WO2022217735A1 - 分离混纺织品中涤纶和棉的方法 - Google Patents

分离混纺织品中涤纶和棉的方法 Download PDF

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WO2022217735A1
WO2022217735A1 PCT/CN2021/099804 CN2021099804W WO2022217735A1 WO 2022217735 A1 WO2022217735 A1 WO 2022217735A1 CN 2021099804 W CN2021099804 W CN 2021099804W WO 2022217735 A1 WO2022217735 A1 WO 2022217735A1
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oxidase
tempo
cotton
pet
concentration
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French (fr)
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WO2022217735A9 (zh
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葛仪文
姚磊
陈学聪
潘颂恩
陈虹
张晗蓉
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香港纺织及成衣研发中心
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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

Definitions

  • the present disclosure relates to a method of separating polyester (polyethylene terephthalate (PET)) and cotton from mixed textiles. More specifically, the present disclosure relates to a method for phase separation of PET and cotton of a blended fabric by an oxidation reaction.
  • PET polyethylene terephthalate
  • Textile waste disposal is a prominent issue, causing environmental problems in landfills and incineration, causing negative impacts. Additionally, blended fabric waste is challenging to recycle due to the different physical and chemical properties of the fibers.
  • Green separation methods for PET-cotton blends are limited. Existing recycling or reuse methods may require organic/ionic solvents, high temperatures, or high costs. Moreover, the above method has little effect on the recycled material by changing its inherent properties.
  • an H2O2 based oxidation process for use in H2O2 as oxidant and 2,2,6,6 - tetramethylpiperidine - nitrogen - oxidation as catalyst
  • Cotton is subjected to oxidation in the presence of PET (TEMPO), turning the cotton fibers into cotton powder, while the PET remains in fiber form during this process.
  • PET PET
  • the method for separating PET and cotton in a PET-cotton blended fabric includes the following steps: in the presence of TEMPO, contacting the blended fabric with hydrogen peroxide or oxidase; wherein the method of contacting with hydrogen peroxide is called Hydrogen peroxide method, the method of contacting with oxidase (eg laccase) is called oxidase method.
  • a PET-cotton blended fabric is mixed with hydrogen peroxide (H 2 O 2 ) at a concentration of 1% to 10% (v/H2O v) at a concentration of 0.1% to 5.0
  • H 2 O 2 hydrogen peroxide
  • % (w/v) TEMPO TEMPO
  • the liquid ratio of the reaction system is 1:50 to 1:300, and the reaction time is 6-48 hours.
  • the concentration of hydrogen peroxide is 8% to 10%. According to some embodiments, the concentration of hydrogen peroxide is 10%.
  • 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)
  • the pH of the reaction system is 8 to 10. According to some embodiments, the pH of the reaction system is 9 to 10. According to some embodiments, the pH of the reaction system is 10.
  • the reaction time is 6-30 hours. According to some embodiments, the reaction time is 6-24 hours. According to some embodiments, the reaction time is 24 hours.
  • the reaction temperature is 60 to 65°C. According to some embodiments, the reaction temperature is 65°C.
  • 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.
  • the PET-cotton blended fabric is incubated with an oxidase (eg, laccase) at a concentration of 0.5 to 55 mg/mL and TEMPO at a concentration of 3.75 mg/mL to 60 mg/mL mL, the working temperature of the enzyme is 20°C to 60°C, 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 2-72 hours.
  • an oxidase eg, laccase
  • 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.
  • the oxidase is a laccase.
  • the concentration of oxidase is 25 to 50 mg/mL. According to some embodiments, the concentration of oxidase is 30 to 45 mg/mL. According to some embodiments, the concentration of oxidase is 30 to 40 mg/mL. According to some embodiments, the concentration of oxidase is 30 mg/mL.
  • the concentration of TEMPO is 7.5 to 30 mg/mL. According to some embodiments, the concentration of TEMPO is 10 to 22.5 mg/mL. According to some embodiments, the concentration of TEMPO is 15 mg/mL.
  • the working temperature of the oxidase is 40°C to 60°C. According to some embodiments, the working temperature of the oxidase is 40°C to 55°C. According to some embodiments, the working temperature of the oxidase is 40°C to 50°C.
  • the working pH of the oxidase is 3 to 4. According to some embodiments, the working pH of the oxidase is 4 to 5. According to some embodiments, the working pH of the oxidase is 4 to 4.5. According to some embodiments, the working pH of the oxidase is 4.
  • 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.
