Method for synthesizing water treatment material by using phosphate tailings

Abstract

The invention provides a method for synthesizing a water treatment material by using phosphate tailings, the water treatment material has a core-shell structure, the core layer is carboxymethyl chitosan aerogel, the shell layer is a two-dimensional network generated by a copolymerization reaction of oxalic anhydride and methyl acrylate, the carboxymethyl chitosan aerogel is coated with a PVP (Polyvinyl Pyrrolidone) grafted porous phosphate tailing leaching material. The invention provides a method for synthesizing a water treatment material by utilizing phosphate tailings, which achieves the purpose of efficiently removing organic matters in water while realizing the resource utilization of the phosphate tailings.

Description

Technical Field

[0001] The present invention relates to the fields of hazardous waste treatment and water treatment, and specifically to the recycling and reuse of phosphorus tailings. Background Art

[0002] Phosphorus tailings refer to solid wastes generated during the development or production of phosphate rock. With the continuous development of our country, the demand for phosphorus is increasing, and the demand for phosphate rock mining is also increasing. During the process of mining or production, more and more phosphorus tailings will be produced. In order to convert this industrial waste into reusable resources, it is crucial to develop and implement simple and cost-effective purification technologies. According to statistics, most of the tailings during the development or production of phosphate rock will be piled up in tailing ponds or farmlands, and a part of them is used for filling. Whether it is used for filling or piled up in tailing ponds, it is a waste of phosphorus resources in them, not only occupying resources, but also the harmful substances in them will cause serious pollution to the environment.

[0003] Phosphorus tailings contain a large amount of impurity metal elements, such as calcium, magnesium and other elements, and also contain a small amount of elements such as iron and aluminum. If not treated, it will cause environmental pollution. However, on the other hand, if phosphorus tailings are used as raw materials to manufacture adsorbents, these small amounts of various types of elements can be in-situ doped into the adsorbents, which has a positive effect on removing organic substances. Patent CN2014107233233 mentions an aluminum-doped magnetic adsorbent, which has the characteristic of large adsorption capacity. The above several technical solutions strongly prove that metal doping can strongly improve the performance of the adsorbent.

[0004] Therefore, in order to achieve efficient adsorption of organic substances, there is an urgent need for a new technology that can develop and utilize phosphorus tailings to prepare multi-element composite materials through a simple process. Through this technology, it can also promote the high-value utilization of phosphorus tailings and achieve the goal of treating waste with waste. Summary of the Invention

[0005] Technical problems to be solved: The purpose of the present invention is to provide a method for synthesizing a water treatment material using phosphorus tailings, which can achieve the goal of resource utilization of phosphorus tailings and efficiently remove organic substances in water at the same time.

[0006] Technical solution: A method for synthesizing a water treatment material using phosphorus tailings, characterized in that: the water treatment material has a core-shell structure, its core layer is carboxymethyl chitosan aerogel, its shell layer is a two-dimensional network formed by the copolymerization reaction of oxalic anhydride and methyl acrylate, and the carboxymethyl chitosan aerogel is coated with a PVP-grafted porous phosphorus tailings leaching material.

[0007] Preferably, the method includes the following steps: S1. Add a crosslinking agent to maleic anhydride, heat and stir at 40 - 60 °C for 20 - 40 min to obtain a homogeneous solution; S2. Add methyl acrylate and carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel to the homogeneous solution, perform ultrasonic treatment and then magnetic stirring; S3. Add an initiator and react at 60 - 80 °C for 30 - 50 min under a nitrogen atmosphere to obtain a core - shell structure aerogel.

[0008] Preferably, the crosslinking agent is one or more of N,N - methylenebisacrylamide, divinylbenzene and triallyl isocyanurate, the initiator is one or more of ammonium persulfate, sodium persulfate and benzoyl peroxide, the molar ratio of the crosslinking agent, maleic anhydride, methyl propionate and the initiator is 0.2 - 0.4:1 - 3:1 - 4:0.02 - 0.05, and the mass ratio of the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel to methyl acrylate is 1 - 3:2 - 5.

[0009] Preferably, the preparation method of the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel in S2 includes the following steps: S11. Add the PVP grafted porous phosphorus tailing leaching material to a 5 - 15 wt% carboxymethyl chitosan solution and perform ultrasonic dispersion to obtain a suspension; S12. Add a 10 - 20 wt% glutaraldehyde solution to the suspension and stir for 30 - 60 min; S13. Freeze - dry the solution at - 30 - - 20 °C for 30 - 50 h to obtain the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel.

[0010] Preferably, the mass fraction of the PVP grafted porous phosphorus tailing leaching material is 5 - 10 wt% of the carboxymethyl chitosan, and the volume ratio of the glutaraldehyde solution to the carboxymethyl chitosan solution is 2 - 6:25 - 40.

