Recycling method for textile waste containing cellulose and polyester components

Abstract

The present invention relates to a method for recycling a textile waste (ST) comprising a cellulose component and a polyester component, comprising a depolymerization step 110, which comprises subjecting the textile waste (ST) to a depolymerization reaction by basic hydrolysis of said polyester component with a solvolysis mixture (MS) comprising an alkali metal hydroxide (IMA) and at least one water-soluble organic reaction solvent (SOIR), until obtaining a two-phase mixture (MB) comprising an initial solid phase (FSI) containing salts of terephthalic acid (SAT) and cellulose fibers and an initial liquid phase (FLI) containing a water-soluble organic reaction solvent (SOIR), a first step 210 of solid-liquid separation, which comprises removing at least a part of the initial liquid phase (FLI) from the two-phase mixture (MB), and a second step 220 of solid-liquid separation, which comprises removing at least a part of the initial liquid phase (FLI) from the two-phase mixture (MB), and a second step 230 of solid-liquid separation, which comprises removing at least a part of the initial liquid phase (FLI) from the two-phase mixture (MB), and a second step 240 of solid-liquid separation, which comprises removing at least a part of the initial liquid phase (FLI) from the two-phase mixture (MB), and a second step 250 of solid-liquid separation, which comprises removing at least a part of the initial liquid phase (FLI) from the two-phase mixture (MB), and a second step 260 of solid-liquid separation, which comprises removing at least a part of the initial liquid phase (FLI) from the two-phase mixture (MB), and a second step 270 of solid-liquid separation, which comprises removing at least a part of the initial liquid phase (FLI) from the two-phase mixture (MB), and a second step 280 of solid-liquid separation, which comprises removing at least a part of the initial liquid phase (FLI) from the two-phase mixture (MB), and a second step 290 of solid-liquid separation, which comprises removing at least a part of the initial liquid phase (FLI) from from the first step 220 of treatment with an organic solvent, in which the first step 220 is treated with an organic washing solvent (SOL) until one or more contaminants possibly present therein are removed and a purified solid phase (FSP) containing salts of terephthalates (SAT) and cellulose fibres is obtained; a second step 230 of solid-liquid separation, in which the purified solid phase (FSP) is separated from the organic washing solvent (SOL) and from one or more possible contaminants dissolved therein; and a step 240 of treatment with water, in which the purified solid phase (FSP) is contacted with wash water (AL) until the salts of terephthalates (SAT) contained therein are solubilised, and by removing the latter, a final solid phase (FSF) containing the cellulose fibres is obtained.

Description

Technical Field

[0001] The present invention relates to a method for recycling fiber waste containing a cellulose component (preferably cotton) and a polyester component.

Background Art

[0002] Currently, in the fiber field, it is known to use a mixed fabric that combines both natural fibers and synthetic fibers.

[0003] An example of such a fabric is the so-called "polycotton", which is a fabric containing cotton fibers and polyester fibers in various ratios and containing other possible substances such as dyes.

[0004] In addition to being the most common type of polyester fabric in the market, polycotton currently occupies a very important part of the entire fiber field available in the world market.

[0005] The large amount of polycotton produced every year poses the problem of how to recycle it with respect to both the cotton component and the polyester component. This problem is becoming increasingly serious, especially from the perspective of the so-called "circular economy".

[0006] To recycle polycotton, a process of mechanically separating cotton fibers from polyester fibers is known. However, these known solutions are not satisfactory because they cannot obtain polyester monomers and cannot remove possible contaminants that limit the possibility of reuse, such as dyes, from cotton.

Summary of the Invention

[0007] The main object of the present invention is to provide a method for recycling textile waste containing a cellulose component (preferably cotton) and a polyester component, which makes it possible to effectively separate the cellulose component from the polyester component and from any contaminants that may be present in the textile waste.

[0008] A further object of the present invention is that it can be applied to the industrial-scale recovery of cellulosic and / or polyester components contained in such textile waste.

[0009] Another object of the present invention is to provide a relatively simple, effective, and economical recycling method for textile waste containing cellulose components (preferably cotton) and polyester components.

[0010] Another objective is to obtain a method for recycling textile waste containing cellulose components (preferably cotton) and polyester components, which is relatively sustainable and allows for the effective use of auxiliary chemicals in the process.

[0011] These and other objectives of the present invention are achieved by a method for recycling textile waste containing cellulose and polyester components, the method being A depolymerization step includes providing fiber waste to a depolymerization reaction of polyester components by basic hydrolysis with an alkali metal hydroxide and at least one water-soluble organic reaction solvent until a two-phase mixture is obtained, comprising an initial solid phase containing terephthalate and cellulose fibers and an initial liquid phase containing a water-soluble organic reaction solvent; A first step of solid-liquid separation, comprising removing at least a portion of the initial liquid phase from the two-phase mixture, Following the first step of solid-liquid separation, the initial solid phase is treated with an organic washing solvent until one or more contaminants that may be present in the initial solid phase are removed to obtain a purified solid phase containing terephthalate and cellulose fibers. The purified solid phase is separated from the organic washing solvent and one or more possible contaminants dissolved therein in a second step of solid-liquid separation, A water treatment step comprising contacting the purified solid phase with washing water until the terephthalate contained therein is solubilized, and removing the latter to obtain a final solid phase containing cellulose fibers, Includes.

[0012] Advantageously, the solvolysis mixture used in the basic hydrolysis process may also contain reaction water.

[0013] Preferably, the organic washing solvent is Glycols (C2-C8) having 2-8 carbon atoms, Alcohols C1-C6 or mixtures of alcohols C1-C6, Ketones C3-C8 or a mixture of ketones C3-C8 Ether or a mixture of ether, Alkanes C5-C8 or mixtures of alkanes C5-C8 It is at least one of the substances, or contains at least one of them.

[0014] Preferably, the glycol is a glycol having a boiling point of less than 300°C.

[0015] Preferably, the glycol is selected from monoethylene glycol (MEG), diethylene glycol (DEG), triethylene glycol (TEG), and mixtures thereof. More preferably, the glycol is monoethylene glycol (MEG).

[0016] Preferably, alcohols C1 to C6 are selected from methanol (MeOH), ethanol (EtOH), isopropanol (i-PrOH), butanol (BuOH), and mixtures thereof.

[0017] Preferably, the C3-C8 ketones are selected from acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and mixtures thereof.

[0018] Preferably, the ether is selected from diethyl ether (Et2O), tetrahydrofuran (THF), and mixtures thereof.

[0019] Preferably, the C5-C8 alkanes are selected from hexane, heptane, octane, and mixtures thereof.

