Ethylene glycol and terephthalic acid recovery from polyethylene terephthalate deconstruction processes

Abstract

The present disclosure relates to methods designed for the depolymerization of poly(ethylene terephthalate) (PET) and the subsequent recovery and reuse of the PET deconstruction products. Among other things, the present disclosure describes methods for generating enriched reaction media, where the method includes providing a first amount of PET to a reaction chamber, performing depolymerization of the PET, thereby generating a first reaction media, adding a second amount of PET to the first reaction media, and performing depolymerization on the combined second amount of PET and the first reaction media, thereby generating an enriched hydrolysis reaction media, thereby enabling improved downstream separation of the deconstruction products.

Description

[0001] ETHYLENE GLYCOLAND TEREPHTHALIC ACID RECOVERY FROM POLYETHYLENE TEREPHTHALATE DECONSTRUCTION PROCESSES CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S Provisional Application Nos. 63 / 642,940 and 63 / 668,257 filed May 6, 2024 and July 7, 2024, respectively, the contents of which are incorporated herein by reference in their entirety.

[0003] CONTRACTUAL ORIGIN

[0004] This invention was made with government support under Contract No. DE-AC36-08GO28308 awarded by the Department of Energy. The government has certain rights in the invention.

[0005] FIELD OF INVENTION

[0006] The present disclosure relates to methods aimed at the deconstruction of polyethylene terephthalate and the recovery and separation of the resultant deconstruction products.

[0007] BACKGROUND

[0008] Polyethylene terephthalate) (PET) is a ubiquitous polyester, with applications across many industries, including textiles and packaging. Present estimates suggest that of the 359 million tons of plastics produced annually worldwide, 150-200 million tons accumulate in landfills or in the natural environment. PET is the most abundant polyester plastic, with almost 70 million tons manufactured annually worldwide. While processes exist for recycling PET, these processes are often detrimental to the environment in one or more ways. Thus, there remains a need for methods that transform recovered, end-of-life PET products into useful, environmentally friendly, and economical second-generation intermediates and products.

[0009] SUMMARY

[0010] In one aspect of the present disclosure, a method for generating enriched reaction media is provided. The method includes providing a first amount of poly(ethylene terephthalate) (PET) to a reaction chamber. The method also includes performing depolymerization of the PET, thereby generating a first reaction media. Additionally, the method includes adding a second amount of PET to the first reaction media. The method further includes performing depolymerization on the combined second amount of PET and the first reaction media, thereby generating an enriched hydrolysis reaction media.

[0011] In some embodiments of the present disclosure, depolymerization of the PET generates ethylene glycol (EG), terephthalic acid (TP A), and / or oligomers of EG and / or TPA. In some embodiments of the present disclosure, the combined second amount of PET and first reaction media may be provided to the reaction chamber. In some embodiments of the present disclosure, the method may include a fed-batch process within the reaction chamber. In some embodiments of the present disclosure, the combined second amount of PET and reaction media may be combined prior to being provided to the reaction chamber. In some embodiments of the present disclosure, the combined second amount of PET and the reaction media may be combined after being provided separately to the reaction chamber.

[0012] In some embodiments of the present disclosure, the depolymerization of the PET may include at least one of an enzymatic hydrolysis process, a chemical deconstruction process, a thermal deconstruction process, or a combination thereof. In some embodiments of the present disclosure, an enzymatic hydrolysis process may include providing one or more enzymes to the enzyme hydrolysis reaction chamber and performing enzymatic depolymerization of the PET using one or more enzymes, thereby generating a first reaction media.

[0013] Another aspect of the present disclosure provides a method of TPA precipitation through enriched hydrolysis reaction media. In some embodiments of the present disclosure, such a method may include providing a first enriched hydrolysis reaction media, where the enriched hydrolysis reaction media includes a first amount of ethylene glycol and a first amount of terephthalic acid. The method may also include initiating a media enrichment process by inputting the first enriched hydrolysis reaction media into at least one of a PET enzymatic hydrolysis reaction process, a chemical PET deconstruction process, a thermal PET deconstruction process, or a combination of such processes, thereby generating a second enriched reaction media by providing additional ethylene glycol and terephthalic acid to the first enriched reaction media. The method may also include repeating the media enrichment process until at least a portion of terephthalic acid (TPA) precipitates out of it associated enriched reaction media.

[0014] In some embodiments of the present disclosure, PET is provided to a PET enzymatic hydrolysis reaction process and / or other suitable PET deconstruction process. In some embodiments of the present disclosure, PET may be added prior to the initiation of the PET enzymatic hydrolysis reaction process. In some embodiments of the present disclosure, the PET may be added during the PET enzymatic hydrolysis reaction process.

[0015] In some embodiments of the present disclosure, a PET depolymerization process may include at least one of an enzymatic hydrolysis reaction process, a chemical PET deconstruction process, athermal PET deconstruction process, or a combination thereof. In some embodiments of the present disclosure, enzymes may be provided to the PET enzymatic hydrolysis reaction process. In some embodiments of the present disclosure, enzymes may be added prior to the initiation of the PET enzymatic hydrolysis reaction process. In some embodiments of the present disclosure, the enzymes may be added during the PET enzymatic hydrolysis reaction process.

[0016] A further aspect of the present disclosure provides a method of increasing efficiency of ethylene glycol recovery through enriched reaction media. Such a method may include providing a first enriched reaction media, where the enriched reaction media includes a first amount of ethylene glycol. The method may also include initiating a media enrichment process by inputting the first enriched reaction media into a PET depolymerization reaction process, thereby generating a second enriched reaction media by providing additional ethylene glycol to the first enriched reaction media. Additionally, the method may include repeating the media enrichment process one or more times, thereby generating an ethylene glycol-enriched hydrolysis reaction media. The method may also include providing the ethylene glycol- enriched reaction media to one or more distillation columns. Further, the method may include recovering an increased amount of ethylene glycol product from the distillation of the ethylene glycol-enriched reaction media as compared to the distillation of a similar amount of unenriched reaction media.

[0017] In some embodiments of the present disclosure, PET may be provided to the PET depolymerization reaction process. In some embodiments of the present disclosure, the PET may be added prior to the initiation of the PET depolymerization reaction process. In some embodiments of the present disclosure, the PET may be added during the PET depolymerization reaction process.

[0018] In some embodiments of the present disclosure, a PET depolymerization (i.e., deconstruction) reaction process may include an enzymatic hydrolysis reaction process. In some embodiments of the present disclosure, enzymes may be provided to the PET enzymatic hydrolysis reaction process. In some embodiments of the present disclosure, the enzymes may be added prior to the initiation of the PET enzymatic hydrolysis reaction process. In some embodiments of the present disclosure, the enzymes may be added during the PET enzymatic hydrolysis reaction process.

[0019] An additional aspect of the present disclosure provides a method of purifying TPA from a PET depolymerization product mixture. Such a method may include providing a hydrolytic solution comprising PET depolymerization products, where the PET depolymerization products include TPA. The method may also include adding an ammonium-base to the hydrolytic solution. Additionally, the method may include thermolysis, thereby generating recyclable ammonia and TPA salt precipitate.

[0020] A further aspect of the present disclosure includes a method of pre-treating PET substrates. Such a method may include extruding PET, thereby forming extruded strands of PET. The method may also include rapidly cooling the extruded PET strands. Further, a method may include chopping the extruded PET strands using a rotating knife unit.

[0021] Another aspect of the present disclosure is a method for retaining enzymes within a hydrolysis reactor system. Such a method may include providing a hydrolysis reactor system, wherein the hydrolysis reactor system includes a hydrolysis reactor and a rotating ceramic disc fdtration, where the hydrolysis reactor is communicatively coupled to the rotating ceramic disc fdtration. The method may also include generating a PET depolymerization hydrolytic solution at the enzymatic hydrolysis reactor system, where the PET depolymerization hydrolytic solution includes enzymes and PET depolymerization products. Additionally, the method may include directing the PET depolymerization hydrolytic solution to the rotating ceramic disc fdtration. Further, the method may include processing the PET depolymerization hydrolytic solution using the rotating ceramic disc fdtration, thereby generating a retentate, where the retentate includes at least a portion of the enzymes from the PET depolymerization hydrolytic solution. Additionally, the method may include recycling the retentate back to the hydrolysis reaction.

[0022] The present disclosure includes a further aspect of providing a method of isolating ethylene glycol via use of an acetal. Such a method may include providing an aqueous solution that includes ethylene glycol. The method may also include reacting the aqueous solution with an immiscible aldehyde over an acid catalyst, thereby generating acetal and ethylene glycol. The method may also include decanting the resulting mixture into unreacted aldehyde; a first layer that includes unreacted ethylene glycol; and an organic layer that includes acetal. Additionally, the method may include transferring the organic layer to a reactive distillation system. The method may also include isolating the ethylene glycol through use of one or more distillation columns within the reactive distillation system.

[0023] Without being bound to theory, there may be discussion herein of beliefs or understandings of underlying principles relating to the devices and methods disclosed herein. It is recognized that regardless of the ultimate correctness of any mechanistic explanation or hypothesis, an embodiment of the invention can nonetheless be operative and useful.

[0024] BRIEF DESCRIPTION OF DRAWINGS

[0025] Some embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than limiting.

[0026] Figure 1 illustrates a process flow diagram of a proposed PET enzymatic recycling process, according to some embodiments of the present disclosure.

[0027] Figure 2 illustrates a more detailed process flow diagram of the process of Figure 1, modified to include additional process developments to improve enzymatic PET recycling, according to some embodiments of the present disclosure.

[0028] Figure 3 illustrates data related to ethylene glycol recovery, according to some embodiments of the present disclosure.

[0029] Figure 4 illustrates the formation of a TPA salt utilizing ammonia, according to some embodiments of the present disclosure.

[0030] Figure 5 illustrates aspects related to the use of a rotating ceramic disc (RCD) to retain and recycle enzymes in a bioreactor, according to some embodiments of the present disclosure.

[0031] Figure 6 illustrates aspects of the current disclosure. Panel A illustrates a phase separation and reaction scheme, according to some embodiments of the present disclosure. Panels B and C illustrate plots showing the comparison of extraction efficiency at each EG loading, and demonstration of the “inflection point” if there is one.

[0032] Figure 7 illustrates a scheme for the preparation of TPA salts and their thermograms, corresponding to the thermal degradation of the salts to the starting amines and TPA, according to some embodiments of the present disclosure.

[0033] Figure 8 illustrates a method for recovering TPA utilizing a cation forming molecule (e.g., amines), according to some embodiments of the present disclosure. REFERENCE NUMERALS

[0034] 100 method

[0035] 103 TPA-rich stream

[0036] 105 salt-forming molecule

[0037] 110 forming

[0038] 112 salt (in solution)

[0039] 120 precipitating

[0040] 122 salt (solid in suspension)

[0041] 130 removing (solid)

[0042] 132 solid salt

[0043] 134 TPA-lean stream

[0044] 140 treating

[0045] 140A degrading (salt to form TPA and CFM)

[0046] MOB separating

[0047] 142 TPA stream

[0048] 144 CFM stream

[0049] DETAILED DESCRIPTION

[0050] The embodiments described herein should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein. References in the specification to “one embodiment”, “an embodiment”, “an example embodiment”, “some embodiments”, etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0051] The present disclosure relates to methods that can substantially improve the recovery of ethylene glycol and terephthalate released from the enzymatic hydrolysis of polyethylene terephthalate) (PET) and / or from other systems designed for the degradation / deconstruction / depolymerization of PET. In some embodiments of the present disclosure, such methods may include feeding additional substrate during and / or after an initial PET deconstruction reaction without recovery of ethylene glycol and / or without recovery of terephthalate salt and / or terephthalic acid. In some embodiments of the present disclosure, a process may include running a batch of PET enzymatic hydrolysis to completion and / or other PET deconstruction reaction, followed by the adding of additional substrate and / or additional enzyme, for the example of enzymatic hydrolysis. In some embodiments of the present disclosure, a process consistent with this approach may include adding new substrate and / or additional enzyme prior to running a batch of PET enzymatic hydrolysis to completion. In some embodiments of the present disclosure, this process can be repeated one or more times. In some embodiments of the present disclosure, this process can be repeated twice. In some embodiments of the present disclosure, this process can be repeated three times or more times. This process of enriching reaction media through repetition is referred to herein as solvent looping. In some embodiments of the present disclosure, solvent looping may achieve EG concentrations up to 50 g / L or up to 250 g / L. Additionally, processes of ethylene glycol recovery that are consistent with the approaches discussed herein can be applied to other processes as well. In some embodiments of the present disclosure, an ethylene glycol recovery process can be applied to chemical hydrolysis. In some embodiments of the present disclosure, an ethylene glycol recovery process can be applied to non-enzymatic PET depolymerization processes.