  • the reaction time of the oxidase method is 5 to 50 hours. According to some embodiments, the reaction time of the oxidase method is 8 to 48 hours. According to some embodiments, the reaction time of the oxidase method is 8 to 36 hours. According to some embodiments, the reaction time of the oxidase method is 36 hours. According to some embodiments, the reaction time of the oxidase method is 8 hours.
  • the effect of H 2 O 2 concentration is studied by a gradient from 1% to 10% (v/H 2 O v).
  • H2O2 decomposes and generates a hydroxyl radical, which attacks the carbon atoms on the cellulose, resulting in the formation of a carboxyl group from the hydroxyl group. Therefore, cellulose fibers are cut into cellulose powder for separation purposes.
  • the oxidative power of H2O2 is catalyzed by TEMPO, which was investigated by varying its concentration from 0.1% to 5.0% (w/ H2O v).
  • the effect of temperature on separation efficiency was investigated by changing the reaction temperature from 55°C to 65°C.
  • the pH effect is explained by changing the reaction from pH 8 to pH 10 , since pH is highly correlated with the decomposition rate of H2O2.
  • separation efficiency versus reaction time is studied.
  • the liquid ratio was varied from 1:50 to 1:200 to verify reaction behavior and separation performance.
  • the cotton meal and PET fibers are separated by simple filtration, then washed and dried. Separation efficiency is defined as the weight percent of collected separated product (cotton or PET) to the cotton or PET in the virgin textile.
  • the isolated cotton and PET are further characterized and characterized by FTIR and SEM to show the quality and purity of the product.
  • laccase/TEMPO The oxidase methods provided herein can utilize the laccase/TEMPO system. Briefly, laccases from Aspergillus were selected to carry out the method. In the presence of catalyst TEMPO, laccase acts as an oxidant to selectively oxidize cellulose fibers to cellulose powder. The presence of oxygen in the air causes oxidation of laccase followed by oxidation of TEMPO and hydroxyl groups on cellulose, resulting in the formation of cellulose powder, while PET remains in the form of fibers.
  • the concentration of laccase varies from 0.5 to 45 mg/mL.
  • the effect of TEMPO catalytic ability is demonstrated by a weight ratio of laccase to TEMPO of 0.5 to 8:1 (wt/wt).
  • the effect of reaction temperature is studied by varying from room temperature to 55°C in the oxidation reaction by oxidase.
  • the reaction time is monitored from 4 hours to 3 days to indicate the degree of separation.
  • the pH of the reaction was varied between 4 and 6 to examine the effect of pH.
  • the liquid ratio was varied from 1:50 to 1:200 to investigate reaction behavior and separation performance.
  • the cotton meal and PET fibers are separated by simple filtration, then washed and dried. Separation efficiency is defined as the weight percent of collected separated product (cotton or PET) and cotton or PET in the virgin textile.
  • the isolated cotton and PET are further characterized and characterized by FTIR and SEM to show the quality and purity of the product.
  • the textile with PET/cotton 52:48 (wt/wt) was taken as the test sample.
  • Figure 1 shows the relationship between H 2 O 2 concentration and separation efficiency in the hydrogen peroxide method under the conditions of 0.1% TEMPO (w/H 2 O v), pH 10, 55 °C, liquid ratio 1:100, and 24 hours of reaction. relationship between.
  • FIG. 1 shows the pH and the Effect of reaction time on separation.
  • Figure 3 shows the reaction conditions of pH 8, 10% H 2 O 2 (v/H2O v), 1% TEMPO (w/H2O v), liquid ratio of 1:100, 24h in the hydrogen peroxide method , the effect of temperature on separation.
  • Figure 4 shows the relationship between TEMPO concentration and separation efficiency in the hydrogen peroxide method under the conditions of pH 8, 55°C, 10% H 2 O 2 (v/H2O v), liquid ratio 1:100, and 24 hours of reaction. relationship between.
  • Figure 5 shows the effect of liquid ratio on separation efficiency using 10% H2O2 and 1 % TEMPO for 24 hours at pH 8, 65°C.
  • Figure 6A shows photographs and SEM images of fibers (PET) and powder (cellulose) separated in the hydrogen peroxide method.
  • Figure 6B exemplarily shows the Fourier Transform Infrared (FTIR) spectra of fibers and powders separated in the hydrogen peroxide method, and their spectral comparison with their raw materials.
  • FTIR Fourier Transform Infrared
  • Figure 8 shows the catalytic effect of TEMPO in the laccase oxidation system, in which the concentration of laccase was maintained at 30 mg/mL, and the reaction was maintained at 40 °C and pH 4 for 8 hours to maintain the optimal concentration of laccase.
