CN115197467A - Method for separating polyester and cotton in blended fabric - Google Patents

Method for separating polyester and cotton in blended fabric Download PDF

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Publication number
CN115197467A
CN115197467A CN202110393165.XA CN202110393165A CN115197467A CN 115197467 A CN115197467 A CN 115197467A CN 202110393165 A CN202110393165 A CN 202110393165A CN 115197467 A CN115197467 A CN 115197467A
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pet
tempo
cotton
oxidase
concentration
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葛仪文
姚磊
陈学聪
潘颂恩
陈虹
张晗蓉
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Hong Kong Research Institute of Textiles and Apparel Ltd
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Hong Kong Research Institute of Textiles and Apparel Ltd
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Priority to CN202110393165.XA priority Critical patent/CN115197467A/en
Priority to PCT/CN2021/099804 priority patent/WO2022217735A1/en
Publication of CN115197467A publication Critical patent/CN115197467A/en
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J11/00—Recovery or working-up of waste materials
    • C08J11/04—Recovery or working-up of waste materials of polymers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
    • C08L1/02—Cellulose; Modified cellulose
    • C08L1/04—Oxycellulose; Hydrocellulose, e.g. microcrystalline cellulose
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
    • C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2301/00—Characterised by the use of cellulose, modified cellulose or cellulose derivatives
    • C08J2301/04—Oxycellulose; Hydrocellulose
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
    • C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/62—Plastics recycling; Rubber recycling

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Preparation Of Compounds By Using Micro-Organisms (AREA)
  • Enzymes And Modification Thereof (AREA)

Abstract

The present disclosure provides for the separation of cotton and PET in PET-cotton blends by oxidizing the cotton by chemical (hydrogen peroxide) and biological (oxidase) methods while retaining the PET. The method provides a green, nontoxic and energy-saving treatment method for the cotton/PET blended fabric.

Description

Method for separating polyester and cotton in blended fabric
Technical Field
The present disclosure relates to a method of separating polyester (polyethylene terephthalate (PET)) and cotton from a hybrid textile. More particularly, the disclosure relates to a method of separating PET and cotton phases of a blended fabric by an oxidation reaction.
Background
Textile waste disposal is a significant problem, leading to environmental problems in landfills and incineration, with negative consequences. In addition, blend fabric waste presents challenges in recycling due to the differences in the physical and chemical properties of the fibers.
To address this problem, several methods of PET and cotton separation have been developed by selectively dissolving or degrading one of PET and cotton to effect separation and reuse of the selected PET or cotton. These methods include the dissolution of cotton by (i) degradation with acid or microorganisms, or (ii) dissolution of cotton with ionic liquids or N-methylmorpholine N-oxide, which is expensive. Also proposed is a process for depolymerizing polyester by retaining cotton using hydrolysis and alcoholysis of the polyester. In the existing separation methods of PET-cotton mixed fabrics, cellulose and PET cannot be simultaneously retained.
The green separation method for PET-cotton mixtures is very limited. Existing recycling or reuse methods may require organic/ionic solvents, high temperatures, or high costs. Moreover, the above method has little effect on recycled materials by changing its inherent characteristics.
Disclosure of Invention
It is therefore an object of the present disclosure to provide a process for the preparation of a catalyst by chemical oxidation (based on H) 2 O 2 Oxidation) and oxidation of oxidase (laccase) to separate cotton from PET in PET-cotton blend fabrics.
In a first aspect, provided herein is an H-based 2 O 2 In the presence of H as an oxidizing agent 2 O 2 And 2,2,6,6-tetramethylpiperidine-nitrogen-oxide (TEMPO) as a catalyst, cotton is subjected to oxidation to convert cotton fibers to cotton dust, while PET remains in fiber form during this process.
The method for separating PET from cotton in the PET-cotton blended fabric comprises the following steps: contacting the blended fabric with hydrogen peroxide or an oxidase in the presence of TEMPO; the method in which hydrogen peroxide is contacted is called a hydrogen peroxide method, and the method in which an oxidase (e.g., laccase) is contacted is called an oxidase method.
