Biochar catalyst based on waste cotton fabric, preparation method and application

Abstract

The invention relates to the technical field of biochar catalysts, in particular to a biochar catalyst based on waste cotton fabrics as well as a preparation method and application of the biochar catalyst based on the waste cotton fabrics. The waste cotton fabrics are used as raw materials and are wide in source and low in cost, the recycling rate of the waste cotton fabrics can be increased, and the additional value of the waste cotton fabrics can be increased; compared with a monometal catalyst, the biomass charcoal bimetallic catalyst prepared by the technical scheme has more advantages in the catalytic process: bimetallic components have a synergistic effect, so that the catalytic activity and selectivity are improved; compared with a monometal catalyst, the bimetallic catalyst has higher stability and poisoning resistance, meanwhile, the biomass charcoal bimetallic catalyst prepared by the technical scheme has a high specific surface area similar to that of activated carbon, pollutants and an oxidizing agent in sewage can be effectively enriched, the concentration of a substrate on the surface of the catalyst is increased, and the catalytic activity of the catalyst is improved. The advanced oxidation reaction efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of biochar catalysts, and in particular to a biochar catalyst based on waste cotton fabrics, a preparation method and an application thereof. Background Art

[0002] In recent years, advanced oxidation technology based on persulfate has attracted wide attention in sewage treatment due to its strong oxidation ability, high degradation efficiency, mild operating conditions, and short reaction time. However, the direct oxidation reaction efficiency of pollutants by persulfate is low, and it needs to be activated by a catalyst to produce sulfate radicals or other active oxygen species with strong oxidizing properties in order to achieve efficient degradation of pollutants. Biochar material is a heterogeneous catalyst carrier widely used in the field of water pollution control, and waste cotton fabric has a high carbon content (40% to 50%), which is an ideal biochar precursor. It can be effectively converted into a biochar material with high activity and high specific surface area through high-temperature carbonization, solvent thermal method, supercritical water treatment and other methods, and further prepared into a transition metal-loaded catalyst for activating persulfate to degrade difficult-to-treat emerging pollutants.

[0003] 1. Therefore, a high-performance activated carbon microsphere is proposed in the prior art (application number CN202311817279.8), and the activated carbon microsphere specifically includes the following preparation steps:

[0004] 1. Wash the waste cotton fabric several times with distilled water, dry it in an oven at 80℃ for 12h, and then cut the waste cotton fabric into small pieces of 0.5*0.5cm;

[0005] 2. Place a small piece of waste cotton fabric into the polytetrafluoroethylene lining of the reactor and add 100 ml of 6-10 wt% ZnCl2 solution;

[0006] 3. Tighten the high-pressure reactor and place it in a forced air drying oven at 180-200°C for hydrothermal carbonization for 6 hours. The obtained powder is repeatedly washed with deionized water and dried in an oven for 12 hours.

[0007] 4. The obtained product was placed in an inert atmosphere tubular furnace and heated to 800-900°C for 2 hours. After natural cooling, high-performance activated carbon microspheres were obtained.

[0008] Second, the prior art also proposes an iron-copper bimetallic biochar material based on waste cotton fabric (application number CN202110263116.4), and its preparation process is as follows:

[0009] 1. After washing the waste cotton fabric with pure water, dry it and cut it into pieces with a side length of about 5 mm;

[0010] 2. 10 g of shredded waste cotton fabric was heated to a certain temperature (400-800 °C) in a tube furnace at 10 °C / min for 1 h, named BC;

[0011] 3. A certain amount (4.5–13 g) of BC was mixed with 50 mL of 0.3 mol / L sodium oxalate solution and heated to 60 °C in a water bath. Then, 50 mL of 0.15 mol / L FeSO was added dropwise at a rate of 5 mL / min. 4 .7H 2 O and 0.15 mol / LCuSO 4 .5H 2 O mixed solution. After mixing for 30 min, a yellow-green precipitate was separated and dried;

[0012] 4. The obtained product is pyrolyzed at a certain temperature (350-500°C) for 4 hours and passed through a 100-mesh sieve to obtain an iron-copper bimetallic biochar material.

