Supercritical carbon dioxide anhydrous decoloration system and method for polyester fabric

Abstract

The invention discloses a supercritical carbon dioxide anhydrous decoloration system and method for polyester fabrics, which utilizes supercritical carbon dioxide fluid to replace traditional water media and chemical solvents to realize efficient decoloration treatment of the polyester fabrics, and avoids the problem of wastewater pollution and the use of harmful chemical solvents. And meanwhile, the supercritical carbon dioxide fluid can be recovered and reused after being decolored, so that efficient utilization of resources is realized. After decolorization, the color intensity deviation sigma K / S of the polyester fabric is less than or equal to 0.20, the decolorization rate is more than or equal to 95%, the breaking strength loss rate is less than or equal to 10%, and the dye recovery rate is more than or equal to 85%. Besides, after the polyester fabric is decolored for more than 20 times, the decoloring efficiency can still be kept to be greater than or equal to 95%, the stability and the economical efficiency are ensured, the efficient decoloring of the polyester fabric is realized, the method has the advantages of simple process, high environmental protection property, small fiber damage and the like, and the problems of high water consumption, high pollution, large fiber damage and the like in the decoloring treatment process of the polyester fabric are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyester fabric decolorization, and more particularly to a supercritical carbon dioxide non-water decolorization system for polyester fabric and a method thereof. BACKGROUND

[0002] Polyester fabric is a synthetic textile made from polyester fibers, usually referring to fabrics made from polyethylene terephthalate or other types of polyester resin fibers. Polyester is one of the most widely used synthetic fibers in the world, widely used in clothing, home textiles, industrial fabrics, and other fields. Polyester fabric has become an important raw material in the textile industry due to its excellent performance, relatively low production cost, and durability. However, the production of polyester fabric relies on non-renewable petroleum resources and is difficult to degrade in the natural environment, increasing the burden of waste. Therefore, the recycling of polyester fabric has always been the focus of the industry.

[0003] Current polyester recycling methods mainly include mechanical recycling and chemical recycling. Mechanical recycling involves crushing, melting, and re-spinning waste polyester fabric to produce new polyester fibers, which is suitable for processing large amounts of homogeneous waste, has low cost and simple processing process, but the quality of the recycled material may be poor, and it cannot handle complex mixed waste. Chemical recycling involves decomposing polyester into monomers through chemical reactions and then synthesizing new polyester, which is suitable for processing mixed materials or waste with high impurity content, can achieve high-quality recycling, and even can handle complex waste, but has high cost, high technical requirements, and high energy consumption. In addition, during the recycling process, polyester fabric is often not a single color, and if the color is too complex, it will increase the difficulty of recycling and reprocessing, which means that polyester fabric usually needs to be decolorized to make it easier to be processed into a unified raw material before subsequent recycling and reuse. Therefore, the recycling of polyester fabric is difficult, resulting in low reuse rate.

[0004] Traditional polyester fabric decolorization treatment process relies on water medium and chemical solvents, which has problems of high water consumption, high pollution, and large fiber damage. Chemical solvents often use toxic and volatile chemicals, which harm the environment and human health, and the treatment process produces a large amount of harmful waste gas and wastewater; although water washing decolorization is more environmentally friendly, it requires a large amount of water and energy, and may cause damage to the fabric, leading to fiber aging or strength reduction. In addition, the effect of traditional decolorization methods is limited, and complex dyes cannot be completely removed, and often require multiple treatments, increasing energy consumption and production costs. Supercritical carbon dioxide fluid has similar liquid solubility and gas diffusivity, and can penetrate more efficiently into the interior of the fabric, rapidly dissolving and removing dyes or pigments, and has been widely used in the extraction field in recent years. However, its application in polyester decolorization is less studied, especially lacking efficient and low-energy industrial solutions. SUMMARY

[0005] The purpose of the present application is to overcome the above-mentioned defects existing in the prior art, and to provide a polyester fabric supercritical carbon dioxide waterless decolorization system and method, which solves the problems of high water consumption, high pollution, and large fiber damage in the polyester fabric decolorization treatment process. The present application uses supercritical carbon dioxide fluid instead of traditional water medium and chemical solvents to achieve efficient decolorization treatment of polyester fabric, avoiding wastewater pollution problems and the use of harmful chemical solvents; at the same time, supercritical carbon dioxide fluid can be recycled and reused after decolorization, reducing solvent waste and achieving efficient use of resources. Therefore, the present application has great significance for promoting the textile industry to develop in a more green and sustainable direction.

[0006] To achieve the above-mentioned purpose, the technical solutions of the present application are as follows: The application discloses a polyester fabric supercritical carbon dioxide anhydrous decoloring system, which comprises a liquid carbon dioxide storage tank 1, a first condensing device 2, a pressurizing pump 3, a heat exchanger 4, a decoloring reaction kettle 5, at least one dye collecting kettle 6 and a second condensing device 7; wherein the liquid carbon dioxide storage tank 1, the first condensing device 2, the pressurizing pump 3, the heat exchanger 4, the decoloring reaction kettle 5, the dye collecting kettle 6 and the second condensing device 7 are sequentially connected through pipelines to form a circulating loop; the decoloring reaction kettle 5 comprises an outer sleeve 51, a porous distribution pipe 52 and an inner porous sleeve 53; the inner porous sleeve 53 is located in the porous distribution pipe 52, and the porous distribution pipe 52 is located in the outer sleeve 51; a gas inlet 511 and a gas outlet 512 are formed in the bottom and the top of the outer sleeve 51 respectively; the inner porous sleeve 53 is provided with a first gas guide channel 531 and a second gas guide channel 532; one end of the gas inlet 511 is connected with the heat exchanger 4, the other end of the gas inlet 511 is communicated with the inner porous sleeve 53 through the first gas guide channel 531, one end of the gas outlet 512 is communicated with the inner porous sleeve 53 through the second gas guide channel 532, and the other end of the gas outlet 512 is communicated with the dye collecting kettle 6; the first gas guide channel 531 is used for providing a path for the carbon dioxide fluid to enter the inner porous sleeve 53 through the gas inlet 511, and the second gas guide channel 532 is used for providing a path for the carbon dioxide fluid to enter the dye collecting kettle 6 through the gas outlet 512; the inner porous sleeve 53 is provided with a through-hole structure distributed along the circumference thereof; the porous distribution pipe 52 is provided with through-holes 521 distributed along the circumference thereof; the dye collecting kettle 6 comprises a kettle body 61, a fluid inlet 62 with a throttle valve 67 is arranged at the top of one side of the kettle body 61, a gas outlet 63 with a nano-porous membrane 68 is arranged at the bottom of the other side of the kettle body 61; a pressure relief valve 64 is further arranged at the bottom of the kettle body 61, and a rack 65 is arranged at the top of the kettle body 61 and a coil pipe 66 is arranged in the kettle body 61.

