Recycling method of waste textiles

Abstract

The invention discloses a waste textile recovery method, which belongs to the technical field of resource recovery, and comprises the following steps: 1, disinfecting, decolorizing and crushing waste textiles to obtain pretreated waste textiles; step 2, uniformly mixing citric acid, zinc chloride, polyether-based ionic liquid and deionized water to obtain treatment liquid, adding the pretreated waste textiles into the treatment liquid, and stirring in vacuum to obtain dissociation slurry; step 3, carrying out centrifugal treatment on the dissociation slurry to obtain a cellulose solution and a polyester insoluble substance, stirring the polyester insoluble substance at 120-150 DEG C for 1-7 hours, and then washing and drying to obtain polyester; 4, the cellulose solution is subjected to film laying, solidification, cleaning and drying treatment, and the regenerated cellulose film is obtained.The method is high in treatment energy efficiency, the cotton fibers are selectively dissolved, meanwhile, the integrity of the polyester fibers is kept, secondary utilization of waste is achieved, and energy conservation and environment protection are achieved.

Description

Technical Field

[0001] This invention belongs to the field of resource recycling technology, specifically relating to a method for recycling waste textiles. Background Technology

[0002] Currently, the main methods for disposing of waste clothing are landfilling or incineration, causing serious environmental pollution. Meanwhile, the depletion of petroleum resources severely restricts the future development of the chemical fiber industry, which is based on the petrochemical supply chain, leading to a shortage of raw materials for chemical fibers. Therefore, the effective recycling of textiles can not only reduce pollution from waste textiles and benefit environmental protection, but also reduce the occupation of arable land and decrease dependence on petroleum-based products. This has become a research hotspot in the field of textile materials.

[0003] Textiles can be categorized into pure textiles and blended textiles based on their fiber composition. Pure textiles use fibers of the same composition, primarily pure wool, pure cotton, and polyester fibers. Blended textiles contain two or more different types of fibers. Compared to pure textiles, blended textiles typically possess superior properties, such as adjustability and versatility. Therefore, waste textiles often exist in blended form. Recycling processes for pure textiles are relatively mature, but due to the tightly bound components in blended fabrics, effective separation is difficult, making their recycling particularly important. Among blended fabrics, polyester-cotton blends are the most common. Currently, acid-base hydrolysis, alcoholysis, hydrothermal methods, and enzymatic hydrolysis can all achieve the recycling of waste polyester-cotton blends.

[0004] In the field of waste textile recycling, acid-base hydrolysis has attracted attention due to its relatively simple operation, low energy consumption, and controllable cost. However, the acid and alkali solutions used in this method are highly corrosive, posing significant environmental risks and causing severe damage to fibers, making it difficult to effectively separate the reaction products. While alcoholysis offers milder and non-corrosive reaction conditions, the alcohol solvents used are volatile and flammable, posing significant safety hazards. Bioenzymatic methods also have the advantages of mild reaction and high selectivity, but their reaction conditions are usually harsh and the reaction cycle is long; more importantly, the bottleneck of this technology lies in the difficulty of cultivating efficient, stable, and adaptable bioenzymes. Therefore, developing a novel waste textile recycling technology that is environmentally safe, efficient, operates under mild conditions, and allows for easy product separation has become a critical technical problem that urgently needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a method for recycling waste textiles, so as to solve the problem that the products are not easy to separate in the recycling of polyester-cotton blended textiles in the prior art.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for recycling waste textiles includes the following steps: Step 1: Disinfect, decolorize, and shred the waste textiles to obtain pre-treated waste textiles. Step 2: Mix citric acid, zinc chloride, polyether-based ionic liquid and deionized water evenly to obtain a treatment solution. Add the pretreated waste textiles to the treatment solution and stir under vacuum to obtain a dissociated slurry. Step 3: Centrifuge the dissociated slurry to obtain cellulose solution and polyester insoluble matter. Stir the polyester insoluble matter at 120-150℃ for 1-7 hours, then wash with water and dry to obtain polyester. Step 4: The cellulose solution is coated, coagulated, washed, and dried to obtain a regenerated cellulose membrane.

