A photovoltaic wastewater treatment agent and its preparation method

Abstract

The present application relates to wastewater treatment agent technical field, disclose a kind of photovoltaic wastewater treatment agent and its preparation method, the preparation method of treatment agent is as follows: aluminum salt and cerium salt are dispersed in deionized water, then surface active agent is added, and precursor is obtained after mixing uniformly;Sodium hydroxide is added in precursor to adjust pH to 7.5-8.5, after aging, centrifugal, washing, drying and calcining, modified alumina is obtained;Modified alumina is ultrasonically dispersed in deionized water, then iron salt, zirconium salt and lanthanum salt are sequentially added, and after mixing uniformly, hydrothermal reaction is carried out, and the product is cooled, centrifuged, washed and dried to obtain photovoltaic wastewater treatment agent.The wastewater treatment agent of the present application has excellent defluorination performance and can be used for purification of photovoltaic wastewater.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment agent technology, and in particular to a photovoltaic wastewater treatment agent and its preparation method. Background Technology

[0002] The manufacturing processes of photovoltaic modules, such as cleaning, etching, and electroplating, generate complex wastewater containing high concentrations of fluoride, heavy metals, and organic complexes. This type of wastewater is characterized by its complex composition, large pH fluctuations, high toxicity, and poor biodegradability. If discharged directly without effective treatment, it will pose a serious threat to the ecological environment and water safety.

[0003] Current research on fluoride-containing water treatment is extensive, with methods varying depending on the composition and content of the fluoride. These methods primarily include adsorption, chemical precipitation, and biodegradation. While these methods achieve certain water treatment effects, they also have their limitations. Precipitation-based fluoride removal is suitable for treating water with high fluoride concentrations, but it requires a high pH level, generates large amounts of toxic sludge, and often has a low removal rate. Traditional adsorption methods, especially activated alumina, offer good results, but the high cost of adsorbent regeneration limits its application in high-fluoride water treatment. There are various methods for treating fluoride-containing water, broadly categorized domestically and internationally as precipitation and adsorption. Besides these two, other methods include freezing, ion exchange resin defluorination, activated carbon defluorination, ultrafiltration, and electrodialysis, but these are rarely widely adopted due to their high cost and low defluorination rates.

[0004] Precipitation methods commonly include chemical precipitation and flocculation precipitation. Chemical precipitation is mainly used for treating high-concentration fluoride wastewater, with calcium salt precipitation (also known as lime precipitation) being a frequently employed method. This involves adding calcium salts or other chemicals to the wastewater, causing calcium ions to react with fluoride ions to form CaF₂ precipitate, thus removing fluoride from the wastewater. This process is simple, convenient, and inexpensive. However, in the commonly used lime precipitation method, the calcium fluoride precipitate formed tends to coat the surface of Ca(OH)₂ particles, preventing its full utilization. Therefore, it is necessary to add an excess of CaF₂. 2+ However, the large amount of calcium salts mixed into the sludge not only increases the sludge production but also reduces the purity of the fluoride-containing sludge. Furthermore, the fluoride content in the treated wastewater reaches over 20 mg / L. Therefore, this method is not suitable for fluoride-containing sludge. - Low-grade drinking water treatment. Flocculation and sedimentation methods for wastewater treatment easily generate very fine particulate matter with low specific gravity and high viscosity. During sedimentation, it exists as a gel, making separation difficult. After the flocculant is added, due to the presence of cations (such as Al)... 3+ Hydrolysis of the water significantly lowers its pH value, making it acidic and unsuitable for drinking.

[0005] Adsorption is a popular method due to its advantages such as simple operation, low cost, and easy availability. Adsorption methods commonly use materials such as activated carbon, alumina, silica gel, and zeolite. However, traditional alumina-based adsorbents suffer from problems such as small specific surface area, poor selectivity, low mechanical strength, and limited adsorption capacity. They are particularly unstable under high salinity and strong acid / alkali conditions, leading to inconsistent treatment efficiency.

[0006] Therefore, there is an urgent need to develop a new material for photovoltaic wastewater treatment with stable structure and excellent adsorption performance to meet the actual treatment needs of high-concentration wastewater in the photovoltaic industry. Summary of the Invention

[0007] Based on the technical problems existing in the background technology, the present invention proposes a photovoltaic wastewater treatment agent and its preparation method. The wastewater treatment agent has excellent defluorination performance and can be used for the purification of photovoltaic wastewater.

