Bi-component decolorizing agent for polyester textiles and pretreatment method for recycling polyester textiles

Abstract

The invention belongs to the technical field of textile decolorizing treatment, and particularly relates to a bi-component decolorizing agent for polyester textiles and a pretreatment method for polyester textile recycling, the bi-component decolorizing agent comprises a component I and a component II according to the mass ratio of 1: 2.2-3, the component I comprises a sodium hydroxide solution and sodium borohydride, and the component II comprises a sodium hydroxide solution and sodium borohydride. The component II comprises sodium pyrosulfite and sodium sulfite, sodium borohydride is used for reacting with sodium pyrosulfite and sodium sulfite in a strong alkaline environment to generate an intermediate product with strong reducibility to remove organic dye molecules on the textile, and the decolorizing agent can be suitable for decolorizing and recycling of the polyester textile.

Description

Technical Field

[0001] The invention belongs to the technical field of textile decolorization treatment, and in particular relates to a two-component decolorizer for polyester textiles and a pretreatment method for recycling polyester textiles. Background Art

[0002] Every year, a large number of dyed textiles with a full range of varieties and bright colors are recycled and reused. A very important step in recycling is to bleach the textiles and remove the dyes on the fabrics to avoid chemical dyes affecting subsequent processing.

[0003] Existing textile decolorization methods include physical methods, chemical methods and biological methods. The physical method uses special organic solvents or surfactants to dissolve and remove dye molecules due to their affinity for dye molecules. The chemical method uses oxidants or reductants to decompose dye molecules to decolorize them. The biological method mainly uses various biological enzymes to catalyze the decomposition of dye molecules to decolorize them. At present, the chemical method has become the most common decolorization method due to its simple decolorization method and low decolorization cost.

[0004] For example, the chemical reagents commonly used in the prior art include hydrosulfur powder, thiourea dioxide, hydrogen peroxide, sodium hypochlorite, etc., but these chemical reagents also have many limitations and problems. For example, the chemical properties of hydrosulfur powder are active, it is very easy to decompose under hot and humid conditions and it will explode naturally under extreme conditions. The production equipment control cost is high, and due to its rapid reaction, it is easy to have incomplete decolorization; sodium hypochlorite is easy to produce chlorine during use, which is extremely harmful to the environment, workers and equipment; hydrogen peroxide has poor stability and general decolorization effect. Therefore, it is particularly important to study a new decolorization reagent with stable properties, good decolorization effect, safety and environmental protection. Summary of the invention

[0005] In view of the problems existing in the existing polyester textile decolorizing agents mentioned in the above-mentioned prior art, the present invention provides a two-component decolorizing agent for polyester textiles and a pretreatment method for recycling polyester textiles. Sodium borohydride is used to react with sodium pyrosulfite and sodium sulfite in a strong alkaline environment to produce a strongly reducing intermediate product to remove organic dye molecules on the textiles. Compared with the existing decolorizing agents, the decolorizing effect is better, the reaction conditions are mild and the pollution is small.

[0006] First, the present invention provides a two-component decolorizing agent for polyester textiles, comprising component I and component II in a mass ratio of 1:(2.2-3), wherein component I comprises sodium hydroxide solution and sodium borohydride, wherein the pH value of the sodium hydroxide solution in component I is 13-14, the mass ratio of the sodium borohydride to the sodium hydroxide solution is (1-2):1000, and component II comprises sodium pyrosulfite and sodium sulfite.

[0007] Furthermore, the mass ratio of sodium metabisulfite to sodium sulfite in the component II is 100:(1-3).