  • Figure 9 shows the effect of temperature on the laccase oxidation system at a laccase to TEMPO ratio of 2:1 (wt/wt), 40 °C, pH 4 for 72 h.
  • Figure 10 shows the relationship between the reaction time and the separation efficiency of the laccase oxidation system, and the separation efficiency was monitored under optimal conditions from 2 to 48 hours.
  • Figure 11 shows the effect of pH in oxidase separations (pH 4 to 6).
  • Figure 12 shows the relationship between liquid ratio and separation efficiency in the oxidase method.
  • Figure 13A shows photographs and SEM images of oxidase-separated fibers (PET) and powder (cellulose).
  • Figure 13B exemplarily shows Fourier Transform Infrared (FTIR) spectra of oxidase-separated fibers and powders and spectrally compared to their raw materials.
  • FTIR Fourier Transform Infrared
  • the separation method of the present disclosure was developed for the separation of PET-cotton blends. It involves two mentioned mechanisms, including the hydrogen peroxide method system and the oxidase method system, to slightly change the cellulose fibers into cellulose powder, achieve green separation by simple filtration and recover these materials.
  • the two separation methods described above have great potential to separate different proportions of PET-cotton blends by these no-pretreatment and no-selection methods.
  • Both the hydrogen peroxide method and the oxidase method mentioned involve the oxidation of cellulose in the presence of the catalyst TEMPO to produce short cellulose fibers. Therefore, PET long fibers can be separated from short cotton fibers by simple filtration.
  • the cotton-PET blend is simply placed in a H2O2 - TEMPO solution, and then the oxidation reaction of the cotton is initiated with gentle heating and stirring.
  • the color of the H2O2 - TEMPO solution changed from orange to colorless, indicating that the reaction was complete.
  • H2O2 plays an important role in controlling the separation efficiency. As shown in Figure 1 , the separation efficiency increased with increasing H2O2 concentration (especially from 8 % to 10%). Complete separation was achieved when 10 % H2O2 was applied due to the rapid decomposition of high concentrations of H2O2 .
  • pH also affects the decomposition of H2O2.
  • the decomposition of pH 10 was consistently better than that of pH 9 and pH 8.
  • the decomposition of H2O2 is pH dependent, with higher pH decomposing faster. Therefore, higher pH favors the reaction.
  • the optimal reaction time for 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.
  • the temperature was increased from 55°C to 65°C, and the TEMPO was increased from 0.1% to 1%, so that the separation occurred at pH 8 (a more neutral environment), at which time more energy was provided to initiate the oxidation reaction.
  • the increase in TEMPO i.e. free radicals, also catalyzed the oxidation reaction.
  • TEMPO In the presence of hydrogen peroxide, TEMPO first transfers to the nitro cation and then forms hydroxylamine. TEMPO goes through its reaction cycle and continues to induce H2O2 decomposition.
  • the optimum reaction temperature was 65°C.
  • the liquid ratio the ratio of fabric weight/solvent (eg, water) weight
  • the liquid ratio is optimized for the hydrogen peroxide process for maximum reactivity and minimum cost.
  • Figure 5 for liquid ratios less than 1:100, it is clear that the solvent is insufficient because the separation efficiency is reduced by 50%. While the samples were incubated at 1:100 and 1:200 in solution, the separation efficiency remained 100%. Therefore, a liquid ratio of 1:100 was chosen, which maintains high separation efficiency with minimal solvent (separating agent) consumption.
  • the isolated 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 Figure 6B.
  • the biological enzyme laccase is applied to the chemical enzymatic modification of cellulose.
  • TEMPO as a mediator, cellulose fibers were oxidized to small cellulose powders under mild aqueous conditions.
  • laccase induces oxidation of TEMPO, which then reacts with cellulose.
  • TEMPO+ is continuously regenerated by reacting with laccase, so C6 on cellulose continues to oxidize until all cellulose is oxidized, forming cellulose powder.
  • the PET fibers remained unchanged in the oxidase reaction.
  • the concentration of laccase was first optimized by varying the concentration from 0.5 mg/mL to 45 mg/mL. As shown in Figure 7, the separation efficiency increased significantly with increasing laccase concentration until its concentration reached 30 mg/mL. It shows that the concentration of laccase is one of the key factors for the separation of this oxidase method. 30 mg/mL of laccase was the optimal concentration for this reaction.
  • the weight ratio of laccase to TEMPO also had an effect on the separation efficiency. As shown in Figure 8, small changes in ratios have a large impact on separation performance in oxidase-based separations.