[0020] Advantageously, the water-soluble organic reaction solvent and the organic cleaning solvent are the same substance or contain the same substance.

[0021] Preferably, the alkali metal hydroxide is selected from sodium hydroxide (NaOH), potassium hydroxide (KOH), lithium hydroxide (LiOH), and mixtures thereof.

[0022] In an advantageous embodiment, the depolymerization reaction by basic hydrolysis is carried out with microwave assistance.

[0023] Advantageously, the method according to the invention includes a step of preparing the fibrous waste, which includes shredding the fibrous waste before the depolymerization step.

[0024] Preferably, the second step of solid-liquid separation includes separating the purified solid phase from the organic cleaning solvent and from any possible contaminants dissolved therein by evaporation.

[0025] Advantageously, the second step of solid-liquid separation includes separating the purified solid phase from the organic cleaning solvent and from any possible contaminants dissolved therein by evaporation at a pressure below atmospheric pressure.

[0026] Advantageously, the organic cleaning solvent used in the step of treating with an organic solvent comprises a part of a fresh organic cleaning solvent and a part of a recovered organic cleaning solvent obtained by separating it from the purified solid phase in the second step of solid-liquid separation of the process according to the invention, which is carried out before the step of treating with an organic solvent.

[0027] Advantageously, the step of treating with an organic solvent comprises one or more sub-steps of solid-solvent mixing in which the initial solid phase is added to and mixed with the organic cleaning solvent, followed in each case by a sub-step of solid-solvent separation in which the organic cleaning solvent is at least partially removed from the initial solid phase.

[0028] Preferably, the one or more sub-steps of solid-solvent mixing comprise two or more sub-steps of solid-solvent mixing, and the purity of the organic cleaning solvent used in the two or more sub-steps of solid-solvent mixing advantageously increases from the beginning to the end of the two or more sub-steps of solid-solvent mixing.

[0029] Advantageously, the organic cleaning solvent used at the end of the one or more sub-steps of solid-solvent mixing comprises a part of a fresh organic cleaning solvent and a part of a recovered organic cleaning solvent obtained by removing it from the purified solid phase in the second step of solid-liquid separation of the process according to the invention, which is carried out before that last of the one or more sub-steps of solid-solvent mixing.

[0030] Advantageously, the process according to the invention comprises a water removal step which comprises removing any washing water present therein from the final solid phase after the step 240 of treating with water.

[0031] Preferably, the step of removing water comprises removing any washing water present therein from the final solid phase by evaporation.

[0032] Advantageously, the step of removing water comprises removing any washing water present therein from the final solid phase by evaporation at a pressure lower than atmospheric pressure.

[0033] Advantageously, the wash water used in the water treatment step may include a portion of fresh wash water and a portion of recovered wash water removed from the final solid phase in a water removal step of the textile waste recycling method according to the present invention that has been performed in advance.

[0034] The water treatment step includes one or more substeps of solid-water mixing in which the purified solid phase is added to and mixed with water, each of which is followed by a substep of solid-water separation in which water is removed at least partially from the purified solid phase.

[0035] One or more substeps of solid-water mixing favorably include two or more substeps of solid-water mixing, and the purity of the washing water used in one or more substeps of solid-water mixing increases from the beginning to the end of one or more substeps of solid-water mixing.

[0036] Advantageously, the water used at the end of one or more substeps of solid-water mixing includes a portion of new wash water and a portion of water removed from the final solid phase, which is performed prior to the end of one or more substeps of solid-water mixing in the water removal step of the textile waste recycling method according to the present invention.

[0037] In one embodiment, during the step of treatment with water, the washing water is at least partially removed from the purified solid phase, and the removed washing water is subjected to a terephthalic acid precipitation step in which it reacts with an inorganic acid to form a suspension of initial terephthalic acid in an acidic aqueous solution. The method comprises a step of separating terephthalic acid, wherein the initial terephthalic acid is removed from the acidic aqueous solution, and the acidic aqueous solution is then subjected to a neutralization step of the method, in which the acidic aqueous solution is brought into contact with an alkali base to form an alkali metal and obtain a neutral aqueous solution. The method comprises subjecting the neutral aqueous solution to a recovery step, which comprises an electrolysis step and, optionally, a combination step, from which the same inorganic acid used in the terephthalic acid precipitation step and the same alkali base used in the neutralization step are obtained, and the inorganic acid thus obtained is used in a further step of the method according to the present invention, which is subsequently carried out, to precipitate terephthalic acid.

[0038] The features and advantages of the present invention will become more apparent from the following description, which is illustrative and not limiting, with reference to the attached schematic diagrams. [Brief explanation of the drawing]

[0039] [Figure 1] This is a flowchart illustrating the steps of an advantageous embodiment of the method according to the present invention. [Figure 2] This is a more detailed schematic diagram of one of the steps in the method shown in Figure 1. [Figure 3] This is a more detailed schematic diagram of one step in the method shown in Figure 1. [Figure 4] This is a more detailed schematic diagram of one step in the method shown in Figure 1. [Figure 5] This is a more detailed schematic diagram of one step in the method shown in Figure 1. [Figure 6] This is a more detailed schematic diagram of one step in the method shown in Figure 1. [Figure 7] This is a more detailed schematic diagram of one step in the method shown in Figure 1. [Figure 8] This is a schematic diagram of an advantageous embodiment of a reactor usable in the method according to the present invention. [Figure 9] This is a schematic diagram of a further advantageous embodiment of a reactor usable in the method according to the present invention. [Figure 10] This is a detailed flowchart illustrating some steps of a more advantageous embodiment of the method according to the present invention. [Modes for carrying out the invention]

[0040] Figure 1 shows a flowchart schematically illustrating various steps of an advantageous embodiment of the method according to the present invention.

[0041] The method according to the present invention includes a depolymerization step 110 in which fiber waste ST containing a cellulose component, such as cotton, and a polyester component is subjected to a depolymerization reaction of the polyester component by basic hydrolysis, and this reaction is referred to as the "depolymerization reaction" below.

[0042] The ratio of cellulose components to polyester components in the textile waste ST may vary, but preferably, the cellulose component (e.g., cotton) is 15% to 65% by weight of the textile waste ST.

[0043] The depolymerization reaction occurs by contact between the fiber waste ST and a solvolysis mixture MS containing potentially reaction water AR, alkali metal hydroxide IMA, and a water-soluble organic reaction solvent SOIR. The alkali metal hydroxide IMA may include, for example, sodium hydroxide NaOH and / or potassium hydroxide KOH and / or lithium hydroxide LiOH. Examples of the water-soluble organic reaction solvent SOIR are given below.

