Biochar material for recycling rare and precious metals from waste solar cells and preparation method of biochar material

Abstract

The invention discloses a biochar material for recycling rare and precious metals from waste solar cells and a preparation method of the biochar material, and relates to the technical field of biochar materials. When the biochar material for recycling the rare and precious metals from the waste solar cells is prepared, firstly, biomass raw materials are dried, smashed, carbonized and carboxylated, and then biochar is prepared; growing a metal organic framework on the surface of the biochar in situ to prepare metal organic framework modified biochar; enabling the metal organic framework modified biochar to react with paraformaldehyde and diethyl phosphite to prepare phosphating modified biochar; reacting the phosphatized modified biochar with 3-bromopropylene to obtain modified biochar; and coating the surface of the modified biochar with an ion imprinting layer to prepare the biochar material for recycling rare and noble metals from waste solar cells. The biochar material for recycling rare and precious metals from waste solar cells prepared by the invention has the advantages of selective ion adsorption, high adsorption capacity and recyclability.

Description

Technical Field

[0001] This invention relates to the field of biochar materials technology, specifically to biochar materials for recycling rare and precious metals from waste solar cells and their preparation methods. Background Technology

[0002] With the widespread application of thin-film solar cells, the issue of recycling and reusing spent thin-film solar cells has become increasingly prominent. These cells contain various rare and precious metals, such as copper, indium, gallium, and selenium. Recycling these metals not only contributes to resource recycling but also reduces battery manufacturing costs, which is of great significance to environmental protection and sustainable development. However, due to the complex structure and material composition of thin-film solar cells, traditional recycling methods often struggle to achieve efficient enrichment and separation of rare and precious metals.

[0003] Although the total amount of rare and precious metals such as indium and gallium in the waste of thin-film solar cells is huge, their relative content is very low. Traditional extraction methods are inefficient, and although adsorption methods can be highly efficient in enriching, their selectivity is poor. They often contain a large number of metal atoms such as copper, zinc, and aluminum, and complex separation steps are required after enrichment. At the same time, due to the competitive adsorption of copper, zinc, and aluminum atoms, the recovery rate of metals such as indium and gallium is low, making it difficult to effectively enrich and recycle them. Therefore, in order to effectively enrich and recycle rare and precious metals in waste solar cells, it is urgent to develop a new material for the recycling of rare and precious metals in waste solar cells. Summary of the Invention

[0004] The purpose of this invention is to provide biochar materials for recycling rare and precious metals from waste solar cells and their preparation method, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A biochar material for recycling rare and precious metals from waste solar cells is prepared by coating an ion-imprinted layer on the surface of modified biochar. The modified biochar is prepared by reacting phosphate-modified biochar with 3-bromopropylene. The phosphating-modified biochar is prepared by reacting metal-organic framework modified biochar with paraformaldehyde and diethyl phosphite. The metal-organic framework modified biochar is prepared by in-situ growth of metal-organic frameworks on the surface of biochar. The biochar is prepared by drying and pulverizing biomass raw materials, followed by carbonization and carboxylation.

[0006] As an optimization, the metal-organic framework contains amino groups.

[0007] As an optimization, the ion-imprinted layer can simultaneously recognize indium and gallium ions.

[0008] As an optimization, the ion-imprinted layer also uses phosphate-containing monomers as functional monomers.

[0009] As an optimization, the biomass raw materials include banana peels, tea leaves, Chinese medicine residues, sludge, and aquatic plants.

[0010] A method for preparing biochar material for recycling rare and precious metals from waste solar cells includes the following preparation steps: (1) After washing the biomass raw material with pure water, dry it at 70~90℃ for 40~50h, crush it and pass it through a 100-mesh sieve. In a tube furnace under a nitrogen atmosphere, heat it to 450~550℃ for 3~4h at a heating rate of 4~5℃ / min. After cooling naturally to room temperature, grind it and pass it through a 400-mesh sieve. Add it to a 5mol / L nitric acid solution at a bath ratio of 1:(10~15)g / ml. Disperse it ultrasonically for 10~12min. Stir and reflux it at 85~95℃ and 300~400r / min for 4~5h to carboxylate it. Centrifuge to remove the liquid, wash it with pure water until neutral, and vacuum dry it at 80~90℃ for 10~12h to obtain biochar. (2) By mass fraction, 0.1-0.12 parts of biochar were added to 50-60 parts of dimethylformamide and ultrasonically dispersed for 20-30 min. Then, 0.05-0.06 parts of zirconium tetrachloride and 0.06-0.075 parts of 2-aminoterephthalic acid were added and mixed evenly. The mixture was then reacted in a hydrothermal reactor at 110-120℃ for 24-28 h. After cooling naturally to room temperature, the mixture was washed alternately by centrifugation with dimethylformamide and anhydrous ethanol. The mixture was then dispersed in 40-50 parts of anhydrous ethanol and reacted in a reactor at 95-105℃ for 10-12 h. After cooling naturally to room temperature, the mixture was washed alternately by centrifugation with dimethylformamide and anhydrous ethanol to remove the liquid. The precipitate was then vacuum dried at 80-90℃ for 10-12 h to obtain metal-organic framework modified biochar. (3) By mass fraction, 1.4-1.8 parts of metal-organic framework modified biochar, 0.08-0.1 parts of paraformaldehyde, 0.4-0.5 parts of diethyl phosphite, 0.1-0.12 parts of p-toluenesulfonic acid, and 90-120 parts of toluene are mixed evenly and stirred and refluxed at 90-100℃ and 200-300r / min for 10-12h. After cooling, the mixture is centrifuged to remove the liquid. The mixture is washed with pure water and anhydrous ethanol by alternating centrifugation to remove the liquid. The precipitate is dried under vacuum at 80-90℃ for 10-12h to obtain phosphating modified biochar. (4) Mix 2-3 parts of phosphate-modified biochar, 0.5-0.7 parts of potassium carbonate and 40-50 parts of acetonitrile by mass, sonicate at room temperature for 12-20 min, add 20-28 parts of 2wt% 3-bromopropene acetonitrile solution at 200-300 r / min at 55-65℃ under nitrogen atmosphere, at 0.8-1.2 ml / min, and after the addition is complete, stir and reflux for 10-12 h at 200-300 r / min at 55-65℃ under nitrogen atmosphere, filter, wash 2-3 times with pure water, petroleum ether and anhydrous ethanol respectively, and vacuum dry at 50-60℃ for 10-12 h to obtain modified biochar; (5) By mass, mix 1-1.2 parts of modified biochar and 500-600 parts of methanol, and ultrasonically disperse at room temperature for 10-15 min. Add 0.009-0.011 parts of gallium chloride, 0.013-0.017 parts of indium sulfate, 5-6 parts of dimethylformamide, 0.036-0.045 parts of allyl phosphate diethyl ester, and 0.018-0.022 parts of methacrylic acid, mix evenly, ultrasonically for 10-15 min at room temperature, and then stir at 200-300 r / min for 8-10 h. Add 0.4-0.5 parts of crosslinking agent and 0.01-0.012 parts of initiator and mix well. Under a nitrogen atmosphere, stir and reflux at 60-70℃ and 200-300 r / min for 22-24 h. Centrifuge to remove liquid, wash 2-3 times with methanol-water solution (volume ratio 1:4), wash with 0.5 mol / L hydrochloric acid solution until no metal ions are found, wash with pure water until neutral, and vacuum dry at 50-60℃ for 10-12 h to obtain biochar material for recycling rare and precious metals from waste solar cells.

