Scrapped lithium battery solid waste recovery method, gypsum adsorbent and application

Abstract

The invention provides a scrapped lithium battery solid waste recovery method, which comprises: S1, providing calcium sulfate slag, graphite slag and waste activated carbon, and sequentially purifying and modifying the graphite slag to obtain graphene oxide; s2, adding water into the calcium sulfate residues to prepare slurry, adding a binder, heating until the binder is completely dissolved, and then adding the waste activated carbon and the graphene oxide to obtain an adsorbent precursor; and S3, performing high-temperature desorption on the adsorbent precursor in an inert atmosphere to obtain the gypsum adsorbent. According to the invention, solid wastes, namely calcium sulfate slag, graphite slag and waste activated carbon, generated in the recovery process of scrapped lithium batteries are treated as raw materials to prepare the composite efficient adsorption material, and the material has good adsorption and decoloration performance on dye wastewater.

Description

Technical Field

[0001] The present invention relates to the fields of scrap lithium battery recycling and water treatment, and in particular to a scrap lithium battery solid waste recycling method, a carbon-based modified gypsum adsorbent and applications. Background Art

[0002] In recent years, to achieve the dual carbon goals, China has increased its support for the new energy vehicle industry. As a result, the use of lithium-ion batteries has gradually increased, but their lifespan is generally only 5-8 years. This has led to a large number of lithium-ion batteries being scrapped. It is estimated that by 2030, the scrapped lithium-ion battery capacity will reach 100-120GW / h. Currently, the recycling of scrapped batteries is based on the recovery of metals such as lithium, nickel, cobalt, manganese, copper, and aluminum in the positive electrode materials. However, the negative electrode materials are basically treated as solid waste and rarely recycled. Furthermore, the calcium sulfate residue and waste activated carbon generated during the wastewater treatment process of used battery recycling also need to be treated as solid waste, increasing production costs for companies.

[0003] Dye wastewater has high chroma, contains a high number of organic pollutants, and has a complex and variable composition. It exhibits strong biotoxicity and is difficult to biodegrade. Current methods for treating industrial dye wastewater primarily include biological treatment, chemical flocculation, chemical oxidation, adsorption, and electrochemical methods. Two main types of adsorbents are used in the dye industry for wastewater treatment: Materials with large surface areas, such as silica polymers and macroporous resins, are effective in removing dye chroma, but their relatively high cost makes them difficult to promote. Lower-cost materials, such as kaolin and industrial slag, are also under investigation for their decolorization potential. Currently, the maximum adsorption capacity of kaolin for methylene blue is only 59.947 mg / g. Therefore, there is an urgent need to develop efficient, low-cost dye adsorbents. Summary of the Invention

[0004] The present invention aims to address at least one of the technical problems existing in the aforementioned prior art. To this end, the present invention proposes a method for recycling scrapped lithium battery solid waste, a carbon-based modified gypsum adsorbent, and its application. The present invention uses solid waste generated during the scrapped lithium battery recycling process—calcium sulfate slag, graphite slag, and waste activated carbon—as raw materials to produce a composite, high-efficiency adsorption material with excellent adsorption and decolorization properties for dye wastewater.

[0005] According to a first aspect of the present invention, a method for recycling scrapped lithium batteries comprises the following steps:

[0006] S1: providing calcium sulfate slag, graphite slag and waste activated carbon, and purifying and modifying the graphite slag in sequence to obtain graphene oxide;

[0007] S2: adding water to the calcium sulfate slag to prepare a slurry, adding a binder and heating until the binder is completely dissolved, and then adding the waste activated carbon and the graphene oxide to obtain an adsorbent precursor;

[0008] S3: performing high-temperature desorption on the adsorbent precursor under an inert atmosphere to obtain a gypsum adsorbent.

