Process for separating and recovering fibres of blended textiles

Abstract

Process for separating and recovering fibres of blended textiles, comprising: providing (100) a blended textile comprising at least a first fibre type being cellulosic fibres and at least a second fibre type being non-cellulosic fibres, dissolving (101) a polar ionic liquid in a supercritical or subcritical phase, contacting (102) the blended textile with the supercritical or subcritical phase, allowing the supercritical or subcritical phase to diffuse into the blended textile, thereby solvating the cellulosic fibres in the supercritical or subcritical phase, depressurizing (103) the supercritical or subcritical phase, collecting cellulosic fibres (104) solvated by the supercritical or subcritical phase, and collecting non-dissolved non-cellulosic fibres (105).

Description

[0001] PROCESS FOR SEPARATING AND RECOVERING FIBRES OF BLENDED TEXTILES

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a process for separating and recovering fibres of blended textiles, wherein the blended textile comprises cellulosic fibres and non- cellulosic fibres.

[0004] BACKGROUND ART

[0005] Today, less than 1 % of textile wastes are fibre to fibre recycled. Although there is a wide variety of technologies developed for recycling textiles based on mechanical, thermomechanical, thermochemical, chemical and biochemical processes, a major challenge is the recycling of fabric blends with multi-material fibre compositions. Moreover, the intimate entanglement between the different fibres in mixed fabrics results in lower separation efficiency due to reduced surface area exposed to the chemicals used in the recycling process. Among the fabric blends available in the market, blend of polyester and cotton (also known as polycotton) is one of the most prominent blends in the market. As such, large volumes of these difficult-to-recycle polycotton wastes are burned or landfilled every year. Therefore, addressing technological gaps in the recycling of polycotton and other complex blended textile wastes is crucial for the human health and the planet.

[0006] The companies Worn Again Technologies and Circ Technology target mixed fibres, such as polycotton, using specific chemicals and high temperatures in a hydrothermal reaction for the fibre separation. The fibres become fully dissolved in the process and need to be regenerated afterwards, which is energy and water intensive. The process used may further negatively impact the quality of the produced fibres.

[0007] CN1 15747991 A shows a method for recycling cellulose from a mixed textile comprising cellulose and polyester. The textile waste is crushed and the polyester is depolymerized to low molecular weight during a pre-treatment step. A supercritical fluid solubilized with an organic solvent is used to dissolve the cellulose. CN1 16625872A shows a method for separating components of cotton-polyester blended textiles by mixing the blended textiles in a mixed solvent of an ionic liquid and an organic solvent until the cellulose in the cotton-polyester blended textile is completely dissolved, thereby obtaining a mixture containing cellulose and polyester fabric.

[0008] CN107629245 shows a recycling method for waste polyester-cotton blended fabrics under hydrothermal conditions. The hydrolysis reaction takes place in aqueous sulfuric acid solution. The reaction product is separated by filtration to obtain polyester fibres and cellulose powder, and a hydrolyzate containing oligosaccharides.

[0009] There is, hence, a need for techniques for recycling of blended waste textiles, with low water and chemical consumption, little or no depolymerization of fibres and good quality of the separated fibres.

[0010] SUMMARY OF THE INVENTION

[0011] It is an object of the present invention to provide a process for recycling of blended textiles, with low water and chemical consumption, little or no depolymerization of fibres and good quality of the separated fibres.

[0012] The invention is defined by the appended independent patent claims. Non-limiting embodiments emerge from the dependent claims, the appended drawings, and the following description.

[0013] According to a first aspect there is provided a process for separating and recovering fibres of blended textiles, comprising: providing a blended textile comprising at least a first fibre type being cellulosic fibres and at least a second fibre type being non- cellulosic fibres; dissolving a polar ionic liquid in a supercritical or subcritical phase; contacting the blended textile with the supercritical or subcritical phase, allowing the supercritical or subcritical phase to diffuse into the blended textile, thereby solvating the cellulosic fibres in the supercritical or subcritical phase; depressurizing the supercritical or subcritical phase; collecting solvated cellulosic fibres in the supercritical or subcritical phase, and collecting non-dissolved non-cellulosic fibres.

[0014] With this process, the cellulosic and non-cellulosic fibres of the blended textile can be separated without the fibres being depolymerised or degraded. The supercritical or subcritical phase with ionic solvent has affinity mainly to the cellulosic fibres. That the ionic liquid (polar) is "dissolved" in the supercritical or subcritical phase means that the ionic liquid is mixed with the supercritical or subcritical phase to form a homogeneous solution. The supercritical or subcritical phase may further comprise other components such as a co-solvent. The ionic liquid molecules are evenly distributed / completely mixed within the supercritical / subcritical phase, resulting in a single, uniform and homogenous phase without any separation. Thereby, forming one supercritical / subcritical polar phase. The density and viscosity of the supercritical or subcritical phase (i.e. the combination of pressure and temperature of the supercritical or subcritical phase), the ionic liquid and amount thereof can be varied such that one supercritical / subcritical polar phase is obtained.

[0015] Initially the ionic liquid and the supercritical / subcritical carbon dioxide do not have any affinity for each other. The formed supercritical / subcritical phase can be made as polar as the cellulose, such that it can fully disrupt hydrogen bonds but still have the capacity to penetrate the blended textile (which is non-polar) such that the cotton can be fully extracted.

[0016] The supercritical or subcritical phase diffuses into the blend of material containing cellulosic and non-cellulosic material to disrupt hydrogen bonds in the cellulosic fibres and thereby “dissolve” only / mainly the cellulosic material. The cellulosic and the non- cellulosic material is then recovered / collected. This supercritical / subcritical phase disrupts the hydrogen bonding of the cellulose polymers without the polymers undergoing chemical change or depolymerization. The cellulosic fibres are not broken down, but maintained in polymeric form with preserved cellulose properties. This disruption of hydrogen bonding is a key step in allowing the cellulose chains to separate from each other and become solvated in the supercritical / subcritical phase.