[0011] As an optimization, the crosslinking agent in step (5) is one or more of N,N'-methylenebisacrylamide and ethylene glycol dimethacrylate.

[0012] As an optimization, the initiator in step (5) is one or more of azobisisobutyronitrile and ammonium persulfate.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are: In preparing biochar material for recycling rare and precious metals from waste solar cells, this invention first dries and pulverizes biomass raw materials, then carbonizes and carboxylates them to obtain biochar; a metal-organic framework is grown in situ on the surface of the biochar to obtain metal-organic framework modified biochar; the metal-organic framework modified biochar is reacted with paraformaldehyde and diethyl phosphite to obtain phosphating modified biochar; the phosphating modified biochar is reacted with 3-bromopropylene to obtain modified biochar; and an ion-imprinted layer is coated on the surface of the modified biochar to obtain biochar material for recycling rare and precious metals from waste solar cells.

[0014] First, carbonizing biomass raw materials at a suitable temperature can effectively preserve their original porous structure and naturally possess a high specific surface area. This can effectively increase the adsorption and modification sites for metals. Furthermore, by controlling the carbonization temperature, oxygen-containing functional groups can be retained while effectively carbonizing. These oxygen-containing functional groups leave a large number of reaction sites for subsequent modification, effectively improving the modification effect. Moreover, under the action of nitric acid, the carboxyl content on the surface of biochar is further increased, providing more active sites for the subsequent in-situ growth of metal-organic frameworks. Subsequently, metal-organic frameworks (MOFs) were grown in situ on the surface of biochar to prepare MOF-modified biochar. The surface of the carbonized and carboxylated biochar contained a large number of oxygen-containing functional groups such as carboxyl groups, and the high specific surface area also provided ample growth space for the MOFs. During the growth of the MOFs, zirconium ions were first adsorbed on the carboxyl groups and oxygen-containing functional groups on the surface of biochar, and then reacted with 2-aminoterephthalic acid to grow into MOFs with amino functional groups. The MOFs grown on biochar provided more adsorption sites for biochar, thereby effectively improving the adsorption capacity for metal ions. In addition, the amino groups not only improved the adsorption capacity for metal ions, but also provided reactive sites for subsequent modification.

[0015] Secondly, phosphating-modified biochar was prepared by reacting metal-organic framework-modified biochar with paraformaldehyde and diethyl phosphite. Phosphonate fragments were grafted onto the amino groups on the surface of the metal-organic framework-modified biochar via the Mannich reaction. Short-chain phosphonates have excellent adsorption and complexation capabilities for indium ions, which can effectively improve the selective adsorption and adsorption capacity for indium ions. Subsequently, 3-bromopropene was also grafted onto the amino functional groups. The grafting of 3-bromopropene introduced reactive double bonds to its surface, thus leaving reaction sites for subsequent preparation of ion-imprinted layers.

