Process for recovering polyester from contaminated polyester recovery feedstock

Abstract

Disclosed is a method for recovering polyester from a contaminated polyester recovery feedstock that includes polyester and one or more contaminants. The method of the present disclosure includes the steps of (a) treating contaminated polyester recovery feedstock with a contaminant modifying agent in which said polyester is substantially insoluble to form a treating zone product including at least one modified contaminant and undissolved polyester; (b) separating at least one of the modified contaminant or the undissolved polyester from the treating zone product to form a polyester recovery product that includes undissolved polyester; and optionally (c) recovering the undissolved polyester to form a refined polyester recovery product comprising (i) target polyester and optionally (ii) residual contaminants. The method may further include modifying the target polyester to form various target products.

Description

PROCESS FOR RECOVERING POLYESTER FROM CONTAMINATED POLYESTER RECOVERY FEEDSTOCKFIELD OF THE INVENTION

[0001] The present invention generally relates to the field of polyester recycle and recovery processes and more particularly to polyester recycle or recovery processes that include recovery of polyester from feedstocks that may include polyester with a variety of contaminants.BACKGROUND OF THE INVENTION

[0002] Polyesters are often viewed as the world’s most purchased and diversely utilized class of polymers, with published world production volumes (including recycling) recently reported to be well in excess of 75 million tons. This level of commercial success is likely attributable in part to polyesters’ attractive combination of relative cost, manufacturability and competitive performance attributes. Polyester’s physical, chemical and thermal properties make them useful and desirable for a wide variety of end-use applications. Polyethylene terephthalate (PET) is probably one of the most popular types of polyester for many end-uses. With the continuing commercial success of polyesters generally and PET specifically has come efforts to recover materials from post-consumer, post-industrial, scrap and other sources and re-use those materials as an alternative to basic disposal methods such as landfills.

[0003] In some known recycle methods, recycled PET is blended with virgin materials. This approach has been used, for example, to prepare blends of virgin poly(butylene terephthalate) (“PBT”) with recycled PET to yield a PBT- based product with recycle content (see, for example, U.S. Patent Application Publication No. 2009 / 0275698). Such blends, however, can be generally immiscible and produce a material that is relatively opaque. Blending, therefore, is not a uniformly satisfactory method to provide commercially acceptable end products with recycled content.

[0004] In some known recycle methods, polyesters may be selectively dissolved and recovered as a solution for further processing. For example, in U.S. Patent No. 4,003,880, polyester polymer is recovered from mixed collections of fibers in the form of fibers, filaments, or fabrics (including dyed or undyed fibers other than polyester fibers as well as dyed polyester fibers) and used in the production of new undyed fibers, films and other polymer products through the process of stripping the dye from the polyester fibers by contacting the fabrics with a dye stripping solvent for polyester polymer which is preferably not a solvent for fibers other than polyester fibers at a temperature below which the polyester fibers dissolve and above which the crystalline lattice of the polyester fibers swell so as to release the dye; then removing essentially all of the dye-containing dye-stripping solvent which is not absorbed by the fibers; then contacting the solvent-laden fibers (which may contain residual dye) with sufficient additional solvent under selective dissolution conditions for polyester fibers; then removing the undissolved fibers and any other undissolved impurities from the solution; thereafter precipitating the polyester out of; and, separating the polyester from the solution.

[0005] In other recycle methods, polyesters are depolymerized to form the monomer units originally used in its manufacture. Glycolysis is one commercially utilized method of depolymerizing polyesters. A typical glycolysis process can be illustrated with particular reference to the glycolysis of PET, in which waste PET is dissolved in and reacted with a glycol, typically ethylene glycol, to form a mixture of dihydroxyethyl terephthalate and low molecular weight terephthalate oligomers. This mixture can be subjected to a transesterification reaction, usually in the presence of an ester exchange catalyst, with a lower alcohol such as methanol to form dimethyl terephthalate (DMT) and ethylene glycol(EG), and other monomers, again depending upon the composition of the waste or scrap polyester feedstock. Representative examples of glycolysis methods are disclosed in U.S. Pat. Nos. 3,257,335; 3,907,868; 6,706,843; and 7,462,649, the contents and disclosure of which are hereby incorporated herein by reference.

[0006] Methanolysis is another known and commercially practiced polyester depolymerization method. In methanolysis, the polyester is reacted with methanol as a depolymerization reagent to produce a depolymerized polyester mixture comprising polyester oligomers, dimethyl terephthalate (“DMT”), and ethylene glycol (“EG”). Other monomers such as, for example, 1 ,4- cyclohexanedimethanol (“CHDM”) and diethylene glycol may also be present depending on the composition of the polyester in the methanolysis feed stream and may be target products for certain polyester depolymerization processes. Some representative methods for the methanolysis of PET are described in U.S. Pat. Nos. 3,037,050; 3,321 ,510; 3,776,945; 5,051 ,528; 5,298,530; 5,414,022; 5,432,203; 5,576,456 and 6,262,294, the contents and disclosure of which are incorporated herein by reference. A representative methanolysis process is also illustrated in U.S. Pat. No. 5,298,530, the contents and disclosure of which is incorporated herein by reference. The ‘530 patent describes a process for the recovery of ethylene glycol and dimethyl terephthalate from scrap polyester. The process includes the steps of dissolving scrap polyester in oligomers of ethylene glycol and terephthalic acid or dimethyl terephthalate and passing super-heated methanol through this mixture. The oligomers can comprise any low molecular weight polyester polymer of the same composition as that of the scrap material being employed as the starting component such that the scrap polymer will dissolve in the low molecularweight oligomer. The dimethyl terephthalate and the ethylene glycol are recovered from the methanol vapor stream that flows from the depolymerization reactor.

[0007] One of the biggest challenges in cost-effective polyester recovery related recovery of useful polyester depolymerization target products such as EG and DMT is the presence of non-polyester materials, generally referred to herein as “contaminants”, in the recovery process feedstock. Polyester recovery feedstocks may typically be sourced from plastics recycle collection facilities and similar services or organizations which receive, store and process with limited sorting large quantities of waste plastics for recycle. These collections often include a diverse assortment of many different types andclasses of polymer materials, including polyesters, polyolefins such as polyethylene and polypropylene, polyamides such as Nylon 6, Nylon 6,6, and MDX Nylon, elastanes such as Spandex™ and Lycra™ , polycarbonates, and silicones such as polydimethylsiloxane (PDMS). Further, the waste may include composite materials such as agglomerates, laminates, multilayer films, coated substrates and adhered components that may include multiple plastics materials; additives such as dyes and plasticizers; and catalysts and catalyst residues from the materials original manufacture. The waste may also include impurities such as dirt, glass, paper, minerals, and other non-polymer materials that may also pass through the depolymerization reactor or generate undesirable by-products.

[0008] Whether the contaminant is a non-polyester polymer, a non-polyester additive or a non-polyester impurity, their presence in a waste collection that is a potential source of a polyester recovery feedstock may be problematic. Some contaminants may simply pass through a polyester recovery process unchanged and contaminate the recovery product stream if not removed. Some contaminants may generate (and / or catalyze the formation of) undesirable by-products in the course of polyester depolymerization that, in addition to contaminating the depolymerization product stream, may negatively impact the depolymerization reaction or related target product yield or quality. By way of non-limiting example, Bisphenol-A may be present in a polyester depolymerization product stream when polycarbonate materials are present in the depolymerization feedstock while diesters of adipic acid such dimethyl adipate may be present in a polyester depolymerization product stream when the feedstock includes polyamide materials.

[0009] Separation and subsequent disposal of side-species, by-products and contaminants from the various processing streams within, and / or the final target product stream of, a polyester recovery or depolymerization process can be expensive, capital-intensive, time-consuming and environmentally problematic. The commercial value or utility of at least some of the side species may be changed or improved by conversion to other more useful or valuablecompounds; however, this conversion almost certainly adds additional processing steps (and therefore cost) to the process and must be managed to avoid negative impacts on target product conversion, yield and purity.

[0010] The removal of as many contaminants as possible from the feedstock for a polyester recovery process may reduce the need for contaminant, byproduct etc. removal within or during subsequent processing such as depolymerization or transesterification. Indeed, removal of as many contaminants as possible from the feedstock for a polyester recovery process may facilitate or enable recovery of polyester per se or modified forms thereof. To that end, U.S. Published Patent Application No. 2022 / 0169822A1 describes pre-treating a waste polyester material with dichloromethane (DCM) produce purified polyesterthat can be recycled via any chemical or mechanical recycling process. The described method uses dichloromethane, which is insufficient to properly handle the wide palette of contaminants in recycle collection and which per public information has serious health risks. A continuing and unmet need therefore exists for methods to treat contaminated polyester-containing feedstocks for recovering target products, including polyesters and polyester depolymerization products, utilizing processes that minimize worker hazards, effectively removes contaminants and generate target products of a form and purity for further use.SUMMARY OF THE INVENTION

[0011] In an aspect, the present invention relates to a method for recovering polyester from a contaminated polyester recovery feedstock that includes polyester and one or more contaminants. The method includes the steps of (a) treating the contaminated polyester recovery feedstock with a contaminant modifying agent in which said polyester is substantially insoluble to form a treating zone product including at least one modified contaminant and undissolved polyester; (b) separating at least one of the modified contaminant or the undissolved polyester from the treating zone product to form a decontaminated polyester recovery product that includes undissolvedpolyester; and optionally (c) recovering the undissolved polyester to form a refined polyester recovery product comprising (i) target polyester and optionally (ii) residual contaminants.

[0012] Further aspects of the invention are as disclosed and claimed herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a diagrammatic depiction of at least one exemplary embodiment of the present invention relating to a method for recovering polyester from a contaminated polyester recovery feedstock that includes polyester and one or more contaminants;

[0014] Figure 2 is a diagrammatic depiction of another exemplary embodiment of the present invention relating to a method for recovering polyester from a contaminated polyester recovery feedstock that includes polyester and one or more contaminants;

[0015] Figure 3 is a diagrammatic depiction of yet another exemplary embodiment of the present invention relating to a method for recovering polyester from a contaminated polyester recovery feedstock that includes polyester and one or more contaminants; and

[0016] Figure 4 is a diagrammatic depiction of still another exemplary embodiment of the present invention relating to a method for recovering polyester from a contaminated polyester recovery feedstock that includes polyester and one or more contaminants.DETAILED DESCRIPTION

[0017] The term “polyester” as used herein is meant to generally include without limitation homopolyesters as well as copolyesters, terpolyesters and the like and are typically prepared by reacting a difunctional carboxylic acid or its ester, often a dicarboxylic acid, or mixtures of such acids or esters, with a difunctional hydroxyl compound, often a diol or glycol, or mixtures of such diols or glycols. Alternatively, the difunctional carboxylic acid may be a hydroxy carboxylic acid and the difunctional hydroxyl compound may be an aromaticnucleus bearing 2 hydroxyl substituents such as, for example, hydroquinone. Examples include polyesters having repeating aromatic or cyclic units such as those containing a repeating terephthalate or naphthalate units such as PET and PEN, or those containing repeating furanate repeating units, and although within the definition of PET, it is worth mentioning also those polyesters having repeating terephthalate units and one or more residues or moieties of TMCD (2,2,4,4-tetramethyl-1 ,3-cyclobutanediol), CHDM (cyclohexanedimethanol), propylene glycol, or NPG (neopentylglycol), isosorbide, isophthalic acid, 1 ,4- butanediol, 1 ,3-propane diol, and / or diethylene glycol, or combinations thereof and aliphatic polyesters such as PLA, polyglycolic acid, polycaprolactones, and polyethylene adipates; Polyesters and polyester manufacture are generally well known and are exemplified in for example U.S. Patent Nos. 2,891 ,930 and 2,720,502, assigned to a legacy assignee of the present invention, the contents and disclosure of which are incorporated herein by reference.

[0018] A “polyester recovery process” as the phrase is used herein includes any method, process or system for treatment of polyester-containing feedstocks under conditions to produce or generate target products such as for example polyester, a modified polyester, a co-polyester and / or one or more oligomers or monomers from which polyester may be formed. Non-limiting examples include one or more of (i) separation of insoluble contaminants from a contaminated polyester-containing feedstock; modification of contaminants present in a contaminated polyester-containing feedstock, with optional separation of the modified contaminants; polyester depolymerization methods including without limitation methanolysis depolymerization; alcoholysis depolymerization, e.g., using 2-ethylhexanol as the depolymerizing alcohol; glycolysis depolymerization; pyrolysis depolymerization; hydrolysis depolymerization; and catalyzed reaction of hydrogen with polyester at its ester bonds to reduce them to alcohols (which may be referred to as hydrogenolysis depolymerization); and transesterification of polyester to form modified polyesters or copolyesters.

[0019] The phrase “target product” is used herein to describe one or more of (i) polyester present in a decontaminated polyester recovery feedstock, a treated polyester recovery feedstock or a recovery product from a polyester recovering zone in any form and / or derivatives thereof, expressly including but not limited to modified polyesters or copolyesters formed by transesterification thereof; (ii) useful compound(s) or material(s) from depolymerized polyester (a) on which oligomeric or monomeric unit(s) of a polyester are based and / or (b) are generated in the course of a polyester depolymerization process or the depolymerization of a polyester. Specific non-limiting examples of (ii) above may include dimethyl terephthalate (DMT), dimethyl isophthalate (DMI), or mixtures of DMT and DMI; Bis(2-Hydroxyethyl) terephthalate (BHET); Mono(2- hydroxyethyl) terephthalate (MHET); glycols such as ethylene glycol (EG) as for example when the polyester subject to depolymerization is polyethylene terephthalate (PET); diols such as cis- or trans-cyclohexane-1 ,4-dimethanol (CHDM) or mixtures thereof, cis- ortrans- cyclohexane-1 ,3-dimethanol (CHDM) or mixtures thereof; cis- or trans-cyclobutane-2,2,4,4-tetramethyl-1 ,3- dimethanol (TMCD) or mixtures thereof; diethylene glycol (DEG), neopentylglycol, 1 ,3-propanediol, 1 ,4-butanediol, triethylene glycol; mixtures of DEG and EG; and 1 ,4-phenylenedimethanol or similar 1 ,3- or 1 ,2- phenylenedimethanol isomers.

[0020] The term “zone” is intended to describe a collection of one or more interconnected unit operations and related devices assembled to contribute to achievement of a related system or method purpose or purposes. In nonlimiting examples relevant to the present invention, a “depolymerization zone” may include a reacting or depolymerizing operation employing suitable apparatus or systems such as a reactor or depolymerizer; a “separating zone” may include one or more unit operations to separate various components of a multicomponent material refine a material such as separating, extracting, distilling, evaporating, condensing, decanting, crystallizing, filtering and the like employing suitable apparatus such as a extractor, distillation column, evaporator, condenser, decanter, crystallizer, filter and the like. A “recoveryzone” may include one or more unit operations to recover and / or recycle one or more components such as separating, extracting, distilling, evaporating, condensing, decanting, crystallizing, precipitating filtering and the like employing suitable apparatus such as a extractor, distillation column, evaporator, condenser, decanter, crystallizer, filter and the like. One or more zones may overlap though diagrammatically depicted as separate in the Figures.

[0021] The present invention is described herein with respect to various interrelated aspects and embodiments, including but not limited to a method for decontaminating a contaminated polyester recovery feedstock that includes polyester and at least one contaminant and a method for recovering or depolymerizing polyester. One of ordinary skill will understand and appreciate that elements or features used to describe one aspect or embodiment may be applicable and useful in describing other embodiments. Accordingly, descriptions and disclosure relating to elements or features of an aspect or embodiment of the present invention are hereby expressly relied on to describe and support those elements or features in other aspects or embodiments.

[0022] The present invention, in a first aspect and with reference to Figures 1 through 4, is directed to a method for recovering polyester from a contaminated polyester recovery feedstock 1 that includes polyester and one or more contaminants. In one or more exemplary embodiments, the polyester may be in solid or solid particulate form. In one or more exemplary embodiments, the method may optionally include a step of procuring a contaminated polyester recovery feedstock including polyester and one or more contaminants. The procuring step may include one or more suitable procurement methods, systems or processes, including by way of non-limiting example collecting or assembling or having collected or assembled contaminated polyester recovery feedstock; receiving, purchasing or otherwise obtaining a contaminated polyester recovery feedstock from another party such as plastics recycler and the like.