[0011] Preferably, the preparation method of the PVP grafted porous phosphorus tailing leaching material in S11 includes the following steps: S21. Add phosphorus tailings to an acidic dissolving agent, heat, stir and filter to obtain a dissolved solution A; S22. Mix the dissolved solution A with an alkaline solution, stir, filter and ball - mill to obtain a phosphorus tailing leaching material; S23. Heat - treat the phosphorus tailing leaching material at 800 - 1000 °C for 4 - 6 h, and mix the calcined phosphorus tailing leaching material and the uncalcined phosphorus tailing leaching material according to a mass ratio of 1 - 4:3 - 10 to obtain a porous phosphorus tailing leaching material; S24. Add the porous phosphorus tailings leaching material, FeCl 2 and PVP into water according to the mass ratio of 4 - 7: 0.005 - 0.008: 1 - 3, and obtain a homogeneous suspension through stirring and ultrasonic dispersion; S25. Add dilute hydrochloric acid with a concentration of 0.1 - 0.5 mol / L to the homogeneous suspension to adjust the pH to 2 - 4, and add hydrogen peroxide for titration; S26. Let the solution obtained in S24 stand for 3 - 6 h, centrifuge, filter and wash, and then carry out ball milling to obtain a PVP - grafted porous phosphorus tailings leaching material with a particle size of 10 - 25 μm.

[0012] Preferably, the acidic solvent in S21 is one or more of boric acid, citric acid, oxalic acid, acetic acid and hydrochloric acid, the concentration of the acidic solvent is 0.5 - 1.5 mol / L, and the mass ratio of the phosphorus tailings to the acidic solvent is 1: 5 - 10.

[0013] Preferably, the basic solvent in S22 is one or more of sodium hydroxide, potassium hydroxide, ammonia water and sodium bicarbonate, the concentration of the basic solvent is 1.5 - 3 mol / L, and the volume ratio of the solution A to the basic solution is 1 - 3: 4 - 10.

[0014] Preferably, the mass fraction of the homogeneous suspension in S24 is 2 - 8 wt%.

[0015] Beneficial effects: 1. In the present invention, the porosity and specific surface area of the phosphorus tailings leaching material (a mixture of calcium hydroxide and magnesium hydroxide) are increased through high - temperature treatment of the phosphorus tailings leaching material. The heat - treated phosphorus tailings leaching material and the non - heat - treated phosphorus tailings leaching material are mixed to obtain a phosphorus tailings leaching material with a hierarchical pore structure, and the specific surface area and porosity of the phosphorus tailings leaching material can be regulated by the time and temperature of high - temperature treatment, providing channels for ion transport during the adsorption process. PVP is a water - soluble polymer. Grafting PVP onto the surface of the phosphorus tailings leaching material, the steric hindrance formed on the surface can reduce the entanglement between the phosphorus tailings leaching materials, making the phosphorus tailings leaching materials more likely to contact dye molecules, and providing more adsorption sites, thereby forming a stronger interaction with dye molecules and enhancing the adsorption capacity; 2. In the present invention, the aerogel prepared from carboxymethyl chitosan and PVP-grafted porous phosphorus tailings leaching material. The hydrogen bond force between the hydroxyl group in PVP and the amino group in carboxymethyl chitosan enhances the physical cross-linking. Moreover, the PVP-grafted porous phosphorus tailings leaching material can be regarded as a structural reinforcing filler to improve the mechanical properties of the aerogel. And the aerogel, as a three-dimensional adsorption material, has a high specific surface area and porosity. Additionally, there are functional groups such as carboxymethyl, amino, and hydroxyl groups on the surface of carboxymethyl chitosan, and these functional groups ionize in water to generate anions, thereby improving the adsorption efficiency of cationic dyes; 3. In the present invention, a two-dimensional network is formed on the surface of the aerogel through copolymerization reaction to form an aerogel with a core-shell structure. The two-dimensional network generated by the copolymerization reaction ionizes in water to generate anions, which is beneficial to the adsorption of cationic dyes. And the two-dimensional network uniformly coats the surface of the aerogel, promoting the diffusion of dyes to the surface of the aerogel. Subsequently, the dyes penetrate into the interior of the aerogel through various pores, and the shell layer and the core layer complement each other to achieve efficient adsorption of dyes. Detailed implementation manners

[0016] The present invention will be further described below in conjunction with embodiments. The following embodiments are explanations of the present invention, and the present invention is not limited to the following embodiments:

[0017] Embodiment 1 A method for synthesizing a water treatment material using phosphorus tailings, the method comprising the following steps: S1. Add N,N-methylenebisacrylamide to succinic anhydride, heat and stir at 40 °C for 20 min to obtain a homogeneous solution; S2. Add methyl acrylate and carboxymethyl chitosan / PVP-grafted porous phosphorus tailings leaching material aerogel to the homogeneous solution. The mass ratio of carboxymethyl chitosan / PVP-grafted porous phosphorus tailings leaching material aerogel to methyl acrylate is 1:2, and after ultrasonic treatment, stir magnetically; S3. Add ammonium persulfate. The molar ratio of N,N-methylenebisacrylamide, succinic anhydride, methyl acrylate and ammonium persulfate is 0.2:1:1:0.02, and react at 60 °C for 30 min under a nitrogen atmosphere to obtain a core-shell structure aerogel.