[0017] The solvation of cellulose is a physical process where cellulose is dispersed in a solvent (supercritical or subcritical phase) without depolymerization. Depolymerization, on the other hand, involves the breaking of chemical bonds within the polymer chains leading to a reduction in the average molecular weight of the polymer and a potential deterioration of the properties of the monomers. The depolymerisation is a chemical process that results in a cleavage of polymer chains into small fragment. Depolymerisation (such as hydrothermal reaction), reduces the polymer chain length of polyester, which translate into weaker mechanical properties. Depolymerisation of cotton (cellulose) degrades the cotton into low molecular weight cellulose or glucose, thereby losing fibre strength. Thereby, such depolymerised fibres can mainly be used for lower grade applications. Moreover, impurities may affect the reuse quality and the next depolymerisation. In addition depolymerisation I repolymerization are highly energy intensive processes. The process described above does not imply depolymerization but rather the physical solvation of intact cellulose polymer chains in the supercritical / subcritical phase. The supercritical or subcritical phase diffuses within the blend of cellulose and non-cellulosic material and have the possibility to interact only with the cellulose polymers and dissolve it.

[0018] As cellulosic and non-cellulosic materials have different properties, it is not obvious to have a supercritical / subcritical phase that penetrates both materials and dissolve only one.

[0019] The solvation of cellulose into the supercritical phase or subcritical phase / the disruption of hydrogen bonds in in the cellulose / the solvation of cellulose is preferably at least 20 wt.%, and more preferably 80- to 100 wt.% dissolution. By using a weight loss method, the amount of the solvated cellulose can be quantified. The starting material is the blended textile material, and the method starts by defining the average wt.% of non- cellulosic fibres and cellulosic fibres in the blend. That can be done through thermogravimetry analysis (TGA), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and / or mechanical testing. Once the ratio of the cellulosic and non-cellulosic fibres is defined, the above-defined separation process is started and the separated fibres recovered. Both types of recovered fibres are weighed and then TGA analysis, SEM and / or FTIR is performed. Cellulosic and non-cellulosic fibres have different melting points and different decomposition temperature. Also, by using FTIR specific functional groups proper to cellulose and non-cellulose fibres can be identified.

[0020] Separating the blended fibres by depolymerizing one or more of the fibres requires specific chemicals that impact the properties of the components and much energy, as you need to break down the fibre structure to monomers and then repolymerize and regenerate the fibres. Further, the quality of such repolymerized and regenerated fibres is not as good as for intact fibres.

[0021] As compared to for example CN115747991 A, the above-described process does not require a depolymerization of the non-cellulosic fibres, such as polyester, nor to crush the blended textile material, since the aim of the process is to preserve the length and properties of the separated fibres of the blended material. The aim of the process described in CN115747991 A is to recover mainly the cellulose, not separation of cellulosic and non-cellulosic fibres without their depolymerization or degradation. In this document a first pretreatment step to depolymerize the polyester fibres is needed prior to cellulose solvation.

[0022] The above-described process, on the other hand, keep the full length of the fibres, thereby preserving the properties and the polymeric structure of both cellulosic and non-cellulosic fibres. Moreover, the above-described process can be used for any blended material comprising any cellulosic and any non-cellulosic fibres and is not only useful for polycotton. The process is energy efficient as both cellulosic and non- cellulosic fibres are recovered. Further, both fibre types are kept at as polymers and therefore there is no need for repolymerization and new waste streams.

[0023] The blended textiles can be waste textiles and the process used for recycling of such textiles. The process uses no water or a minimal amount of water as compared to traditional mechanical, thermomechanical, thermochemical, chemical or biochemical processes.

[0024] The process could be a batch, continuous or semi-continuous mode process. The blended textile, the polar ionic liquid dissolved in the supercritical or subcritical phase and / or the collection of solvated cellulosic fibres and / or non-cellulosic fibres could be provided or made in batch, continuous or semi-continuous mode.

[0025] The process is easily scalable. The process is energy efficient and uses green solvents such as supercritical / subcritical fluids, e.g. carbon dioxide, and substances, which may be recycled and reused continuously.

[0026] The cellulosic fibres of the blended textile may be natural or man-made cellulosic fibres selected from cotton, hemp, linen, ramie, modal, lyocell, bamboo, sisal, viscose, abaca, kenaf, jute or combinations thereof.

[0027] The non-cellulosic fibres of the blended textile may be selected from polyester, wool, nylon, elastane, silk, acrylic, polypropylene, polyethylene, polyamide, modacrylic, carbon fibre, aramid, novoloid, or combinations thereof.

[0028] The supercritical or subcritical phase may comprise a co-solvent. The blended textile contacted with the supercritical or subcritical phase may be in pieces of 1 cm2or larger.

[0029] The supercritical or subcritical phase may comprise supercritical or subcritical carbon dioxide, water, methane, ethane or propane.

[0030] At which pressures and temperatures such fluids are considered supercritical or subcritical is well-known in the art.

[0031] The ionic liquid may be selected from imidazolium-based ionic liquids, phosphonium- based ionic liquids, pyridinium-based ionic liquids, ammonium-based ionic liquids or combinations thereof.

[0032] The amount of ionic liquid dissolved in the supercritical or subcritical phase may be 0.05-60 mol%.

[0033] The co-solvent may be a polar co-solvent selected from ethanol, methanol, acetone, dimethyl sulfoxide, ethyl acetate, propylene carbonate, acetic acid, formic acid, water or any combination thereof.

[0034] The amount of co-solvent in the supercritical / subcritical phase may be 0.1-40 mol%.

[0035] An enzyme may be dissolved in the supercritical or subcritical phase.

[0036] The enzyme may be an enzyme selected from cellulases, endoglucanases, exoglucanases, / 3-glucosidases or combinations thereof.

[0037] The amount of enzyme dissolved in the supercritical or subcritical phase may be 5 to 30 g per 100 g of cellulose in the blended textile.

[0038] The supercritical or subcritical phase may further comprise N-Methylmorpholine N- oxide, dimethyl sulfoxide (DMSO), dimethyllacethamide (DMAc), and / or lithium chloide (LiCI).

[0039] The supercritical or subcritical phase may be brought into contact with the blended textile for at least 20 minutes.

[0040] The supercritical or subcritical phase and the blended textile may be present in a mass ratio between 0.5:1 to 50:1. The process may further comprise a step of removing colour and / or additive from the resulting solvated cellulosic fibres and / or non-cellulosic fibres.

[0041] The process may comprise a pre-step of extracting any moisture, dirt, grease or sizing agent from the blended textile material and / or to remove colour and / or additive from the blended textile before the blended textile is brought into contact with the supercritical / subcritical phase.

