A phosphate purification agent for waste battery-based water and its preparation method

Abstract

This invention belongs to the field of adsorbent preparation technology, specifically providing a waste battery-based water phosphate purifier and its preparation method. The preparation method includes the following steps: dissolving zinc and manganese ions from waste batteries in an aqueous phase; adding the organic ligand 2-methylimidazole at room temperature, and simultaneously adding the deprotonating agent triethylamine to promote the synthesis of waste battery-based ZIF-8; further, combining it with lignin and a porogen at high temperature through pyrolysis to synthesize a porous carbon material loaded with waste battery-based ZIF-8 derivatives. The synergistic effect of the zinc and manganese ion adsorption sites in the proposed phosphate purifier and the porous carbon material results in a highly effective removal of phosphate ions from the aquatic environment, representing an economical and feasible method for resource recovery and water pollution control.

Description

Technical Field

[0001] This invention relates to the field of adsorbent preparation technology, specifically to a phosphate purification agent for waste battery water and its preparation method. Background Technology

[0002] Eutrophication is a prevalent water pollution problem in bays, lakes, and rivers. Due to its significant harm and far-reaching impact, it has become a challenging issue in water pollution control. Various types of phosphate-containing wastewater are easily generated in daily production and life, and excessive discharge of phosphate-containing wastewater into water bodies is one of the main causes of eutrophication. Therefore, purifying the phosphate content in phosphate-containing wastewater is crucial for controlling eutrophication.

[0003] Adsorption methods have advantages such as simple operation, large adsorption capacity, low pollution, fast purification speed, and recyclability. At the same time, due to the non-renewable nature of phosphorus and its irreplaceable role in life, phosphorus recovery must be considered during the process of removing phosphate from wastewater. Adsorption methods can achieve the goal of recovering phosphorus resources through desorption treatment after removing phosphate from wastewater. These characteristics make adsorption methods for purifying phosphate in water one of the current research hotspots.

[0004] Waste carbon-zinc-manganese batteries are a type of hazardous waste. If not recycled, they can cause heavy metal pollution and various other forms of pollution. While waste carbon-zinc-manganese batteries contain recyclable resources such as zinc and manganese, the recycling process is complex and costly. Preparing them into adsorbents to purify phosphate in water can achieve the goal of treating waste with waste, but related research is limited, and the performance of adsorbents prepared using existing technologies still needs improvement. Summary of the Invention

[0005] To address the above issues and overcome the shortcomings of existing technologies, this invention provides a phosphate purifier for waste battery-based water treatment and its preparation method. This method directly prepares MOFs materials from elements such as zinc and manganese in waste batteries, avoiding the complex operations of segmented extraction. Furthermore, the MOFs materials prepared from multiple metal ions possess numerous defect structures, providing a large number of adsorption sites. Further, through co-pyrolysis with lignin, porous carbon materials loaded with ZIF-8 derivatives are prepared, which can efficiently adsorb phosphate ions in water, achieving waste-to-water treatment.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention proposes a phosphate purifier for waste battery water, wherein the phosphate purifier comprises the following components in parts by weight: 1-2 parts of waste battery-based ZIF-8, 4-8 parts of pore-forming agent, and 4 parts of lignin.

[0007] Preferably, the method for preparing the waste battery-based ZIF-8 includes the following steps:

[0008] (1) Disassemble a waste battery and place the disassembled material in a 500 mL beaker. Add 450 mL of 0.5 mol / L H2SO4 and place the beaker in an ultrasonic vibrator. Heat the water bath to 60°C while simultaneously vibrating the ultrasonic vibrator. Stir continuously until the mixture is completely dissolved to obtain a solution.

[0009] (2) The solution prepared in step (1) is filtered to obtain a filtrate. The pH of the filtrate is adjusted to 6-7 using 2 mol / L NaOH to obtain a metal ion solution.

[0010] (3) Weigh 4-5 g of 2-methylimidazole and dissolve it in 200 mL of distilled water. Stir to dissolve, add 2-4 mL of deprotonating agent, and mix well to obtain the ligand solution;

[0011] (4) Add the metal ion solution prepared in step (2) to the ligand solution prepared in step (3), stir at 400~600 rpm for 4 h, wash the precipitate three times with ultrapure water, and dry it in an oven at 60℃ for 12 h to obtain waste battery-based ZIF-8.