[0007] Furthermore, the ratio of citric acid, zinc chloride, polyether-based ionic liquid, and deionized water in the treatment solution is 1-3g: 1-3g: 1-3mL: 10mL.

[0008] Furthermore, the ratio of pretreated waste textiles to treatment liquid is 1g:8-15mL.

[0009] Furthermore, the vacuum degree described in step two is 100-1000 Pa.

[0010] Furthermore, in step two, the stirring temperature is 70-95℃ and the time is 0.5-4h.

[0011] Furthermore, the polyether-based ionic liquid terminal hydroxyl polyepoxychloropropane is obtained by reacting with N-methylimidazolium, and the terminal hydroxyl polyepoxychloropropane is obtained by ring-opening polymerization of epichlorohydrin.

[0012] Furthermore, the preparation steps of the polyether-based ionic liquid are as follows: S1. Add 1,2-dichloroethane, ethylene glycol, and boron trifluoride diethyl ether to a flask. Under nitrogen protection, cool to 0°C and add a 1,2-dichloroethane solution of epichlorohydrin dropwise while stirring. After the addition is complete, stir the reaction for 3-5 hours. Then transfer the reaction product to a separatory funnel, wash three times with distilled water, and then transfer it to a distillation flask. Distill under reduced pressure at 70°C and 0.09 MPa for 3 hours to obtain hydroxyl-terminated polyepoxychloropropane. S2. Add hydroxyl-terminated polyepoxychloropropane to toluene, stir for 5-8 min, then add N-methylimidazole, heat to 45-55℃ and stir for 10-12 h, cool to room temperature and add diethyl ether, then transfer the reaction product to a distillation flask, remove toluene by vacuum distillation at 90℃ and 0.1 MPa to obtain a polyether-based ionic liquid.

[0013] Furthermore, the volume ratio of ethylene glycol, boron trifluoride ether, and epichlorohydrin in S1 is 2.8:2:38.5-39.2, and the volume ratio of epichlorohydrin to 1,2-dichloroethane in the 1,2-dichloroethane solution of epichlorohydrin is 1-2:1.

[0014] Furthermore, the ratio of toluene, hydroxyl-terminated polyepoxychloropropane, N-methylimidazole, and diethyl ether in S2 is 50-100 mL: 40 g: 60-65 mL: 50-100 mL.

[0015] Furthermore, the specific steps for disinfection and decolorization are as follows: Immerse waste textiles in hydrogen peroxide or sodium hypochlorite solution, controlling the solid-liquid ratio at 1g:15-25mL, decolorize at 55-70℃ for 15-20min, and then dry at 100-110℃ for 2-6h to complete the disinfection and decolorization steps.

[0016] Furthermore, the particle size of the powder processed is ≤2mm.

[0017] Furthermore, the waste textiles are waste cotton / polyester blended textiles.

[0018] Furthermore, the polyester mentioned in step three is polyethylene terephthalate.

[0019] Furthermore, in step four, coagulation is carried out in deionized water at 20°C.

[0020] Furthermore, in step four, the drying temperature is 110-120℃ and the drying time is 24 hours.

[0021] The beneficial effects of this invention are: 1. This invention provides a method for recycling waste textiles. Using waste cotton / polyester blended textiles as raw materials, a treatment solution composed of citric acid, zinc chloride, polyether-based ionic liquid, and deionized water is used to separate and dissolve cotton fibers in the polyester-cotton blend, yielding recycled polyester products and regenerated cellulose membranes. The method is highly efficient, selectively dissolving cotton fibers while maintaining the integrity of polyester fibers, enabling the secondary utilization of waste. It is energy-saving and environmentally friendly. The treatment solution is mild, avoiding the risk of equipment corrosion and harm to operators caused by strong acids and alkalis. The main solvents of the treatment solution are water and non-volatile, non-flammable ionic liquids, eliminating the risks associated with alcohol solvents.