[0042] The blended textile may be dried in supercritical or subcritical carbon dioxide before being contacted with the ionic supercritical or subcritical phase.

[0043] Alternatively, the blended textile may be dried in an oven or by using any other conventional drying system.

[0044] In the process described above, the blended textile may be provided in a vessel divided into a first and second compartment by a perforated support, wherein the blended textile is provided on the support in the first compartment and an ionic liquid or an ionic liquid and polar co-solvent is provided in the second compartment, wherein a supercritical or subcritical phase is entered into or formed in the vessel, allowing the ionic liquid to dissolve in the supercritical or subcritical phase in the second compartment, wherein the blended textile in the first compartment is contacted with the supercritical or subcritical phase, thereby solvating the cellulosic fibres in the supercritical or subcritical phase, and after depressurizing the supercritical or subcritical phase, collecting the solvated cellulosic fibres in / from the second compartment, and collecting non-dissolved non-cellulosic fibres in / from the first compartment.

[0045] In the process described above, the blended textile may be provided in a first vessel, and a polar ionic liquid or polar ionic liquid and co-solvent provided in a second vessel, a supercritical or subcritical phase entered into or formed in the second vessel, allowing the ionic liquid to dissolve in the supercritical or subcritical phase, the supercritical or subcritical phase transferred from the second vessel to the first vessel, contacting the blended textile in the first vessel with the supercritical or subcritical phase, thereby solvating the cellulosic fibres in the supercritical or subcritical phase, after depressurizing the supercritical or subcritical phase, removing the depressurized supercritical or subcritical phase with solvated cellulosic fibres from the first vessel, and collecting the solvated cellulosic fibres.

[0046] BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Fig. 1 schematically illustrates a process for separating and recovering fibres of blended textiles.

[0048] Fig. 2 illustrates a system for performing an embodiment of the process shown in Fig. 1.

[0049] Fig. 3 illustrates an embodiment of the process in Fig. 1.

[0050] DETAILED DESCRIPTION

[0051] Below and in Figs 1 -3 is described in more detail a process for separating and recovering fibres of blended textiles, where the blended textile comprises cellulosic fibres and non-cellulosic fibres. The cellulosic fibres may be natural or man-made cellulosic fibres selected from cotton, hemp, linen, ramie, modal, lyocell, bamboo, sisal, viscose, abaca, kenaf, jute or combinations thereof. The non-cellulosic fibres may be polyester, wool, nylon, elastane, silk, acrylic, polypropylene, polyethylene, polyamide, modacrylic, carbon fibre, aramid, novoloid, or combinations thereof.

[0052] The textile blends to be recovered could for example be composed of cotton-polyester, polyester-cotton-rayon, polyester-spandex, wool-cotton, polyester viscose, cottonlinen, polyester-rayon, cotton-nylon and modal spandex. An example of textile blend is 65 wt.% polyester-35 wt.% cotton, 80 wt.% polyester-20 wt.% cotton, 50 wt.% polyester-50 wt.% cotton, 60 wt.%polyester-40 wt.% cotton, 70 wt.% polyester-30 wt.% cotton, 20 wt.% polyester-wt. 80% cotton.

[0053] In the first step 100, the blended textile is provided. A polar ionic liquid is dissolved in supercritical or subcritical phase 101 comprising e.g. supercritical or subcritical carbon dioxide, and the blended textile is contacted 102 with the supercritical or subcritical phase, e.g. for at least 20 minutes. Such a supercritical / subcritical phase penetrates both the cellulosic and non-cellulosic fibres, solvating the cellulose and leaving the non-cellulosic fibres intact. The supercritical or subcritical phase may comprise supercritical or subcritical carbon dioxide, water, methane, ethane or propane.

[0054] With supercritical fluid / phase (SCF) is meant a substance at a temperature and pressure above its critical point. At this critical point, distinct liquid and gas phases do not exist, but the substance remains in a single-phase state. SCFs exhibit properties between those of a gas and a liquid.

[0055] With subcritical fluid / phase is here meant a liquid at temperatures between the atmospheric boiling point and the critical temperature. It lies below the critical point, where distinct liquid and gas phases exist. Subcritical fluids can transition from a gas to a liquid without crossing the vapor-liquid boundary.

[0056] The supercritical or subcritical phase and the blended textile may be present in a mass ratio between 0.5: 1 to 50: 1 , or 5: 1 to 40: 1 , or preferably 10:1 to 30: 1 .

[0057] This ratio indicates that for every unit of weight of blended textile, a certain number of units of supercritical or subcritical fluid is needed to obtain fibre separation. The supercritical or subcritical fluid being used as the main solvent to solvate the cellulosic material in the textile blend. The ratios have been determined experimentally to define an optimal fibre separation.

[0058] The blended textile may be in pieces of 1 cm2or larger or 10 cm2or larger (with a thickness ranging from mm to cm). There is no need for shredding. If the textile is contacted with the supercritical / subcritical phase during mixing, large textile pieces, and full garments can be treated without any pre-cutting or shredding. The blended textile could, however, be shredded into smaller pieces before being contacted with the supercritical or subcritical phase to reduce the treatment time. Larger pieces of the blended textile may result in fibres with better properties. In one embodiment, the blended textile is first shredded or cut into smaller pieces, i.e. smaller than 10 cm2before being contacted with the supercritical or subcritical phase. Preferably, blended textile may be in pieces of at least 10 cm2or larger. This, as recovered fibres after the separation ideally should have a length of at least 1 cm, such as between 1 and 3 cm, or between 1 .2 and 2.8 cm. The blended textile could be textile waste from which any zips and buttons have been removed. The textile waste may include post-consumer and industrial waste garments, scrap fabric and / or various textile of biomass material as a raw feed material.

[0059] The polar ionic liquid dissolved in the supercritical or subcritical phase 101 , may be selected from imidazolium-based ionic liquids, phosphonium-based ionic liquids, pyridinium-based ionic liquids and ammonium-based ionic liquids. The amount of ionic liquid dissolved in the supercritical or subcritical phase may be 0.05-60 mol%, or 1 -50 mol%, or preferably 10-40 mol%.