[0012] Preferably, the waste battery in step (1) is a used No. 5 zinc-manganese battery.

[0013] Preferably, the deprotonating agent in step (3) is triethylamine.

[0014] This invention also provides a method for preparing a phosphate purifier for waste battery-based water, comprising the following steps:

[0015] S1. Weigh 1~2 g of waste battery-based ZIF-8, 4 g of lignin, and 4~8 g of pore-forming agent, grind and mix them evenly in a mortar to obtain a mixture;

[0016] S2. Transfer the mixture prepared in step S1 into a magnetic boat and cover it. Place it in the constant temperature zone of a tube furnace and heat it to 750~850℃ under the continuous protection of nitrogen flow. Heat it at this temperature for 2 hours and then cool it to room temperature to obtain a black product.

[0017] S3. The black product prepared in step S2 is washed three times with 0.5 mol / L dilute hydrochloric acid and distilled water, and then dried in an oven at 80~100℃ for 12 h to obtain the phosphate purifier.

[0018] Preferably, the pore-forming agent in step S1 is potassium carbonate.

[0019] Preferably, in step S2, the nitrogen gas flow rate is 100 mL / min and the heating rate is 5 °C / min.

[0020] The beneficial effects achieved by this invention are as follows:

[0021] Waste zinc-manganese batteries contain abundant zinc, manganese, and other resources, making them highly valuable for utilization. This invention dissolves zinc and manganese ions from waste batteries in an aqueous phase, adds the organic ligand 2-methylimidazole at room temperature, and simultaneously adds the deprotonating agent triethylamine to promote the synthesis of waste battery-based ZIF-8. Zinc ions readily form MOF structures with 2-methylimidazole, while manganese ions, acting as dopant ions, give the synthesized ZIF-8 defect states and irregular structures, effectively utilizing the zinc and manganese resources in waste zinc-manganese batteries. Furthermore, this invention combines the synthesized waste battery-based ZIF-8 with lignin, using potassium carbonate as a pore-forming agent. During pyrolysis, K2CO3 decomposes into K2O and CO2, initiating reactions between K2O and CO2 and carbon to form potassium vapor and carbon monoxide, respectively. When potassium vapor is introduced into the reaction matrix, a porous carbon structure is formed, which has a large porosity and specific surface area. During the pyrolysis process, the structure of the waste battery-based ZIF-8 changes, forming derivatives. This improves stability and allows it to bind tightly with carbon materials. The adsorption sites of zinc and manganese ions work synergistically with the adsorption sites of the porous carbon materials, resulting in a high adsorption capacity for phosphate ions in the aquatic environment. Furthermore, the synthesis process avoids the use of organic solvents, reducing costs and environmental safety risks. This achieves waste-to-waste treatment, making it an economically feasible method for resource recycling and water pollution control. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a macroscopic photograph of the phosphate purifier prepared in Example 1;

[0024] Figure 2 A scanning electron microscope image of the phosphate purifier prepared in Example 1;

[0025] Figure 3 The graph shows the phosphate removal rate of the phosphate purifier prepared in Example 1 at different pH values.

[0026] Figure 4 The graph shows the phosphate removal rate of the phosphate purifier prepared in Example 1 at different times.

[0027] Figure 5 The graph shows the phosphate removal rate of the phosphate purifiers prepared in Examples 1-3 and Comparative Example 1.

[0028] Figure 6 The graph shows the phosphate removal rate of the phosphate purifier prepared in Example 1 during five cycles of use. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0031] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; unless otherwise specified, the experimental materials used in the following embodiments are all purchased from commercial channels.

[0032] Example 1: This example proposes a phosphate purifier for waste battery-based water bodies. The phosphate purifier comprises the following components in parts by weight: 1 part waste battery-based ZIF-8, 4 parts pore-forming agent, and 4 parts lignin.

[0033] The preparation method of the waste battery-based ZIF-8 includes the following steps:

[0034] (1) Disassemble a waste No. 5 zinc-manganese battery, place the disassembled material in a 500 mL beaker, add 450 mL of 0.5 mol / L H2SO4, place the beaker in an ultrasonic vibrator, heat it in a water bath to 60°C while ultrasonically vibrating, and stir continuously until it is completely dissolved to obtain a solution.

