Method for efficiently decolorizing, deironing and activating waste fabric

Abstract

The invention provides a method for efficiently decolorizing, deironing and activating waste fabrics, and belongs to the technical field of waste fabric recycling, the method comprises the following steps: putting preliminarily cleaned waste fabrics in a decolorizing solution containing an alkaline substance and a decolorizing agent, carrying out gradient heating to 30-55 DEG C as a final temperature, and carrying out decolorizing treatment at the final temperature, and placing the decolored fiber in a pickling solution containing polyethylene glycol, and carrying out pickling to obtain the treated textile. The invention provides a high-efficiency and environment-friendly decolorizing and activating treatment method for textiles, which can remarkably improve the removal efficiency of dyes and perfectly considers the whiteness quality and mechanical properties of the textiles at the same time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste fabric recycling, and particularly relates to a method for efficient decolorization and iron removal and activation of waste fabric. BACKGROUND

[0002] In the chemical recycling process of waste textiles, complex dyes (including but not limited to reactive dyes), auxiliaries, oil stains and difficult-to-remove foreign matters remaining on the fabric constitute the core difficulty of decolorization treatment. These substances not only directly affect the reaction efficiency of the decolorizing agent and the whiteness of the target fiber, but also cause equipment blockage and quality defects of regenerated fibers in the subsequent spinning or fiber forming process.

[0003] Meanwhile, in the existing iron removal process, excessive contact of the pickling solution with the fiber can cause decomposition of cellulose in the fiber, affecting the degree of polymerization thereof. SUMMARY

[0004] In view of the above problems, the present application relates to a method for efficient decolorization and iron removal and activation of waste cotton textiles. The method realizes efficient recycling of waste fabric through adjustment of dosage, accurate temperature control, recycling and other technologies, thereby improving resource utilization efficiency and reducing environmental pollution.

[0005] To achieve the above-mentioned purposes, the technical solution adopted by the present application is as follows: A method for efficient decolorization and iron removal and activation of waste fabric, the method is to place the waste textiles after preliminary cleaning in a decolorizing solution containing an alkaline substance and a decolorizing agent, and to perform gradient heating to 30-55 DEG C as the final temperature, and to perform decolorization treatment under the condition of the final temperature, and to place the obtained decolorized fiber in a pickling solution containing polyethylene glycol, and to perform pickling, thereby obtaining the treated textiles.

[0006] Further, the gradient heating is to heat from the initial temperature to 30 DEG C at a heating rate of less than 2 DEG C / min, and to heat from 30 DEG C to the final temperature at a heating rate of less than 1.5 DEG C / min.

[0007] Further, the molecular weight of the polyethylene glycol is 200-2000.

[0008] Further, the content of the polyethylene glycol in the pickling solution is 1-3 g / L.

[0009] Further, the type of acid contained in the pickling solution is at least one of sulfuric acid, hydrochloric acid and citric acid. The content of the acid in the pickling solution is 8-15 g.

[0010] Further, the temperature of the pickling is 45-55 DEG C, and the time is 35-60 DEG C min.

[0011] Furthermore, the alkaline substance in the decolorizing solution is at least one of organic amine bases (such as ethanolamine, diethanolamine, triethanolamine, etc.), sodium silicate, magnesium hydroxide, sodium hydroxide, and sodium carbonate. The decolorizing agent in the decolorizing solution is at least one of peracetic acid, persulfate, and percarbonate.

[0012] Furthermore, the content of alkaline substances in the decolorizing solution is 20~30g / L, and the content of decolorizing agent is 10~25g / L.

[0013] Furthermore, the decolorization process takes 40-70 minutes.

[0014] Furthermore, the method includes the following specific steps: S1, Decolorization treatment Add alkaline substances and decolorizing agents to water, mix well, and prepare a decolorizing solution with an alkaline substance content of 20~30g / L and a decolorizing agent content of 10~25g / L; Take waste textiles and perform preliminary cleaning to remove surface contaminants and grease; At room temperature, the washed waste textiles are placed in a decolorizing solution with a liquor ratio of 1:20~40. The temperature is then increased from room temperature to 30℃ at a rate of less than 2℃ / min, and then increased from 30℃ to 30~55℃ at a rate of less than 1.5℃ / min. The decolorization reaction is carried out at 30~55℃ for 40~70 minutes. After the decolorization is completed, the solid and liquid are separated to obtain decolorized fibers. S2, Iron removal treatment Preparation of pickling solution: Add polyethylene glycol to the acid solution and mix well to form a pickling solution with a polyethylene glycol content of 1~3 g / L and an acid content of 8~15 g / L; Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 45~55℃ for 35~60℃ min; Pickling solution recovery: After pickling is complete, solid and liquid are separated to obtain the treated textiles; The liquid obtained from solid-liquid separation is returned to the pickling process and recycled as pickling solution 3-5 times, with 10-20% fresh pickling solution added each time.