[0018] Among them, the preparation method of the carboxymethyl chitosan / PVP-grafted porous phosphorus tailings leaching material aerogel in S2 includes the following steps: S11. Add the PVP-grafted porous phosphorus tailings leaching material to a 5 wt% carboxymethyl chitosan solution. The mass fraction of the PVP-grafted porous phosphorus tailings leaching material is 5 wt% of that of carboxymethyl chitosan, and ultrasonic disperse to obtain a suspension; S12. Add a glutaraldehyde solution with a mass fraction of 10 wt% to the suspension. The volume ratio of the glutaraldehyde solution to the carboxymethyl chitosan solution is 2:25, and stir for 30 min. S13. Freeze-dry the solution at -30 °C for 30 h to obtain a carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel.

[0019] Among them, the preparation method of the PVP grafted porous phosphorus tailing leaching material in S11 includes the following steps: S21. Add phosphorus tailings to a 0.5 mol / L boric acid solution. The mass ratio of phosphorus tailings to the boric acid solution is 1:5. After heating, stirring and filtering, a dissolution solution A is obtained. S22. Mix the dissolution solution A with a sodium hydroxide solution with a concentration of 1.5 mol / L. The volume ratio of the dissolution solution A to the sodium hydroxide solution is 1:4. After stirring, filtering and ball milling, a phosphorus tailing leaching material is obtained. S23. Heat-treat the phosphorus tailing leaching material at 800 °C for 4 h, and mix the calcined phosphorus tailing leaching material and the uncalcined phosphorus tailing leaching material according to a mass ratio of 1:3 to obtain a porous phosphorus tailing leaching material. S24. Add the porous phosphorus tailing leaching material, FeCl 2 and PVP to water according to a mass ratio of 4:0.005:1. After stirring and ultrasonic dispersion, a homogeneous suspension with a mass fraction of 2 wt% is obtained. S25. Add dilute hydrochloric acid with a concentration of 0.1 - 0.5 mol / L to the homogeneous suspension to adjust the pH to 2, and add hydrogen peroxide for titration. S26. Let the solution obtained in S24 stand for 3 - 6 h, centrifuge, filter and wash, and then perform ball milling to obtain a PVP grafted porous phosphorus tailing leaching material with a particle size of 10 - 25 μm.

[0020] Example 2 A method for synthesizing a water treatment material using phosphorus tailings, the method includes the following steps: S1. Add triallyl isocyanurate to succinic anhydride, heat and stir at 60 °C for 40 min to obtain a homogeneous solution. S2. Add methyl acrylate and carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel to the homogeneous solution. The mass of the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel to methyl acrylate is 3:5. After ultrasonic treatment, perform magnetic stirring. S3. Add sodium persulfate. The molar ratio of N,N - methylenebisacrylamide, succinic anhydride, methyl acrylate and ammonium persulfate is 0.4:3:4:0.05. React at 80 °C for 50 min under a nitrogen atmosphere to obtain a core - shell structure aerogel.

[0021] Among them, the preparation method of the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel in S2 includes the following steps: S11. Add the PVP grafted porous phosphorus tailing leaching material into a carboxymethyl chitosan solution with a mass fraction of 15 wt%, where the mass fraction of the PVP grafted porous phosphorus tailing leaching material is 10 wt% of that of the carboxymethyl chitosan, and ultrasonically disperse to obtain a suspension; S12. Add a glutaraldehyde solution with a mass fraction of 20 wt% into the suspension, and the volume ratio of the glutaraldehyde solution to the carboxymethyl chitosan solution is 6:40, and stir for 60 min; S13. Freeze-dry the solution at -20 °C for 50 h to obtain the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel.

[0022] Among them, the preparation method of the PVP grafted porous phosphorus tailing leaching material in S11 includes the following steps: S21. Add phosphorus tailings into a 1.5 mol / L boric acid solution, and the mass ratio of the phosphorus tailings to the boric acid solution is 1:10. After heating, stirring and filtering, a dissolved solution A is obtained; S22. Mix the dissolved solution A with a sodium hydroxide solution with a concentration of 3 mol / L, and the volume ratio of the dissolved solution A to the sodium hydroxide solution is 1:4. After stirring, filtering and ball milling, a phosphorus tailing leaching material is obtained; S23. Heat-treat the phosphorus tailing leaching material at 1000 °C for 6 h, and mix the calcined phosphorus tailing leaching material and the uncalcined phosphorus tailing leaching material according to a mass ratio of 4:10 to obtain a porous phosphorus tailing leaching material; S24. Add the porous phosphorus tailing leaching material, FeCl 2 and PVP into water according to a mass ratio of 4:0.005:1, and after stirring and ultrasonic dispersion, a homogeneous suspension with a mass fraction of 8 wt% is obtained; S25. Add dilute hydrochloric acid with a concentration of 0.5 mol / L to the homogeneous suspension to adjust the pH to 4, and add hydrogen peroxide for titration; S26. Let the solution obtained in S24 stand for 6 h, centrifuge, filter and wash, and then perform ball milling to obtain a PVP grafted porous phosphorus tailing leaching material with a particle size of 25 μm.