[0009] The calcium sulfate slag in the present invention is produced during the treatment of wastewater from the neutralization of lithium iron phosphate synthesis mother liquor from used batteries. It has a purity of 90% to 95% and is primarily composed of calcium sulfate dihydrate. Waste activated carbon can be obtained from an exhaust gas absorption tower and has adsorbed various organic pollutants. Graphite slag can be obtained by drying and pulverizing negative electrode graphite from wet-process recycling of used lithium iron phosphate or used ternary batteries. It contains iron phosphate as well as copper, aluminum, nickel, cobalt, and manganese compounds.

[0010] In some embodiments, step S1 further includes: making the calcium sulfate slag no coarser than 100 mesh, and making the waste activated carbon and the graphene oxide no coarser than 400 mesh.

[0011] In some embodiments, in step S1, the purification includes the following steps: sequentially performing acid washing and hot water washing on the graphite slag.

[0012] In some preferred embodiments, the pickling comprises the following steps: mixing the graphite slag with sulfuric acid having a concentration of 1.7 to 2.0 mol / L at a solid-liquid ratio of 1: (3 to 3.5) g / mL, stirring the mixture in a water bath at 70 to 75° C. for 4 to 5 hours, and then filtering the mixture.

[0013] In some preferred embodiments, the hot water washing comprises the following steps: washing the acid-washed graphite slag with 90° C. hot water under suction filtration, wherein the mass ratio of the hot water to the graphite slag is (5-6):1, and repeating 3-5 times.

[0014] Through the above purification process, more than 90% of iron phosphate, copper, aluminum, nickel, cobalt and manganese in the graphite slag can be removed. Therefore, the present invention can also directly use the graphite powder obtained by crushing the whole battery pack, which has a wider source of raw materials.

[0015] In some embodiments, in step S1, the modification includes the following steps: mixing the purified graphite slag with nitrate and acid, adding an oxidant for oxidation under ice bath conditions, adding water for reaction under water bath conditions, then adding a reducing agent at room temperature, performing solid-liquid separation after the reaction is completed, washing and drying the solid phase to obtain the graphene oxide.

[0016] In some preferred embodiments, the mass ratio of the graphite slag to the nitrate is 2: (1-3); and / or the oxidant is potassium permanganate, and the mass ratio of the graphite slag to the oxidant is 1: (2-5); and / or the mass ratio of the graphite slag to the water is 1: (30-50).

[0017] In some preferred embodiments, the reducing agent is selected from 30% by mass of hydrogen peroxide. The present invention removes unreacted potassium permanganate in the reaction solution by using the reducing agent, and the potassium permanganate is considered to be completely consumed when the reducing agent is added until the reaction solution no longer generates a large number of bubbles.

[0018] In some preferred embodiments, the nitrate is at least one of sodium nitrate or potassium nitrate.

[0019] In some preferred embodiments, the acid is selected from concentrated sulfuric acid with a mass fraction of 98%, and the mass ratio of the graphite slag to the concentrated sulfuric acid is 1:(20-22).

[0020] In some preferred embodiments, the temperature of the ice bath is 0-5° C., and the oxidation time is 2-2.5 h; and / or the temperature of the water bath is 90-95° C., and the reaction time is 0.5-1 h.

[0021] In some embodiments, the washing comprises the following steps: eluting the graphene oxide with hydrochloric acid having a mass fraction of 10% to 15% under suction filtration conditions, washing the solid phase with water to a pH of 6 to 7, and then drying at 105 to 110°C.

[0022] In some embodiments, in step S2, the binder is at least one of gelatin and polyethylene glycol; and / or the mass of the binder is 10% to 40% of the mass of the calcium sulfate slag. Without the addition of a binder, the calcium sulfate slag, graphene oxide, and waste activated carbon will still be severely separated after mixing, and the adsorption effect cannot be further improved by the individual materials.

[0023] In some embodiments, in step S2, the heating is performed by heating the temperature to 65-70° C. and then keeping the temperature for 1-1.5 hours.

[0024] In some embodiments, in step S2, the mass ratio of the calcium sulfate slag, the waste activated carbon, and the graphene oxide is 5:(1-3):(1-4).