[0016] Finally, a biochar material for recycling rare and precious metals from waste solar cells was prepared by coating an ion-imprinted layer on the surface of modified biochar. Indium and gallium ions were used as metal ion templates, and an ion-imprinted layer with multi-ion recognition capability was coated on the surface of the modified biochar using ion imprinting technology. Ion imprinting technology has excellent specific recognition ability for metal ions. Therefore, coating the surface of the biochar material with an ion-imprinted layer can give it high selectivity for the required ions, acting as a gateway to allow most of the qualified metal ions to enter the interior for adsorption and fixation. At the same time, since there are many types of rare and precious metals in waste solar cells, the cost of using traditional ion imprinting materials to identify one ion at a time is high. Therefore, two rare and precious metal ions are identified at the same time for adsorption and enrichment. Since there are only two types of metal ions, the subsequent separation steps are simple, which can effectively improve the enrichment and recovery efficiency of rare and precious metals. Therefore, this invention uses an ion-imprinted layer with bimetallic recognition capability as the outer shell to improve the selectivity for rare and precious metal ions. Internally, it uses the modification of the metal-organic framework, the control of the carbonization process conditions, and the grafting of phosphonate fragments as means to improve the adsorption capacity. The two work together to effectively enrich and separate rare and precious metal ions with relatively low content for recovery. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] The raw material information used in all the following embodiments and comparative examples is as follows: Biomass raw material: tea residue, purchased from Huamo (Shandong) Biotechnology Co., Ltd.; Crosslinking agent: ethylene glycol dimethacrylate; Initiator: Azobisisobutyronitrile (AIBN).

[0019] Example 1: A method for preparing biochar material for recycling rare and precious metals from waste solar cells, the method comprising the following preparation steps: (1) After washing the biomass raw material with pure water, dry it at 70℃ for 50h, crush it and pass it through a 100-mesh sieve. In a tube furnace under a nitrogen atmosphere, heat it to 500℃ for 3h at a heating rate of 4℃ / min. After cooling naturally to room temperature, grind it and pass it through a 400-mesh sieve. Add it to a 5mol / L nitric acid solution at a bath ratio of 1:10g / ml. Disperse it ultrasonically for 10min. Stir and reflux it at 85℃ and 300r / min for 5h to carboxylate it. Centrifuge to remove the liquid, wash it with pure water until neutral, and vacuum dry it at 80℃ for 12h to obtain biochar. (2) By mass fraction, 0.1 parts of biochar were added to 50 parts of dimethylformamide and ultrasonically dispersed for 20 min. Then, 0.05 parts of zirconium tetrachloride and 0.06 parts of 2-aminoterephthalic acid were added and mixed evenly. The mixture was then reacted at 110°C for 28 h in a hydrothermal reactor. After cooling naturally to room temperature, the mixture was washed alternately by centrifugation with dimethylformamide and anhydrous ethanol. The mixture was then dispersed in 40 parts of anhydrous ethanol and reacted at 95°C for 12 h in a reaction vessel. After cooling naturally to room temperature, the mixture was washed alternately by centrifugation with dimethylformamide and anhydrous ethanol to remove the liquid. The precipitate was then vacuum dried at 80°C for 12 h to obtain metal-organic framework modified biochar. (3) By mass fraction, 1.4 parts of metal-organic framework modified biochar, 0.08 parts of paraformaldehyde, 0.4 parts of diethyl phosphite, 0.1 parts of p-toluenesulfonic acid and 90 parts of toluene were mixed evenly and stirred and refluxed at 90°C and 200 r / min for 12 h. After cooling, the mixture was centrifuged to remove the liquid. The mixture was washed with pure water and anhydrous ethanol by alternating centrifugation to remove the liquid. The precipitate was dried under vacuum at 80°C for 12 h to obtain phosphating modified biochar. (4) By mass, 2 parts of phosphate-modified biochar, 0.5 parts of potassium carbonate and 40 parts of acetonitrile are mixed evenly and sonicated at room temperature for 12 min. Under a nitrogen atmosphere, at 55°C and 200 r / min, 20 parts of 2wt% 3-bromopropene acetonitrile solution are added dropwise at 0.8 ml / min. After the addition is completed, under a nitrogen atmosphere, at 55°C and 200 r / min, the mixture is stirred and refluxed for 12 h. The mixture is filtered, washed twice with pure water, petroleum ether and anhydrous ethanol, respectively, and dried under vacuum at 50°C for 12 h to obtain modified biochar. (5) By mass, 1 part of modified biochar and 500 parts of methanol were mixed and ultrasonically dispersed at room temperature for 10 min. 0.009 parts of gallium chloride, 0.013 parts of indium sulfate, 5 parts of dimethylformamide, 0.036 parts of allyl phosphate diethyl ester and 0.018 parts of methacrylic acid were added and mixed evenly. The mixture was ultrasonically dispersed at room temperature for 10 min and then stirred at 200 r / min for 10 h. 0.4 parts of crosslinking agent and 0.01 parts of initiator were added and mixed evenly. The mixture was stirred and refluxed at 60 °C and 200 r / min for 24 h under a nitrogen atmosphere. The liquid was removed by centrifugation and washed twice with a methanol aqueous solution with a volume ratio of 1:4. The mixture was washed with 0.5 mol / L hydrochloric acid solution until no metal ions were found and then washed with pure water until neutral. The mixture was vacuum dried at 50 °C for 12 h to obtain biochar material for recycling rare and precious metals from waste solar cells.