[0023] The method of the present invention may include the steps of a) treating the contaminated polyester recovery feedstock in a treating zone with a contaminant modifying agent in which said polyester is substantially insoluble to form a treating zone product including at least one modified contaminant and undissolved polyester; (b) separating at least one of the modified contaminant or the undissolved polyesterfrom the treating zone product in a separating zone to form a decontaminated polyester recovery feedstock recovery product that includes undissolved polyester; and optionally (c) recovering the undissolved polyester in a polyester recovering zone to form a refined polyester recovery product comprising (i) target polyester and optionally (ii) residual contaminants. As depicted in Figures 1 through 4, the treating step (a) may be performed in a treating zone 10 and separating step (b) may be performed in a separating zone 30. The contaminated polyester recovery feedstock 1 and contaminant modifying agent 2, as well as optional additives such as for example water or aqueous salt solution 3, may be fed into treating zone 10. Though depicted as separate streams in the Figures, one will appreciate that the depicted streams may be combined prior to treating step or may be introduced into treating zone 10 sequentially or simultaneously or in any order or combination. T reating zone 10 may be any suitable vessel or vessels such as one or more of a mixing tank, reactor, columnar vessel, or the like or combinations thereof. Product from treating zone 10, which may be referred to as treating zone product and which is shown for example at 4 in the Figures, incudes undissolved polyester may include one or more of modified contaminant, for example in the form of solubilized contaminant, contaminant reaction product solids or swelled contaminant solids; unmodified or insoluble contaminant; and carrier liquid that may include contaminant modifying agent and optionally water or aqueous salt solution or other liquids or carriers fed to the treating zone 10.

[0024] The contaminated polyester recovery feedstock may include polyester and one or more contaminants. A “contaminant” as the term is used herein includes any polymeric, oligomeric, inorganic or organic materials present in a contaminated polyester recovery feedstock other than polyesters.Specific non-limiting examples of contaminants may include non-polyester polymers, including polyolefins such as polyethylene and polypropylene and copolymers thereof; polyamides such as Nylon 6, Nylon 6,6, and MDX Nylon; elastanes such as Spandex™ and Lycra™, polycarbonate, and silicones such as polydimethylsiloxane (PDMS). Contaminants may also include composite materials such as agglomerates, laminates, multilayer films, fibers, woven fabrics, meshes, coated substrates and adhered components that may include one or more polymer, oligomer or organic materials that may be non-polyesters; additives such as dyes and plasticizers; adhesives; catalysts and catalyst residues, e.g., from a material’s original manufacture; packaging materials such as paper, cardboard, wood, including said materials coated with clay, plastics, waxes, and the like; general waste or detritus, such as stones, pebbles, rocks, food residue, metal implements or artifacts such as screws, wire, pop tops, and the like.

[0025] The method of the present invention may include treating the contaminated polyester recovery feedstock with a contaminant modifying agent. The phrase “contaminant modifying agent” is intended to include agents that modify the molecular morphology or physical form of a contaminant. In at least one exemplary embodiment, the contaminant modifying agent may be a liquid. In at least one exemplary embodiment, the contaminant modifying agent may be non-reactive with the contaminant, meaning that the modification of the contaminant by the contaminant modifying agent does not result in a change in contaminant molecular structure or identity and is unreactive with the contaminant. In at least one exemplary embodiment, the contaminant modifying agent may be reactive with the contaminant, meaning that the modification of the contaminant by the contaminant modifying agent results in a change in contaminant molecular structure or identity and is reactive with the contaminant. In such embodiments, the contaminant modifying agent may include a contaminant reacting agent that reacts with a contaminant to form a contaminant reaction product in the treating step. In one or more example embodiment, the treatment step forms a modified contaminant and undissolvedpolyester, preferably in a carrier liquid. Polyester may be substantially insoluble in the contaminant modifying agent under the conditions of the treating step and may therefore be described as undissolved or unsolubilized or insoluble. Though the polyester may be undissolved, in some embodiments the polyester may be swelled such that the method or the treating step may include swelling polyester to form swelled polyester.

[0026] In at least one exemplary embodiment, the contaminant modifying agent is a solvent for a contaminant and the treating step includes dissolving or solubilizing the contaminant to form a contaminant solution including dissolved or solubilized contaminant. The term “solvent” is intended to include agents that are capable of at least partially dissolving or solubilizing the contaminant under a given set of treating step conditions (e.g., temperature, pressure, time, contaminant / contaminant modifying agent amounts and contaminant modifying agent concentration). One will appreciate that a solvent for a contaminant may at least partially dissolve or solubilize the contaminant under a specified set of treating step conditions and may alternatively swell or otherwise modify the contaminant under a separate specified set of treating step conditions. Accordingly, in at least one exemplary embodiment, the contaminant modifying agent is a solvent for said contaminant and the treating step includes swelling a contaminant to form swelled contaminant solids. The term “swelling” is intended to describe the permeation of contaminant modifying agent into the structure (for example polymer matrix) of a contaminant resulting in a decrease in density. In at least one exemplary embodiment, the contaminant modifying agent is a swelling agent for the contaminant and the treating step includes swelling the contaminant to form a swelled contaminant solids. One will appreciate that, as described above, solvents may act as swelling agents for a contaminant under a given set of treating step conditions; however, materials other than solvents may act to swell contaminants and, therefore, the swelling agent may be a non-solvent for the contaminant. In at least one exemplary embodiment, the swelled contaminant is substantially free from tack or the capacity to adhere to solid surfaces such as undissolved material, processingequipment and the like. In at least one embodiment, the swelled contaminant is substantially free from gel.

[0027] In at least one exemplary embodiment, at least one of said one or more contaminants may be substantially insoluble under treating step conditions, forming treating zone product that includes at least one insoluble contaminant. “Insoluble” as used herein is intended to describe materials which remain primarily in a generally unmodified, solid form during and immediately exiting the treating step as a component of the treating zone product. Nonlimiting examples of typically insoluble contaminants include cotton / cellulose, regenerated cellulose (rayon); carbon black; metals, exemplified by aluminum, steel, copper artifacts, such as wires, pop tops, screws, nails, textile detritus, including zippers, snaps, buttons, rivets, and the like; inorganics exemplified by TiO2, silicon dioxide, clays, rocks, gravel, pebbles and the like; polyolefins exemplified by polypropylene and polyethylenes such as LDPE and HDPE; PVC, including polyunsaturated backbones depleted in chlorine (as compared to virgin PVC) which may be generated via PVC decomposition during the treating step.

[0028] In one or more exemplary embodiments, the contaminant modifying agent includes a contaminant reacting agent and the modified contaminant includes contaminant reaction product solids. Examples of contaminant reacting agents may include anhydrides of C2 to C8 carboxylic acids such as acetic anhydride, propionic anhydride, butyric anhydride, benzoic acid anhydride, 2-ethylhexanoic acid anhydride, mixed anhydrides of C2 to C8 carboxylic acids, C2 to C8 carboxylic acid chlorides such as acetyl chloride, and the like. In one or more exemplary embodiments, in particular but not exclusively embodiments wherein the contaminant includes cellulose or a derivative thereof such as viscose or regenerated cellulose, the treating step may include swelling with a contaminant swelling agent (for example acetic acid, which may swell cellulose and activate it for reaction) and then treating swelled contaminant with an anhydride (such as acetic anhydride) contaminant reacting agent in the presence of acid (e.g., sulfuric acid) catalyst to convert thecellulose to a cellulose ester (such as cellulose acetate). In another embodiment, the cellulose contaminant may be reacted with a mixture of acetic anhydride and propionic anhydride, or a mixture of n-butyric anhydride and acetic anhydride to form a cellulose mixed ester. In another embodiment, rayon may be swelled with acetic acid and the swelled contaminant reacted with acetic, propionic, or butyric anhydrides, or mixtures thereof.

[0029] In one or more exemplary embodiments, the treating step may form more than one form of modified contaminant, for example a solubilized contaminant and a swelled contaminant.

[0030] In one or more exemplary embodiments, the treating step (a) may be performed in the presence of water or an aqueous salt solution. In one or more exemplary embodiments, the treating step may be performed in the presence of water or aqueous salt solution in an amount of from 10 wt% to 90 wt% water or aqueous salt solution based on the total weight of the contaminated polyester feedstock, aqueous salt or water, and contaminant modifying agent mixture, or in a mass ratio of water or aqueous salt solution to contaminated polyester feedstock of 1 / 1 to 10 / 1. In one or more exemplary embodiments, the aqueous salt solution comprises water and a water-soluble ionic compound formed from cations of Group I A, IB, 11 B, and VIII elements, such as K, Na, Cs, Li, Mg, Ca, Sr, Be, Cu, Zn, Ni, Fe and an anion selected from Group VI I A elements, such as Cl or Br, or anions such as sulfate, phosphate or hydrogen phosphate, dihydrogen phosphate, C1 to C4 carboxylate, such as acetate, propionate, i / n- butyrate, carbonate or hydrogen carbonate, citrate, glutarate. Lactate, Triflate, trifluoroacetate. Said water-soluble ionic compounds should have sufficient solubility in water such that a resulting salt-water solution has a density between 1 .05 and 1.35 g / cc, more preferably 1.15 to 1 .30 g / cc, at temperatures between about 15°C and 90°C, more preferably 17°C to 75°C. Examples of suitable salts are BaCl2, potassium acetate, potassium propionate, potassium butyrate, sodium acetate, cesium acetate, cesium propionate, cesium butyrate, CsCI, CsNOs, CS3PO4, K2CO3, KHCO3, CuSO4, CaCI2, CaNO3, calcium acetate, CuCI2, Fe2(SO4)3, FeSO4, K2HPO4, K3PO4, KBr, KCI, KH2PO4, KNO3, LiSO4,LiCI, LiNOs, Mg(NO3)2, MgCh, MgSO4, Na2CO3, Na2HPO4, Na3PO4, NaH2PO4, Na2SO4, NaBr, NaN03, Ni(NO3)2, NiCI2, NiSO4, ZnCI2, ZnSO4, ZnBr, SrCI2, Sr(NO3)2, CsCI, CSNO3, Tripotassium citrate, trisodium citrate, potassium tritiate, potassium trifluoracetate, calcium lactate, potassium lactate cesium lactate, potassium glutarate, cesium glutarate. In one or more exemplary embodiments, the aqueous salt solution may have a density of about 1.2 g / cc at a relatively lower temperatures, for example from 17°C to 75°C, as exemplified in Table A below. In one or more exemplary embodiments, the salt solution may include from 15% by weight to 35 % by weight salt.TABLE ATABLE A

[0031] The presence of water or an aqueous salt solution may be particularly advantageous in embodiments wherein the modified contaminant may be a swelled contaminant and a separating step following the treating step may include floatation or other density separation. When the contaminant is a swelled contaminant, a preferred mass ratio of water or aqueous salt solution to contaminated polyester feedstock is 2 / 1 to 10 / 1 , more preferably 3 / 1 to 7 / 1.

[0032] In one more exemplary embodiment, the treating step (a) forms a treating zone product shown at 4 as product in the Figures, that includes at least one modified contaminant and undissolved polyester, preferably in a carrier liquid. In one or more exemplary embodiments, the carrier liquid includes contaminant modifying agent. In one or more exemplary embodiments,the carrier liquid may include a solvent for the contaminant. In one more exemplary embodiment, the carrier liquid may include a swelling agent for the contaminant. In one or more exemplary embodiments, the carrier liquid may include a contaminant reacting agent. In one more exemplary embodiment, the carrier liquid may include one or more of water or an aqueous salt solution.

[0033] The composition of the treating zone product may vary depending on a variety of factors, including for example contaminated feedstock composition, modifying agent(s) identity and concentration and treating step conditions. In one or more embodiments, for example wherein the treating step includes solubilizing a contaminant, the treating zone product may include solubilized contaminant. In one or more embodiments, for example wherein the treating step includes swelling a contaminant, the treating zone product may include swelled contaminant solids. In one or more embodiments, for example wherein the treating step includes reacting a contaminant, the treating zone product may include contaminant reaction product solids. Further, the treating step may include more than one contaminant modification. For example, the treating step may include solubilizing a first contaminant and swelling a second contaminant, thereby generating a treating zone product the includes solubilized contaminant and swelled contaminant solids. Other combinations of contaminant modifications and modified contaminants will be apparent to one of ordinary skill.

[0034] As depicted in the Figures, the treating step may include in some embodiments include at least partial separation functionality enabling separation of undissolved polyester from one or more of modified contaminant and insoluble contaminant, such that treating step (a) also forms a treated contaminant effluent, shown at 5, that includes one or both of insoluble contaminant and modified contaminant. Treating step contaminant effluent 5 may be formed for example in embodiments where the treating step includes sequential substeps as described elsewhere herein. To the extent the contaminant in treated contaminant effluent 5 may be useful for recovery or reuse, the contaminant may be recovered in treated contaminant recovery zone20 to form recovered treating step contaminant 8 as shown in Figures 2 through 4. Suitable recovery methods may include one or more of dewatering techniques such as centrifugation, pressing, augering; drying; evaporation; incineration; adding water as a contaminant recovery enhancement agent, combined with distilling via azeotropic distillation. Said recovery methods may be accomplished batchwise or continuously, with one or more of the methods occurring sequentially. In one or more embodiments, treated contaminant effluent 5 may include contaminant modifying agent which is separated from effluent 5 in treated contaminant recovery zone 20 and optionally recycled to treating zone as shown at 21 in Figures 2 through 4.

[0035] To reduce the amount of contaminated feedstock that must be treated, in at least one exemplary embodiment, polyester and / or contaminants may be removed from the contaminated polyester recovery feedstock, for example by density flotation separation, prior to or concurrent with treating step a). Accordingly, in one or more exemplary embodiments, the method of the present invention may include, prior to treating step (a), a step of removing or segregating at least one of contaminants and polyester from the contaminated polyester recovery feedstock. In one or more exemplary embodiments, this removing or segregating step may include the separating one or more contaminants and / or polyester from the polyester-containing contaminated polyester recovery feedstock by density separation. Examples of density separation are known in the art and include flotation separation, static media density separation, gravity separation, magnetic density separation and hydrocyclone separation such as separation with cylindroconical and cylindrical cyclone-type media separators. In one non-limiting example, the density of the polyester polyethylene terephthalate (PET) in relatively pure form may be from about 1.3 to 1.4 g / cc and this PET will sink in aqueous salt solutions with densities less than 1 .3 g / cc. In contrast, composite polyethylene-PET materials may have densities less than 1 .2 g / cc and will float or remain suspended in said solutions, with the “sink / float” mechanism facilitating separation of relatively pure PET and the composite from the contaminated feedstock.

[0036] In at least one exemplary embodiment, the at least one contaminant may be selected from the group consisting of polyolefins, polyurethanes, elastanes, PVC, polyamides, silicones, adhesives such as ethylene-vinyl alcohols and polyurethanes, polycarbonates, cotton, cellulose, regenerated cellulose, dyes and combinations thereof. In one or more exemplary embodiments, the contaminant modifying agent may be selected from a group consisting of C3 to C11 ketones, including in particular acetone and a mix of C11 ketones commercially available from Eastman Chemical; more preferably C5-C9 ketones such as methyl propyl ketone (MPK), methyl amyl ketone (MAK), methyl isoamyl ketone (MIAK), di-isobutyl ketone (DIBK), methyl isobutyl ketone (MIBK), di-isopropyl ketone (DIPK), methyl isopropyl ketone (MIPK) and combinations such as mixes of C7 or C9 ketones sold by Eastman Chemical; C6 to C13 aromatics such as naphthalenes, toluene, xylenes and mixed xylenes, preferably C7 to C10 aromatics; aromatic fluids known in the art as Aromatic 150, Aromatic 200, Solvesso™ 150 and Solvesso™ 200 and sold commercially by Exxon Mobil™ and combinations; C6 to C14 alkanes, preferably C7 to C11 alkanes such as undecane, isoparaffin fluids such as Isopar™ L; C4 to C10, preferably C5 to C8, alkyl esters, such as ethyl, propyl, butyl, acetates, propionates, and butyrates; C8 to C12, preferably C8 to C1 , aromatic esters; C3 to C8 aliphatic secondary and tertiary amides; C5-C8 secondary and tertiary lactams and similar cyclic amides, exemplified by N- methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone, N- butyl-2-pyrrolidone, dimethylacetamide, diethylacetamide, dimethyl propanamide, dimethyl butanamide, dimethylformamide, diethylformamide and 1 ,3-Dimethyl-2-imidazolidinone, C1 to C8 alkanols and glycols, as exemplified by methanol, ethanol, propanol isomers, butanol isomers, cyclohexanol, ethylene glycol, diethylene glycol, triethylene glycol, CHDM, propanediol and butanediol isomers; C3 to C8 glycol ethers and glycol ether carboxylate esters, exemplified by EG, DEG, and 1 ,2-PDO mono ethers of ethanol, propanol, and butanol and corresponding esters, EG, 1 ,2-PDO, and DEG diethers of ethanol, propanol, and butanol; C7 to C10, preferably C7 to C8, aromatic alcohols; C2to C4 carboxylic acids with soluble salts of Group HA cations with anions selected from chloride, bromide, acetate, propionate, lactate, trifluoracetate, triflate, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate, sulfate, chloroacetate wherein said salt is soluble in said contaminant modifying agent at least at a 0.25M concentration, preferably C2 to C3 carboxylic acids with Ca and Mg salts of chloride, acetate, propionate, lactate, trifluoroacetate, triflate and nitrate; C1 to 02 alkanols with soluble salts of Group HA cations with anions selected from chloride, bromide, acetate, propionate, lactate, trifluoracetate, triflate, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate, sulfate, chloroacetate wherein said salt is soluble in said contaminant modifying agent at least at a 0.25M concentration, preferably C1 to 02 alkanols with Ca and Mg salts of chloride, acetate, propionate, lactate, trifluoroacetate, triflate and nitrate and combinations thereof. In at least one exemplary embodiment, the calcium salt may be an organic calcium salt such as for example calcium acetate or calcium lactate, or a halo-organic calcium salt such as calcium trifluoroacetate or calcium triflate. In one or more embodiments, the contaminant modifying agent may be a mixture of aromatic or amide and C2 to C8 glycols, preferably ethylene glycol, diethylene glycol, CHDM, triethylene glycol, wherein the mixture includes 5-50 wt% glycol with the remainder aromatic or amide.