[0015] The beneficial effects of the method for efficient decolorization, iron removal, and activation of waste fabrics according to the present invention are as follows: This invention provides a highly efficient and environmentally friendly method for decolorizing and activating textiles, which can significantly improve the efficiency of dye removal while perfectly maintaining the whiteness quality and mechanical properties of textiles. This invention can achieve a decolorization rate of over 98% for various reactive dyes (including azo, anthraquinone, phthalocyanine, etc.), especially for the removal of high-fastness reactive dyes with a molecular weight greater than 800. This invention has excellent whiteness retention effect, with the whiteness index of the treated textiles being ≥80, and can be applied to subsequent viscose spinning operations; This invention achieves the dual goals of efficient dye dissociation and fiber structure protection at the molecular level by precisely controlling the pH value, temperature gradient, and auxiliary agent ratio of the reaction system. Experimental data shows that compared with the traditional alkaline oxygen bleaching process, this invention can reduce fiber damage by more than 60% and shorten the decolorization time by 30%, truly achieving quality improvement and efficiency enhancement. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0017] Example 1: A method for efficient decolorization, iron removal, and activation of waste textiles This embodiment describes a method for efficient decolorization, iron removal, and activation of waste fabrics, specifically including the following steps: S1, Decolorization treatment S11. Add sodium hydroxide and peracetic acid to water, mix well, and prepare a decolorizing solution with sodium hydroxide content of 25 g / L and peracetic acid content of 18 g / L.

[0018] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease, so as to improve the decolorization and activation effect.

[0019] S13. At room temperature, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution are added to a rotary reactor at a liquor ratio of 1:30 (the liquor ratio is the mass ratio of waste textiles to decolorizing solution). The temperature is then increased from room temperature (20°C in this example) to 30°C at a heating rate of 2°C / min, and then increased from 30°C to 40°C at a heating rate of 1°C / min. The decolorization reaction is carried out at 40°C for 40 minutes to oxidize or hydrolyze the pigment molecular structure. During the decolorization process, the heating rate and temperature are controlled by gradient to avoid fiber damage. The decolorizing solution reacts effectively with the waste textiles in the rotary reactor to achieve the decolorization effect. After the decolorization is completed, the solid and liquid are separated (the solid and liquid separation method in this example is pressure filtration) to obtain decolorized fibers with a whiteness of 75 and a degree of polymerization of 650.

[0020] The principle behind the decolorization is as follows: Reactive dyes are a class of dyes whose molecules contain reactive groups (such as chlorotriazine, vinyl sulfone, etc.), which can form covalent bonds with fibers (such as cotton, linen). Their decolorization requires the simultaneous destruction of both the chromophore (azo, anthraquinone, etc.) and the reactive group. Under the action of the alkaline oxidative composite system (i.e., the decolorizing solution) of this invention, the decolorization mechanism includes: Alkaline hydrolysis: breaks the dye-fiber bond, releasing soluble dye molecules.

[0021] Oxidative degradation: destroys chromophores (such as azo bonds and anthraquinone rings) and active groups.

[0022] Mineralization: Ultimately produces CO2, H2O and inorganic salts.

[0023] The alkaline components (NaOH, Na2CO3, sodium silicate, etc.) in the alkaline oxidation composite system of this invention function as follows: hydrolyzing active groups; breaking dye-fiber bonds to release free dye molecules (which are more easily oxidized), such as Dye-Cl+OH. - →Dye-OH+Cl - (Taking the hydrolysis of chlorotriazine groups as an example); increasing dye solubility and anionizing the dye (e.g., sulfonic acid group -SO3). - Increased solubility); stabilizes oxidants, such as alkaline environments can inhibit the ineffective decomposition of oxidants such as H2O2 and NaClO (e.g., H2O2 is more likely to generate ·OH free radicals under alkaline conditions).

[0024] For anthraquinone dyes, the decolorization mechanism is as follows: Typical anthraquinone dyes (such as Reactive Brilliant Blue KN-R and Disperse Blue 56) have the following general structural formula: anthraquinone core = C 14 H8O2 (containing two carbonyl groups and three benzene rings) is key to decolorization by breaking the C=O bond or disrupting the conjugation of the aromatic ring. Under the action of the alkaline oxidative composite system (i.e., the decolorizing solution) of this invention, the dye is first dissolved. Anthraquinone dyes may form phenolates (-O-) under alkaline conditions, increasing their water solubility; taking hydroxyanthraquinone as an example: C 14 H7O2OH+OH - →C 14 H7O2O - +H2O. Secondly, it stabilizes the oxidizing agent; an alkaline environment can inhibit the ineffective decomposition of oxidizing agents such as H2O2 and NaClO (for example, H2O2 is more likely to generate ·OH free radicals under alkaline conditions). The reaction mechanism of the oxidative decolorizing agent for anthraquinone dyes is as follows: Different oxidants attack anthraquinone dyes at different sites, and common pathways include: Peracetic acid (CH3COOOH) cleaves the anthraquinone ring via free radical (·OH) oxidation, as shown in the following reaction formula: C 14H8O2 + 4CH3COOOH → 3C6H4(COOH)2 + 2CO2 + 4CH3COOH (the products are phthalic acid and acetic acid).