[0022] 2. The treatment solution of this invention is composed of citric acid, zinc chloride, polyether-based ionic liquid, and deionized water. Its key lies in utilizing the synergistic effect of the polyether-based ionic liquid, zinc chloride, and citric acid. This effectively solves the problem of high slurry viscosity and difficulty in separating polyester and cellulose, leading to low recovery rates, when using a single system to treat waste polyester-cotton blended fabrics. The polyether-based ionic liquid belongs to the imidazole class of ionic liquids and is a good solvent for cellulose. It can effectively break the hydrogen bonds between cellulose molecules using its anions, dissolving cellulose without degradation. However, using it alone results in high slurry viscosity, making it difficult to separate polyester and cellulose, leading to low product recovery rates. Therefore, this invention also introduces zinc chloride and citric acid into the treatment solution. 2+ Citric acid interacts with the hydroxyl oxygen on the electron-pair donor cellulose, sequentially breaking the intermolecular hydrogen bonds of cellulose and promoting the decomposition of the cellulose macromolecular chain. Citric acid, on the other hand, provides a large amount of H+. + Maintaining an acidic environment inhibits the formation of complexes and breaks the glycosidic bonds of cellulose, causing the hydrogen bonds and glycosidic bonds of cellulose macromolecules to break, thereby reducing the viscosity of the dissociated slurry and achieving the purpose of effectively separating the components of waste polyester-cotton blended fabrics. In addition, after centrifugation, polyester, citric acid, zinc chloride, polyether-based ionic liquid and cellulose are separated to form a regenerated cellulose membrane. The flexible ether bonds in the polyether-based ionic liquid help improve the toughness of the regenerated cellulose membrane, while zinc ions can form ionic coordination bonds with the hydroxyl groups in cellulose, and citric acid can bind with cellulose through hydrogen bonding. These interactions help improve the mechanical properties of the regenerated cellulose membrane. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] The waste textiles used in this application are waste cotton / polyester blended textiles, which are recycled from households. The cotton fiber content is 30% and the polyester content is 70%. Unless otherwise specified, the other materials and reagents used can be obtained from commercial sources.

[0025] The following is a detailed description with reference to specific examples.

[0026] Preparation Example 1

[0027] A polyether-based ionic liquid is prepared by the following steps: S1. Add 20 mL of 1,2-dichloroethane, 2.8 mL of ethylene glycol and 2 mL of boron trifluoride diethyl ether to a flask. Under nitrogen protection, cool to 0 °C and add a mixed solution of 38.5 mL of epichlorohydrin and 25 mL of 1,2-dichloroethane dropwise while stirring. After the addition is complete, stir the reaction for 3 h. Then transfer the reaction product to a separatory funnel, wash three times with distilled water, and then transfer it to a distillation flask. Distill under reduced pressure at 70 °C and 0.09 MPa for 3 h to obtain hydroxyl-terminated polyepoxychloropropane. S2. Add 40g of hydroxyl-terminated polyepoxychloropropane to 50mL of toluene, stir for 5min, then add 60mL of N-methylimidazole, heat to 45℃ and stir for 10h, cool to room temperature and add 50mL of diethyl ether, then transfer the reaction product to a distillation flask, remove toluene by vacuum distillation at 90℃ and 0.1MPa to obtain a polyether-based ionic liquid.

[0028] Preparation Example 2

[0029] A polyether-based ionic liquid is prepared by the following steps: S1. Add 20 mL of 1,2-dichloroethane, 2.8 mL of ethylene glycol and 2 mL of boron trifluoride diethyl ether to a flask. Under nitrogen protection, cool to 0 °C and add a mixed solution of 39 mL of epichlorohydrin and 25 mL of 1,2-dichloroethane dropwise while stirring. After the addition is complete, stir the reaction for 4 h. Then transfer the reaction product to a separatory funnel, wash three times with distilled water, and then transfer it to a distillation flask. Distill under reduced pressure at 70 °C and 0.09 MPa for 3 h to obtain hydroxyl-terminated polyepoxychloropropane. S2. Add 40g of hydroxyl-terminated polyepoxychloropropane to 70mL of toluene, stir for 6.5min, then add 62mL of N-methylimidazole, heat to 50℃ and stir for 11h, cool to room temperature and add 80mL of diethyl ether, then transfer the reaction product to a distillation flask, and remove toluene by vacuum distillation at 90℃ and 0.1MPa to obtain a polyether-based ionic liquid.