[0025] In some embodiments, after adding the waste activated carbon and the graphene oxide in step S2, the process further includes stirring at 40-50° C. for 4-5 hours. During the stirring process, the graphene oxide and the waste activated carbon are fully cross-linked and loaded on the surface of the calcium sulfate slag matrix.

[0026] In some embodiments, in step S3, the inert atmosphere is a nitrogen atmosphere.

[0027] In some embodiments, in step S3, the high-temperature desorption is performed at a temperature of 550°C to 800°C for 2 to 4 hours. High-temperature desorption carbonizes the binder while removing the electrolyte and binder from the graphene oxide and organic matter adsorbed from the waste activated carbon, thereby increasing the porosity and active sites of the composite material.

[0028] According to a second aspect of the present invention, a gypsum adsorbent is provided, comprising a calcium sulfate matrix and graphene and activated carbon supported on the calcium sulfate matrix; the gypsum adsorbent has a porosity of 85% to 90%, a pore size distribution of 20 to 100 nm, and a specific surface area of 860 to 900 m 2 / g. Gypsum, waste activated carbon and graphite all have certain adsorption capacity. By processing and modifying them into composite adsorption materials, the adsorption performance can be further improved.

[0029] According to a third aspect of the present invention, a method according to the first aspect or a gypsum adsorbent according to the second aspect is used in the treatment of dye wastewater. The gypsum adsorbent prepared by the present invention exhibits excellent adsorption and decolorization properties for dye wastewater, achieving a methylene blue removal rate of 97.27% and an adsorption capacity of 410.74 mg / g.

[0030] According to one embodiment of the present invention, there are at least the following beneficial effects:

[0031] 1. The calcium sulfate slag, waste activated carbon, and graphite slag used in the present invention are all solid wastes generated in the process of recycling waste batteries. Through the process of the present invention, waste is turned into treasure, solid waste is utilized as a resource, and pollution to the environment by solid waste is avoided;

[0032] 2. After long-term lithium insertion and removal during charge and discharge, the graphite slag not only increases its specific surface area and pore structure, but also contains a large number of functional groups and dielectric pores on the surface. Compared with natural graphite, the graphene adsorption material prepared by oxidation of graphite slag has higher adsorption efficiency;

[0033] 3. The present invention uses calcium sulfate as a matrix, utilizes the electrostatic adsorption force and pore structure of its surface, and under the action of a binder, effectively loads carbon-based materials such as graphene oxide and waste activated carbon on the surface of calcium sulfate to obtain a composite adsorption material, which effectively improves its adsorption performance;

[0034] 4. The present invention performs high-temperature treatment on the composite material in a nitrogen atmosphere. At this temperature, on the one hand, the binder is carbonized and converted into a multi-porous, large-specific-surface carbon material. On the other hand, the organic matter embedded in and adsorbed in the activated carbon and graphene is decomposed or desorbed, and the adsorption performance of the composite material is further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0036] Figure 1 This is a SEM image of the carbon-based modified calcium sulfate composite material prepared in Example 13 of the present invention, magnified 10,000 times. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with the embodiments so as to fully understand the purpose, characteristics and effects of the present invention.

[0038] Unless otherwise specified, the raw materials, reagents, and apparatus used in the following examples can be obtained from conventional commercial sources or by known methods. Graphite slag is produced by wet recycling of waste lithium iron phosphate or ternary batteries; calcium sulfate slag is produced from the neutralization of wastewater from the mother liquor of iron phosphate synthesis from waste batteries, with a purity of 92%. Waste activated carbon is obtained from the exhaust gas absorption tower on the roof of the laboratory building of Yichang Bangpu Recycling Technology Co., Ltd.; and gelatin is purchased from Xilong Science Co., Ltd.