[0044] The depolymerization reaction is preferably microwave-assisted and preferably advantageously carried out in a microwave-type reactor 1 schematically shown in Figure 2.

[0045] An advantageous example of a microwave reactor 1 usable in the method according to the present invention is shown, for example, in European Patent No. 2736968, in the name of the same applicant as this application.

[0046] Further examples of advantageous embodiments of reactor 1 are schematically shown in Figure 8.

[0047] Such a reactor 1 may advantageously include a mixing device 2, a thermal control system 3, and a microwave generation and transport system 4.

[0048] Advantageously, the reactor 1 comprises a casing 5 that defines a reaction chamber 8 inside. The casing 5 is preferably substantially cylindrical and extends along and around a longitudinal axis A that is substantially horizontal when in use.

[0049] Please understand that during use, the casing 5, and by extension the reactor 1 itself, may be oriented in different directions, and therefore axis A may be vertical rather than horizontal, or may be inclined in various ways with respect to the horizontal plane (for example, with respect to the ground).

[0050] Advantageously, the casing 5 has side walls 6, for example, cylindrical, and a pair of end walls 7 located at both ends in the axial direction define the interior of the reaction chamber 8.

[0051] The casing 5 is advantageously composed of a material that is substantially opaque to microwave electromagnetic radiation and preferably corrosion-resistant.

[0052] Furthermore, the casing 5 is advantageously designed to withstand both internal overpressure and underpressure conditions relative to atmospheric pressure.

[0053] The reactor 1 is advantageously provided with one or more inlets and one or more outlets, each preferably defined by an opening formed in the casing 5, and configured to allow the introduction of various components involved in the depolymerization reaction into the reaction chamber 8, such as fiber waste ST, solvolysis mixture MS, and possible auxiliary components, as well as the removal of the depolymerization reaction products and possible residual elements from the reaction chamber 8.

[0054] In an advantageous embodiment as shown in Figure 8, the reactor 1 is provided with at least one inlet 9 for introducing the material to be processed in the reactor 1 (e.g., possibly shredded fiber waste ST), the solvolysis mixture MS, and possible auxiliary components into the reaction chamber 8.

[0055] In a more advantageous embodiment (not shown), the material to be processed, the solvolysis mixture, and possible auxiliary components may be introduced into reactor 1 through a separate, dedicated inlet.

[0056] Advantageously, reactor 1 is provided with at least one outlet 10 for removing the contents of reaction chamber 8 at the end of the depolymerization reaction.

[0057] Advantageously, the reaction chamber 8 houses a mixing device 2 that is rotatable around axis A.

[0058] The mixing device 2 is advantageously configured to continuously stir the contents of the reaction chamber 8, which include, for example, fiber waste ST and solvolysis mixture MS, both along axis A and radially relative to axis A (through its rotational motion about axis A) by dynamically distributing the contents into its interior.

[0059] Preferably, the mixing device 2 includes a plurality of paddles 11, which may be of various shapes, sizes, and arrangements.

[0060] In an advantageous embodiment, the paddle 11 is housed within the reaction chamber 8 and is securely associated with a support structure 12 that is rotatable around axis A.

[0061] For example, the support structure 12 may advantageously include a hollow cylindrical basket housed within the casing 5, having a radially outer surface facing the side wall 6 of the casing 5 and a radially inner surface from which the paddle 11 extends radially toward axis A.

[0062] Advantageously, the paddles 11 may have different shapes and sizes and may be arranged in various ways on the support structure 12.

[0063] However, it should be understood that the mixing apparatus 2 may be of a type other than those shown herein merely as examples, and may include paddles of various shapes and sizes arranged in various ways.

[0064] In one example of an advantageous embodiment of reactor 1 (not shown in the accompanying drawings), paddles 11 of various shapes, including ribbon-shaped paddles, can be advantageously separated from the support structure 12 located in the center of the reaction chamber 8 along axis A.

[0065] In other advantageous embodiments (not shown), the mixing device 2 may be integrated with the casing 5 and may rotate integrally with the casing 5 around axis A. In such advantageous embodiments, the casing 5 is rotatably mounted to an external support (not shown) and rotatably pulls the paddle 11.

[0066] The mixing device 2 is, for example, located outside the casing 5 and is advantageously driven by a motor 13 which is preferably connected to a support structure 12 (or directly to the casing 5 if the casing 5 is rotatable).

[0067] Advantageously, the thermal control system 3 is configured to extract or introduce thermal energy (heat) from the reaction chamber 8 within the casing 5, thereby cooling or heating the casing 5 and its contents.

[0068] Advantageously, the thermal control system 3 is suitable for transferring heat from a thermal unit (not shown) and comprises at least one coil 31 wound around the side wall 6 of the casing 5, in which a heat transfer fluid circulates, preferably the fluid being appropriately heated or cooled.

[0069] Advantageously, the microwave generation and transport system 4 comprises a microwave generator 41 preferably located outside the casing 5, and a guide device 42 associated with the microwave generator 41 and at least partially housed within the reaction chamber 8, and is advantageously configured to transport and distribute the microwaves generated by the microwave generator 41 within the reaction chamber 8 along and around axis A.

[0070] Advantageously, the guide device 42 includes a waveguide 43 (a so-called "leak pipe" type) which comprises a pipe extending along the axis A of the casing 5 between a pair of end walls 10, and which preferably has lateral discharge holes formed in the side walls of the pipe.

[0071] Advantageously, microwaves with a frequency of 300 MHz to 300 GHz are sent into the reaction chamber 8.

[0072] In a more advantageous embodiment of reactor 1 (such as schematically shown in Figure 9), reactor 1 also comprises a mixing device 2, a thermal control system 3, and a microwave generation and transport system 4.

[0073] Compared to the advantageous embodiment shown in Figure 8, the reactor 1 and casing 5 in the advantageous embodiment shown in Figure 9 extend along and around the longitudinal axis A, which is substantially vertical during use. Axis A is also the axis of rotation of the mixing apparatus 2.

[0074] Here again, the mixing device 2 is advantageously configured to continuously stir the contents of the reaction chamber 8 (e.g., fiber waste ST and solvolysis mixture MS) both along axis A and radially with respect to axis A through its rotational motion by dynamically distributing them into its interior.

[0075] Advantageously, the mixing device 3, which is advantageously driven by the motor 13, is configured such that the support structure 12, which includes at least one impeller 14 and at least one paddle 11, is not only rotatable about axis A but also axially movable along axis A.

[0076] Advantageously, the mixing device 2 can take on various configurations and may provide, for example, one or more paddles 11 of various shapes and organized forms, which may be placed on more impellers 14 in some cases.