[0013] However, the product obtained in the prior art one is a single metal activated carbon, which has poor stability as a catalyst and is prone to problems such as catalyst poisoning and active component flow, which in turn affects the use effect and life of the catalyst. The chemical precipitation method used in the prior art two to load the transition metal has the problems of uneven and unstable metal distribution, resulting in unsatisfactory catalytic effect. Summary of the invention

[0014] The purpose of the present invention is to provide a biochar catalyst based on waste cotton fabrics, a preparation method and an application thereof, so as to solve the problem that the product obtained in the prior art one is a single metal activated carbon, which has poor stability as a catalyst, is prone to catalyst poisoning and active component flow, thereby affecting the use effect and life of the catalyst; and the chemical precipitation method used in the prior art two to load transition metals has the problems of uneven metal distribution and looseness, resulting in unsatisfactory catalytic effect.

[0015] To achieve the above object, the present invention provides a method for preparing a biochar catalyst based on waste cotton fabrics, and the method for preparing a biochar catalyst based on waste cotton fabrics comprises the following steps:

[0016] Cut the waste cotton fabric into pieces with a side length of 2-10 mm, put them into a beaker containing 500 mL of deionized water, stir and wash them, and dry them in a drying oven for later use;

[0017] At room temperature, weighing preset masses of two transition metal chlorides / sulfates respectively, dissolving them in preset volumes of ethanol respectively, ensuring that their respective final concentrations are 1 mol / L, to prepare metal solutions;

[0018] Weigh 10 g of dried cotton fabric fragments, ultrasonically disperse them in a mixed solution of ethanol and water with a preset volume, and dropwise add a preset volume of metal solution to obtain a hydrothermal reaction solution with uniform solute distribution;

[0019] The obtained hydrothermal reaction solution was transferred to a polytetrafluoroethylene hydrothermal reactor, and reacted at a temperature of 250-350°C for 4-8 hours. After the reaction was completed, it was naturally cooled to room temperature, and the obtained product was washed with ethanol and deionized water respectively, and the product was dried in a drying oven at 60°C to constant weight to obtain a semi-finished product material;

[0020] The obtained semi-finished product material is transferred to a quartz boat, placed in a tubular furnace, and calcined at a high temperature of 300-600°C under nitrogen protection. After natural cooling, a highly active biomass carbon bimetallic catalyst is obtained.

[0021] Among them, in the step of "cutting the waste cotton fabric into pieces with a side length of 2-10 mm, and putting them into a beaker containing 500 mL of deionized water for stirring and washing, and drying them in a drying oven for standby use after washing", the stirring speed of the stirring and washing is 300-500 rpm / min, the number of washing times is 3 times, and the drying temperature of the drying oven is 80°C.

[0022] In the step “At room temperature, weigh two transition metal chlorides / sulfates of preset masses, respectively dissolve them in preset volumes of ethanol, ensure that their respective final concentrations are 1 mol / L, and prepare metal solutions”, the transition metal chloride / sulfate is CuCl 2 ·2H 2 O / CuSO 4 ·5H 2 O, FeCl 2 / FeSO 4 7H 2 O、ZnCl 2 / ZnSO 4 ·H 2 O、CoCl 2 6H 2 O / CoSO 4 7H 2 O、NiCl 2 6H 2 O / NiSO 4 6H 2 O and MnCl 2 ·4H 2 O / MnSO 4 ·H 2 One of O.

[0023] Among them, in the step of "weighing 10g of dried cotton fabric fragments, ultrasonically dispersing them in a mixed solution of a preset volume of ethanol and water, and dripping a preset volume of metal solution to obtain a hydrothermal reaction solution with a uniform solute distribution", the ultrasonic dispersion time is 10 minutes, and the conditions for dripping the metal solution are a total mass concentration of 1 to 5% and a molar ratio of the bimetallic ions of 3:1 to 1:3.