[0025] Percarbonate (2Na2CO3·3H2O2) oxidizes anthraquinone to carboxylic acid by releasing H2O2, as shown in the following reaction formula: C 14 H8O2 + 5H2O2 + 4OH- - →2C6H4(COO - )2+2HCOO - +6H2O (products are oxalate and formate) The reaction formula for the oxidative decolorization of anthraquinone dyes by persulfates (such as K2S2O8) is as follows: C 14 H8O2+4S2O8 2- +6OH - →2C6H5COO - +2CO3 2- +8SO4 2- +4H2O For azo dyes, the decolorization mechanism is as follows: Different oxidants attack azo dyes at different sites, and common pathways include: Peracetic acid (CH3COOOH) cleaves the chromophore and reactive group through free radical (·OH) oxidation. Assuming the molecular structure of an azo dye is: Dye1-Ar-N=N-Ar'-SO2CH=CH2 (where Ar and Ar' represent aromatic rings), the reaction formula is: Dye1-Ar-N=N-Ar'-SO2CH=CH2+2CH3COOOH→Dye1-Ar-NH2+O=Ar'-COOH+CH3COOH+SO4 2- (During the reaction, the sulfone active group is oxidized to carboxylic acid and sulfate).

[0026] Percarbonate (2Na2CO3·3H2O2) oxidizes azo bonds and aromatic rings by releasing H2O2, as shown in the following reaction: Dye1-Ar-N=N-Ar'-SO2CH=CH2+2H2O2→Dye1-Ar-NH2+H2N-Ar'-SO2CH=CH2+N2 Persulfates (such as K2S2O8) generate sulfate radicals (SO4) through heat / alkali activation. - Strong oxidizing ring-opening degradation of aromatic rings, the reaction formula is: Dye1-Ar-N=N-Ar'-SO2CH=CH2+aSO4 - → Multiple {CO2+SO4}2- +H + +H2O+NO3 -}

[0027] S2, Iron removal treatment S21. Preparation of pickling solution: Add polyethylene glycol 400 (PEG400) to sulfuric acid aqueous solution and mix well to form a pickling solution with polyethylene glycol 400 content of 1g / L and sulfuric acid content of 8g / L.

[0028] S22. Pickling Treatment: Place the decolorized fibers in a pickling solution and pickle at 50°C for 55 minutes; a polyethylene glycol-protected pickling method is used, employing a pickling solution formed by adding polyethylene glycol to dilute acid. The acid in the pickling solution converts the Fe in the decolorized fibers into Fe2+. 3+ Furthermore, by encapsulating the cellulose in the decolorized fibers with polyethylene glycol, excessive contact of acid with cellulose is prevented, cellulose decomposition is reduced, and its degree of polymerization is protected, with a fiber degree of polymerization retention rate of ≥95%. At the same time, polyethylene glycol also encapsulates Fe 3+ Fe in polyethylene glycol and decolorized fibers 3+ A soluble complex is formed, which allows Fe to be released from the encapsulation of the decolorized fiber, reducing the Fe content in the decolorized fiber; the Fe content in the decolorized fiber before treatment is ≥150ppm, while the Fe content in the decolorized fiber after treatment is ≤20ppm; The principle of pickling in this invention is as follows: (1) Dissolving Fe2O3 / Fe adsorbed by decolorizing fibers 3+ Oxides: Fe2O3+6H + →2Fe 3+ +3H2O; Fe3O4+8H + →Fe 2+ +2Fe 3+ +4H2O; (2) A hydrogen-bonded protective layer is formed to encapsulate the molecular chains of decolorized cellulose, inhibiting acid hydrolysis of cellulose: Cellulose-OH+HO-(CH2CH2O) n -H→Cellulose-O-(CH2CH2O) n -H (hydrogen bond); (3) Iron complexation reaction to capture [PEG-FeSO4] + Complexes: PEG+Fe 3+ +3SO4 2- →[PEG·Fe(SO4)3] 3- (Water-soluble complex).

[0029] S23. Pickling solution recovery: After pickling is complete, solid and liquid are separated (in this embodiment, the solid and liquid separation method is pressure filtration) to obtain the treated textile with a whiteness of 80, a degree of polymerization of 570, and an iron content of 18.7 ppm.

[0030] The liquid obtained from solid-liquid separation is returned to step S22 and recycled as pickling solution 3 to 5 times, with 10 to 20% fresh pickling solution added each time.

[0031] Example 2: A method for efficient decolorization, iron removal, and activation of waste textiles This embodiment describes a method for efficient decolorization, iron removal, and activation of waste fabrics, specifically including the following steps: S1, Decolorization treatment S11. Add triethanolamine, sodium carbonate and ammonium persulfate to water, mix well, and prepare a decolorizing solution with a triethanolamine content of 15 g / L, a sodium carbonate content of 5 g / L and an ammonium persulfate content of 20 g / L.