[0052] By enriching the reaction media with ethylene glycol and terephthalate, the concentration of EG in water, the energy demands of downstream separating processes may be proportionally reduced. In some embodiments of the present disclosure, increasing the EG concentration in a reaction media may cause at least a portion of the TPA to precipitate out as a solid. When coupled to reactive distillation, such a process may enable a substantial improvement in EG purity, with additional reductions in capital costs, operating costs, energy demands, and environmental impacts, including a reduction in GHG emissions.

[0053] As described herein, several additional complementary process developments to improve PET deconstruction and recycling are provided. In one aspect, a process of melt-extrusion followed by rapid quenching and chopping of the resultant PET fibers is provided as an energy-efficient, cost-effective amorphization step that enables comparable enzyme performance to benchmark amorphous substrates. In another aspect, enzyme retention in a hydrolysis reactor may be achieved utilizing rotating ceramic disc (RCD) filtration. In a further aspect, to eliminate salt generation arising from NaOH used for pH control and neutralization in an enzymatic hydrolysis reaction, NaOH may be at least partially replaced with at least one of NH3 and / or NH4OH, followed by downstream thermolysis of the resultant diammonium terephthalate salt to form NH3 for recycling to the hydrolysis reactor and TPA as a product for recovery and reuse in second generation polymers and / or resins. Further, it is shown herein that the reaction of butyraldehyde with concentrated EG enables reactive extraction of 2-propyl-l,3-dioxolane, which can be distilled to yield butyraldehyde and EG. Two or more of these various aspects may be combined in numerous ways to suit specific manufacturing plant design criteria, resulting in, among other things, reductions in process costs and lower environmental impacts across all life cycle inventory categories.

[0054] Approaches to Increase Efficiency of Product and Co-Product Recovery

[0055] The use of enzymatic hydrolysis to depolymerize PET into EG and TPA has some significant advantages over other PET depolymerization approaches.

[0056] To increase the efficiency of the recovery of PET deconstruction products via PET enzymatic hydrolysis processes and / or other PET deconstruction processes, methods are disclosed herein that are directed towards the generation of reaction media enriched in the PET deconstruction products. Among other things, methods are provided for enriching the amounts of EG and / or TPA present in reaction media. In some embodiments of the present disclosure, an enrichment process may occur one or more times after the completion of a first PET deconstruction step has been completed. In some embodiments of the present disclosure, an enrichment process may be integrated into a PET deconstruction process prior to the completion of the complete degradation of a first batch PET substrate. In some embodiments of the present disclosure, an enrichment process may itself be used as part of a TPA recovery process. In some embodiments of the present disclosure, a reaction media may be enriched by introducing additional PET substrate to a PET deconstruction process, either as part of a further step of PET deconstruction or as an additional part of a PET deconstruction process that has not yet been completed. In further embodiments, an enriched reaction media may be provided as an input to a PET deconstruction system so as to increase the amount (i.e., concentration) of EG and / or TPA contained within the PET deconstruction system.

[0057] In some embodiments of the present disclosure, one or more of EG and / or TPA may be present in an enriched reaction media. When additional PET substrate is added to this enriched media (via solvent looping), the depolymerization of PET may further increase the amount of EG and / or TPA present in the reaction media. By repeating solvent looping multiple times (e.g., two or more times), the EG and / or TPA concentrations may be incrementally increased. This increased amount of EG and / or TPA within an enriched reaction media may then provide efficiency benefits to the downstream recovery steps of EG and / or TPA from the enriched reaction media.

[0058] Regarding EG recovery aspects, it may be beneficial to provide EG-enriched media when feeding the media to a downstream distillation process designed to produce purified EG. Among other things, EG-enriched reaction media resulting from multiple solvent looping steps may reduce the environmental impact of a downstream distillation recovery process. While the individual impact of each distillation recovery process may be nearly the same when used to recover EG from a single PET enzymatic hydrolysis process versus multiple PET enzymatic hydrolysis processes, the net savings of being able to lessen the number of times a distillation recovery process is run may help to bring down the overall environmental impact of enzymatic hydrolysis processes as used to recycle PET. Again, these concepts are not restricted to the enzymatic degradation of PET and may be applicable to other methods of deconstructing PET; e.g., chemical, thermal, etc.

[0059] Regarding TPA recovery aspects, the use of EG- and / or TPA-enriched hydrolysis reaction media in multiple enzymatic hydrolysis processes may help to promote some aspects of TPA recovery without the need of moving to a further distillation step. In particular, at the point that a hydrolysis reaction media is enriched by running through two or more subsequent enzymatic hydrolysis reactions - with additional PET substrate being added prior to each enzymatic hydrolysis reaction - the conditions within the hydrolysis reaction media and the concentration of the TPA and / or the concentration of EG within the hydrolysis reaction media may cause a portion of the TPA to precipitate out of solution. In some embodiments of the present disclosure, depending upon factors such as the amount of additional PET substrate added to the reaction media, little or no TPA may precipitate as a solid. In some embodiments of the present disclosure, a portion of the TPA may precipitate as a salt. In some embodiments of the present disclosure, a relatively small amount of TPA may precipitate. In some embodiments of the present disclosure, a relatively large amount of TPA may precipitate. In some embodiments of the present disclosure, the majority of TPA may precipitate.

[0060] In some embodiments of the present disclosure, additional PET substrate may be added prior to each enzymatic hydrolysis reaction without adding further enzymatic material. In some embodiments of the present disclosure, additional PET substrate may be added prior to each enzymatic hydrolysis reaction with added enzymatic material. In some embodiments of the present disclosure, additional PET substrate may be added to each enzymatic hydrolysis reaction while adding further enzymatic materials in one or more of those enzymatic hydrolysis reactions.

[0061] While embodiments discussed above are centered around enriching hydrolysis reaction media associated with an enzymatic hydrolysis reaction, some further embodiments may be combined with other PET recycling processes that produce a solution having EG and TPA so as to increase the efficiency of downstream processing. In some embodiments of the present disclosure, a PET recycling process that is independent of enzymatic hydrolysis may result in depolymerized PET generating EG and TPA. These and other deconstruction products may be added to a water-based solution, creating an enriched EG media and / or TPA media that may then be added to an enzymatic hydrolysis process. As discussed above, in some embodiments of the present disclosure, the further enhancement of an EG- and / or TPA-enriched media may result in a portion of the TPA precipitating. This, in turn, may lessen the resulting burden on downstream recovery steps.

[0062] Figure 1 illustrates another detailed process flow diagram of a proposed PET enzymatic recycling process, in accordance with embodiments. In particular, the process flow diagram of the enzymatic PET recycling process as provided in Figure 1 illustrates individual subprocesses that are shown as labelled: feedstock pre-treatment of PET subdivided into flake preparation, and micronization; enzymatic hydrolysis to rEG and rTPA; monomer and coproduct recovery as subdivided into product clarification, TPA crystallization, and EG distillation; and repolymerization to rPET from rEG and rTPA (prefix “r” stands for recycled).

[0063] In the exemplary feedstock pre-treatment process as shown in Figure 1, PET is directed to an enzymatic hydrolysis process. A PET feed stream may include post-consumer PET products. These post-consumer PET products may include food containers, clothing, and / or other textile fabrics, gathered at a recycling center and / or through a recycling collection program in a community, among other examples. Of these collected products, some may not be suitable for recycling. In the example illustrated in Figure 1, the collected PET feedstock may be shredded into PET flakes and then sorted. In some embodiments of the present disclosure, sorting may be performed through various methods. In some embodiments of the present disclosure, sorting may be achieved via optical methods. In some embodiments of the present disclosure, sorting my include float-sink unit operations. While Figure 1 illustrates the production of a PET feed stream in the form of PET flakes, PET feed streams may take other shapes or forms. Referring again to Figure 1, a next step in a pre-treatment process may include washing and / or drying the PET flakes, resulting in cleaned PET flakes. For example, PET flakes may undergo an extrusion process, followed by a cryo-grinding process to form a PET powder with individual PET particles having length dimensions on the micron-scale. For the example of an enzymatic hydrolysis process, micronized PET powder may be fed to an enzymatic hydrolysis reaction chamber along with enzymes and a sodium hydroxide solution.

[0064] Referring again to Figure 1, a system may then proceed with a clarification step of the PET deconstruction reaction media, including filtering the media resulting in a solid stream, with the resulting filtered TPA-containing liquid stream directed to an activated carbon column. Further, a TPA crystallizer may recover a purified TPA stream and a second stream, which after additional processing steps, may result in a sodium sulfate by-product stream and an EG stream. Referring again to Figure 1, an important result of this exemplary system is the reuse of the recovered PET deconstruction products in a polymerization step to produce second generation polymers and / or resins.

[0065] In some embodiments of the present disclosure, referring again to Figure 1, for the example of enzymatic hydrolysis of PET, a hydrolase may be used as a biocatalyst. In embodiments, a PET hydrolase may be used as a biocatalyst. In embodiments, the enzymatic depolymerization of PET may be performed utilizing a 20% wt. charge of amorphized, cryomilled PET, contacted for up to 24 hours with a hydrolase at a reaction temperature up to 68 °C, in a reaction media containing 100 mM potassium phosphate maintained at a pH up to 8.0 (e.g., utilizing sodium hydroxide). In some embodiments of the present disclosure, ammonium hydroxide may be utilized to control pH.

[0066] Figure 2 illustrates additional details, to those illustrated in Figure 1. For example, process developments described herein may apply to the sub-processes shown in Figure 1. In an initial aspect, a pretreatment pelletization method for the amorphization of PET may be compared to the existing cryogrinding unit operation illustrated in Figure 1. Additionally, a fed-batch deconstruction scheme for ethylene glycol enrichment may be incorporated into the enzymatic hydrolysis sub-process (see Figure 1). Further, recycling and retention of PET hydrolase by nanofiltration using a RCD filter is also illustrated in Figure 1. Further, pH control using a recyclable base in place of sodium hydroxide may be used across both the enzymatic hydrolysis and monomer-co-product recovery sub-processes, with ammonium-hydroxide-controlled reactions conducted in bioreactors and TPA recovery obtained by thermal decomposition. Additionally, reactive concentration of EG to 2-propyl-l,3-dioxolane may be detailed as an alternative to distillation (see Figure 1).

[0067] Extrusion, quenching, and chopping for efficient PET amorphization.

[0068] Pre-treatment of PET feedstocks may be used to achieve the desired thermophysical characteristics that facilitate efficient enzymatic, chemical, and / or thermal depolymerization, especially a reduction in the crystallinity of the feedstock. In some embodiments of the present disclosure, a base case model of the enzymatic recycling plant, such as provided in Figure 1, may include steps for the melt-extrusion of PET flake followed by cryogrinding. As discussed herein, extrusion coupled to pelletization, where extruded PET strands undergo a rapid quench in a water bath prior to chopping by a rotating knife unit, can also achieve optimal amorphization and surface areas.

[0069] Cryo-milled PET powder, chopped strand PET, and virgin TPA were evaluated in a PET enzymatic recycling process, according to some embodiments of the present disclosure. For example, PET substrates derived by cryogrinding or pelletization were produced for a comparative depolymerization study. The pelletized substrate exhibited a crystallinity of 9.9 ± 0.2 %, and the cryomilled amorphous PET (amPET) powder a crystallinity of 10.2 %. The two substrates were enzymatically depolymerized in bioreactors at 10% wt. PET loading with pH control achieved using sodium hydroxide, at an enzyme loading of 3 mg / gPET. The fastest rate of depolymerization was achieved for the cryomilled amPET powder, which reached 100 % conversion after 10 hours of reaction. Comparatively, the extruded pellets achieved an initial rate of depolymerization of 26.7 % in 10 hours, with a 100 % conversion after ~50 hours. For the cryomilled amPET powder, mono-hydroxyethyl terephthalate (MHET) was released in a significant quantity during the first 10 hours, where it represented between 13.6 wt% and 56.6 wt% of the total product sum. In contrast, MHET represented between 2.3 wt% and 16.9 wt% of the total aromatic products released from the pelletized substrate, in the first 10 hours. By 48 hours, the aromatic products released from both substrates was 100 % TPA.

[0070] Ethylene glycol solvent-looping coupled to disodium terephthalate recovery.