[0024] Among them, in the step of "transferring the obtained hydrothermal reaction solution to a polytetrafluoroethylene hydrothermal reactor, reacting at a temperature of 250-350°C for 4-8h, and after the reaction is completed, waiting for it to cool naturally to room temperature, washing the obtained product with ethanol and deionized water respectively, and drying the product in a 60°C drying oven to constant weight to obtain a semi-finished product material", the specific process of washing the obtained product with ethanol and deionized water is: first use 100mL of ethanol to disperse the product, stir and wash it 3 times, filter it, and then use 100mL of deionized water to stir and wash it 3 times to remove the ethanol on the surface of the product, and filter to obtain a solid product.

[0025] The present invention also provides a biochar catalyst, which is prepared by the above-mentioned method for preparing the biochar catalyst based on waste cotton fabric.

[0026] The present invention also provides an application of a biochar catalyst in a method for treating water of pollutants. To 100 mL of a solution containing pollutants, 2-10 mg of the biochar catalyst is added, and the concentration of persulfate is 0.05-0.5 mol / L, so as to achieve efficient removal of pollutants, wherein the concentration of the pollutants is 0.5-10 mg / L, the water temperature is 15-30°C, and the initial pH of the solution is 3-11.

[0027] The present invention discloses a biochar catalyst based on waste cotton fabric, a preparation method and an application thereof. The waste cotton fabric is used as a raw material, has a wide source and low cost, can improve the recycling rate of waste cotton fabric, and enhance the added value of waste cotton fabric. The biochar bimetallic catalyst prepared by the present technical scheme has more advantages than the single metal catalyst in the catalytic process: the bimetallic components have a synergistic effect, which improves the catalytic activity and selectivity; the bimetallic catalyst has higher stability and anti-poisoning ability than the single metal catalyst. At the same time, the biochar bimetallic catalyst prepared by the present technical scheme has a high specific surface area similar to that of activated carbon, can effectively enrich pollutants and oxidants in sewage, and increase the substrate concentration on the catalyst surface, thereby improving the efficiency of advanced oxidation reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 The present invention provides a flowchart of the steps of preparing a biochar catalyst based on waste cotton fabrics.

[0030] Figure 2 It is a ct curve diagram of the degradation of sulfamethoxazole by the FeMn@MFC / PMS system provided by the present invention.

[0031] Figure 3 It is a ct curve diagram of the degradation of sulfamethoxazole by the Mn@MFC / PMS system provided by the present invention.

[0032] Figure 4 It is a ct curve diagram of the degradation of sulfamethoxazole by the Fe@MFC / PMS system provided by the present invention.

[0033] Figure 5 It is a ct curve diagram of the degradation of sulfamethoxazole by the CuZn@MFC / PMS system provided by the present invention.

[0034] Figure 6 It is a ct curve diagram of the degradation of sulfamethoxazole by the Cu@MFC / PMS system provided by the present invention.

[0035] Figure 7 This is a ct curve diagram of the degradation of sulfamethoxazole by the Zn@MFC / PMS system provided by the present invention.

[0036] Figure 8 It is a comparison chart of the removal efficiency of sulfamethoxazole by the Cu@MFC / PMS, Zn@MFC / PMS and CuZn@MFC / PMS systems provided by the present invention.

[0037] Fig. 9 It is a comparison chart of the removal efficiency of sulfamethoxazole by the Cu@MFC / PMS, Zn@MFC / PMS and CuZn@MFC / PMS systems provided by the present invention.

[0038] Fig.10 This is a surface scanning analysis diagram of element distribution of CuZn@MFC provided by the present invention. DETAILED DESCRIPTION

[0039] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0040] See also Figures 1 to 10 The present invention provides a method for preparing a biochar catalyst based on waste cotton fabrics, and the method for preparing a biochar catalyst based on waste cotton fabrics comprises the following steps:

[0041] S1: Cut the waste cotton fabric into pieces with a side length of 2-10 mm, put them into a beaker containing 500 mL of deionized water, stir and wash them, and dry them in a drying oven for later use;

[0042] S2: At room temperature, weigh preset masses of two transition metal chlorides / sulfates respectively, and dissolve them in preset volumes of ethanol respectively to ensure that their respective final concentrations are 1 mol / L, to prepare metal solutions;