According to some embodiments, in the hydrogen peroxide process, the PET-cotton blend fabric is mixed with hydrogen peroxide (H) at a concentration of 1% to 10% (v/H2O v) 2 O 2 ) Stirring at a temperature of 55 ℃ to 65 ℃ and a pH of 8 to 10 in the presence of TEMPO at a concentration of 0.1% to 5.0% (w/v), wherein the liquid ratio of the reaction system is 1:50 to 1:300 and the reaction time is 6 to 48 hours.
According to some embodiments, the concentration of hydrogen peroxide is 8% to 10%. According to some embodiments, the concentration of hydrogen peroxide is 10%.
According to some embodiments, the concentration of TEMPO is 0.5% to 2.0% (w/v). According to some embodiments, the concentration of TEMPO is 0.8% to 1.5% (w/v). According to some embodiments, the concentration of TEMPO is 0.1% to 1.0% (w/v). According to some embodiments, the concentration of TEMPO is 1.0% (w/v)
According to some embodiments, the pH of the reaction system is from 8 to 10. According to some embodiments, the pH of the reaction system is 9 to 10. According to some embodiments, the reaction system has a pH of 10.
According to some embodiments, the reaction time is 6 to 30 hours. According to some embodiments, the reaction time is 6 to 24 hours. According to some embodiments, the reaction time is 24 hours.
According to some embodiments, the reaction temperature is 60 to 65 ℃. According to some embodiments, the reaction temperature is 65 ℃.
According to some embodiments, the liquid ratio of the reaction system is 1:75 to 1:250. according to some embodiments, the liquid ratio of the reaction system is 1:100 to 1:200. according to some embodiments, the liquid ratio of the reaction system is 1:100 to 1:150. according to some embodiments, the liquid ratio of the reaction system is 1:100.
according to some embodiments, in the oxidase process, the PET-cotton blend fabric is incubated with an oxidase (e.g. laccase) at a concentration of 0.5 to 55mg/mL, TEMPO at a concentration of 3.75mg/mL to 60mg/mL, the enzyme is operated at a temperature of 20 ℃ to 60 ℃, pH in the range of 3 to 6, and the liquid ratio of the reaction system is 1:50 to 1:300 and the reaction time is 2 to 72 hours.
According to some embodiments, the weight ratio of oxidase to TEMPO is 0.5-8:1. according to some embodiments, the weight ratio of oxidase to TEMPO is 1-4:1. according to some embodiments, the weight ratio of oxidase to TEMPO is 1-3:1. according to some embodiments, the weight ratio of oxidase to TEMPO is 2:1.
according to some embodiments, the oxidase is a laccase.
According to some embodiments, the concentration of oxidase is 25 to 50mg/mL. According to some embodiments, the concentration of oxidase is 30 to 45mg/mL. According to some embodiments, the concentration of oxidase is 30 to 40mg/mL. According to some embodiments, the concentration of oxidase is 30mg/mL.
According to some embodiments, the concentration of TEMPO is from 7.5 to 30mg/mL. According to some embodiments, the concentration of TEMPO is from 10 to 22.5mg/mL. According to some embodiments, the concentration of TEMPO is 15mg/mL.
According to some embodiments, the working temperature of the oxidase is from 40 ℃ to 60 ℃. According to some embodiments, the oxidase is operated at a temperature of 40 ℃ to 55 ℃. According to some embodiments, the working temperature of the oxidase is from 40 ℃ to 50 ℃.
According to some embodiments, the oxidase enzyme has a working pH of 3 to 4. According to some embodiments, the oxidase enzyme has a working pH of 4 to 5. According to some embodiments, the oxidase has a working pH of 4 to 4.5. According to some embodiments, the oxidase enzyme has a working pH of 4.
According to some embodiments, in the oxidase method, the liquid ratio of the reaction system is 1:50-1:250. according to some embodiments, in the oxidase method, the liquid ratio of the reaction system is 1:100-1:200. according to some embodiments, in the oxidase method, the liquid ratio of the reaction system is 1:100-1:150. according to some embodiments, in the oxidase method, the liquid ratio of the reaction system is 1:100.
according to some embodiments, the reaction time of the oxidase process is 5 to 50 hours. According to some embodiments, the reaction time of the oxidase process is 8 to 48 hours. According to some embodiments, the reaction time of the oxidase process is 8 to 36 hours. According to some embodiments, the reaction time of the oxidase process is 36 hours. According to some embodiments, the reaction time of the oxidase process is 8 hours.