[0035] (2) The solution prepared in step (1) is filtered to obtain a filtrate. The pH of the filtrate is adjusted to 6 using 2 mol / L NaOH to obtain a metal ion solution.

[0036] (3) Weigh 4 g of 2-methylimidazole and dissolve it in 200 mL of distilled water. Stir to dissolve, add 4 mL of triethylamine, and mix well to obtain the ligand solution;

[0037] (4) Add the metal ion solution prepared in step (2) to the ligand solution prepared in step (3), stir at 400 rpm for 4 h, wash the precipitate three times with ultrapure water, and dry it in an oven at 60°C for 12 h to obtain waste battery-based ZIF-8.

[0038] This embodiment also provides a method for preparing a waste battery-based water phosphate purification agent, including the following steps:

[0039] S1. Weigh 1 g of waste battery-based ZIF-8, 4 g of lignin, and 4 g of potassium carbonate, grind and mix them evenly in a mortar to obtain a mixture.

[0040] S2. Transfer the mixture prepared in step S1 into a magnetic boat and cover it. Place it in the constant temperature zone of a tube furnace and heat it to 750°C at a rate of 5°C / min under the continuous protection of nitrogen flow of 100 mL / min. Heat it at this temperature for 2 h and then cool it to room temperature to obtain a black product.

[0041] S3. The black product prepared in step S2 is washed three times with 0.5 mol / L dilute hydrochloric acid and distilled water, and then dried in an oven at 80°C for 12 h to obtain the phosphate purifier.

[0042] Example 2: This example proposes a phosphate purifier for waste battery-based water bodies. The phosphate purifier comprises the following components in parts by weight: 2 parts of waste battery-based ZIF-8, 8 parts of pore-forming agent, and 4 parts of lignin.

[0043] The preparation method of the waste battery-based ZIF-8 includes the following steps:

[0044] (1) Disassemble a waste No. 5 zinc-manganese battery, place the disassembled material in a 500 mL beaker, add 450 mL of 0.5 mol / L H2SO4, place the beaker in an ultrasonic vibrator, heat it in a water bath to 60°C while ultrasonically vibrating, and stir continuously until it is completely dissolved to obtain a solution.

[0045] (2) The solution prepared in step (1) is filtered to obtain a filtrate. The pH of the filtrate is adjusted to 7 using 2 mol / L NaOH to obtain a metal ion solution.

[0046] (3) Weigh 5 g of 2-methylimidazole and dissolve it in 200 mL of distilled water. Stir to dissolve, add 2 mL of triethylamine, and mix well to obtain the ligand solution;

[0047] (4) Add the metal ion solution prepared in step (2) to the ligand solution prepared in step (3), stir at 600 rpm for 4 h, wash the precipitate three times with ultrapure water, and dry it in an oven at 60°C for 12 h to obtain waste battery-based ZIF-8.

[0048] This embodiment also provides a method for preparing a waste battery-based water phosphate purification agent, including the following steps:

[0049] S1. Weigh 2 g of waste battery-based ZIF-8, 4 g of lignin, and 8 g of potassium carbonate, grind and mix them evenly in a mortar to obtain a mixture.

[0050] S2. Transfer the mixture prepared in step S1 into a magnetic boat and cover it. Place it in the constant temperature zone of a tube furnace and heat it to 850°C at a rate of 5°C / min under the continuous protection of nitrogen flow of 100 mL / min. Heat it at this temperature for 2 h and then cool it to room temperature to obtain a black product.

[0051] S3. The black product prepared in step S2 is washed three times with 0.5 mol / L dilute hydrochloric acid and distilled water, and then dried in an oven at 100℃ for 12 h to obtain the phosphate purifier.

[0052] Example 3: This example proposes a phosphate purifier for waste battery-based water bodies. The phosphate purifier comprises the following components in parts by weight: 1.5 parts of waste battery-based ZIF-8, 6 parts of pore-forming agent, and 4 parts of lignin.