[0043] S3: Weigh 10 g of dried cotton fabric fragments, ultrasonically disperse them in a mixed solution of ethanol and water with a preset volume, and dropwise add a preset volume of a metal solution to obtain a hydrothermal reaction solution with a uniform solute distribution;

[0044] S4: transferring the obtained hydrothermal reaction solution to a polytetrafluoroethylene hydrothermal reactor, reacting at a temperature of 250-350°C for 4-8h, and after the reaction, allowing it to cool naturally to room temperature, washing the obtained product with ethanol and deionized water respectively, and drying the product in a drying oven at 60°C to constant weight to obtain a semi-finished product material;

[0045] S5: The obtained semi-finished product material is transferred to a quartz boat, placed in a tubular furnace, and calcined at a high temperature of 300-600°C under nitrogen protection. After natural cooling, a highly active biomass carbon bimetallic catalyst is obtained.

[0046] In this embodiment, waste cotton fabrics are used as raw materials, which have a wide source and low cost, can improve the recycling rate of waste cotton fabrics, and enhance the added value of waste cotton fabrics. The biomass carbon bimetallic catalyst prepared by this technical solution has more advantages than the single metal catalyst in the catalytic process: the bimetallic components have a synergistic effect, which improves the catalytic activity and selectivity; the bimetallic catalyst has higher stability and anti-poisoning ability than the single metal catalyst. At the same time, the biomass carbon bimetallic catalyst prepared by this technical solution has a high specific surface area similar to that of activated carbon, which can effectively enrich pollutants and oxidants in sewage, and increase the substrate concentration on the catalyst surface, thereby improving the efficiency of advanced oxidation reactions.

[0047] Furthermore, in the step of "cutting the waste cotton fabric into pieces with a side length of 2-10 mm, and putting them into a beaker containing 500 mL of deionized water for stirring and washing, and drying them in a drying oven for later use after washing", the stirring speed for stirring and washing is 300-500 rpm / min, the number of washing times is 3 times, and the drying temperature of the drying oven is 80°C.

[0048] Further, in the step of “at room temperature, weighing preset masses of two transition metal chlorides / sulfates respectively, dissolving them in preset volumes of ethanol respectively, ensuring that their respective final concentrations are 1 mol / L, and preparing metal solutions”, the transition metal chloride / sulfate is CuCl 2 ·2H 2 O / CuSO 4 ·5H 2 O, FeCl 2 / FeSO 4 7H 2 O、ZnCl 2 / ZnSO 4 ·H 2 O、CoCl 2 6H 2 O / CoSO 4 7H 2 O、NiCl 2 6H 2 O / NiSO 4 6H 2 O and MnCl 2 ·4H 2 O / MnSO 4 ·H 2 One of O.

[0049] Furthermore, in the step of "weighing 10 g of dried cotton fabric fragments, ultrasonically dispersing them in a mixed solution of a preset volume of ethanol and water, and dropping a preset volume of a metal solution to obtain a hydrothermal reaction solution with a uniform solute distribution", the ultrasonic dispersion time is 10 minutes, and the conditions for dropping the metal solution are a total mass concentration of 1 to 5% and a molar ratio of the bimetallic ions of 3:1 to 1:3.

[0050] Furthermore, in the step of “transferring the obtained hydrothermal reaction solution to a polytetrafluoroethylene hydrothermal reactor, reacting at a temperature of 250-350°C for 4-8h, and after the reaction is completed, allowing it to cool naturally to room temperature, washing the obtained product with ethanol and deionized water respectively, and drying the product in a 60°C drying oven to constant weight to obtain a semi-finished product material”, the specific process of washing the obtained product with ethanol and deionized water is: first use 100mL of ethanol to disperse the product, stir and wash it 3 times, filter it, and then use 100mL of deionized water to stir and wash it 3 times to remove the ethanol on the surface of the product, and filter it to obtain a solid product.