[0008] The present invention proposes a method for preparing a photovoltaic wastewater treatment agent, the method steps of which are as follows:

[0009] S1: Preparation of modified alumina;

[0010] S2: Modified alumina is ultrasonically dispersed in deionized water, and then iron salt, zirconium salt and lanthanum salt are added in sequence. After mixing, a hydrothermal reaction is carried out. The product is cooled, centrifuged, washed and dried to obtain the photovoltaic wastewater treatment agent.

[0011] Preferably, the modified alumina is prepared by the following method:

[0012] S11: Disperse aluminum salt and cerium salt in deionized water, then add surfactant, mix well to obtain precursor;

[0013] S12: Sodium hydroxide is added to the precursor to adjust the pH to 7.5-8.5, and modified alumina is obtained after aging, centrifugation, washing, drying and calcination.

[0014] Preferably, the aluminum salt is one or more of aluminum nitrate and its hydrate, aluminum chloride and its hydrate, and aluminum sulfate and its hydrate.

[0015] Preferably, it is one or more of the following: cerium nitrate and its hydrate, cerium chloride and its hydrate, and cerium sulfate and its hydrate.

[0016] Preferably, the mass ratio of aluminum salt, cerium salt and surfactant is 1:0.05-0.15:0.01-0.1.

[0017] Preferably, the aging conditions are: temperature 60-70℃, time 4-8h.

[0018] Preferably, the calcination conditions are: temperature 400-600℃, time 2-4h, and heating rate 3-7℃ / min.

[0019] Preferably, the surfactant is composed of sodium maleic anhydride octadecylamide dicarboxylate and sodium itaconic acid asymmetric diester sulfonate in a mass ratio of 2:1-4.

[0020] Preferably, the mass ratio of modified alumina, iron salt, zirconium salt and lanthanum salt is 1:0.05-0.15:0.05-0.1:0.05-0.15.

[0021] Preferably, the iron salt is one or more of ferric nitrate and its hydrate, ferric chloride and its hydrate, and ferric sulfate and its hydrate.

[0022] Preferably, the zirconium salt is one or more of zirconium nitrate and its hydrate, zirconium chloride and its hydrate, and zirconium oxychloride and its hydrate.

[0023] Preferably, the lanthanum salt is one or more of lanthanum nitrate and its hydrate and lanthanum chloride and its hydrate.

[0024] Preferably, the hydrothermal reaction temperature is 140-160℃ and the time is 4-8h.

[0025] The photovoltaic wastewater treatment agent proposed in this invention is prepared by the above-described preparation method.

[0026] Beneficial technical effects of the present invention:

[0027] (1) In this invention, cerium salt is introduced into the modified alumina precursor as a doping source, which can form Ce-doped alumina material with oxygen vacancy structure during subsequent calcination. 3+ / Ce 4+ The reversible redox properties of cerium endow the material with excellent electron transfer capabilities, enhancing its complexation and exchange capacity for heavy metal ions. Simultaneously, cerium doping helps improve the crystal structure stability of alumina particles, significantly improving their resistance to corrosion and thermal stability in high acid and alkaline environments, thereby extending the service life of the adsorbent in photovoltaic wastewater treatment. Furthermore, the addition of Ce increases the density of acidic sites on the adsorbent surface, enhancing its electrostatic adsorption capacity for anions such as fluoride ions.

[0028] (2) This invention introduces a surfactant, a compound of sodium maleic anhydride-octadecylamide-dicarboxylate and sodium itaconic acid-based asymmetric diester sulfonate, into the precursor solution, which significantly improves the particle dispersibility and pore structure control capability. On the one hand, the surfactant of this invention can inhibit particle aggregation through steric hindrance and electrostatic repulsion, making the modified alumina nanoparticles more uniform in size and higher in specific surface area; on the other hand, it can form weak coordination with metal ions, inducing the material to form a more ordered and synergistic framework structure in the hydrothermal reaction, thereby improving the multi-component synergistic adsorption performance of the subsequent composite material.