In some embodiments, H is studied by a gradient from 1% to 10% (v/H2O v) 2 O 2 The effect of concentration. In the reaction, H 2 O 2 Decompose and generate a hydroxyl radical which attacks carbon atoms on the cellulose, resulting in the hydroxyl radical forming a carboxyl group. Thus, the cellulose fibers are cut intoCellulose powder for separation.
In some embodiments, H 2 O 2 The oxidation capacity of TEMPO was catalyzed by TEMPO, the catalytic action of TEMPO was studied by varying its concentration from 0.1% to 5.0% (w/H2O v).
In some embodiments, the effect of temperature on separation efficiency was studied by changing the reaction temperature from 55 ℃ to 65 ℃.
In some embodiments, due to pH and H 2 O 2 Is highly relevant, so the pH effect is illustrated by changing the reaction from pH8 to pH 10.
In some embodiments, the separation efficiency versus reaction time is studied.
In some embodiments, the liquid ratio is from 1:50 to 1:200 to verify reaction behavior and separation performance.
In some embodiments, the cotton dust and PET fibers are separated by simple filtration, then washed and dried. Separation efficiency is defined as the weight percentage of the collected separated product (cotton or PET) to the cotton or PET in the original textile.
In some embodiments, the separated cotton and PET are further characterized and characterized by FTIR and SEM to show the quality and purity of the product.
The oxidase process provided herein can utilize a laccase/TEMPO system. Briefly, laccase from Aspergillus was selected to perform the method. In the presence of the catalyst TEMPO, the laccase acts as an oxidizing agent to selectively oxidize the cellulose fibers to cellulose powder. The presence of oxygen in the air causes the oxidation of laccase, followed by the oxidation of TEMPO and hydroxyl groups on the cellulose, to form a cellulose powder, while PET is still present in the form of fibers.
In some embodiments, the concentration of laccase varies from 0.5 to 45mg/mL.
In some embodiments, the laccase is present in an amount of from 0.5 to 8:1 (wt/wt) to demonstrate the effect of TEMPO catalytic ability.
In some embodiments, oxidation by an oxidase enzyme studies the effect of reaction temperature by a change from room temperature to 55 ℃.
In some embodiments, the reaction time is monitored from 4 hours to 3 days to indicate the degree of separation.
In some embodiments, the pH of the reaction was varied between 4 and 6 to examine the effect of pH.
In some embodiments, the liquid ratio varies from 1:200 to investigate reaction behavior and separation performance.
In some embodiments, the cotton dust and PET fibers are separated by simple filtration, then washed and dried. Separation efficiency is defined as the weight percentage of the collected separated product (cotton or PET) and the cotton or PET in the raw textile.
In some embodiments, the separated cotton and PET are further characterized and characterized by FTIR and SEM to show the quality and purity of the product.
With PET/cotton =52:48 (wt/wt) textiles were used as test samples.
Drawings
The present disclosure is described in detail below with reference to the accompanying drawings.
FIG. 1 shows the results obtained in the hydrogen peroxide method at a ratio of 0.1% TEMPO (w/H2O v), pH 10, 55 ℃, liquid ratio 1:100. under the reaction conditions of 24 hours, H 2 O 2 The relationship between concentration and separation efficiency.
FIG. 2 shows the hydrogen peroxide method, at 55 ℃, 10% H 2 O 2 (v/H2O v), 1:100, 0.1% TEMPO (w/H2O v), pH and reaction time on the separation.
FIG. 3 shows the% H at pH8, 10% in the hydrogen peroxide method 2 O 2 (v/H2O v), 1% TEMPO (w/H2O v), liquid ratio of 1:100. effect of temperature on separation under 24h reaction conditions.
FIG. 4 shows the% H at pH8, 55 ℃ in the hydrogen peroxide method 2 O 2 (v/H2O v), liquid ratio 1:100. relationship between TEMPO concentration and separation efficiency under 24-hour reaction conditions.
FIG. 5 shows the 10% consumption at pH8, 65 ℃ for 24 hours 2 O 2 And 1%The effect of TEMPO on the liquid ratio on the separation efficiency.
Fig. 6A shows a photograph and SEM image of fibers (PET) and powder (cellulose) separated in the hydrogen peroxide process.
Fig. 6B schematically shows Fourier Transform Infrared (FTIR) spectra of separated fibers and powders in the hydrogen peroxide process, and a comparison with spectra of their raw materials.