  • the preferred weight ratio of laccase to TEMPO is 2:1, which helps to further improve the separation efficiency of the 30 mg/mL laccase solution and promotes the complete separation of the cotton/PET mixture.
  • the oxidase showed consistent separation efficiency over a working temperature range of 40°C to 55°C.
  • the temperature between 40°C and 50°C was considered to be the optimal reaction temperature of the separation system, which matched the properties of laccase, and the enzyme activity was the highest in this temperature range.
  • the laccase activity is low and additional reaction time is required to complete the separation.
  • the pH value affects the properties of the enzyme (laccase).
  • laccase laccase
  • the present disclosure investigates the effect of pH on the oxidase system. As shown in Figure 11, the separation is between pH 4 and 6, such as 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 the loss of enzyme activity at high pH.
  • the liquid ratio of the oxidase separation was investigated to minimize the consumption of reagents. As shown in Figure 12, the separation efficiency was optimized under different liquid ratios, where the liquid ratio was between 1:50 and 1:200, and the optimal liquid ratio was 1:100, which could achieve complete separation with minimal reagent consumption.
  • the PET and cellulose powders separated by the oxidase reaction were subjected to SEM imaging and FTIR analysis, and the results are shown in Figure 13A and Figure 13B, respectively.
  • the results were similar to the hydrogen peroxide method, showing a high degree of agreement between the two reactions.
  • the present disclosure selects a PET-cotton (52:48 weight ratio) blend as an example to demonstrate the success of the hydrogen peroxide separation method.
  • the method provided by the present disclosure is a fast, energy-efficient, and non-toxic separation method for cotton-PET mixtures.
  • the isolated PET still has good properties and can be reused directly in the textile industry, while the cellulose powder becomes short fiber form, which can be spun into long fibers and filaments for future use.