[0039] Example 1

[0040] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite, comprising the following steps:

[0041] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0042] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0043] 3. After the reaction is completed, filter the graphite slag with suction. After the filtration is completed, rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then use an oven to dry at 105°C for later use. The composition of the graphite slag before and after impurity removal is shown in Table 1:

[0044] Table 1 Composition data of graphite slag before and after impurity removal (dry basis)

[0045] Element C(％) Fe(%) P(％) Cu(%) Al(％) Ni(%) Co(%) Mn (%) As is 82.332 4.685 3.591 0.325 0.546 0.213 0.135 0.326 After removing impurities 93.683 0.316 0.232 0.034 0.047 0.031 0.017 0.029

[0046] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 2g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 4g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0047] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0048] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0049] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0050] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0051] 9. While stirring, add 1g of waste activated carbon and 1g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4h, and filter and dry after the reaction is complete.

[0052] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 550°C under nitrogen protection for 3 hours, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 1. The porosity of the gypsum adsorbent 1 was 89.2%, the pore size distribution was 20-100 nm, and the specific surface area was 876.3 m 2 / g, the above porosity, pore size distribution and specific surface area are all obtained by gas adsorption method.

[0053] Example 2

[0054] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite. The difference from Example 1 is that the amount of sodium nitrate used in step 4 is 1 g. The method comprises the following steps:

[0055] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0056] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0057] 3. After the reaction is completed, filter the graphite slag with suction. Rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then dry it in an oven at 105°C for later use.

[0058] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 1g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 4g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0059] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0060] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0061] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0062] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0063] 9. While stirring, add 1g of waste activated carbon and 1g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4h, and filter and dry after the reaction is complete.

[0064] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 550° C. under nitrogen protection for 3 h, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 2.

[0065] Example 3

[0066] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite. The difference from Example 1 is that the amount of sodium nitrate used in step 4 is 3 g. The method comprises the following steps:

[0067] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0068] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0069] 3. After the reaction is completed, filter the graphite slag with suction. Rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then dry it in an oven at 105°C for later use.

[0070] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 3g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 4g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0071] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0072] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0073] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0074] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0075] 9. While stirring, add 1g of waste activated carbon and 1g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4h, and filter and dry after the reaction is complete.

[0076] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 550° C. under nitrogen protection for 3 h, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 3.

[0077] Example 4

[0078] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite. The difference from Example 2 is that the amount of potassium permanganate used in step 4 is 6 g. The method comprises the following steps:

[0079] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0080] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0081] 3. After the reaction is completed, filter the graphite slag with suction. Rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then dry it in an oven at 105°C for later use.

[0082] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 1g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 6g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0083] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0084] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0085] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0086] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0087] 9. While stirring, add 1g of waste activated carbon and 1g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4h, and filter and dry after the reaction is complete.

[0088] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 550° C. under nitrogen protection for 3 h, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 4.

[0089] Example 5

[0090] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite. The difference from Example 2 is that the amount of potassium permanganate used in step 4 is 8 g. The method comprises the following steps:

[0091] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0092] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0093] 3. After the reaction is completed, filter the graphite slag with suction. Rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then dry it in an oven at 105°C for later use.

[0094] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 1g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 8g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0095] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0096] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0097] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0098] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0099] 9. While stirring, add 1g of waste activated carbon and 1g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4h, and filter and dry after the reaction is complete.

[0100] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 550° C. under nitrogen protection for 3 h, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 5.

[0101] Example 6

[0102] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite. The difference from Example 2 is that the amount of potassium permanganate used in step 4 is 10 g. The method comprises the following steps:

[0103] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0104] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0105] 3. After the reaction is completed, filter the graphite slag with suction. Rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then dry it in an oven at 105°C for later use.

[0106] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 1g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 10g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0107] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0108] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0109] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0110] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0111] 9. While stirring, add 1g of waste activated carbon and 1g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4h, and filter and dry after the reaction is complete.

[0112] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 550° C. under nitrogen protection for 3 h, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 6.

[0113] Example 7

[0114] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite. The difference from Example 5 is that the amount of waste activated carbon used in step 9 is 2 g. The method comprises the following steps:

[0115] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0116] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0117] 3. After the reaction is completed, filter the graphite slag with suction. Rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then dry it in an oven at 105°C for later use.

[0118] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 1g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 8g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0119] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0120] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0121] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0122] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0123] 9. Under stirring, add 2g of waste activated carbon and 1g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4h, and filter and dry after the reaction is complete.