[0053] The preparation method of the waste battery-based ZIF-8 includes the following steps:

[0054] (1) Disassemble a waste No. 5 zinc-manganese battery, place the disassembled material in a 500 mL beaker, add 450 mL of 0.5 mol / L H2SO4, place the beaker in an ultrasonic vibrator, heat it in a water bath to 60°C while ultrasonically vibrating, and stir continuously until it is completely dissolved to obtain a solution.

[0055] (2) The solution prepared in step (1) is filtered to obtain a filtrate. The pH of the filtrate is adjusted to 6.5 using 2 mol / L NaOH to obtain a metal ion solution.

[0056] (3) Weigh 4.5 g of 2-methylimidazole and dissolve it in 200 mL of distilled water. Stir to dissolve, add 3 mL of triethylamine, and mix well to obtain the ligand solution;

[0057] (4) Add the metal ion solution prepared in step (2) to the ligand solution prepared in step (3), stir at 500 rpm for 4 h, wash the precipitate three times with ultrapure water, and dry it in an oven at 60°C for 12 h to obtain waste battery-based ZIF-8.

[0058] This embodiment also provides a method for preparing a waste battery-based water phosphate purification agent, including the following steps:

[0059] S1. Weigh 1.5 g of waste battery-based ZIF-8, 4 g of lignin, and 6 g of potassium carbonate, grind and mix them evenly in a mortar to obtain a mixture;

[0060] S2. Transfer the mixture prepared in step S1 into a magnetic boat and cover it. Place it in the constant temperature zone of a tube furnace and heat it to 800°C at a rate of 5°C / min under the continuous protection of nitrogen flow of 100 mL / min. Heat it at this temperature for 2 h and then cool it to room temperature to obtain a black product.

[0061] S3. The black product prepared in step S2 is washed three times with 0.5 mol / L dilute hydrochloric acid and distilled water, and then dried in an oven at 80~100℃ for 12 h to obtain the phosphate purifier.

[0062] Comparative Example 1: This comparative example proposes a phosphate purifier for waste battery water bodies. The only difference between this example and Example 1 is that no porogen is added during the synthesis of the phosphate purifier. The other components, component contents, and experimental steps are the same as in Example 1. The phosphate purifier includes the following components in parts by weight: 1 part waste battery-based ZIF-8 and 4 parts lignin.

[0063] The preparation method of the waste battery-based ZIF-8 includes the following steps:

[0064] (1) Disassemble a waste No. 5 zinc-manganese battery, place the disassembled material in a 500 mL beaker, add 450 mL of 0.5 mol / L H2SO4, place the beaker in an ultrasonic vibrator, heat it in a water bath to 60°C while ultrasonically vibrating, and stir continuously until it is completely dissolved to obtain a solution.

[0065] (2) The solution prepared in step (1) is filtered to obtain a filtrate. The pH of the filtrate is adjusted to 6 using 2 mol / L NaOH to obtain a metal ion solution.

[0066] (3) Weigh 4 g of 2-methylimidazole and dissolve it in 200 mL of distilled water. Stir to dissolve, add 4 mL of triethylamine, and mix well to obtain the ligand solution;

[0067] (4) Add the metal ion solution prepared in step (2) to the ligand solution prepared in step (3), stir at 400 rpm for 4 h, wash the precipitate three times with ultrapure water, and dry it in an oven at 60°C for 12 h to obtain waste battery-based ZIF-8.

[0068] This comparative example also provides a method for preparing a waste battery-based water phosphate purification agent, including the following steps:

[0069] S1. Weigh 1 g of waste battery-based ZIF-8 and 4 g of lignin, grind and mix them evenly in a mortar to obtain a mixture;

[0070] S2. Transfer the mixture prepared in step S1 into a magnetic boat and cover it. Place it in the constant temperature zone of a tube furnace and heat it to 750°C at a rate of 5°C / min under the continuous protection of nitrogen flow of 100 mL / min. Heat it at this temperature for 2 h and then cool it to room temperature to obtain a black product.

[0071] S3. The black product prepared in step S2 is washed three times with 0.5 mol / L dilute hydrochloric acid and distilled water, and then dried in an oven at 80°C for 12 h to obtain the phosphate purifier.

[0072] Experimental Example 1: The macroscopic morphology of the phosphate purifier prepared in Example 1 was observed, and its microscopic morphology was observed by scanning electron microscopy.