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Abstract

一种分离混纺织品中涤纶和棉的方法，在TEMPO存在下，使混纺织物与过氧化氢或氧化酶相接触，发生化学(过氧化氢)或生物(氧化酶)反应使棉被氧化而保留了PET。该方法为棉/PET混纺织物提供了一种绿色、无毒且节能的处理方法。

Description

分离混纺织品中涤纶和棉的方法 技术领域
本公开涉及一种从混合纺织品中分离涤纶(聚对苯二甲酸乙二酯(PET))和棉的方法。更具体地，本公开涉及通过氧化反应将混纺织物的PET和棉相分离的方法。
背景技术
纺织品废物处理是一个突显问题，在垃圾掩埋和焚烧中导致环境问题，造成负面影响。另外，由于纤维的物理和化学性质不同，混纺织物废物在回收时面临挑战性。
为了解决这个问题，通过选择性地溶解或降解PET和棉中的一种而开发了几种PET和棉的分离方法，以实现分离并再利用所选择的PET或棉。这些方法包括通过(i)用酸或微生物降解棉花，或(ii)用离子液体或N-甲基吗啉N-氧化物溶解棉，该方法昂贵。还提出了使用聚酯的水解和醇解使棉保留下来而使聚酯解聚的方法。在PET-棉的混合织物的现有分离方法中，均无法同时保留纤维素和PET。
用于PET-棉混合物的绿色分离方法很有限。现有的再循环或再利用方法可能需要有机/离子溶剂、高温或高成本。而且，上述方法通过改变其固有特性而对回收材料的影响很小。
发明内容
因此，本公开的目的是提供一种通过化学氧化(基于H 2O 2的氧化)和氧化酶的氧化(漆酶，laccase)来分离PET-棉混纺织物中棉与PET的方法。
在第一方面，本文提供了基于H 2O 2的氧化方法，该方法用于在作为氧化剂的H 2O 2和作为催化剂的2,2,6,6-四甲基哌啶-氮-氧化物(TEMPO)的存在下使棉经受氧化，使棉纤维变为棉粉，而在此过程中PET保持纤维形式。
本公开提供的使PET-棉混纺织物中PET与棉相分离的方法包括以下步骤：在TEMPO存在下，使混纺织物与过氧化氢或氧化酶相接触；其中与过氧化氢接触的方法称为过氧化氢法，与氧化酶(例如漆酶)接触的方法称为氧化酶法。
根据一些实施方式，在过氧化氢法中，将PET-棉混纺织物与浓度为1％至10％(v/H2O v)的过氧化氢(H 2O 2)，在浓度为0.1％至5.0％(w/v)的TEMPO的存在下，于55℃至65℃的温度，pH 8至10，搅拌，反应体系的液比为1：50至1：300，反应时间为6-48小时。
根据一些实施方式，过氧化氢的浓度为8％至10％。根据一些实施方式，过氧化氢的浓度为10％。
根据一些实施方式，TEMPO的浓度为0.5％至2.0％(w/v)。根据一些实施方式，TEMPO的浓度为0.8％至1.5％(w/v)。根据一些实施方式，TEMPO的浓度为0.1％至1.0％(w/v)。根据一些实施方式，TEMPO的浓度为1.0％(w/v)
根据一些实施方式，反应体系的pH值为8至10。根据一些实施方式，反应体系的pH值为9至10。根据一些实施方式，反应体系的pH值为10。
根据一些实施方式，反应时间为6-30小时。根据一些实施方式，反应时间为6-24小时。根据一些实施方式，反应时间为24小时。
根据一些实施方式，反应温度为60至65℃。根据一些实施方式，反应温度为65℃。
根据一些实施方式，反应体系的液比为1：75至1：250。根据一些实施方式，反应体系的液比为1：100至1：200。根据一些实施方式，反应体系的液比为1：100至1：150。根据一些实施方式，反应体系的液比为1：100。
根据一些实施方式，在氧化酶法中，将PET-棉混纺织物与氧化酶(例如漆酶)孵育，所述酶的浓度为0.5至55mg/mL，TEMPO的浓度为3.75mg/mL至60mg/mL，所述酶的工作温度为20℃至60℃，pH范围为3至6，反应体系的液比为1：50至1：300，反应时间为2-72小时。
根据一些实施方式，氧化酶与TEMPO的重量比为0.5-8：1。根据一些实施方式，氧化酶与TEMPO的重量比为1-4：1。根据一些实施方式，氧化酶与TEMPO的重量比为1-3：1。根据一些实施方式，氧化酶与TEMPO的重量比为2：1。
根据一些实施方式，氧化酶为漆酶。
根据一些实施方式，氧化酶的浓度为25至50mg/mL。根据一些实施方式，氧化酶的浓度为30至45mg/mL。根据一些实施方式，氧化酶的浓 度为30至40mg/mL。根据一些实施方式，氧化酶的浓度为30mg/mL。