[0071] EG recovery by distillation accounts for 99% of steam consumption and greatly contributes to the GHG emissions of a PET enzymatic recycling facility. Therefore, the ability to concentrate EG prior to product recovery may reduce both process costs and GHG emissions, as well as utilize the relationship of decreasing solubility of terephthalate salts in increasing ethylene glycol concentrations. A series of fed-batch hydrolysis reactions run to conversion with recycling of the terephthalate salt-water-ethylene glycol liquors was modelled to enrich EG and to minimize process water use. The activity of enzyme (LCCICCG) under EG concentrations determined to precipitate disodium TPA (dsTPA) salts as modelled in multi-pass PET deconstruction reactions was first determined in small-scale reactions (see Panel A of Figure 3). Small-scale depolymerization reactions were run with amorphous PET films, where the enzyme was incubated in the presence of increasing ethylene glycol concentrations in 100 mM sodium phosphate pH 8 and the total aromatic product release over 24 hours at 65 °C quantified by ultra-performance liquid chromatography (UPLC) (see Panel A of Figure 3). To evaluate tolerance over time, the hydrolase enzyme was pre-incubated under the same reaction conditions for 4 days at 65 °C, prior to initiation of the 24-hour hydrolysis reactions (see Panel B of Figure 3).

[0072] Panels A-F of Figures 3 illustrate data related to ethylene glycol recovery, in accordance with embodiments. In some embodiments of the present disclosure, enzyme recovery and reuse may be greater than 3. Reaction conditions are described as for the base case model. Panel C of Figure 3 provides multiple enzymatic deconstruction recycles with PETase LCC-ICCGin reactions pH-controlled by sodium hydroxide. The percent conversion of PET displayed as calculated by NaOH consumption considering an exclusive production of TPA and MEG (assuming 2 mols of NaOH titrate 1 mol of the diacid TPA). Multiple enzymatic deconstruction recycles in reactions pH-controlled by ammonium hydroxide for n=2 reactors are shown in blue. The repeating Mwunit of PET, 192.17 gmol"1was used to calculate the maximum theoretical yield in mols of TPA per addition of PET. Panel D of Figure 3 provides a graph of (NH4+)I .9TPA solubility in the presence of increasing concentrations of ethylene glycol in EG- water mixtures at 65 °C. Panel E of Figure 3 provides TGA data for the chemically synthesized ammonium terephthalate salt illustrating the thermal cracking event at ca. 190 °C. Panel F of Figure 3 provides TGA data for the ammonium terephthalate salts recovered from the multipass 5-recycles. Figure 4 provides a summary scheme illustrating the reaction of TPA with ammonium hydroxide to yield diammonium TPA (daTPA) salt followed by the subsequent regeneration of ammonium hydroxide via thermolysis.

[0073] Based on the EG tolerance of LCCICCG, multi -recycle enzymatic deconstructions were carried out using sodium hydroxide for pH-control in bioreactors at reaction temperatures of about 65 °C. Five consecutive depolymerization reactions maintained at pH 8 by sodium hydroxide addition were run with additional PET substrate loading (15 % wt. loading of 0.25 L) with enzyme loading (3 mg / g) added to the reactors after each 24 hours in duplicate reactors. The base consumption profiles confirmed maintained depolymerization conversion extents by LCCICCGin the sodium hydroxide case, with 95% depolymerization after each 24 hours measured across all reactions (see Panel C of Figure 3). During the second solution recycle, the dsTPA salts reached saturating concentrations and precipitated out. While the residual dry weight of unreacted PET is a typical metric to calculate extents of enzymatic conversion, in the case where the solids formed are precipitated salts this metric does not apply. The precipitated dsTPA solids produced by the end of recycle 4 were filtered off from the reaction liquor, dried in a vacuum chamber, weighed, and both the precipitated and solution dsTPA and ethylene glycol quantified against a commercial standard using 1-D NMR (see Table 1). A final yield of 93.47 ± 2.41 g of daTPA was calculated based on a purity of 88.81 ± 0.8 %. Residual solids (unreacted PET) accounted for 7.24 ± 0.78 % of the total solids recovered. The solution and solid daTPA and ethylene glycol yields are summarized in Table 1, from which an overall average yield of 87.8% was calculated by NMR.

[0074] Table 1: Yield quantification by 1-D NMR analysis of Na2TPA solids recovered by filtration and the solution reaction liquors from 3-recycles (n=2 reactors), and 5-recycles (n=2 reactors).

[0075] Ethylene glycol solvent-looping coupled to diammonium terephthalate recovery.

[0076] Another major environmental contributor is the sodium hydroxide consumption associated with the pH control of enzymatic PET reactions. Eliminating reaction pH control stands to reduce the environmental impacts to levels statistically equivalent to virgin TPA and PET production. The use of a recoverable base, such as ammonia, may eliminate or reduce the GHG emissions associated with the base control of PETase-mediated reactions, while enabling improved rTPA recovery. A thermal decomposition of diammonium terephthalate product coupled to ammonia recapture is a viable reaction route to achieve an effective net zero base consumption. Replacing the previously modelled sulfuric acid precipitation rTPA recovery route, in part or completely, with thermal decomposition may also reduce the associated reduced salt waste process outputs. Additionally, the use of ammonium hydroxide and / or ammonia as a base, when coupled to downstream thermal cracking to reduce and / or eliminate salt waste, may also be used for other non-enzymatic PET depolymerization approaches. For example, this approach may be applicable for downstream separation of TP A from other hydrolytic products. In some embodiment of the present disclosure, this approach may be used to separate out TPA from a neutral hydraulic process without the use of enzymes. In some embodiments of the present disclosure, this approach may be used to separate TPA from an alkaline hydraulic process without the use of enzymes. In some embodiments of the present disclosure, this approach may be used to separate TPA from an acidic hydraulic process without the use of enzymes. Additionally, since the solubility profile in EG / water mixtures for ammonium terephthalate is similar to sodium salt, EG enrichment by solvent recycling may provide an advantage for this chemistry as well, such as increasing precipitation of the TPA anion.

[0077] Subsequently, the concentration of daTPA as a function of ethylene glycol concentration was determined via quantitative1H NMR at the operational temperature of LCCICCGin a bioreactor, 65 °C (see Table 2, Panel D of Figure 3). Increasing the concentration of EG decreased the solubility of (NH4)I.9TPA. However, as the concentration of EG reached -500 g / kg, the solubility increased slightly to a plateau, confirming a relationship of decreasing solubility at bioreactor-relevant concentrations of EG. Notably, the solubility of the ammonium salt was lower than that of the sodium salt, with potential to ease its isolation from the enzymatic deconstruction reaction as a precipitate.

[0078] Table 2: (NH4+)I.9TPA solubility in the presence of increasing concentrations of ethylene glycol in EG- water mixtures at 65 °C.

[0079] Having established the decreasing solubility of the (NH ) TPA salt with increasing EG concentration, multi-recycle enzymatic deconstructions were carried out using ammonium hydroxide for pH-control in bioreactors at 65 °C, with 4 reuses of the reaction liquor at pH 8.4, with 50 mM daTPA as a buffer (see Panel C of Figure 3). Five consecutive depolymerization runs maintained at pH 8.4 by ammonium hydroxide addition produced the final reaction liquors, with additional substrate (10 % wt. loading cryomilled PET powder of 0.25 L) and enzyme loading (3 mg / g) added to the reactors after each 24 hours (see Panel C of Figure 3). Experiments and analyses were performed in duplicate reactors, where the error bars in the figures are the range of the two duplicates. A starting solution of daTPA buffered with ammonium hydroxide was selected to eliminate contaminating ions (e.g., chloride, phosphate, sodium) in the downstream separation recovery of TPA and to increase the concentration of the conjugate acid / base pool for increased buffering capacity compared to water. The elimination, or at least minimization, of NaCl and phosphate also worked to enable efficient downstream cyclization of ethylene glycol by cation exchange (CEX) to form the cyclic acetal, where residual cations were able to saturate the catalyst resin and reduce efficiency.

[0080] The depolymerization conversion efficiency by LCCICCG, as measured by ammonium hydroxide consumption, was maintained across the subsequent recycled EG-daTPA reaction profiles (see Panel C of Figure 3). During the second solution recycle, the daTPA salts reached saturating concentrations and precipitated out. The precipitated daTPA solids produced by the end of recycle 4 were filtered off from the reaction liquor, dried in a vacuum chamber, weighed, and quantified against a commercial Na2TPA salt standard using 1-D NMR (see Table 3). A final yield of 54.39 ± 3.73 g of daTPA was calculated based on a purity of 93.43 ± 2.16 %. Residual solids accounted for 6.46 ± 4.36% of the total solids recovered (see Table 3). Thermogravimetric analysis (TGA) of the solids confirmed the recovery of an ammonium salt with 1.7 equivalents of NFh incorporated (see Panel F of Figure 3). The solution and solid daTPA and ethylene glycol yields are summarized in Table 3, where an overall average yield of 91.08 % was calculated by NMR. The solution samples comprised 10.64 ± 0.21 % wt. daTPA, comparatively lower than the 12 %wt. yields determined for solution dsTPA in the sodium -hydroxide multi-recycle reactions (see Table 1).

[0081] Table 3: Yield quantification by 1-D NMR analysis of daTPA solids recovered by filtration and the solution reaction liquors from 5 -recycles (n=2 reactors).

[0082] Thermal decomposition of diammonium terephthalate for recovery of terephthalic acid. A thermal decomposition of the diammonium terephthalate salt product to terephthalic acid enables the recapture and reuse of the ammonia for neutralising subsequent deconstruction reactions. This development can change the overall stoichiometry for base addition, with an efficient hypothetical reactor design enabling essentially net-zero base usage. To identify optimal parameters for the modelled daTPA cracking step, TGA thermograms were collected on the solids samples from the bioreactor as well as the synthetic daTPA. It was found that 190 °C provided sufficiently rapid ammonia evolution, while being well below the ca. 250 °C onset of TPA sublimation. This data also confirmed the identity of the bioreactor precipitate, with the salt containing 1.7 equivalents of ammonia, rather than the 1.9 equivalents seen in the synthetic sample (see Panels E and F of Figure 3). This lower ammonia incorporation did not appear to have an impact on the rate of thermolysis.

[0083] Enzyme retention and recycling by rotating ceramic disc technology.

[0084] To demonstrate a membrane process to recycle mNeonGreen (mNG), a constitutively fluorescent green / yellow reporter protein (My, ~ 26.6 kDa), or LCCICCG(My, ~ 28.7kDa), ultrafiltration experiments were carried out using a bench-scale batch tangential flow system where the retentate was recycled back to the feed solution. A ceramic disc with a nominal molecular weight cut-off (MWCO) of 1 nm or 5 nm was used. Reaction mixtures of EG and dsTPA in 100 mM sodium phosphate pH 8.0 were prepared to simulate a 50% conversion of 15% wt. loading in IL. mNG or LCCICCGwere added at 0.2 mg / g of PET. Filtration was carried out at 55 °C. The permeate was collected until a 50% volume reduction of the initial solution was achieved. Feed, final retentate, and final permeate sample at 50% volume reduction were analyzed by downstream enzymatic activity assays with kinetic rate measurements, UPLC quantification, or RFU measurements. For the analysis of final retentate and final permeate a constant UF / NF permeance during operation was assumed.

[0085] Panels A-F of Figure 5 illustrate aspects related to the use of a RCD filter to retain and recycle enzyme in a bioreactor, according to some embodiments of the present disclosure. Panel A of Figure 5 illustrates a standard curve of the average fluorescence measured as relative fluorescence units of purified monomeric NeonGreen protein (mNG) diluted to concentrations between 0-0.75 mg / mL. All dilutions were made in a 100 mM sodium phosphate pH 8 buffer with product loadings of EG and dsTPA equivalent to a 50% conversion of a 15 % wt. loading of PET in 1 L. Inset is the linear part of the standard curve between 0-0. 1 mg / mL. Panel B of Figure 5 illustrates relative fluorescence units of mNG measured in the permeate, feed (before RCD), and resulting retentate solutions. Panel C of Figure 5 illustrates a pH profile of mNeonGreen after 2-hour incubation of mNG at each pH interval at 55 °C. Panel D of Figure 5 illustrates a temperature profile of mNeonGreen after 2-hour incubation at each temperature. All fluorescence measurements were recorded in triplicate. Panel E of Figure 5 illustrates a Michaelis-Menten curve (y = I naxxI ( m +x)) fitted to the rate of ICCG in the retentate with increasing concentrations of 4-nitrophenyl acetate. The axes are displayed on a log scale. Panel F of Figure 5 illustrates relative enzymatic kinetic activity of LCCICCGin the retentate and permeate solutions determined at 25 °C in 100 mM sodium phosphate pH 8.0 buffer using absorbance change with 2-carbon chain substrate, 4-Nitrophenyl acetate.

[0086] Reactive concentration of ethylene glycol via acetal formation and distillation.