[0037] In general, the treating step may be performed under conditions (for example time, temperature, pressure and contaminant modifying agent type and concentration) to achieve maximum conversion of contaminants to modified contaminants while maintaining polyester in an undissolved form. In one or more exemplary embodiments, the contaminant modifying agent may be a liquid and the treating step may be performed under conditions sufficient to maintain the contaminant modifying agent and any water or salt solution in the liquid phase such that the treating step product includes a carrier liquid. One of ordinary skill may appreciate that conditions for the treating step may vary and may be selected based on several factors including without limitation type, number and physical form (including particle size) of contaminant(s) in thecontaminated polyester recovery feedstock, choice of contaminant modifying agent and choice of contaminant modification mechanism(s) (e.g., swelling, reaction, or a combination thereof). In one or more exemplary embodiments, the treating step may be performed under conditions of high shear, mixing or similar agitation.

[0038] In one or more exemplary embodiments, the treating step may be performed at a temperature of from -15°C to 190°C. In one or more exemplary embodiments, the treating step may be performed at a pressure of from about 1 bara to 15 bara. In one or more exemplary embodiments, the time or period for the treating step may be from 30 seconds to 6 hours. In one or more exemplary embodiments, the treating step may be performed at a modification mass ratio (MMR), defined as the mass ratio of contaminant modifying agent to contaminant present in the contaminated polyester recovery feedstock that is modified by the contaminant modifying agent, of 0.1 / 1 to 10 / 1. As used herein, exemplary MMR levels relate primarily to and are described for the purpose of achieving the desired contaminant modification such as for example swelling. Excess modification agent may nonetheless be included, for example, to create additional effects such as fluidity or flowability of the system while remaining within the spirit and scope of the invention.

[0039] It may be understood by those skilled in the art that treating step time may be highly dependent on particle size, particle size distribution, morphology and physical form of the contaminated feedstock and / or contaminant components. Such understanding may be particularly but not exclusively applicable to embodiments wherein a dissolved contaminant is formed. Accordingly, in one or more exemplary embodiments, the contaminated polyester recovery feedstock includes at least one of contaminant and polyester with a particle size no more than 5000 microns in any dimension or no more than 2000 microns in any dimension or no more than 1000 microns in any direction or no more than 500 microns in any dimension. Accordingly, in one or more exemplary embodiments, the contaminated polyester recovery feedstock preferably includes at least one of the contaminant and polyester inthe form of flakes, shreds, fibers, powders or grindings. While less preferable, the contaminated polyester recovery feedstock may include at least one of contaminant and polyester in the form or densified (material that has been heated, at least partially melted and melded together) or extruded materials.

[0040] Waste polyester from extruder operations is typically collected as large semi-crystalline slabs of material which is ground into chunks or fines. Said ground material often has a large particle size and highly variable particle size distribution. A materially significant fraction (0.5 to 5 wt%) may comprise large pieces (1 to 5 cm in largest dimension) which are particularly difficult to process in ways to recover the polyester, for example to depolymerize, in a similar residence time as smaller feedstock pieces. Accordingly, in one or more exemplary embodiments, the method may include a step of reducing the feedstock particle size prior to the treating step. In some embodiments, the step of reducing feedstock particle size may include physical particle size reduction such as grinding, crushing or the like. In some embodiments, the step of reducing feedstock particle size may contacting the feedstock with a contaminant modifying agent mixture comprising of C6 to C13 aromatics with C2 to C8 glycols, wherein the mixture includes 5-50 wt% glycol, at elevated temperatures, typically 160-190°C for 1 to 6 hours residence time. Exemplary aromatics are naphthalenes, toluene, xylenes and mixed xylenes; aromatic fluids known in the art as Aromatic 150, Aromatic 200, Solvesso™ 150 and Solvesso™ 200 and sold commercially by Exxon Mobil™ and combinations. Exemplary C2 to C8 glycols are preferably ethylene glycol, diethylene glycol, CHDM, triethylene glycol. The polyester component of the feedstock chunks tends to become friable, and readily reduce upon shearing (i.e., during mixing, pumping) to particle sizes of no more than 5000 microns in any dimension or no more than 2000 microns in any dimension or no more than 1000 microns in any direction or no more than 500 microns in any dimension with somewhat reduced molecular weight as compared to before such treatment.

[0041] In one or exemplary embodiments, particularly including but not limited to treating steps using either a solvent or swelling agent and in whichthe treating step forms swelled contaminant solids, the treating step may be performed at a temperature of from 15°C to 100°C, more preferably from 20°C to 80°C In one or exemplary embodiments, particularly including but not limited to treating steps using either a solvent or swelling agent and in which the treating step forms a swelled contaminant, the treating step may be performed at a pressure of from 1 bara to 15 bara or from about 1 bara to 8 bara. In one or exemplary embodiments, particularly including but not limited to treating steps using either a solvent or swelling agent and in which the treating step forms swelled contaminant solids, the period or time for the treating step may be from about 30 seconds to 25 minutes or from 5 minutes to 20 minutes total treating time. In one or more exemplary embodiments, particularly including but not limited to treating steps using either a solvent or swelling agent and in which the treating step forms a swelled contaminant, the treating step may be performed at a modification mass ratio (MMR) of from about 0.1 / 1 to about 3 / 1 of from 0.2 / 1 to 1.5 / 1. As used herein, exemplary MMR levels relate primarily to and are described for the purpose of achieving the desired contaminant modification such as for example swelling. Excess modification agent may nonetheless be included to for example provide carrier liquid functionality or create additional effects such as fluidity or flowability of the system while remaining within the spirit and scope of the invention. In one or exemplary embodiments, particularly including but not limited to treating steps using either a solvent or swelling agent and in which the treating step forms swelled contaminant solids, the treating step may be performed in the presence of a surfactant. Suitable surfactants may include anionic surfactants such as sulfonated derivatives of C8 to C18 alkanols, exemplified by sodium lauryl sulfate, and sodium tetradecyl sulfate, or nonionic surfactants, exemplified by polyoxyethylene sorbitol esters, commonly known as Tween ®.

[0042] In one or exemplary embodiments, particularly including but not limited to treating steps using a solvent and in which the treating step forms a dissolved or solubilized contaminant, the treating step may be performed at a temperature of from 15°C to 190°C, more preferably from 60°C to 175°C In oneor exemplary embodiments, particularly including but not limited to treating steps using a solvent and in which the treating step forms a dissolved or solubilized contaminant, the treating step may be performed at a pressure of from 1 bara to 15 bara or from about 1 bara to 8 bara. In one or exemplary embodiments, particularly including but not limited to treating steps using a solvent and in which the treating step forms a dissolved contaminant, the period or time for the treating step may be from 10 minutes to 6 hours or from 20 minutes to 4 hours. In one or exemplary embodiments, particularly including but not limited to treating steps using a solvent and in which the treating step forms a dissolved contaminant, the treating step may be performed at a modification mass ratio (MMR) of from about 1 / 1 to 10 / 1 or from 2 / 1 to 6 / 1. As used herein, exemplary MMR levels relate primarily to and are described for the purpose of achieving the desired contaminant modification such as for example swelling. Excess modification agent may nonetheless be included to for example create additional effects such as fluidity or flowability of the system while remaining within the spirit and scope of the invention.

[0043] In another exemplary embodiment where the contaminant is dissolved in the contaminant modifying agent, water or aqueous salt solution may be added to the solubilized contaminant solution to reduce the concentration of the solid undissolved polyester feedstock components, to improve mixing and flow. Further, for contaminant modifying agents that are immiscible with the water or salt solution, the separation in the separation zone, described in more detail elsewhere herein, may be improved by the solubilized contaminant solution forming a second lighter liquid phase that floats on top of the water or salt solution phase, and to which a polyester component sinks into said water or salt solution layer. The approach of exploiting liquid-liquid separation is particularly favorable for contaminants and contaminant modifying agents that are immiscible with water, such as polyolefins dissolved in alkanes, ketones, or aromatics; PVC dissolved in ketones or esters; polycarbonate dissolved in ketones or aromatic esters.

[0044] In one or more exemplary embodiments, particularly including but not limited to treating steps using contaminant reacting agent and forming contaminant reaction product solids, the treating step may be performed at a temperature of from -15 °C to 75°C or from 0°C to 50°C. In one or exemplary embodiments, particularly including but not limited to treating steps using a contaminant reacting agent and in which the treating step forms a contaminant reaction product, the treating step may be performed at a pressure of from 1 bara to 5 bara or from about 1 bara to 2 bara. In one or exemplary embodiments, particularly including but not limited to treating steps using a contaminant reacting agent and in which the treating step forms a contaminant reaction product, the period or time for the treating step may be from 20 minutes to 6 hours or from 45 minutes to 4 hours. In one or more exemplary embodiments, particularly including but not limited to treating steps using a contaminant reacting agent and in which the treating step forms a contaminant reaction product, the treating step may be performed at a mass ratio of from about 0.5 to 8 or from 1 to 4 of combined (optional) contaminant modifying agent and contaminant reacting agent to contaminant.

[0045] One of ordinary skill may appreciate that, in some cases, the contaminated polyester recovery feedstock may include an unknown or unmeasured amount of contaminant. Accordingly, in one or more exemplary embodiments the treating step may be performed at a feedstock-based mass ratio (FMR), defined as the mass ratio of contaminant modifying agent to contaminated polyester recovery feedstock, of from 0.5 / 1 to 5 / 1 or from 1 / 1 to 3 / 1. Though these FMR ranges are preferable, lower FMRs ratios that may produce a very thick and difficult-to-mix material may be successfully processed in the presence of water or aqueous salt solution.

[0046] One will appreciate that identification and selection of treating step variables such as treatment time, choice and amount of contaminant modifying agent and treating step conditions may vary depending on a number of factors, including without limitation presence or absence of a specific contaminant, amount of contaminant, presence or absence of various contaminantcombinations in the feedstock, desired modification, e.g., swelling of contaminant by the contaminant modifying agent, reaction of contaminant with contaminant modifying agent, and the like.

[0047] In at least one exemplary embodiment, at least one of the one or more contaminants in the feedstock may include PVC and the contaminant modifying agent may be selected from the group consisting of C3 to C11 , preferably acetone or C5 to C9, ketones; C4 to C10, preferably C5 to C8, alkyl esters; C8 to C12, preferably C8 to C10, aromatic esters; C6 to C14, preferably C7 to C10, aromatics, C7 to C10, preferably C7 to C9, aromatic alkanols. In one or more embodiments wherein the one or more contaminants includes PVC, the treating step may include swelling PVC or solubilizing PVC. In general, it has also been observed that PVC may decompose or partially decompose to produce HCI (which may be soluble in treating step contaminant modifying agent or solvent) and a polyunusaturated PVC backbone. Accordingly, in one or more embodiments wherein the one or more contaminants includes PVC, the treating step may include decomposing PVC, including but not limited to solubilized PVC, to form HCI and a Cl-depleted polyunusaturated PVC backbone. The treating step may further include neutralizing the formed HCI with a neutralizing species to form a neutralized chlorine salt. Neutralizing species may include alkali and alkali earth salts of C1-C8 carboxylic and dicarboxylic acids, exemplified by acetic, propionic, butyric acid sodium, potassium, lithium, calcium, magnesium salts; alkali and alkali earth carbonate and bicarbonate salts, exemplified by sodium, potassium, lithium, calcium, magnesium carbonates and bicarbonates. The neutralizing species may be soluble in the contaminant modifying agent or insoluble in the contaminant modifying agent. Alkali and alkali earth hydroxides and alkoxides may also function as neutralizing species, but are less favored, as such strong bases may lead to excessive reaction or hydrolysis of polyester bonds, resulting in the formation of terephthalyl salts. The neutralized chlorine salt may be present in the treating zone product and accordingly may be separated from the treating zone product. In one or more embodiments wherein the one ormore contaminants includes PVC, the treating step may include solubilizing or swelling the formed polyunsaturated PVC backbone. Suitable contaminant modifying agents for swelling or solubilizing the polyunsaturated PVC backbone may include C6 to C13 aromatics preferably C7 to C10 aromatics and C6 to C14 alkanes, preferably C7 to C11 alkanes such as undecane, isoparaffin fluids such as Isopar™ L. Exemplary aromatics are naphthalenes, toluene, xylenes and mixed xylenes; aromatic fluids known in the art as Aromatic 150, Aromatic 200, Solvesso™ 150 and Solvesso™ 200 and sold commercially by Exxon Mobil™ and combinations thereof. Suitable treating step temperatures for solubilizing the polyunsaturated PVC backbone may range from 150 to 190. In one or more embodiments wherein the at least one contaminant non-polyester comprises PVC, the treating step may include melting the formed polyunsaturated PVC backbone. In one or more embodiments wherein the at least one contaminant non-polyester comprises PVC, the treating step may include solubilizing and decomposing PVC. In one or more embodiments wherein the at least one contaminant non-polyester comprises PVC, the treating step may include solubilizing PVC; decomposing the solubilized PVC and to form HCI and a Cl-depleted polyunusaturated PVC backbone and swelling or dissolving the Cl-depleted polyunusaturated PVC backbone.

[0048] In at least one exemplary embodiment, the at least one contaminant may include dyes and the contaminant modifying agent may be selected from the group consisting of C5 to C11 ketones, preferably C5-C9 ketones; C4 to C10 alkyl esters, preferably C5 to C8 esters; C3 to C8 aliphatic secondary and tertiary amides; C5-C8 secondary and tertiary lactams and similar cyclic amides, exemplified by N-methyl-2-pyrrolidone (NMP); C6 to C12 aromatics, preferably C7 to C10 aromatics; C7 to C10, preferably, C7 to C8, aromatic alcohols; C2 to C6 carboxylic acids, preferably C2 to C4 carboxylic acids; C2 to C4 carboxylic acids with soluble salts of Group HA cations with anions selected from chloride, bromide, acetate, propionate, lactate, trifluoracetate, triflate, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate, sulfate, chloroacetate wherein said salt is soluble in said contaminant modifyingagent at least at a 0.25M concentration, preferably C2 to C3 carboxylic acids with Ca and Mg salts of chloride, acetate, propionate, lactate, trifluoroacetate, triflate, nitrate; C1 to 010 alkanols, preferably 04 to 08 alkanols; 01 to 03 alkanols with soluble salts of Group HA cations with anions selected from chloride, bromide, acetate, propionate, lactate, trifluoracetate, triflate, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate, sulfate, chloroacetate wherein said salt is soluble in said contaminant modifying agent at least at a 0.25M concentration, preferably 01 to 02 alkanols with Ca and Mg salts of chloride, acetate, propionate, lactate, trifluoroacetate, triflate, nitrate; and combinations thereof.