根据一些实施方式，TEMPO的浓度为7.5至30mg/mL。根据一些实施方式，TEMPO的浓度为10至22.5mg/mL。根据一些实施方式，TEMPO的浓度为15mg/mL。
根据一些实施方式，氧化酶的工作温度为40℃至60℃。根据一些实施方式，氧化酶的工作温度为40℃至55℃。根据一些实施方式，氧化酶的工作温度为40℃至50℃。
根据一些实施方式，氧化酶的工作pH值为3至4。根据一些实施方式，氧化酶的工作pH值为4至5。根据一些实施方式，氧化酶的工作pH值为4至4.5。根据一些实施方式，氧化酶的工作pH值为4。
根据一些实施方式，氧化酶法中，反应体系的液比为1：50-1：250。根据一些实施方式，氧化酶法中，反应体系的液比为1：100-1：200。根据一些实施方式，氧化酶法中，反应体系的液比为1：100-1：150。根据一些实施方式，氧化酶法中，反应体系的液比为1：100。
根据一些实施方式，氧化酶法的反应时间为5至50小时。根据一些实施方式，氧化酶法的反应时间为8至48小时。根据一些实施方式，氧化酶法的反应时间为8至36小时。根据一些实施方式，氧化酶法的反应时间为36小时。根据一些实施方式，氧化酶法的反应时间为8小时。
在一些实施方式中，通过从1％至10％(v/H2O v)的梯度来研究H 2O 2浓度的影响。在反应中，H 2O 2分解并生成一个羟基自由基，进攻纤维素上的碳原子，从而导致羟基形成羧基。因此，将纤维素纤维切成纤维素粉末以达到分离目的。
在一些实施方式中，H 2O 2的氧化能力由TEMPO催化，通过将其浓度从0.1％到5.0％(w/H2O v)的变化研究了TEMPO的催化作用。
在一些实施方式中，通过将反应温度从55℃变为65℃来研究温度对分离效率的影响。
在一些实施方式中，由于pH与H 2O 2的分解速率高度相关，因此通过将反应从pH 8改变为pH 10阐释了pH效应。
在一些实施方式中，研究了分离效率与反应时间的关系。
在一些实施方式中，液比从1：50变化至1：200以验证反应行为和分离性能。
在一些实施方式中，通过简单过滤将棉粉和PET纤维分离，然后洗涤和干燥。分离效率定义为收集的分离产品(棉或PET)与原始纺织品中的棉或PET的重量百分比。
在一些实施方式中，分离的棉和PET被进一步鉴定并通过FTIR和SEM表征，以显示产品的质量和纯度。
本文提供的氧化酶法可以利用漆酶/TEMPO体系。简而言之，选择来自曲霉属的漆酶来实施该方法。在催化剂TEMPO的存在下，漆酶充当氧化剂以选择性地将纤维素纤维氧化为纤维素粉末。空气中氧气的存在会引起漆酶的氧化，随后是TEMPO和纤维素上的羟基的氧化，从而形成纤维素粉末，而PET仍以纤维形式存在。
在一些实施方式中，漆酶的浓度从0.5至45mg/mL变化。
在一些实施方式中，通过漆酶与TEMPO的重量比为0.5至8：1(wt/wt)来证明TEMPO催化能力的效果。
在一些实施方式中，通过氧化酶的氧化反应通过从室温至55℃的变化来研究反应温度的影响。
在一些实施方式中，监测反应时间4小时至3天来表明分离程度。
在一些实施方式中，将反应的pH值在4至6间变化来考察pH的影响。
在一些实施方式中，液比从1:50变化至1：200以考察反应行为和分离性能。
在一些实施方式中，通过简单过滤将棉粉和PET纤维分离，然后洗涤和干燥。分离效率定义为收集的分离产品(棉或PET)和原始纺织品中的棉或PET的重量百分比。
在一些实施方式中，分离的棉花和PET被进一步鉴定并通过FTIR和SEM表征，以显示产品的质量和纯度。
以PET/棉＝52：48(wt/wt)的纺织品作为测试样品。
附图说明
以下通过结合附图对本公开进行详细说明。
图1显示了在过氧化氢法中，在0.1％TEMPO(w/H2O v)、pH 10、55℃、液比1：100、24小时反应的条件下，H 2O 2浓度与分离效率之间的关系。
图2显示了在过氧化氢法中，在55℃、10％H 2O 2(v/H2O v)、1：100的液比、0.1％TEMPO(w/H2O v)的条件下，pH和反应时间对分离的影响。
图3显示了在过氧化氢法中，在pH 8、10％H 2O 2(v/H2O v)、1％TEMPO(w/H2O v)、液比为1：100、24h反应的条件下，温度对分离的影响。
图4显示了在过氧化氢法中，在pH 8、55℃、10％H 2O 2(v/H2O v)、液比1：100、24小时反应的条件下，TEMPO浓度与分离效率之间的关系。
图5显示了在pH 8、65℃下24小时使用10％H 2O 2和1％TEMPO对液比的影响对分离效率的影响。
图6A显示了在过氧化氢法中分离的纤维(PET)和粉末(纤维素)的照片和SEM图像。
图6B示例性示出了过氧化氢法中分离的纤维和粉末的傅里叶变换红外(FTIR)光谱，以及与它们的原料的光谱比较。
图7显示了在氧化反应中，在40℃下在pH 4下、漆酶：TEMPO＝1：1(wt/wt)，液比为1：200，进行72小时的氧化反应中漆酶浓度对分离的影响。