[0030] Preparation Example 3

[0031] A polyether-based ionic liquid is prepared by the following steps: S1. Add 20 mL of 1,2-dichloroethane, 2.8 mL of ethylene glycol, and 2 mL of boron trifluoride diethyl ether to a flask. Under nitrogen protection, cool to 0 °C and add a mixed solution of 39.2 mL of epichlorohydrin and 25 mL of 1,2-dichloroethane dropwise while stirring. After the addition is complete, stir the reaction for 5 h. Then transfer the reaction product to a separatory funnel, wash three times with distilled water, and then transfer it to a distillation flask. Distill under reduced pressure at 70 °C and 0.09 MPa for 3 h to obtain hydroxyl-terminated polyepoxychloropropane. S2. Add 40g of hydroxyl-terminated polyepoxychloropropane to 100mL of toluene, stir for 8min, then add 65mL of N-methylimidazole, heat to 55℃ and stir for 12h, cool to room temperature and add 100mL of diethyl ether, then transfer the reaction product to a distillation flask, and remove toluene by vacuum distillation at 90℃ and 0.1MPa to obtain a polyether-based ionic liquid.

[0032] Example 1

[0033] A method for recycling waste textiles includes the following steps: Step 1: Disinfect, decolorize, and crush the waste textiles to obtain pre-treated waste textiles with a particle size ≤2mm. Step 2: Mix citric acid, zinc chloride, the polyether-based ionic liquid from Preparation Example 1, and deionized water evenly to obtain a treatment solution. The ratio of citric acid, zinc chloride, polyether-based ionic liquid, and deionized water in the treatment solution is 1g:1g:1mL:10mL. Add pretreated waste textiles to the treatment solution. The ratio of pretreated waste textiles to treatment solution is 1g:8mL. Stir at 70°C under a vacuum of 100Pa for 0.5h to obtain a dissociated slurry. Step 3: Centrifuge the dissociated slurry to obtain a cellulose solution and polyester insoluble matter. Stir the polyester insoluble matter at 120°C for 1 hour, then wash with water and dry to obtain polyester. Step 4: Lay the cellulose solution into a membrane, then soak it in deionized water at 20°C for 2 hours for gelation. After that, take it out and wash it with deionized water. Finally, dry it in an oven at 110°C for 24 hours to obtain a regenerated cellulose membrane with a thickness of 10 μm.

[0034] The specific steps for disinfection and decolorization are as follows: The waste textiles are immersed in hydrogen peroxide or sodium hypochlorite solution, with a solid-liquid ratio of 1g:15mL. The textiles are decolorized at 55℃ for 15 minutes and then dried at 100℃ for 2 hours to complete the disinfection and decolorization steps.

[0035] Example 2

[0036] A method for recycling waste textiles includes the following steps: Step 1: Disinfect, decolorize, and crush the waste textiles to obtain pre-treated waste textiles with a particle size ≤2mm. Step 2: Mix citric acid, zinc chloride, the polyether-based ionic liquid from Preparation Example 1, and deionized water evenly to obtain a treatment solution. The ratio of citric acid, zinc chloride, polyether-based ionic liquid, and deionized water in the treatment solution is 2g:2g:2mL:10mL. Add pretreated waste textiles to the treatment solution. The ratio of pretreated waste textiles to treatment solution is 1g:10mL. Stir at 85°C under a vacuum of 500Pa for 2 hours to obtain a dissociated slurry. Step 3: Centrifuge the dissociated slurry to obtain a cellulose solution and polyester insoluble matter. Stir the polyester insoluble matter at 140°C for 6 hours, then wash with water and dry to obtain polyester. Step 4: Lay the cellulose solution into a membrane with a wet membrane thickness of 100 μm, then soak it in deionized water at 20°C for 2.5 h for gelation, then remove it and wash it with deionized water, and finally dry it in an oven at 115°C for 24 h to obtain a regenerated cellulose membrane with a thickness of 10 μm.

[0037] The specific steps for disinfection and decolorization are as follows: The waste textiles are immersed in hydrogen peroxide or sodium hypochlorite solution, with the solid-liquid ratio controlled at 1g:20mL. The textiles are decolorized at 60℃ for 18min and then dried at 105℃ for 4h to complete the disinfection and decolorization steps.