[0020] Example 2: A method for preparing biochar material for recycling rare and precious metals from waste solar cells, the method comprising the following preparation steps: (1) After washing the biomass raw material with pure water, it was dried at 80℃ for 45h, pulverized and passed through a 100-mesh sieve. In a tube furnace under a nitrogen atmosphere, the temperature was raised to 500℃ for 3.5h at a heating rate of 4.5℃ / min. After naturally cooling to room temperature, it was ground and passed through a 400-mesh sieve. It was added to a 5mol / L nitric acid solution at a bath ratio of 1:12g / ml, ultrasonically dispersed for 11min, and carboxylated by stirring and reflux at 90℃ and 350r / min for 4.5h. After centrifugation to remove the liquid, it was washed with pure water until neutral and vacuum dried at 85℃ for 11h to obtain biochar. (2) By mass, 0.11 parts of biochar were added to 55 parts of dimethylformamide and ultrasonically dispersed for 25 min. Then, 0.055 parts of zirconium tetrachloride and 0.068 parts of 2-aminoterephthalic acid were added and mixed evenly. The mixture was then reacted at 115°C for 26 h in a hydrothermal reactor. After cooling naturally to room temperature, the mixture was washed alternately by centrifugation with dimethylformamide and anhydrous ethanol. The mixture was then dispersed in 45 parts of anhydrous ethanol and reacted at 100°C for 11 h in a reactor. After cooling naturally to room temperature, the mixture was washed alternately by centrifugation with dimethylformamide and anhydrous ethanol to remove the liquid. The precipitate was then vacuum dried at 85°C for 11 h to obtain metal-organic framework modified biochar. (3) By mass fraction, 1.6 parts of metal-organic framework modified biochar, 0.09 parts of paraformaldehyde, 0.45 parts of diethyl phosphite, 0.11 parts of p-toluenesulfonic acid and 105 parts of toluene were mixed evenly and stirred and refluxed at 95°C and 250 r / min for 11 h. After cooling, the mixture was centrifuged to remove the liquid. The mixture was washed with pure water and anhydrous ethanol by alternating centrifugation to remove the liquid. The precipitate was dried under vacuum at 85°C for 11 h to obtain phosphating modified biochar. (4) By mass, 2.5 parts of phosphate-modified biochar, 0.6 parts of potassium carbonate and 45 parts of acetonitrile were mixed evenly and sonicated at room temperature for 16 min. Under a nitrogen atmosphere, at 60°C and 250 r / min, 24 parts of 2wt% 3-bromopropene acetonitrile solution were added dropwise at 1 ml / min. After the addition was completed, the mixture was stirred and refluxed at 60°C and 250 r / min under a nitrogen atmosphere for 11 h. The mixture was filtered, washed twice with pure water, petroleum ether and anhydrous ethanol, respectively, and dried under vacuum at 55°C for 11 h to obtain modified biochar. (5) By mass, 1.1 parts of modified biochar and 550 parts of methanol were mixed and ultrasonically dispersed at room temperature for 12 min. 0.01 parts of gallium chloride, 0.014 parts of indium sulfate, 5.5 parts of dimethylformamide, 0.04 parts of allyl phosphate diethyl ester, and 0.02 parts of methacrylic acid were added and mixed evenly. The mixture was ultrasonically dispersed at room temperature for 12 min and then stirred at 250 r / min for 9 h. 0.45 parts of crosslinking agent and 0.011 parts of initiator were added and mixed evenly. The mixture was stirred and refluxed at 65 °C and 250 r / min for 23 h under a nitrogen atmosphere. The liquid was removed by centrifugation. The mixture was washed twice by centrifugation with a methanol aqueous solution with a volume ratio of 1:4. The mixture was washed with 0.5 mol / L hydrochloric acid solution until no metal ions were found. The mixture was then washed with pure water until neutral and vacuum dried at 55 °C for 11 h to obtain biochar material for recycling rare and precious metals from waste solar cells.

[0021] Example 3: A method for preparing biochar material for recycling rare and precious metals from waste solar cells, the method comprising the following preparation steps: (1) After washing the biomass raw material with pure water, dry it at 90℃ for 40h, crush it and pass it through a 100-mesh sieve. In a tube furnace under a nitrogen atmosphere, heat it to 500℃ for 4h at a heating rate of 5℃ / min. After cooling naturally to room temperature, grind it and pass it through a 400-mesh sieve. Add it to a 5mol / L nitric acid solution at a bath ratio of 1:15g / ml. Disperse it ultrasonically for 12min. Stir and reflux it at 95℃ and 400r / min for 4h to carboxylate it. Centrifuge to remove the liquid, wash it with pure water until neutral, and vacuum dry it at 90℃ for 10h to obtain biochar. (2) By mass fraction, 0.12 parts of biochar were added to 60 parts of dimethylformamide and ultrasonically dispersed for 30 min. Then, 0.06 parts of zirconium tetrachloride and 0.075 parts of 2-aminoterephthalic acid were added and mixed evenly. The mixture was then reacted at 120°C for 24 h in a hydrothermal reactor. After cooling naturally to room temperature, the mixture was washed alternately by centrifugation with dimethylformamide and anhydrous ethanol. The mixture was then dispersed in 50 parts of anhydrous ethanol and reacted at 105°C for 10 h in a reaction vessel. After cooling naturally to room temperature, the mixture was washed alternately by centrifugation with dimethylformamide and anhydrous ethanol to remove the liquid. The precipitate was then vacuum dried at 90°C for 10 h to obtain metal-organic framework modified biochar. (3) By mass, 1.8 parts of metal-organic framework modified biochar, 0.1 parts of paraformaldehyde, 0.5 parts of diethyl phosphite, 0.12 parts of p-toluenesulfonic acid and 120 parts of toluene were mixed evenly and stirred and refluxed at 100℃ and 300r / min for 10h. After cooling, the mixture was centrifuged to remove the liquid. The mixture was washed with pure water and anhydrous ethanol by alternating centrifugation to remove the liquid. The precipitate was dried under vacuum at 90℃ for 10h to obtain phosphating modified biochar. (4) By mass, 3 parts of phosphate-modified biochar, 0.7 parts of potassium carbonate and 50 parts of acetonitrile were mixed evenly and sonicated at room temperature for 20 min. Under a nitrogen atmosphere, at 65°C and 300 r / min, 28 parts of 2wt% 3-bromopropene acetonitrile solution were added dropwise at 1.2 ml / min. After the addition was completed, the mixture was stirred and refluxed at 65°C and 300 r / min under a nitrogen atmosphere for 10 h. The mixture was filtered, washed three times with pure water, petroleum ether and anhydrous ethanol respectively, and dried under vacuum at 60°C for 10 h to obtain modified biochar. (5) By mass, 1.2 parts of modified biochar and 600 parts of methanol were mixed and ultrasonically dispersed at room temperature for 15 min. 0.011 parts of gallium chloride, 0.017 parts of indium sulfate, 6 parts of dimethylformamide, 0.045 parts of allyl phosphate diethyl ester, and 0.022 parts of methacrylic acid were added and mixed evenly. The mixture was ultrasonically dispersed at room temperature for 15 min and then stirred at 300 r / min for 8 h. 0.5 parts of crosslinking agent and 0.012 parts of initiator were added and mixed evenly. The mixture was stirred and refluxed at 70 °C and 300 r / min for 22 h under a nitrogen atmosphere. The liquid was removed by centrifugation. The mixture was washed three times by centrifugation with a methanol aqueous solution with a volume ratio of 1:4. The mixture was washed with 0.5 mol / L hydrochloric acid solution until no metal ions were found. The mixture was then washed with pure water until neutral and vacuum dried at 60 °C for 10 h to obtain biochar material for recycling rare and precious metals from waste solar cells.