[0124] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 550° C. under nitrogen protection for 3 h, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 7.

[0125] Example 8

[0126] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite. The difference from Example 5 is that the amount of waste activated carbon used in step 9 is 3 g. The method comprises the following steps:

[0127] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0128] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0129] 3. After the reaction is completed, filter the graphite slag with suction. Rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then dry it in an oven at 105°C for later use.

[0130] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 1g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 8g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0131] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0132] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0133] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0134] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0135] 9. While stirring, add 3 g of waste activated carbon and 1 g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4 h, and filter and dry after the reaction is complete.

[0136] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 550° C. under nitrogen protection for 3 h, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 8.

[0137] Example 9

[0138] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite. The difference from Example 8 is that the amount of graphene oxide used in step 9 is 2 g. The method comprises the following steps:

[0139] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0140] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0141] 3. After the reaction is completed, filter the graphite slag with suction. Rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then dry it in an oven at 105°C for later use.

[0142] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 1g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 8g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0143] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0144] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0145] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0146] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0147] 9. Under stirring, add 3g of waste activated carbon and 2g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4h, and filter and dry after the reaction is complete.

[0148] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 550° C. under nitrogen protection for 3 h, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 9.

[0149] Example 10

[0150] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite, which differs from Example 8 in that the amount of graphene oxide used in step 9 is 3 g. The method comprises the following steps:

[0151] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0152] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0153] 3. After the reaction is completed, filter the graphite slag with suction. Rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then dry it in an oven at 105°C for later use.

[0154] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 1g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 8g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0155] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0156] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0157] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0158] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0159] 9. Under stirring, add 3g of waste activated carbon and 3g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4h, and filter and dry after the reaction is complete.

[0160] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 550° C. under nitrogen protection for 3 h, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 10.

[0161] Example 11

[0162] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite. The difference from Example 8 is that the amount of graphene oxide used in step 9 is 4 g. The method comprises the following steps:

[0163] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0164] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0165] 3. After the reaction is completed, filter the graphite slag with suction. Rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then dry it in an oven at 105°C for later use.

[0166] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 1g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 8g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0167] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0168] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0169] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0170] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0171] 9. Under stirring, add 3g of waste activated carbon and 4g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4h, and filter and dry after the reaction is complete.

[0172] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 550° C. under nitrogen protection for 3 h, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 11.

[0173] Example 12

[0174] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite, which differs from Example 10 in that the heating temperature in step 10 is 600° C. and includes the following steps:

[0175] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0176] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0177] 3. After the reaction is completed, filter the graphite slag with suction. Rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then dry it in an oven at 105°C for later use.

[0178] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 1g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 8g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0179] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0180] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0181] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0182] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0183] 9. Under stirring, add 3g of waste activated carbon and 3g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4h, and filter and dry after the reaction is complete.

[0184] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 600° C. under nitrogen protection for 3 h, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 12.

[0185] Example 13

[0186] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite, which differs from Example 10 in that the heating temperature in step 10 is 700° C. and includes the following steps:

[0187] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0188] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0189] 3. After the reaction is completed, filter the graphite slag with suction. Rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then dry it in an oven at 105°C for later use.

[0190] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 1g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 8g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0191] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0192] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0193] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0194] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0195] 9. Under stirring, add 3g of waste activated carbon and 3g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4h, and filter and dry after the reaction is complete.

[0196] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 700° C. under nitrogen protection for 3 h, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 13.

[0197] Example 14

[0198] This embodiment provides a method for preparing a high-performance adsorbent from waste lithium battery negative electrode graphite, which differs from Example 10 in that the heating temperature in step 10 is 800° C. and includes the following steps:

[0199] 1. Graphite slag purification and impurity removal: Take the negative electrode graphite slag produced by the wet recovery of waste lithium iron phosphate batteries, dry it in a 105℃ oven for 4 hours, crush it with a crusher, sieve it through a 100-mesh sieve, and keep the sieve underfill for later use;

[0200] 2. Take 100g of the graphite slag treated in step 1 and put it into a beaker. Then add 300mL of 1.7mol / L sulfuric acid to it for pickling. Heat it in a 70℃ water bath and stir the reaction for 4h.