图8显示了漆酶氧化体系中TEMPO的催化效果，其中漆酶的浓度保持在30mg/mL，在40℃、pH 4下，反应8小时维持漆酶为最佳浓度。
图9显示了在漆酶与TEMPO之比为2：1(wt/wt)、40℃、pH 4下持续72h，温度对漆酶氧化体系的影响。
图10显示了漆酶氧化体系的反应时间与分离效率的关系，在最佳条件下监测分离效率2至48小时。
图11显示了氧化酶法分离中的pH值影响(pH 4至6)。
图12显示了氧化酶法中液比与分离效率之间的关系。
图13A显示了氧化酶法分离的纤维(PET)和粉末(纤维素)的照片和SEM图像。
图13B示例性示出氧化酶法分离的纤维和粉末的傅里叶变换红外(FTIR)光谱，并与其原料进行了光谱比较。
详细说明
本公开内容的范围不受本文描述的任何具体实施方式的限制。以下实施方式仅作为示例来说明。
本公开的分离方法被开发用于PET-棉共混物的分离。它涉及两个提到的机制，包括过氧化氢法体系和氧化酶法体系，以略微改变纤维素纤维成为纤维素粉末，通过简单的过滤实现绿色分离并回收这些材料。
在本公开中，上述两种分离方法具有很大的潜力，它们通过这些无预处理和无选择方法分离不同比例的PET-棉共混物。
提及的过氧化氢法和氧化酶法都涉及在催化剂TEMPO存在下对纤维素的氧化以生成短纤维素纤维。因此，PET长纤维通过简单的过滤就能与短棉纤维分离。
这些分离方法对棉与PET的比例不限制，通过上述方法将这两种材料的任何比例的织物都转为纤维素粉末和PET纤维。
在过氧化氢法中，将棉-PET共混物简单地置于H 2O 2-TEMPO溶液中，然后在温和的加热和搅拌下开始棉的氧化反应。H 2O 2-TEMPO溶液的颜色从橙色变为无色，表明反应完成。
H 2O 2在控制分离效率中起着重要作用。如图1所示，随着H 2O 2浓度的增加(特别是从8％至10％)，分离效率增加。由于高浓度的H 2O 2的快速分解，在施加10％的H 2O 2时可实现完全分离。
在过氧化氢法的分离中，pH还影响H 2O 2的分解。如图2所示，通过比较不同pH条件下分离体系的总体性能，pH 10的分解始终优于pH 9和pH 8。H 2O 2的分解取决于pH，较高的pH分解速度更快。因此，较高的pH有利于反应。
如图2所示，过氧化氢法分离的最佳反应时间为24h，织物可实现完全分离。
温度对过氧化氢法的分离效率的影响是分离效率随温度而增加。如图3所示，温度从55℃升高到65℃，TEMPO从0.1％增加到1％，使得分离在pH8(更中性的环境)下发生，此时提供了更多的能量来启动氧化反应。此外，TEMPO即自由基的增加也催化了氧化反应。在过氧化氢的存在下，TEMPO首先会转移到硝基阳离子上，然后形成羟胺。TEMPO经历其反应周期，并继续诱导H2O2分解。最佳反应温度为65℃。
TEMPO在过氧化氢法中的作用是清楚的。如图4所示，TEMPO的存 在将分离效率从0.1％提高到1％，但是，TEMPO的过量会抑制过氧化氢法的分离。
液比，即织物重量/溶剂(例如水)重量的比率，针对过氧化氢法进行了优化，以具有最大的反应能力和最低的成本。如图5所示，对于小于1：100的液比，由于分离效率降低了50％，显然溶剂不足。而样品在溶液中以1：100和1：200的溶液温育时，分离效率保持100％。因此，选择液比为1：100，它保持了高分离效率且溶剂(分离剂)消耗最少。
显微图像通过SEM捕获，在pH值为8的情况下，对PET纤维的损伤很小，显示出保持原始PET纤维的出色性能。通过SEM表征分离的纤维素粉末和PET纤维。氧化反应后，表面PET纤维保持光滑，而棉花变成短纤维素碎片。如图6A所示。
通过FTIR鉴定分离的纤维素粉末和PET。分离出的纤维被鉴定为纯PET，且分离出的粉末被鉴定为纯棉，如图6B所示。
在氧化酶法中，将生物酶漆酶应用于纤维素的化学酶修饰。在TEMPO作为介导物质的存在下，纤维素纤维在温和的水性条件下被氧化成小的纤维素粉末。在此有氧反应中，漆酶诱导TEMPO氧化，然后氧化的TEMPO与纤维素反应。同时，TEMPO+通过与漆酶反应不断再生，因此，纤维素上的C6继续氧化，直到所有纤维素被氧化，形成纤维素粉末。而PET纤维在氧化酶的反应中保持不变。
首先将浓度从0.5mg/mL到45mg/mL的变化来优化漆酶的浓度。如图7所示，分离效率随着漆酶浓度的增加而明显增加，直至其浓度达到30mg/mL。表明漆酶浓度是该氧化酶法分离的关键因素之一。30mg/mL的漆酶是该反应的最佳浓度。
漆酶与TEMPO的重量比对分离效率也有影响。如图8所示，比率的小变化在氧化酶法分离中对分离性能产生很大影响。漆酶与TEMPO的优选重量比为2：1，助于进一步提高30mg/mL漆酶溶液的分离效率，促进棉/PET混合物的完全分离。