[0008] The present invention also provides a recycling pretreatment method for polyester textiles, comprising the following steps:

[0009] Step 1: Steam the polyester textiles to be recycled in water, then take them out and dry them;

[0010] Step 2: placing the dried polyester textile in a kettle containing the peregrine solution and soaking it;

[0011] Step 3: First add component I of the two-component decolorizer to the polyester textile soaked in step 2, stir and mix, then heat to the reaction temperature, add component II after the reaction temperature stabilizes, keep stirring during the addition process, the amount of component I in the two-component decolorizer is 1% to 2% of the mass of the polyester textile, then heat and stir to react and decolorize

[0012] Step 4: Wash and drain the decolorized polyester textile, add ethylene glycol and a catalyst to it for alcoholysis reaction, and recrystallize the mixture after the reaction to collect the product.

[0013] Furthermore, in the step 1, the polyester textile is steamed at a temperature of 90 to 100° C. and for a time of 15 to 30 minutes.

[0014] Furthermore, in the step 2, the concentration of the peregrine O solution is 0.2-0.4 g / L, the mass ratio of the amount of peregrine O added to the amount of polyester textile added is (1-2):100; and the immersion time is 10-15 min.

[0015] Furthermore, in the step three, the reaction temperature is 90-100° C., and the decolorization reaction time is 5-15 min.

[0016] Furthermore, the step four includes the following steps: mixing ethylene glycol and a catalyst in proportion and heating to boiling, then adding the polyester textile thereto and stirring for reaction; filtering and collecting the mixed solution after the polyester textile is dissolved, adding a magnetic decantation to separate the catalyst, washing with hot water to remove impurities, and then refrigerating and recrystallizing at low temperature to obtain a polyester monomer.

[0017] Furthermore, the catalyst is added in an amount of 0.8-1% by weight of the polyester textile, and the ethylene glycol is added in an amount of 200-250% by weight of the polyester textile.

[0018] Furthermore, the catalyst is zinc acetate.

[0019] Beneficial effects of the present invention:

[0020] 1. The present invention adopts a two-component decolorizing agent, and utilizes sodium borohydride and sodium pyrosulfite to react to generate a highly reducing intermediate product S2O4 2- , and by adding sodium sulfite to increase the reaction activity and reaction intensity, it can quickly destroy dye molecules with azo structure and anthraquinone structure, so that polyester textiles can be decolorized in 5 to 15 minutes without producing new decolorization products, greatly improving the decolorization efficiency of polyester textiles. At the same time, because it is a two-component formula, component I and component II are stored separately before use, and only react when mixed. Compared with other decolorizers, it is easy to store and can be prepared and used immediately, and the reaction process is mild, and no toxic or harmful gases are produced.

[0021] 2. In the present invention, a two-component decolorizing agent is used in the pretreatment of polyester textile recycling. After the polyester textile is first decolorized, the waste polyester textile is dissolved by an alcoholysis process and then purified and recycled. At the same time, through the dual effects of the two-component decolorizing agent and the catalyst, the decolorization rate of the polyester textile can be maintained at more than 95%, and the recovery rate of polyester can reach more than 90%, which can greatly improve the recycling rate of polyester textiles.

[0022] 3. The method of the present application is used to decolorize and recycle waste polyester textiles, and chemical reactions are used to destroy the molecular structure of organic dyes in polyester textiles. Without generating new colored substances, it is possible to ensure that the polyester monomers recovered after decolorization of the polyester textiles have good whiteness, so that the recovered products do not need to be bleached or decolorized and can be reproduced and reused. DETAILED DESCRIPTION

[0023] The specific scheme of the present invention is shown below through specific examples. These examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. The experimental methods without specific conditions in the examples are all based on conventional conditions. The amount of reagents used in the examples is only exemplary, and those skilled in the art can make corresponding adjustments according to actual conditions. The reagents can be obtained from commercial channels unless otherwise specified. The polyester textiles treated in the present invention are from Zhejiang Furun Recycling Resources Co., Ltd.