[0007] The application further discloses a polyester fabric supercritical carbon dioxide anhydrous decoloring method, which adopts the decoloring system and comprises the following steps: S1, winding polyester fabric to be decolored on the outer wall of the porous distribution pipe 52; S2, treating the liquid carbon dioxide in the liquid carbon dioxide storage tank 1 through the first condensing device 2, then feeding the liquid carbon dioxide into the pressurizing pump 3, pressurizing the liquid carbon dioxide to exceed the critical pressure of carbon dioxide, feeding the liquid carbon dioxide into the heat exchanger 4, and heating the carbon dioxide to exceed the supercritical temperature; S3. The supercritical carbon dioxide discharged from the heat exchanger 4 is transported to the decolorization reactor 5 and injected through the gas inlet 511 at the bottom of the outer sleeve 51. It enters the flow channel of the inner porous sleeve 53 through the first gas guide channel 531, and then penetrates the through hole structure of the inner porous sleeve 53 and the through hole 521 of the porous distribution pipe 52, and comes into uniform contact with the polyester fabric to be decolorized. It achieves high-density directional penetration into the polyester fabric to be decolorized, thereby decolorizing the polyester fabric. S4. After decolorization, the supercritical carbon dioxide fluid carrying the dye is transported through the second gas channel 532 and the gas outlet 512 at the top of the outer sleeve 51 to at least one dye collection vessel 6. After being depressurized by a throttle valve 67, it enters the vessel body 61 of the dye collection vessel 6 through the fluid inlet 62. The temperature is adjusted to the dye collection temperature by the coil 66, and the pressure is adjusted to the dye collection pressure by the pressure relief valve 64, so that the supercritical carbon dioxide fluid carrying the dye is changed from the supercritical state to the gaseous state. Then, the dye is collected through the nanoporous membrane 68. The treated gaseous carbon dioxide is transported through the gas outlet 63 to the second condensation device 7 for further processing, so that the gaseous carbon dioxide is changed to the liquid state and recovered into the liquid carbon dioxide storage tank 1.

[0008] Implementing the embodiments of the present invention will have the following beneficial effects: This invention provides a supercritical carbon dioxide anhydrous decolorization system and method for polyester fabrics, employing a supercritical carbon dioxide system for anhydrous decolorization of polyester fabrics. Supercritical CO2 is a green solvent, not only avoiding water waste and pollution but also effectively avoiding the use of harmful solvents, thus offering better environmental protection and safety. After decolorization, the color intensity deviation σ of the polyester fabric is... K / S The decolorization rate is ≥95%, the breaking strength loss rate is ≤10%, and the dye recovery rate is ≥85%. Furthermore, after completing more than 20 decolorization cycles on polyester fabrics, the decolorization efficiency remains ≥95%, verifying the system's stability and economic efficiency. This invention achieves highly efficient decolorization of polyester fabrics using supercritical carbon dioxide technology, offering advantages such as simple process, strong environmental friendliness, and minimal fiber damage, providing an innovative solution for the sustainable development of the textile industry. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the supercritical carbon dioxide anhydrous decolorization system for polyester fabrics according to the present invention.

[0010] Figure 2 This is a schematic diagram of the decolorization reaction vessel of the present invention.

[0011] Figure 3 This is a schematic diagram of the dye collection vessel of the present invention.

[0012] Figure 4 Schematic diagram of the polyethylene terephthalate fabric before and after decolorization of Example 2 of the present application. (a) Polyethylene terephthalate fabric before decolorization (PET, K / S value after dispersion orange 30 dyeing was 13.30); (b) polyethylene terephthalate fabric after decolorization (PET, K / S value after decolorization was 0.58).

[0013] Figure 5 Schematic diagram of the polyethylene terephthalate fabric before and after decolorization of Example 3 of the present application. (a) Polybutylene terephthalate fabric before decolorization (PBT, K / S value after dispersion red 60 dyeing was 8.12); (b) polybutylene terephthalate fabric after decolorization (PBT, K / S value after decolorization was 0.40).

[0014] wherein, 1: liquid carbon dioxide storage tank; 2: first condensing device, 21: first condenser, 22: first refrigeration compressor; 3: pressurizing pump; 4: heat exchanger; 5: decolorization reaction kettle, 51: outer sleeve, 511: gas inlet, 512: gas outlet, 52: porous distribution pipe, 521: through hole, 53: inner porous sleeve, 531: first gas guiding channel, 532: second gas guiding channel; 6: dye collection kettle, 61: kettle body, 62: fluid inlet, 63: gas outlet, 64: pressure relief valve, 65: rack, 66: coil pipe, 67: throttle valve, 68: nano-porous membrane; 7: second condensing device, 71: second condenser, 72: second refrigeration compressor. DETAILED DESCRIPTION

[0015] The present application is further described in conjunction with specific examples, but in no way limited by the present application.