[0051] Embodiment 1:

[0052] The waste cotton fabric was cut into pieces with a side length of 5 mm, and placed in a beaker containing 500 mL of deionized water, washed three times at a stirring speed of 300 rpm / min, and dried in a drying oven at 80°C;

[0053] At room temperature, weigh 2.78 g of FeSO 4 7H 2 O and 1.69 g MnSO 4 ·H 2 O, respectively, and dissolved them in 10 mL of ethanol to obtain metal solutions;

[0054] Preparation of hydrothermal reaction solution: Weigh 10 g of the material from step 1) and ultrasonically disperse it in a mixed solution of 80 mL of ethanol and water (ethanol: water = 1:4), and then add a metal solution (FeSO 4 7H 2 O solution and MnSO 4 ·H 2 O solution, each 1 mL), and the resulting mixture was ultrasonically dispersed for 10 min to obtain a hydrothermal reaction solution with uniform solute distribution;

[0055] The obtained hydrothermal reaction solution was transferred to a 150 mL polytetrafluoroethylene hydrothermal reactor and reacted at 280° C. for 6 h. After the reaction was completed, the product was naturally cooled to room temperature, washed with ethanol and deionized water respectively, and dried in a drying oven at 60° C. to constant weight to obtain a semi-finished product.

[0056] The semi-finished product material was transferred to a quartz boat, placed in a tube furnace, and calcined at a high temperature of 350° C. under nitrogen protection, and naturally cooled to obtain a highly active biomass carbon iron manganese catalyst;

[0057] To 100 mL of 1 mg / L sulfamethoxazole solution, 10 mg of biomass carbon iron manganese catalyst (FeMn@MFC) was added, the concentration of persulfate was 0.1 mol / L, the water temperature was 15 °C, and the initial pH of the solution was 6.5. The removal efficiency of sulfamethoxazole was as follows: Figure 2 shown.

[0058] Comparative Example 1:

[0059] The waste cotton fabric was cut into pieces with a side length of 5 mm, and placed in a beaker containing 500 mL of deionized water, washed three times at a stirring speed of 300 rpm / min, and dried in a drying oven at 80°C;

[0060] At room temperature, weigh 1.69 g of MnSO 4 ·H 2 O or 2.78 g FeSO 4 7H 2 O, and dissolved it in 10 mL of ethanol to obtain MnSO 4 ·H 2 O solution or FeSO 4 7H 2 O solution;

[0061] Preparation of hydrothermal reaction solution: 10 g of dried cotton fabric fragments were weighed and ultrasonically dispersed in a mixed solution of 80 mL of ethanol and water (ethanol: water = 1:3), and the obtained MnSO 4 ·H 2 O solution or FeSO 4 7H 2 O1 mL, and the resulting mixture was ultrasonically dispersed for 10 min to obtain a hydrothermal reaction solution with uniform solute distribution;

[0062] The obtained hydrothermal reaction solution was transferred to a 150 mL polytetrafluoroethylene hydrothermal reactor and reacted at 280°C for 6 hours. After the reaction was completed, it was cooled naturally to room temperature, and the obtained product was washed with ethanol and deionized water respectively, and the product was dried in a drying oven at 60°C to constant weight to obtain a semi-finished product material;

[0063] The semi-finished product material was transferred to a quartz boat, placed in a tube furnace, and calcined at a high temperature of 350° C. under nitrogen protection, and then naturally cooled to obtain a biomass carbon manganese catalyst;

[0064] To 100 mL of 1 mg / L sulfamethoxazole solution, 10 mg of biomass carbon manganese catalyst (Mn@MFC) or biomass carbon iron catalyst (Fe@MFC) was added, the concentration of persulfate was 0.1 mol / L, the water temperature was 15 °C, and the initial pH of the solution was 6.5.

[0065] Among them, when the biochar catalyst is biomass carbon and the manganese catalyst is (Mn@MFC), the removal efficiency of sulfamethoxazole is as follows: Figure 3 shown.

[0066] Among them, when the biochar catalyst is biomass carbon iron catalyst (Fe@MFC), the removal efficiency of sulfamethoxazole is as follows: Figure 4 shown.