[0029] (3) This invention combines modified alumina with iron salts, zirconium salts, and lanthanum salts to form a Fe-Zr-La trimetallic modified system, which can generate a variety of active sites and a synergistic network of composite oxides on the material surface. Iron mainly exists in the Fe(III) oxidation state, possessing excellent coordination ability and flocculation effect; zirconium has a high affinity for fluoride ions, and the Zr-OH functional group it introduces can significantly enhance the specific adsorption of fluoride; lanthanum, as a typical rare earth element, has the adsorption selectivity for a variety of anions, while enhancing the overall acid and alkali corrosion resistance of the material. The synergistic loading and distribution of the three on the modified alumina carrier results in diverse functional sites on the material surface, realizing multi-mechanism, highly selective synergistic removal of fluoride from photovoltaic wastewater, greatly improving the overall treatment efficiency and stability. Attached Figure Description

[0030] Figure 1 The images show SEM images of the treatment agent proposed in this invention at different ratios; where (a) is 20 μm, (b) is 10 μm, (c) is 5 μm, and (d) is 2 μm.

[0031] Figure 2 The images are SEM images of the treatment agent proposed in this invention after adsorption at different ratios; where (a) is 20 μm, (b) is 10 μm, (c) is 5 μm, and (d) is 2 μm. Detailed Implementation

[0032] The present invention will be further explained below with reference to specific embodiments.

[0033] The preparation method of sodium maleic anhydride-octadecylamine-dicarboxylate in this embodiment of the invention is as follows: 30g of maleic anhydride, 20g of octadecylamine, and 0.8g of triethylamine are dispersed in anhydrous ethanol and reacted at room temperature for 4 hours. Then, an ethanol-water solution of NaOH is added, and the reaction is carried out at 55°C for 5 hours. After the reaction, the solution is filtered and concentrated to obtain sodium maleic anhydride-octadecylamine-dicarboxylate. The specific structural formula is as follows:

[0034] The preparation method of itaconic acid-based asymmetric diester sulfonate sodium is as follows: 0.11 mol lauryl polyoxyethylene ether (AEO-7), 0.35 g p-benzenesulfonic acid, 0.12 g hydroquinone, and 0.1 mol itaconic anhydride are mixed and refluxed for 3 h to obtain intermediate product I; 0.1 mol intermediate product I, 1 g p-toluenesulfonic acid, and 0.15 mol lauric acid monoethanolamide are mixed and refluxed for 5 h to obtain intermediate product II; 0.1 mol intermediate product II, 0.12 mol sodium bisulfite aqueous solution, and hexadecyltrimethylammonium bromide (1% of the mass of intermediate product II) are mixed and refluxed for 3 h, followed by washing and vacuum distillation to obtain itaconic acid-based asymmetric diester sulfonate sodium. The specific structural formula is as follows:

[0035] .

[0036] Example 1

[0037] Al(NO3)3·9H2O and Ce(NO3)3·6H2O were dispersed in deionized water, and then a surfactant was added and mixed to obtain a precursor. Sodium hydroxide was added to the precursor to adjust the pH to 8, and after aging, centrifugation, washing, drying and calcination, modified alumina was obtained.

[0038] Modified alumina was ultrasonically dispersed in deionized water, and then FeCl3·6H2O, ZrOCl2·8H2O and La(NO3)3·6H2O were added in sequence. After mixing, a hydrothermal reaction was carried out. The product was cooled, centrifuged, washed and dried to obtain the photovoltaic wastewater treatment agent.

[0039] The mass ratio of Al(NO3)3·9H2O, Ce(NO3)3·6H2O and surfactant was 1:0.1:0.05; the aging conditions were: temperature 65℃, time 6h; the calcination conditions were: temperature 500℃, time 3h, heating rate 5℃ / min.

[0040] The surfactant is composed of sodium maleic anhydride-octadecylamide-dicarboxylate and sodium itaconic acid-based asymmetric diester sulfonate in a 1:1 mass ratio.

[0041] The mass ratio of modified alumina, FeCl3·6H2O, ZrOCl2·8H2O and La(NO3)3·6H2O was 1:0.1:0.08:0.1; the hydrothermal reaction was carried out at 150℃ for 6 hours.

[0042] Figure 1 The images show SEM images of the treatment agent prepared in this embodiment at different magnifications. The treatment agent has a core-shell structure and produces a large number of large pores, resulting in a significant increase in specific surface area. This provides more adsorption sites for fluoride ions, which is beneficial for the removal of fluoride from water.