[0022] Example 4: The difference between the preparation method of biochar material for recycling rare and precious metals from waste solar cells in Example 4 and Example 2 is that the carbonization temperature in step (1) is 450℃. The remaining steps are the same as in Example 2.

[0023] Example 5: The difference between the preparation method of biochar material for recycling rare and precious metals from waste solar cells in Example 5 and Example 2 is that the carbonization temperature in step (1) is 550℃. The remaining steps are the same as in Example 2.

[0024] Comparative Example 1: The difference between the preparation method of biochar material for recycling rare and precious metals from waste solar cells in Comparative Example 1 and Example 2 is that the carbonization temperature in step (1) is 650℃. The remaining steps are the same as in Example 2.

[0025] Comparative Example 2: The difference between the preparation method of biochar material for recycling rare and precious metals from waste solar cells in Comparative Example 2 and Example 2 is that the carbonization temperature in step (1) is 750℃. The remaining steps are the same as in Example 2.

[0026] Comparative Example 3: The difference between the preparation method of biochar material for recycling rare and precious metals from waste solar cells in Comparative Example 3 and Example 2 lies in step (2). Step (2) is modified as follows: 0.11 parts by mass of biochar are added to 55 parts by dimethylformamide, ultrasonically dispersed for 25 min, 0.068 parts by mass of 2-aminoterephthalic acid are added, and after mixing evenly, the mixture is reacted in a hydrothermal reactor at 115°C for 26 h. After naturally cooling to room temperature, the mixture is washed alternately by centrifugation with dimethylformamide and anhydrous ethanol, dispersed in 45 parts by anhydrous ethanol, reacted in a reactor at 100°C for 11 h, and then naturally cooled to room temperature. The mixture is washed alternately by centrifugation with dimethylformamide and anhydrous ethanol to remove the liquid, and the precipitate is vacuum dried at 85°C for 11 h to obtain metal-organic framework modified biochar. The remaining steps are the same as in Example 2.

[0027] Comparative Example 4: The preparation method of biochar material for recycling rare and precious metals from waste solar cells in Comparative Example 4 differs from that in Example 2 in that step (3) is omitted, and step (4) is modified as follows: 2.5 parts by mass of metal-organic framework modified biochar, 0.6 parts by mass of potassium carbonate, and 45 parts by mass of acetonitrile are mixed evenly and sonicated at room temperature for 16 min. Under a nitrogen atmosphere, at 60°C and 250 r / min, 24 parts by mass of 2 wt% acetonitrile solution of 3-bromopropene are added dropwise at 1 ml / min. After the addition is complete, the mixture is stirred and refluxed at 60°C and 250 r / min under a nitrogen atmosphere for 11 h. The mixture is then filtered, washed twice with pure water, petroleum ether, and anhydrous ethanol, respectively, and dried under vacuum at 55°C for 11 h to obtain modified biochar. The remaining steps are the same as in Example 2.

[0028] Comparative Example 5: The preparation method of biochar material for recycling rare and precious metals from waste solar cells in Comparative Example 5 differs from that in Example 2 in that step (4) is omitted, and step (5) is modified as follows: 1.1 parts by mass of phosphate-modified biochar and 550 parts by mass of methanol are mixed and ultrasonically dispersed at room temperature for 12 min. Then, 0.01 parts by mass of gallium chloride, 0.014 parts by mass of indium sulfate, 5.5 parts by mass of dimethylformamide, 0.04 parts by mass of diethyl allyl phosphate, and 0.02 parts by mass of methacrylic acid are added and mixed evenly. The mixture is then ultrasonically dispersed at room temperature for 1 minute. After stirring at 250 rpm for 9 hours, add 0.45 parts of crosslinking agent and 0.011 parts of initiator and mix thoroughly. Under a nitrogen atmosphere, reflux the mixture at 65°C and 250 rpm for 23 hours. Centrifuge to remove the liquid, wash twice with a methanol-water solution (volume ratio 1:4), wash with 0.5 mol / L hydrochloric acid solution until no metal ions are found, and then wash with pure water until neutral. Dry under vacuum at 55°C for 11 hours to obtain biochar material for recycling rare and precious metals from waste solar cells. The remaining steps are the same as in Example 2.