如图9所示，氧化酶的工作温度范围为40℃至55℃下显示出分离效率的一致性。40℃至50℃的温度被认为是该分离体系的最佳反应温度，与漆酶的性质相匹配，在该温度范围内酶活性最高。
对于氧化酶法的反应，将温度从40℃降低至室温，漆酶的活性低，并 且需要额外的反应时间以完成分离。
监测氧化酶法的分离，如图10所示，8h时发现完全分离，表明该方法可实现快速分离。
pH值会影响酶(漆酶)的性质。本公开研究了pH对氧化酶的体系的影响。如图11所示，在pH 4至6之间，例如pH 4至5之间分离。最适pH被认为是pH 4，pH的增加影响分离程度。这可能是由于高pH下酶的活性丧失所致。
类似于先前的过氧化氢法反应，研究了氧化酶法分离的液比以最小化试剂的消耗。如图12所示，在不同的液比下优化分离效率，其中液比在1:50至1：200之间，最佳液比为1：100，可以最少的试剂消耗实现完全分离。
将氧化酶反应分离出的PET和纤维素粉末进行SEM成像和FTIR分析，结果分别见图13A和图13B。结果类似于过氧化氢法，显示出两个反应的高度一致性。
本公开选择PET-棉(52：48重量比)共混物作为实例证明了过氧化氢法分离方法的成功。
具体实施方式
以下将举例说明本公开的分离方法，而无意于对这些分离方法做任何限定。
实施例1
过氧化氢法
将1kg的TEMPO和100L的10％H 2O 2与1kg待处理纺织品(棉与PET混合比为52：48)混合，在pH 8、65℃、液比1：100的条件下搅拌24个小时，然后过滤，将棉粉和PET纤维分离，经洗涤和干燥后分别得到0.52kg的PET和0.48kg的棉粉。分离的PET纤维和棉粉(纤维素)的照片和SEM图像参见图6A，傅里叶变换红外(FTIR)光谱及其与原料的光谱比较参见图6B。
实施例2
氧化酶法
将15mg/mL TEMPO和30mg/mL漆酶与1kg待处理纺织品(棉与PET的混合比为52：48)混合，在40℃、pH 4、液比1：100的条件下搅拌8h，然后过滤，将棉粉和PET纤维分离，经洗涤和干燥后分别得到0.52kg的PET和0.48kg的棉粉。分离的PET纤维和棉粉(纤维素)的照片和SEM图像参见图13A，傅里叶变换红外(FTIR)光谱及其与原料的光谱比较参见图13B。
工业实用性
本公开提供的方法是用于棉-PET混合物的快速、节能且无毒的分离方法。分离出的PET仍然具有很好的性能，可以直接在纺织工业中重复使用，而纤维素粉末变成短纤维形式，可以纺制成长纤维和长丝以备将来使用。

Claims (10)

  1. PET-棉混纺织物中PET与棉相分离的方法，其特征在于，所述方法包括以下步骤：在TEMPO存在下，使混纺织物与过氧化氢或氧化酶相接触，发生氧化反应；其中与过氧化氢接触的方法称为过氧化氢法，与氧化酶接触的方法称为氧化酶法。
  2. 根据权利要求1所述的方法，其特征在于，所述氧化酶是漆酶。
  3. 根据权利要求1所述的方法，其特征在于，在过氧化氢法中，将PET-棉混纺织物与体积比浓度为1％至10％的过氧化氢，在重量体积比浓度为0.1％至5.0％的TEMPO的存在下，于55℃至65℃的温度，pH 8至10，搅拌，反应体系的液比为1：50至1：300，反应时间为6至48小时。
  4. 根据权利要求1或3所述的方法，其特征在于，过氧化氢的浓度为8％至10％；或TEMPO浓度为0.5％至2.0％；或pH为9至10；或反应时间为6-24小时；或反应温度为60-65℃；或液比为1：100至1：200。
  5. 根据权利要求4所述的方法，其特征在于，过氧化氢的浓度为10％；或TEMPO浓度为1.0％；或pH为10；或反应时间为24小时；或反应温度为65℃；或液比为1：100。
  6. 根据权利要求1或2所述的方法，其特征在于，在氧化酶法中，将PET-棉混纺织物与氧化酶孵育，所述酶的浓度为0.5至55mg/mL，TEMPO的重量体积比浓度为3.75mg/mL至60mg/mL，所述酶的工作温度为20℃至60℃，pH范围为3至6，反应体系的液比为1：50至1：300，反应时间为2-72小时。
  7. 根据权利要求6所述的方法，其特征在于，所述酶的浓度为25-50mg/mL；或所述酶的工作温度为40℃至55℃；或反应体系的pH范围为4至5；或反应体系的液比为1：100-1：200；或反应时间为8至48小时。
  8. 根据权利要求6或7所述的方法，其特征在于，所述酶的浓度为30mg/mL；或所述酶的工作温度为40℃至50℃；或反应体系的pH范围为4；或反应体系的液比为1：100；或反应时间为8小时。
  9. 根据权利要求1、2、6至8中任一项所述的方法，其特征在于，所述酶与TEMPO的重量比为0.5-8：1。
  10. 根据权利要求9所述的方法，其特征在于，所述酶与TEMPO的重量比为2：1。
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