[0032] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0033] Under S13 and 20℃ conditions, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:20. The temperature was then increased from 20℃ to 30℃ at a rate of 1.5℃ / min, and then from 30℃ to 50℃ at a rate of 1.2℃ / min. The decolorization reaction was carried out at 50℃ for 60 min. After the decolorization was completed, the product was filtered to obtain decolorized fibers with a whiteness of 78 and a degree of polymerization of 580.

[0034] S2, Iron removal treatment S21. Preparation of pickling solution: Add polyethylene glycol 2000 (PEG2000) to hydrochloric acid aqueous solution, mix well, and form a pickling solution with polyethylene glycol 2000 content of 2g / L and hydrochloric acid content of 14g / L.

[0035] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 45°C for 60 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textiles, which have a whiteness of 82, a degree of polymerization of 540, and an iron content of 17.2 ppm.

[0036] The liquid obtained from solid-liquid separation is returned to step S22 and recycled as pickling solution 3 to 5 times, with 10 to 20% fresh pickling solution added each time.

[0037] Example 3: A method for efficient decolorization, iron removal, and activation of waste textiles This embodiment describes a method for efficient decolorization, iron removal, and activation of waste fabrics, specifically including the following steps: S1, Decolorization treatment S11. Add sodium hydroxide and sodium percarbonate to water, mix well, and prepare a decolorizing solution with a sodium hydroxide content of 30 g / L and a sodium percarbonate content of 10 g / L.

[0038] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0039] Under conditions of S13 and 20℃, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:40. The temperature was then increased from 20℃ to 30℃ at a rate of 2℃ / min, and then from 30℃ to 45℃ at a rate of 1℃ / min. The decolorization reaction was carried out at 45℃ for 40 minutes. After the decolorization was completed, the product was filtered to obtain decolorized fibers with a whiteness of 73 and a degree of polymerization of 720.

[0040] S2, Iron removal treatment S21. Preparation of pickling solution: Add polyethylene glycol 600 (PEG600) to citric acid aqueous solution and mix well to form a pickling solution with polyethylene glycol 600 content of 1g / L and citric acid content of 10g / L.

[0041] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 55°C for 60 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textiles, which have a whiteness of 77, a degree of polymerization of 640, and an iron content of 22.5 ppm.

[0042] The liquid obtained from solid-liquid separation is returned to step S22 and recycled as pickling solution 3 to 5 times, with 10 to 20% fresh pickling solution added each time.

[0043] Example 4: A method for efficient decolorization, iron removal, and activation of waste textiles This embodiment describes a method for efficient decolorization, iron removal, and activation of waste fabrics, specifically including the following steps: S1, Decolorization treatment S11. Add ethanolamine, magnesium hydroxide, peracetic acid and potassium persulfate to water, mix well, and prepare a decolorizing solution with ethanolamine content of 20 g / L, magnesium hydroxide content of 5 g / L, peracetic acid content of 14 g / L and potassium persulfate content of 7 g / L.

[0044] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0045] Under conditions of S13 and 20℃, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:35. The temperature was then increased from 20℃ to 30℃ at a rate of 1.8℃ / min, and then from 30℃ to 55℃ at a rate of 1.5℃ / min. The decolorization reaction was carried out at 55℃ for 45 minutes. After the decolorization was completed, the product was filtered to obtain decolorized fibers with a whiteness of 74 and a degree of polymerization of 450.

[0046] S2, Iron removal treatment S21. Preparation of pickling solution: Add polyethylene glycol 2000 (PEG2000) to a mixed aqueous solution of sulfuric acid and hydrochloric acid, mix well, and form a pickling solution with polyethylene glycol 2000 content of 2.4 g / L, sulfuric acid content of 10 g / L, and hydrochloric acid content of 5 g / L.

[0047] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 50°C for 40 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textiles, which have a whiteness of 80, a degree of polymerization of 375, and an iron content of 24.6 ppm.

[0048] The liquid obtained from solid-liquid separation is returned to step S22 and recycled as pickling solution 3 to 5 times, with 10 to 20% fresh pickling solution added each time.

[0049] Example 5: A method for efficient decolorization, iron removal, and activation of waste textiles This embodiment describes a method for efficient decolorization, iron removal, and activation of waste fabrics, specifically including the following steps: S1, Decolorization treatment S11. Add diethanolamine, sodium hydroxide and sodium percarbonate to water, mix well, and prepare a decolorizing solution with a diethanolamine content of 12 g / L, a sodium hydroxide content of 8 g / L and a sodium percarbonate content of 14 g / L.

[0050] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0051] Under conditions of S13 and 20℃, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:25. The temperature was then increased from 20℃ to 30℃ at a rate of 1.5℃ / min, and then increased from 30℃ to 55℃ at a rate of 1℃ / min. The decolorization reaction was carried out at 55℃ for 70 min. After the decolorization was completed, the mixture was filtered to obtain decolorized fibers with a whiteness of 80 and a degree of polymerization of 550.