[0087] As an alternative ethylene glycol recovery route, a reactive concentration step was modelled into the downstream recovery processes in place of intensive distillation (see Panels A-C of Figure 6). By first reacting the ethylene glycol with an aldehyde over an acid catalyst, EG can react to form an acetal, trapping one equivalent of ethylene glycol in a now organic-soluble form. Acetals are formed by the reaction of aldehydes and / or ketones with alcohols, which examples including diethoxy ethane, polyoxymethylene, dioxolane, and metaldehyde. In some embodiments of the present disclosure, an aldehyde reacted with EG may be immiscible. In some embodiments of the present disclosure, the aldehyde may be partially miscible. In some embodiments of the present disclosure, the aldehyde may be miscible.

[0088] In some embodiments of the present disclosure, one or more alternative aldehydes may be used in this approach. For example, alternative aldehydes may include aldehydes that are capable of forming an acetal in the reaction conditions present in the enzymatic hydrolysis reactor, and that are capable of being distilled for ethylene glycol recovery. In some embodiments of the present disclosure, the boiling point of the resulting acetal may be lower than that of water (in this case), as well as ethylene glycol, so that there is an energetic benefit inherent in the conversion to the acetal. In some embodiments of the present disclosure, an aldehyde may have five or fewer carbons including, for example, formaldehyde and / or acetaldehyde. In some embodiments of the present disclosure, the aldehyde and acetal’s solubility may be low enough in the depolymerization solvent so that phase separation is possible. In the processes consistent with those described herein, an aldehyde may include at least one of n-and / or isobutonal.

[0089] In non-enzymatic processes, the same or other aldehydes may be used. In some embodiments of the present disclosure, for an approach directed towards an ethylene glycol post-processing step in methanolysis, the aldehyde may be pentanal. In additional or alternative embodiments related to methanolysis, the aldehyde may be isovaleraldehyde.

[0090] In some embodiments of the present disclosure, a choice of aldehyde may be based on a boiling point of a solvent. In some embodiments of the present disclosure, a solvent (e.g., water, alcohols, etc.) that boils higher than 100 °C (e.g., hydrolysis, long-chain alcoholysis) may use a short chain aldehyde to enable distillation at temperatures below 100 °C. In this case, immiscibility may be a limitation. In some embodiments of the present disclosure, a solvent that boils lower than 100 °C (e.g., methanolysis) may have a process for EG purification rather than isolation. This may be due to the solvent that is used for degradation may be evaporated first. In this case, an acetal that boils lower than the EG may be used.

[0091] Residual unreacted aldehyde will separate into an immiscible phase, and the two resultant layers may be decanted resulting in an aqueous layer with some percentage of EG extracted and an organic layer than can be transferred to a reactive distillation step, where the aldehyde is liberated and separated from ethylene glycol such that the aldehyde may be recycled. This is advantageous because the aldehyde butyraldehyde has a boiling point at 1 atmosphere of only 74.8 °C, as compared to 197 °C for ethylene glycol, so the overall energy input can be significantly lowered.

[0092] In some embodiments of the present disclosure, reactive distillation to recover ethylene glycol through acetal chemistry may be used in non-enzymatic PET hydrolysis. In some embodiments of the present disclosure, this approach may be used in acidic hydrolysis of PET. In some embodiments of the present disclosure, this approach may be used in alkaline hydrolysis of PET after neutralization. In some embodiments of the present disclosure, this approach may be used in neutral hydrolysis of PET. In some embodiments of the present disclosure, this approach may be beneficial for use when there are low concentrations of EG present after PET degradation reactions. When EG concentration is very low the energy cost to distill the water and recover EG may be prohibitive. In cases where recovery of EG isn’t economically viable by simple distillation, use of a reactive extraction may have a significant benefit, such as a cost benefit.

[0093] Rather than determine detailed thermodynamic values, a variety of screening experiments were performed based on anticipated conditions from upstream PET degradation. After the acetal reaction reaches equilibrium, a mixture of acetal and unreacted aldehyde may be present in the organic fraction, and a mixture of soluble aldehyde, the aldehyde’s hydrate, the acetal, and residual ethylene glycol may be present in the aqueous fraction (see Panels A-C of Figure 6). Conveniently, the two fractions can be sampled separately, and the concentrations of each of these species determined via quantitative1H NMR. From this concentration data, it is possible to determine the amount of ethylene glycol that has been removed from the aqueous solution by partitioning. In some embodiments of the present disclosure, that amount may be subsequently recoverable via hydrolysis and subsequent distillation.

[0094] A simple solution of 7 wt% EG in deionized water was evaluated with a two-molar equivalence of butanal (i.e., butaldehyde, butanaldehyde, and butalyde) (relative to the starting concentration of EG) used in each of three reactive concentration steps. In some embodiments of the present disclosure, the butanal equivalence selection may be based on the phase separation behaviour at low loadings of EG on small scale . In some embodiments of the present disclosure, some excess may be included to facilitate sampling of both layers. For these bench scale experiments, a fresh catalyst bed (20 wt% relative to starting solution volume) was used each time, to model the ideal behaviour of an industrial multi-pass setup more accurately. It was found that, by the third reactive concentration pass, 85% of the ethylene glycol had been extracted. To evaluate the impact of potential contaminants from the PETase degradation, the same protocol was applied to the two daTPA product solutions after they had first been acidified with H2SO4 (see Figure 6). No significant deviation was found between the relatively similar concentrations of contaminant free EG / H2O and the bioreactor products (see Figure 6).

[0095] To examine the reactive concentration’s relationship to the potential best-case scenario for solvent looping, multiple water / EG model solutions were subjected to the same protocol for reactive concentrations. As with the previous studies, the amount of butanal used in each pass was 2 molar equivalents based on the measured concentrations of the solutions, so for higher EG loadings the volume of aldehyde was therefore significantly higher.

[0096] Enzyme production and purification.

[0097] A DNA clonal gene of the ICCG variant of leaf-branch compost cutinase (LCC, UniProtKB G9BY57) was synthesized in a pET-21b(+) expression vector (Twist Bioscience) and transformed into OverExpress Escherichia coli C41 (DE3) Chemically Competent Cells (Biosearch Technologies). Transformed cells were plated on lysogeny broth (LB) agar plates containing 100 pg / mL ampicillin and incubated at 37 °C overnight. A starter culture was grown from a single transformation colony in LB containing ampicillin (100 pg / mL) at 37 °C, 250 rpm overnight. The cultures were grown in 2 x YT media under ampicillin selection by using a 100-fold dilution of the overnight starter culture as the inoculum, induced at an optical density (ODeoo) of 0.6-0.8 with 1 mM isopropyl p-D-l -thiogalactopyranoside (IPTG) and grown for 20 h at 18 °C, 150 rpm. The cell biomass was harvested by centrifugation and frozen at -80 °C before resuspension. The biomass was resuspended in lysis buffer (20 mM Tris pH 8, 10 mM imidazole, 300 mM NaCl, 1 mg / mL lysozyme, 50 pg / mL DNAase) and subjected to sonication (QSonica Q700). The resulting cell lysate was cleared by centrifugation at 40,000 x g for 40 min at 4 °C and passed through a 0.45 pm filter. Immobilized metal-affinity chromatography was performed using a 25 mL HisTrap HP column (Cytiva) linked to an AKTA Pure chromatography system pre-equilibrated with the lysis buffer. An elution gradient of 2 column volumes with an elution buffer of 20 mM Tris pH 8, 300 mM NaCl, 500 mM imidazole was applied to elute the protein. The fractions containing the eluted protein were pooled, concentrated, and exchanged into 20 mM Tris pH 8, 300 mM NaCl by dialysis overnight.

[0098] Amorphous PET powder production and analysis.

[0099] A micronized powder was produced from a 1.5 mm-thick, amorphous PET (amPET) film sheet supplied by Goodfellow (product number ES30-SH-000115). The 600 x 600 mm sheet was manually cut into 100 x 50 mm rectangles which were immersed in liquid nitrogen and cryocut at 2400 rpm in a SM300 cutting mill (Relsch) equipped with a stainless-steel V-rotor, a bottom sieve with 4 mm square holes, and a cyclone trap for product collection. Subsequently, this cryo-cut product was cooled in liquid nitrogen and subjected to further size reduction by cryo-milling at 18,000 rpm in a ZM200 centrifugal mill (Relsch) equipped with a stainless- steel 12-teeth push-fit rotor, a ring sieve with 0.25 mm trapezoidal holes, and a cyclone trap. After drying under vacuum for 1 hour at 60°C, the particle size and shape distributions in a sample of the amPET powder was assessed by dynamic image analysis using a CAMSIZER X2 (Microtrac MRB) with X-Fall module.

[0100] Twin-screw extruded pellet production and analysis.

[0101] A 15 mm diameter Technovel twin screw extruder (Technovel Corp., Japan) was used to extrude the RPET pellets. As-received RPET bottle flakes were fed at 9 g / min feed rate into an L / D 60: 1 twin screw extruder barrel rotating at 200 RPM. The heating profile was set to 245 °C at the feed zone and increased to 270 °C at the die head. The screw was programmed using a profile detailed previously.29Extrudate was cooled in a chilled (~ 4 °C) water bath and the chopped strands (pellets) produced by pulling the extrudate through the water bath using a pelletizer which chopped the extrudate into cylindrical pellets.

[0102] Differential scanning calorimetry of PET substrates. The crystallinity of the pelletized and cryomilled PET substrates was determined in triplicate by differential scanning calorimetry (DSC) using a Q2000 DSC (TA Instruments) on 9-10 mg of each sample placed in hermetically sealed aluminium pans. The samples were analysed from 0 to 300 °C at a rate of 10 °C min-1. The glass-transition temperature (Tg), heat of melting ( Hm), and heat of cold crystallization (AHCC) were determined with TA TRIOS. Percent crystallinity was calculated using the following equation, where AHm° is the reference heat of melting for PET = 140.1 J g-1.

[0103] % crystallinity = [ Hm- H<x\l Hm° x 100%

[0104] Chemical synthesis of diammonium terephthalate.

[0105] To a 250 mb round bottom flask equipped with a magnetic stir bar, 10.008 g of terephthalic acid (60.24 mmol, 1.0 eq) was suspended in 125 mb of water. 28-30 wt% ammonium hydroxide solution (25.83 g, 206 mmol NH3, 3.42 eq) was added and the mixture was stirred until all solid was dissolved, about 30 minutes. The water and excess ammonia were removed with a rotary evaporator then 100 mb of benzene added to the residue. The benzene was then removed with a rotary evaporator to azeotrope off residual water, and this process was repeat two additional times to afford diammonium terephthalate in 97% yield (11.698 g, 58.43 mmol) [based on the MW of pure diammonium TP A] . The identity of the salt was confirmed by TGA, where it was found that 1.9 equivalents of ammonia were incorporated into the crystalline solid based on the observed mass loss between 150 and 250 °C.

[0106] TGA validation of diammonium terephthalate.

[0107] All thermogravimetric analysis was performed on a TA Instruments Discovery 5500 TGA with a 10 °C / min ramp rate from ambient (~25 °C) to 600 °C under a 25 ml / min N2 flow. As the isolated ammonium terephthalate product represents a snapshot of the equilibrium conditions for the double deprotonation by the relatively weak base NH4OH, thermogravimetric analysis (TGA) was used to calculate the degree of deprotonation. Por each equivalent of carboxylate generated, one equivalent of ammonia is released upon heating. The total equivalents of incorporated ammonia can therefore be calculated from the weight loss during this event, where a 17.01% decrease corresponds to full conversion to the diammonium salt. It was found that, regardless of the approach used to isolate the salt, approximately 1.9 equivalents of ammonia are incorporated with 0.1 equivalents of carboxylic acid remaining, in the synthetic samples. Identical experiments on the bioreactor solids confirmed the presence of the daTPA salt as a precipitate with 1.7 eq. of incorporated ammonia. Solubility determination of daTPA in various EG / H2O solutions.

[0108] To individual 4 mL vials, approximately 300 mg of the synthetic ATPA was suspended in water or a solution of ethylene glycol in water. The vial was placed on a hotplate in an aluminium heating block held at the desired temperature, or an ice bath with a thermometer, and the mixture was stirred vigorously for 30 minutes to ensure full saturation of ATPA. The stirring was stopped, and the solids allowed to settle for a further 30 minutes at which point three separate 50 pL aliquots were taken via positive displacement pipette, with special care to move quickly and avoid pipetting any solid. In separate vials, these samples were diluted to 0.5 mL using a solution of D2O containing NaOAc as an internal standard. NMR spectra were collected with 16 scans and a relaxation delay of 20 seconds to ensure accurate quantification and the zg30 pulse program. Triplicate samples were prepared from each saturated solution, and the reported error is the standard deviation between those samples.