[0029] Comparative Example 6: The difference between the preparation method of biochar material for recycling rare and precious metals from waste solar cells in Comparative Example 6 and Example 2 lies in the difference in step (5). Step (5) is modified as follows: 1.1 parts of modified biochar and 550 parts of methanol are mixed by mass, ultrasonically dispersed at room temperature for 12 min, 0.02 parts of gallium chloride, 5.5 parts of dimethylformamide, 0.04 parts of allyl phosphate diethyl ester and 0.02 parts of methacrylic acid are added and mixed evenly, ultrasonically for 12 min at room temperature, and then stirred at 250 r / min for 9 h. 0.45 parts of crosslinking agent and 0.011 parts of initiator are added and mixed evenly. The mixture is stirred and refluxed at 65°C and 250 r / min for 23 h under a nitrogen atmosphere. The liquid is removed by centrifugation, and the mixture is washed twice by centrifugation with a methanol aqueous solution with a volume ratio of 1:4. The mixture is washed with 0.5 mol / L hydrochloric acid solution until no metal ions are present, and then washed with pure water until neutral. The mixture is vacuum dried at 55°C for 11 h to obtain biochar material for recycling rare and precious metals from waste solar cells. The remaining steps are the same as in Example 2.

[0030] Comparative Example 7: The difference between the preparation method of biochar material for recycling rare and precious metals from waste solar cells in Comparative Example 7 and Example 2 lies in the difference in step (5). Step (5) is modified as follows: 1.1 parts of modified biochar and 550 parts of methanol are mixed by mass, ultrasonically dispersed at room temperature for 12 min, 0.028 parts of indium sulfate, 5.5 parts of dimethylformamide, 0.04 parts of allyl phosphate diethyl ester and 0.02 parts of methacrylic acid are added and mixed evenly, ultrasonically for 12 min at room temperature, and then stirred at 250 r / min for 9 h. 0.45 parts of crosslinking agent and 0.011 parts of initiator are added and mixed evenly. The mixture is stirred and refluxed at 65°C and 250 r / min for 23 h under a nitrogen atmosphere. The liquid is removed by centrifugation, and the mixture is washed twice by centrifugation with a methanol aqueous solution with a volume ratio of 1:4. The mixture is then washed with 0.5 mol / L hydrochloric acid solution until no metal ions are present, and then washed with pure water until neutral. The mixture is vacuum dried at 55°C for 11 h to obtain biochar material for recycling rare and precious metals from waste solar cells. The remaining steps are the same as in Example 2.

[0031] Comparative Example 8: The difference between the preparation method of biochar material for recycling rare and precious metals from waste solar cells in Comparative Example 8 and Example 2 lies in step (5). Step (5) is modified as follows: 1.1 parts by mass of modified biochar and 550 parts by mass of methanol are mixed and ultrasonically dispersed at room temperature for 12 min. Then, 0.01 parts by mass of gallium chloride, 0.014 parts by mass of indium sulfate, 5.5 parts by mass of dimethylformamide, and 0.04 parts by mass of methacrylic acid are added and mixed evenly. The mixture is ultrasonically dispersed at room temperature for 12 min, then stirred at 250 r / min for 9 h. Finally, 0.45 parts by mass of crosslinking agent and 0.011 parts by mass of initiator are added and mixed evenly. The mixture is then refluxed at 65°C and 250 r / min under a nitrogen atmosphere for 23 h. The liquid is removed by centrifugation, and the mixture is washed twice with a methanol aqueous solution at a volume ratio of 1:4. The mixture is then washed with 0.5 mol / L hydrochloric acid solution until no metal ions are present, and then washed with pure water until neutral. The mixture is then vacuum dried at 55°C for 11 h to obtain the biochar material for recycling rare and precious metals from waste solar cells. The remaining steps are the same as in Example 2.

[0032] Comparative Example 9: The preparation method of biochar material for recycling rare and precious metals from waste solar cells in Comparative Example 9 differs from that in Example 2 in step (5). Step (5) is modified as follows: 1.1 parts by mass of modified biochar and 550 parts by mass of methanol are mixed and ultrasonically dispersed at room temperature for 12 min. Then, 5.5 parts by mass of dimethylformamide, 0.04 parts by mass of diethyl allyl phosphate, and 0.02 parts by mass of methacrylic acid are added and mixed evenly. The mixture is ultrasonically dispersed at room temperature for 12 min, then stirred at 250 r / min for 9 h. Finally, 0.45 parts by mass of crosslinking agent and 0.011 parts by mass of initiator are added and mixed evenly. The mixture is then refluxed at 65°C and 250 r / min under a nitrogen atmosphere for 23 h. The liquid is removed by centrifugation, and the mixture is washed twice with a methanol aqueous solution at a volume ratio of 1:4. The mixture is then washed with 0.5 mol / L hydrochloric acid solution until no metal ions are present, and then washed with pure water until neutral. The mixture is then vacuum dried at 55°C for 11 h to obtain the biochar material for recycling rare and precious metals from waste solar cells. The remaining steps are the same as in Example 2.