FIG. 7 shows laccase activity at pH 4 at 40 ℃ in an oxidation reaction: TEMPO =1:1 (wt/wt), liquid ratio of 1:200, effect of laccase concentration on the separation in an oxidation reaction carried out for 72 hours.
FIG. 8 shows the catalytic effect of TEMPO in laccase oxidation systems, where the laccase concentration was kept at 30mg/mL and the laccase was maintained at optimal concentration for 8 hours at 40 deg.C, pH 4.
FIG. 9 shows the ratio between laccase and TEMPO is 2:1 (wt/wt), 40 ℃, pH 4 for 72h, influence of temperature on laccase oxidation system.
FIG. 10 shows the reaction time of laccase oxidation system as a function of separation efficiency, which was monitored under optimal conditions for 2 to 48 hours.
FIG. 11 shows the pH effect (pH 4 to 6) in the oxidase separation.
FIG. 12 shows the relationship between the liquid ratio and the separation efficiency in the oxidase method.
Fig. 13A shows a photograph and SEM image of fibers (PET) and powder (cellulose) separated by an oxidase method.
FIG. 13B illustrates Fourier Transform Infrared (FTIR) spectra of fibers and powders separated by an oxidase process and compared to spectra of their starting materials.
Detailed Description
The scope of the present disclosure is not limited by any of the specific embodiments described herein. The following embodiments are described by way of example only.
The separation process of the present disclosure was developed for the separation of PET-cotton blends. It involves two mentioned mechanisms, including a hydrogen peroxide method system and an oxidase method system, to slightly change the cellulose fibers into cellulose powder, achieve green separation by simple filtration and recover these materials.
In the present disclosure, the two separation methods described above have great potential, they separate PET-cotton blends in different proportions by these pretreatment-free and selection-free methods.
Both the hydrogen peroxide process and the oxidase process mentioned involve the oxidation of cellulose in the presence of the catalyst TEMPO to produce short cellulose fibres. Thus, the long PET fibers can be separated from the short cotton fibers by simple filtration.
These separation methods are not limited to the ratio of cotton to PET and the web of any ratio of these two materials is converted to cellulose powder and PET fibers by the above-described methods.
In the hydrogen peroxide process, the cotton-PET blend is simply placed in H 2 O 2 TEMPO solution, then under mild heating and stirring to start the oxidation reaction of the cotton. H 2 O 2 The color of the TEMPO solution changes from orange to colorless, indicating the completion of the reaction.
H 2 O 2 Plays an important role in controlling the separation efficiency. As shown in fig. 1, with H 2 O 2 The separation efficiency increases with increasing concentration (especially from 8% to 10%). Due to the high concentration of H 2 O 2 In the presence of 10% H 2 O 2 Complete separation can be achieved.
In the separation by the hydrogen peroxide method, the pH also influences H 2 O 2 Decomposition of (3). As shown in fig. 2, the decomposition at pH 10 was consistently better than pH 9 and pH8 by comparing the overall performance of the separation system at different pH conditions. H 2 O 2 The decomposition of (c) is pH dependent, with higher pH decomposing faster. Therefore, higher pH favors the reaction.
As shown in figure 2, the optimum reaction time for the hydrogen peroxide separation is 24h, and the fabric can be completely separated.
The effect of temperature on the separation efficiency of the hydrogen peroxide process is that the separation efficiency increases with temperature. As shown in fig. 3, the temperature was increased from 55 ℃ to 65 ℃ and TEMPO increased from 0.1% to 1% so that separation occurred at pH8 (a more neutral environment) when more energy was provided to initiate the oxidation reaction. Furthermore, the increase in TEMPO, i.e. free radicals, also catalyzes the oxidation reaction. In the presence of hydrogen peroxide, TEMPO is first transferred to the nitro cation and then hydroxylamine is formed. TEMPO goes through its reaction cycle and continues to induce H2O2 decomposition. The optimum reaction temperature is 65 ℃.
The role of TEMPO in the hydrogen peroxide process is clear. As shown in fig. 4, the presence of TEMPO increased the separation efficiency from 0.1% to 1%, however, excess TEMPO inhibited the separation by the hydrogen peroxide process.