[0023] Example 3 A method for synthesizing a water treatment material using phosphorus tailings, the method includes the following steps: S1. Add triallyl isocyanurate into succinic anhydride, heat and stir at 60 °C for 40 min to obtain a homogeneous solution; S2. Add methyl acrylate and the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel to the homogeneous solution. The mass ratio of the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel to methyl acrylate is 3:5. After ultrasonic treatment, stir magnetically. S3. Add sodium persulfate, N,N-methylenebisacrylamide, and acetic anhydride. The molar ratio of methyl acrylate to ammonium persulfate is 0.4:3:4:0.05. React at 70 °C for 40 min under a nitrogen atmosphere to obtain a core-shell structured aerogel.

[0024] Among them, the preparation method of the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel in S2 includes the following steps: S11. Add the PVP grafted porous phosphorus tailing leaching material to a 10 wt% carboxymethyl chitosan solution. The mass fraction of the PVP grafted porous phosphorus tailing leaching material is 10 wt% of that of carboxymethyl chitosan, and disperse it by ultrasonic treatment to obtain a suspension. S12. Add a 16 wt% glutaraldehyde solution to the suspension. The volume ratio of the glutaraldehyde solution to the carboxymethyl chitosan solution is 6:40, and stir for 60 min. S13. Freeze-dry the solution at -25 °C for 45 h to obtain the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel.

[0025] Among them, the preparation method of the PVP grafted porous phosphorus tailing leaching material in S11 includes the following steps: S21. Add phosphorus tailings to a 1.0 mol / L boric acid solution. The mass ratio of phosphorus tailings to the boric acid solution is 1:10. After heating, stirring, and filtering, obtain a dissolved solution A. S22. Mix the dissolved solution A with a 3 mol / L sodium hydroxide solution. The volume ratio of the dissolved solution A to the sodium hydroxide solution is 1:4. After stirring, filtering, and ball milling, obtain the phosphorus tailing leaching material. S23. Heat-treat the phosphorus tailing leaching material at 850 °C for 6 h. Mix the calcined phosphorus tailing leaching material with the uncalcined phosphorus tailing leaching material according to a mass ratio of 4:10 to obtain the porous phosphorus tailing leaching material. S24. Add the porous phosphorus tailing leaching material, FeCl 2 and PVP to water according to a mass ratio of 4:0.005:1. After stirring and ultrasonic dispersion, obtain an 8 wt% homogeneous suspension. S25. Add a 0.5 mol / L dilute hydrochloric acid to the homogeneous suspension to adjust the pH to 3, and add hydrogen peroxide for titration. S26. Let the solution obtained in S24 stand for 6 h, then centrifuge, filter and wash it, and subsequently carry out ball milling to obtain a PVP-grafted porous phosphorus tailing leaching material with a particle size of 25 μm.

[0026] Example 4 A method for synthesizing a water treatment material using phosphorus tailings, the method comprising the following steps: S1. Add triallyl isocyanurate to succinic anhydride, heat and stir at 55 °C for 35 min to obtain a homogeneous solution; S2. Add methyl acrylate and a carboxymethyl chitosan / PVP-grafted porous phosphorus tailing leaching material aerogel to the homogeneous solution. The mass ratio of the carboxymethyl chitosan / PVP-grafted porous phosphorus tailing leaching material aerogel to methyl acrylate is 2:5. After ultrasonic treatment, stir magnetically; S3. Add ammonium persulfate, N,N'-methylenebisacrylamide. The molar ratio of succinic anhydride, methyl acrylate and ammonium persulfate is 0.4:3:4:0.05. React at 80 °C for 50 min under a nitrogen atmosphere to obtain a core-shell structure aerogel.

[0027] Among them, the preparation method of the carboxymethyl chitosan / PVP-grafted porous phosphorus tailing leaching material aerogel in S2 comprises the following steps: S11. Add the PVP-grafted porous phosphorus tailing leaching material to a 8 wt% carboxymethyl chitosan solution. The mass fraction of the PVP-grafted porous phosphorus tailing leaching material is 7 wt% of that of carboxymethyl chitosan, and ultrasonically disperse to obtain a suspension; S12. Add a 15 wt% glutaraldehyde solution to the suspension. The volume ratio of the glutaraldehyde solution to the carboxymethyl chitosan solution is 6:40, and stir for 60 min; S13. Freeze-dry the solution at -20 °C for 50 h to obtain a carboxymethyl chitosan / PVP-grafted porous phosphorus tailing leaching material aerogel.