[0052] S2, Iron removal treatment S21. Preparation of pickling solution: Add polyethylene glycol 1200 (PEG1200) to sulfuric acid aqueous solution, mix well to form a pickling solution with polyethylene glycol 1200 content of 1.8 g / L and sulfuric acid content of 10 g / L.

[0053] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 46℃ for 35 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textiles, which have a whiteness of 84, a degree of polymerization of 485, and an iron content of 21.7 ppm.

[0054] The liquid obtained from solid-liquid separation is returned to step S22 and recycled as pickling solution 3 to 5 times, with 10 to 20% fresh pickling solution added each time.

[0055] Example 6: A method for efficient decolorization, iron removal, and activation of waste textiles This embodiment describes a method for efficient decolorization, iron removal, and activation of waste fabrics, specifically including the following steps: S1, Decolorization treatment S11. Add magnesium hydroxide, peracetic acid, and sodium persulfate to water and mix well to obtain a decolorizing solution with a magnesium hydroxide content of 25 g / L, a peracetic acid content of 7 g / L, and a sodium persulfate content of 14 g / L.

[0056] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0057] Under conditions of S13 and 20℃, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:30. The temperature was then increased from 20℃ to 30℃ at a rate of 2℃ / min, and then from 30℃ to 50℃ at a rate of 1.3℃ / min. The decolorization reaction was carried out at 50℃ for 45 minutes. After the decolorization was completed, the mixture was filtered to obtain decolorized fibers with a whiteness of 74 and a degree of polymerization of 575.

[0058] S2, Iron removal treatment S21. Preparation of pickling solution: Add polyethylene glycol 800 (PEG800) to a mixed aqueous solution of citric acid and sulfuric acid, mix well, and form a pickling solution with polyethylene glycol 800 content of 1.6 g / L, citric acid content of 2 g / L, and sulfuric acid content of 9 g / L.

[0059] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 53°C for 55 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textiles, which have a whiteness of 70, a degree of polymerization of 515, and an iron content of 18.2 ppm.

[0060] The liquid obtained from solid-liquid separation is returned to step S22 and recycled as pickling solution 3 to 5 times, with 10 to 20% fresh pickling solution added each time.

[0061] Example 7: A method for efficient decolorization, iron removal, and activation of waste textiles This embodiment describes a method for efficient decolorization, iron removal, and activation of waste fabrics, specifically including the following steps: S1, Decolorization treatment S11. Add triethanolamine and potassium persulfate to water, mix well, and prepare a decolorizing solution with a triethanolamine content of 30 g / L and a potassium persulfate content of 25 g / L.

[0062] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0063] Under conditions of S13 and 20℃, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:30. The temperature was then increased from 20℃ to 30℃ at a rate of 1.5℃ / min, and then from 30℃ to 40℃ at a rate of 1℃ / min. The decolorization reaction was carried out at 40℃ for 65 minutes. After the decolorization was completed, the product was filtered to obtain decolorized fibers with a whiteness of 74 and a degree of polymerization of 575.

[0064] S2, Iron removal treatment S21. Preparation of pickling solution: Add polyethylene glycol 200 (PEG200) to hydrochloric acid aqueous solution, mix well to form a pickling solution with polyethylene glycol 200 content of 1.2 g / L and hydrochloric acid content of 15 g / L.

[0065] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 50°C for 60 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textiles, which have a whiteness of 84, a degree of polymerization of 500, and an iron content of 16.5 ppm.

[0066] The liquid obtained from solid-liquid separation is returned to step S22 and recycled as pickling solution 3 to 5 times, with 10 to 20% fresh pickling solution added each time.

[0067] Example 8: A method for efficient decolorization, iron removal, and activation of waste textiles. This embodiment describes a method for efficient decolorization, iron removal, and activation of waste fabrics, specifically including the following steps: S1, Decolorization treatment S11. Add sodium silicate, sodium hydroxide and sodium percarbonate to water, mix well, and prepare a decolorizing solution with sodium silicate content of 10 g / L, sodium hydroxide content of 15 g / L and sodium percarbonate content of 10 g / L.

[0068] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0069] Under conditions of S13 and 20℃, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:30. The temperature was then increased from 20℃ to 30℃ at a heating rate of 2℃ / min, and then from 30℃ to 55℃ at a heating rate of 1.4℃ / min. The decolorization reaction was carried out at 55℃ for 55 minutes. After the decolorization was completed, the product was filtered to obtain decolorized fibers with a whiteness of 70 and a degree of polymerization of 620.

[0070] S2, Iron removal treatment S21. Preparation of pickling solution: Add polyethylene glycol 1500 (PEG1500) to hydrochloric acid aqueous solution, mix well, and form a pickling solution with polyethylene glycol 1500 content of 1.4 g / L and hydrochloric acid content of 8 g / L.

[0071] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 47°C for 45 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textiles, which have a whiteness of 75, a degree of polymerization of 580, and an iron content of 19.8 ppm.