[0016] This invention also discloses a supercritical carbon dioxide anhydrous decolorization system for polyester fabrics. The system includes a liquid carbon dioxide storage tank 1, a first condensing device 2, a pressurizing pump 3, a heat exchanger 4, a decolorization reaction vessel 5, at least one dye collection vessel 6, and a second condensing device 7. The liquid carbon dioxide storage tank 1, the first condensing device 2, the pressurizing pump 3, the heat exchanger 4, the decolorization reaction vessel 5, the dye collection vessel 6, and the second condensing device 7 are sequentially connected by pipelines to form a circulation loop. The decolorization reaction vessel 5 includes an outer sleeve 51, a porous distribution pipe 52, and an inner porous sleeve 53. The inner porous sleeve 53 is located inside the porous distribution pipe 52, and the porous distribution pipe 52 is located inside the outer sleeve 51. The bottom and top of the outer sleeve 51 are respectively provided with a gas inlet 511 and a gas outlet 512. The inner porous sleeve 53 is provided with a first gas guiding channel 531 and a second gas guiding channel 532. One end of the gas inlet 511 is connected to the heat exchanger 4, and the other end of the gas inlet 511... The gas outlet 512 is connected to the inner porous sleeve 53 via the first gas guide channel 531, and one end of the gas outlet 512 is connected to the inner porous sleeve 53 via the second gas guide channel 532. The other end of the gas outlet 512 is connected to the dye collection vessel 6. The first gas guide channel 531 is used to provide a path for carbon dioxide fluid to enter the inner porous sleeve 53 through the gas inlet 511, and the second gas guide channel 532 is used to provide a path for carbon dioxide fluid to enter the dye collection vessel 6 through the gas outlet 512. The inner porous sleeve 53 is provided with a through-hole structure distributed along its circumference. The porous distribution pipe 52 is provided with through holes 521 distributed along its circumference. The dye collection vessel 6 includes a vessel body 61. A fluid inlet 62 with a throttling valve 67 is provided on the top side of the vessel body 61, and a gas outlet 63 with a nanoporous membrane 68 is provided on the bottom side of the vessel body 61. A pressure relief valve 64 is also provided at the bottom of the vessel body 61, as well as a frame 65 located at the top of the vessel body 61 and a coil 66 located inside the vessel body 61.

[0017] In one specific embodiment, the through hole structure of the inner porous sleeve 53 has a diameter of 5~8mm and the diameter of the inner porous sleeve 53 is 55mm.

[0018] In one specific embodiment, the diameter of the through hole 521 of the porous distribution tube 52 is 5~8mm.

[0019] In one specific embodiment, the diameter of the porous distribution tube 52 is 60 mm.

[0020] In one specific embodiment, such as Figure 2 As shown, the through hole 521 is composed of a through hole structure with the hole diameter arranged in a gradient cycle; preferably, it first gradually increases from 5mm to 8mm, and then gradually increases from 5mm to 8mm again.

[0021] In one specific embodiment, the number of dye collection vessels 6 is 2 to 4.

[0022] In a specific embodiment, the first condensing device 2 comprises a first condenser 21 and a first refrigeration compressor 22.

[0023] In a specific embodiment, the second condensing device 7 comprises a second condenser 71 and a second refrigeration compressor 72.

[0024] In a specific embodiment, the nano-porous membrane 68 comprises a ceramic membrane or a polymer ultrafiltration membrane, with a pore size of 1-10 nm. Preferably, the nano-porous membrane 68 is nano-alumina or nano-zirconia.

[0025] The present application also discloses a polyester fabric supercritical carbon dioxide anhydrous decolorization method, which adopts the decolorization system according to any embodiment of the present application, and specifically comprises the following steps: S1, winding the polyester fabric to be decolored on the outer wall of the porous distribution pipe 52.

[0026] S2, treating the liquid carbon dioxide in the liquid carbon dioxide storage tank 1 by the first condensing device 2, then entering the pressurizing pump 3, and delivering to the heat exchanger 4 after being pressurized to exceed the critical pressure of carbon dioxide, so that the carbon dioxide passing through the heat exchanger 4 is heated to exceed the supercritical temperature.

[0027] S3, delivering the supercritical carbon dioxide discharged from the heat exchanger 4 to the decolorization reaction kettle 5, injecting through the gas inlet 511 at the bottom of the outer sleeve 51, entering the flow channel of the inner porous sleeve 53 through the first gas guide channel 531, then penetrating the through-hole structure of the inner porous sleeve 53 and the through-hole 521 of the porous distribution pipe 52, and uniformly contacting with the polyester fabric to be decolored, so as to perform high-density directional penetration on the polyester fabric to be decolored, thereby improving the stripping efficiency and uniformity of the dye.

[0028] S4, after the decolorization is completed, delivering the supercritical carbon dioxide fluid carrying the dye through the second gas guide channel 532 to the at least one dye collection kettle 6 through the gas outlet 512 at the top of the outer sleeve 51, reducing the pressure through the throttle valve 67, then entering the kettle body 61 of the dye collection kettle 6 through the fluid inlet 62, adjusting the temperature to the dye collection temperature by using the coil pipe 66, adjusting the pressure to the dye collection pressure by using the pressure relief valve 64, so as to change the supercritical state of the supercritical carbon dioxide fluid carrying the dye into a gaseous state, reduce the solubility of the dye in the carbon dioxide, then collect the carried dye through the nano-porous membrane 68, and avoid that the gaseous carbon dioxide carries the dye molecules carried in the decolorization process into the next decolorization cycle, and deliver the treated gaseous carbon dioxide to the second condensing device 7 through the gas outlet 63 for treatment, so as to change the gaseous carbon dioxide into a liquid state, and recycle to the liquid carbon dioxide storage tank 1.

[0029] In a specific embodiment, in step S2, the flow rate of the liquid carbon dioxide is 100-400 kg / h.

[0030] In a specific embodiment, in step S2, the pressurizing pressure of the pressurizing pump 3 is controlled to be 8-30 MPa, and the heating temperature of the heat exchanger 4 is controlled to be 70-130℃.

[0031] In a specific embodiment, in step S3, the time for decolorization is 10-120 min.

[0032] In a specific embodiment, in step S4, the dye collection temperature is 20-60℃, and the dye collection pressure is 1-8 MPa.