[0049] In one or more embodiments, the at least one contaminant may include dyes and the contaminant modifying agent of the treating step may include one or more of: aliphatic C1-C8 secondary and tertiary amides; C1-C10 secondary and tertiary lactams and similar cyclic amides. Exemplary suitable amides include N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone, N-propyl- 2-pyrrolidone, N-butyl-2-pyrrolidone, dimethylacetamide, diethylacetamide, dimethyl propanamide, dimethyl butanamide, dimethylformamide, diethylformamide and 1 ,3-Dimethyl-2-imidazolidinone. In one or more embodiments, the contaminant modifying agent may be a mixture of amide and C2 to 08 glycols, preferably ethylene glycol, diethylene glycol, CHDM, triethylene glycol, wherein the mixture includes 5-50 wt% glycol with the remainder amide. A glycol / amide mixture may be particularly efficacious for contaminated polyester recovery feedstocks comprising crystalline or semicrystalline polyester of large particle size (i.e., greater than 5 mm average diameter chunks), with the glycol believed to assist in large particle dissolution by swelling the polyester matrix and promotes transformation into a friable solid. Accordingly, in some embodiments, the treating step may further include swelling the polyester with a swelling agent such as glycol.

[0050] In embodiments in particular wherein the contaminated polyester recovery feedstock includes dyed material, for example at least one of dyed polyester and dyed contaminant non-polyester, treating step conditions may beselected to facilitate leaching of the dye from the dyed material as well as solubilization of the dye. Accordingly, in one or more embodiments, the treating step may include leaching contaminant dye from dyed material or from one or more of dyed polyester and dyed contaminant non-polyester. As used herein, the term “leaching” is intended to generally describe removal of solute into a solvent from solid material. Depending on preferred nomenclature and definitional nuance, one of ordinary skill may similarly refer to the removal of solute into a solvent from solid material as extracting.

[0051] In at least one exemplary embodiment, the at least one contaminant may include polyolefins and the contaminant modifying agent may be selected from the group consisting of C5 to C1 1 ketones, preferably C5-C9 ketones; C6 to C12 aromatics, preferably 07 to 010 aromatics; 06 to 014 alkanes, preferably C7 to C11 alkanes; C4 to C10, preferably 05 to C8, alkyl esters; C8 to C12, preferably C8 to 010, aromatic esters; and combinations thereof. It has been observed that polyolefins may be insoluble under some treating step conditions but may melt under some treating step conditions. Accordingly, in one or more embodiments, the at least one contaminant non-polyester may include polyolefin and the treating step may include melting the polyolefin to form a polyolefin melt in said treating zone product. In one or more embodiments, the treating zone product may include a polyolefin melt phase and a contaminant modifying agent phase and the method may further include separating the polyolefin melt phase from the contaminant modifying agent phase. The separating step may include cooling the treating zone product to solidify or precipitate the polyolefin melt. In one or more embodiments, the one or more contaminants may include polyolefin and the treating step may include swelling the polyolefin. In one or more embodiments, the one or more contaminants may include polyolefin and the treating step may include swelling and melting the polyolefin.

[0052] In at least one exemplary embodiment, the at least one contaminant may include polyamides and the contaminant modifying agent may be selected from the group consisting of C1 to C10, preferably C7 to C8, aromatic alcohols;C5 to 011 , preferably C5 to C8; C8 to C12, preferably C8 to C10, aromatic esters; C2 to C4 carboxylic acids with soluble salts of Group IIA cations with anions selected from chloride, bromide, acetate, propionate, lactate, trifluoracetate, triflate, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate, sulfate, chloroacetate wherein said salt is soluble in said contaminant modifying agent at least at a 0.25M concentration, preferably C2 to C3 carboxylic acids with Ca and Mg salts of chloride, acetate, propionate, lactate, trifluoroacetate, triflate and nitrate; C1 to C2 alkanols with soluble salts of Group IIA cations with anions selected from chloride, bromide, acetate, propionate, lactate, trifluoracetate, triflate, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate, sulfate, chloroacetate wherein said salt is soluble in said contaminant modifying agent at least at a 0.25M concentration, preferably C1 to C2 alkanols with Ca and Mg salts of chloride, acetate, propionate, lactate, trifluoroacetate, triflate and nitrate; alkanes, and combinations thereof.

[0053] In at least one exemplary embodiment, the at least one contaminant may include elastanes and the contaminant modifying agent may be selected from the group consisting of C1 to C10, preferably C7 to C8, aromatic alcohols; C5 to C11 , preferably C5 to C8, ketones; C8 to C12, preferably C8 to C10, aromatic esters; C2 to C4 carboxylic acids with soluble salts of Group IIA cations with anions selected from chloride, bromide, acetate, propionate, lactate, trifluoracetate, triflate, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate, sulfate, chloroacetate wherein said salt is soluble in said contaminant modifying agent at least at a 0.25M concentration, preferably C2 to C3 carboxylic acids with Ca and Mg salts of chloride, acetate, propionate, lactate, trifluoroacetate, triflate and nitrate; C1 to C2 alkanols with soluble salts of Group IIA cations with anions selected from chloride, bromide, acetate, propionate, lactate, trifluoracetate, triflate, nitrate, phosphate, hydrogen phosphate, dihydrogen phosphate, sulfate, chloroacetate wherein said salt is soluble in said contaminant modifying agent at least at a 0.25M concentration, preferably C1 to C2 alkanols with Ca and Mg salts of chloride, acetate,propionate, lactate, trifluoroacetate, triflate and nitrate; alkanes, and combinations thereof.

[0054] In at least one exemplary embodiment, the at least one contaminant may include polycarbonates and the contaminant modifying agent may be selected from the group consisting of C5 to C11 , preferably C5 to C9, ketones; C4 to C10, preferably 05 to 08, alkyl esters; 08 to 012, preferably C8 to C10, aromatic esters, and combinations thereof.

[0055] In at least one exemplary embodiment, the at least one contaminant may include silicones and the contaminant modifying agent may be selected from the group consisting of C8 to C12, preferably 08 to C10, aromatic esters and combinations thereof.

[0056] In at least one exemplary embodiment, the at least one contaminant may include one or more of cotton, cellulose and regenerated cellulose and the treating step may include swelling the contaminant with a contaminant modifying agent selected from the group consisting of C2 to 06 carboxylic acids and combinations thereof and treating the swelled contaminant with a contaminant reacting agent including one or more anhydrides of C2 to C8 carboxylic acids in the presence of acid catalyst, Suitable C2 to C6 carboxylic acids include acetic acid, propionic acid, and butyric acid. Suitable anhydrides of 02 to 08 carboxylic acids include acetic anhydride, propionic anhydride, butyric anhydride, benzoic acid anhydride, 2-ethylhexanoic acid anhydride, mixed anhydrides of 02 to 08 carboxylic acids, C2 to C8 carboxylic acid chlorides such as acetyl chloride, and the like. Suitable catalyst includes sulfuric acid.

[0057] In one or more exemplary embodiments, more than one of the one or more contaminants may be modified concurrently or as a single step in the treating step (a). In such embodiments, the treating step is performed at conditions at which at least one contaminant is modified in the treating step. As described above, the treating step product from the treating step may include insoluble contaminants which may be separated from the treating zone product in a separating step or in some embodiments during or prior to the treating step.

[0058] In one or more embodiments, more than one of the one or more contaminants may be modified sequentially or in multiple substeps or in sequential substeps in the treating step (a). In such embodiments, the treating step (a) may include substep (a1 ) treating the contaminated polyester recovery feedstock with a contaminant modifying agent under conditions in which a first of said one or more contaminants is modified, forming a treating zone product intermediate comprising a first modified contaminant and undissolved polyester and substep (a2) treating said treating zone product intermediate with a contaminant modifying agent under conditions in which a second contaminant is modified, forming treating zone product comprising the second modified contaminant. In embodiments where the substep (a1 ) forms a first modified contaminant that is separable from the treating zone product intermediate, for example when the first modified contaminant includes a swelled contaminant, the treating step may include a substep (a1.5) of separating the first modified contaminant from the treating zone product intermediate between substeps (a1 ) and (a2). Insofar as the treating zone product intermediate may further include insoluble contaminants, the method may in some embodiments further include removing insoluble contaminants from the treating zone product intermediate or the treating zone product. In one or more exemplary embodiments, the contaminant modifying agent of substep (a1 ) and the contaminant modifying agent substep (a2) may be the same contaminant modifying agent (from the standpoint of molecular structure). In one or more exemplary embodiments, substep (a2) may be performed at a temperature higher than the temperature of substep (a1 ). In one or more exemplary embodiments, the temperature of substep (a1 ) may be no more than 130°C and the temperature of substep (a2) may be at least 160°C. In embodiments wherein the contaminated polyester recovery feedstock includes dyed materials such as one or more of dyed polyester and dyed contaminant, the dye contaminant may be leached from the dyed material and solubilized in substep (a1 ). Accordingly, substep (a1) may in some embodiments include leaching contaminant dye from such dyed materials. In one or more exemplary embodiments, the contaminant modifyingagent of substep (a1 ) and the contaminant modifying agent of substep (a3) may be different agents (from the standpoint of molecular structure). In one or more exemplary embodiments, the contaminant modifying agent may include or consist of or consist essentially of N-Methyl-2-pyrrolidone or N,N-dimethyl acetamide. In one or more exemplary embodiments, the method may further include a step of adding an additional amount of contaminant modifying agent after substep (a2) and prior to or concurrent with substep (a2). In one or more exemplary embodiments, the one or more contaminants may include one or more of cellulosics, polyolefin, elastane, dye, polycarbonate, adhesive and polyamide. In one or more exemplary embodiments, the contaminated polyester recovery feedstock may include a polyester blend textile product that may include polyester fibers and one or more of cotton, olefin, spandex and polyamide fibers. In one or more exemplary embodiments, the method may further include a step of removing solubilized contaminant dye from the treating zone product.

[0059] As a general matter, treating step product 4 includes undissolved polyester and may, depending on treating step conditions or type and number of treating step substeps, include one or more modified contaminants. In one or more exemplary embodiments, treating step product includes undissolved polyester and one or more solubilized contaminants. In one or more exemplary embodiments, treating step product includes undissolved polyester and one or more swelled contaminants. In one or more exemplary embodiments, treating step product includes undissolved polyester and one or more contaminant reaction products. In one or more exemplary embodiments, treating step product includes undissolved polyester, one or more solubilized contaminants and one or more swelled contaminants. In one or more exemplary embodiments, treating step product includes undissolved polyester, one or more solubilized contaminants and one or more contaminant reaction products. In one or more exemplary embodiments, treating step product includes undissolved polyester, one or more swelled contaminants and one or more contaminant reaction products. In one or more exemplary embodiments,treating step product includes undissolved polyester, one or more swelled contaminants, one or more contaminant reaction products and one or more solubilized contaminants.

[0060] In some embodiments, the treating step (a) may include substep (a1 ) treating said contaminated polyester recovery feedstock with at least one contaminant modifying agent under conditions in which a first contaminant is solubilized, forming a treating zone product intermediate comprising insoluble contaminant and solubilized contaminant and substep (a2) removing at least some of said one or more insoluble contaminants from said treating zone product intermediate.

[0061] The method of the present invention may include a step of separating insoluble contaminant from said treating zone product (or in applicable embodiments a treating zone product intermediate) either as part of the treating step or in a separating step to form a polyester recovery product that includes undissolved polyester and optionally one or more modified contaminant. In brief, the separating step and the separating zone involve separating the treating zone product into one or more components and providing a polyester recovery product which includes polyester suitable for recovery, re-use and / or further modification. As discussed elsewhere, insoluble contaminants may include without limitation typically solid materials such as cotton, cellulose and regenerated cellulose (rayon), collectively cellulosics; carbon black; metals, exemplified by aluminum, steel, copper artifacts, such as wires, pop tops, screws, nails, textile detritus, including zippers, snaps, buttons, rivets, and the like; inorganics exemplified by TiO2, silicon dioxide, clays, rocks, gravel, pebbles and the like. Such insoluble contaminants may be separated in the separating step by known solid / liquid separation techniques such as filtering, sedimentation, centrifugation and the like. In one or more embodiments, such as embodiments that include polyolefins exemplified by polypropylene and polyethylenes such as LDPE and HDPE as a contaminant, the treating zone product may include polyolefin melt or may include a polyolefin melt phase and a contaminant modifying agent phase, and the separating step may includeseparating the polyolefin melt phase from said contaminant modifying agent phase. In embodiments wherein PVC is a contaminant and the treating step may include decomposing PVC to form HCI and a decomposed polyunsaturated PVC backbone and neutralizing the HCI with a neutralizing species to form a neutralized chloride salt in said treating zone product, the separating step may include separating one or both of the neutralized chloride salt and the decomposed polyunsaturated PVC backbone from the treating zone product In one or more embodiments, the method of the present invention may include solubilizing the polyunsaturated PVC backbone, for example as a component of the separating step or the treating step. In one or more embodiments, the method of the present invention may include filtering out the neutralized chloride salt and polyunsaturated PVC backbone (if insoluble in the contaminant solvent), for example as a component of the separating step or the treating step. In another embodiment wherein one or both of the polyunsaturated PVC backbone or neutralized chloride salt is solubilized, said contaminants may be removed from the polyester in a polyester washing step.

[0062] Tables B-1 through B-9 below present data generated on feedstocks that included various contaminants and contaminant modifying agents and employing various treating step conditions. The data represents testing primarily for embodiments wherein the contaminant modifying agent dissolved, swelled or reacted with a contaminant under the indicated treating step temperatures or temperature ranges while the polyester remained undissolved. Accordingly, contaminant dissolution, swelling or reaction without polyester dissolution may be presumed to have occurred in the Tables B-1 to B-9 data (and is occasionally but not exclusively indicated with an “S” or “R” respectively) except as expressly indicated otherwise. Further, as contaminant modification without polyester solubilization was a primary criteria for the testing, testing time period and modifying agent concentration was varied in some experimental runs to determine whether contaminant solubilization could be achieved. For some experimental runs, preliminary experiments were performed using onlycontaminants in various physical forms such as fibers or fabrics (i.e., without the presence of polyester) to generally define suitably effective contaminant modifying agents and treating step conditions for select contaminants prior to treating a polyester-containing feedstock including those contaminants. T reating step pressures were selected to maintain the carrier liquid / contaminant modifying agent in the liquid phase in addition to the above-described criteria.TABLE B-1 - DYESF = Float, D= solubilizes Cl-depleted backbone from PVC, Cl-depletion accelerated at higher T's above 150C# must contain naphthalene ringR = reacts, begins to depolymerize PET even without catalystTABLE B-2 - SILICONESTABLE B-3 - PVCTABLE B-3 - PVC* S= solubilizes F = Float, D= solubilizes Cl-depleted backbone, Cl-depletion accelerated at higher T's above 150C# must contain naphthalene ringR = reacts, begins to depolymerize PET even without catalystTABLE B-4 - POLYCARBONATETABLE B-5 - POLYOLEFIN* S= solubilizes F = Float, D= solubilizes Cl-depleted backbone, Cl-depletion accelerated at higher T's above 150C# must contain naphthalene ringR = reacts, begins to depolymerize PET even without catalystTABLE B-6 - ADHESIVESTABLE B-7 - ELASTANESTABLE B-7 - ELASTANESTABLE B-8 - CELLULOSICSTABLE B-9 - POLYAMIDETABLE B-9 - POLYAMIDE

[0063] An exception to solubilization was observed and is listed under the “polyolefins” category of Table B-5, and is identified with a letter “F” to indicate that the contaminant polyolefin melted and formed a floating melt phase component in a two-phase treating step product that included a separate contaminant modifying agent phase. Another exception to solubilization was observed and is listed under the “PVC” category of Table B-3 and is identified with a letter “D” to indicate that the contaminant PVC decomposed as evidenced by formation of a black residue and the detectable generation of HCI.