[0043] Figure 2 The images are SEM images of the treatment agent proposed in this invention after adsorption at different magnifications. The surface of the reacted material is coated with a layer of substance and adsorbs a large number of fine particles. The pores are filled by these particles, forming a complex. The surface is smoother than the material before the reaction, and the structure of the complex is more compact. It is speculated that its defluorination mechanism includes surface adsorption-complexation. Example 2

[0044] Al(NO3)3·9H2O and Ce(NO3)3·6H2O were dispersed in deionized water, and then a surfactant was added and mixed to obtain a precursor. Sodium hydroxide was added to the precursor to adjust the pH to 7.5. After aging, centrifugation, washing, drying and calcination, modified alumina was obtained.

[0045] Modified alumina was ultrasonically dispersed in deionized water, and then FeCl3·6H2O, ZrOCl2·8H2O and La(NO3)3·6H2O were added in sequence. After mixing, a hydrothermal reaction was carried out. The product was cooled, centrifuged, washed and dried to obtain the photovoltaic wastewater treatment agent.

[0046] The mass ratio of Al(NO3)3·9H2O, Ce(NO3)3·6H2O and surfactant was 1:0.05:0.01; the aging conditions were: temperature 60℃, time 8h; the calcination conditions were: temperature 400℃, time 4h, heating rate 3℃ / min.

[0047] The surfactant is composed of sodium maleic anhydride-octadecylamide-dicarboxylate and sodium itaconic acid-based asymmetric diester sulfonate in a 2:1 mass ratio.

[0048] The mass ratio of modified alumina, FeCl3·6H2O, ZrOCl2·8H2O and La(NO3)3·6H2O was 1:0.05:0.05:0.05; the hydrothermal reaction was carried out at 140℃ for 8 hours. Example 3

[0049] Al(NO3)3·9H2O and Ce(NO3)3·6H2O were dispersed in deionized water, and then a surfactant was added and mixed to obtain a precursor. Sodium hydroxide was added to the precursor to adjust the pH to 8.5, and after aging, centrifugation, washing, drying and calcination, modified alumina was obtained.

[0050] Modified alumina was ultrasonically dispersed in deionized water, and then FeCl3·6H2O, ZrOCl2·8H2O and La(NO3)3·6H2O were added in sequence. After mixing, a hydrothermal reaction was carried out. The product was cooled, centrifuged, washed and dried to obtain the photovoltaic wastewater treatment agent.

[0051] The mass ratio of Al(NO3)3·9H2O, Ce(NO3)3·6H2O and surfactant was 1:0.15:0.1; the aging conditions were: temperature 70℃, time 4h; the calcination conditions were: temperature 600℃, time 2h, heating rate 7℃ / min.

[0052] The surfactant is composed of sodium maleic anhydride-octadecylamide-dicarboxylate and sodium itaconic acid-based asymmetric diester sulfonate in a mass ratio of 1:2.

[0053] The mass ratio of modified alumina, FeCl3·6H2O, ZrOCl2·8H2O and La(NO3)3·6H2O was 1:0.15:0.1:0.15; the hydrothermal reaction was carried out at 160℃ for 4 hours. Comparative Example 1

[0054] Al(NO3)3·9H2O was dispersed in deionized water, and then a surfactant was added and mixed to obtain a precursor. Sodium hydroxide was added to the precursor to adjust the pH to 8, and after aging, centrifugation, washing, drying and calcination, modified alumina was obtained.

[0055] Modified alumina was ultrasonically dispersed in deionized water, and then FeCl3·6H2O, ZrOCl2·8H2O and La(NO3)3·6H2O were added in sequence. After mixing, a hydrothermal reaction was carried out. The product was cooled, centrifuged, washed and dried to obtain the photovoltaic wastewater treatment agent.

[0056] The mass ratio of Al(NO3)3·9H2O to surfactant was 1:0.05; the aging conditions were: temperature 65℃, time 6h; the calcination conditions were: temperature 500℃, time 3h, heating rate 5℃ / min.

[0057] The surfactant is composed of sodium maleic anhydride-octadecylamide-dicarboxylate and sodium itaconic acid-based asymmetric diester sulfonate in a 1:1 mass ratio.