[0024] Example 1

[0025] First, this embodiment provides a two-component decolorizing agent for polyester textiles, including component I and component II. Component I includes sodium hydroxide solution and sodium borohydride, and component II includes sodium pyrosulfite and sodium sulfite. In the specific preparation scheme, 1000g of sodium hydroxide solution with a pH of 13 is taken, 1.5g of sodium borohydride is added thereto, and component I is prepared by mixing evenly. Then 2600g of sodium pyrosulfite and 2.6g of sodium sulfite are taken and mixed evenly to prepare component II. When using, component I and component II are added to the polyester textile in sequence.

[0026] This embodiment also provides a pretreatment method for recycling polyester textiles, using the above-mentioned two-component decolorizing agent to treat the polyester textiles to be recycled, specifically comprising the following steps:

[0027] Step 1: Steam the polyester textiles to be recycled in water, then take them out and dry them;

[0028] Specifically, 100 kg of polyester textiles to be recycled are weighed, placed in a heating kettle, water is added thereto, and the water temperature is heated to 90°C to steam the polyester textiles for 20 minutes to remove impurities on the polyester textiles and destroy the protective oil layer on the surface of the polyester textiles. After steaming, the polyester textiles are taken out and the water is drained.

[0029] Step 2: placing the dried polyester textile in a kettle containing the peregrine solution and soaking it;

[0030] Specifically, the polyester textile treated in step 1 is transferred to a stirring tank, 500 L of a 0.2 g / L solution of peregal O at a pH of 4 is added thereto, and the polyester textile is soaked for 10 minutes after stirring and mixing. The peregal O solution used in this embodiment is purchased from Peregal O-15 produced by Nantong Yixun Chemical Co., Ltd.

[0031] Step 3: first add component I of the two-component decolorizing agent to the polyester textile soaked in step 2, stir and mix, then heat to the reaction temperature, add component II after the reaction temperature stabilizes, keep stirring during the addition process, the amount of component I in the two-component decolorizing agent is 1% of the mass of the polyester textile, then heat and stir to react and decolorize;

[0032] Specifically, after the prepared two-component decolorizing agent component I and component II are mixed evenly, component I is first poured into a stirring kettle, stirring and heating are started, and after the temperature is heated to 90° C., component II is added to the stirring kettle, and the stirring reaction is maintained for 5 minutes for decolorization.

[0033] Step 4: Wash and drain the decolorized polyester textile, add ethylene glycol and a catalyst to it for alcoholysis reaction, and recrystallize the mixture after the reaction to collect the product.

[0034] Specifically, the polyester textile treated in step 3 is rinsed with hot water several times, drained, and then placed in an alcoholysis kettle and chopped. Take 220L of ethylene glycol, add 1kg of catalyst to the ethylene glycol, mix well, and heat to boiling, then add the boiling ethylene glycol catalyst mixed solution to the alcoholysis kettle, start stirring and heat-keeping reaction until the polyester textile is completely dissolved. After dissolution, quickly filter and collect the filtrate, separate the catalyst in the filtrate by magnetic decantation, and use boiling water to wash the filtrate to remove impurities in the filtrate. Finally, the filtrate is placed in a 4°C environment for cold recrystallization to obtain the recovered polyester monomer.

[0035] Example 2

[0036] The difference between this embodiment and embodiment 1 is that the pH of the sodium hydroxide solution in component I of the two-component decolorizer is 14. When preparing the solution, 1000 g of sodium hydroxide solution with a pH of 14 is taken, 1.5 g of sodium borohydride is added thereto, and the mixture is mixed evenly to form component I. Then 2600 g of sodium pyrosulfite and 2.6 g of sodium sulfite are taken and mixed evenly to form component II. When used, component I and component II are added to the polyester textile in sequence. The other experimental steps and experimental parameters are consistent with those of embodiment 1.

[0037] Example 3

[0038] The difference between this embodiment and embodiment 1 is that the amount of component I used in the two-component decolorizing agent is 2% of the mass of the polyester textile, and the other experimental steps and experimental parameters are consistent with those of embodiment 1.