[0060] Using 10-40 mol% of ionic liquid, a good solubility of ionic liquid in the supercritical / subcritical phase can be reached and also up to at least 85% dissolution / solvation of the cellulosic fibres in the supercritical / subcritical phase.

[0061] Examples of imidazolium-based ionic liquids: 1 -butyl-3-methylimidazolium acetate ([BMIM][OAc]), 1 -butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], and 1- ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]).

[0062] Examples of ammonium-based ionic liquids: tetrabutylammonium bromide ([N4444]Br).

[0063] Examples of phosphonium-based ionic liquids: Trihexyl(tetradecyl)phosphonium chloride ([P66614]CI), Triethylphosphonium acetate ([P222][OAc]), Trihexyl(tetradecyl)phosphonium acetate ([P66614][OAc]), Trihexyl(tetradecyl)phosphonium hydrogen sulfate ([P66614]HSO4), Tributylphosphonium chloride ([P4444]CI), Tributylphosphonium acetate ([P4444][OAc]), Trihexylphosphonium bromide ([P6666]Br)

[0064] Examples of pyridinium-based ionic liquids: 1-Butyl-4-methylpyridinium chloride ([BMPy][CI]), l -Butyl-3-methylpyridinium chloride ([BMP][CI]), 1 -Ethyl-3- methylpyridinium acetate ([EMPy][OAc]), 1 -Butyl-3-methylpyridinium acetate ([BMPy][OAc]).

[0065] Some ionic liquids may have a poor solubility in a supercritical / subcritical phase, why a polar co-solvent may be used to increase the solubility of the polar ionic liquid into the supercritical / subcritical phase. The co-solvent may be a polar co-solvent selected from ethanol, methanol, acetone, dimethyl sulfoxide, ethyl acetate, propylene carbonate, acetic acid, formic acid, water or any combination thereof, and the amount of co- solvent in the ionic supercritical / subcritical phase may be 0.1-40 mol%, or 5-30 mol%, or 10-20 mol%.

[0066] An enzyme may be dissolved in the supercritical or subcritical phase .The selected enzyme present an affinity towards cellulosic material. The enzyme may be an enzyme selected from cellulases, endoglucanases, exoglucanases, / 3-glucosidases or combinations thereof. The added enzyme may assist the supercritical or subcritical phase in penetrating into the blended textile and solvate the cellulosic material, while the non-cellulosic material remains intact. The amount of enzymes in the supercritical / subcritical phase may be 5 to 30 g Z100 g of cellulose to be solvated. The enzyme may first be dissolved in a smaller amount of a liquid, such as water, ethanol, methanol, water, DMSO, or acetone, to enhance the solubility of the enzyme in the supercritical / subcritical phase.

[0067] The supercritical or subcritical phase may further comprise N-Methylmorpholine N- oxide, dimethyl sulfoxide (DMSO), dimethyllacethamide (DMAc), and / or lithium chloide (LiCI) to obtain a supercritical or subcritical phase with a high affinity towards cellulose and therefore facilitate and accelerate its solvation and separation. NMMO is an organic compound that may be used as a solvent for cellulose.

[0068] The blended textile may be pretreated 100a in supercritical or subcritical fluid before being contacted with the ionic supercritical or subcritical phase. This step, which may last e.g. for 10 minutes to 60 minutes, is used in order to extract moisture and / or dirt from the blended textile before the textile is contacted with the supercritical or subcritical phase. A ratio of supercritical or subcritical fluid to blended textile in this step may be 0.5:1 to 50:1 , or 5:1 to 40:1 , or preferably 10:1 to 30:1 . Thereby, the efficiency of the following steps can be increased.

[0069] The process may in addition or alternatively comprise a pre-step 100b of removing colour and / or additive from the blended textile before the blended textile is brought into contact 102 with the supercritical / subcritical phase.

[0070] After the blended textile has been contacted 102 with the supercritical or subcritical phase, e.g. for at least 20 minutes, such that the supercritical / subcritical phase has penetrated both the cellulosic and non-cellulosic fibres, solvating the cellulose and leaving the non-cellulosic fibres intact. The supercritical or subcritical phase is then depressurized 103, solvated cellulosic fibres in the supercritical or subcritical phase collected 104 and non-dissolved non-cellulosic fibres collected 105.

[0071] The process may further comprise a step of removing colour and / or additive from the resulting solvated cellulosic fibres and / or non-cellulosic fibres 106, 107.

[0072] The solvated cellulose fibres in the ionic liquid could be wet spun in order to produce cellulose fibres, e.g. lyocell fibres. An anti-solvent could be used in case one want to exchange the ionic liquid with water and produce e.g. pulp sheet instead of wet spun fibres.

[0073] In Fig. 2 is illustrated an embodiment of the process in Fig. 1 and a detailed set-up for performing the process. The process / set-up may be used in batch, continuous or semi- continuous mode.

[0074] The blended textile 2 comprising the at least a first fibre type being cellulosic fibres and the at least a second fibre type being non-cellulosic fibres is provided 100 in a first vessel 5, which may be a first high-pressure autoclave 5. A second autoclave 3 is provided, which is connected to the first vessel 5 via a valve 60. The second autoclave 3 may be provided with or contain a determined volume / weight of polar ionic liquid and possibly also enzyme(s) 4.

[0075] A substance, here illustrated as CO2, from which supercritical or subcritical fluid is to be formed, is introduced into the second autoclave 3 and heated / pressurized until reaching a specific pressure and temperature to form the supercritical or subcritical phase. The ionic liquid is dissolved in the formed supercritical / subcritical phase.

[0076] CO2 from tank 6 goes through pipeline 24 to a cooler 11 , through a pipeline 25 to a pump 10, through pipeline 26 through flow sensor 17 to valve 30 and then to mixer 23.

[0077] A co-solvent in container 8 may be supplied through pipeline 28 to pump 9 and then through pipeline 29 to mixer 23 where it is mixed with the CO2. CO2 or CO2 mixed with co-solvent is supplied through pipeline 27 into the first vessel 3 until a certain pressure is reached. The first vessel 3 may also be heated to a certain temperature and a supercritical / subcritical phase is thus formed in the second vessel 3 in which the ionic liquid is dissolved. A semi-continuous flow of CO2 may be created in the first vessel 5 with CO2 directed from pipeline 26, through valve 31 via pipeline 32 to the first vessel 5. The semi- continuous flow CO2 leaves the first vessel 5 though pipeline 33, 34 via a CO2 filtration and recovery tank 7 and then back to pipeline 24. This semi-continuous CO2 flow may be used for extracting dirt, grease, and moisture from the blended textile 2. After a certain duration, valve 31 is closed in order to stop the CO2 introduction in the first vessel 5.