[0073] Figure 1 The figure shows a macroscopic image of the phosphate purifier prepared in Example 1. As shown, the phosphate purifier prepared by high-temperature pyrolysis has a blocky structure and can be observed to have a porous structure with the naked eye. Figure 2 The image shows a scanning electron microscope (SEM) image of the phosphate purifier prepared in Example 1. As shown in the figure, a large number of MOF pyrolysis derivatives are attached to the porous carbon surface, namely, the battery-based ZIF-8 pyrolysis loaded on the porous carbon surface, which improves the stability of the material and indicates the successful preparation of the phosphate purifier of the present invention.

[0074] Experimental Example 2: The effect of pH on phosphate removal rate:

[0075] In a 250 mL Erlenmeyer flask, the amount of phosphate purifying agent prepared in Example 1 was 100 mg, the amount of phosphate-containing simulated wastewater was 120 mL, and the initial concentration of phosphate-containing simulated wastewater was 10 mg / L. The pH value was adjusted to 2, 3, 4, 5, 6, 7, 8, and 9, respectively. The mixture was kept at 25°C and shaken for 2 hours. The supernatant was taken and filtered. 1 mL of the filtrate was taken and its absorbance was measured. The removal rate at different pH values ​​was calculated.

[0076] Detection of phosphate: Add the sample to be tested into a 50 mL colorimetric tube. Accurately pipette 1 mL of 10% ascorbic acid solution into the colorimetric tube and mix well. After waiting for 30 seconds, accurately pipette 2 mL of molybdate solution into the colorimetric tube. Mix thoroughly at room temperature and let stand for 15 minutes. After standing, pour an appropriate amount of the solution in the colorimetric tube into a 10 mm cuvette. Adjust the wavelength of the visible spectrophotometer to 700 nm. Using a zero-concentration phosphate standard solution as a blank reference, measure the absorbance of the solutions in other colorimetric tubes. Calculate the phosphate concentration of the sample using the standard curve method.

[0077] Phosphate removal rate (%) of phosphate purifier = [(initial phosphate concentration - phosphate sample concentration) / initial phosphate concentration] * 100%.

[0078] Figure 3 The figure shows the phosphate removal rate of the phosphate purifier prepared in Example 1 at different pH values. The phosphate purifier showed the highest phosphate removal rate at pH 5. The phosphate purifier contains metal adsorption sites and porous carbon adsorption sites, exhibiting excellent phosphate removal performance. At around pH 2, phosphate mainly exists in the form of H3PO4, with a lower removal rate. At around pH 5, phosphate mainly exists in the form of H2PO4. - The removal rate is relatively high; as the pH gradually increases, HPO4... 2- Gradually taking the dominant position, but OH in the solution - The amount of ions gradually increases, competing with phosphate for adsorption. Therefore, the optimal adsorption pH is set to 5.

[0079] Experimental Example 3: Effect of Time on Phosphate Removal Rate: In a 250 mL Erlenmeyer flask, the amount of phosphate purifying agent prepared in Example 1 was 100 mg, the amount of phosphate-containing simulated wastewater was 120 mL, and the initial concentration of phosphate-containing simulated wastewater was 10 mg / L. The pH value was adjusted to 5, and the mixture was kept at 25℃ and shaken for 5 min, 10 min, 30 min, 60 min, 80 min, 120 min, and 180 min. The supernatant was filtered, and 1 mL of the filtrate was taken to measure its absorbance. The phosphate removal rate at different times was calculated.

[0080] Figure 4 The figure shows the phosphate removal rate of the phosphate purifier prepared in Example 1 at different times. As shown in the figure, the phosphate purifier has a fast adsorption rate of phosphate, and the removal rate can reach 96.2% in 60 minutes, which is highly efficient. This is because the phosphate purifier contains metal ion adsorption sites, which use electrostatic attraction to quickly adsorb and remove negatively charged phosphate.

[0081] Experimental Example 4: In a 250 mL Erlenmeyer flask, 100 mg of the phosphate purifying agent prepared in Examples 1-3 and Comparative Example 1 was used, along with 120 mL of simulated wastewater containing phosphate ions. The initial concentration of the simulated wastewater containing phosphate ions was 10 mg / L. The pH was adjusted to 5, and the mixture was kept at 25°C and shaken for 2 hours. The supernatant was collected and filtered, and 1 mL of the filtrate was taken to measure its absorbance. The removal rate of different implementation methods was calculated.