[0039] In the specific implementation, 50 kg of polyester textiles to be recycled are weighed, placed in a heating kettle, water is added thereto, and the water temperature is heated to 90°C to steam the polyester textiles for 20 minutes to remove impurities on the polyester textiles and destroy the protective oil layer on the surface of the polyester textiles. After steaming, the polyester textiles are taken out and the water is drained.

[0040] The polyester textile treated in step 1 is transferred to a stirred tank, 500 L of 0.2 g / L peregrine O solution is added thereto, and the polyester textile is soaked for 10 minutes after stirring and mixing;

[0041] After mixing the above-prepared two-component decolorizing agent component I and component II respectively, first pour component I into the stirring kettle and start stirring and heating. After the temperature reaches 90°C, add component II into the stirring kettle and keep stirring for 5 minutes to decolorize.

[0042] Rinse the polyester textile treated in step 3 with hot water several times, drain the water, and then cut it into pieces in an alcoholysis kettle. Take 220L of ethylene glycol, add 1kg of catalyst to the ethylene glycol, mix well, and heat to boiling. Then add the boiling ethylene glycol catalyst mixed solution to the alcoholysis kettle, start stirring and keep warm to react until the polyester textile is completely dissolved. After dissolution, quickly filter and collect the filtrate, separate the catalyst in the filtrate by magnetic decantation, and use boiling water to wash the filtrate to remove impurities in the filtrate. Finally, place the filtrate in a 4°C environment and cool it for recrystallization to obtain the recovered polyester monomer.

[0043] Example 4

[0044] The difference between this embodiment and embodiment 1 is that the mass ratio of sodium metabisulfite to sodium sulfite in component II of the two-component decolorizing agent is 100:2, and the other experimental steps and experimental parameters are consistent with those of embodiment 1. In the specific preparation scheme, 1000g of sodium hydroxide solution with a pH of 13 is taken, 1.5g of sodium borohydride is added thereto, and the mixture is mixed evenly to form component I. Then 2600g of sodium metabisulfite and 5.2g of sodium sulfite are taken and mixed evenly to form component II. When used, component I and component II are added to the polyester textile in sequence.

[0045] Example 5

[0046] The difference between this embodiment and embodiment 1 is that the mass ratio of component I to component II in the two-component decolorizing agent is 1:3, and the other experimental steps and experimental parameters are consistent with those of embodiment 1. In the specific preparation scheme, 1000g of sodium hydroxide solution with a pH of 13 is taken, 1.5g of sodium borohydride is added thereto, and mixed evenly to form component I. Then 3000g of sodium pyrosulfite and 3g of sodium sulfite are taken and mixed evenly to form component II. When used, component I and component II are added to the polyester textile in sequence.

[0047] Example 6

[0048] The difference between this embodiment and embodiment 1 is that the mass ratio of component I to component II in the two-component decolorizing agent is 1:2.2, and the other experimental steps and experimental parameters are consistent with those of embodiment 1. In the specific preparation scheme, 1000g of sodium hydroxide solution with a pH of 13 is taken, 1.5g of sodium borohydride is added thereto, and mixed evenly to form component I. Then 2200g of sodium pyrosulfite and 2.2g of sodium sulfite are taken and mixed evenly to form component II. When used, component I and component II are added to the polyester textile in sequence.

[0049] Comparative Example 1

[0050] The difference between this comparative example and Example 1 is that the pH of the sodium hydroxide solution in component I is 12, and the other experimental steps and experimental parameters are consistent with those in Example 1. In the specific preparation scheme, 1000g of sodium hydroxide solution with a pH of 12 is taken, 1.5g of sodium borohydride is added thereto, and mixed evenly to prepare component I. Then 2600g of sodium pyrosulfite and 2.6g of sodium sulfite are taken and mixed evenly to prepare component II. When used, component I and component II are added to the polyester textile in sequence.