[0109] Bioreactor multi-reuse deconstruction ammonium hydroxide-controlled reactions.

[0110] Bioreactor hydrolysis reactions were initiated at 0.25 L scale in duplicate IL glass bioreactors (Applikon Biotechnology), which included two Rushton impellers in the stirrer shaft below the 0.2 L line. The substrate used was cryomilled amorphous PET powder of 10.2 % crystallinity. For the first reaction, 25 g of substrate was added to 50 mM daTPA buffer pH 8.4 assay buffer at a final volume of 0.25 L and equilibrated to 65 °C with stirring at 400 rpm. The reactions were initiated by the addition of 15 mL of 5 mg / mL LCCICCGfor a final enzyme loading of 3 mg / g PET and proceeded for 24 h maintained at pH 8.4 with 4 M NH3OH addition using a peristaltic pump controlled by an in-control module (Applikon Biotechnology). For each subsequent recycle reaction, every 24 h, a fresh addition of 25 g substrate and 15 mL LCCICCGwas added to the reactors. Sample volumes of 0.5 mL were removed at 0, 1, 5 and 24 hr timepoints of each respective batch reaction, quenched with methanol and stored. At the end of the 5 reactions, the precipitated solids were filtered off from the reaction liquors, dried in a vacuum chamber at 40 °C for 5 days, and weighed prior to UPLC quantification, TGA characterization and NMR purity analysis.

[0111] Preparation of 50 m daTPA buffer: As ammonium deprotonation has a high ArH° (standard molar enthalpy of deprotonation) value of 51.95kJ / mol, the pH of the ammonia / ammonium buffer system is highly temperature sensitive. A titration curve was run at room temperature to determine the buffering capacity between the carboxylic acid / base by 0.1-0.25 mL aliquot additions of ammonium hydroxide to a solution of 50mM daTPA dissolved water until a pH of 9 was achieved. To prepare the daTPA buffer, 4.96 g of daTPA was dissolved in a solution of 500 mL of water, heated to 65 °C, adjusted to pH 8.4 using 4M ammonium hydroxide solution and cooled to room temperature. At room temperature, the pH of buffer was re-recorded as 9.35.

[0112] NMR analysis of disodium terephthalate and ethylene glycol yields.

[0113] Samples were weighed out into tared 1-dram vials and to each sample was added 600 pL of D2O. The solutions were filtered through a cotton plug packed into a disposable, 9” Fisher pipette, transferred into a Norell 7”, 5 mm, medium walled NMR tube and sealed for analysis. All NMR experiments were performed on a Bruker Avance III 400 MHz spectrometer fitted with a 5 mm Prodigy BBO LN2 cryoprobe. Inversion recovery experiments were conducted to measure Ti relaxation rates for each signal and the acquired values were used to determine quantitative proton NMR relaxation delays. Relaxation delay (dl) for quantitative 'H acquisitions were set to at least 7 times the longest Ti of interest. Due to the use of a disodium terephthalate external reference, experiment parameters were duplicated with the ‘wrpa’ command to ensure comparable absolute integrals between samples after the maximum receiver gain (rg) needed across all samples was determined. The longest Ti relaxation time corresponded to water, which crossed the null between 7 and 10 seconds while both glycol and dsTPA displayed relaxation to the null between 3 and 5 seconds. To ensure quantitative signal recovery between pulses, the relaxation delay was set to 120 s for 8 scans. To avoid ADC overflow errors, the receiver gain value was set to 10. Otherwise, default parameters were used from the Bruker ‘zg’ pulse program.

[0114] TPA / MHET / BHET UPLC quantification

[0115] Analysis of aromatic products TPA, MHET and bis-2-hydroxyethyl terephthalate (BHET) was performed by ultra-high performance liquid chromatography (UHPLC) as previously described. In brief, samples were injected onto a Zorbax Eclipse Plus C18 Rapid Resolution HD column and separation was achieved using a mobile phase gradient of 20 mM phosphoric acid and methanol. Diode array detection (DAD) was utilized for quantitation for the analytes of interest using a wavelength of 240 nm.

[0116] Reactive concentration on representative EG samples.

[0117] The molar concentration of ethylene glycol in the 4 solutions (7, 13, 25, and 50 wt% EG in water) was determined via 'H NMR in D2O (NaOAc internal standard). This value was used to select the precise amount of butanal to be used for each pass. A volume of each solution was measured and added to a 100 mL round bottom flask equipped with a magnetic stir bar, and the flask transferred to an aluminium bead bath at 35 °C. The amount of solution was varied for each EG concentration so that the total volume (solution plus butanal) was approximately 25 mL. Amberlyst-36 (20 wt% relative to starting volume of EG solution) was then added along with 2 molar equivalents butanal. This biphasic mixture was stirred vigorously for 1 hour to ensure equilibration. The contents were then poured through a small glass wool plug and into a separatory funnel, where the aqueous layer was decanted off and triplicate 'H NMR samples were prepared using 10 pL of sample and 490 pL of D2O (with NaOAc i s ). The organic layer was pipetted to a separate vial, and triplicate 'H NMR samples were prepared (DMSO-d6, trimethoxybenzene internal standard). The aqueous layer was transferred back to the rinsed and dried round bottom flask with stir bar, and the exact same amounts of butanal and Amberlyst-36 were added. The mixture was again stirred for 1 hour, and the separation and quantification procedure was repeated. This entire process was repeated one additional time, for a total of three reactive concentration passes. All 18 NMR samples were evaluated using a 20 second relaxation delay, 16 scans, and the zg30 pulse program for minimal acquisition time.

[0118] Ethylene glycol extraction efficiency (EEeg) was calculated using equation 1.

[0119] ( [EG]aa+[Acetal]„nx EEeg=100- (100*aq[EG]oaq) (1)

[0120] Reactive concentration on bioreactor samples.

[0121] A 40 mL sample of each of the multi -reuse bioreactor runs was neutralized with 1.6 mL concentrated H2SO4, which lowered the pH to ~2 and precipitated all dissolved daTPA as TPA. This slurry was filtered, and the masses of the recovered TPA were 5.25 and 5.60 g for Bl and B2 respectively. The mass of these undried recovered solids is in reasonable accord with previously determined solubility values. To determine the appropriate butanal concentration, the EG concentration was determined as described above. Reactive concentration was performed via an identical procedure to the pure EG / Water experiments using 25 mL of the filtrate and the appropriate amounts of butanal and Amberlyst-36.

[0122] Alternative bases.

[0123] Other bases, in addition to or replacing ammonium hydroxide may be used to react with terephthalic acid (TPA) to form TPA salts, which may be subsequently precipitated from a mixture for the eventual recovery of the TPA. In some embodiments of the present disclosure, at least one of alkylamine and / or a dialkylamine may be added to a solution (e .g . , a fermentation broth, fermentation media, a hydrolytic solution, etc.) to form an amine salt of TPA. Examples of amines that may be used to form TPA salts include amines having at least one alkyl group having between 1 and 10 carbon atoms. Examples of alkyl groups bonded to an amine include methyl, ethyl, propyl, butyl, pentyl, and hexyl groups. Among other amines, both n-butylamine and diethylamine have been successfully tested for this purpose. Figure 7 illustrates a scheme for the preparation of TPA salts and their corresponding thermograms, corresponding to the thermal degradation of the salts to the starting amines and TPA. Other amines that may be utilized similarly in such a process include benzylamine, cyclic aliphatic amines, ethanolamine, and morpholine. Morpholine and ethanolamine have been tested and can result in charring of the TPA during thermolysis. However, both morpholine and ethanolamine did work for both precipitation in acetone and thermal recovery of amine.

[0124] The thermogravimetric analysis (see Figure 7) reveals the ability of n-butylamine and diethylamine to thermolyze to TPA and their starting amine at low temperatures. Crucially, this process occurs at a low onset temperature (<130 °C). This lowers, compared to salts that thermally decompose at higher temperatures, the energy input required for the cracking process and increases the window between cracking and sublimation. The salts of triethylamine and pyrrolidine have also been synthesized, but do not thermolyze below the sublimation point. Additional key parameters for an ideal amine in this process are water miscibility and boiling point. An immiscible amine will not effectively operate in a bioreactor, and if it boils significantly above water (>150 °C) it may be difficult or energetically costly to isolate the amine.

[0125] Referring again to Figure 7, next the water solubility of the TYA salts was evaluated to determine their viability for enzymatic depolymerization of PET. Among other things, this process utilizes the decreasing solubility of the TPA salt in increasing concentrations of ethylene glycol (EG). The solid PET is first hydrolyzed to a soluble TPA salt and, once a certain salt concentration is reached, the solid TPA salt precipitate is isolated and processed. Therefore, for TPA salt to be suitable for this process, it can be advantageous for the TPA salt to be sparingly soluble in the water / EG mixture resulting from depolymerization. Both butylammonium TPA (BATPA) and diethylammonium TPA (DEATPA) were found to have remarkably high solubility in water and 50 wt% EG. BATPA is soluble up to 1.9 kg / L in water and 1.3 kg / L in 50 wt% EG, and DEATPA is soluble up to 2.5 kg / L in water and 2.1 kg / L in 50 wt% EG.

[0126] This high solubility provides notable advantages. Because the salt remains in solution longer, a reactor may operate at higher conversions. EG concentrations can therefore be increased even further via solvent looping, which significantly lowers the distillation energy requirement. A fully soluble salt also enables inline filtration and recycling of oligomers to the reactor, which could push conversions higher. Lastly, most “continuous” designs for enzymatic depolymerization of PET involve a constant feed of PET and a fully soluble stream of TPA salt. The advantage of these aliphatic ammonium salts over amTPA here is that concentrations of PET, TPA, and EG could all be significantly increased without fouling of the pumping / filtration equipment necessary for continuous operation.

[0127] Further, both butylammonium TPA (BATPA) and diethylammonium TPA (DEATPA) are insoluble in acetone, and it has been found that a concentrated aqueous salt solution of either can be precipitated effectively by slow addition to vigorously stirred acetone. This observation potentially provides two process routes. The key parameters for the antisolvent are water miscibility and boiling point. Other solvents that may perform well in addition to acetone and / or in place of acetone include at least one of isopropanol, ethanol, methanol, tetrahydrofuran, and / or acetonitrile. It is preferable that an anti-solvent (e.g., acetone) boils below water to bring any energetic benefit to the process, and it must be able to effectively disperse in water to act as an effective anti-solvent.

[0128] First, from PETase depolymerization: In some embodiments of the present disclosure, a soluble enzymatic depolymerization product may be precipitated in acetone after filtration and decolorization. This gives a solid salt that could be dried and thermolyzed simultaneously at -130-160 °C. The residual solution would contain water, acetone, and EG. It may then be possible to perform reactive extraction directly on this mixture using a similar method reported in PROV / 23-07, and we are currently investigating this possibility. Instead of additional butanal, a process may be carried out using the residual acetone as the reactive extractant. The entire solution could be stirred over an Amberlyst (or similar) solid acid catalyst and the acetal product (2, 2-dimethyl- 1,3 -dioxolane) from EG+acetone could be distilled (BP. 93 °C) to isolate the EG via the reactive distillation process in PROV / 23-07, albeit with a more precise distillation setup to reduce water carryover.

[0129] Second, from other PET depolymerizations: As long as the product of the reaction is TPA, the following method may apply (i.e., acetolysis, but not methanolysis or glycolysis of PET). An impure mixture of TPA with water insoluble products could be taken up in a solution of amine / water or even pure amine (if TPA is sufficiently soluble in the pure amine). This could be precipitated in acetone, and the resulting salt dried and thermolyzed as above. While dissolved, inorganic and other insoluble impurities could be filtered. The precipitation itself may be able to separate trace organic impurities as well. This is of relevance to textile recycling, where the PET is almost always contaminated with inorganic material and other degradation products from nylon and polyurethane.