[0033] In a specific embodiment, in step S4, when the dye collection kettle 6 is a multi-stage dye collection kettle 6 composed of 2-4 kettles, the dye collection pressure of each dye collection kettle 6 is arranged in a gradient decreasing order, so as to gradiently collect the dyes removed in the decolorization circulation process.

[0034] In a specific embodiment, in step S4, when the dye collection kettle 6 is a multi-stage dye collection kettle 6 composed of 2 kettles, the dye collection pressure of the first dye collection kettle 6 through which the supercritical carbon dioxide fluid carrying the dyes passes is 4-8 MPa, and the dye collection pressure of the second dye collection kettle 6 through which the supercritical carbon dioxide fluid subsequently passes is 1-4 MPa, so as to gradiently collect the dyes removed in the decolorization circulation process.

[0035] In a specific embodiment, in step S4, when the dye collection kettle 6 is a multi-stage dye collection kettle 6 composed of 3 kettles, the dye collection pressure of the first dye collection kettle 6 through which the supercritical carbon dioxide fluid carrying the dyes passes is 8 MPa, and the dye collection pressure of the second and third dye collection kettles 6 through which the supercritical carbon dioxide fluid subsequently passes is 5 MPa and 2 MPa, respectively.

[0036] In a specific embodiment, in step S4, when the dye collection kettle 6 is a multi-stage dye collection kettle 6 composed of 4 kettles, the dye collection pressure of the first dye collection kettle 6 through which the supercritical carbon dioxide fluid carrying the dyes passes is 8 MPa, and the dye collection pressure of the second, third and fourth dye collection kettles 6 through which the supercritical carbon dioxide fluid subsequently passes is 6 MPa, 4 MPa and 1 MPa, respectively.

[0037] In a specific embodiment, the polyester fabric to be decolored includes one or more than two kinds of blended fabric or composite coated fabric selected from the group consisting of polyethylene terephthalate fabric (PET), polybutylene terephthalate fabric (PBT) and polytrimethylene terephthalate fabric (PTT).

[0038] In a specific embodiment, the dyes include at least one selected from the group consisting of disperse dyes, reactive disperse dyes, mordant dyes and natural dyes derived from biomass.

[0039] The following is a specific embodiment Embodiment 1 The polyester fabric supercritical carbon dioxide anhydrous decolorization system of the embodiment comprises a liquid carbon dioxide storage tank 1, a first condensing device 2, a pressurizing pump 3, a heat exchanger 4, a decolorization reaction kettle 5, at least one dye collection kettle 6, and a second condensing device 7; wherein the liquid carbon dioxide storage tank 1, the first condensing device 2, the pressurizing pump 3, the heat exchanger 4, the decolorization reaction kettle 5, the dye collection kettle 6, and the second condensing device 7 are sequentially connected through pipelines to form a circulating loop; the decolorization reaction kettle 5 comprises an outer sleeve 51, a porous distribution pipe 52, and an inner porous sleeve 53; the inner porous sleeve 53 is located in the porous distribution pipe 52, and the porous distribution pipe 52 is located in the outer sleeve 51; the bottom and the top of the outer sleeve 51 are respectively provided with a gas inlet 511 and a gas outlet 512; the inner porous sleeve 53 is provided with a first gas guide passage 531 and a second gas guide passage 532; one end of the gas inlet 511 is connected with the heat exchanger 4, the other end of the gas inlet 511 is connected in communication with the gas inlet of the first gas guide passage 531, the gas outlet of the first gas guide passage 531 is arranged in the inner porous sleeve 53, the gas inlet of the second gas guide passage 532 is arranged in the inner porous sleeve 53, the gas outlet of the second gas guide passage 532 is connected in communication with the gas outlet 512, the other end of the gas outlet 512 is connected in communication with the dye collection kettle 6, and the gas outlet of the first gas guide passage 531 and the gas inlet of the second gas guide passage 532 are kept in a non-communicating state; the first gas guide passage 531 is used to provide a path for the carbon dioxide fluid to enter the inner porous sleeve 53 through the gas inlet, and the second gas guide passage 532 is used to provide a path for the carbon dioxide fluid to enter the dye collection kettle 6 through the gas outlet; the inner porous sleeve 53 is provided with a through-hole structure distributed along the circumference thereof; the porous distribution pipe 52 is provided with through-holes 521 distributed along the circumference thereof; the dye collection kettle 6 comprises a kettle body 61, the kettle body 61 is provided on one side and at the top thereof with a fluid inlet 62 provided with a throttle valve 67, the kettle body 61 is provided on the other side and at the bottom thereof with a gas outlet 63 provided with a nano-porous membrane 68; the kettle body 61 is further provided at the bottom thereof with a pressure relief valve 64, and a rack 65 at the top of the kettle body 61 and a coil pipe 66 in the interior of the kettle body 61.

[0040] The pore diameter of the through-hole structure of the inner porous sleeve 53 is 5-8 mm, and the diameter of the inner porous sleeve 53 is 55 mm. The diameter of the porous distribution pipe 52 is 60 mm, and the through-holes 521 distributed thereon are composed of a through-hole structure with a gradient circulating arrangement of pore diameters; preferably, the pore diameter is gradually increased from 5 mm to 8 mm first, and then again gradually increased from 5 mm to 8 mm. The number of the dye collection kettles 6 is 2. The first condensing device 2 comprises a first condenser 21 and a first refrigeration compressor 22. The second condensing device 7 comprises a second condenser 71 and a second refrigeration compressor 72. The nano-porous membrane 68 is nano-alumina or nano-zirconium dioxide, and the pore diameter is 1-10 nm.

[0041] Example 2 The polyester fabric supercritical carbon dioxide anhydrous decolorization method of the present example adopts the decolorization system of Example 1 and specifically comprises the following steps: S1, 5 kg of polyethylene terephthalate fabric (PET, K / S value of 13.30 after dispersion orange 30 dyeing) is wound on the outer wall of the multi-hole distribution pipe 52.

[0042] S2, open the liquid carbon dioxide storage tank 1, and introduce liquid carbon dioxide to make the carbon dioxide flow rate 400 kg / h, which is treated by the first condensing device 2 and then enters the pressurizing pump 3, is pressurized to 26 MPa, and is then delivered to the heat exchanger 4 to heat the carbon dioxide passing through the heat exchanger 4 to 120℃.