[0064] Table C below presents data wherein certain contaminant modifying agents were demonstrated as particularly preferred for solubilization of specific contaminants. Table C also includes a general indication of contaminant modifying agents found to potentially interact with the polyester in the feedstock depending on selected treating step conditions. Notably, swelling of the polyester without solubilization thereof may be desirable in some embodiments and, accordingly, the method may include swelling undissolved polyester to form swelled polyester.TABLE CTABLE C

[0065] Table D below presents data generated by performing the method of the present invention on feedstocks that included PVC or cellulosic contaminants and selected contaminant modifying agents and employing varying treating step conditions, with the data representing testing primarily for embodiments wherein the contaminant modifying agent swelled (PVC) or reacted (cellulose) with the contaminant under the indicated treating step temperatures or temperature ranges.TABLE DRestrict

[0066] In at least one exemplary embodiment, the method may further include a step of reducing the average particle size of the feedstock prior to the treating step. Suitable particle size reducing methods, and related systems and equipment, are known in the art and are exemplified without limitation by grinding, tearing, crushing, comminuting, shredding, pulverizing, cryogrinding, chopping, shearing, sonically grinding, and the like. Moreover, the step of reducing the average particle size of the feedstock reduction step may include contacting the feedstock with particle size reduction facilitator such as a contaminant modifying agent or swelling agent in embodiments wherein such treatment may facilitate particle size reduction.

[0067] While treating step in general includes treating contaminant with contaminant modifying agent to form modified contaminant, the specific conditions of the treating step may be varied so as to create different or multiple modifications to a contaminant. Accordingly, a modified contaminant may include multiple modifications to first and second modifications in some embodiments. Further, a modified contaminant may include a first modification under a first set of treating step conditions and a second modification, or a first and second or multiple modifications, under a second set of treating step conditions. Depending on for example treating step temperature, a contaminant such as polyolefin may be melted but not solubilized and thereby form melted contaminant. In such embodiments, the modified contaminant may form a phase separate from the carrier liquid present in the treating zone product. In another non-limiting example, contaminants (for example PVC) may be both solubilized and decomposed in a treating step to form solubilized, decomposed contaminant. Depending on for example treating step temperature and time, a contaminant such as PVC may be decomposed but not solubilized to form decomposed contaminant.

[0068] In at least one exemplary embodiment, the polyester recovery feedstock includes a composite material comprising a polyester component and a contaminant component coupled together. In general, the phrase “composite material” may include any unitary material wherein a polyester and acontaminant are both present. Non-limiting examples of composite materials may include agglomerates; laminates; multilayer constructions such as films, flooring and the like; coated substrates; materials that may include multiple polymer components coupled for example by heat bonding or adhesive; multicomponent or blended fiber fabrics and textiles, and similar constructions. In one non-limiting example, a polyester recovery feedstock may have agglomerated and formed agglomerates over time, for example by exposure to increased temperature, compression, or other storage conditions such as humidity. Further, a polyester recovery feedstock may have been purposefully processed to improve handling or transport, with such processing (e.g., increased temperature, compression, or extrusion, or combinations therein) causing formation of agglomerates. One of ordinary skill may appreciate that, for purposes of achieving the numerous benefits of the present invention, including effectiveness, productivity, processing speed and target product yields, presence or formation of agglomerates in the feedstock prior to the treating step should be avoided or limited. To the extent purposeful processing generates agglomerates, the benefits of such processing should be weighed against any negative impact on the method of the present invention. In general, the presence of agglomerates may be reduced or eliminated by particle size reduction techniques described herein.

[0069] In at least one exemplary embodiment, the method of the present invention may include mechanically separating the polyester component and the contaminant component of a composite material. In at least one exemplary embodiment, the treating step of the method of the present invention may include mechanically separating the polyester component and the contaminant component of a composite material. In at least one exemplary embodiment, method of the present invention may include applying a friction force to mechanically separate any polyester component and contaminant component of a composite material that remains coupled together after the treating step. In at least one exemplary embodiment, method of the present invention may include applying a friction force to mechanically separate undissolved polyesterand swelled contaminant of a composite material that remains coupled together after the treating step. Non-limiting examples of applying a friction force may include high shear mixing, abrading, scraping, grinding and the like. In at least one exemplary embodiment, the step of applying a friction force is preceded by a step of swelling one or more of the contaminant components and the polyester of a composite material. Swelling affects the dimensional stability of the contaminant / PET interface, facilitating frictional separation, which may create subparticles of swelled contaminant and particles enriched in PET content from particles of the original composite material. Swelling of polyester may be achieved for example by hydrogenated terphenyls, alkyl napthalenes, or phenyl ethers.

[0070] In one or more exemplary embodiments, the contaminant modifying agent may include a solvent that dissolves an adhesive that facilitates separation of the PET and a contaminant. In one non-limiting example, adding a contaminant modifying agent may include a solvent that dissolves an ethylene vinyl alcohol adhesive coupling polyolefin to PET layers of a composite material.

[0071] In at least one exemplary embodiment, the step of applying a friction includes creating swelled contaminant agglomerates or subparticles, as such agglomerates or subparticles which facilitate further processing of the modified contaminant, for example to recover contaminant modifying agent.

[0072] One will appreciate that, for contaminants that include composite materials, the treating step perse may in some embodiments facilitate or effect partial or total separation of the polyester component and the contaminant component of a composite material contaminant. Accordingly, in at least one exemplary embodiment, the method of the present invention may include a treating step that includes separating the polyester component and the contaminant component of a composite material.

[0073] The method of the present invention may include separating one or both of the modified contaminant and / or the undissolved polyester from the treating zone product to form a decontaminated polyester recovery feedstock.The decontaminated polyester recovery feedstock may include undissolved polyester. In some embodiments, the separating step may include separating the undissolved polyester from carrier liquid. In at least one exemplary embodiment wherein the contaminant modifying agent dissolves the contaminant, the method of the present invention may include a separating step that may include filtering undissolved polyester from a contaminant solution including contaminant modifying agent and dissolved contaminant. In one or more embodiments, the separating step may include filtering undissolved polyester from the treating zone product.

[0074] In one or more exemplary embodiments, the separating step may be performed in the presence of water or an aqueous salt solution. Suitable aqueous salt solutions are described elsewhere herein with respect to the treating step that precedes the separating step and / or are listed in Table 1 herein. In one or more exemplary embodiments, the treating step may be performed in the presence of water or aqueous salt solution in an amount of from 10 wt% to 90 wt% water or aqueous salt solution based on the total weight of the treating zone product, aqueous salt solution or water, and contaminant modifying agent mixture, or in a mass ratio of water or aqueous salt solution to treating zone product of 1 / 1 to 10 / 1.

[0075] In one or more exemplary embodiments, in particular but not exclusively in embodiments wherein the treating step forms a solubilized contaminant, the separating step may include separating undissolved polyester from the treating zone product and washing the undissolved polyester with a wash solution. The wash solution may at least partially remove residual materials such as one or more of residual contaminant, modified contaminant or aqueous salt solution from the undissolved polyester. The wash solution may include contaminant modifying agent, other materials suitable for washing such as solvents in which the contaminant(s) are soluble, or a combination of these. The wash solution typically is fed at a solid / wash solution ratio of 0.25 / 1 to 6 / 1 , more typically 0.75 / 1 to 3 / 1. The washing may include displacement washing wherein the wash solution displaces interstitial liquid in a plug flow manner ormay involve dilution washing wherein the wash solution combines with the undissolved polyester to form a slurry or other flowable form which may be transferrable to another vessel for further processing.

[0076] As depicted in Figures 1 through 4, the separating step may be performed in a separating zone 30 which receives treating zone product 4 from treating zone 10 and in which one or more components of treating zone product 4 are separated from each other. The separating zone 30 for separating step may include one or more processes, devices or systems for solid / liquid separation, such as for example belt filters, rotary filters, candle filters, bag filters, plate and frame filters, screen / scroll, pusher centrifuges, peeler centrifuges, inverting filter centrifuges, sliding discharge centrifuges, pendulum centrifuges, sedimentation centrifuges, hydrocyclones, sedimentation vessels. Said solid / liquid separation devices may be operated under vacuum or pressurized conditions, in batch or continuous mode, as a single unit, or in one or more units in series or parallel format. The specific methods, systems and devices for the separating step may vary, depending for example on the type, amount and number of modified contaminants, type and amount of contaminant modifying agent(s) and the like. For embodiments wherein the contaminant is dissolved in the contaminant modifying agent, the separating zone 30 may be operated at temperature and pressure conditions similar to the treating zone, i.e. , 15°C to 190°C, preferably 20°C to 170°C, more preferably 20°C to 150°C at a pressure sufficient to keep all components in the liquid phase and the contaminant fully dissolved, about 1 bara to 15 bara, more preferably about 1 bara to 8 bara.

[0077] In at least one exemplary embodiment and as depicted in Figures 1 through 4, the separating step forms (i) a decontaminated polyester recovery product 32 that includes undissolved polyester and (ii) modified contaminant stream 31 . In embodiments wherein the separating step includes filtering, the stream 31 may be labeled contaminant filtrate 31. In at least one exemplary embodiment, the decontaminated polyester recovery product 32 further includes carrier liquid or contaminant modifying agent. As described in moredetail elsewhere herein relating to embodiments with PVC contaminant, neutralizing species for PVC HCI decomposition product may be added at stream 33. Stream 33 may alternatively be a stream for adding contaminant recovery enhancement agent or anti-solvent as described elsewhere herein.

[0078] In at least one exemplary embodiment, the method of the present invention may include a separating step that may include classifying swelled contaminant solids and undissolved polyester by density differential separation. One will appreciate that, in embodiments that may include a swelling agent and / or generation of swelled contaminant, a numeric difference in the density between swelled contaminant, undissolved polyester and carrier liquid from treating zone product 4 may be established and / or increased, and such density differential may be utilizable in classifying and / or separating the swelled contaminant and / or undissolved polyester from the carrier. By way of nonlimiting example, known “sink / float” or “flotation” density separation, wherein a component less dense than a carrier floats to or near its surface while a second component that may be more dense than a carrier does not float to the surface of the carrier or may sink to or near its bottom. “Flotation” density separation, as well as other density differential separation techniques, are described for example in U.S. Patent No. 4,617,111 , the contents and disclosure of which are hereby incorporated herein by reference.

[0079] One of ordinary skill will be appreciate that, in some embodiments, the treating zone product may include contaminants that may not be modified by the contaminant modifying agent and may therefore be described as unmodified contaminants. Though preferably removed at least in part during the treating step at zone 20, at least some amount of such unmodified contaminants, may remain in treating zone product 4. Accordingly, in one or more embodiments, the separating step may further include separating unmodified contaminant from the treating zone product. To the extent such unmodified contaminants may have a numeric difference in density between them and the undissolved polyester, this separating step may include classifying unmodified contaminant by density differential separation. In at leastone exemplary embodiment, the method of the present invention may include a separating step that includes separating at least one of modified contaminant and undissolved polyester from the treating zone product.

[0080] Modified contaminant stream 31 may include, for example, dissolved contaminant in a contaminant solution and / or swelled contaminant in liquid carrier and may more generally include a combination of one or more modified contaminant and contaminant modifying agent. Accordingly, in at least one exemplary embodiment, the method of the present invention may optionally include recovering at least one of the contaminant and the contaminant modifying agent from the modified contaminant stream of the separating step. This recovering step may be carried out either batch-wise or continuously. With reference to Figures 2b and 3, the recovering step may be performed in a contaminant recovering zone 50. Contaminant recovering zone 50 may include one or more processes, systems and devices to extract or otherwise separate contaminant modifying agent from modified contaminant. Recovering step in recovering zone 50 forms contaminant modifying agent recovery stream 51 that includes contaminant modifying agent and contaminant recovery stream 55. At least one exemplary embodiment, contaminant modifying agent recovery stream 51 may be recycled to the treating step in treating zone 10. Recovering step may be performed in the presence of a recovery enhancement agent (see stream 52). Accordingly, in at least one exemplary embodiment, the method of the present invention may include recovering one or more of the contaminant modifying agent and the contaminant. Further, in one or more exemplary embodiments, the method of the present invention may include recycling contaminant modifying agent to the treating step.

[0081] In one or more exemplary embodiments, the contaminant recovering step may include separating modified contaminant from the modified contaminant stream. In one or more exemplary embodiments, the recovering step may include separating swelled contaminant from the modified contaminant stream. In one or more embodiments, the contaminant recovering step may include precipitating or crystallizing solubilized contaminant from themodified contaminant stream. In at least one exemplary embodiment, the recovering step may include precipitating or crystallizing solubilized contaminant from a solubilized contaminant solution including contaminant solubilized in contaminant modifying agent. In one or more exemplary embodiments, precipitated or crystallized contaminant may be recovered from the modified contaminant stream via solid-liquid separation methods known in the art, such as filtration, centrifugation, hydroclonization, sedimentation, and the like. More generally, methods for the recovering step may involve one of several methods known in the art to assist in, or result in, precipitation or crystallization of the contaminant; controlled indirect cooling via heat exchange of the contaminant solution to reduce the solubility of the contaminant in the contaminant solution; controlled direct cooling, i.e., evaporative cooling, of the contaminant solution by boiling and removal from the contaminant solution of the contaminant modifying agent or another component added as an evaporative cooling agent; concentration of contaminant via distillation, evaporation or other vapor-liquid equilibrium-based separation method, of at least a part of the contaminant modifying agent to increase the level of supersaturation of the contaminant; addition into the contaminant solution a recovery enhancement agent such as an anti-solvent component for the contaminant; evaporative drying of the contaminant solution, such as by spray drying; or combinations thereof. In one or more exemplary embodiments, the contaminant recovering step is performed in the presence of a contaminant recovery enhancement agent, shown in the Figures as added to the contaminant recovering zone as stream 52, and which in general may include any materials that may enhance or increase the yield or purity of recovered contaminant and / or recovered contaminant modifying agent from the recovering step. In one or more exemplary embodiments, the recovery enhancement agent has low or essentially no solubility for the contaminant at the recovering step conditions. In one or more exemplary embodiments, the contaminant recovery enhancement agent may be miscible with the contaminant modifying agent and / or may modify the solubility characteristics ofthe contaminant modifying agent by reducing the solubility of the contaminant. The effectiveness of the contaminant recovery modifying agent may be enhanced at higher concentrations relative to the contaminant modifying agent. In at least one exemplary embodiment, the contaminant recovery enhancement agent has a boiling point higher than the contaminant modifying agent or forms a minimum boiling azeotrope with the contaminant modifying agent. In one nonlimiting example, the contaminant recovery enhancement agent may include or consist essentially of or consist of water or an anti-solvent for a solubilized contaminant.

[0082] In one or more exemplary embodiments, this recovering step may include cooling the modified contaminant stream to an end solidifying temperature. In general, an end solidifying temperature is a temperature at which a modified contaminant that is in liquid or flowable form such as for example a solution or melt, transitions to a solid, for example by solidification of a melt, precipitation or crystallization. A cooling profile for direct or indirect heat removal may span a temperature range from the dissolution temperature used in the treating zone to an end solidifying temperature at which wherein a precipitating polymer contaminant is not sticky and forms free particles. In one or more exemplary embodiments the end solidifying temperature may be less than 100° or less than 80°C.

[0083] For polyolefins the end solidifying temperature is typically less than 100°C, more preferably less than 80°C or even less than 60°C. When the contaminant modifying agent is an alkane, a preferred recovery method is direct or indirect cooling of the contaminant solution to induce precipitation of the polyolefins. When the contaminant modifying agent is an aromatic, ketone, or ester, a preferred recovery method is addition of water as a contaminant recovery enhancement agent and distillative removal of the contaminant modifying agent via azeotrope formation with water.

[0084] For PVC the end solidifying temperature is typically less than 60°C, more preferably less than 40°C or even less than 30°C and is highly dependent on the amount of contaminant modifying agent present. Preferred recoverymethods include spray drying, concentration, with and without direct heat exchange, and adding water as a contaminant recovery enhancement agent, combined with distilling via azeotropic distillation.

[0085] For polyamides and elastanes the end solidifying temperature is typically less than 80°C, more typically less than 60°C or even less than 40°C. For polyamides and elastanes dissolved in alcoholic or carboxylic acid salt contaminant modifying agent, e.g., acetic acid and a calcium salt, a preferred method of recovery of the contaminant may be a combination of contaminant recovery enhancement agent addition and cooling. The preferred contaminant recovery enhancement agent is water, with a water addition rate of 0.5 / 1 water / contam inant modifying agent weight ratio to 0.05 / 1 weight ratio, more preferably 0.2 / 1 to 0.1 / 1 weight ratio, at an end solidifying temperature of 50°C to 20°C. For polycarbonate, the end solidifying temperature is typically less than 60°C, more preferably less than 40°C or even less than 30°C and is highly dependent on the amount of contaminant modifying agent present. Preferred recovery methods include spray drying, concentration, with and without direct heat exchange, and water as a contaminant recovery enhancement agent or contaminant recovery enhancement agent, combined with azeotropic distillation.