[0078] Valve 60 is opened in order to connect the second vessel 3 with the first vessel 5. The supercritical / subcritical phase from the second vessel 3 goes through pipeline 36 to the first vessel 5 and start diffusing the blended textile 2. The supercritical / subcritical phase containing ionic liquid will start penetrating the blended textile, swell it and then solvating the cellulosic part through breaking the cellulose's hydrogen bonds, the cellulose structure loses its integrity allowing therefore its solvation (without depolymerization).

[0079] At the end of the separation, valve 38 is opened and depressurization of the supercritical / subcritical phase is started. The CO2 is drawn with cellulose solvated in the ionic liquid through pipeline 34 and through a cyclone 37, where the cellulose solvated will be trapped and collected and the CO2 will continue through pipeline 39 to be recovered and filtered in tank 7 and then stored again in the tank 6. The non- solvateded separated non-cellulosic fibres remain intact in the first vessel 5.

[0080] Alternatively, at the end of the separation, the vessels 3, 5 are depressurized through re-connecting the two vessels 3, 5, wherein the ionic liquid, solvated cellulose and any co-solvent will be transferred / trapped in the second vessel 3. The polyester fibres will remain intact in the first reactor 5.

[0081] The separated and collected dissolved / solvated cellulose can be used in wet spinning or in pulp sheets production. The separated polyester fibres may be spun into new polyester yarns prior to carding and drawing processes.

[0082] In a specific example the second vessel / autoclave 3 is provided with 0.05 mol% of 1- butyl-3-methylimidazolium acetate ([BMIM][0Ac]) and 16 mol % of ethanol and the first vessel / autoclave 5 is provided with about 100 g of polycotton textile. The valve 60 between the two autoclaves 3, 5 is closed. CO2 is introduced in the second autoclave 3 to reach a pressure of 150 bar (15 MPa) and temperature of 70°C in a batch mode; the supercritical phase dissolves the [BMIM][0Ac],

[0083] CO2 is introduced in the first autoclave 5 containing the polycotton textile, the pressure is raised to 150 bar (15 MPa) and temperature to 70°C. A semicontinuous flow of CO2 while keeping the same pressure and temperature is used in order to extract moisture from the polycotton for 10 min, after that the first autoclave containing CO2 and polycotton is kept in batch mode and then connected to the second autoclave 3 by opening the valve 60 between the autoclaves.

[0084] The supercritical phase containing the ionic liquid and co-solvent diffuses within the polycotton and solvate the cotton for a duration of 70 min. At the end of this phase, autoclaves are depressurized through the second autoclave where the ionic liquid, solvated cellulose and co-solvent will be trapped in trap 37. The polyester fibres will remain intact in the first reactor 5.

[0085] Illustrated in Fig. 2 is also a CO2 recovery / filtration tank 7, pump 10, cooler 11 , and a heater 12.

[0086] The system may also contain a pressure sensor 13 for the second vessel 3, a pressure sensor 14 for the first vessel, temperature sensor 15 for the second vessel, a temperature sensor 16 for the first vessel, flow sensors 17, 18, heaters 19, 20, stirrers 21 , 22, and a mixer 23.

[0087] Below is described a specific example of the process described above.

[0088] Two connected high-pressure cells 3, 5 of 500 ml each were used. 100 g of blended polycotton textile waste 2 with a composition 60 wt.% polyester - 40 wt.% cotton was provided in the first vessel / high-pressure cell 5. 30 mol% of 1 -butyl-3- methylimidazolium acetate and 10 mol% of methanol were introduced in the second cell 3. The cells were separated by closing the valve 60. Thereafter, CC^was fed into the two vessels 3, 5 until reaching a pressure of 100 bar (10 MPa) with a pressurization rate of 2 bar (200 KPa) / min and temperature of 110°C. In the second cell 3, the supercritical CO2 dissolve ionic liquid with the help of the co-solvent methanol and therefore forms a supercritical phase in a batch mode. In the first cell 5, a semicontinuous flow of CO2 was maintained for 25 min at the same pressure and temperature in order to dry the textile and extract any impurities. At the end of this duration, a batch system is maintained in the first cell 5 as well.

[0089] The valve 60 between the two cells 3, 5 was thereafter opened and the supercritical phase containing the ionic liquid and co-solvent from the second cell 3 was allowed to diffuse to cell 5 until reaching an equilibrium. The supercritical phase then diffuses within the 60 wt.% polyester - 40 wt.% cotton textile 2 and swell it. Since the supercritical phase has affinity with the cellulosic material, it will solvate the cellulosic material without its depolymerization. After 65 minutes, the first cell 5 was depressurized at a rate of 1.5 bar (150 KPa) / min and the solvated cellulosic material was trapped in the trap 37 and the recovered polyester remains in the bottom of the first cell 5.

[0090] A further example of the process is described below, wherein ionic liquid and enzymes are dissolved in the supercritical / subcritical fluid .

[0091] The same conditions as in the example above are used, but the supercritical phase comprises 20 mol% of 1-butyl-3-methylimidazolium acetate and also cellulases (enzyme). 2 g of cellulases were used for each 100 g of cellulose present in the polycotton. 8 mol% of water and 3 mol% of ethanol were used to improve the solubility of cellulases and 1-butyl-3-methylimidazolium acetate) in the supercritical CO2. The pressure and temperature used in this example were 140 bar (14 MPa) and 80°C and the separation duration was 85 minutes.

[0092] The fibres recovered from the above examples of the process were used to produce new yarns. The recovered polyester went through drawing and carding and then spun into new polyester fibres.

[0093] Solvated cellulose present in the co-solvent and 1-butyl-3-methylimidazolium acetate went through a solvent exchange to replace the liquid phase with a pure ionic liquid and then went through wet spinning in order to produce lyocell fibres.