[0067] Embodiment 2:

[0068] The waste cotton fabric was cut into pieces with a side length of 5 mm, and placed in a beaker containing 500 mL of deionized water, washed three times at a stirring speed of 400 rpm / min, and dried in a drying oven at 80 °C;

[0069] At room temperature, weigh 1.25 g of CuSO 4 ·5H 2 O and 0.81 g ZnSO 4 ·H 2 O, respectively, and dissolved them in 5 mL of ethanol to prepare metal solutions;

[0070] Preparation of hydrothermal reaction solution: 10 g of dried cotton fabric fragments were weighed and ultrasonically dispersed in a mixed solution of 100 mL of ethanol and water (ethanol: water = 1:3), and a metal solution (CuSO 4 ·5H 2 O solution 1mL and ZnSO 4 ·H 2 O solution 2mL), and the resulting mixture was ultrasonically dispersed for 20min to obtain a hydrothermal reaction solution with uniform solute distribution;

[0071] The obtained hydrothermal reaction solution was transferred to a 150 mL polytetrafluoroethylene hydrothermal reactor and reacted at 250° C. for 8 h. After the reaction was completed, it was cooled naturally to room temperature, and the obtained product was washed with ethanol and deionized water respectively, and the product was dried in a drying oven at 60° C. to constant weight to obtain a semi-finished product material;

[0072] The semi-finished product obtained in the step is transferred to a quartz boat, placed in a tube furnace, and calcined at a high temperature of 400° C. under nitrogen protection, and naturally cooled to obtain a highly active biomass carbon copper-zinc catalyst;

[0073] To 100 mL of 0.8 mg / L sulfamethoxazole solution, 10 mg of biomass carbon copper zinc catalyst (CuZn@MFC) was added, the concentration of persulfate was 0.1 mol / L, the water temperature was 13 °C, and the initial pH of the solution was 6.5. The removal efficiency of sulfamethoxazole was as follows: Figure 5 shown.

[0074] Comparative Example 2:

[0075] The waste cotton fabric was cut into pieces with a side length of 5 mm, and placed in a beaker containing 500 mL of deionized water, washed three times at a stirring speed of 300-500 rpm / min, and dried in a drying oven at 80°C;

[0076] At room temperature, weigh 1.25 g of CuSO 4 ·5H 2 O or 0.81 g ZnSO 4 ·H 2 O, and dissolved it in 5 mL of ethanol to obtain CuSO 4 ·5H 2 O solution or ZnSO 4 ·H 2 O solution;

[0077] Preparation of hydrothermal reaction solution: 10 g of dried cotton fabric fragments were weighed and ultrasonically dispersed in a mixed solution of 100 mL of ethanol and water (ethanol: water = 1:3). CuSO 4 ·5H 2 O solution or ZnSO 4 ·H 2 O solution 1 mL, and the resulting mixture was ultrasonically dispersed for 20 min to obtain a hydrothermal reaction solution with uniform solute distribution;

[0078] The obtained mixed water thermal reaction solution was transferred to a 150 mL polytetrafluoroethylene hydrothermal reactor and reacted at a temperature of 250° C. for 8 h. After the reaction was completed, it was cooled naturally to room temperature, and the obtained product was washed with ethanol and deionized water respectively, and the product was dried in a drying oven at 60° C. to constant weight to obtain a semi-finished product material;

[0079] The semi-finished product material was transferred to a quartz boat, placed in a tube furnace, and calcined at a high temperature of 400° C. under nitrogen protection, and then naturally cooled to obtain a biomass carbon copper catalyst;

[0080] To 100 mL of 0.8 mg / L sulfamethoxazole solution, 10 mg of biomass carbon copper catalyst (Cu@MFC) or biomass carbon zinc catalyst (Zn@MFC) was added, the concentration of persulfate was 0.1 mol / L, the water temperature was 13 °C, and the initial pH of the solution was 6.5.

[0081] Among them, when the biochar catalyst is biomass carbon copper catalyst (Cu@MFC), the removal efficiency of sulfamethoxazole is as follows: Figure 6 shown.

[0082] Among them, when the biochar catalyst is biomass carbon zinc catalyst (Zn@MFC), the removal efficiency of sulfamethoxazole is as follows Figure 7 shown.