[0028] Among them, the preparation method of the PVP-grafted porous phosphorus tailing leaching material in S11 comprises the following steps: S21. Add phosphorus tailings to a 1.2 mol / L boric acid solution. The mass ratio of phosphorus tailings to boric acid solution is 1:10. After heating, stirring and filtering, obtain a dissolved solution A; S22. Mix the dissolved solution A with a 2 mol / L sodium hydroxide solution. The volume ratio of the dissolved solution A to the sodium hydroxide solution is 2:7. After stirring, filtering and ball milling, obtain a phosphorus tailing leaching material; S23. Heat-treat the phosphorus tailing leaching material at 1000 °C for 6 h, and mix the calcined phosphorus tailing leaching material and the uncalcined phosphorus tailing leaching material according to a mass ratio of 3:10 to obtain a porous phosphorus tailing leaching material; S24. Add the porous phosphorus tailings leaching material, FeCl 2 and PVP to water at a mass ratio of 4:0.005:1, and obtain a homogeneous suspension with a mass fraction of 8 wt% through stirring and ultrasonic dispersion; S25. Add dilute hydrochloric acid with a concentration of 0.4 mol / L to the homogeneous suspension to adjust the pH to 2, and add hydrogen peroxide for titration; S26. Let the solution obtained in S24 stand for 6 h, centrifuge, filter and wash, and then carry out ball milling to obtain PVP-grafted porous phosphorus tailings leaching material with a particle size of 25 μm.

[0029] Example 5 A method for synthesizing a water treatment material using phosphorus tailings, the method comprising the following steps: S1. Add triallyl isocyanurate to ethylenedioxyanhydride, heat and stir at 45 °C for 30 min to obtain a homogeneous solution; S2. Add methyl acrylate and carboxymethyl chitosan / PVP-grafted porous phosphorus tailings leaching material aerogel to the homogeneous solution, the mass of the carboxymethyl chitosan / PVP-grafted porous phosphorus tailings leaching material aerogel and methyl acrylate is 2:5, and carry out ultrasonic treatment followed by magnetic stirring; S3. Add sodium persulfate, N,N-methylenebisacrylamide, the molar ratio of ethylenedioxyanhydride, methyl acrylate and ammonium persulfate is 0.4:3:4:0.05, react at 80 °C for 50 min under a nitrogen atmosphere to obtain a core-shell structure aerogel.

[0030] Among them, the preparation method of the carboxymethyl chitosan / PVP-grafted porous phosphorus tailings leaching material aerogel in S2 includes the following steps: S11. Add the PVP-grafted porous phosphorus tailings leaching material to a carboxymethyl chitosan solution with a mass fraction of 12 wt%, the mass fraction of the PVP-grafted porous phosphorus tailings leaching material is 6 wt% of that of carboxymethyl chitosan, and carry out ultrasonic dispersion to obtain a suspension; S12. Add a glutaraldehyde solution with a mass fraction of 20 wt% to the suspension, the volume ratio of the glutaraldehyde solution to the carboxymethyl chitosan solution is 3:40, and stir for 60 min; S13. Freeze-dry the solution at -20 °C for 50 h to obtain the carboxymethyl chitosan / PVP-grafted porous phosphorus tailings leaching material aerogel.

[0031] Among them, the preparation method of the PVP-grafted porous phosphorus tailings leaching material in S11 includes the following steps: S21. Add phosphorus tailings to a 1.0 mol / L boric acid solution, the mass ratio of phosphorus tailings to boric acid solution is 1:10, and obtain a dissolved solution A after heating, stirring and filtering; S22. Mix the dissolution solution A with a sodium hydroxide solution having a concentration of 3 mol / L. The volume ratio of the dissolution solution A to the sodium hydroxide solution is 1:7. After stirring, filtering, and ball milling, a phosphorus tailing leaching material is obtained; S23. Heat-treat the phosphorus tailing leaching material at 900 °C for 5 h. Mix the calcined phosphorus tailing leaching material and the uncalcined phosphorus tailing leaching material according to a mass ratio of 4:10 to obtain a porous phosphorus tailing leaching material; S24. Add the porous phosphorus tailing leaching material, FeCl 2 and PVP into water according to a mass ratio of 7:0.005:1. After stirring and ultrasonic dispersion, a homogeneous suspension with a mass fraction of 9 wt% is obtained; S25. Add a dilute hydrochloric acid with a concentration of 0.5 mol / L to the homogeneous suspension to adjust the pH to 4, and add hydrogen peroxide for titration; S26. Let the solution obtained in S24 stand for 5 h, then centrifuge, filter, and wash it. Subsequently, perform ball milling to obtain a PVP-grafted porous phosphorus tailing leaching material with a particle size of 20 μm.