[0094] In another embodiment of the process, illustrated in Fig. 3, the blended textile is provided in a vessel 40, wherein the vessel 40 is divided in a first and second compartment 51 , 52 separated by a perforated support 50 (the perforations may for example have round shape and a diameter of about 2 mm). The blended textile is provided on the support 50 in the first compartment 51 of the vessel 40. The ionic liquid is provided in the second compartment 52. Supercritical or subcritical fluid is entered into or formed in the vessel 40 such that the ionic liquid in the second compartment 52 is dissolved in the supercritical or subcritical fluid forming a supercritical or subcritical phase (indicated as grid pattern in the vessels), thereby the blended textile in the first compartment 51 is contacted with the supercritical or subcritical phase, and the cellulosic fibres of the blended textile becomes solvated in the supercritical or subcritical phase (not illustrated). The supercritical or subcritical phase is depressurized. Solvated cellulosic fibres is collected in / from the second compartment 52. Non-dissolved non-cellulosic fibres is collected in / from the first compartment 51 .

[0095] In a specific example of the process described above a 500 mL high-pressure cell / vessel 40 was used. 100 mg of blended polycotton textile waste with a composition of 50 wt.% polyester - 50 wt.% cotton was introduced in the vessel 40 in the first compartment 51 on the support 50. The second compartment 52 in the bottom of the cell 40 contained 22 mol% of 1-allyl-3-methylimidazolium chloride and 12 mol% of ethanol. CO2 was introduced to the high-pressure cell 40 in a batch mode until reaching a pressure of 150 bar (15 MPa) with a pressurization rate of 2.5 bar (250 KPa) / min and a temperature of 120°C. The supercritical CO2 dissolved 1 -allyl-3- methylimidazolium chloride with the help of the co-solvent (ethanol) and formed a supercritical phase that diffused to the polycotton textile and swells it. For 70 min, the supercritical phase solvated / dissolved only the cellulosic material, while the polyester fibres remain intact. At the end of these 70 min, the high-pressure cell 40 is depressurized at a rate of 3 bar (300 KPa) / min and the solvated cellulosic material is collected in / from the second compartment 52 and the recovered polyester remains in the bottom of the first compartment 51 of the high-pressure cell 40.

[0096] In Table 1 below is shown results of using the process discussed immediately above. 50-50 wt.% of a polycotton blend was dried at 80 °C for 4 h and weighed (second column) before starting the process. After the process was completed, recovered undissolved polyester fibres were dried at 80°C for 4 h and then weighed again, see column 3. In columns 4 and 5 are shown the wt.% of recovered dissolved / solvated cotton fibres and recovered undissolved polyester fibres, respectively. As can be seen, almost a full separation of cotton and polyester fibres was obtained. The experiment was repeated four times in the same conditions and is shown as samples 1 -4 in the table.

[0097] Table 1

[0098] A weight loss method was used to quantify the amount of the dissolved / solvated cellulose and undissolved polyester. This can be done through thermogravimetry analysis (TGA), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and / or mechanical testing.

[0099] This clearly shows that the process outlined above can be used for separating blended textile materials, such as polycotton.

[0100] The above-described process allows the separation of cellulosic and non-cellulosic material as we can see in Table 1 in the case of polycotton blend. A textile reference of pure polyester has been treated in the same conditions of pressure, temperature, ionic liquid and co-solvent. The properties of the reference polyester fibre before and after the supercritical / subcritical exposure were the same as well as the appearance of the fibres. The weight loss observed after the extraction experiment in Table 1 shows the dissolution of cellulose in the supercritical / subcritical phase and it correspond to almost half the weight of the initial 50-50 polycotton, which shows that we have separated almost the entire cellulosic material in the polycotton blend.

[0101] The above-described process can be used for different types of fibre blends such as cotton-acrylic blends. This type of blend is widely used for apparel, outwear, home textiles and accessories. Supercritical and subcritical phase swell both the acrylic and cellulosic material of the blend and has the power of solvating only cellulosic material through the same mechanism as explained above. The acrylic material swell in presence of the supercritical or subcritical phase but cannot be dissolved. However, this swelling facilitates the penetration of the supercritical-subcritical phase into the blend and therefore the cellulosic material dissolution.

[0102] Textile materials comprising synthetic fibres such as polypropylene, polyethylene, polyamide (nylon), aramid and novoloid, mixed with cellulosic material present a good affinity with supercritical / subcritical fluids and therefore allow a good diffusion of these fluids into the synthetic / cellulosic blend. That means that the supercritical / subcritical phase of the above-described process can penetrate in the synthetic fibre / cellu losic material blend and dissolve / solvate only the cellulosic part without impacting the synthetic fibres such as polypropylene, polyethylene or polyamide.

[0103] In the case of man-made fibres, carbon fibres, derived from petrochemicals and synthetic polymers like polyester or polyamide, the supercritical or subcritical phase can be used to clean or extract impurities from the carbon fibres, to impregnate specific components or polymers within the porous structure of carbon fibres but the supercritical / subcritical phase cannot dissolve or deteriorate the properties of the high performance material composed of carbon atoms bonded together in crystalline structure. In the case where we have a carbon fibre / cellulose blend treated with the supercritical or subcritical phase, the supercritical of subcritical phase will diffuse within the porous structure of carbon fibre and within the cellulose and can dissolve / solvate only the cellulosic part.

[0104] In the case of natural fibres such as wool or silk, which are composed of proteins, they can be treated, modified, dyed with supercritical and subcritical fluids but not dissolved / solvated. In the case where wool or silk are blended with cotton and treated with the above-described process, supercritical or subcritical fluid can solvate only the cellulosic material.

[0105] The cellulosic material present on those blends can be natural fibres such as cotton, linen, flax, hemp, jute, ramie and bamboo, and also, regenerated cellulosic fibres such as lyocell, modal, rayon and viscose.

[0106] Below follows an example in which elastane was separated form a blend of cotton and polyester.

[0107] 100 g of a textile blend containing 60 wt.% cotton, 35 wt.% of polyester and 5 wt.% of elastane was introduced in a first high pressure vessel. Thereafter CO2 is introduced into the vessel containing the textile blend to reach a pressure of 100 bar (10 MPa) and a temperature of 60°C as well as a co-solvent (in this case DMSO, 35 mol%) until equilibrium was reached.