[0051] Comparative Example 2

[0052] The difference between this comparative example and Example 1 is that the amount of component I used in the two-component decolorizing agent is 3% of the mass of the polyester textile, and the other experimental steps and experimental parameters are consistent with those of Example 1.

[0053] In the specific implementation, 33 kg of polyester textiles to be recycled are weighed, placed in a heating kettle, water is added to the kettle, and the water temperature is heated to 90°C to steam the polyester textiles for 20 minutes to remove impurities on the polyester textiles and destroy the protective oil layer on the surface of the polyester textiles. After steaming, the polyester textiles are taken out and the water is drained.

[0054] The polyester textile treated in step 1 is transferred to a stirred tank, 500 L of 0.2 g / L peregrine O solution is added thereto, and the polyester textile is soaked for 10 minutes after stirring and mixing;

[0055] After mixing the above-prepared two-component decolorizing agent component I and component II respectively, first pour component I into the stirring kettle and start stirring and heating. After the temperature reaches 90°C, add component II into the stirring kettle and keep stirring for 5 minutes to decolorize.

[0056] Rinse the polyester textile treated in step 3 with hot water several times, drain the water, and then cut it into pieces in an alcoholysis kettle. Take 220L of ethylene glycol, add 1kg of catalyst to the ethylene glycol, mix well, and heat to boiling. Then add the boiling ethylene glycol catalyst mixed solution to the alcoholysis kettle, start stirring and keep warm to react until the polyester textile is completely dissolved. After dissolution, quickly filter and collect the filtrate, separate the catalyst in the filtrate by magnetic decantation, and use boiling water to wash the filtrate to remove impurities in the filtrate. Finally, place the filtrate in a 4°C environment and cool it for recrystallization to obtain the recovered polyester monomer.

[0057] Comparative Example 3

[0058] The difference between this comparative example and Example 1 is that sodium sulfite is not added to component II of the two-component decolorizing agent, and the other experimental steps and experimental parameters are consistent with those of Example 1. In the specific preparation scheme, 1000g of sodium hydroxide solution with a pH of 13 is taken, 1.5g of sodium borohydride is added thereto, and mixed evenly to prepare component I. Then 2600g of sodium pyrosulfite is taken as component II. When used, component I and component II are added to the polyester textile in sequence.

[0059] Comparative Example 4

[0060] The difference between this comparative example and Example 1 is that the mass ratio of component I to component II in the two-component decolorizer is 1:3.5, and the other experimental steps and experimental parameters are consistent with Example 1. In the specific preparation scheme, 1000g of sodium hydroxide solution with a pH of 13 is taken, 1.5g of sodium borohydride is added thereto, and mixed evenly to prepare component I. Then 3500g of sodium pyrosulfite and 3.5g of sodium sulfite are taken and mixed evenly to prepare component II. When used, component I and component II are added to the polyester textile in sequence.

[0061] Comparative Example 5

[0062] The difference between this comparative example and Example 1 is that the mass ratio of component I to component II in the two-component decolorizer is 1:2, and the other experimental steps and experimental parameters are consistent with Example 1. In the specific preparation scheme, 1000g of sodium hydroxide solution with a pH of 13 is taken, 1.5g of sodium borohydride is added thereto, and mixed evenly to prepare component I. Then 2000g of sodium pyrosulfite and 2g of sodium sulfite are taken and mixed evenly to prepare component II. When used, component I and component II are added to the polyester textile in sequence.

[0063] Comparative Example 6

[0064] The difference between this comparative example and Example 1 is that the mass ratio of sodium borohydride to sodium hydroxide solution in component I of the two-component decolorizer is 0.5:1000, and the other experimental steps and experimental parameters are consistent with those of Example 1. In the specific preparation scheme, 1000g of sodium hydroxide solution with a pH of 13 is taken, 0.5g of sodium borohydride is added thereto, and mixed evenly to prepare component I. Then 2600g of sodium pyrosulfite and 2.6g of sodium sulfite are taken and mixed evenly to prepare component II. When used, component I and component II are added to the polyester textile in sequence.