The liquid ratio, i.e. the ratio of fabric weight/solvent (e.g. water) weight, is optimized for the hydrogen peroxide process to have maximum reactivity and minimum cost. As shown in fig. 5, for less than 1: the liquid ratio of 100, due to the 50% reduction in separation efficiency, is apparently insufficient for the solvent. And the sample was mixed in solution at a ratio of 1:100 and 1: the separation efficiency remained 100% when the solution of 200 was incubated. Therefore, a liquid ratio of 1:100, which maintains high separation efficiency and minimizes solvent (separating agent) consumption.
The microscopic image was captured by SEM, and in the case of pH8, the damage to the PET fiber was small, showing that the excellent properties of the original PET fiber were maintained. The separated cellulose powder and PET fibers were characterized by SEM. After the oxidation reaction, the surface PET fibers remained smooth, while the cotton became short cellulose chips. As shown in fig. 6A.
The separated cellulose powder and PET were identified by FTIR. The isolated fiber was identified as pure PET and the isolated powder was identified as pure cotton, as shown in fig. 6B.
In the oxidase process, the biological enzyme laccase is applied to the chemical enzyme modification of cellulose. In the presence of TEMPO as a mediating substance, cellulose fibres are oxidized under mild aqueous conditions to small cellulose powders. In this aerobic reaction, laccase induces TEMPO oxidation, and the oxidized TEMPO reacts with the cellulose. At the same time, TEMPO + is continuously regenerated by reaction with laccase, and therefore the C6 s on the cellulose continue to be oxidized until all the cellulose is oxidized, forming a cellulose powder. While the PET fibers remained unchanged in the reaction of the oxidase.
The concentration of laccase was first optimized by varying the concentration from 0.5mg/mL to 45mg/mL. As shown in FIG. 7, the separation efficiency increased significantly with increasing laccase concentration until the concentration reached 30mg/mL. Indicating that laccase concentration is one of the key factors for the separation by the oxidase method. 30mg/mL laccase was the optimal concentration for the reaction.
The weight ratio of laccase to TEMPO also has an effect on the separation efficiency. As shown in fig. 8, a small change in the ratio has a large influence on the separation performance in the oxidase-based separation. The preferred weight ratio of laccase to TEMPO is 2:1, the separation efficiency of a 30mg/mL laccase solution is further improved, and the complete separation of a cotton/PET mixture is promoted.
As shown in fig. 9, the operating temperature range of the oxidase was 40 ℃ to 55 ℃ showing the consistency of the separation efficiency. Temperatures of 40 ℃ to 50 ℃ are considered to be the optimum reaction temperature for the separation system, matching the properties of the laccase, in the temperature range where the enzyme activity is highest.
For the oxidase reaction, lowering the temperature from 40 ℃ to room temperature, the laccase activity is low and additional reaction time is required to complete the separation.
The separation by the oxidase process was monitored and as shown in figure 10, complete separation was found at 8h, indicating that the process can achieve rapid separation.
The pH affects the properties of the enzyme (laccase). The present disclosure investigates the effect of pH on the system of oxidases. As shown in fig. 11, between pH 4 and 6, e.g. between pH 4 and 5. The optimum pH is considered to be pH 4, and an increase in pH affects the degree of separation. This may be due to loss of enzyme activity at high pH.
Similar to previous hydrogen peroxide process reactions, the liquid ratio of the oxidase process separation was studied to minimize reagent consumption. As shown in fig. 12, separation efficiency was optimized at different liquid ratios, where the liquid ratio was between 1:200, the optimal liquid ratio is 1:100, complete separation can be achieved with minimal reagent consumption.
The results of SEM imaging and FTIR analysis of the PET and cellulose powders isolated from the oxidase reaction are shown in fig. 13A and 13B, respectively. The results are similar to the hydrogen peroxide method, showing a high degree of consistency of the two reactions.
The success of the hydrogen peroxide separation process is demonstrated by the present disclosure selecting a PET-cotton (52 to 48 weight ratio) blend as an example.
Detailed Description
The separation methods of the present disclosure will be illustrated below without intending any limitation on these separation methods.