[0077] Furthermore, in an example of an advantageous embodiment of reactor 1 shown in Figure 9, reactor 1 and its possible contents can be advantageously cooled or heated thanks to the thermal control system 3.

[0078] Advantageously, the thermal control system 3 may also include, in addition to or as a substitute for the coil 31, a further heating / cooling device (not shown in the accompanying drawings) that acts directly on the mixing device 2, for example, the paddle 11 and / or impeller 14, in either the advantageous embodiment shown in Figure 8 or the embodiment shown in Figure 9.

[0079] Advantageously, if a microwave generation and transport system 4 is provided, the microwaves necessary for the depolymerization reaction can be directly introduced into the reaction chamber 8 via a waveguide 42 or the like.

[0080] Advantageously, the method according to the present invention includes a mixing step 130 prior to the depolymerization step 110, in which possible reaction water AR, a water-soluble organic reaction solvent SOIR, and an alkali metal hydroxide IMA are mixed to form a solvolysis mixture MS.

[0081] Preferably, the method according to the present invention further comprises a shredding step 120 of fibrous waste ST prior to the depolymerization step 110, wherein the waste is shredded into small pieces.

[0082] Advantageously, reactor 1 is then supplied with the solvolysis mixture MS and preferably shredded fiber waste ST. The depolymerization reaction of the polyester component proceeds in reactor 1 until a two-phase mixture MB is obtained.

[0083] Advantageously, the depolymerization reaction is carried out at a temperature in the range of 90°C to 350°C, preferably 100°C to 200°C.

[0084] Advantageously, the depolymerization reaction takes place at pressures ranging from 1 atmosphere to 20 atmospheres.

[0085] The two-phase mixture MB comprises an initial solid phase FSI containing terephthalate SAT and cellulose fibers, such as cotton fibers, and an initial liquid phase FLI.

[0086] The initial liquid phase FLI contains a water-soluble organic reaction solvent SOIR, a possible residual fraction of reaction water AR, a possible soluble contaminant such as dyes, and / or a possible fraction of alkali metal hydroxide IMA that did not participate in the depolymerization reaction, and a possible soluble fraction of terephthalate SAT.

[0087] The undissolved fraction of terephthalate SAT arises as solid particles that can be freely suspended in the initial liquid phase FLI and / or trapped between cellulose fibers immersed in the initial liquid phase FLI.

[0088] The method according to the present invention includes a first solid-liquid separation step 210 following the depolymerization step 110, in which at least a portion of the initial liquid phase FLI is removed from the two-phase mixture MB. This removal is preferably carried out by mechanical filtration, for example, in a first solid-liquid separation unit USSL1 (schematically shown in Figure 3).

[0089] The solid-liquid separation unit USSL1 could be, for example, an industrial machine of the type commonly known as a screw filter.

[0090] Advantageously, the initial liquid phase FLI removed during the first step of solid-liquid separation 210 can be subjected to a filtration step using activated carbon 211 (Schematically shown in Figure 3) where any contaminants are removed, thus allowing the purified liquid phase FLP to be advantageously used in the subsequent distillation step 212. The reaction water AR and water-soluble organic reaction solvent SOIR contained in the purified liquid phase FLP are separated by distillation, and a purified liquid phase FLP can be obtained which may be reused later, for example, in a depolymerization step 110 performed thereafter.

[0091] In a more advantageous embodiment (not shown), the initial liquid phase FLI removed during the first solid-liquid separation step 210 may be used in the subsequent depolymerization step 210 either directly or in the form of a purified liquid phase FLP (after potentially being filtered by activated carbon 211), without being subjected to the distillation step 212.

[0092] While much of the initial liquid phase FLI of the two-phase mixture MB is removed during the first step 210 of solid-liquid separation, it should be emphasized that the initial solid phase FSI emerging from the first step 210 of solid-liquid separation may contain a residual fraction of the initial liquid phase FLI, which may include one or more contaminants dissolved within it (e.g., those trapped between cellulose fibers).

[0093] Therefore, the method according to the present invention comprises a step 220 of treatment with an organic solvent following the first step 210 of solid-liquid separation, wherein the possible residual fraction of the initial solid phase FSI containing cellulose fibers (e.g., cotton), terephthalate SAT, and the initial liquid phase FLI containing one or more contaminants dissolved therein is treated with an organic washing solvent SOL to remove one or more contaminants that may be present therein.

[0094] Advantageously, the organic cleaning solvent SOL is Glycols C2-C8, Alcohols C1-C6 or mixtures of alcohols C1-C6, Ketones C3-C8 or a mixture of ketones C3-C8 Ether or a mixture of ether, Alkanes C5-C8 or mixtures of alkanes C5-C8 It is at least one of the substances, or contains at least one of them.

[0095] Preferably, the glycol is a glycol having a boiling point of less than 300°C.

[0096] Preferably, the glycol is selected from monoethylene glycol (MEG), diethylene glycol (DEG), triethylene glycol (TEG), and mixtures thereof, and more preferably, the glycol is monoethylene glycol (MEG).

[0097] Preferably, alcohols C1 to C6 are selected from methanol (MeOH), ethanol (EtOH), isopropanol (i-PrOH), butanol (BuOH), and mixtures thereof.

[0098] Preferably, ketones C3-C8 are selected from acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and mixtures thereof.

[0099] Preferably, the ether is selected from diethyl ether (Et2O), tetrahydrofuran (THF), and mixtures thereof.

[0100] Preferably, the alkanes C5-C8 are selected from hexane, heptane, octane, and mixtures thereof.

[0101] Preferably, the water-soluble organic reaction solvent SOIR and the organic washing solvent SOL are the same substance or a mixture of the same substance.

[0102] At the end of the organic solvent treatment step 220, a purified solid-phase FSP is obtained, which likely still contains terephthalate SAT and cellulose fibers, such as cotton fibers, which are still immersed in a predetermined amount of organic washing solvent SOL, and in which contaminants may be dissolved.

[0103] Advantageously, the method according to the present invention comprises a second solid-liquid separation step 230 following the organic solvent treatment step 220, in which the purified solid-phase FSP is separated from any organic washing solvent SOL that may still be present and one or more possible contaminants dissolved therein.

[0104] Such separation is preferably carried out by evaporation, advantageously within a second solid-liquid separation unit USSL2 (Schematically shown in Figure 5). Evaporation is preferably carried out at a pressure lower than atmospheric pressure.