[0065] Comparative Example 7

[0066] The difference between this comparative example and Example 1 is that the step 3 in the preparation method is different, specifically, the two-component decolorizing agent prepared above is mixed evenly and poured into a stirring kettle, and the stirring and heating are started, and the heating temperature is heated to 90° C. and reacted for 5 minutes for decolorization.

[0067] The preparation methods and application environment parameters of the two-component decolorizing agents prepared in the above examples and comparative examples are statistically shown in Table 1 below.

[0068] The decolorization rate and color difference of the polyester textiles treated in the above examples and comparative examples were tested after decolorization. The test results are shown in Table 2 below. Decolorization rate detection method: A spectrophotometer (such as UltraScan Pro) was used to measure the decolorization rate of the polyester textiles at D 65 The K / S value of polyester textiles before and after decolorization was measured under light source and 10° viewing angle. Each group of samples was measured 5 times to take the average value, and the decolorization rate was calculated according to the following formula:

[0069] in is the K / S value of polyester textiles before bleaching, It is the K / S value of polyester textile after bleaching.

[0070] Testing method for strength retention rate: Test the breaking strength of polyester textiles before and after bleaching in accordance with the textile breaking strength test method in GB / T 3923.1-2013, and calculate the strength retention rate according to the following formula:

[0071] Among them, F1 is the breaking strength value of polyester textile after bleaching, and F2 is the breaking strength value of polyester textile before bleaching.

[0072] The color value test is expressed using the L*a*b color table, where L * Indicates the brightness of the product, a * and b * Indicates the red-green and yellow-blue states of textiles. In the present invention, a colorimeter (CR-300 type) is used to test the color value.

[0073] Table 1: Statistical table of experimental parameters of embodiments and comparative examples

[0074]

[0075] Table 2: Statistical table of experimental results of embodiments and comparative examples

[0076]

[0077] Experimental results analysis:

[0078] From the analysis of the above experimental results, it can be seen that the decolorization rate of the treated product can reach more than 95% by using the two-component decolorizing agent provided by the present invention to treat waste polyester textiles, and the strong retention rate can also be maintained at about 95% or even higher, indicating that this method can effectively remove the color on polyester textiles without affecting the structure of polyester materials, and is very suitable for decolorization of polyester textiles. At the same time, after the polyester textiles are recycled and pre-treated, the color value of the recycled polyester textiles is checked after decolorization. * The value shows that the product after pretreatment has a higher brightness, and a * and b * All of them are close to 0, indicating that the polyester textile after decolorization is close to white. Finally, when the polyester monomer is recovered after pretreatment, the loss rate of the polyester textile pretreated by the embodiment of the present invention is calculated to be about 3.9%, which meets the recycling requirements of the product.

[0079] In Comparative Example 1, when the pH value of sodium hydroxide in component I was changed, the decolorization effect of the polyester textile was reduced, wherein the decolorization rate dropped to about 90%, and the color value of the polyester textile after decolorization was also significantly reduced compared with the embodiment. The reason is that when the alkalinity is increased, the reaction of sodium borohydride and sodium metabisulfite will be promoted in the forward direction, thereby producing more decolorization intermediates.

[0080] In Comparative Example 2, when the amount of component I was increased, the experimental results showed that although the decolorization effect on polyester textiles was enhanced, the strong retention rate of the decolorized polyester textiles decreased, indicating that the structure of polyester would be destroyed under excessive alkalinity and the use of sodium borohydride. At the same time, through calculation, the loss rate of polyester textiles after pretreatment reached about 9%, so it is not suitable for recycling pretreatment of polyester textiles.

[0081] In Comparative Example 3, no sodium sulfite was added. From the experimental results, the decolorization effect was significantly weaker than that of the technical solution of the embodiment of the present invention under the same action time. The reason is that the addition of sodium sulfite can significantly increase the reaction rate of sodium borohydride and sodium pyrosulfite, and accelerate the reaction to proceed in the forward direction.