[0038] Example 3

[0039] A method for recycling waste textiles includes the following steps: Step 1: Disinfect, decolorize, and crush the waste textiles to obtain pre-treated waste textiles with a particle size ≤2mm. Step 2: Mix citric acid, zinc chloride, the polyether-based ionic liquid from Preparation Example 1, and deionized water evenly to obtain a treatment solution. The ratio of citric acid, zinc chloride, polyether-based ionic liquid, and deionized water in the treatment solution is 3g:3g:3mL:10mL. Add pretreated waste textiles to the treatment solution. The ratio of pretreated waste textiles to treatment solution is 1g:15mL. Stir at 95°C for 4 hours under a vacuum of 1000Pa to obtain a dissociated slurry. Step 3: Centrifuge the dissociated slurry to obtain cellulose solution and polyester insoluble matter. Stir the polyester insoluble matter at 150°C for 7 hours, then wash with water and dry to obtain polyester. Step 4: Lay the cellulose solution into a membrane with a wet membrane thickness of 100 μm, then soak it in deionized water at 20°C for 3 hours for gelation, then remove it and wash it with deionized water, and finally dry it in an oven at 120°C for 24 hours to obtain a regenerated cellulose membrane with a thickness of 10 μm.

[0040] The specific steps for disinfection and decolorization are as follows: The waste textiles are immersed in hydrogen peroxide or sodium hypochlorite solution, with a solid-liquid ratio of 1g:25mL. The textiles are decolorized at 70℃ for 20 minutes and then dried at 110℃ for 6 hours to complete the disinfection and decolorization steps.

[0041] Example 4

[0042] A method for recycling waste textiles, based on Example 1, involves replacing the "polyether-based ionic liquid" in Example 1 with an equal mass of the product obtained in Preparation Example 2, while keeping the other raw materials and steps the same as in Example 1.

[0043] Example 5

[0044] A method for recycling waste textiles, based on Example 1, involves replacing the "polyether-based ionic liquid" in Example 1 with an equal mass of the product obtained in Preparation Example 3, while keeping the other raw materials and steps the same as in Example 1.

[0045] Comparative Example 1

[0046] A method for recycling waste textiles, based on Example 1, involves replacing the "polyether-based ionic liquid" in Example 1 with an equal mass of 1-butyl-3-methylimidazolium chloride, while the remaining raw materials and steps are the same as in Example 1.

[0047] Comparative Example 2

[0048] A method for recycling waste textiles, based on Example 1, replaces the "polyether-based ionic liquid" in Example 1 with an equal mass of a mixture of citric acid and zinc chloride in a mass ratio of 1:1, while the remaining raw materials and steps are the same as in Example 1.

[0049] Comparative Example 3

[0050] A method for recycling waste textiles, based on Example 1, involves replacing "citric acid and zinc chloride" in Example 1 with an equal mass of the polyether-based ionic liquid prepared in Example 1, while keeping the other raw materials and steps the same as in Example 1.

[0051] The products obtained by the waste textile recycling methods provided in Examples 1-5 and Comparative Examples 1-3 were tested to calculate the polyester recovery rate and the cellulose recovery rate, where the polyester recovery rate (%) = [Mpet / (M×70%)]×100%, M is the mass of waste cotton / polyester blended textiles, and Mpet is the mass of recycled polyester in g; the tests were conducted using an electronic universal testing machine according to ASTM D882. The samples were made into strips 100 mm long and 10 mm wide, and each group of samples was tested 5 times to calculate the tensile strength and toughness of the regenerated cellulose membrane. The results are shown in Table 1: Table 1

[0052] Analysis of the data recorded in Table 1 shows that the polyester recovery rate in the waste textile recycling method provided by this invention is ≥99.0%, and the tensile strength of the regenerated cellulose membrane is ≥150MPa, and the toughness is ≥302MJ / m. 3 Compared with Comparative Examples 1-3, the recycling method of the present invention has high energy efficiency, selectively dissolves cotton fibers while maintaining the integrity of polyester fibers, realizes the secondary utilization of waste, saves energy and is environmentally friendly. The treatment liquid is mild, avoiding the risk of equipment corrosion and harm to operators caused by strong acids and alkalis. The main solvent of the treatment liquid is water and non-volatile and non-flammable ionic liquids, eliminating the risks brought by alcohol solvents.