[0130] Figure 8 illustrates a method 100 for separating terephthalic acid (TPA) from an aqueous mixture that is rich in TPA, i.e., a TPA-rich stream 103, to form a stream of concentrated or pure TPA, i.e., TPA stream 142, and an aqueous mixture that is lean in TPA, i.e., TPA-lean stream 134, according to some embodiments of the present disclosure. As described herein, a TPA-rich stream 103 may be generated by the deconstruction of polyethylene terephthalate (PET), resulting in the forming of PET deconstruction products including TPA, ethylene glycol (EG). In some embodiments of the present disclosure, deconstruction of PET to form TPA and EG may be accomplished enzymatically, chemically, thermally, or by a combination of these routes. Reaction 1 illustrates the deconstruction reaction of PET to produce TPA and EG. Reaction 1

[0131] Although Reaction 1 illustrates the deconstruction of PET, the methods described herein may also be applied to deconstruct other polymers and / or resins including, polybutylene terephthalate, polypropylene terephthalate, polyethylene terephthalate glycol, poly(cyclohexylene dimethylene terephthalate glycol) (PCTG), polyethylene glycol 1,4- cyclohexane dimethylene isosorbide terephthalate) (PEICT), and the polymer resulting from the copolymerization of TPA, EG, and tetramethyl cyclobutanediol (PET-TMCD)

[0132] Referring again to Figure 8, the method 100 illustrated utilizes a cation forming molecule (CFM), acid-base chemistry, and the manipulation of solubilities for separating a pure and / or concentrated TPA stream 142 from a starting TPA-rich stream 103. As shown herein, primary amines (RNEE where R is a hydrocarbon group) and / or secondary amines (R2NH where R is a hydrocarbon group) may be utilized effectively as CFMs to separate and recover TPA from a TPA-rich stream. Reaction 2 illustrates the generalized process. The reaction is shown as a reversible equilibrium reaction, for which the direction of reaction depends upon, among other things, the concentrations of the respective reactants and products, the pKa of the reactants, the temperature of the solution in which the reaction is occurring, and the pH of the solution. In some embodiments of the present disclosure, the equilibrium reaction may proceed to full conversion to the dianion or incomplete conversion to the dianion. Further, Reaction 2 is shown for illustrative purposes and is not intended to be limiting.

[0133] Reaction 2

[0134] Referring to Figure 8, a method 100 may proceed through several steps, which are described here broadly and in more detail below. In brief, the exemplary method 100 begins with (excluding a number of pre-processing steps that are not shown) the forming 110 of a terephthalate salt 112 resulting from the combining of TPA in a starting stream, e.g., a TPA- rich stream 103, with a CFM 105. The forming 110 of such a salt 112 may be performed before and / or after the removal of any solids initially present in the TPA-rich stream; e.g., hydrolysis enzymes. Once the terephthalate salt 112, e.g., an ammonium terephthalate salt, is formed, the next step in the method 100 is to remove the terephthalate salt from the non-solid aqueous components remaining from the original TPA-rich stream 103. This is achieved by precipitating 120 the TPA salt, resulting in the forming of a suspension 122 of solid TPA salt suspended in the aqueous components remaining from the original TPA-rich stream 103. As described in detail below, the precipitating 120 of a soluble terephthalate salt from stream 112 to form solid terephthalate salt in stream 122 may be achieved by various techniques, that either lower the salt’s solubility in the aqueous mixture and / or raise its concentration above its solubility limit. Among other options, precipitating 120 a terephthalate salt may be achieved by lowering the temperature of stream 112 and / or by adding a precipitating agent to stream 112, aspects that are described in more detail below.

[0135] Referring again to Figure 8, with the terephthalic salt precipitated, it may then be separated from the remaining aqueous components in a removing 130 step, resulting in the forming of a TPA-lean stream 134 (and / or a TPA-free stream), which may be recycled back to the PET deconstruction reactor (not shown) and a stream 132 of the terephthalate salt in a solid form. The removing 130 of a solid terephthalate salt 132 from an aqueous phase may be achieved by any suitable solids / liquid separation unit operation, including filtration and / or centrifugation. In some embodiments of the present disclosure, once removed from the aqueous phase, a solid terephthalate salt 132 may be treated in an optional washing / cleaning step (not shown) to remove any residual unwanted materials from the salt. Regardless, with the solid terephthalate salt 132 in hand, the method 100 may proceed with treating 140 the solid terephthalate salt 132 to form a pure and / or concentrated stream of TPA 142 and a pure and / or concentrated stream of the CFM 144. In some embodiments of the present disclosure, treating 140 may involve thermally degrading (i.e., heating) 140A the solid terephthalate salt 132 resulting in the CFM volatilizing to be condensed as a pure or nearly pure liquid stream of CFM 144, and leaving behind a pure / concentrated solid stream of TPA 142. As a result, the separated TPA stream 142 may be recovered and reused to produce next generation TPA-containing polymers and / or resins and the separated CFM stream 144 may be recycled to the forming 100 step of the method 100.

[0136] Some additional details on the aspects briefly described above are described below. Referring again to Reaction 2 and Figure 8, TPA may be combined with a CFM 105, e.g., an amine, under conditions (e.g., suitable temperatures and concentrations) that enable TPA to deprotonate to form its anion, terephthalate, and the CFM 105, e.g., an amine, to protonate to form an ammonium ion. The anion and ammonium cation may then form their corresponding salt, for example, n-butylammonium terephthalate (from the primary amine n-butylamine as the CFM) or diethylammonium terephthalate (from the secondary amine diethylamine as the CFM). Once the ammonium terephthalate salt is formed, it may be separated from the other components contained in the TPA -rich stream 103 to yield the TPA -lean stream 134, which may then be recycled to the unit operation performing the PET deconstruction (not shown), and a TPA rich and / or pure stream 142 for eventual reuse of the recovered TPA, e.g., synthesizing PET and / or other useful polymers. An additional advantage to the method 100 illustrated in Figure 8, is that the CFM 105 originally combined with the TPA-rich stream 103 may also be recovered as a concentrated and / or pure CFM stream 144, enabling recycle (not shown) back to the forming 110 step.

[0137] Referring again to Figure 8, in some embodiments of the present disclosure, a terephthalate salt 112 may be created in a forming 110 step, in which a TPA-rich stream 103 is contacted and / or mixed with the CFM 105. For the example of any enzymatic PET deconstruction process completed in a batch reactor (not shown), a volume of liquid may be continuously and / or semi- continuously removed from the reactor. This stream, although having a high concentration of soluble TPA, may also contain solids such as valuable hydrolysis enzymes. Therefore, in some embodiments of the present disclosure, a solids-containing TPA-rich stream may be processed to remove the solids, enabling the capture and recycle of the enzyme back to the PET deconstruction reactor and the creation of a solids-free TPA-rich stream 103. Such a separation of solids from a solids-containing TPA-rich stream to form a solid enzyme stream for recycle to the PET deconstruction reactor and a solids-free TPA-rich stream 103 for further processing to yield a recovered TPA stream 142 may be achieved by filtration and / or centrifugation. In some embodiments of the present disclosure, a rotating ceramic disc filtration system may be utilized to remove enzymes from a solids-containing TPA-rich stream with recycle of the recovered enzymes back to the PET deconstruction reactor.

[0138] Referring again to Figure 8, in some embodiments of the present disclosure, a solids-free TPA- rich stream 103 may be combined with a CFM 105 to form a terephthalate salt 112 in a forming 110 step that is separate from a PET deconstruction reactor (not shown). For example, the forming 110 of a terephthalate salt 112 may be achieved by combining a TPA-rich stream 103 with a CFM 105 in an appropriate unit operation such as a stirred-tank reactor and / or packed- bed reactor that is separate and distinct from the PET deconstruction reactor. A stirred-tank reactor may include some form of mechanical mixing, whereas a packed-bed reactor may be filled with static mixing elements to promote the contacting / mixing of a CFM 105 with a TPA- rich stream 103.

[0139] However, in some embodiments of the present disclosure, the forming 110 of a terephthalate salt, by the combining of terephthalic acid and a CFM may be at least partially achieved in the PET deconstruction reactor itself (not shown). For the example of enzymatic hydrolysis of PET, as TPA is generated, a CFM may be added directly to the PET deconstruction reactor and mixed with the enzyme -containing aqueous mixture, e.g., fermentation broth, resulting in the forming of a terephthalate salt within the PET deconstruction reactor. Once formed, a small stream of the reactor contents may be continuously and / or semi-continuously removed from the reactor and subsequently processed to separate the solid enzyme for recycle back to the PET deconstruction reactor, thereby forming a TPA-rich stream 103.

[0140] In addition, although the examples given above describe forming a terephthalate salt, e.g., an ammonium terephthalate, by adding a CFM to a TPA-rich stream containing soluble terephthalate is an embodiment of the present disclosure, in some embodiments of the present disclosure, TPA may be present in a TPA-rich stream in a solid form, e.g., a suspension of TPA in an aqueous mixture or as a solid. Such an aqueous solid suspension or solid fraction of TPA may be combined with a second aqueous mixture containing the CFM, resulting in the formation of terephthalate salt solubilized in the resultant combined aqueous stream. This mixture could be further processed, e.g. filtration to remove insoluble impurities, treatment by chemical chelators to remove soluble impurities or crystallization / ion-exchange to remove soluble impurities. In some embodiments of the present disclosure, a cation forming molecule (CFM) suitable for the methods described herein may be described as having, when protonated (i.e., the conjugate acid of the cation forming molecule), a pKa between 5 and 14 or between 6 and 10 as measured at 25 °C in water. In some embodiments of the present disclosure, a cation forming molecule (CFM) suitable for the methods described herein may be characterized by the physical properties of the solid salt that it forms with terephthalate. For example, a CFM may form a solid salt with terephthalate that degrades to form the CFM in a gas phase and TPA in a solid phase when the solid salt, e.g., an ammonium terephthalate, is heated to a temperature between 100 °C and 270 °C or between 120 °C and 190 °C.

[0141] In some embodiments of the present disclosure, a cation forming molecule may include at least one of an amine, an imine, an amidine, a guanidine, some other suitable organic base, or a combination thereof. An amine CFM may include at least one of a primary amine, a secondary amine, a tertiary amine, or a combination thereof. Further, an amine CFM may include at least one of an alkylamine, an arylamine, a cyclic amine, or a combination thereof. Examples of alkylamines suitable for use as CFMs in the methods described herein include at least one trimethylamine, n-butylamine, diethylamine, i-propylamine, t-butylamine, benzylamine, ethanolamine, diethanolamine, cyclohexylamine, N,N-diethylmethylamine, N,N- dimethylethylamine, diisopropylethylamine, or a combination thereof. Examples of suitable cyclic amine CFMs include at least one of pyrrolidine, piperidine, morpholine, or a combination thereof.

[0142] In some embodiments of the present disclosure, the TPA present in a TPA-rich stream may be at a concentration between 1 g / liter and 10,000 g / liter or between 10 g / liter and 4000 g / liter or between 250 g / liter and 2500 g / liter. In some embodiments of the present disclosure, the adding of a cation forming molecule to a TPA-rich stream may result in the forming of a terephthalate salt in at least one of a dissolved state, a solid state, or a combination thereof. In some embodiments of the present disclosure, the adding of a cation forming molecule to a TPA-rich stream may result in the forming of a solid terephthalate salt suspended in water.

[0143] As stated above, in some embodiments of the present disclosure precipitating a terephthalate salt from water may be performed by lowering the solubility of the salt in the aqueous solution containing the salt. For example, the solubility of terephthalate salt may be lowered by at least one of adding a precipitating agent to a TPA-rich stream containing the salt, cooling the TPA- rich stream containing the salt, increasing the concentration of the TPA-rich stream containing the salt, or combinations thereof. In some embodiments of the present disclosure, a precipitating agent for lowering the solubility of a terephthalate salt in an aqueous stream is a water miscible solvent, such as polar solvents, including ketones and / or alcohols. Examples of ketones suitable for use as precipitating agents for precipitating terephthalate salts include acetone methylethyl ketone, 2-pentanone, 2-hexanone, or combinations thereof. Examples of alcohols suitable for use as precipitating agents for precipitating terephthalate salts include methanol, ethanol, iso-propanol, or combinations thereof. Other possible precipitating agents include acetonitrile, dimethyl sulfoxide, and / or dimethylformamide.

[0144] In some embodiments of the present disclosure, a terephthalate salt may be precipitated from an aqueous stream by cooling the aqueous stream to a temperature between -20 °C and 70 °C or between 0 °C and 25 °C. In some embodiments of the present disclosure, a terephthalate salt may be precipitated from an aqueous stream by increasing the salt’s concentration by removing water from the aqueous stream. Water may be removed by at least one of the following methods: evaporation (e.g., by heating or reducing pressure or both), reverse osmosis, and / or membrane separation. In some embodiments of the present disclosure, a terephthalate salt may be precipitated by first evaporating water from the aqueous stream containing the salt followed by cooling the concentrated stream to below the stream’s salt solubility limits.

[0145] In some embodiments of the present disclosure, a precipitated salt may be removed from a suspension of the salt in water by at least one of filtration, centrifugation, or a combination thereof. In some embodiments of the present disclosure, the removing of a solid terephthalate salt from an aqueous stream, e.g., suspension 122, may be performed at a temperature between 20 °C and 80 °C.