[0072] The liquid obtained from solid-liquid separation is returned to step S22 and recycled as pickling solution 3 to 5 times, with 10 to 20% fresh pickling solution added each time.

[0073] Example 9: A method for efficient decolorization, iron removal, and activation of waste textiles. This embodiment describes a method for efficient decolorization, iron removal, and activation of waste fabrics, specifically including the following steps: S1, Decolorization treatment S11. Add magnesium hydroxide, sodium carbonate and peracetic acid to water, mix well, and prepare a decolorizing solution with magnesium hydroxide content of 20 g / L, sodium carbonate content of 10 g / L and peracetic acid content of 25 g / L.

[0074] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0075] Under conditions of S13 and 20℃, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:30. The temperature was then increased from 20℃ to 30℃ at a rate of 1.8℃ / min, and then from 30℃ to 45℃ at a rate of 1.2℃ / min. The decolorization reaction was carried out at 45℃ for 50 min. After the decolorization was completed, the product was filtered to obtain decolorized fibers with a whiteness of 77 and a degree of polymerization of 590.

[0076] S2, Iron removal treatment S21. Preparation of pickling solution: Add polyethylene glycol 200 (PEG200) to sulfuric acid aqueous solution and mix well to form a pickling solution with polyethylene glycol 200 content of 2.4 g / L and sulfuric acid content of 15 g / L.

[0077] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 50°C for 60 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textiles, which have a whiteness of 84, a degree of polymerization of 540, and an iron content of 16.9 ppm.

[0078] The liquid obtained from solid-liquid separation is returned to step S22 and recycled as pickling solution 3 to 5 times, with 10 to 20% fresh pickling solution added each time.

[0079] Example 10: A method for efficient decolorization, iron removal, and activation of waste textiles. This embodiment describes a method for efficient decolorization, iron removal, and activation of waste fabrics, specifically including the following steps: S1, Decolorization treatment S11. Add triethanolamine, magnesium hydroxide, potassium persulfate and peracetic acid to water, mix well, and prepare a decolorizing solution with triethanolamine content of 25 g / L, magnesium hydroxide content of 5 g / L, potassium persulfate content of 10 g / L and peracetic acid content of 10 g / L.

[0080] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0081] Under conditions of S13 and 20℃, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:30. The temperature was then increased from 20℃ to 30℃ at a rate of 1.8℃ / min, and then from 30℃ to 45℃ at a rate of 1.2℃ / min. The decolorization reaction was carried out at 45℃ for 55 min. After the decolorization was completed, the product was filtered to obtain decolorized fibers with a whiteness of 78 and a degree of polymerization of 570.

[0082] S2, Iron removal treatment S21. Preparation of pickling solution: Add polyethylene glycol 600 (PEG600) to sulfuric acid aqueous solution and mix well to form a pickling solution with polyethylene glycol 600 content of 2 g / L and sulfuric acid content of 15 g / L.

[0083] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 50°C for 45 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textiles, which have a whiteness of 85, a degree of polymerization of 515, and an iron content of 15.7 ppm.

[0084] The liquid obtained from solid-liquid separation is returned to step S22 and recycled as pickling solution 3 to 5 times, with 10 to 20% fresh pickling solution added each time.

[0085] Example 11: A method for efficient decolorization, iron removal, and activation of waste textiles This embodiment describes a method for efficient decolorization, iron removal, and activation of waste fabrics, specifically including the following steps: S1, Decolorization treatment S11. Add sodium carbonate, sodium hydroxide and ammonium persulfate to water, mix well, and prepare a decolorizing solution with sodium carbonate content of 12 g / L, sodium hydroxide content of 8 g / L and ammonium persulfate content of 20 g / L.

[0086] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0087] Under S13 and 20℃ conditions, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:30. The temperature was then increased from 20℃ to 30℃ at a rate of 2℃ / min. The decolorization reaction was carried out at 30℃ for 70 min. After the decolorization was completed, the mixture was filtered to obtain decolorized fibers with a whiteness of 80 and a degree of polymerization of 580.

[0088] S2, Iron removal treatment S21. Preparation of pickling solution: Add polyethylene glycol 800 (PEG800) to sulfuric acid aqueous solution and mix well to form a pickling solution with polyethylene glycol 800 content of 3g / L and sulfuric acid content of 15g / L.

[0089] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 50°C for 55 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textiles, which have a whiteness of 85, a degree of polymerization of 520, and an iron content of 16.8 ppm.

[0090] The liquid obtained from solid-liquid separation is returned to step S22 and recycled as pickling solution 3 to 5 times, with 10 to 20% fresh pickling solution added each time.

[0091] Comparative Example 1: A method for efficient decolorization, iron removal, and activation of waste textiles This comparative example is a comparative experiment of a method for efficient decolorization, iron removal, and activation of waste fabrics in Example 1. In this comparative example, polyethylene glycol is not added during the iron removal process, and the other steps are almost identical to the method in Example 1, specifically including the following steps: S1, Decolorization treatment S11. Add sodium hydroxide and peracetic acid to water, mix well, and prepare a decolorizing solution with sodium hydroxide content of 25 g / L and peracetic acid content of 18 g / L.