[0053] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0054] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for recycling waste textiles, characterized in that, Includes the following steps: Step 1: Disinfect, decolorize, and shred the waste textiles to obtain pre-treated waste textiles. Step 2: Mix citric acid, zinc chloride, polyether-based ionic liquid and deionized water evenly to obtain a treatment solution. Add the pretreated waste textiles to the treatment solution and stir under vacuum to obtain a dissociated slurry. Step 3: Centrifuge the dissociated slurry to obtain cellulose solution and polyester insoluble matter. Stir the polyester insoluble matter at 120-150℃ for 1-7 hours, then wash with water and dry to obtain polyester. Step 4: The cellulose solution is coated, coagulated, washed, and dried to obtain a regenerated cellulose membrane.

2. The method for recycling waste textiles according to claim 1, characterized in that, The ratio of citric acid, zinc chloride, polyether-based ionic liquid, and deionized water in the treatment solution is 1-3g: 1-3g: 1-3mL: 10mL.

3. The method for recycling waste textiles according to claim 1, characterized in that, The ratio of pretreated waste textiles to treatment solution is 1g:8-15mL.

4. The method for recycling waste textiles according to claim 1, characterized in that, The vacuum level described in step two is 100-1000 Pa.

5. The method for recycling waste textiles according to claim 1, characterized in that, In step two, the stirring temperature is 70-95℃ and the time is 0.5-4h.

6. The method for recycling waste textiles according to claim 1, characterized in that, The polyether-based ionic liquid is obtained by reacting hydroxyl-terminated polyepoxychloropropane with N-methylimidazolium, and the hydroxyl-terminated polyepoxychloropropane is obtained by ring-opening polymerization of epichlorohydrin.

7. A method for recycling waste textiles according to claim 1 or 6, characterized in that, The preparation steps of the polyether-based ionic liquid are as follows: S1. Add 1,2-dichloroethane, ethylene glycol, and boron trifluoride diethyl ether to a flask. Under nitrogen protection, cool to 0°C and add a 1,2-dichloroethane solution of epichlorohydrin dropwise while stirring. After the addition is complete, stir the reaction for 3-5 hours. Transfer the reaction product to a separatory funnel, wash three times with distilled water, and then transfer it to a distillation flask. Distill under reduced pressure at 70°C and 0.09 MPa for 3 hours to obtain hydroxyl-terminated polyepoxychloropropane. S2. Add hydroxyl-terminated polyepoxychloropropane to toluene, stir for 5-8 min, then add N-methylimidazole, heat to 45-55℃ and stir for 10-12 h, cool to room temperature and add diethyl ether, transfer the reaction product to a distillation flask, and remove toluene by vacuum distillation at 90℃ and 0.1 MPa to obtain a polyether-based ionic liquid.

8. A method for recycling waste textiles according to claim 7, characterized in that, The volume ratio of ethylene glycol, boron trifluoride ether, and epichlorohydrin in S1 is 2.8:2:38.5-39.2, and the volume ratio of epichlorohydrin to 1,2-dichloroethane in the 1,2-dichloroethane solution of epichlorohydrin is 1-2:

1.

9. A method for recycling waste textiles according to claim 7, characterized in that, In S2, the ratio of toluene, hydroxyl-terminated polyepichlorohydrin, N-methylimidazole, and diethyl ether is 50-100 mL: 40 g: 60-65 mL: 50-100 mL.

10. A method for recycling waste textiles according to claim 1, characterized in that, The specific steps for disinfection and decolorization are as follows: Immerse waste textiles in hydrogen peroxide or sodium hypochlorite solution, controlling the solid-liquid ratio at 1g:15-25mL, decolorize at 55-70℃ for 15-20min, and then dry at 100-110℃ for 2-6h to complete the disinfection and decolorization steps.

Images