[0033] Test Example 1: Adsorption performance test of rare and precious metal ions: The adsorption capacity of the prepared biochar material for recycling rare and precious metals from waste solar cells for indium and gallium was tested, and the performance retention rate after multiple adsorption-desorption cycles was evaluated to assess its enrichment effect and recycling performance of rare and precious metal ions. The specific test method is as follows: Adsorption capacity: 10 mg of the biochar material for recycling rare and precious metals from waste solar cells prepared in each example and comparative example was added to 40 ml of metal ion liquid. The pH of the metal ion liquid was 3, and it contained 100 mg / L of Ga. 3+ In 3 + Ions were adsorbed at room temperature on a shaker at 200 rpm for 12 h. The concentrations of each metal ion in the solution before and after adsorption were accurately measured by inductively coupled plasma mass spectrometry, and the adsorption capacity Q was calculated. The adsorption capacity Q was calculated for Ga. 3+ In 3+ The adsorption capacity of ions is calculated using the formula: Q = (C0 - C) / (C) e )×V÷m; where Q is the adsorption capacity in mg / g, C0 is the initial concentration in mg / L, and C e The concentration after adsorption is in mg / L, V is the solution volume in L, and m is the mass of biochar material for recycling rare and precious metals from waste solar cells in g; each group was tested in parallel 5 times, and the average value was recorded. Recycling performance: Referring to the test method of adsorption capacity, the biochar material for recycling rare and precious metals from waste solar cells after adsorption was desorbed with 0.5 mol / L hydrochloric acid solution until no corresponding metal ions were found. One cycle consists of one adsorption and one desorption. After 10 cycles, the adsorption capacity retention rate is calculated by comparing the remaining adsorption capacity in the last cycle with the initial adsorption capacity. Each group was tested in parallel 5 times, and the average value was recorded.

[0034] The results are shown in Table 1.

[0035] Table 1 A comparison of the experimental data from Examples 1-5 and Comparative Examples 1-9 in Table 1 reveals that the biochar material for recycling rare and precious metals from waste solar cells prepared in this invention has good adsorption capacity and recycling performance.

[0036] By comparing the data in the table, the data from Examples 4 and 5 show that the performance will not change drastically when the carbonization temperature is reasonably changed.

[0037] By comparing the data in the table, the data in Comparative Examples 1 and 2 show that excessively high carbonization temperatures result in fewer biochar binding sites and a lower content of remaining oxygen-containing groups, leading to a decrease in adsorption performance.

[0038] The data comparison in the table shows that the growth of metal-organic frameworks, the grafting of phosphonate fragments, and the grafting of 3-bromopropene can all improve the adsorption performance and enhance the adsorption performance for gallium and indium ions.

[0039] The data comparison in the table (compare figures 6-9) demonstrates that the preparation of the ion-imprinted layer effectively improves the adsorption performance of gallium and indium ions.

[0040] Test Example 2: Selective adsorption performance test: The selective adsorption performance of the prepared biochar material for recycling rare and precious metals from waste solar cells is evaluated by testing the selective adsorption coefficient of the target ions under heteroatom interference. The specific test method is as follows: Selection of adsorption performance: Refer to adsorption capacity test, except that the metal ion liquid used contains 10 mg / L Ga. 3+ Ions, 10 mg / L In 3+ Ions, 200 mg / L Cu 2+ Ions, 200 mg / L Zn 2+ Ions, 200 mg / L Al 3+ For each ion, the adsorption capacity was tested, and the selectivity factor K was calculated according to the following formula. Ga / m With K In / m Where m represents Cu 2+ Zn2+ Al 3+ ; K d =Q÷C e ;K Ga / m =K d (Ga)÷K d (m); K In / m =K d (In)÷K d (m); In the formula, K d Let Q be the equilibrium distribution coefficient, Q be the adsorption capacity, and C be the equilibrium distribution coefficient. e This represents the concentration of metal ions after adsorption. The results are shown in Table 2.

[0041] Table 2 A comparison of the experimental data from Examples 1-5 and Comparative Examples 1-9 in Table 2 reveals that the biochar material for recycling rare and precious metals from waste solar cells prepared in this invention exhibits excellent selective adsorption properties.

[0042] By comparing the data in the table, the data in Comparative Examples 1 and 2 show that excessively high carbonization temperatures result in low oxygen-containing group content, fewer reaction grafting sites, and poor modification effects.

[0043] By comparing the data in the table, the data in Comparative Examples 6 to 9 show that the preparation of the ion-imprinted layer effectively improves the selective adsorption performance of gallium and indium ions.

[0044] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A biochar material for recycling rare and precious metals from waste solar cells, characterized in that, The biochar material for recycling rare and precious metals from waste solar cells is prepared by coating an ion-imprinted layer on the surface of modified biochar. The modified biochar is prepared by reacting phosphate-modified biochar with 3-bromopropylene. The phosphating-modified biochar is prepared by reacting metal-organic framework modified biochar with paraformaldehyde and diethyl phosphite. The metal-organic framework modified biochar is prepared by in-situ growth of metal-organic frameworks on the surface of biochar. The biochar is prepared by drying and pulverizing biomass raw materials, followed by carbonization and carboxylation. The metal-organic framework contains amino groups.

2. The biochar material for recycling rare and precious metals from waste solar cells according to claim 1, characterized in that, The ion-imprinted layer can simultaneously identify indium and gallium ions; The ion-imprinted layer also uses phosphate ester monomers as functional monomers.

3. The biochar material for recycling rare and precious metals from waste solar cells according to claim 1, characterized in that, The biomass raw materials include banana peels, tea leaves, Chinese medicine residues, sludge, and aquatic plants.