[0086] For cellulose or regenerated cellulose that has been converted to a cellulose ester via contaminant reacting agent in the treating step, the end solidifying temperature is typically less than 60°C, more preferably less than 40°C or even less than 30°C and is highly dependent on the amount of contaminant modifying agent and contaminant reactant present. A preferred recovering step includes adding contaminant recovery enhancement agent, wherein the contaminant recovery enhancement agent is water or a C1 to C3 alkanol.

[0087] Dyes (including dyes modified by contaminant modifying agent) may preferably be recovered via concentration, spray drying, or contaminant recovery enhancement agent addition with azeotropic distillation of the contaminant modifying agent. The recovering step for dyes is typically carriedout at temperatures lower than 150°C, with the corresponding pressure level to allow boiling of the contaminant modifying agent and contaminant recovery enhancement agent if present.

[0088] In at least one exemplary embodiment, the contaminant recovering step may include separating swelled contaminant into contaminant modifying agent and de-swelled contaminant. The phrase “de-swelled contaminant” is intended to describe swelled contaminant from which contaminant modifying agent or solvent or swelling agent has been substantially removed from the polymer matrix thereof. In at least one exemplary embodiment, the recovering step may include contacting swelled contaminant with water, preferably at a temperature of from 60°C to 120°C, to form a water / contaminant modifying agent azeotrope. This contacting step may be performed at a pressure of, for example, 0.2 bara to 2.0 bara.

[0089] In one or more exemplary embodiments, this recovering step may include boiling off one or more of a contaminant modifying agent and a water / contaminant modifying agent azeotrope. In one or more exemplary embodiments, the recovering step may include drying swelled contaminant. This drying step may be performed at a temperature of from 50°C to 150°C. and a pressure of from 1 bara to 2 bara. This drying step may optionally be performed in the presence of an inert stripping gas such as nitrogen.

[0090] The separating step may form a decontaminated polyester recovery product, shown at 32, that includes undissolved polyester. In some embodiments, the undissolved polyester of the polyester recovery product may be suitable “as-is” for recovery, re-use and / or further modification, for example in embodiments with contaminated feedstocks having a limited number of contaminants or contaminants which all solubilize in the treating step. Accordingly, the undissolved polyester may be referred to as “target” polyester. Nonetheless, in one or more exemplary embodiments or aspects, the undissolved polyester of decontaminated polyester recovery product 32 or refined polyester recovery product 72 may serve as a component of a feed for a modifying step wherein the undissolved “target” polyester is modified, forexample depolymerized according to one or more polyester depolymerization processes known in the art, transesterified as described elsewhere herein, or otherwise modified such as dissolved or melted. Accordingly, in embodiments that include a modifying step, stream 32 may be described and labeled in the Figures herein as a feedstock 32. Feedstock 32 may nonetheless include limited amounts of carrier liquid that do not materially impact any further recovery or modification steps.

[0091] In one or more exemplary embodiments, the decontaminated polyester recovery product 32 may further include non-polyester materials such as carrier liquid, modified contaminant (in particular solubilized contaminant) contaminant, water and / or aqueous salt solution. Accordingly, in one or more exemplary embodiments, the method may further include recovering undissolved polyester from the polyester recovery product 32. As depicted in Figures 3 and 4, the polyester recovering step may be performed in a polyester recovering zone 70 which may include one or more processes, systems and devices to separate or further separate undissolved polyester from one or more of liquid carrier, solubilized contaminant, contaminant, contaminant modifying agent, water and / or aqueous salt solution that may be present in the polyester recovery product 32. Suitable devices, processes and systems for separating undissolved polyester from one or more of liquid carrier, modified contaminant, contaminant, water and / or aqueous salt solution may include solid-liquid separation methods known in the art, such as filtration, centrifugation, hydroclonization, sedimentation, and the like, and combinations thereof. Recovering step may in one or more embodiments form contaminant modifying agent recovery stream 71 that includes one or more contaminant modifying agents; modified contaminant recovery stream 75 which may include modified contaminant, and a refined polyester recovery product 72. In one or more embodiments, the step of recovering undissolved polyester may include treating the polyester with a polyester recovery enhancement agent, shown in the Figures as added to polyester recovery zone 70 via recovery enhancement agent stream 73. The polyester recovery enhancement agent may include anymaterials that may enhance or increase the yield or purity of polyester from the recovering step. At least one exemplary embodiment, contaminant modifying agent recovery stream 71 may be recycled to the treating step in treating zone 10. Accordingly, in at least one exemplary embodiment, the method of the present invention may include recovering one or more of contaminant and contaminant modifying agent. Further, in one or more exemplary embodiments, the method of the present invention may include recycling contaminant modifying agent to the treating step. To the extent modified contaminant and / or contaminant modifying agent from the recovering step in recovering zone 70 may be commercially useful, the method may further include recovering one or more of modified contaminant and contaminant modifying agent from modified contaminant recovery stream 75 of recovering step 70. As depicted in Figures 3 and 4, the step of recovering one or more of modified contaminant and contaminant modifying agent from modified contaminant recovery stream 75 may be performed in a contaminant recovering zone 80. In one or more exemplary embodiments, the contaminant recovering step separates modified contaminant from contaminant modifying agent via solid-liquid separation methods known in the art, such as filtration, centrifugation, hydrocyclonization, sedimentation, and the like. Contaminant modifying agent from this recovering step may recycled to treating step and shown in Figure 4 at 84. Recovered modified contaminant from this recovering step, as shown in Figures 3 and 4 at 85, may be further processed to recover contaminant. The recovering step may be performed in the presence of a recovery enhancement agent (see stream 83), which in general may include any materials that may enhance or increase the yield or purity of recovered contaminant, modified contaminant and / or contaminant modifying agent from the recovering step.

[0092] In one or more exemplary embodiments, the recovering step of the present invention may be preceded by, or include, washing undissolved polyester with a wash solution that includes for example one or more contaminated modifying agents.

[0093] In one or more exemplary embodiments, the method of the present invention may include recovering one or more of the contaminant modifying agent and the contaminant. In one or more exemplary embodiments, the method of present invention may include recycling a recycle stream comprising contaminant modifying agent to the treating step. As depicted in the Figures, the recycling step may include one or more of recycling contaminant modifying agent recovery stream 71 , contaminant modifying agent recovery stream 51 and modified contaminant stream 31.

[0094] While zones such as the treating zone, separating zone and recovering zone depicted diagrammatically as spatially separate in the Figures for convenience, one of ordinary skill will appreciate that treating and separating functions with the methods and systems of the present invention may overlap. For example, treating zone may include some amounts or all of a separating function. Similarly, some amount of a contaminant treating function to form modified contaminant may occur in separating zone. Indeed, in one or more embodiments, separating zone may, as a spatial arrangement matter, overlap with or be partially or wholly contained within a treating zone. In some embodiments, therefore, the method may be described as batch, insofar as treating and separating steps are performed sequentially in a singular zone or sequentially in a singular vessel. In some embodiments, the method may be described as semi-continuous or continuous insofar as treating and separating steps may be performed at least partially in separate zones or vessels.

[0095] As described elsewhere herein, decontaminated polyester recovery product 32 and refined polyester recovery product 72 may be referred to as feedstocks in certain embodiments that may include a modifying step. Accordingly, in some embodiments, the method of the present invention may further include in some embodiments a step (d) of modifying target polyester. Non-limiting examples of modifying, described in more detail below, may include one or more of washing with a wash solution); dissolving with a polyester solvent; melting to form a polyester melt; depolymerizing; and transesterifying. As shown in Figures 2 and 4, the modifying step may beperformed in a target polyester modifying zone 100 and may generate (i) product stream 105 that includes one or more target products and (ii) modification by-product stream 110 that may include any remaining contaminant modifying agents, contaminants and derivatives thereof. The modifying step may include in some embodiments a step of washing undissolved polyester with a wash solution (depicted as wash solution stream 104 in the Figures).

[0096] In some embodiments, target polyester may be washed with a wash solution, dissolved to form a solution or melted to form a melt; therefore, each may each be labeled or described as a “target” product. In non-limiting examples wherein the recovering step includes transesterifying polyester, target products may include copolyesters and modified polyesters. In nonlimiting examples wherein the recovering step includes depolymerizing polyester, target products may include polyester oligomers and monomers such as dimethyl terephthalate (“DMT”), dimethyl isophthalate (“DMI”), ethylene glycol (“EG”), 1 ,4-cyclohexanedimethanol (“CHDM”), 2, 2,4,4- tetramethylcyclobutane-1 ,3-dimethanol (“TMCD”), bis(2-Hydroxyethyl) terephthalate (BHET) and diethylene glycol.

[0097] One of ordinary skill may appreciate that, despite best efforts to remove contaminants, the product from the recovering step may include them, albeit in reduced amounts when compared to the feedstock. Accordingly, in one or more exemplary embodiments, the method of present invention may further comprise an optional step of treating the product of the recovering step with at least one contaminant modifying agent. Selection of the type and amount of contaminant modifying agent for optional treating step (d), as well the conditions for the step, may vary depending on a number of factors such as amount and type of contaminant, type of recovering step and type and form of target product. Such an optional step d) may be particularly advantageous for treatment of dyed chunk polyester, e.g., from extruder wastes, reactively dyed polyester, densified textiles, or re-extruded wastes wherein the contaminants are surrounded by a largely impenetrable polyester matrix.

[0098] In one non-limiting example, the target product may be a hydrophilic target product such as hydrophilic short chain esters, including for example predominately hydroxyl-end capped, glycol or glycol end-capped target products such as produced for example by glycolysis depolymerization and the like. Exemplary target products of this general class include bis(2-Hydroxyethyl) terephthalate (BHET) and BHEI (ethylene-glycol end-capped hydrophilic esters and oligomers of chain length less than about 4 repeat units of ethylene glycol and tere- and iso-phthalates). In non-limiting examples such as wherein polyesters such as polyethylene terephthalate (PET) may be depolymerized via glycolysis in the modifying step to produce a hydrophilic target product such as BHET, an optional treating step may include treating the product of the modifying step with a contaminant modifying agent that is hydrophobic or that includes a hydrophobic solvent or that includes a hydrophobic solvent for a contaminant. In general, “hydrophobic” is intended to describe and include materials that are immiscible in the recovering zone product under a given set of treating step conditions. Non-limiting examples of a hydrophobic solvents include generally aromatics ketones, for example one or more of C5 to C14 ketones, including a mix of C11 ketones commercially available from Eastman Chemical; more preferably C7-C12 ketones such as methyl propyl ketone (MPK), methyl amyl ketone (MAK), methyl isoamyl ketone (MIAK), di-isobutyl ketone (DIBK), methyl iso-butyl ketone (MIBK), di-isopropyl ketone (DIPK), methyl isopropyl ketone (MIPK) and combinations such as mixes of C7 or C9 ketones sold by Eastman Chemical; C6 to C13 aromatics such as naphthalenes, xylenes and mixed xylenes; aromatic fluids known in the art as Aromatic 150, Aromatic 200, Solvesso™ 150 and Solvesso™ 200 and sold commercially by Exxon Mobil™ and combinations; C6 to C14 alkanes, preferably C7 to C11 alkanes such as undecane; and isoparaffin fluids such as Isopar™ L. Mixtures of two or more hydrophobic contaminant modifying agents are also contemplated, including for example a mix of xylene and a C7 ketone; a mix of Aromatic 150 and a C7 to C9 ketone; and a mix of Aromatic 200 with a C9 ketone.