[0146] Referring again to Figure 8, in some embodiments of the present disclosure, the degrading 140A and separating 140B of a treating 140 step may be performed simultaneously or nearly simultaneously. Further, although the methods described herein focus on the recovery of EG and / or TPA, in some embodiments of the present disclosure similar methods may be utilized to recover EG and / or TPA and oligomers of EG and / or TPA. An example of an oligomer of EG and TPA is as follows, where n may be between 1 and 10. In some embodiments of the present disclosure, such oligomers may at least partially form salts with cation forming molecules, which may then be subsequently separated from a reaction media, as described above for TPA.

[0147] Experimental Results - TPA recovery from PET deconstruction by salt formation:

[0148] General procedures for the synthesis of ammonium terephthalate salts: Terephthalic acid (TPA) salts were prepared via one of four procedures based on the solubility of the salt in water and its propensity to form a filterable solid when triturated in acetone. The procedures are presented below in “priority order,” where procedure A was tested on each combination and only if it failed was procedure B tried, and C was tested only upon failure of B (and so forth). No specific effort was made to optimize the amount of amine used in the preparation of the synthetic terephthalate salts. All salts were dried under vacuum at room temperature for 24 hours prior to evaluation.

[0149] Depending on the basicity of the amine, some isolated salts may contain less than the anticipated 2.0 equivalents of incorporated cation. The degree of amine incorporation, and thus the salts true molecular weight, was evaluated by 'H NMR and TGA. Percent yields are calculated based on this experimentally determined MW.

[0150] Procedure A: solvent-free: To a known quantity of terephthalic acid, excess amine (>3 eq.) was added dropwise. The mixture was agitated with a wooden applicator until no exotherm was observed. The resulting salt was washed with acetone into a filter and dried for 15 minutes.

[0151] Procedure B: aqueous, with acetone precipitation: TPA was suspended in deionized water and excess amine (>2.5 eq.) was added dropwise. The solution was stirred until all solids were dissolved at which point it was added dropwise to vigorously stirred acetone. The suspension was stirred for 30 minutes, filtered, washed with additional acetone, and dried over the filter for 15 minutes.

[0152] Procedure C: aqueous with no precipitation: TPA was suspended in water and excess amine (>3 eq.) was added dropwise. Once all solids were dissolved, the water and excess amine was evaporated under a stream of nitrogen.

[0153] Procedure D: biphasic aqueous: TPA was suspended in water solvent and excess amine (3-5 eq.) was added dropwise. Once all solids were dissolved, a portion of the solvent and excess amine were removed under a stream of air. Acetone was then added and the suspension stirred vigorously for 30 minutes, filtered, washed with additional acetone, and dried over the filter for 15 minutes. Trimethylammonium terephthalate (MejNH -TPA): Synthesized via procedure C. TP A was dissolved in a 45 wt% solution of trimethylamine in water. The solution was evaporated to afford trimethylammonium terephthalate (Mc NH-TPA).

[0154] Triethylammonium terephthalate (EtsNH-TPA): Synthesized via procedure D using dichloromethane as the solvent. TPA (720 mg) was suspended in 8 mL DCM and triethylamine (2.0 mL) was added. The salt (1.117 g) was recovered as a white powder. n-Butylammonium terephthalate (n-BuNHs-TPA): Synthesized via procedure A. TPA (3.0513 g, 18.37 mmol) was reacted with 9 mL w-butylaminc (7.5 eq.). Once the amine was no longer consumed, the salt was washed with acetone to afford w-butylammonium terephthalate with 2.0 eq. amine (TGA = 2.02, NMR = 2.0) incorporated (5.5136 g, 17.65 mmol, 96% yield).

[0155] Diethylammonium terephthalate (Et2NH2-TPA) : Synthesized via procedure B. TPA (3.0272 g, 18.22 mmol) was reacted with 5.6 mL diethylamine (3.0 eq). Trituration in acetone afforded the salt with 2.0 eq amine (TGA = 1.97, NMR = 2.0) incorporated (4.8500 g, 15.5 mmol, 85% yield).

[0156] Iso-propylammonium terephthalate (i-PrNPD-TPA): Synthesized via procedure A. TPA (1.3602 g, 8.19 mmol) was reacted with 6.1 mL isopropylamine (5.2 eq). Washing with acetone afforded the salt with 2.0 eq. amine (TGA = 1.99, NMR = 2.0) incorporated (2.3103 g, 8.12 mmol, 99% yield).

[0157] Tert-hutylammonium terephthalate (t-Bu-TPA): Synthesized via a modified version of procedure C. TPA (2.7315 g, 16.44 mmol) was suspended in 10 mL water and 5 mL tertbutylamine (3.5 eq.) was added. The mixture was stirred for 30 minutes and gradually formed a thick slurry with the insoluble salt product. This was transferred to vigorously stirred acetone and residual washed from the vial with additional acetone. The resulting slurry was filtered to afford the salt with 1.95 eq. amine (TGA = 1.86, NMR = 2.0) incorporated (5.0436 g, 16.14 mmol, 98% yield).

[0158] Benzylammonium terephthalate (BnNED-TPA): Synthesized via a modified version of procedure C. TPA (1.0387 g, 6.25 mmol) was suspended in 10 mL water and 4 mL (5.9 eq.) benzylamine was added. The mixture was stirred for 60 minutes and formed a thick slurry with the largely insoluble product. This was transferred to vigorously stirred acetone and residual washed from the vial with additional acetone. The resulting slurry was filtered to afford the salt with 2.0 eq. amine (TGA = 1.92, NMR = 2.2) incorporated (2.0577 g, 5.41 mmol, 87% yield). Pyrrolidinium terephthalate (Pyr- -TPA): Synthesized via a modified version of procedure C. TPA (2.6102 g, 15.71 mmol) was suspended in 10 mL water and 5.0 mL pyrollidine (3.9 eq.) was added dropwise. The salt was recovered by first adding this solution to vigorously stirred acetone (200 mL), decanting off the top layer from resulting biphasic mixture, then adding the oily bottom layer containing the salt to another 250 mL of vigorously stirred acetone. Upon agitating for 30 minutes, the oil had been dispersed to a fine white powder which could be collected by filtration to yield the salt.

[0159] Piperidinium terephthalate (Pip-TPA): Synthesized via procedure B. TPA (1.1103 g, 6.68 mmol) was suspended in 10 mL water and reacted with 4.0 mL piperidine (6.0 eq.). Trituration in acetone yielded the salt with 2.0 eq. amine incorporated (2.192 g, 6.52 mmol, 98% yield).

[0160] Morpholinium terephthalate (Mph-TPA): Synthesized via procedure B. TPA (1.4666 g, 9.10 mmol) was suspended in 10 mL water and reacted with 5 mL morpholine (6.4 eq.). Trituration in acetone yielded the salt with 2.0 eq. amine.

[0161] Ethanolammonium terephthalate (Eth-TPA): Synthesized via procedure B. TPA (1.5141 g, 9.11 mmol) was suspended in 10 mL water and reacted with 4 mL ethanolamine (7.3 eq.). Trituration in acetone yielded the salt (2.4419 g, 8.47 mmol, 93% yield) with 2.0 eq. amine (TGA = 1.89, NMR = 2.1) incorporated.

[0162] The physical properties of some of these cation forming molecules are tabulated in Table 4 below.

[0163] Table 4. Cation forming molecule physical properties Examples:

[0164] Example 1. A method for generating enriched reaction media, the method comprising: providing a first amount of polyethylene terephthalate) (PET) to a reaction chamber; performing depolymerization of the PET, thereby generating a first reaction media; adding a second amount of PET to the first reaction media; and performing depolymerization on the combined second amount of PET and the first reaction media, thereby generating an enriched hydrolysis reaction media.

[0165] Example 2. The method of Example 1, wherein depolymerization of the PET generates ethylene glycol (EG) components and terephthalic acid (TP A) components.

[0166] Example 3. The method of either Example 1 or Example 2, wherein the combined second amount of PET and first reaction media are provided to the reaction chamber.

[0167] Example 4. The method of any one of Examples 1-3, wherein the method comprises a fed- batch process within the reaction chamber.

[0168] Example 5. The method of any one of Examples 1-4, wherein the combined second amount of PET and reaction media are combined prior to being provided to the reaction chamber.

[0169] Example 6. The method of any one of Examples 1-5, wherein the combined second amount of PET and the reaction media are combined after being separately provided to the reaction chamber.

[0170] Example 7. The method of any one of Examples 1-6, wherein the depolymerization of the PET comprises an enzymatic hydrolysis process.

[0171] Example 8. The method of Example 1-7, wherein the enzymatic hydrolysis process comprises providing one or more enzymes to the enzyme hydrolysis reaction chamber and performing enzymatic depolymerization of the PET using the one or more enzymes, thereby generating a first reaction media.

[0172] Example 9. A method of TPA precipitation through enriched hydrolysis reaction media, the method comprising: providing a first enriched hydrolysis reaction media, wherein the enriched hydrolysis reaction media comprises a first amount of ethylene glycol and a first amount of terephthalic acid components; initiating a media enrichment process by inputting the first enriched hydrolysis reaction media into a PET enzymatic hydrolysis reaction process, thereby generating a second enriched hydrolysis reaction media by providing additional ethylene glycol and terephthalic acid to the first enriched hydrolysis reaction media; and repeating the media enrichment process until at least a portion of terephthalic acid (TPA) precipitate out of it associated enriched hydrolysis reaction media.

[0173] Example 10. The method of Example 9, wherein PET is provided to the PET enzymatic hydrolysis reaction process.

[0174] Example 11. The method of either Example 9 or Example 10, wherein the PET is added prior to the initiation of the PET enzymatic hydrolysis reaction process.

[0175] Example 12. The method of any one of Examples 9-11, wherein the PET is added during the PET enzymatic hydrolysis reaction process.

[0176] Example 13. The method of Example 9-12, wherein the PET depolymerization process comprises an enzymatic hydrolysis reaction process.

[0177] Example 14. The method of any one of Examples 9-13, wherein enzymes are provided to the PET enzymatic hydrolysis reaction process.

[0178] Example 15. The method of any one of Examples 9-14, wherein the enzymes are added prior to the initiation of the PET enzymatic hydrolysis reaction process.

[0179] Example 16. The method of any one of Examples 9-15, wherein the enzymes are added during the PET enzymatic hydrolysis reaction process.

[0180] Example 17. A method of increasing efficiency of ethylene glycol recovery through enriched reaction media, the method comprising: providing a first enriched reaction media, wherein the enriched reaction media comprises a first amount of ethylene glycol; initiating a media enrichment process by inputting the first enriched reaction media into a PET depolymerization reaction process, thereby generating a second enriched reaction media by providing additional ethylene glycol to the first enriched reaction media; repeating the media enrichment process one or more times, thereby generating an ethylene glycol-enriched hydrolysis reaction media; providing the ethylene glycol-enriched reaction media to one or more distillation columns; and recovering an increased amount of ethylene glycol product from the distillation of the ethylene glycol-enriched reaction media as compared to the distillation of a similar amount of unenriched reaction media.

[0181] Example 18. The method of Example 17, wherein the PET is provided to the PET depolymerization reaction process.

[0182] Example 19. The method of either Example 17 or Example 18, wherein the PET is added prior to the initiation of the PET depolymerization reaction process. Example 20. The method of any one of Examples 17-19, wherein the PET is added during the PET depolymerization reaction process.

[0183] Example 21. The method of any one of Examples 17-20, wherein the PET depolymerization reaction process comprises an enzymatic hydrolysis reaction process.

[0184] Example 22. The method of any one of Examples 17-21, wherein enzymes are provided to the PET enzymatic hydrolysis reaction process.

[0185] Example 23. The method of any one of Examples 17-22, wherein the enzymes are added prior to the initiation of the PET enzymatic hydrolysis reaction process.

[0186] Example 24. The method of any one of Examples 17-23, wherein the enzymes are added during the PET enzymatic hydrolysis reaction process.

[0187] Example 25. A method of purifying TPA from a PET depolymerization product mixture, the method comprising: providing a hydrolytic solution comprising PET depolymerization products, wherein the PET depolymerization products comprise TPA; adding an ammonium- based component to the hydrolytic solution; and undergoing conditions of thermolysis, thereby generating a recyclable ammonia and TPA salt precipitate.

[0188] Example 26. A method of pre-treating PET substrates, the method comprising: extruding PET, thereby forming extruded strands of PET; rapidly cooling the extruded PET strands; and chopping the extruded PET strands using a rotating knife unit.