[0092] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0093] Under S13 and 20℃ conditions, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:40. The temperature was then increased from 20℃ to 30℃ at a rate of 2℃ / min, and then from 30℃ to 40℃ at a rate of 1℃ / min. The decolorization reaction was carried out at 40℃ for 50 min. After the decolorization was completed, the product was filtered to obtain decolorized fibers with a whiteness of 75 and a degree of polymerization of 580.

[0094] S2, Iron removal treatment S21. Preparation of pickling solution: Take an aqueous solution of sulfuric acid with a sulfuric acid content of 10 g / L as the pickling solution.

[0095] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 50°C for 55 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textile with a whiteness of 80, a degree of polymerization of 320, and an iron content of 18.7 ppm.

[0096] It can be seen that, in this comparative example, because polyethylene glycol was not added during the iron removal process, the degree of polymerization of the fibers could not be protected, resulting in a significant decrease in the degree of polymerization of the final treated textiles.

[0097] Comparative Example 2: A method for efficient decolorization, iron removal, and activation of waste textiles This comparative example is a comparative experiment of a method for efficient decolorization, iron removal, and activation of waste fabrics in Example 1. In this comparative example, polyethylene glycol is not added during the iron removal process, and the other steps are almost identical to the method in Example 1, specifically including the following steps: S1, Decolorization treatment S11. Add sodium hydroxide and peracetic acid to water, mix well, and prepare a decolorizing solution with sodium hydroxide content of 25 g / L and peracetic acid content of 18 g / L.

[0098] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0099] Under conditions of S13 and 20℃, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:30. The temperature was then increased from 20℃ to 30℃ at a rate of 2℃ / min, and then from 30℃ to 40℃ at a rate of 1℃ / min. The decolorization reaction was carried out at 40℃ for 50 min. After the decolorization was completed, the product was filtered to obtain decolorized fibers with a whiteness of 75 and a degree of polymerization of 550.

[0100] S2, Iron removal treatment S21. Preparation of pickling solution: Take an aqueous solution of hydrochloric acid with a concentration of 10 g / L as the pickling solution.

[0101] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 50°C for 55 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textiles, which have a whiteness of 78, a degree of polymerization of 300, and an iron content of 19.2 ppm.

[0102] It can be seen that, in this comparative example, because polyethylene glycol was not added during the iron removal process, the degree of polymerization of the fibers could not be protected, resulting in a significant decrease in the degree of polymerization of the final treated textiles.

[0103] Comparative Example 3: A method for efficient decolorization, iron removal, and activation of waste textiles This comparative example is a comparative experiment of a method for efficient decolorization, iron removal, and activation of waste fabrics in Example 1. In this comparative example, the heating rate is not controlled during the decolorization process, and polyethylene glycol is not added during the iron removal process. The other steps are almost the same as the method in Example 1, specifically including the following steps: S1, Decolorization treatment S11. Add sodium hydroxide and peracetic acid to water, mix well, and prepare a decolorizing solution with sodium hydroxide content of 25 g / L and peracetic acid content of 18 g / L.

[0104] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0105] Under S13 and 20℃ conditions, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:30. The temperature was then raised to 50℃ (heating rate of about 2.5℃ / min), and the decolorization reaction was carried out at 50℃ for 55 min. After the decolorization was completed, the mixture was filtered to obtain decolorized fibers with a whiteness of 77 and a degree of polymerization of 480.

[0106] S2, Iron removal treatment S21. Preparation of pickling solution: Take an aqueous solution of hydrochloric acid with a concentration of 10 g / L as the pickling solution.

[0107] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 50°C for 55 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textiles, which have a whiteness of 79, a degree of polymerization of 240, and an iron content of 19.7 ppm.

[0108] It can be seen that in this comparative example, due to the failure to control the heating rate during the decolorization process, fiber damage could not be avoided, resulting in a significant decrease in the degree of polymerization of the final treated textile (mainly affecting the degree of polymerization, but the effect of temperature is relatively small; excessively high temperatures have a more significant impact on the degree of polymerization); and because polyethylene glycol was not added during the iron removal process, the degree of polymerization of the fibers could not be protected, resulting in a significant decrease in the degree of polymerization of the final treated textile.

[0109] Comparative Example 4: A method for efficient decolorization, iron removal, and activation of waste textiles This comparative example is a comparative experiment of a method for efficient decolorization, iron removal, and activation of waste fabrics in Example 1. In this comparative example, the heating rate was not controlled during the decolorization process, but the other steps were almost the same as those in Example 1, specifically including the following steps: S1, Decolorization treatment S11. Add sodium hydroxide and peracetic acid to water, mix well, and prepare a decolorizing solution with sodium hydroxide content of 25 g / L and peracetic acid content of 18 g / L.