[0108] The supercritical phase dissolved the elastane from the blend of 60 wt.% cotton, 35 wt.% of polyester and 5 wt.% elastane in 22 minutes. At the end of this extraction step, the high pressure cell was depressurized and the elastane dissolvent collected in a separator.

[0109] Thereafter, a textile blend comprising only cotton and polyester remained. 80 g of this textile blend was introduced into the same high pressure vessel as well as 25% mol of 1-Ethyl-3-methylimidazolium diethyl phosphate (part of the family of ionic liquid imidazolium-based ionic liquids). Following this step, the carbon dioxide was introduced as well as co-solvent (DMSO 5 mol%). The supercritical phase containing CO2, DMSO and ionic liquid diffused within the polycotton blend and solvated the cellulose (while remaining polymer) while the polyester remained solid and intact. At the end of this phase, the autoclave is depressurized where the ionic liquid, solvated cellulose and co-solvent will be trapped in a trap. The polyester fibres will remain intact in the high pressure vessel

[0110] In the next example acrylic is separated from a blend of cotton and acrylic. In a first high pressure vessel, 60 g of a textile blend containing 75 wt.% cotton, 25 wt.% acrylic was introduced. Thereafter, CO2 was introduced into the vessel containing the textile waste to reach a pressure of 120 bar (12 MPa) and a temperature of 75°C as well as 30 mol% of 1-Ethyl-3-methylimidazolium methyl ethyl phosphate and 5 mol% of Dimethylformamide (DMF). The supercritical phase solvated the cotton from the blend of cotton / acrylic in 35 minutes. At the end of this extraction step, the high pressure cell was depressurized and the ionic liquid, solvated cellulose and co-solvent were trapped in a trap. The acrylic fibres remained intact in the high pressure vessel

[0111] In the next example nylon and cotton are separated form a blend of nylon-cotton using subcritical conditions. In a first high pressure vessel 30 g of a textile blend containing 10 wt.% cotton, 90 wt.% nylon was introduced. After that, CO2 was fed into the vessel containing the blended textile to reach a pressure of 55 bar (5.5 MPa) and a temperature of 85°C as well as 37 mol% of 1-Ethyl-3-methylimidazolium diethyl phosphate and 10 mol% of methanol. The supercritical phase solvated the cotton from the blend of cotton / nylon in 45 minutes. At the end of this extraction step, the high- pressure cell was depressurized and the ionic liquid, solvated cellulose (cotton) and co-solvent ware trapped in a trap. The nylon fibres remains intact in the high pressure vessel.

[0112] In another example, wool and cotton were separated from a blend of 55 wt.% wool and 45 wt.% cotton using supercritical carbon dioxide. In a first high pressure vessel 45 g of this 55 wt.% wool and 45 wt.% cotton blend was introduced. After that, CO2 was fed into the vessel containing the blended textile to reach a pressure of 210 bar (21 MPa) and a temperature of 61°C as well as 60 mol% of tetrabutylphosphonium chloride and 5 mol% of dimethylformamide. A mixing system was used in the vessel in order to obtain a homogeneous supercritical phase in a shorter time and obtain a more efficient extraction of the cellulosic fibres. The supercritical phase solvated the cotton from the blend of cotton / wool in 33 minutes. At the end of this extraction step, the high pressure cell was depressurized with a depressurization rate of 10 bar (1 MPa) / min and the ionic liquid, solvated cellulose (cotton) and co-solvent were trapped in a trap. The wool fibres remains intact in the high pressure vessel.

[0113] In another example, polyester and viscose were separated from a blend of 65 wt.% polyester and 35 wt.% viscose using supercritical carbon dioxide. In a first high pressure vessel 100 g of this 65 wt.% polyester and 35 wt.% viscose blend was introduced. After that, CO2 was fed into the vessel containing the blended textile to reach a pressure of 130 bar (13 MPa) and a temperature of 75°C as well as 45 mol% of N-butylpyridinium chloride and 15 mol% of dimethylformamide. A mixing system was used in the vessel in order to obtain a homogeneous supercritical phase in a shorter time and obtain a more efficient extraction of the cellulosic fibres. The supercritical phase solvated the viscose from the blend of polyester / wool in 28 minutes. At the end of this extraction step, the high-pressure cell was depressurized with a depressurization rate of 7 bar (7 MPa) / min and the ionic liquid, solvated cellulose (viscose) and co-solvent were trapped in a trap. The polyester fibres remains intact in the high pressure vessel.

[0114] In another example modal and spandex were separated from a blend of 96 wt.% modal and 4 wt.% spandex using supercritical carbon dioxide. In a first high pressure vessel 100 g of this 96% modal and 4 wt.% spandex blend was introduced. After that, CO2 was fed into the vessel containing the blended textile to reach a pressure of 80 bar (80 MPa) and a temperature of 73°C as well as 59 mol% of tetraethylammonium chloride and 27 mol% of DMSO. A stirring rate at approximately 1200 rpm was used in the vessel in order to obtain a homogeneous supercritical phase in a shorter time and obtain a more efficient extraction of the cellulosic fibres. The supercritical phase solvated the modal from the blend of modal / spandex in 20 minutes. At the end of this extraction step, the high pressure cell was depressurized with a depressurization rate of 17 bar (1.7 MPa) / min and the ionic liquid, solvated cellulose (modal) and co-solvent were trapped in a trap. The spandex fibres remain intact in the high pressure vessel.

[0115] It is important to mention that the pressure, temperature, pressurization and depressurization rates (affecting density and viscosity of the supercritical / subcritical phase), type and concentration of ionic liquid and any co-solvent used, and duration of treatment should be optimized for the different materials mentioned above (such as waste material, the amount of cellulose in the blended textile, degree and type of crystallinity of the cellulose, the non-cellulosic components in the blended textile etc.) in order to reach a good / optimal diffusivity, selective extraction to cellulosic material and mass transfer without impacting the properties of the non-cellulosic fibres. Suboptimal conditions can still solvate the cellulose from the blended textile, but not fully.

[0116] In this process supercritical phase as well as subcritical phase might be used to separate the cellulosic from the non-cellulosic material. In for example the case of subcritical CO2, we have low conditions of pressure and temperature, i.e. below supercritical points (e.g. 50 bar 5 MPa) and 40°C) that exhibit a selective solubility for certain compounds and by adding co-solvent to this phase, we can fine tune the polarity of the subcritical CO2 phase to extract further components.