[0105] Advantageously, the organic washing solvent SOL used in the organic solvent treatment step 220 may include a portion of the new organic washing solvent SOLF and a portion of the recovered organic washing solvent SOLR obtained by separating it from the purified solid phase FSP in a second step 230 of solid-liquid separation, which is preferably carried out prior to the organic solvent treatment step 220 by evaporation and subsequent condensation.

[0106] Advantageously, step 220, which involves treatment with an organic solvent, may include one or more substeps of a solid solvent mixture 221, in which the initial solid phase FSI is added to and mixed with the organic washing solvent SOL, following the first step 210 of solid-liquid separation. It is preferable that one or more such substeps of the solid solvent mixture 221 are carried out in one or more solvent mixing units UMS.

[0107] The solvent mixing unit (UMS) is preferably an industrial machine of the type commonly known as a ribbon mixer.

[0108] Advantageously, the organic washing solvent SOL used in one or more substeps of the solid solvent mixture 221 comprises at least a portion of the water-soluble organic reaction solvent SOIR, which is distilled in a potentially pre-distillation step 212.

[0109] Preferably, each of these one or more substeps 221 of solid solvent mixing is followed by each substep 222 of solid solvent separation, and the organic washing solvent SOL subjected to the substep 221 of solid solvent mixing is preferably at least partially removed from the initial solid phase FSI by mechanical filtration in one or more solvent separation units USS.

[0110] The solvent separation unit (USS) is preferably an industrial machine of the type commonly known as a screw filter.

[0111] Advantageously, as better described below, one or more substeps of the solid solvent mixture 221 comprise two or more substeps of the solid solvent mixture 221. Preferably, the purity of the organic washing solvent SOL used in the two or more substeps of the solid solvent mixture 221 increases from the beginning to the end of the two or more substeps.

[0112] The organic washing solvent SOL used at the end of one or more substeps 221 of the solid solvent mixing preferably comprises a portion of the new organic washing solvent SOLF and a portion of the recovered organic washing solvent SOLR obtained by removing from the purified solid phase FSP in a second step 230 of solid-liquid separation, preferably by evaporation and subsequent condensation, which is performed before the end of one or more substeps of the solid solvent mixing 221.

[0113] Figure 4 schematically shows an example of the organic solvent treatment step 220 in an advantageous embodiment of the method according to the present invention.

[0114] In such advantageous embodiments, the organic solvent treatment step 220 comprises three substeps 221 of solid solvent mixing, each followed by a substep 222 of solid solvent separation in series with respect to each other.

[0115] In the first substep 2211 of solid-solvent mixing, which is advantageously performed within the first solvent mixing unit UMS1, the initial solid-phase FSI is added to and mixed with the organic washing solvent for the first time. This solvent is referred to herein as the first washing organic solvent SOL1.

[0116] Advantageously, after the first substep 2211 of solid solvent mixing, the first washing organic solvent SOL1 is at least partially removed from the initial solid phase FSI in the first substep 2221 of solid solvent separation, which is advantageously performed in the first solvent separation unit USS1.

[0117] Advantageously, the first washing organic solvent SOL1 removed during the first substep of solid solvent separation 2221 can be at least partially reused, for example, in a subsequent depolymerization step 110, preferably after filtration with activated carbon, to incorporate the water-soluble organic reaction solvent SOIR in the solvolysis mixture MS used in such a depolymerization reaction.

[0118] Following the first substep 2221 of solid solvent separation, in a second substep 2212 of solid solvent mixing, which is favorably performed in the second solvent mixing unit UMS2, the initial solid phase FSI is added to the organic washing solvent and mixed again. This solvent is referred to herein as the organic solvent of the second washing SOL2.

[0119] Advantageously, after the second substep 2212 of solid solvent mixing, the organic solvent of the second washing SOL2 is at least partially removed from the initial solid phase FSI in the second substep 2222 of solid solvent separation, which is advantageously carried out in the first solvent separation unit USS2.

[0120] Advantageously, the organic solvent of the second washing SOL2 separated from the initial solid phase FSI in the second solvent separation unit USS2 can be at least partially reused as the solvent for the first washing SOL1 in a further first substep 2211 of the subsequent solid solvent mixing.

[0121] Following the second substep 2222 of solid solvent separation, in a third substep 2213 of solid solvent mixing, which is advantageously performed in a third solvent mixing unit UMS3, the initial solid phase FSI is added to and mixed with an organic solvent of the third washing SOL3, which preferably contains a fresh organic washing solvent SOLF.

[0122] Advantageously, the organic solvent of the third washing SOL3 may include a recovered organic washing solvent SOLR obtained by separating it from the purified solid phase FSP, preferably by evaporation and subsequent condensation, which is performed in the second step of solid-liquid separation 230, prior to the third substep 2213 of solid solvent mixing.

[0123] Advantageously, after the third substep 2213 of solid solvent mixing, the organic solvent of the third washing SOL3 is at least partially removed from the initial solid phase FSI in the third substep 2223 of solid solvent separation, which is carried out in the third solvent separation unit USS3, thus obtaining a purified solid phase FSP, which is optionally immersed in the third washing organic solvent SOL3.

[0124] Advantageously, the third washing organic solvent SOL3 separated from the initial solid phase FSI in the third solvent separation unit USS3 can be at least partially reused as the second washing solvent SOL2 in a further second substep 2212 of the subsequent solid solvent mixing.

[0125] In other words, in this advantageous embodiment, the organic washing solvent SOL is reused several times in substeps of solid solvent mixing that are performed at different times, with its purity gradually decreasing. Thus, a particular substep of solid solvent mixing is performed using an organic washing solvent that is purer than the one used in the substep preceding the solid solvent mixing.

[0126] The method according to the present invention includes a step 240 of treatment with water following a second step 230 of solid-liquid separation, during which the purified solid phase FSF is brought into contact with washing water AL to solubilize and remove any present terephthalic acid SAT, thereby obtaining a final solid phase FSF containing cellulose fibers, such as cotton fibers, which are possibly still immersed in a minimal amount of washing water AL.

[0127] Because terephthalate SAT has good solubility in water, it can be solubilized in washing water AL, and when the terephthalate SAT is a sodium-based salt such as sodium terephthalate Na2TA, it corresponds to, for example, approximately 13% by weight. Such solubilization makes it possible to remove solid particles of terephthalate SAT that may be trapped between cellulose fibers.