[0032] Example 6 A method for synthesizing a water treatment material using phosphorus tailings, the method comprising the following steps: S1. Add triallyl isocyanurate to ethylenedioxyanhydride, heat and stir at 60 °C for 30 min to obtain a homogeneous solution; S2. Add methyl acrylate and a carboxymethyl chitosan / PVP-grafted porous phosphorus tailing leaching material aerogel to the homogeneous solution. The mass of the carboxymethyl chitosan / PVP-grafted porous phosphorus tailing leaching material aerogel and methyl acrylate is 2:5. After ultrasonic treatment, perform magnetic stirring; S3. Add benzoyl peroxide, divinylbenzene, ethylenedioxyanhydride, methyl acrylate, and ammonium persulfate in a molar ratio of 0.3:2:4:0.04, and react at 70 °C for 40 min under a nitrogen atmosphere to obtain a core-shell structure aerogel.

[0033] Among them, the preparation method of the carboxymethyl chitosan / PVP-grafted porous phosphorus tailing leaching material aerogel in S2 includes the following steps: S11. Add the PVP-grafted porous phosphorus tailing leaching material to a carboxymethyl chitosan solution with a mass fraction of 9 wt%. The mass fraction of the PVP-grafted porous phosphorus tailing leaching material is 6 wt% of that of the carboxymethyl chitosan, and ultrasonic dispersion is performed to obtain a suspension; S12. Add a glutaraldehyde solution with a mass fraction of 12 wt% to the suspension. The volume ratio of the glutaraldehyde solution to the carboxymethyl chitosan solution is 5:37, and stir for 60 min; S13. Freeze-dry the solution at -20 °C for 40 h to obtain a carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel.

[0034] Among them, the preparation method of the PVP grafted porous phosphorus tailing leaching material in S11 includes the following steps: S21. Add phosphorus tailings into 1.5 mol / L boric acid solution, and the mass ratio of phosphorus tailings to boric acid solution is 1:7. After heating, stirring and filtering, a dissolved solution A is obtained; S22. Mix the dissolved solution A with a 2 mol / L sodium hydroxide solution, and the volume ratio of the dissolved solution A to the sodium hydroxide solution is 2:7. After stirring, filtering and ball milling, a phosphorus tailing leaching material is obtained; S23. Heat-treat the phosphorus tailing leaching material at 1000 °C for 6 h, and mix the calcined phosphorus tailing leaching material and the uncalcined phosphorus tailing leaching material according to a mass ratio of 4:10 to obtain a porous phosphorus tailing leaching material; S24. Add the porous phosphorus tailing leaching material, FeCl 2 and PVP into water according to a mass ratio of 4:0.005:1, and obtain a homogeneous suspension with a mass fraction of 8 wt% through stirring and ultrasonic dispersion; S25. Add 0.5 mol / L dilute hydrochloric acid to the homogeneous suspension to adjust the pH to 4, and add hydrogen peroxide for titration; S26. Let the solution obtained in S24 stand for 6 h, centrifuge, filter and wash, and then perform ball milling to obtain a PVP grafted porous phosphorus tailing leaching material with a particle size of 25 μm.

[0035] Example 7 A method for synthesizing a water treatment material using phosphorus tailings, the method includes the following steps: S1. Add triallyl isocyanurate into succinic anhydride, heat and stir at 55 °C for 35 min to obtain a homogeneous solution; S2. Add methyl acrylate and carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel into the homogeneous solution, and the mass of the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel and methyl acrylate is 2:5. After ultrasonic treatment, perform magnetic stirring; S3. Add sodium persulfate, N,N-methylenebisacrylamide, the molar ratio of succinic anhydride, methyl acrylate and ammonium persulfate is 0.3:3:3:0.05, react at 80 °C for 50 min under a nitrogen atmosphere to obtain a core-shell structure aerogel.

[0036] Among them, the preparation method of the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel in S2 includes the following steps: S11. Add the PVP-grafted porous phosphorus tailing leaching material to a 12 wt% carboxymethyl chitosan solution. The mass fraction of the PVP-grafted porous phosphorus tailing leaching material is 8 wt% of that of the carboxymethyl chitosan, and ultrasonic dispersion is carried out to obtain a suspension; S12. Add a 15 wt% glutaraldehyde solution to the suspension. The volume ratio of the glutaraldehyde solution to the carboxymethyl chitosan solution is 6:40, and stir for 60 min; S13. Freeze-dry the solution at -20 °C for 50 h to obtain a carboxymethyl chitosan / PVP-grafted porous phosphorus tailing leaching material aerogel.