[0201] 3. After the reaction is completed, filter the graphite slag with suction. Rinse the graphite slag with 90°C hot water three times, with 500 mL of water each time; then dry it in an oven at 105°C for later use.

[0202] 4. Take 2g of the graphite obtained in step 3 after impurities are removed and 1g of sodium nitrate and put them into a beaker. Then add 40mL of 98% concentrated sulfuric acid to the beaker and stir thoroughly. Slowly and evenly add 8g of potassium permanganate under 0℃ ice bath and stirring conditions, and react for 2h.

[0203] 5. Place the mixed solution in step 4 in a 90°C water bath and slowly add 60 mL of deionized water. After reacting for 0.5 h, add a small amount of 30% hydrogen peroxide at room temperature until no more bubbles are generated.

[0204] 6. After the above solution was allowed to stand for 0.5 h, it was filtered, and then the filter residue was rinsed with 10 mL of 10% hydrochloric acid under the condition of suction filtration, and then the filter residue was washed with deionized water until it was neutral (pH 6-7), and dried at 105 ° C to obtain the modified graphene oxide, and mechanically ground through a 400 mesh sieve, and the sieve was taken for later use;

[0205] 7. Dry and grind the calcium sulfate residue to below 100 mesh, and grind the waste activated carbon to below 400 mesh for later use;

[0206] 8. Take 5g of the calcium sulfate residue from step 7, add 50g of distilled water and stir to make a slurry, then add 2g of gelatin to the solution, heat it in a water bath to 65°C, and keep it warm for 1h until the gelatin is completely dissolved;

[0207] 9. Under stirring, add 3g of waste activated carbon and 3g of graphene oxide to the above solution in sequence, stir in a water bath at 40°C for 4h, and filter and dry after the reaction is complete.

[0208] 10. The material obtained in step 9 was placed in an atmosphere furnace, heated at 800° C. under nitrogen protection for 3 h, and then cooled to room temperature in a nitrogen atmosphere to obtain a carbon-based modified gypsum adsorbent 14.

[0209] Test example

[0210] 0.1 g of the carbon-based modified gypsum adsorbent obtained in Examples 1-14 above was added to 100 mL of wastewater with a methylene blue concentration of 422.26 mg / L to conduct a dye wastewater adsorption experiment. The adsorption time was 4 h. The adsorbent was compared with an equal amount of negative electrode graphite slag, graphene oxide, calcium sulfate slag and waste activated carbon. The analysis and detection results before and after wastewater treatment are shown in Table 2 below.

[0211] Table 2 Dye wastewater adsorption experimental data

[0212]

[0213]

[0214] Comparison of the results of Examples 1-14 with those of experiments using graphite slag, graphene oxide, calcium sulfate slag, and waste activated carbon alone to adsorb methylene blue wastewater shows that the adsorption performance of the carbon-based modified composite material prepared by the above steps is significantly improved, and the adsorption capacity is significantly increased. With the addition of this composite material, the methylene blue removal efficiency can reach 97.27%, and the adsorption capacity of the composite material can reach 410.74 mg / g.

[0215] From the comparison of the adsorption experiments of graphite slag and graphene oxide, it can be seen that the adsorption capacity of graphite slag is significantly enhanced after purification and oxidation modification.

[0216] From the comparison of the adsorption experiments of Examples 1, 2, and 3, it can be seen that in the preparation of graphene by oxidation of purified graphite slag, the amount of sodium nitrate added affects the adsorption properties of the final composite material, and the best effect is achieved when the mass ratio of purified graphite slag to sodium nitrate is 2:1.

[0217] From the comparison of the adsorption experiments in Examples 2, 4, 5, and 6, it can be seen that the addition of potassium permanganate promotes the oxidative modification of the purified graphite slag. The effect is better when the ratio is 1:4. Continuing to increase the ratio of potassium permanganate, the improvement effect no longer increases significantly.