[0043] S3, the supercritical carbon dioxide discharged from the heat exchanger 4 is delivered to the decolorization reactor 5, is injected through the gas inlet 511 at the bottom of the outer sleeve 51, enters the flow channel of the inner multi-hole sleeve 53 through the first gas guide channel 531, and then penetrates the through-hole structure of the inner multi-hole sleeve 53 and the through-hole 521 of the multi-hole distribution pipe 52 to uniformly contact with the polyester fabric to be decolorized, and high-density directional penetration is performed on the polyester fabric to be decolorized for 100 min.

[0044] S4, after the decolorization is completed, the supercritical carbon dioxide fluid carrying the dyes is delivered to the two-stage dye collection tank 6 through the second gas guide channel 532 through the gas outlet 512 at the top of the outer sleeve 51 in sequence, the dye collection tank 6 through which the supercritical carbon dioxide fluid carrying the dyes flows first is the first dye collection tank, and the dye collection tank 6 through which the supercritical carbon dioxide fluid carrying the dyes flows later is the second dye collection tank, specifically: the supercritical carbon dioxide fluid carrying the dyes is reduced in pressure through the throttling valve 67, enters the tank body 61 of the dye collection tank 6 through the fluid inlet 62, and the temperature is adjusted to 30℃ by the coil 66, and the pressure is adjusted to 8 MPa by the pressure relief valve 64, so that the supercritical carbon dioxide fluid carrying the dyes changes from a supercritical state to a gaseous state, the solubility of the dyes in carbon dioxide is reduced, and then the dyes carried are collected by the nano-porous membrane 68, and the gaseous carbon dioxide after treatment is delivered to the second dye collection tank through the gas outlet 63, and the treatment process is the same as that of the first dye collection tank, the temperature is adjusted to 30℃ by the coil 66, and the pressure is adjusted to 4 MPa by the pressure relief valve 64, and then the gaseous carbon dioxide is changed to liquid state by the second condensing device 7, and is recovered to the liquid carbon dioxide storage tank 1. The carbon dioxide recovered to the storage tank is used for decolorization of polyester fabric for 21 times, and the recycling of the recovered carbon dioxide is completed.

[0045] The K / S value of the polyester fabric of the present application is determined by an X-rite color-eye 7000A colorimeter, and the color intensity deviation of the polyester fabric is calculated from the K / S value data. The color intensity deviation can be calculated according to formulas (1) and (2):

[0046] The decolorization rate of the present application is determined by the K / S value of the polyester fabric before and after decolorization, and is calculated from formula (3):

[0047] The dye recovery rate of the present application is determined by the weight of the polyester fabric before and after decolorization and the decolorization rate, and is calculated from formula (4):

[0048] The breaking strength of the polyester fabric of the present application is determined according to GB / T 3923.1-2013 “Textiles- Determination of tensile properties of fabrics- Part 1: determination of breaking strength and elongation at break (strip method)”, and the strength loss rate of the polyester fabric is determined by the breaking strength of the polyester fabric before and after decolorization, and is calculated from formula (5):

[0049] According to the above experimental method and calculation steps, after supercritical carbon dioxide decolorization cycle and dye collection, the K / S value of the polyethylene terephthalate fabric decreases from 13.30 to 0.58, the color intensity deviation σ K / S decreases from 0.23 to 0.20, the decolorization rate is 95.63%, the breaking strength loss rate is 8.60%, and the dye recovery rate is 86.31%. In addition, after 21 times of carbon dioxide recycling, the decolorization efficiency of the polyethylene terephthalate fabric can still reach 95.32%.

[0050] Example 3 Compared with Example 2, the difference is that: S1, 4 kg of polybutylene terephthalate fabric (PBT, K / S value after dispersion red 60 dyeing is 8.12) is wound on the outer wall of the multi-hole distribution pipe 52.

[0051] S2, open the liquid carbon dioxide storage tank 1, and introduce liquid carbon dioxide to make the carbon dioxide flow rate 300 kg / h, which is treated by the first condensing device 2 and then enters the pressurizing pump 3. After being pressurized to 28 MPa, it is delivered to the heat exchanger 4, so that the carbon dioxide passing through the heat exchanger 4 is heated to 100℃.

[0052] S3, the polyester fabric to be decolorized is decolorized for 110 min according to the step S3 of Example 2.

[0053] S4, after the decolorization is completed, the dye removed in the decolorization cycle process is collected according to the procedure S4 of Example 2, with the difference that: in the first dye collection tank, the temperature is adjusted to 36℃ by the coil pipe 66, and the pressure is adjusted to 7 MPa by the pressure relief valve 64, so that the supercritical carbon dioxide fluid carrying the dye changes from a supercritical state to a gaseous state, the solubility of the dye in carbon dioxide is reduced, and then the carried dye is collected through the nano-porous membrane 68, the gaseous carbon dioxide after treatment is transported to the second dye collection tank through the gas outlet 63, and the treatment process is the same as the first dye collection tank, the temperature is adjusted to 36℃ by the coil pipe 66, and the pressure is adjusted to 3 MPa by the pressure relief valve 64, then the gaseous carbon dioxide is changed into liquid state through the second condensing device 7, and is recovered into the liquid carbon dioxide storage tank 1. The carbon dioxide recovered into the storage tank is used for 25 times of decolorization of polyester fabric, and the recycling of the recovered carbon dioxide is completed.

[0054] The K / S value, color intensity deviation, decolorization rate, dye recovery rate, breaking strength and breaking strength loss rate of the present embodiment are consistent with those of the specific embodiment 2.

[0055] According to the above experimental method and calculation procedure, after the supercritical carbon dioxide decolorization cycle and dye collection, the K / S value of the polybutylene terephthalate fabric is reduced from 8.12 to 0.40, the color intensity deviation σ K / S from 0.21 to 0.17, the decolorization rate is 95.10%, the breaking strength loss rate is 9.74%, and the dye recovery rate is 85.24%. In addition, after 25 times of recycling of carbon dioxide, the decolorization efficiency of the polybutylene terephthalate fabric can still reach 95.02%.