[0110] S12. Take waste textiles containing reactive dyes (m-phenylenediamine dyes) and perform preliminary cleaning to remove surface contaminants and grease.

[0111] Under conditions of S13 and 20℃, the washed waste textiles containing reactive dyes (m-phenylenediamine dyes) and the decolorizing solution were added to a rotary reactor at a liquor ratio of 1:30. The temperature was then raised to 55℃ (heating rate of about 2.5℃ / min), and the decolorization reaction was carried out at 55℃ for 55 minutes. After the decolorization was completed, the mixture was filtered to obtain decolorized fibers with a whiteness of 76 and a degree of polymerization of 450.

[0112] S2, Iron removal treatment S21. Preparation of pickling solution: Add polyethylene glycol 400 (PEG400) to sulfuric acid aqueous solution and mix well to form a pickling solution with polyethylene glycol 400 content of 1g / L and sulfuric acid content of 10g / L.

[0113] S22. Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 50°C for 55 minutes. S23. Pickling solution recovery: After complete pickling, filter under pressure to obtain the treated textile with a whiteness of 81, a degree of polymerization of 380, and an iron content of 20.2 ppm.

[0114] It can be seen that, in this comparative example, the failure to control the heating rate during the decolorization process resulted in fiber damage, leading to a significant decrease in the degree of polymerization of the final treated textile.

[0115] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for efficient decolorization, iron removal, and activation of waste textiles, characterized in that, The method involves placing pre-cleaned waste textiles into a decolorizing solution containing alkaline substances and a decolorizing agent, gradually increasing the temperature to 30-55°C as the final temperature, and performing decolorization treatment at the final temperature. The resulting decolorized fibers are then placed in an acid washing solution containing polyethylene glycol for acid washing to obtain the treated textiles.

2. The method for efficient decolorization, iron removal, and activation of waste textiles according to claim 1, characterized in that, Gradient heating means that the heating rate is less than 2℃ / min when heating from the initial temperature to 30℃, and less than 1.5℃ / min when heating from 30℃ to the final temperature.

3. The method for efficient decolorization, iron removal, and activation of waste textiles according to claim 1 or 2, characterized in that, The molecular weight of polyethylene glycol is 200-2000.

4. The method for efficient decolorization, iron removal, and activation of waste textiles according to claim 1 or 2, characterized in that, The content of polyethylene glycol in the pickling solution is 1~3g / L.

5. The method for efficient decolorization, iron removal, and activation of waste textiles according to claim 1 or 2, characterized in that, The pickling solution contains at least one of sulfuric acid, hydrochloric acid, and citric acid. The acid content in the pickling solution is 8-15g.

6. The method for efficient decolorization, iron removal, and activation of waste textiles according to claim 1 or 2, characterized in that, The pickling temperature is 45~55℃ and the time is 35~60℃min.

7. The method for efficient decolorization, iron removal, and activation of waste textiles according to claim 1 or 2, characterized in that, The alkaline substance in the decolorizing solution is at least one of organic amine bases, sodium silicate, magnesium hydroxide, sodium hydroxide, and sodium carbonate. The decolorizing agent in the decolorizing solution is at least one of peracetic acid, persulfate, and percarbonate.

8. The method for efficient decolorization, iron removal, and activation of waste textiles according to claim 1 or 2, characterized in that, The content of alkaline substances in the decolorizing solution is 20~30g / L, and the content of decolorizing agent is 10~25g / L.

9. The method for efficient decolorization, iron removal, and activation of waste textiles according to claim 1 or 2, characterized in that, The decolorization process takes 40-70 minutes.

10. The method for efficient decolorization, iron removal, and activation of waste textiles according to claim 1 or 2, characterized in that, The method includes the following specific steps: S1, Decolorization treatment Add alkaline substances and decolorizing agents to water, mix well, and prepare a decolorizing solution with an alkaline substance content of 20~30g / L and a decolorizing agent content of 10~25g / L; Take waste textiles and perform preliminary cleaning to remove surface contaminants and grease; At room temperature, the washed waste textiles are placed in a decolorizing solution with a liquor ratio of 1:20~40. The temperature is then increased from room temperature to 30℃ at a rate of less than 2℃ / min, and then increased from 30℃ to 30~55℃ at a rate of less than 1.5℃ / min. The decolorization reaction is carried out at 30~55℃ for 40~70 minutes. After the decolorization is completed, the solid and liquid are separated to obtain decolorized fibers. S2, Iron removal treatment Preparation of pickling solution: Add polyethylene glycol to the acid solution and mix well to form a pickling solution with a polyethylene glycol content of 1~3 g / L and an acid content of 8~15 g / L; Pickling treatment: Place the decolorized fibers in the pickling solution and pickle at 45~55℃ for 35~60℃ min; Pickling solution recovery: After pickling is complete, solid and liquid are separated to obtain the treated textiles; The liquid obtained from solid-liquid separation is returned to the pickling process and recycled as pickling solution 3-5 times, with 10-20% fresh pickling solution added each time.