[0037] Among them, the preparation method of the PVP-grafted porous phosphorus tailing leaching material in S11 includes the following steps: S21. Add phosphorus tailings to a 1.2 mol / L boric acid solution. The mass ratio of the phosphorus tailings to the boric acid solution is 1:9. After heating, stirring and filtering, a dissolved solution A is obtained; S22. Mix the dissolved solution A with a 3 mol / L sodium hydroxide solution. The volume ratio of the dissolved solution A to the sodium hydroxide solution is 1:7. After stirring, filtering and ball milling, a phosphorus tailing leaching material is obtained; S23. Heat-treat the phosphorus tailing leaching material at 1000 °C for 6 h, and mix the calcined phosphorus tailing leaching material and the uncalcined phosphorus tailing leaching material according to a mass ratio of 4:10 to obtain a porous phosphorus tailing leaching material; S24. Add the porous phosphorus tailing leaching material, FeCl 2 and PVP to water according to a mass ratio of 4:0.005:1. After stirring and ultrasonic dispersion, a homogeneous suspension with a mass fraction of 8 wt% is obtained; S25. Add a 0.5 mol / L dilute hydrochloric acid to the homogeneous suspension to adjust the pH to 4, and add hydrogen peroxide for titration; S26. Let the solution obtained in S24 stand for 4 h, centrifuge, filter and wash, and then carry out ball milling to obtain a PVP-grafted porous phosphorus tailing leaching material with a particle size of 25 μm.

[0038] Example 8 A method for synthesizing a water treatment material using phosphorus tailings, the method includes the following steps: S1. Add triallyl isocyanurate to acetic anhydride, heat and stir at 60 °C for 40 min to obtain a homogeneous solution; S2. Add methyl acrylate and carboxymethyl chitosan / PVP-grafted porous phosphorus tailing leaching material aerogel to the homogeneous solution. The mass of the carboxymethyl chitosan / PVP-grafted porous phosphorus tailing leaching material aerogel and methyl acrylate is 3:5. After ultrasonic treatment, magnetic stirring is carried out; S3. Sodium persulfate, N,N-methylenebisacrylamide, oxalic anhydride, and methyl acrylate are added in a molar ratio of 0.4:2:4:0.03, and reacted at 65 °C for 40 min under a nitrogen atmosphere to obtain a core-shell structured aerogel.

[0039] Among them, the preparation method of the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel in S2 includes the following steps: S11. Add the PVP grafted porous phosphorus tailing leaching material to a 13 wt% carboxymethyl chitosan solution, where the mass fraction of the PVP grafted porous phosphorus tailing leaching material is 10 wt% of the carboxymethyl chitosan, and ultrasonically disperse to obtain a suspension; S12. Add a 12 wt% glutaraldehyde solution to the suspension, with a volume ratio of the glutaraldehyde solution to the carboxymethyl chitosan solution of 6:40, and stir for 60 min; S13. Freeze-dry the solution at -20 °C for 40 h to obtain the carboxymethyl chitosan / PVP grafted porous phosphorus tailing leaching material aerogel.

[0040] Among them, the preparation method of the PVP grafted porous phosphorus tailing leaching material in S11 includes the following steps: S21. Add phosphorus tailings to a 0.8 mol / L boric acid solution, with a mass ratio of phosphorus tailings to boric acid solution of 1:10, and obtain a dissolved solution A after heating, stirring, and filtering; S22. Mix the dissolved solution A with a 3 mol / L sodium hydroxide solution, with a volume ratio of the dissolved solution A to the sodium hydroxide solution of 2:9, and obtain the phosphorus tailing leaching material after stirring, filtering, and ball milling; S23. Heat-treat the phosphorus tailing leaching material at 850 °C for 6 h, and mix the calcined phosphorus tailing leaching material with the uncalcined phosphorus tailing leaching material in a mass ratio of 4:10 to obtain the porous phosphorus tailing leaching material; S24. Add the porous phosphorus tailing leaching material, FeCl 2 and PVP to water in a mass ratio of 6:0.005:3, and obtain a 6 wt% homogeneous suspension after stirring and ultrasonic dispersion; S25. Add a 0.5 mol / L dilute hydrochloric acid to the homogeneous suspension to adjust the pH to 4, and add hydrogen peroxide for titration; S26. Let the solution obtained in S24 stand for 6 h, centrifuge, filter, and wash, and then perform ball milling to obtain the PVP grafted porous phosphorus tailing leaching material with a particle size of 25 μm.

[0041] Comparative Example 1 The difference between this comparative example and Example 8 is that the phosphorus tailing leaching material was not grafted and modified.

[0042] Comparative Example 2 The difference between this comparative example and Example 8 is that the phosphorus tailings leaching material was not calcined at high temperature.

[0043] Comparative Example 3 The difference between this comparative example and Example 8 is that only the calcined phosphorus tailings leaching material was used.

[0044] Comparative Example 4 The difference between this comparative example and Example 8 is that PVP-grafted porous phosphorus tailings leaching material was not added when preparing the aerogel.

[0045] Comparative Example 5 The difference between this comparative example and Example 8 is that a two-dimensional network formed by copolymerization was not prepared on the surface of the aerogel.