[0082] Figure 5The figure shows the removal rate of phosphate ions by the phosphate purifiers prepared in Examples 1-3 and Comparative Example 1. As shown in the figure, the phosphate purifiers prepared in Examples 1-3 can completely remove phosphate ions after 120 min of treatment. The phosphate purifier prepared in Comparative Example 1 has a phosphate removal rate of 78.2% after 120 min of treatment. This indicates that the pore-forming effect of potassium carbonate can improve the adsorption performance of the phosphate purifier to a certain extent. However, the main adsorption effect comes from the metal ions recovered from waste zinc-manganese batteries. This shows the successful preparation of the waste battery-based water phosphate purifier provided by the present invention.

[0083] Experimental Example 5: Study on Recyclability: 100 mg of the phosphate purifier prepared in Example 1 was added to a 250 mL Erlenmeyer flask. 120 mL of simulated wastewater containing phosphate was added, with an initial concentration of 10 mg / L. The pH was adjusted to 5, and the mixture was kept at 25°C and shaken for 2 hours. The phosphate purifier was collected, and phosphate was desorbed using 0.5 mol / L NaOH solution. The phosphate purifier was then washed with water until neutral. The above adsorption and desorption steps were repeated five times, and samples were taken to analyze the phosphate removal rate each time.

[0084] Figure 6 The figure shows the removal rate of phosphate ions by the phosphate purifier prepared in Example 1 after five cycles of use. As shown in the figure, although the removal rate of phosphate ions by the phosphate purifier decreased after five adsorption and desorption cycles, it still exceeded 85%, indicating high stability. Therefore, the phosphate purifier proposed in this invention has great potential for practical application in removing phosphate ions from aquatic environments.

[0085] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0086] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A phosphate purification agent for waste battery-based water, characterized in that, The phosphate purifier comprises the following components in parts by weight: 1-2 parts of waste battery-based ZIF-8, 4-8 parts of pore-forming agent, and 4 parts of lignin; The preparation method of the waste battery-based ZIF-8 includes the following steps: (1) Disassemble a waste battery and place the disassembled material in a 500 mL beaker. Add 450 mL of 0.5 mol / L H2SO4 and place the beaker in an ultrasonic vibrator. Heat the water bath to 60°C while simultaneously vibrating the ultrasonic vibrator. Stir continuously until the mixture is completely dissolved to obtain a solution. (2) The solution prepared in step (1) is filtered to obtain a filtrate. The pH of the filtrate is adjusted to 6-7 using 2 mol / L NaOH to obtain a metal ion solution. (3) Weigh 4-5 g of 2-methylimidazole and dissolve it in 200 mL of distilled water. Stir to dissolve, add 2-4 mL of deprotonating agent, and mix well to obtain the ligand solution; (4) Add the metal ion solution prepared in step (2) to the ligand solution prepared in step (3), stir at 400~600 rpm for 4 h, wash the precipitate three times with ultrapure water, and dry it in an oven at 60℃ for 12 h to obtain waste battery-based ZIF-8. The waste battery in step (1) is a used No. 5 zinc-manganese battery; The deprotonating agent in step (3) is triethylamine; The preparation of the waste battery-based water phosphate purification agent includes the following steps: S1. Weigh 1~2 g of waste battery-based ZIF-8, 4 g of lignin, and 4~8 g of pore-forming agent, grind and mix them evenly in a mortar to obtain a mixture; S2. Transfer the mixture prepared in step S1 into a magnetic boat and cover it. Place it in the constant temperature zone of a tube furnace and heat it to 750~850℃ under the continuous protection of nitrogen flow. Heat it at this temperature for 2 hours and then cool it to room temperature to obtain a black product. S3. The black product prepared in step S2 is washed three times with 0.5 mol / L dilute hydrochloric acid and distilled water, and then dried in an oven at 80~100℃ for 12 h to obtain phosphate purifier. The pore-forming agent in step S1 is potassium carbonate; In step S2, the nitrogen gas flow rate is 100 mL / min, and the heating rate is 5 °C / min.

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