[0128] Advantageously, during the water treatment step 240, the wash water AL is at least partially removed from the purified solid phase FSP. This removed wash water AL, shown as SA-SAT in Figure 1, is actually an aqueous solution containing terephthalate SAT solubilized in water, and may be subjected to one or more further filtration steps (e.g., mechanical filtration and / or filtration with activated carbon) (not shown) to remove any contaminants that may still be present, and then advantageously subjected to a possible step of precipitation of terephthalic acid 310, to which an inorganic acid, e.g., hydrochloric acid HCl or H2SO4 sulfuric acid, is added. In this way, a suspension of initial terephthalic acid ATI (solid) is obtained in an aqueous acidic solution SAA of the respective salts of the acid and base (e.g., NaCl) used in the depolymerization reaction.

[0129] Advantageously, the method according to the present invention comprises a third solid-liquid separation step 250, following the step 240 of treatment with water, which separates the final solid-phase FSF from the wash water AL and one or more contaminants that may be dissolved therein, preferably by evaporation, and more preferably in a third solid-liquid separation unit USSL3 (schematically shown in Figure 7).

[0130] Evaporation is preferably carried out at a pressure below atmospheric pressure.

[0131] At the end of the third solid-liquid separation step 250, the cellulose components separated from the polyester and potential contaminants in the textile waste ST, such as cotton fibers, can be used, for example, to manufacture new fabrics.

[0132] Advantageously, the wash water AL used in the water treatment step 240 may include a portion of the new wash water ALF and a portion of the recovered wash water ALR that was previously carried out from the final solid phase FSF in the water removal step 250 of the textile waste recycling method according to the present invention.

[0133] Advantageously, step 240, which involves treatment with water, may include one or more substeps of the solid-water mixing step 241, in which the purified solid phase FSP is added to and mixed with the washing water AL. Preferably, one or more such substeps of the solid-water mixing step 241 are carried out in one or more water mixing units UMA.

[0134] The water mixing unit (UMA) is preferably an industrial machine of the type commonly known as a ribbon mixer.

[0135] Advantageously, the washing water AL used in one or more substeps of the solid-water mixing step 241 may include at least a portion of the reaction water AR distilled in the previously performed distillation step 212.

[0136] Each of the one or more substeps 241 of solid-water mixing is preferably followed by a substep 242 of solid-water separation, in which the washing water AL is at least partially removed from the purified solid phase FSP, preferably by mechanical filtration in one or more water separation units USA.

[0137] The water separation unit USA is preferably an industrial machine of the type commonly known as a screw filter.

[0138] Advantageously, one or more substeps of the solid-water mixture 241 include two or more substeps of the solid-water mixture 241, and the purity of the washing water AL used in one or more steps increases from the beginning to the end of such one or more substeps 241 of the solid-water mixture, as will be described in more detail below.

[0139] Advantageously, the water used at the end of one or more substeps of the solid-water mixing step 241 may include a portion of the new wash water ALF and a portion of the recovered wash water ALR removed from the final solid-phase FSF in a water removal step 250 of the textile waste recycling method according to the present invention, which is performed prior to the end of one or more substeps 241 of the solid-water mixing, preferably by evaporation and subsequent condensation of the residual wash water AL.

[0140] Figure 6 schematically shows an example of a water treatment step 240 in an advantageous embodiment of the method according to the present invention.

[0141] In this advantageous embodiment, the water treatment step 240 includes three substeps 241 of solid-water mixing, each followed by a substep 242 of solid-water separation in series with respect to one another.

[0142] The first substep 2411 of solid-water mixing is favorably carried out in the first water mixing unit UMA1, where the purified solid phase FSP is first added to and mixed with the wash water. Hereinafter, this water is referred to as the first wash water AL1.

[0143] Advantageously, after the first substep 2411 of solid-water mixing, in the first substep 2421 of solid-water separation, the first wash water AL1 is at least partially removed from the purified solid phase FSP, advantageously carried out in the first water separation unit USA1. The first wash water AL1 thus removed (shown as SA~SAT in Figure 6) is, in fact, an aqueous solution containing solubilized terephthalate.

[0144] Following the first substep 2421 of solid-water separation, in a second substep 2412 of solid-water mixing, which is advantageously performed in a second water mixing unit UMA2, the purified solid phase FSP is added to the wash water and mixed again. Such water is referred to herein as the second wash water. Such water is referred herein as the second wash water AL2.

[0145] Advantageously, after the second substep 2412 of solid-water mixing, in a second substep 2422 of solid-water separation, which is advantageously performed in the second water separation unit USA2, the second wash water AL2 is at least partially removed from the purified solid phase FSP.

[0146] Advantageously, the second wash water AL2 separated from the purified solid phase FSP in the second water separation unit USA2 can be at least partially reused as the first wash water AL1 in an additional first substep of the solid-water mixing 2411 that is subsequently performed.

[0147] In the third substep 2413 of solid-water mixing, following the second substep 2422 of solid-water separation, the purified solid phase FSP is added to and mixed with the third wash water AL3, which preferably contains fresh wash water ALF.

[0148] Advantageously, the third wash water AL3 may include the recovered wash water ALR removed from the final solid phase FSF in a moisture removal step 250 of the textile waste recycling method according to the present invention, which has been carried out in advance.

[0149] Advantageously, after the third substep 2413 of solid-water mixing, in a third substep 2423 of solid-water separation, which is advantageously performed in the third water separation unit USA3, the third wash water AL3 is at least partially removed from the purified solid phase FSP to obtain the final solid phase FSF, which is optionally immersed in the third residual wash water AL3.

[0150] Advantageously, the third wash water AL3 separated from the purified solid phase FSP in the third water separation unit USA3 can be at least partially reused as the second wash water AL2 in a further second substep 2412 of solid-water mixing that is subsequently performed.

[0151] In other words, in this advantageous embodiment, the wash water AL is reused several times at progressively lower purity levels in substeps of solid-water mixing performed at different times. Thus, a particular substep of solid-water mixing is performed using wash water that is purer than that used in the substep preceding the solid-water mixing.

[0152] As described above, the aqueous solution of terephthalate SA-SAT (shown in the advantageous embodiment shown in Figure 6 as the first washing water AL1 separated from the purified solid phase FSP in the first solid-water separation unit 2421) removed in the solid-water separation step 240 can be favorably used in the terephthalic acid precipitation step 310, where an inorganic acid, such as hydrochloric acid (HCl) or sulfuric acid (H2SO4), is added to obtain a suspension of the initial terephthalic acid ATI (solid) in an aqueous solution of the salt SAA for the acid used (for example, sodium chloride (NaCl) is used in the case of (HCl), or sodium sulfate (Na2SO4) is used in the case of sulfuric acid (H2SO4), for example) and a suspension of the base used in the depolymerization reaction (for example, alkali metal hydroxide IMA such as sodium hydroxide (NaOH) and / or potassium hydroxide (KOH) and / or lithium hydroxide (LiOH)).