[0056] Example 4 Compared with Example 2, the difference is that: S1, 5 kg of polytrimethylene terephthalate fabric (PTT, K / S value after dispersion violet 33 dyeing is 20.02) is wound on the outer wall of the porous distribution pipe 52.

[0057] S2, open the liquid carbon dioxide storage tank 1, and introduce liquid carbon dioxide to make the carbon dioxide flow rate 400 kg / h, which is treated by the first condensing device 2 and then enters the pressurizing pump 3, and is transported to the heat exchanger 4 after being pressurized to 20 MPa, so that the carbon dioxide passing through the heat exchanger 4 is heated to 110℃.

[0058] S3, the polyester fabric to be decolorized is decolorized for 80 min according to the procedure S3 of Example 2.

[0059] S4, after the decolorization is completed, the dye removed in the gradient collection decolorization cycle process is collected according to the procedure S4 of Example 2, with the difference that in the first dye collection tank, the temperature is adjusted to 52℃ by the coil pipe 66, and the pressure is adjusted to 5 MPa by the pressure relief valve 64, so that the supercritical carbon dioxide fluid carrying the dye changes from the supercritical state to the gaseous state, the solubility of the dye in the carbon dioxide is reduced, and then the carried dye is collected through the nano-porous membrane 68, and the processed gaseous carbon dioxide is transported to the second dye collection tank through the gas outlet 63, and the processing procedure is the same as that of the first dye collection tank, the temperature is adjusted to 52℃ by the coil pipe 66, and the pressure is adjusted to 2 MPa by the pressure relief valve 64, and then the gaseous carbon dioxide is changed into liquid state through the second condensing device 7, and is recovered into the liquid carbon dioxide storage tank 1. The carbon dioxide recovered into the storage tank is used for 23 times of decolorization of polyester fabric, and the recycling of the recovered carbon dioxide is completed.

[0060] The K / S value, color intensity deviation, decolorization rate, dye recovery rate, breaking strength and breaking strength loss rate of the present embodiment are consistent with those of the specific embodiment 2.

[0061] According to the above experimental method and calculation procedure, after the supercritical carbon dioxide decolorization cycle and dye collection, the K / S value of the polytrimethylene terephthalate fabric is reduced from the original 20.02 to 0.98, the color intensity deviation σ K / S from the original 0.21 to 0.19, the decolorization rate is 95.10%, the breaking strength loss rate is 9.39%, and the dye recovery rate is 88.87%. In addition, after 23 times of recycling of carbon dioxide, the decolorization efficiency of the polytrimethylene terephthalate fabric can still reach 95.01%.

[0062] Example 5 The present embodiment is compared with Example 2, with the difference that: S1, 5 kg of polyethylene terephthalate and polytrimethylene terephthalate blended fabric (PET / PTT blending ratio is 50 / 50, K / S value after reactive disperse dye (self-made) dyeing is 8.62) is wound on the outer wall of the porous distribution pipe 52.

[0063] S2, open the liquid carbon dioxide storage tank 1, and introduce liquid carbon dioxide to make the carbon dioxide flow rate 200 kg / h, which is treated by the first condensing device 2 and then enters the pressurizing pump 3, and is pressurized to 22 MPa and then transported to the heat exchanger 4, so that the carbon dioxide passing through the heat exchanger 4 is heated to 80℃.

[0064] S3, the polyester fabric to be decolorized is decolorized for 120 min according to the procedure S3 of Example 2.

[0065] S4, after the decolorization is completed, the dye removed in the gradient collection decolorization cycle process is collected according to the step S4 of the embodiment 2, the difference is that the temperature is adjusted to 25 DEG C by the coil pipe 66 and the pressure is adjusted to 4 MPa by the pressure relief valve 64 in the first dye collection tank, so that the supercritical carbon dioxide fluid carrying the dye changes from the supercritical state to the gaseous state, the solubility of the dye in the carbon dioxide is reduced, and then the carried dye is collected through the nano-porous membrane 68, the gaseous carbon dioxide after the treatment is transported to the second dye collection tank through the gas outlet 63, the treatment process is the same as the first dye collection tank, the temperature is adjusted to 25 DEG C by the coil pipe 66, the pressure is adjusted to 1 MPa by the pressure relief valve 64, and then the gaseous carbon dioxide is changed into the liquid state through the second condensing device 7, and is recovered into the liquid carbon dioxide storage tank 1. The carbon dioxide recovered into the storage tank is used for decolorizing 30 polyester fabrics, and the recycling of the recovered carbon dioxide is completed.

[0066] The K / S value, color intensity deviation, decolorization rate, dye recovery rate, breaking strength and breaking strength loss rate of the embodiment are consistent with the specific embodiment 2.

[0067] According to the above experimental method and calculation steps, after the supercritical carbon dioxide decolorization cycle and dye collection, the K / S value of the polyethylene terephthalate and polytrimethylene terephthalate blended fabric (PET / PTT blending ratio 50 / 50) is reduced from 8.62 to 0.27, the color intensity deviation σ K / S from 0.26 to 0.14, the decolorization rate is 96.87%, the breaking strength loss rate is 6.52%, and the dye recovery rate is 90.11%. In addition, after the recycling of the carbon dioxide for 30 times, the decolorization efficiency of the polyethylene terephthalate and polytrimethylene terephthalate blended fabric (PET / PBT blending ratio 50 / 50) can still reach 95.47%.

[0068] Embodiment 6 Compared with the embodiment 2, the difference is that: S1, 3 kg of polyethylene terephthalate and polybutylene terephthalate blended fabric (PET / PBT blending ratio 50 / 50, K / S value of mordant dyeing is 9.51) is wound on the outer wall of the porous distribution pipe 52.