Example 1
Hydrogen peroxide process
1kg of TEMPO and 100L of 10% H 2 O 2 Mixed with 1kg of textile to be treated (cotton to PET mixing ratio 52 48), at pH8, 65 ℃, liquor ratio 1: stirring for 24 hours under the condition of 100, then filtering, separating cotton powder from PET fibers, and washing and drying to respectively obtain 0.52kg of PET and 0.48kg of cotton powder. Photographs and SEM images of the separated PET fibers and cotton powder (cellulose) are shown in fig. 6A, and Fourier Transform Infrared (FTIR) spectra and their comparison with spectra of the starting material is shown in fig. 6B.
Example 2
Oxidase method
Mixing 15mg/mL TEMPO and 30mg/mL laccase with 1kg textile to be treated (mix ratio of cotton to PET 52, 48), at 40 ℃, pH 4, liquid ratio 1: stirring for 8h under the condition of 100, filtering, separating cotton powder from PET fiber, washing and drying to obtain 0.52kg of PET and 0.48kg of cotton powder respectively. Photographs and SEM images of the separated PET fibers and cotton powder (cellulose) are shown in fig. 13A, and Fourier Transform Infrared (FTIR) spectra and their comparison with spectra of the raw material is shown in fig. 13B.
Industrial applicability
The process provided by the present disclosure is a rapid, energy efficient, and non-toxic separation process for cotton-PET mixtures. The separated PET still has good performance and can be directly reused in the textile industry, and the cellulose powder is changed into a short fiber form and can be spun into long fibers and filaments for future use.

Claims (10)

  1. A method of separating PET from cotton in a PET-cotton blend fabric, comprising the steps of: in the presence of TEMPO, contacting the blended fabric with hydrogen peroxide or oxidase to perform oxidation reaction; among them, the method of contacting with hydrogen peroxide is called a hydrogen peroxide method, and the method of contacting with an oxidase is called an oxidase method.
  2. 2. The method of claim 1, wherein the oxidase is a laccase.
  3. 3. The process according to claim 1, wherein in the hydrogen peroxide process, the PET-cotton blend fabric is mixed with hydrogen peroxide at a concentration of 1 to 10% by volume in the presence of TEMPO at a concentration of 0.1 to 5.0% by weight and volume at a temperature of 55 to 65 ℃ and a pH of 8 to 10, and the mixture is stirred, wherein the liquid ratio of the reaction system is 1:50 to 1:300 and the reaction time is 6 to 48 hours.
  4. 4. The method according to claim 1 or 3, wherein the concentration of hydrogen peroxide is 8% to 10%; or TEMPO concentration of 0.5% to 2.0%; or a pH of 9 to 10; or the reaction time is 6-24 hours; or the reaction temperature is 60-65 ℃; or the liquid ratio is 1:100 to 1:200.
  5. 5. the method of claim 4, wherein the concentration of hydrogen peroxide is 10%; or TEMPO concentration of 1.0%; or a pH of 10; or the reaction time is 24 hours; or the reaction temperature is 65 ℃; or the liquid ratio is 1:100.
  6. 6. the method according to claim 1 or 2, characterized in that in the oxidase process the PET-cotton blend fabric is incubated with oxidase at a concentration of 0.5 to 55mg/mL, TEMPO at a weight to volume concentration of 3.75 to 60mg/mL, the enzyme working temperature is 20 to 60 ℃, the pH range is 3 to 6, the liquid ratio of the reaction system is 1:50 to 1:300 and the reaction time is 2 to 72 hours.
  7. 7. The method of claim 6, wherein the concentration of the enzyme is 25-50mg/mL; or the working temperature of the enzyme is 40 ℃ to 55 ℃; or the pH of the reaction system is in the range of 4 to 5; or the liquid ratio of the reaction system is 1:100-1:200 of a carrier; or the reaction time is 8 to 48 hours.
  8. 8. The method according to claim 6 or 7, wherein the concentration of the enzyme is 30mg/mL; or the working temperature of the enzyme is 40 ℃ to 50 ℃; or the pH range of the reaction system is 4; or the liquid ratio of the reaction system is 1:100, respectively; or the reaction time was 8 hours.
  9. 9. The method according to any one of claims 1, 2,6 to 8, wherein the weight ratio of enzyme to TEMPO is from 0.5 to 8:1.
  10. 10. the method according to claim 9, characterized in that the weight ratio of enzyme to TEMPO is 2:1.
CN202110393165.XA 2021-04-13 2021-04-13 Method for separating polyester and cotton in blended fabric Pending CN115197467A (en)

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