[0058] The mass ratio of modified alumina, FeCl3·6H2O, ZrOCl2·8H2O and La(NO3)3·6H2O was 1:0.1:0.08:0.1; the hydrothermal reaction was carried out at 150℃ for 6 hours. Comparative Example 2

[0059] Al(NO3)3·9H2O and Ce(NO3)3·6H2O were dispersed in deionized water, and then a surfactant was added and mixed to obtain a precursor. Sodium hydroxide was added to the precursor to adjust the pH to 8, and after aging, centrifugation, washing, drying and calcination, modified alumina was obtained.

[0060] Modified alumina was ultrasonically dispersed in deionized water, and then FeCl3·6H2O, ZrOCl2·8H2O and La(NO3)3·6H2O were added in sequence. After mixing, a hydrothermal reaction was carried out. The product was cooled, centrifuged, washed and dried to obtain the photovoltaic wastewater treatment agent.

[0061] The mass ratio of Al(NO3)3·9H2O, Ce(NO3)3·6H2O and surfactant was 1:0.1:0.05; the aging conditions were: temperature 65℃, time 6h; the calcination conditions were: temperature 500℃, time 3h, heating rate 5℃ / min.

[0062] The surfactant is sodium maleic anhydride octadecylamide dicarboxylate.

[0063] The mass ratio of modified alumina, FeCl3·6H2O, ZrOCl2·8H2O and La(NO3)3·6H2O was 1:0.1:0.08:0.1; the hydrothermal reaction was carried out at 150℃ for 6 hours. Comparative Example 3

[0064] Al(NO3)3·9H2O and Ce(NO3)3·6H2O were dispersed in deionized water, and then a surfactant was added and mixed to obtain a precursor. Sodium hydroxide was added to the precursor to adjust the pH to 8, and after aging, centrifugation, washing, drying and calcination, modified alumina was obtained.

[0065] Modified alumina was ultrasonically dispersed in deionized water, and then FeCl3·6H2O, ZrOCl2·8H2O and La(NO3)3·6H2O were added in sequence. After mixing, a hydrothermal reaction was carried out. The product was cooled, centrifuged, washed and dried to obtain the photovoltaic wastewater treatment agent.

[0066] The mass ratio of Al(NO3)3·9H2O, Ce(NO3)3·6H2O and surfactant was 1:0.1:0.05; the aging conditions were: temperature 65℃, time 6h; the calcination conditions were: temperature 500℃, time 3h, heating rate 5℃ / min.

[0067] The surfactant is sodium itaconic acid-based asymmetric diester sulfonate.

[0068] The mass ratio of modified alumina, FeCl3·6H2O, ZrOCl2·8H2O and La(NO3)3·6H2O was 1:0.1:0.08:0.1; the hydrothermal reaction was carried out at 150℃ for 6 hours. Comparative Example 4

[0069] Al(NO3)3·9H2O and Ce(NO3)3·6H2O were dispersed in deionized water, and then a surfactant was added and mixed to obtain a precursor. Sodium hydroxide was added to the precursor to adjust the pH to 8, and after aging, centrifugation, washing, drying and calcination, modified alumina was obtained.

[0070] Modified alumina was ultrasonically dispersed in deionized water, and then ZrOCl2·8H2O and La(NO3)3·6H2O were added sequentially. After mixing, a hydrothermal reaction was carried out. The product was cooled, centrifuged, washed and dried to obtain the photovoltaic wastewater treatment agent.

[0071] The mass ratio of Al(NO3)3·9H2O, Ce(NO3)3·6H2O and surfactant was 1:0.1:0.05; the aging conditions were: temperature 65℃, time 6h; the calcination conditions were: temperature 500℃, time 3h, heating rate 5℃ / min.

[0072] The surfactant is composed of sodium maleic anhydride-octadecylamide-dicarboxylate and sodium itaconic acid-based asymmetric diester sulfonate in a 1:1 mass ratio.

[0073] The mass ratio of modified alumina, ZrOCl2·8H2O and La(NO3)3·6H2O was 1:0.13:0.15; the hydrothermal reaction was carried out at 150℃ for 6 hours. Comparative Example 5

[0074] Al(NO3)3·9H2O and Ce(NO3)3·6H2O were dispersed in deionized water, and then a surfactant was added and mixed to obtain a precursor. Sodium hydroxide was added to the precursor to adjust the pH to 8, and after aging, centrifugation, washing, drying and calcination, modified alumina was obtained.