[0082] In Comparative Examples 4-5, when the ratio of component I and component II was changed, the decolorization effect of the two-component decolorizer was greatly reduced. The reason is that if the proportion of component II is increased, its hydrolysis degree is increased, thereby reducing the reaction effect. When the proportion of component I is large, its decolorization effect on anthraquinone dyes will be significantly reduced, thereby reducing the overall decolorization effect.

[0083] In Comparative Example 7, when the order of adding component I and component II is changed, the experimental results show that the decolorization effect will also decrease. The reason is that adding component I to the polyester textile first can utilize the strong reactivity of sodium borohydride in component I to decolorize the dye first, and then adding sodium pyrosulfite and sodium sulfite can react with sodium borohydride to produce stronger decolorization intermediates, and at the same time, they themselves have a certain removal effect on anthraquinone dyes, further enhancing the decolorization effect.

[0084] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view. In addition, it should be understood that although this specification is described in accordance with the embodiments, it does not contain only one technical solution. This narrative of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A two-component decolorizing agent for polyester textiles, characterized in that: The invention comprises component I and component II in a mass ratio of 1:(2.2-3), wherein component I comprises sodium hydroxide solution and sodium borohydride, the pH value of the sodium hydroxide solution in component I is 13-14, the mass ratio of the sodium borohydride to the sodium hydroxide solution is (1-2):1000, and component II comprises sodium pyrosulfite and sodium sulfite.

2. A two-component decolorizing agent for polyester textiles according to claim 1, characterized in that: The mass ratio of sodium metabisulfite to sodium sulfite in the component II is 100:(1-3).

3. A pretreatment method for recycling polyester textiles, characterized in that: Using the two-component decolorizing agent according to any one of claims 1 to 2 and comprising the following steps: Step 1: Steam the polyester textiles to be recycled in water, then take them out and dry them; Step 2: placing the dried polyester textile in a kettle containing the peregrine solution and soaking it; Step 3: first add component I of the two-component decolorizing agent to the polyester textile soaked in step 2, stir and mix, then heat to the reaction temperature, add component II after the reaction temperature stabilizes, keep stirring during the addition process, the amount of component I in the two-component decolorizing agent is 1% to 2% of the mass of the polyester textile, then heat and stir to react and decolorize; Step 4: Wash and drain the decolorized polyester textile, add ethylene glycol and a catalyst to it for alcoholysis reaction, and recrystallize the mixture after the reaction to collect the product.

4. A pretreatment method for recycling polyester textiles according to claim 3, characterized in that: In the step 1, the polyester textile is boiled at a temperature of 90 to 100° C. and for a time of 15 to 30 minutes.

5. A pretreatment method for recycling polyester textiles according to claim 3, characterized in that: In the step 2, the concentration of the peregrine O solution is 0.2-0.4 g / L, and the mass ratio of the peregrine O to the polyester textile addition is (1-2):100; the soaking time is 10-15 min.

6. A pretreatment method for recycling polyester textiles according to claim 5, characterized in that: The reaction temperature is 90-100° C., and the decolorization reaction time is 5-15 minutes.

7. A pretreatment method for recycling polyester textiles according to claim 3, characterized in that: The step 4 comprises the following steps: mixing ethylene glycol and a catalyst in proportion and heating to boiling, then adding the polyester textile and stirring for reaction; filtering and collecting the mixed solution after the polyester textile is dissolved, separating the catalyst by magnetic decantation, washing with hot water to remove impurities, and then refrigerating and recrystallizing to obtain a polyester monomer.

8. A pretreatment method for recycling polyester textiles according to claim 7, characterized in that: The catalyst is zinc acetate, the added amount of the catalyst is 0.8-1% of the weight of the polyester textile, and the added amount of the ethylene glycol is 200-250% of the weight of the polyester textile.

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