[0069] S2, open the liquid carbon dioxide storage tank 1, and introduce the liquid carbon dioxide to make the carbon dioxide flow rate 100 kg / h, which is treated by the first condensing device 2 and then enters the pressurizing pump 3, and is transported to the heat exchanger 4 after being pressurized to 20 MPa, so that the carbon dioxide passing through the heat exchanger 4 is heated to 90 DEG C.

[0070] S3, the polyester fabric to be decolorized is decolorized for 90 min according to the step S3 of the embodiment 2.

[0071] S4, after the decolorization is completed, the dyes removed in the gradient collection decolorization cycle process are collected according to the step S4 of the embodiment 2, the difference is that in the first dye collection tank, the temperature is adjusted to 46℃ by the coil pipe 66, and the pressure is adjusted to 6 MPa by the pressure relief valve 64, so that the supercritical carbon dioxide fluid carrying the dyes changes from a supercritical state to a gaseous state, the solubility of the dyes in the carbon dioxide is reduced, and then the carried dyes are collected through the nano-porous membrane 68, and the gaseous carbon dioxide after treatment is transported to the second dye collection tank through the gas outlet 63, and the treatment process is the same as that of the first dye collection tank, the temperature is adjusted to 46℃ by the coil pipe 66, and the pressure is adjusted to 3 MPa by the pressure relief valve 64, and then the gaseous carbon dioxide is changed into a liquid state through the second condensing device 7, and is recovered into the liquid carbon dioxide storage tank 1. The carbon dioxide recovered into the storage tank is used for 22 times of decolorization of polyester fabrics, and the recycling of the recovered carbon dioxide is completed.

[0072] The K / S value, color intensity deviation, decolorization rate, dye recovery rate, breaking strength and breaking strength loss rate of the embodiment are consistent with those of the specific embodiment 2.

[0073] According to the above experimental method and calculation steps, after the supercritical carbon dioxide decolorization cycle and dye collection, the K / S value of the polyethylene terephthalate and polybutylene terephthalate blended fabric (PET / PBT blending ratio is 50 / 50) is reduced from 9.51 to 0.47, the color intensity deviation σ K / S from 0.22 to 0.12, the decolorization rate is 95.06%, the breaking strength loss rate is 7.38%, and the dye recovery rate is 85.23%. In addition, after 22 times of recycling of carbon dioxide, the decolorization efficiency of the polyethylene terephthalate and polybutylene terephthalate blended fabric (PET / PBT blending ratio is 50 / 50) can still reach 95.02%.

[0074] Example 7 Compared with the embodiment 2, the difference is that: S1, 5 kg of polybutylene terephthalate and polytrimethylene terephthalate blended fabric (PBT / PTT blending ratio is 50 / 50, and the K / S value of the biomass-derived natural dye (turmeric) after dyeing is 8.33) is wound on the outer wall of the porous distribution pipe 52.

[0075] S2, open the liquid carbon dioxide storage tank 1, and introduce liquid carbon dioxide to make the carbon dioxide flow rate 350 kg / h, which is treated by the first condensing device 2 and then enters the pressurizing pump 3, and is pressurized to 25 MPa and then transported to the heat exchanger 4, so that the carbon dioxide passing through the heat exchanger 4 is heated to 70℃.

[0076] S3, decoloring the polyester fabric to be decolored according to the procedure S3 of Example 2 for 60 min.

[0077] S4, after the completion of the decoloring, collecting the dyes removed in the decoloring cycle according to the procedure S4 of Example 2, with the difference that in the first dye collection tank, the temperature is adjusted to 25°C by means of the coil 66 and the pressure is adjusted to 8 MPa by means of the pressure relief valve 64, so as to change the supercritical carbon dioxide fluid carrying the dyes from the supercritical state to the gaseous state, to reduce the solubility of the dyes in carbon dioxide, and then collect the dyes carried by means of the nano-porous membrane 68, and the gaseous carbon dioxide treated is delivered to the second dye collection tank through the gas outlet 63, and the treatment process is the same as that of the first dye collection tank, the temperature is adjusted to 25°C by means of the coil 66 and the pressure is adjusted to 4 MPa by means of the pressure relief valve 64, and then the gaseous carbon dioxide is changed into liquid state by means of the second condensing device 7, and is recovered into the liquid carbon dioxide storage tank 1. The carbon dioxide recovered into the storage tank is used for 20 times of decoloring of the polyester fabric, and the recycling of the carbon dioxide is completed.

[0078] The K / S value, the color intensity deviation, the decoloring rate, the dye recovery rate, the breaking strength and the breaking strength loss rate of the present embodiment are consistent with those of the specific embodiment 2.

[0079] According to the above experimental method and calculation procedure, after the supercritical carbon dioxide decoloring cycle and dye collection, the K / S value of the polybutylene terephthalate and polytrimethylene terephthalate blended fabric (PBT / PTT blending ratio 50 / 50) is reduced from the original 8.33 to 0.12, the color intensity deviation σ K / S from the original 0.31 to 0.17, the decoloring rate is 98.56%, the breaking strength loss rate is 4.66%, and the dye recovery rate is 91.28%. In addition, after the recycling of carbon dioxide for 20 times, the decoloring efficiency of the polybutylene terephthalate and polytrimethylene terephthalate blended fabric (PBT / PTT blending ratio 50 / 50) can still reach 97.74%.