[0218] From the comparison of Examples 5, 7, and 8, it can be seen that the doping amount of waste activated carbon affects the final adsorption performance, and the best effect is achieved when the ratio of calcium sulfate to waste activated carbon is 5:3.

[0219] From the comparison of Examples 8, 9, 10, and 11, it can be seen that the amount of graphene oxide added is an important factor affecting the adsorption performance of the composite material. When the ratio of calcium sulfate to graphene oxide is 5:3, the adsorption performance of the adsorbent is better. If the ratio of graphene oxide is further increased, the adsorption effect will no longer improve.

[0220] From the comparison of Examples 10, 12, 13 and 14, it can be seen that the adsorption performance of the composite material improves with the increase of the final heating temperature. The best effect is achieved when the temperature is 700°C. When the temperature is further increased, the adsorption effect no longer improves.

[0221] It can be seen that the present invention uses the calcium sulfate slag generated during the neutralization of the synthetic mother liquor of waste battery lithium iron phosphate and the wastewater treatment process as the matrix, loads carbon-based materials such as pretreated graphite slag and waste activated carbon, and then prepares a composite high-efficiency adsorption material through high-temperature modification and activation. This material has good adsorption and decolorization performance for dye wastewater, realizing the resource utilization of waste lithium battery solid waste.

[0222] While the embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above. Various modifications may be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof may be combined with one another unless there is a conflict.

Claims

1. A method for recycling scrapped lithium batteries, characterized in that: The following steps are involved: S1: providing calcium sulfate slag, graphite slag and waste activated carbon, and purifying and modifying the graphite slag in sequence to obtain graphene oxide; S2: adding water to the calcium sulfate slag to prepare a slurry, adding a binder and heating until the binder is completely dissolved, and then adding the waste activated carbon and the graphene oxide to obtain an adsorbent precursor; S3: performing high-temperature desorption on the adsorbent precursor under an inert atmosphere to obtain a gypsum adsorbent.

2. The method according to claim 1, characterized in that Step S1 further includes: making the calcium sulfate slag no coarser than 100 mesh, and making the waste activated carbon and the graphene oxide no coarser than 400 mesh.

3. The method according to claim 1, characterized in that In step S1, the purification includes the following steps: sequentially performing acid washing and hot water washing on the graphite slag.

4. The method according to claim 1, wherein In step S1, the modification includes the following steps: mixing the purified graphite slag with nitrate and acid, adding an oxidant for oxidation under ice bath conditions, adding water for reaction under water bath conditions, then adding a reducing agent at room temperature, performing solid-liquid separation after the reaction is completed, washing and drying the solid phase to obtain the graphene oxide.

5. The method according to claim 4, characterized in that The mass ratio of the graphite slag to the nitrate is 2: (1-3); and / or the oxidant is potassium permanganate, and the mass ratio of the graphite slag to the oxidant is 1: (2-5); and / or the mass ratio of the graphite slag to the water is 1: (30-50).

6. The method according to claim 1, characterized in that In step S2, the binder is at least one of gelatin and polyethylene glycol; and / or the mass of the binder is 10% to 40% of the mass of the calcium sulfate slag.

7. The method according to claim 1, characterized in that In step S2, the mass ratio of the calcium sulfate slag, the waste activated carbon and the graphene oxide is 5:(1-3):(1-4).

8. The method according to claim 1, characterized in that In step S3, the high-temperature desorption temperature is 550-800° C., and the time is 2-4 hours.

9. A gypsum adsorbent prepared by the method according to any one of claims 1 to 8, characterized in that: The invention comprises a calcium sulfate matrix and graphene and activated carbon supported on the calcium sulfate matrix; the porosity of the gypsum adsorbent is 85% to 90%, the pore size distribution is 20 to 100 nm, and the specific surface area is 860 to 900 m 2 / g.

10. Use of the method according to any one of claims 1 to 8 or the gypsum adsorbent according to claim 9 in the treatment of dye wastewater.

Images