[0153] Furthermore, in the precipitation step of terephthalic acid 310, the suspended initial terephthalic acid ATI is separated from the acidic aqueous solution SAA by precipitation.

[0154] Advantageously, after the precipitation step of terephthalic acid 310, in the separation step of terephthalic acid 320, the acidic aqueous solution SAA is at least partially removed from the precipitated initial terephthalic acid ATI, preferably by mechanical filtration, for example, centrifugation.

[0155] Preferably, after the step of separating terephthalic acid 320, the initial terephthalic acid ATI, which is still wet, possibly with some of the acidic aqueous solution SAA, is subjected to a washing step for terephthalic acid 330, where it is brought into contact with water, preferably fresh water, to remove any residual inorganic acids that may remain from the steps prior to the precipitation of terephthalic acid 310 and the separation of terephthalic acid 320, thereby obtaining purified terephthalic acid ATP.

[0156] Preferably, after the step of washing terephthalic acid 330, the purified terephthalic acid ATP is subjected to the step of drying terephthalic acid 340, and the water used in the step of washing terephthalic acid 330 with water is removed from the purified terephthalic acid ATP, preferably by evaporation, thus obtaining the final terephthalic acid ATF.

[0157] The purity of the final terephthalic acid ATF obtained in this way is high enough to be used in new polymerization reactions, such as in the production of PET.

[0158] Advantageously, a crystallization step 331 of terephthalic acid can be provided between the step 330 of washing the terephthalic acid and the step 340 of drying the terephthalic acid, thereby crystallizing the terephthalic acid.

[0159] Advantageously, the aqueous acid solution SAA separated from the initial terephthalic acid ATI during the terephthalic acid separation step 320 may be subjected to a neutralization step 350, where it is placed in contact with one or more alkaline bases, such as an alkali metal hydroxide IMA, such as sodium hydroxide (NaOH) and / or potassium hydroxide (KOH) and / or lithium hydroxide (LiOH).

[0160] Such reactions between one or more alkali bases and inorganic acids, for example, hydrochloric acid (HCl) or sulfuric acid (H2SO4), may still be present in the acidic aqueous solution SAA, leading to the formation of alkali metal salts (e.g., sodium chloride (NaCl) and / or potassium chloride (KCl) and / or lithium chloride (LiCl) if hydrochloric acid (HCl) is used in the precipitation step of terephthalic acid 310, or sodium sulfate (Na2SO4) if sulfuric acid (H2SO4) is used), resulting in the neutralization of the pH of the acidic aqueous solution SAA, yielding a neutral aqueous solution SAN with a pH substantially equal to 7.

[0161] Advantageously, such a neutral aqueous solution SAN containing an alkali metal salt (e.g., sodium chloride (NaCl) and / or potassium chloride (KCl) and / or lithium chloride (LiCl) when hydrochloric acid (HCl) is used in step 310 of terephthalic acid precipitation, or sodium sulfate (Na2SO4) when sulfuric acid (H2SO4) is used) is subjected to a recovery step 380, which includes an electrolysis step 360 and a possible combination step 370 (which may or may not be included, depending on the particular embodiment), after a neutralization step 350. From this, the same inorganic acid (e.g., HCl or H2SO4) is obtained and used in step 310 of terephthalic acid precipitation of the method according to the present invention. The inorganic acid thus obtained can be advantageously used in a further step 310 of terephthalic acid precipitation that is carried out thereafter.

[0162] Advantageously, one or more alkali metal hydroxide IMAs, such as sodium hydroxide (NaOH) and / or potassium hydroxide (KOH) and / or lithium hydroxide (LiOH), are obtained from the recovery step 380. Advantageously, such one or more alkali metal hydroxide IMAs (e.g., sodium hydroxide (NaOH) and / or potassium hydroxide (KOH) and / or lithium hydroxide (LiOH)) may be at least partially reused in the depolymerization step 110 performed, preferably then mixed with any reaction water AR and water-soluble organic reaction solvent SOIR in a possible mixing step 130, and / or used at least partially in the neutralization step 350 performed thereafter.

[0163] For example, in the favorable first embodiment shown in Figure 1, the precipitation step 310 of terephthalic acid uses hydrochloric acid (HCl) as the inorganic acid, the recovery step 380 favorably includes a first step 361 of electrolysis, and the neutral aqueous solution SAN obtained by neutralization of the acidic aqueous solution SAA in the neutralization step 350 is subjected to an electrolysis process preferably carried out in a two-chamber cell. Gaseous chlorine (Cl2) and hydrogen (H2) are obtained from this process, which then react with each other in a first step 371 of a combination favorably provided in this recovery step 380, yielding hydrochloric acid (HCl) at the output.

[0164] In this first advantageous embodiment, one or more alkali metal hydroxide IMAs, such as sodium hydroxide (NaOH) and / or potassium hydroxide (KOH) and / or lithium hydroxide (LiOH), can also be advantageously obtained from the first step of electrolysis 361, which can be advantageously reused at least partially in the neutralization step 350 and / or depolymerization step 110 and / or possible mixing step 130, which are performed following the first step 361 of electrolysis.

[0165] For example, in the second advantageous embodiment shown in Figure 10, sulfuric acid (H2SO4) is used as the inorganic acid in the terephthalic acid precipitation step 310, and the recovery step 380 advantageously includes a second step 362 of electrolysis, where the neutral aqueous solution SAN obtained from the neutralization of the acidic aqueous solution SAA in the neutralization step 350 is subjected to an electrolysis process preferably carried out in a three-chamber cell. Gaseous oxygen (O2) and hydrogen (H2), sulfuric acid (H2SO4) and one or more alkali bases such as one or more alkali metal hydroxides IMA, for example, sodium hydroxide (NaOH) and / or potassium hydroxide (KOH) and / or lithium hydroxide (LiOH), are obtained from this process. Advantageously, gaseous oxygen (O2) and hydrogen (H2) react with each other in the second step 372 of the combination advantageously provided in the recovery step 380 to obtain water.

[0166] Advantageously, one or more alkali metal hydroxide IMAs, for example, sodium hydroxide (NaOH) and / or potassium hydroxide (KOH) and / or lithium hydroxide (LiOH) obtained in the second step of electrolysis 362, can be at least partially reused in the neutralization step 350 and / or depolymerization step 110 and / or possible mixing step 130 performed after the second electrolysis step 362.

[0167] Therefore, the present invention has proven to solve the above problems and objectives by enabling the recycling of textile waste containing cellulose components, such as cotton fibers and polyester components, by effectively separating them by chemical means using the method according to the present invention.