4. A method for preparing biochar material for recycling rare and precious metals from waste solar cells according to claim 1, characterized in that, The preparation steps include the following: (1) Wash the biomass raw material, dry it, crush and sieve it, carbonize it in a tube furnace, cool it, grind and sieve it, add it to nitric acid solution, ultrasonically disperse it, stir and reflux it for carboxylation, centrifuge it, wash it, dry it, and obtain biochar. (2) Add biochar to dimethylformamide, ultrasonically disperse, add zirconium tetrachloride and 2-aminoterephthalic acid and mix evenly, react in a hydrothermal reactor, cool, wash, disperse in anhydrous ethanol, react in a reaction vessel, cool, wash, dry, and obtain metal-organic framework modified biochar. (3) Mix metal-organic framework modified biochar, paraformaldehyde, diethyl phosphite, p-toluenesulfonic acid and toluene evenly, stir and reflux to react, cool and centrifuge, remove liquid, wash and dry to obtain phosphating modified biochar. (4) Mix the phosphate-modified biochar, potassium carbonate and acetonitrile evenly, sonicate at room temperature, add acetonitrile solution of 3-bromopropene dropwise under nitrogen atmosphere, stir and reflux reaction under nitrogen atmosphere, filter, wash and dry to obtain modified biochar. (5) Mix modified biochar and methanol, disperse ultrasonically at room temperature, add gallium chloride, indium sulfate, dimethylformamide, diethyl allyl phosphate and methacrylic acid and mix evenly, sonicate at room temperature, stir, add crosslinking agent and initiator and mix evenly, stir and reflux reaction under nitrogen atmosphere, centrifuge to remove liquid, wash, dry, and obtain biochar material for recycling rare and precious metals from waste solar cells.

5. The method for preparing biochar material for recycling rare and precious metals from waste solar cells according to claim 4, characterized in that, The biochar in step (1) is prepared by washing the biomass raw material with pure water, drying it, crushing it and passing it through a 100-mesh sieve, carbonizing it in a tube furnace under a nitrogen atmosphere at a heating rate of 4-5℃ / min to 450-550℃ for 3-4 hours, naturally cooling it to room temperature, grinding it and passing it through a 400-mesh sieve, adding it to a 5mol / L nitric acid solution at a bath ratio of 1:(10-15)g / ml, ultrasonically dispersing it, stirring and refluxing it at 85-95℃ for 4-5 hours for carboxylation, centrifuging to remove the liquid, washing it until neutral, and vacuum drying it.

6. The method for preparing biochar material for recycling rare and precious metals from waste solar cells according to claim 4, characterized in that, The metal-organic framework modified biochar in step (2) is prepared by adding 0.1-0.12 parts of biochar to 50-60 parts of dimethylformamide by mass, ultrasonically dispersing, adding 0.05-0.06 parts of zirconium tetrachloride and 0.06-0.075 parts of 2-aminoterephthalic acid and mixing evenly, reacting in a hydrothermal reactor at 110-120℃ for 24-28h, naturally cooling to room temperature, washing, dispersing in 40-50 parts of anhydrous ethanol, reacting in a reactor at 95-105℃ for 10-12h, naturally cooling to room temperature, washing, and vacuum drying.

7. The method for preparing biochar material for recycling rare and precious metals from waste solar cells according to claim 4, characterized in that, The phosphating modified biochar in step (3) is prepared by mixing 1.4-1.8 parts of metal-organic framework modified biochar, 0.08-0.1 parts of paraformaldehyde, 0.4-0.5 parts of diethyl phosphite, 0.1-0.12 parts of p-toluenesulfonic acid, and 90-120 parts of toluene by mass, stirring and refluxing at 90-100℃ for 10-12 hours, cooling, centrifuging to remove liquid, washing, and vacuum drying.

8. The method for preparing biochar material for recycling rare and precious metals from waste solar cells according to claim 4, characterized in that, The modified biochar in step (4) is prepared by mixing 2-3 parts of phosphate-modified biochar, 0.5-0.7 parts of potassium carbonate, and 40-50 parts of acetonitrile by mass, ultrasonicating at room temperature for 12-20 min, and adding 20-28 parts of 2wt% 3-bromopropene acetonitrile solution dropwise at 55-65℃ under a nitrogen atmosphere at 0.8-1.2 ml / min. After the addition is complete, the mixture is stirred and refluxed at 55-65℃ under a nitrogen atmosphere for 10-12 h, filtered, washed, and vacuum dried.

9. The method for preparing biochar material for recycling rare and precious metals from waste solar cells according to claim 4, characterized in that, The biochar material for recycling rare and precious metals from waste solar cells described in step (5) is prepared by mixing 1-1.2 parts modified biochar and 500-600 parts methanol by mass, ultrasonically dispersing at room temperature for 10-15 min, adding 0.009-0.011 parts gallium chloride, 0.013-0.017 parts indium sulfate, 5-6 parts dimethylformamide, 0.036-0.045 parts diethyl allyl phosphate, and 0.018-0.022 parts methacrylic acid, mixing evenly, ultrasonicating at room temperature for 10-15 min, stirring for 8-10 h, adding 0.4-0.5 parts crosslinking agent and 0.01-0.012 parts initiator, mixing evenly, and stirring and refluxing at 60-70°C for 22-24 h under a nitrogen atmosphere. After centrifugation to remove the liquid, washing, washing with hydrochloric acid solution until no metal ions are present, washing again until neutral, and vacuum drying to obtain the final product.

10. The method for preparing biochar material for recycling rare and precious metals from waste solar cells according to claim 9, characterized in that, The crosslinking agent is one or more of N,N'-methylenebisacrylamide and ethylene glycol dimethacrylate; The initiator is one or more of azobisisobutyronitrile and ammonium persulfate.

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