[0189] Example 27. A method of retaining enzymes within a hydrolysis reactor system, the method comprising: providing a hydrolysis reactor system, wherein the hydrolysis reactor system comprises a hydrolysis reactor and a rotating ceramic disc filtration component, wherein the hydrolysis reactor is communicatively coupled to the rotating ceramic disc filtration component; generating a PET depolymerization hydrolytic solution at the enzymatic hydrolysis reactor system, wherein the PET depolymerization hydrolytic solution comprises enzymes and PET depolymerization products; providing the PET depolymerization hydrolytic solution to the rotating ceramic disc filtration component; processing the PET depolymerization hydrolytic solution at the rotating ceramic disc filtration component, thereby generating a retentate, wherein the retentate comprises at least a portion of the enzymes from the PET depolymerization hydrolytic solution; and recycling the retentate back into the hydrolysis reaction. Example 28. A method of isolating ethylene glycol via use of an acetal, the method comprising: providing an aqueous solution comprising ethylene glycol; reacting the ethylene glycol with an immiscible aldehyde over an acid catalyst, thereby generating acetal; decanting the resulting mixture into unreacted aldehyde; a first layer comprising unreacted ethylene glycol; and an organic layer comprising the acetal; transferring the organic layer to a reactive distillation system; and isolating the ethylene glycol through use of one or more distillation columns within the reactive distillation system.

[0190] Example 29. A method of any of the previous Examples, wherein the enzyme is a hydrolase.

[0191] Example 30. A method of any of the previous Examples, wherein the enzyme has hydrolase activity of greater than 90% conversion efficiency.

[0192] Example 31. A method of any of the previous Examples, wherein the enzyme is a PET hydrolase.

[0193] Example 32. A method comprising: a first contacting of a mixture comprising TPA with an amine, wherein the first contacting results in the formation of a salt of the TPA and the amine; a second contacting of the mixture containing the salt with a polar solvent, wherein the second contacting results in the formation of a precipitation of the salt, forming a solid salt; separating the solid salt from the mixture; and thermally treating the solid salt, resulting in the forming of the amine and TPA.

[0194] Example 33. A method comprising: forming a salt comprising terephthalic acid (TPA) and a cation; precipitating the salt; removing the salt; and treating the salt resulting in TPA separated from a cation forming molecule.

[0195] Example 34. The method of Example 33, wherein the forming of the salt is performed by adding a cation forming molecule to a TPA-rich stream comprising TPA and water.

[0196] Example 35. The method of either Example 33 or Example 34, wherein the conjugate acid (i.e., protonated form of the CFM) of the cation forming molecule has a pKa between 5 and 14 or between 6 and 10 when measured at 25 °C in pure water.

[0197] Example 36. The method of any one of Examples 33-35, wherein the salt, when in a solid state, is capable of thermally degrading to form TPA and the cation forming molecule, when heated to a temperature between 100 °C and 270 °C or between 120 °C and 190 °C. Example 37. The method of any one of Examples 33-36, wherein the cation forming molecule comprises at least one of an amine, an imine, an amidine, a guanidine, or some other suitable organic base.

[0198] Example 38. The method of any one of Examples 33-37, wherein the amine comprises at least one of a primary amine, a secondary amine, a tertiary amine, or a combination thereof.

[0199] Example 39. The method of any one of Examples 33-38, wherein the amine comprises at least one of an alkylamine, an arylamine, a cyclic amine, or a combination thereof.

[0200] Example 40. The method of any one of Examples 33-39, wherein the alkylamine comprises at least one trimethylamine, n-butylamine, diethylamine, i-propylamine, t-butylamine, benzylamine, ethanolamine, diethanolamine, cyclohexylamine, N,N-diethylmethylamine, N,N-dimethylethylamine, diisopropylethylamine, or a combination thereof

[0201] Example 41. The method of any one of Examples 33-40, wherein the cyclic amine comprises at least one of pyrrolidine, piperidine, morpholine, or a combination thereof.

[0202] Example 42. The method of any one of Examples 33-41, wherein, before the forming, the TPA is dissolved in the TPA-rich stream.

[0203] Example 43. The method of any one of Examples 33-42, wherein the TPA is present in the TPA-rich stream at a concentration between 1 g / liter and 10,00 g / liter, or between 50 g / liter and 4000 g / liter, or between 250 g / liter and 2500 g / liter.

[0204] Example 44. The method of any one of Examples 33-43, wherein, the adding of the cation forming molecule results in the forming of the salt in at least one of a dissolved state or a solid state.

[0205] Example 45. The method of any one of Examples 33-44, wherein precipitating the salt from the TPA-rich stream results in a suspension comprising the salt in a solid state and water.

[0206] Example 46. The method of any one of Examples 33-45, wherein the precipitating is performed by lowering the solubility of the salt in the TPA-rich stream.

[0207] Example 47. The method of any one of Examples 33-46, wherein the lowering of the solubility is performed by at least one of adding a precipitating agent to the TPA-rich stream, cooling the TPA-rich stream, or increasing the concentration of the TPA-rich stream, or a combination thereof. Example 48. The method of any one of Examples 33-47, wherein the precipitating agent comprises at least one of a solvent which is miscible with water.

[0208] Example 49. The method of any one of Examples 33-48, wherein the solvent comprises at least one of a ketone, an alcohol, or a combination thereof.

[0209] Example 50. The method of any one of Examples 33-49, wherein the ketone comprises at least one of acetone, methylethyl ketone, 2-pentanone, 2-hexanone, or a combination thereof.

[0210] Example 51. The method of any one of Examples 33-50, wherein the TPA-rich stream is cooled to a temperature between -20 °C and 70 °C or between 0 °C and 25 °C.

[0211] Example 52. The method of any one of Examples 33-51, wherein the TPA-rich stream concentration is increased by at least one of heating the TPA-rich stream, by applying a reduced pressure to the TPA-rich stream, by concentrating with membrane nano-filtration.

[0212] Example 53. The method of any one of Examples 33-52, wherein removing the salt from the suspension results in a TPA-lean stream and a solid salt substantially free of liquid.

[0213] Example 54. The method of any one of Examples 33-53, wherein treating the solid salt results in a first stream comprising TPA and a second stream comprising the cation forming molecule.

[0214] Example 55. The method of any one of Examples 33-54, wherein the treating comprises degrading the solid salt to form TPA and the cation forming molecule.

[0215] Example 56. The method of any one of Examples 33-55, wherein the degrading is performed by heating the salt.

[0216] Example 57. The method of any one of Examples 33-56, further comprising separating the TPA from the cation forming molecule.

[0217] Example 58. The method of any one of Examples 33-57, wherein the heating results in the salt degrading to TPA in a solid state and the cation forming molecule in a gaseous state and the gaseous cation forming molecule is separated from the solid TPA.

[0218] Example 59. The method of any one of Examples 33-58, wherein the degrading and separating are performed simultaneously or nearly simultaneously.

[0219] Example 60. The method of any one of Examples 33-59, further comprising, prior to the forming, filtering a stream comprising TPA and an enzyme, resulting in the TPA-rich stream and a stream comprising the enzyme. Example 61. The method of any one of Examples 33-60, wherein the filtering comprises at least one of cross-flow filtration, dynamic filtration, or a combination thereof.

[0220] The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments, exemplary embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims. The specific embodiments provided herein are examples of useful embodiments of the present invention and it will be apparent to one skilled in the art that the present invention may be carried out using a large number of variations of the devicesand methods steps set forth in the present disclosure. As will be obvious to one of skill in the art, methods, and devices useful for the present methods can include a large number of optional composition and processing elements and steps.

[0221] The embodiments described herein should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0222] As used herein the term “substantially” is used to indicate that exact values are not necessarily attainable. By way of example, one of ordinary skill in the art will understand that in some chemical reactions 100% conversion of a reactant is possible, yet unlikely. Most of a reactant may be converted to a product and conversion of the reactant may asymptotically approach 100% conversion. So, although from a practical perspective 100% of the reactant is converted, from a technical perspective, a small and sometimes difficult to define amount remains. For this example of a chemical reactant, that amount may be relatively easily defined by the detection limits of the instrument used to test for it. However, in many cases, this amount may not be easily defined, hence the use of the term “substantially”. In some embodiments of the present invention, the term “substantially” is defined as approaching a specific numeric value or target to within 20%, 15%, 10%, 5%, or within 1% of the value or target. In further embodiments of the present invention, the term “substantially” is defined as approaching a specific numeric value or target to within 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, or 0.1% of the value or target.

[0223] As used herein, the term “about” is used to indicate that exact values are not necessarily attainable. Therefore, the term “about” is used to indicate this uncertainty limit. In some embodiments of the present invention, the term “about” is used to indicate an uncertainty limit of less than or equal to ±20%, ±15%, ±10%, ±5%, or ±1% of a specific numeric value or target. In some embodiments of the present invention, the term “about” is used to indicate an uncertainty limit of less than or equal to ±l%, ±0.9%, ±0.8%, ±0.7%, ±0.6%, ±0.5%, ±0.4%, ±0.3%, ±0.2%, or ±0.1% of a specific numeric value or target.

[0224] The foregoing discussion and examples have been presented for purposes of illustration and description. The foregoing is not intended to limit the aspects, embodiments, or configurations to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the aspects, embodiments, or configurations are grouped together in one or more embodiments, configurations, or aspects for the purpose of streamlining the disclosure. The features of the aspects, embodiments, or configurations, may be combined in alternate aspects, embodiments, or configurations other than those discussed above. This method of disclosure is not to be interpreted as reflecting an intention that the aspects, embodiments, or configurations require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment, configuration, or aspect. While certain aspects of conventional technology have been discussed to facilitate disclosure of some embodiments of the present invention, the Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate aspect, embodiment, or configuration.

Claims

CLAIMSWhat is claimed is:

1. A method comprising : forming a salt comprising terephthalic acid (TPA) and a cation; precipitating the salt; removing the salt; and treating the salt resulting in TPA separated from a cation forming molecule.

2. The method of claim 1, wherein the forming of the salt is performed by adding the cation forming molecule to a TPA-rich stream comprising TPA and water.

3. The method of claim 2, wherein a conjugate acid of the cation forming molecule has a pKa between 5 and 14 when measured at 25 °C in pure water.

4. The method of claim 3, wherein the salt, when in a solid state, is capable of thermally degrading to form TPA and the cation forming molecule, when heated to a temperature between 100 °C and 270 °C.

5. The method of claim 2, wherein the cation forming molecule comprises at least one of an amine, an imine, an amidine, a guanidine, or a combination thereof.

6. The method of claim 5, wherein the amine comprises at least one of a primary amine, a secondary amine, a tertiary amine, or a combination thereof.

7. The method of claim 5, wherein the amine comprises at least one of an alkylamine, an arylamine, a cyclic amine, or a combination thereof.

8. The method of claim 7, wherein the alkylamine comprises at least one trimethylamine, n-butylamine, diethylamine, i-propylamine, t-butylamine, benzylamine, ethanolamine, diethanolamine, cyclohexylamine, N,N -diethylmethylamine, N,N- dimethylethylamine, diisopropylethylamine, or a combination thereof9. The method of claim 7, wherein the cyclic amine comprises at least one of pyrrolidine, piperidine, morpholine, or a combination thereof.

10. The method of claim 2, wherein, before the forming, the TPA is dissolved in the TPA- rich stream.

11. The method of claim 10, wherein, the adding of the cation forming molecule results in the forming of the salt in at least one of a dissolved state or a solid state.

12. The method of claim 11, wherein precipitating the salt from the TPA-rich stream results in a suspension comprising the salt in a solid state and water.

13. The method of claim 12, wherein the precipitating is performed by lowering the solubility of the salt in the TPA-rich stream.

14. A method of TPA precipitation through enriched hydrolysis reaction media, the method comprising: providing a first enriched hydrolysis reaction media, wherein the enriched hydrolysis reaction media comprises a first amount of ethylene glycol and a first amount of terephthalic acid components; initiating a media enrichment process by inputting the first enriched hydrolysis reaction media into a PET enzymatic hydrolysis reaction process, thereby generating a second enriched hydrolysis reaction media by providing additional ethylene glycol and terephthalic acid to the first enriched hydrolysis reaction media; and repeating the media enrichment process until at least a portion of terephthalic acid (TPA) precipitate out of it associated enriched hydrolysis reaction media.

15. A method of isolating ethylene glycol, the method comprising: providing an aqueous solution comprising ethylene glycol; reacting the ethylene glycol with an immiscible aldehyde over an acid catalyst, thereby generating acetal; decanting the resulting mixture into unreacted aldehyde; a first layer comprising unreacted ethylene glycol; and an organic layer comprising the acetal; transferring the organic layer to a reactive distillation system; and isolating the ethylene glycol through use of one or more distillation columns within the reactive distillation system.

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