[0099] In embodiments where the target product is hydrophilic and the contaminant modifying agent is a hydrophobic contaminant modifying agent, the product from the optional modifying step may be a multi-phase product that includes a first phase which is hydrophilic and includes a hydrophilic target product and a second phase which is hydrophobic and includes a hydrophobic contaminant modifying agent and modified contaminant. The hydrophobic contaminant modifying agent may dissolve contaminant(s) while also extracting the dissolved contaminant(s) into a hydrophobic solvent phase of the multiphase product. Accordingly, in one or more exemplary embodiments, the optional treating step (d) may include extracting modified contaminant into a hydrophobic phase of a multi-phase treating zone product.[000100] In one or more exemplary embodiments and as depicted in Figures, the step of modifying target polyester may include depolymerizing the undissolved polyester in polyester modifying zone 100 to form product stream 105 that includes as target product(s) one or more polyester depolymerization products. In one or more embodiments, the step of recovering the undissolved polyester may include melting the undissolved polyester or dissolving the polyester to form a polyester melt or polyester solution and depolymerizing the polyester melt or solution. As one of ordinary skill will appreciate, the identity and amount of the polyester depolymerization products in product stream 105 will vary depending on for example the amount and identity of polyesters in the feedstock, the type of depolymerization reaction and depolymerization reaction conditions. Non-limiting examples of polyester depolymerization target products include polyester oligomers and monomers such as BHET, dimethyl terephthalate (“DMT”), ethylene glycol (“EG”), 1 ,4-cyclohexanedimethanol (“CHDM”) and diethylene glycol.[000101] In embodiments that may include depolymerizing polyester as the modifying step or as part of the modifying step, the depolymerizing step may be performed in the presence of one or more depolymerization catalysts (added to polyester recovering zone 100 as catalyst feed stream 101 in the Figures) and one or more depolymerization agent (added to polyester recovering zone100 as depolymerization agent stream 102 in the Figures). Depolymerization agents may include methanol, 2-ethylhexanol, polyol such as glycol, or a combination thereof. Depolymerization catalysts may include Mn, Zn salts, potassium and sodium carbonates, carboxylates (e.g., acetate), or aromatic carboxylates, e.g., sodium monomethylterephthalate, potassium and sodium alkoxides, e.g., sodum methoxide or potassium 2-ethylhexoxide and combinations thereof. In embodiments that include a depolymerization step or which otherwise relate to recovery of polyester monomers through depolymerization, the method of the present invention may be described or labeled as a method for method for decontaminating a contaminated polyester depolymerization feedstock; the contaminated polyester recovery feedstock may be described or labeled as a contaminated polyester depolymerization feedstock; the polyester recovering zone may be described or labeled as a polyester depolymerization zone; and the decontaminated polyester recovery feedstock may be described or labeled as a decontaminated polyester depolymerization feedstock.[000102] In embodiments that include depolymerizing as the modifying step or as a part of the modifying step, the depolymerizing step may include known polyester depolymerization methods, processes, mechanisms and systems such as methanolysis depolymerization; alcoholysis depolymerization, e.g., using 2-ethylhexanol as the depolymerizing agent; glycolysis depolymerization, for example to form or recover target product bis(2-Hydroxyethyl) terephthalate (BHET); pyrolysis depolymerization; hydrolysis depolymerization; and hydrogenolysis depolymerization. Suitable glycolysis methods are described for example in U.S. Pat. Nos. 3,257,335; 3,907,868; 6,706,843; and 7,462,649, the contents and disclosure of which have been incorporated herein by reference. Suitable methanolysis methods are described for example in U.S. Pat. Nos. 3,037,050; 3,321 ,510; 3,776,945; 5,051 ,528; 5,298,530; 5,414,022; 5,432,203; 5,576,456 and 6,262,294, the contents and disclosure of which have been incorporated herein by reference. The step forms a depolymerization product stream that may include target product and residual contaminant(s).Target product generally includes any monomer or oligomer generated by depolymerization of polyester may be exemplified by one or more of polyester oligomers, dimethyl terephthalate (“DMT”), ethylene glycol (“EG”), 1 ,4- cyclohexanedimethanol (“CHDM”) and diethylene glycol. In brief, hydrogenolysis depolymerization includes reacting hydrogen with polyester, typically in the presence of a catalyst such as a transition metal catalyst, to reduce ester bonds in the polyester to alcohols and form target products that may include 1 ,4-phenylenedimethanol or similar 1 ,3- or 1 ,2- phenylenedimethanol isomers.[000103] In one or more exemplary embodiments, the modifying step may include transesterifying polyester in the feedstock to form a modified polyester. In such steps the polyester includes one or more polyols or glycols that are substituted with or displaced by one or more substitute polylols or glycols, with the substitute polyols or glycols substituting or displacing all or part of the initial polyol or glycol to form a modified polyester. In brief, the process of transesterifying is initiated by heating and mixing of the initial polyester, a transesterification catalyst, preferably Ti, Mn, Co, or Zn-based containing catalysts, and one or more transesterifying agents (shown as 103 in the Figures) such as substitute polyols or glycols, and is accompanied by simultaneous evaporation or distillation of said initial polyols or glycols to drive the reaction, maintain or increase polyester molecular weight, produce removed polyols and glycols, and to form a modified polyester that may be a polyester. To enable the simultaneous distillation and transesterification, it is necessary that the substitute polyols or glycols have either a higher boiling point (lower vapor pressure) than the initial polyols or glycols targeted for removal, or said initial polyols or glycols form a low-boiling azeotrope with an added glycol stripping agent. In one embodiment, the initial polyester comprises ethylene glycol as the initial glycol, and is transesterified with the substitute glycol of cis / trans-1 ,4-CHDM, producing ethylene glycol as the removed glycol. In one or more embodiments the removed glycol is ethylene glycol. In one or more embodiments, the modified polyester is a copolyester. In one or moreembodiments, the modified polyester is a copolyester comprising 1 ,4-CHDM or 1 ,3-CHDM or combinations therein. In one or more embodiments, the modified polyester is a copolyester comprising neopentyl glycol, 2- Methyl- 1 ,3- Propanediol (hereafter MP diol), 1 ,4-CHDM or 1 ,3-CHDM or combinations therein. In one or more embodiments the added glycol stripping agent forms a low-boiling heterogeneous azeotrope with the removed glycol, such as ethylene glycol. In one or more embodiments the added glycol stripping agent may be a C7 to C12 aromatic, a C7 to C14 alkane, a C7 to C11 ketone or a combination thereof.[000104] In one or more exemplary embodiments, the recovering step may include washing target polyester with a polyester wash solution. The polyester wash solution may at least partially remove residual materials. The wash solution may include one or more contaminant modifying agents. The polyester wash solution typically is fed at a polyester precipitate / wash solution ratio of 0.25 / 1 to 6 / 1 , more typically 0.75 / 1 to 3 / 1 or 0.5 / 1 to 2 / 1. The washing may include displacement washing wherein the wash solution displaces interstitial liquid in a plug flow manner or may involve dilution washing wherein the wash solution combines with the undissolved polyester to form a slurry or other flowable form which may be transferrable to another vessel for further processing.[000105] The following examples, while provided to illustrate with specificity and detail the many aspects and advantages of the present invention, are not to be interpreted as in any way limiting its scope. Variations, modifications and adaptations which do depart of the spirit of the present invention will be readily appreciated by one of ordinary skill in the art. Table numbering for data tables is intended to match corresponding example numbering. As some examples do not include a data table, data table numbers are therefore not necessarily sequential.[000106] Analytical Methods[000107] GC hydrolysis method for PET content[000108] In this analytical method, polymeric ester linkages are hydrolyzed under basic conditions to constituent glycol (EG, DEG, CHDM) and diacid monomers (terephthalic and isophthalic acids). The resulting monomers are then acidified and derivatized for analysis by gas chromatography. Samples were prepared by weighing 0.11 to 0.14 grams of sample into a 20-mL screwtop headspace vial and then adding 0.4 to 0.5 grams of KOH pellets (>85% purity) and a magnetic stir bar. An Eppendorf automatic dispensing pipette (or equivalent) was used to accurately add 5.0-mL of internal standard solution consisting of tridecane and suberic acid in n-propanol and n-methylpyrrolidone. The headspace vial was then heated and stirred for 25 minutes at 95°C. The vial was removed and allowed to cool to room temperature, and then 5.0-mL of acidified pyridine was added using the automatic dispensing pipette. The vial was thoroughly vortexed, the solid salts were allowed to settle, and 100 pL of the supernatant was added to an autosampler vial. Next, 500 pL of BSTFA was added, and the autosampler vial was heated to 80°C for 10 minutes. Once prepared, samples were chromatographed on a 30m x O.32mmlD x 0.25 micron (5%-Phenyl)-methylpolysiloxane column using temperature programming and flame ionization detection. Multipoint calibrations were performed by taking pure monomer standards of terephthalic acid, isophthalic acid, ethylene glycol, diethylene glycol, and CHDM, through the entire sample preparation, with acceptable coefficients of determination exceeding 0.999. Any non-polyester material is not hydrolyzed to glycol or diacid monomers and thus will not show up in the GC analysis. The calibrated reported weight percentages of glycol and diacid moieties may sum to greater than 100% because the hydrolyzed monomers include the mass of the water of hydrolysis as compared to the esterified monomers in the starting polymer. For example, a 100% polyester comprising EG and TPA monomers would give a result of 32.3 wt% EG and 86.5 wt% TPA.[000109] Example analysis[000110] A fabric sample from a blue lab coat (80 / 20 polyester / cotton blend per the label on the coat) was analyzed by GC hydrolysis to determine actualpolyester weight fraction of the sample. GC hydrolysis results and calculation of polyester content are summarized in Table E below. Using an arbitrary basis of 1.0 gram of lab coat, monomer weight percents were calculated using experimental GC hydrolysis (column 2 top section, Table E) and converted to give monomer masses (column 3 top section). The masses were converted to moles of monomers (column 4 top section) by dividing by monomer molecular masses (column 1 top section). Moles of monomers were converted to moles of theoretical polyester repeat units assuming statistical distribution of repeat units (column 4 bottom). The mass of each repeat unit present (column 3 bottom section) in the sample was found by multiplying moles of repeat units by repeat unit molar masses (column 1 bottom section). Summation of repeat unit masses provided the total polyester mass in the original lab coat sample, with the mass of non-polyester contaminants determined as the original sample mass minus the polyester mass. This analysis indicated that the lab coat comprised 73.2 wt% polyester and 26.8 wt% of cotton, dyes, and other nonpolyester additives. The garment label suggested that the sample contained 18.3 wt% cotton (PET / cotton in 80 / 20 weight ratio and 8.5% dyes and other non-polyester materials. The lab coat sample and the analysis was used in Example 13.TABLE ETABLE E[000111] Chlorine analysis by CIC method[000112] Samples were analyzed on a Combustion Ion Chromatograph (CIC) instrument. The samples are oxidized by pyrohydrolytic combustion at temperatures <1000C. Halogens present are converted to their anions F-, Cl-,Br-. A gas stream carries the analytes to the absorber medium. An aliquot of the absorber solution is then injected into the Ion Chromatograph (IC) The halide anions are then separated and quantified using a pre calibrated thermal conductivity detector.[000113] Examples[000114] Control (Counterexample) 1 : Solution Density required for PET and PVC to sink or float in the absence of PVC contaminant modification [000115] In this example various aqueous salts were tested to determine at what solution densities unmodified PET and PVC flakes floated or sank. Five grams of either post-consumer PET bottle flake or PVC packaging flake (average flake dimensions of 3 to 5 mm) were added to a glass beaker containing 50 grams of the specified salt solution at 25°C. The mixture was stirred vigorously for 30 seconds using a spatula, then allowed to settle for 10 minutes. At the end of the hold time, the mixture was examined to determine if the plastic content sank or floated. In all cases the vast majority of plastic content either floated or sank (typically only a few particles deviated from the majority behavior), so designation of “float” or “sink” was unambiguous. N / A in the data table signifies that a solution of the specified density could not be made with the particular salt at 25°C. Results of the testing are given in Table 1. These examples show that all salts of equivalent densities acted similarly and that a simple density difference could not be used to separate PET and unmodified PVC, as PET and PVC acted the same in all cases (both plastics either sank or floated in all salt-density combinations).TABLE 1TABLE 1[000116] Example 2: Separation of PVC / PET mixture with modification (swelling) of PVC[000117] In this example, the effect of contaminant modifying agent exposure on the sink / float behavior of PVC and PET was examined. Five grams of either post-consumer PET bottle flake or PVC packaging flake (average flake dimensions of 3 to 5 mm) were added to 30 grams of various contaminant modifying agents and allowed to soak for 10 minutes at 25°C in the modifying agent. The free excess contaminant modifying agent was drained off the plastic sample and the treated sample containing modified (swelled) PVC or PET was added to a glass beaker containing 50 grams of potassium acetate (KOAc) solutions of specified densities at 25°C. The mixture was stirred vigorously for 30 seconds using a spatula, then allowed to settle for 10 minutes. At the end of the hold time, the mixture was examined to determine if the plastic content sank or floated. In all cases the vast majority of plastic content either floated or sank (typically only a few particles deviated from the majority behavior), so designation of “float” or “sink” was unambiguous. Results of the testing are given in Table 2. These examples shows that the density of PVC treated with contaminant modifying agent that caused swelling of the PVC significantly altered the density of the modified PVC, and said modified PVC floated in lower density salt solutions than in Counterexample 1. In contrast, PET was unaffected by exposure to contaminant modifying agent and sank in salt solutions of all densities tested as in Counterexample 1 , thus allowing for sink / float density separation of modified PVC and PET.TABLE 2= counterexample[000118] (Control) Counterexample 3: Sink / float testing of PVC / PET mixture without modification of PVC contaminant[000119] 165.05 grams of reclaimer reject flake, comprising 95.1 wt% PET and4.9 wt% PVC, was added at room temperature (about 20°C) to a 5-liter polyethylene flat-bottomed tub containing 4000 grams of of a 37.97 wt% solution of potassium acetate in water (density of 1 .2 grams / ml of solution). The tub contents were manually agitated back and forth with a spatula for 1 minute.Agitation was stopped and the tub contents were allowed to stand for 5 minutes. During this quiescent time, essentially all the solid particles sank to the bottom of the tub. A few individual particles floated (approximately 0.1 to 0.2 grams total mass). No separation of PVC and PET occurred.[000120] Example 4: Separation of PVC / PET mixture with modification (swelling) of PVC[000121] 165.05 grams of reclaimer reject flake, comprising 95.1 wt% PET and 4.9 wt% PVC, was added at room temperature (about 20°C) to a 5-liter polyethylene flat-bottomed tub containing 4000 grams of a 38 wt% solution of potassium acetate in water (density of 1.2 grams / ml of solution). 50 grams of a contaminant modifyting agent (acetone) were added to the solution / flake mixture and the tub contents were manually agitated back and forth with a spatula for 1 minute. Agitation was stopped and the tub contents were allowed to stand for 5 minutes. During this quiescent time, most of the solid particles sank to the bottom of the tub and a small fraction of the solid particles floated on the surface of the liquid. The solid particles floating on the surface of the solution were removed using a 7.6-cm diameter strainer. The contaminant modifying agent addition (50 grams each time), agitation, quiescent hold, and removal of floating particles was repeated two more times. Each of the three batches of floating particle were washed with 50 grams of demineralized water and dried overnight in a vacuum oven held at 60°C. The dried solids were manually separated into modified PVC and PET fractions (PVC fluoresced bluish purple in UV light, while PET showed no change in color) and weighed for mass balance. Results of each swell / float / skimming cycle are listed below in Table 4.TABLE 4[000122] Example 5: Modification of non-Polyester Contaminants[000123] In this example, non-polyester contaminants and polyester were tested individually to determine the modification mechanism ( dissolved, swelled, or reacted) for a variety of contaminant modifying agents as well as investigate any effect on polyester. A description of each non-polyester contaminant and the test polyester (PET) are given in Table 5. In each test 1 gram of PET or contaminant was added to a glass vial or Fischer-Porter bottle with 20 grams of solvent. The mixture was then ramped up in temperature from 20°C in 5 to 10°C increments to determine at what temperature the PET or contaminant dissolved (solubilized), swelled, melted / floated (i.e., became a liquid and phase separated from solvent), or reacted. The temperature ramp was discontinued at 220°C or at a temperature corresponding to a solvent vapor pressure of 3.45 bara if nothing happened at lower temperatures. The following solvents were tested with each non-polyester contaminant and PET: toluene, xylenes, A150 (consists predominately of C9-C11 aromatic hydrocarbons), solvesso 150, heptane, decane isomers, isopar L, MPK, MIBK, MAK, MIAK, DIBK, cyclohexanone, mixed C1 1 ketones, iso and n-propyl acetate, butyl acetate, methanol, iso and n-propanol, iso and n-butanol, 2-ethylhexanol, EG, DEG, TEG, NMP, NBP, DMAC, dimethylpropamide, 1 ,3-Dimethyl-2- imidazolidinone, butoxyDEG, butoxyethanol, DMT, DMI, methyl benzoate, methyl p-toluate, benzyl alcohol, 4-methylbenzyl alcohol, acetic acid, propionic acid, acetic acid / CaCI2, acetic acid / CaTriflate, methanol / CaCI2, MeOH / Catriflate. Results of the test protocol are summarized in Tables B-1 to B-9, Table C, and Table D.TABLE 5: Test Material Description of Non-Polyester Contaminants and PET[000124] Example 6: Dissolution of dye and elastane from dyed polyester / elastane fabric swatch[000125] In this example a swatch of 1.1126 grams of bright pink elastane- PET fabric was cut from a pair of leggings purchased at a department store. The fabric was analyzed by the hydrolysis method and found to contain 83.4 wt% PET. The swatch was placed in a glass vial with 15 grams of a contaminant modifying agent (2-heptanone) . The vial was purged with N2, sealed and heated to 130°C for two hours. Both pink dye and parts of the fabric swatch were observed to dissolve in the 2-heptanone. At the end of the hold time, the contaminant modifying agent was filtered off the treated fabric matrix, and the treated matrix washed twice with 3 grams of acetone to remove any residual contaminant modifying agent and dissolved components. The now white treated fabric matrix was dried in a vacuum oven at 50°C overnight. The dried treated fabric matrix weighed 0.892 grams. The treated matrix was found to contain 99.8% PET by GC hydrolysis, for a recovery of 92.8% of the original PET content.[000126] Example 7: Separation of PVC / PET mixture with modification (dissolution) of PVC In this example post-consumer bottle flake was mixed with shredded PVC packaging film to create mixtures of PET / PVC with between 100 to 10,000 ppm of chlorine content. The PVC used in this test was found to comprise 54.5 wt% chlorine by the CIC method. Approximately 500 grams of the PET / PVC mixture was added into an agitated 5-liter jacketed glass vessel containing roughly 1500 grams of contaminant modifying agent (2-pentanone, MPK) heated to 80°C. The mixture was stirred at temperature for % hour, then the resulting slurry was filtered on a Buchner funnel. The solids on the funnel were washed with warm (40°C) 2-pentanone (roughly 500 grams) and the combined filtrates analyzed for chlorine content to determine PVC removal efficiency. Starting masses, sample weights, Cl results, dried mass, calculated PVC removal efficiency, PET recovery are given in Table 7.TABLE 7[000127] Example 8: Dye removal from PET shirt fabric by dipping treatment with contaminant modifying agent A150 r[000128] A dark Navy blue shirt was analyzed by GC hydrolysis method to determine PET content, which was found to be 93.4 wt%, with an expected dye content of 3-6 wt% as specified by the manufacturer. A small portion of theshirt (0.43 grams) was dipped successively in 5 vials containing 5 grams each of A150 (commercially available solvent consisting predominately of C9-C11 aromatic hydrocarbons) (held one minute in a vial, pulled out, then placed in the next vial), each held at 150°C. After fabric immersion, the liquid left in the first vial was observed to be deep blue, with successively lighter color in the series and essentially no observed color in the final vial. The treated fabric portion was white, with no hint of blue color. The liquid in the vials were combined together and the sample evaporated in a vacuum oven held at 100°C, 0.06 bara overnight. The deep, deep blue residual from the solvent evaporation was found to weigh 0.02752 grams (6.4 wt% of the original fabric portion). The treated white fabric was rinsed in acetone and dried overnight in a vacuum oven, with a post drying weight of 0.3995 grams. The dried treated white fabric was analyzed by GC hydrolysis and found to be 99.4% PET.[000129] Example 9: Removal of Red dye contaminant from dyed polyester sample[000130] This example illustrates methods for enhanced treatment of polyesters containing red dye contaminants. A dark red polyester shirt material, nominally 96.6 wt% PET by GC hydrolysis, was cut into 1 cm square swatches. Approximately 10 grams of swatches were placed in each of two Fisher-Porter bottles. 100 grams of contaminant modifying agent (m-xylene) was added to one bottle, and 90 grams of contaminant modifying agent including a mixture of m-xylene with 10 grams of ethylene glycol was added to the second bottle. The bottles were purged with nitrogen, sealed and heated to 180°C for 2 hours. At the end of the two hours the solvents were drained off, each treated polyester was washed with 30 grams of m-xylene, then 30 grams of acetone. The acetone-wet treated samples were dried in a vacuum oven overnight at 50°C. Both dried, treated samples lost about 5 wt% of the initial untreated weight, however the m-xylene- treated sample was pink to light red, while the m- xylene / EG treated sample was white with no hint of red color.[000131] Example 10: Dye removal from polyester (PET) shirt fabric by dipping in contaminant modifying agent[000132] Additional contaminant modifying agents were tested in a procedure similar to Example 7 to determine efficacy of contaminant dye removal. Small portions (about 0.4 grams each) of dark red, dark blue, white, black, orange, sky blue PET shirt fabrics (nominally about 93-95% PET by GC hydrolysis) and one portion of black 80 / 20 wt% PET / cotton blend were dipped in and held for 1 minute in 5 successive vials of contaminant modifying agent (about 5 grams each) held at 10°C below the normal boiling point of the contaminant modifying agent. For the 90 / 10 wt% xylene / EG contaminant modifying agent mixture, the treatment was done at 170°C, under pressure in series of Fischer-Porter bottles. Results are given in Table 9, identifying the vial number where color disappeared in the contaminant modifying agent (or the color of the fifth vial if still colored) and the color of treated fabric.TABLE 10TABLE 10Black 1 = polyesterBlack 2 = polyester / cotton 80 / 20[000133] Example 11 : Separation of dye and Nylon-6, 6 from polyester blend fabric swatch via dissolution of contaminants[000134] In this example a swatch of 2.0 grams of multi-colored (blue, red, yellow, black) Nylon-6, 6 / PET fabric was cut from a pair of leggings purchasedat a department store. The label indicated the fabric to be 20 / 80% nylon / PET. The fabric was analyzed by the GC hydrolysis method and found to contain 78.2% wt% PET content. The swatch was placed in a glass vial with 30 grams of contaminant modifying agent (acetic acid / Calcium triflate salt (10 wt% salt)). The vial was purged with N2, sealed and heated to 110°C for three hours. Both dyes and parts of the fabric swatch were observed to dissolve in the contaminant modifying agent. At the end of the hold time, the contaminant modifying agent was filtered off the treated fabric matrix, and the treated matrix washed first with 6 grams of acetic acid, then 6 grams of acetone to remove any residual contaminant modifying agent and dissolved components. The now- white treated fabric matrix was dried in a vacuum oven at 50°C overnight. The dried treated fabric matrix weighed 1 .45 grams. The treated matrix was found to contain 98.0% PET by GC hydrolysis, for a recovery of 90.7% of the original PET content.[000135] Example 12: Separation of polyolefin (PO, polyethylene) contaminant from polyethylene / polyester mixture[000136] This example illustrates the removal of contaminant polyethylene from a polyester / polyethylene mixture comprising shredded post-consumer polyester bottles. 5 bottles from a collection of 50 identical 355 ml postconsumer water bottles (labels removed and air dried to visually contain no liquids) were weighed with and without caps present to determine wt% PET (bottle) and polyethylene (caps). The average bottle and cap weight was 13.6026 grams, and 11.7616 grams without the cap (NOTE: caps were green in color, bottles were clear), for an average composition of 13.5 wt% polyethylene and 86.5 wt% PET. The other 45 bottles were shredded to an average particle size of 5-8 mm in length. For each test, approximately 10 grams of the shredded feedstock and 90 grams of contaminant modifying agent were loaded into Fischer-porter bottles, sealed, heated, and held for two hours. At the end of the hold time, the remaining solids were filtered hot. The filtrate was evaporated to dryness, with the green residue weighed. The treatedpolyester was washed off with acetone, dried in a vacuum oven overnight at 80°C, and weighed. For the case with EG as the contaminant modifying agent, the dissolved polyethylene layer was scooped off the top of the EG mass prior to filtration of the treated sample. Initial masses, treatment temperatures, dry weights, and calculated recoveries are given in Table 12.TABLE 12[000137] Example 13: Separation of contaminants from dyed cotton / polyester fabric with subsequent glycolysis / methanolysis of remaining polyester to recover dimethyl terephthalate (DMT)[000138] 10 grams of a blue polyester / cotton lab coat sample described above and in Table E (73.2 wt% polyester and 18.3 wt% of cotton, 8.5 wt% dyes and other non-polyester additives) was treated with a contaminant modifying aqent comprising a mixture of 90 / 10 wt / wt ratio of xylene / EG. The lab coat (10 grams) and 100 grams of contaminant modifying aqent were placed in a Fischer-Porter bottle and heated to 185°C for 2 hours. At the end of the hold time the deep blue colored, contaminant modifying aqent solution was filtered off and a polyester-containing depolymerization feedstock was isolated. The feedstock was added to a stirred glass reactor containing 20 grams of ethylene glycol and 0.03 grams of potassium carbonate. This mixture was heated to 190°C for 2 hours to glycolyze the polyester content of the feedstock. The remnants of the cotton fabric matrix was picked out of the hot mixture with a spatula and washed with 10 grams of methanol to recover additional glycolysis materials. The washmethanol and solids-free glycolysis mixture was added to another stirred glass vessel, along with 0.025 grams of 50 wt% aqueous caustic, and heated to 60°C for 30 minutes. The resulting solid DMT target product was cooled to room temperature, filtered, and washed with 10 grams of methanol. The vacuum oven dried, the resulting DMT target product weighed 6.58 grams. The resulting DMT target product was bright white in color, with a melt point of 140.2°C (reported pure component melt point of 140.6°C) and the yield of DMT was 91.3% of theoretical.[000139] Control (Counterexample) 14: Glycolysis / Methanolysis of dyed cotton / polyester fabric feedstock without contaminant modifying agent pretreatment[000140] The glycolysis / methanolysis procedure of Example 13 was repeated identically except that the contaminant modifying agent pretreatment step was omitted. The resulting DMT target product was brown in color with a melt point of 135°C and the yield of DMT was 85% of theoretical.[000141] Example 15: Separation of contaminants from dyed polyester metal- contaminated mixture (extruder reject) with subsequent glycolysis / methanolysis of remaining polyester to recover dimethyl terephthalate (DMT)[000142] A green-colored extruder reject polyester mixture was analyzed by GC hydrolysis and determined to be 98.1 wt% polyester. 10 grams of this material was treated with a 100 grams of contaminant modifying agent comprising a mixture of 90 / 10 wt / wt ratio of xylene / EG, by heating to 185°C for 2 hours. At the end of the hold time a green contaminant modifying agent solution was filtered off and a polyester-containing depolymerization feedstock was isolated. The feedstock was added to a stirred glass reactor containing 20 grams of ethylene glycol and 0.03 grams of potassium carbonate. This mixture was heated to 190°C for 2 hours to glycolyze the polyester content of the feedstock. The glycolysis effluent was filtered to remove small pieces of metalcontaminants and other unknown contaminants. The filtered glycolysis effluent was added to another stirred glass vessel, along with 10 grams of methanol and 0.025 grams of 50 wt% aqueous caustic, and heated to 60°C for 30 minutes. The resulting solid DMT target product was cooled to room temperature, filtered, and washed with 10 grams of methanol. The vacuum oven dried, the resulting DMT target product weighed 7.9 grams. The resulting DMT target product was bright white in color, with a melt point of 140. °C (reported pure component melt point of 140.6°C) and the yield of DMT was 82% of theoretical.[000143] Control (Counterexample) 16: Glycolysis / Methanolysis of extruder reject mixture without contaminant modifying agent pretreatment[000144] The glycolysis / methanolysis procedure of Example 15 was repeated identically except that the contaminant modifying agent pretreatment step was omitted. The resulting DMT target product was brownish green in color with a melt point of 137°C and the yield of DMT was 81 % of theoretical.[000145] Example 17: Separation of contaminants from mixed multisource polyester materials with subsequent glycolysis / methanolysis of remaining polyester to recover dimethyl terephthalate (DMT)[000146] A mixture of post-consumer polyester-containing materials comprising dyed multi-color PET / cotton, PET / nylon, PET / spandex fabrics, bottle polymer, reclaimer reject flakes containing PVC and polyolefins was analyzed by GC hydrolysis and determined to be 85.3 wt% polyester. 100 grams of this mixture was treated with the contaminant modifying agents listed in Table 17 (300 grams each). In each case the mixture was treated by immersion in the contaminant modifying agent at the indicated in Table 17 temperature for 2 hrs, filtered, washed with acetone, and dried to form a depolymerization feedstock.. The feedstock was added to a stirred glass reactor containing 200 grams of ethylene glycol and 0.3 grams of potassium carbonate. This mixture was heated to 190°C for 2 hours to glycolyze thepolyester content of the feedstock. The glycolysis effluent was filtered to remove small pieces of metal and other unsolubilized contaminants. The filtered glycolysis effluent was added to another stirred glass vessel, along with 100 grams of methanol and 0.25 grams of 50 wt% aqueous caustic, and heated to 60°C for 30 minutes. The resulting solid DMT target product was cooled to room temperature, filtered, and washed with 100 grams of methanol. The vacuum oven dried, the resulting DMT target product weighed 75 grams. The resulting DMT target product was off white in color, with a melt point of 140.1 °C (reported pure component melt point of 140.6°C) and the yield of DMT was 89.3% of theoretical.TABLE 17[000147] Control (Counterexample) 18: Glycolysis / Methanolysis of mixed multisource polyester materials without contaminant modifying agent pretreatment.[000148] The glycolysis / methanolysis procedure of Example 17 was repeated identically except that the contaminant modifying agent pretreatment step was omitted. The glycolysis effluent mixture was very slow to filter. The resulting DMT target product was dark brown in color with a melt point of 133°C and the yield of DMT was 87% of theoretical.[000149] While this aspect of the method of present invention has been described in a particular sequence of steps (e.g., treating, separating, recovering, modifying), one of ordinary skill will appreciate that the method of the present is not necessarily limited to a specified method step sequence and that other sequences are contemplated and are within the spirit and scope of the invention. In one non-limiting example, the method may include a polyesterrecovering step subsequent to the treating step but preceding the separating step. Accordingly, in one or exemplary embodiments, the method may include for example treating in a treating zone a contaminated polyester recovery feedstock with a liquid contaminant modifying agent in which said polyester is substantially insoluble to form at least one modified contaminant and undissolved polyester in a carrier liquid; recovering the undissolved polyester in a polyester recovering zone to form a product stream comprising (i) polyester target product and optionally (ii) residual contaminants; and optionally separating modified contaminant in a separating zone. In another non-limiting example, the method may include a polyester recovering step preceding optional treating and separating steps. Accordingly, in one or more exemplary embodiments, the method may include dissolving polyester from a contaminated polyester recovery feedstock in a recovering zone to form a recovery product comprising (i) dissolved polyester and contaminants; separating dissolved polyester product from the recovery product; optionally precipitating dissolved polyester to form polyester precipitate; and optionally depolymerizing or transesterifying dissolved polyester or polyester precipitate. [000150] While zones such as the treating zone, separating zone and recovering zone and purifying zone are depicted as spatially separate in the Figures for convenience, one of ordinary skill will appreciate that treating, separating, purifying and recovering functions with the methods and systems of the present invention may overlap. For example, treating zone may include some amounts or all of a separating function. Similarly, some amount of a contaminant treating function to form modified contaminant may occur in separating zone. Indeed, in one or more embodiments, separating zone may, as a spatial arrangement matter, overlap with or be partially or wholly contained within a treating zone. Further, in one or more embodiments, separating zone, treating zone and recovering zone may, as a spatial arrangement matter, overlap with or be partially or wholly contained within each other. In some embodiments, therefore, the method may be described as batch, insofar as treating, separating and recovering steps are performed sequentially in asingular zone or sequentially in a singular vessel. In some embodiments, the method may be described as semi-continuous or continuous insofar as treating, separating steps and recovering steps may be performed at least partially in separate zones or vessels.[000151] The present invention is described herein with respect to various interrelated aspects and embodiments and one of ordinary skill will understand and appreciate that elements or features used to describe one aspect or embodiment may be applicable and useful in describing other embodiments. Accordingly, descriptions and disclosure relating to elements or features of an aspect or embodiment of the present invention are hereby expressly relied on to describe and support those elements or features in other aspects or embodiments. More particularly, descriptions and disclosure relating to elements or features of the method for decontaminating a polyester recovery feedstock as described herein are hereby expressly relied on to describe and support those elements or features in the method for recovering a polyester from a contaminated polyester recovery feedstock as described herein, and vice versa.[000152] The foregoing description of various embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Numerous modifications or variations are possible in light of the above teachings. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