[0117] Instead of carbon dioxide, subcritical water can be used, the pressures should the be below 218 bar (21 .8 MPa) and the temperature below 374 °C. The subcritical water can also be used for the separation step but at very mild to low conditions of pressure and temperature so the cellulosic and non-cellulosic material will not be deteriorated or depolymerized.

[0118] Further, subcritical ethanol can be used at pressures below 61 .4 bar (6.14 MPa) and a temperature below 243 °C. The subcritical ethanol has a natural affinity towards cellulose, which facilitate its dissolution from a cellulosic-non cellulosic blend. In this case in general, a low pressure and temperature, i.e. below supercritical points (e.g. 40 bar (4 MPa) and 100 °C) is used so the subcritical ethanol will not impact the properties of the non-cellulosic material.

Claims

CLAIMS1 . Process for separating and recovering fibres of blended textiles, comprising:- providing (100) a blended textile comprising at least a first fibre type being cellulosic fibres and at least a second fibre type being non-cellulosic fibres,- dissolving (101 ) a polar ionic liquid in a supercritical or subcritical phase,- contacting (102) the blended textile with the supercritical or subcritical phase,- allowing the supercritical or subcritical phase to diffuse into the blended textile, thereby solvating the cellulosic fibres in the supercritical or subcritical phase,- depressurizing (103) the supercritical or subcritical phase,- collecting cellulosic fibres (104) solvated in the supercritical or subcritical phase,- collecting non-dissolved non-cellulosic fibres (105).

2. The process of claim 1 , wherein the cellulosic fibres of the blended textile are natural or man-made cellulosic fibres selected from cotton, hemp, linen, ramie, modal, lyocell, bamboo, sisal, viscose, abaca, kenaf, jute or combinations thereof.

3. The process of claim 1 or 2, wherein the non-cellulosic fibres of the blended textile are selected from polyester, wool, nylon, elastane, silk, acrylic, polypropylene, polyethylene, polyamide, modacrylic, carbon fibre, aramid, novoloid, or combinations thereof.

4. The process of any of the preceding claims, wherein the supercritical or subcritical phase comprises a co-solvent.

5. The process of any of claims 1 to 4, wherein the blended textile contacted with the supercritical or subcritical phase is in pieces of 1 cm2or larger.

6. The process of any of claims 1 to 5, wherein the supercritical or subcritical phase comprises carbon dioxide.

7. The process of any of claims 1 -6, wherein the ionic liquid is selected from imidazolium-based ionic liquids, phosphonium-based ionic liquids, pyridinium-based ionic liquids, ammonium-based ionic liquids or any combination thereof.

8. The process of any of claims 1-7, wherein the amount of ionic liquid dissolved in the supercritical or subcritical phase is 0.05- 60 mol%.

9. The process of any of claims 4-8, wherein the co-solvent is a polar co-solvent selected from ethanol, methanol, acetone, dimethyl sulfoxide, ethyl acetate, propylene carbonate, acetic acid, formic acid, water or any combination thereof.

10. The process of any of claims 4-9, wherein the amount of co-solvent in the supercritical or subcritical phase is 0.1-40 mol%.11 . The process of any of claims 1 to 10, wherein an enzyme is dissolved in the supercritical or subcritical phase.

12. The process of claim 11 , wherein the enzyme is an enzyme selected from cellulases, endoglucanases, exoglucanases, / 3-glucosidases or combinations thereof.

13. The process of any of claims 11 or 12, wherein the amount of enzyme dissolved in the supercritical or subcritical phase may is 5 to 30 g per 100 g of cellulose in the blended textile.

14. The process of any of claims 1 -13, wherein the supercritical or subcritical phase further comprises N-Methylmorpholine N-oxide, dimethyl sulfoxide (DMSO), dimethyllacethamide (DMAc), and / or lithium chloide (LiCI).

15. The process of any of the preceding claims, wherein the supercritical / subcritical phase is brought into contact (102) with the blended textile for at least 20 minutes.

16. The process of any of the preceding claims, wherein the supercritical / subcritical phase and the blended textile are present in a mass ratio between 0.5:1 to 50:1 .

17. The process of any of the preceding claims, further comprising a step of removing colour and / or additive from the resulting cellulosic fibres (106) and / or non- cellulosic fibres (107).

18. The process of any of the preceding claims, comprising a pre-step (100a, 100b) of extracting any moisture, dirt, grease or sizing agent from the blended textile material and / or to remove colour and / or additive from the blended textile before the blended textile is brought into contact (102) with the supercritical / subcritical phase.

19. The process of any of the preceding claims, wherein the blended textile is provided (100) in a vessel (40) divided into a first and second compartment (51 , 52) by a perforated support (50), wherein the blended textile is provided on said support (50) in said first compartment (51 ) and a polar ionic liquid or a polar ionic liquid and a polar co-solvent is provided in said second compartment (52), wherein the supercritical or subcritical phase is entered into or formed in the vessel (40), allowing the ionic liquid to dissolve in the supercritical or subcritical phase in the second compartment (52), wherein the blended textile in the first compartment (51 ) is contacted with the supercritical or subcritical phase, thereby solvating the cellulosic fibres in the supercritical or subcritical phase, and after depressurizing the supercritical or subcritical phase, collecting the solvated cellulosic fibres in / from the second compartment (52), and collecting non-dissolved non-cellulosic fibres in / from the first compartment (51 ).

20. The process of any of the preceding claims 1 -18, wherein the blended textile is provided (100) in a first vessel (5) and a polar ionic liquid (4) or a polar ionic liquid and a polar co-solvent is provided in a second vessel (3), supercritical or subcritical phase is entered into or formed in the second vessel (3), allowing the ionic liquid to dissolve in the supercritical or subcritical phase (101 ), transferring the supercritical or subcritical phase from the second vessel (3) to the first vessel (5), contacting the blended textile (2) in the first vessel (5) with the supercritical or subcritical phase, thereby solvating the cellulosic fibres in the supercritical or subcritical phase, after depressurizing the supercritical or subcritical phase, removing the depressurized supercritical or subcritical phase with solvated cellulosic fibres from the first vessel (5), and collecting the solvated cellulosic fibres.

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