[0083] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for preparing a biochar catalyst based on waste cotton fabrics, characterized in that: The steps include: Cut the waste cotton fabric into pieces with a side length of 2-10 mm, put them into a beaker containing 500 mL of deionized water, stir and wash them, and dry them in a drying oven for later use; At room temperature, weighing preset masses of two transition metal chlorides / sulfates respectively, dissolving them in preset volumes of ethanol respectively, ensuring that their respective final concentrations are 1 mol / L, to prepare metal solutions; Weigh 10 g of dried cotton fabric fragments, ultrasonically disperse them in a mixed solution of ethanol and water with a preset volume, and dropwise add a preset volume of metal solution to obtain a hydrothermal reaction solution with uniform solute distribution; The obtained hydrothermal reaction solution was transferred to a polytetrafluoroethylene hydrothermal reactor, and reacted at a temperature of 250-350°C for 4-8 hours. After the reaction was completed, it was naturally cooled to room temperature, and the obtained product was washed with ethanol and deionized water respectively, and the product was dried in a drying oven at 60°C to constant weight to obtain a semi-finished product material; The obtained semi-finished product material is transferred to a quartz boat, placed in a tubular furnace, and calcined at a high temperature of 300-600°C under nitrogen protection. After natural cooling, a highly active biomass carbon bimetallic catalyst is obtained.

2. The method for preparing a biochar catalyst based on waste cotton fabric according to claim 1, characterized in that: In the step of "cutting the waste cotton fabric into pieces with a side length of 2-10 mm, putting them into a beaker containing 500 mL of deionized water, stirring and washing them, and drying them in a drying oven for standby use after washing", the stirring speed of the stirring and washing is 300-500 rpm / min, the number of washing times is 3 times, and the drying temperature of the drying oven is 80°C.

3. The method for preparing a biochar catalyst based on waste cotton fabric according to claim 2, characterized in that: In the step “at room temperature, weigh preset masses of two transition metal chlorides / sulfates respectively, dissolve them in preset volumes of ethanol respectively to ensure that their respective final concentrations are 1 mol / L to prepare metal solutions”, the transition metal chloride / sulfate is one of CuCl2·2H2O / CuSO4·5H2O, FeCl2 / FeSO4·7H2O, ZnCl2 / ZnSO4·H2O, CoCl2·6H2O / CoSO4·7H2O, NiCl2·6H2O / NiSO4·6H2O and MnCl2·4H2O / MnSO4·H2O.

4. The method for preparing a biochar catalyst based on waste cotton fabric according to claim 3, characterized in that: In the step of "weighing 10 g of dried cotton fabric fragments, ultrasonically dispersing them in a mixed solution of a preset volume of ethanol and water, and dripping a preset volume of a metal solution to obtain a hydrothermal reaction solution with a uniform solute distribution", the ultrasonic dispersion time is 10 minutes, and the conditions for dripping the metal solution are that the total mass concentration is 1 to 5% and the molar ratio of the bimetallic ions is between 3:1 and 1:

3.

5. The method for preparing a biochar catalyst based on waste cotton fabric according to claim 4, characterized in that: In the step "transferring the obtained hydrothermal reaction solution to a polytetrafluoroethylene hydrothermal reactor, reacting at a temperature of 250-350°C for 4-8h, and after the reaction is completed, allowing it to cool naturally to room temperature, washing the obtained product with ethanol and deionized water respectively, and drying the product in a 60°C drying oven to constant weight to obtain a semi-finished product material", the specific process of washing the obtained product with ethanol and deionized water is: first use 100 mL of ethanol to disperse the product, stir and wash it 3 times, filter it, and then use 100 mL of deionized water to stir and wash it 3 times to remove the ethanol on the surface of the product, and filter it to obtain a solid product.

6. A biochar catalyst, characterized in that: The biochar catalyst is prepared by the method for preparing the biochar catalyst based on waste cotton fabric as described in claim 5.

7. The biochar catalyst according to claim 6, characterized in that Water treatment methods applied to pollutants, specifically: To 100 mL of a solution containing pollutants, 2-10 mg of the biochar catalyst is added, and the concentration of persulfate is 0.05-0.5 mol / L to achieve efficient removal of pollutants, wherein the concentration of the pollutants is 0.5-10 mg / L, the water temperature is 15-30°C, and the initial pH of the solution is 3-11.

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