THAT WHICH IS CLAIMED IS:

1. A method for recovering polyester from a contaminated polyester recovery feedstock comprising polyester and one or more contaminants, said method comprising the steps of (a) treating contaminated polyester recovery feedstock with a contaminant modifying agent in which said polyester is substantially insoluble to form a treating zone product including at least one modified contaminant and undissolved polyester; (b) separating at least one of the modified contaminant and the undissolved polyester from the treating zone product to form a decontaminated polyester recovery product that includes undissolved polyester; and optionally (c) recovering the undissolved polyester to form a refined polyester recovery product comprising (i) target polyester and optionally (ii) residual contaminants.

2. The method of claim 1 wherein said treating step (a) comprises swelling at least one contaminant to form a treating zone product comprising at least one swelled contaminant solids and undissolved polyester.

3. The method of claim 1 wherein said treating step (a) comprises reacting at least one contaminant with said contaminant modifying agent to form a treating zone product comprising at least one contaminant reaction product solids and undissolved polyester.

4. The method of claim 1 wherein said treating step (a) comprises melting at least one contaminant in the presence of a contaminant modifying agent to form a multiphase treating zone product comprising a contaminant melt phase, a contaminant modifying agent phase and undissolved polyester.

5. The method of claim 1 wherein said one or more contaminants comprises cellulosics and wherein said treating step comprises include swelling said cellulosics with swelling agent to form swelled cellulosic solids and reactingswelled cellulosic solids with an anhydride contaminant reacting agent in the presence of acid catalyst to convert the cellulose to a cellulose ester.

6. The method of claim 5 wherein said swelling agent comprises acetic acid.

7. The method of claim 5 wherein said anhydride contaminant reacting agent comprises acetic anhydride.

8. The method of claim 5 wherein said acid catalyst comprises sulfuric acid.

9. The method of claim 1 wherein said contaminant modifying agent comprises a solvent for said contaminant and said treating step (a) comprises solubilizing said contaminant to form a treating zone product comprising at least one solubilized contaminant and undissolved polyester.

10. The method of claim 9 wherein said at least one contaminant comprises one or more of dye, PVC, cellulosics and polyolefin.11 . The method of claim 10 wherein said at least one contaminant comprises dye.

12. The method of claim 11 wherein said solvent is selected from the group consisting of C1 -C8 secondary and tertiary amides; C1-C10 secondary and tertiary lactams and cyclic amides.

13. The method of claim 11 wherein said solvent comprises one or more of N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone, N-butyl-2-pyrrolidone, dimethylacetamide, diethylacetamide, dimethyl propanamide, dimethyl butanamide, dimethylformamide, diethylformamide, 1 ,3-Dimethyl-2-imidazolidinone.

14. The method of claim 5 wherein said solvent further comprises a glycol.

15. The method of claim 9 wherein said treating step is performed at a temperature of 1 10°C to 150°C.

16. The method of claim 15 wherein said treating step is performed at a temperature of 125°C to 140°C.

17. The method of claim 3 wherein said one or more contaminants comprises PVC and wherein the treating step includes decomposing PVC to form HCI and a decomposed polyunsaturated PVC backbone and neutralizing said HCI with a neutralizing species to form a neutralized chlorine salt in said treating zone product.

18. The method of claim 3 wherein said one or more contaminants comprises polyolefin and wherein said treating step the comprises melting said contaminant in the presence of a contaminant modifying agent to form a multiphase treating zone product comprising a polyolefin melt phase, a contaminant modifying agent phase and undissolved polyester.

19. The method of claim 18 wherein said method or said separating step further comprises separating said polyolefin melt phase from said contaminant modifying agent phase.

20. The method of claim 17 wherein said method or said separating step further comprises separating the neutralized chlorine salt from said treating zone product.

21. The method of claim 5 wherein said method or said separating step further comprises separating said cellulose ester from said treating zone product.

22. The method of claim 1 wherein said method or said separating step comprises separating said undissolved polyester from said treating zone product.

23. The method of claim 1 wherein said feedstock and said treating zone product further include insoluble contaminant.

24. The method of claim 1 further including depolymerizing said target polyester to form target product.

25. The method of claim 15 wherein said depolymerizing step comprises hydrogenolysis.

26. The method of claim 1 further including transesterifying said target polyester to form target product.

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