[0046] Performance Test Table 1 Adsorption Capability of Adsorbents for Different Dyes

[0047] Table 2 Reusability of Adsorption Capability of Adsorbents for MB Dye

[0048] Note: The adsorption recovery rate of the adsorbent in Table 2 = (last adsorption amount / initial adsorption amount) × 100% Obviously, the above-mentioned examples are only illustrations for clear explanation, and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A method for synthesizing water treatment materials using phosphate tailings, characterized in that: The water treatment material has a core-shell structure, wherein the core layer is carboxymethyl chitosan aerogel, and the shell layer is a two-dimensional network generated by copolymerization of oxalic anhydride and methyl acrylate. The carboxymethyl chitosan aerogel is coated with a PVP-grafted porous phosphorus tailings leaching material.

2. The method for synthesizing water treatment materials using phosphate tailings according to claim 1, characterized in that: The method comprises the following steps: S1. Add the crosslinking agent to oxalic anhydride, heat and stir at 40-60°C for 20-40 minutes to obtain a homogeneous solution; S2. adding methyl acrylate and carboxymethyl chitosan / PVP grafted porous phosphate tailings leaching material aerogel into the homogenous solution, and then subjecting to magnetic stirring after ultrasonication; S3. Add an initiator and react at 60-80°C for 30-50 minutes under a nitrogen atmosphere to obtain a core-shell structure aerogel.

3. The method for synthesizing water treatment materials using phosphate tailings according to claim 2, characterized in that: The cross-linking agent is one or more of N,N-methylenebisacrylamide, divinylbenzene and triallyl isocyanurate, the initiator is one or more of ammonium persulfate, sodium persulfate and dibenzoyl peroxide, the molar ratio of the cross-linking agent, oxalic anhydride, methyl propionate and initiator is 0.2-0.4:1-3:1-4:0.02-0.05, and the mass of the carboxymethyl chitosan / PVP grafted porous phosphate tailings leaching material aerogel and methyl acrylate is 1-3:2-5.

4. The method for synthesizing water treatment materials using phosphate tailings according to claim 2, characterized in that: The method for preparing the carboxymethyl chitosan / PVP grafted porous phosphate tailings leaching material aerogel in S2 comprises the following steps: S11. The PVP-grafted porous phosphate tailings leaching material was added to a 5-15wt% carboxymethyl chitosan solution and ultrasonically dispersed to obtain a suspension; S12. A 10-20wt% glutaraldehyde solution was added to the suspension and stirred for 30-60 min; S13. Freeze-dry the solution at -30 to -20°C for 30 to 50 hours to obtain a carboxymethyl chitosan / PVP grafted porous phosphate tailings leaching material aerogel.

5. The method for synthesizing water treatment materials using phosphate tailings according to claim 3, characterized in that: The mass fraction of the PVP grafted porous phosphate tailings leaching material is 5-10wt% of the carboxymethyl chitosan, and the volume ratio of the glutaraldehyde solution to the carboxymethyl chitosan solution is 2-6:25-40.

6. The method for synthesizing water treatment materials using phosphate tailings according to claim 4, characterized in that: The preparation method of the PVP grafted porous phosphate tailings leaching material in S11 comprises the following steps: S21. The phosphate tailings are added to an acidic solvent, and a solution A is obtained after heating, stirring and filtering; S22. The solution A is mixed with an alkaline solution, and the mixture is stirred, filtered and ball-milled to obtain a phosphate tailings leaching material; S23. The phosphate tailings leaching material is heated at 800-1000° C. for 4-6 hours, and the calcined phosphate tailings leaching material is mixed with the uncalcined phosphate tailings leaching material in a mass ratio of 1-4:3-10 to obtain a porous phosphate tailings leaching material; S24. adding the porous phosphate tailings leaching material, FeCl2 and PVP to water in a mass ratio of 4-7:0.005-0.008:1-3, and obtaining a homogeneous suspension by stirring and ultrasonic dispersion; S25. Add 0.1-0.5 mol / L dilute hydrochloric acid to the homogeneous suspension to adjust the pH to 2-4, and add hydrogen peroxide for titration; S26. The solution obtained in S24 is allowed to stand for 3 to 6 hours and centrifuged, filtered and washed, and then ball-milled to obtain a PVP-grafted porous phosphate tailings leaching material with a particle size of 10 to 25 μm.

7. The method for synthesizing water treatment materials using phosphate tailings according to claim 6, characterized in that: The acidic dissolving agent in S21 is one or more of boric acid, citric acid, oxalic acid, acetic acid and hydrochloric acid, the concentration of the acidic dissolving agent is 0.5-1.5 mol / L, and the mass ratio of the phosphate tailings to the acidic dissolving agent is 1:5-10.

8. The method for synthesizing water treatment materials using phosphate tailings according to claim 6, characterized in that: The alkaline solvent in S22 is one or more of sodium hydroxide, potassium hydroxide, ammonia water and sodium bicarbonate, the concentration of the alkaline solvent is 1.5-3 mol / L, and the volume ratio of the dissolving solution A to the alkaline solution is 1-3:4-10.

9. The method for synthesizing water treatment materials using phosphate tailings according to claim 6, characterized in that: The mass fraction of the homogeneous suspension in S24 is 2-8wt%.

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