[0080] The above-described embodiments only express several embodiments of the present application, which are described in a more specific and detailed manner, but should not be understood as limiting the scope of the patent application. It should be noted that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, which are all within the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A supercritical carbon dioxide anhydrous decolorization system for polyester fabrics, characterized in that, The system includes a liquid carbon dioxide storage tank (1), a first condensing device (2), a pressurizing pump (3), a heat exchanger (4), a decolorizing reactor (5), at least one dye collection vessel (6), and a second condensing device (7). The liquid carbon dioxide storage tank (1), the first condensing device (2), the pressurizing pump (3), the heat exchanger (4), the decolorizing reactor (5), the dye collection reactor (6), and the second condensing device (7) are connected in sequence by pipelines to form a circulation loop; The decolorization reactor (5) includes an outer sleeve (51), a porous distribution tube (52), and an inner porous sleeve (53); the inner porous sleeve (53) is located inside the porous distribution tube (52), and the porous distribution tube (52) is located inside the outer sleeve (51); The outer sleeve (51) has a gas inlet (511) at the bottom and a gas outlet (512) at the top; the inner porous sleeve (53) has a first gas guide channel (531) and a second gas guide channel (532). One end of the gas inlet (511) is connected to the heat exchanger (4), and the other end of the gas inlet (511) is connected to the inner porous sleeve (53) through the first gas guide channel (531). One end of the gas outlet (512) is connected to the inner porous sleeve (53) through the second gas guide channel (532), and the other end of the gas outlet (512) is connected to the dye collection vessel (6). The first gas guide channel (531) is used to provide a path for carbon dioxide fluid to enter the inner porous sleeve (53) through the gas inlet (511), and the second gas guide channel (532) is used to provide a path for carbon dioxide fluid to enter the dye collection vessel (6) through the gas outlet (512). The inner porous sleeve (53) is provided with through holes distributed along its circumference; the porous distribution tube (52) is provided with through holes (521) distributed along its circumference. The dye collection vessel (6) includes a vessel body (61), a fluid inlet (62) with a throttle valve (67) on the top side of the vessel body (61), and a gas outlet (63) with a nanoporous membrane (68) on the bottom side of the vessel body (61); a pressure relief valve (64) is also provided at the bottom of the vessel body (61), as well as a frame (65) located at the top of the vessel body (61) and a coil (66) located inside the vessel body (61).

2. The supercritical carbon dioxide anhydrous decolorization system for polyester fabrics according to claim 1, characterized in that, The diameter of the through hole structure of the inner porous sleeve (53) is 5~8 mm, and the diameter of the inner porous sleeve (53) is 55 mm.

3. The supercritical carbon dioxide anhydrous decolorization system for polyester fabrics according to claim 1, characterized in that, The diameter of the through hole (521) of the porous distribution tube (52) is 5~8mm; The diameter of the porous distribution tube (52) is 60 mm.

4. The supercritical carbon dioxide anhydrous decolorization system for polyester fabrics according to claim 3, characterized in that, The through hole (521) is composed of a through hole structure with the hole diameter arranged in a gradient cycle.

5. The supercritical carbon dioxide anhydrous decolorization system for polyester fabrics according to claim 1, characterized in that, The number of dye collection vessels (6) is 2 to 4; The first condensing device (2) includes a first condenser (21) and a first refrigeration compressor (22); The second condensing device (7) includes a second condenser (71) and a second refrigeration compressor (72).

6. The supercritical carbon dioxide anhydrous decolorization system for polyester fabrics according to claim 1, characterized in that, The nanoporous membrane (68) includes a ceramic membrane or a polymer ultrafiltration membrane with a pore size of 1~10 nm.

7. A method for supercritical carbon dioxide anhydrous decolorization of polyester fabrics, characterized in that, The decolorization system according to any one of claims 1-6 specifically includes the following steps: S1. Wrap the polyester fabric to be decolored around the outer wall of the porous distribution tube (52); S2. The liquid carbon dioxide in the liquid carbon dioxide storage tank (1) is processed by the first condensing device (2) and then enters the pressurizing pump (3). The pressurization exceeds the critical pressure of carbon dioxide and is delivered to the heat exchanger (4), so that the carbon dioxide passing through the heat exchanger (4) is heated to a temperature exceeding the supercritical temperature. S3. The supercritical carbon dioxide discharged through the heat exchanger (4) is transported to the decolorization reactor (5) and injected through the gas inlet (511) at the bottom of the outer sleeve (51). It enters the flow channel of the inner porous sleeve (53) through the first gas guide channel (531), and then penetrates the through hole structure of the inner porous sleeve (53) and the through hole (521) of the porous distribution pipe (52) to uniformly contact the polyester fabric to be decolorized, and conduct high-density directional penetration on the polyester fabric to be decolorized, so as to decolorize the polyester fabric to be decolorized. S4. After decolorization, the supercritical carbon dioxide fluid carrying the dye is transported through the second gas channel (532) to at least one dye collection vessel (6) through the gas outlet (512) at the top of the outer sleeve (51). After depressurization by a throttle valve (67), it enters the vessel body (61) of the dye collection vessel (6) through the fluid inlet (62). The temperature is adjusted to the dye collection temperature by the coil (66), and the pressure is adjusted to the dye collection pressure by the pressure relief valve (64) to change the supercritical carbon dioxide fluid carrying the dye from the supercritical state to the gaseous state. Then, the dye is collected through the nanoporous membrane (68). The treated gaseous carbon dioxide is transported through the gas outlet (63) to the second condenser (7) for further processing to turn the gaseous carbon dioxide into liquid and recover it into the liquid carbon dioxide storage tank (1).

8. The supercritical carbon dioxide anhydrous decolorization method for polyester fabrics according to claim 7, characterized in that, In step S2, the flow rate of the liquid carbon dioxide is 100~400 kg / h; In step S2, the pressurization pressure of the pressurizing pump (3) is controlled at 8~30MPa, and the heating temperature of the heat exchanger (4) is controlled at 70~130℃. In step S3, the decolorization time is 10~120 min; In step S4, the dye collection temperature is 20~60℃ and the dye collection pressure is 1~8MPa.

9. The supercritical carbon dioxide anhydrous decolorization method for polyester fabrics according to claim 7, characterized in that, In step S4, when the dye collection vessel (6) is a multi-stage dye collection vessel (6) consisting of 2 to 4 vessels, the dye collection pressure set for each dye collection vessel (6) decreases in a gradient according to their arrangement order.

10. The supercritical carbon dioxide anhydrous decolorization method for polyester fabrics according to claim 7, characterized in that, The polyester fabric to be decolorized includes one or more blended or composite coated fabrics of polyethylene terephthalate fabric, polybutylene terephthalate fabric, and polypropylene terephthalate fabric. The dyes include at least one of disperse dyes, reactive disperse dyes, mordant dyes, and biomass-derived natural dyes.

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