[0168] The method according to the present invention further comprises removing any contaminants such as coloring pigments from the cellulose and polyester components, and has the advantage of returning substantially pure and readily reusable monomer products of the cellulose and polyester components.

[0169] Furthermore, the method according to the present invention is suitable for industrial-scale embodiments and is relatively simple and inexpensive.

[0170] Another advantage of the method according to the present invention is sustainability. In fact, the auxiliary chemicals and water used in some steps of this method are suitable for recovery and reuse in other steps of the same method performed later, thus minimizing the need for replenishment of these substances and their release into the environment.

[0171] Finally, it is clear that the methods according to the present invention described herein are subject to numerous modifications or variations, all of which fall within the scope of the invention. Furthermore, all details can be replaced with technically equivalent elements without departing from the scope of the appended claims.

Claims

1. A method for recycling textile waste (ST) containing cellulose and polyester components, comprising the following steps: - A depolymerization step 110 comprising subjecting the fiber waste (ST) obtained by basic hydrolysis of the polyester component with a solvolysis mixture (MS) containing alkali metal hydroxide (IMA) and at least a water-soluble organic reaction solvent (SOIR) to a depolymerization reaction until a two-phase mixture (MB) is obtained, comprising an initial solid phase (FSI) containing terephthalate (SAT) and cellulose fibers and an initial liquid phase (FLI) containing the water-soluble organic reaction solvent (SOIR); - A first step 210 of solid-liquid separation, comprising removing at least a portion of the initial liquid phase (FLI) from the two-phase mixture (MB); - Following the first step 210 of solid-liquid separation, step 220 of treatment with an organic solvent is performed, wherein the initial solid phase (FSI) is treated with an organic washing solvent (SOL) until one or more contaminants that may be present in the initial solid phase (FSI) are removed to obtain a purified solid phase (FSP) containing the terephthalate (SAT) and the cellulose fibers; - A second step 230 of solid-liquid separation, in which the purified solid phase (FSP) is separated from the organic washing solvent (SOL) and the one or more possible contaminants dissolved therein; - A water treatment step 240 comprising: contacting the purified solid phase (FSP) with washing water (AL) until the terephthalate (SAT) contained therein is solubilized; and removing the terephthalate (SAT) to obtain a final solid phase (FSF) containing the cellulose fibers, A method for recycling textile waste (ST) containing cellulose and polyester components, characterized by including the following.

2. The aforementioned organic washing solvent (SOL) is the following substance: - Glycol C ２ ~C ８ , - Alcohol C １ ~C ６ or alcohol C １ ~C ６ A mixture of - Ketone C ３ ~C ８ or a mixture of ketone C ３ ~C ８ and - Ether or a mixture of ether, - Alkan C ５ ~C ８ or Alkane C ５ ~C ８ A mixture of The method according to claim 1, wherein at least one of the or including at least one of the.

3. The method according to claim 1 or 2, wherein the water-soluble organic reaction solvent (SOIR) and the organic washing solvent (SOL) are the same substance or a mixture of the same substance, or contain the same substance or a mixture of the same substance.

4. The method according to any one of claims 1 to 3, wherein the step 220 of treating with the organic solvent comprises one or more substeps 221 of solid solvent mixing in which the initial solid phase (FSI) is added to and mixed with the organic washing solvent (SOL), each of which is followed by a substep 222 of solid solvent separation in which the organic washing solvent (SOL) is removed at least partially from the initial solid phase (FSI).

5. The method according to claim 4, wherein one or more substeps 221 of the solid solvent mixture comprises two or more substeps 221 of the solid solvent mixture, and the purity of the organic washing solvent (SOL) used in the two or more substeps 221 of the solid solvent mixture increases from the beginning to the end of the two or more substeps 221 of the solid solvent mixture.

6. The method according to claim 4 or 5, wherein the organic washing solvent (SOL) used at the end of one or more substeps 221 of the solid solvent mixture comprises a portion of a new organic washing solvent (SOLF) and a portion of a recovered organic washing solvent (SOLR) obtained by removing it from a purified solid phase (FSP) in a second step 230 of solid-liquid separation of the method according to any one of claims 1 to 5, performed before the end of one or more substeps of the solid solvent mixture 221.

7. The method according to any one of claims 1 to 6, further comprising a water removal step (250) after the water treatment step 240, which includes removing any wash water (AL) that may be present therein from the final solid phase (FSF).

8. The method according to any one of claims 1 to 7, wherein the step 240 of treating with water comprises one or more substeps 241 of solid-water mixing in which the purified solid phase (FSP) is added to and mixed with washing water (AL), each of which is followed by a substep 242 of solid-water separation in which the washing water (AL) is at least partially removed from the purified solid phase (FSP).

9. The method according to claim 8, wherein one or more substeps 241 of the solid-water mixing comprises two or more substeps 241 of the solid-water mixing, and the purity (AL) of the washing water used in the two or more substeps 241 of the solid-water mixing increases from the beginning to the end of the two or more substeps 241 of the solid-water mixing.

10. The method according to claim 8 or 9 as dependent on claim 7, wherein the wash water (AL) used at the end of one or more substeps 241 of the solid-water mixing comprises a portion of new wash water (ALF) and a portion of recovered wash water (ALF) removed from the final solid phase (FSF) performed prior to the end of one or more substeps 241 of the solid-water mixing in the water removal step 250 of the textile waste (ST) recycling method according to claim 7 or a claim dependent on claim 7.

11. During step 240, which involves treatment with water, the washing water (AL) is at least partially removed from the purified solid phase (FSP), and the removed washing water (SA-SAT) is subjected to a terephthalic acid precipitation step 310, in which it reacts with an inorganic acid to form a suspension of initial terephthalic acid (ATI) in an aqueous acid solution (SAA). The method comprises a step 320 for separating the terephthalic acid, wherein the initial terephthalic acid (ATI) is removed from the acidic aqueous solution (SAA), and the acidic aqueous solution (SAA) is then subjected to a neutralization step 350 of the method, in which the acidic aqueous solution (SAA) is brought into contact with an alkali base to form an alkali metal salt and obtain a neutral aqueous solution (SAN). The method comprises subjecting the neutral aqueous solution (SAN) to a recovery step 380, which includes an electrolysis step 360 and, optionally, a combination step 370, from which the same inorganic acid used in the precipitation step 310 of terephthalic acid and the same alkaline base used in the neutralization step 350 are obtained, the inorganic acid thus obtained being used in a further step 310 of the method according to any one of claims 1 to 10, which is subsequently carried out to precipitate the terephthalic acid according to the method according to any one of claims 1 to 10.

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