[0075] Modified alumina was ultrasonically dispersed in deionized water, and then FeCl3·6H2O and La(NO3)3·6H2O were added sequentially. After mixing, a hydrothermal reaction was carried out. The product was cooled, centrifuged, washed and dried to obtain the photovoltaic wastewater treatment agent.

[0076] The mass ratio of Al(NO3)3·9H2O, Ce(NO3)3·6H2O and surfactant was 1:0.1:0.05; the aging conditions were: temperature 65℃, time 6h; the calcination conditions were: temperature 500℃, time 3h, heating rate 5℃ / min.

[0077] The surfactant is composed of sodium maleic anhydride-octadecylamide-dicarboxylate and sodium itaconic acid-based asymmetric diester sulfonate in a 1:1 mass ratio.

[0078] The mass ratio of modified alumina, FeCl3·6H2O and La(NO3)3·6H2O was 1:0.14:0.14; the hydrothermal reaction was carried out at 150℃ for 6 hours. Comparative Example 6

[0079] Al(NO3)3·9H2O and Ce(NO3)3·6H2O were dispersed in deionized water, and then a surfactant was added and mixed to obtain a precursor. Sodium hydroxide was added to the precursor to adjust the pH to 8, and after aging, centrifugation, washing, drying and calcination, modified alumina was obtained.

[0080] Modified alumina was ultrasonically dispersed in deionized water, and then FeCl3·6H2O and ZrOCl2·8H2O were added sequentially. After mixing, a hydrothermal reaction was carried out. The product was cooled, centrifuged, washed, and dried to obtain the photovoltaic wastewater treatment agent.

[0081] The mass ratio of Al(NO3)3·9H2O, Ce(NO3)3·6H2O and surfactant was 1:0.1:0.05; the aging conditions were: temperature 65℃, time 6h; the calcination conditions were: temperature 500℃, time 3h, heating rate 5℃ / min.

[0082] The surfactant is composed of sodium maleic anhydride-octadecylamide-dicarboxylate and sodium itaconic acid-based asymmetric diester sulfonate in a 1:1 mass ratio.

[0083] The mass ratio of modified alumina, FeCl3·6H2O and ZrOCl2·8H2O was 1:0.15:0.13; the hydrothermal reaction was carried out at 150℃ for 6 hours.

[0084] The treatment agents prepared in Example 1 and Comparative Examples 1-6 were used to treat wastewater from a photovoltaic plant, and their defluorination performance was measured. The test results are shown in Table 1.

[0085] The test method is as follows: the treatment agent is made into a filter column, and then wastewater is introduced at a rate of 6 m / h. The pH of the wastewater is 6.5, and the fluoride concentration in the wastewater before and after the filter column is introduced is measured.

[0086] Table 1 Results of Fluoride Removal Performance Test

[0087]

[0088] As can be seen from the experimental results of Examples 1-3 in Table 1, the treatment agent of the present invention has excellent defluorination performance. The treatment agent of Example 1 can reduce the fluoride content in wastewater to 0.4 mg / L, which meets the discharge requirements.

[0089] As can be seen from the experimental results of Example 1 and Comparative Example 1, the present invention can further improve the defluorination performance of the treatment agent by doping with cerium when preparing modified alumina. This is because the introduced cerium salt, as a dopant source, can form Ce-doped alumina material with an oxygen vacancy structure during subsequent calcination. 3+ / Ce 4+The reversible redox properties of cerium endow the material with excellent electron transfer capabilities, enhancing its complexation and exchange capacity for heavy metal ions. Simultaneously, cerium doping helps improve the crystal structure stability of alumina particles, significantly improving their resistance to corrosion and thermal stability in high acid and alkaline environments, thereby extending the service life of the adsorbent in photovoltaic wastewater treatment. Furthermore, the addition of Ce increases the density of acidic sites on the adsorbent surface, enhancing its electrostatic adsorption capacity for anions such as fluoride ions.

[0090] As can be seen from the experimental results of Example 1 and Comparative Examples 2-3, the present invention, by introducing a compound of sodium maleic anhydride-octadecylamide dicarboxylate and sodium itaconic acid-based asymmetric diester sulfonate as a surfactant into the precursor solution, has a synergistic promoting effect on improving the defluorination performance of the treatment agent. This is because the surface modifier of this application significantly improves the particle dispersibility and pore structure control ability. On the one hand, the surfactant of the present invention can inhibit particle agglomeration through steric hindrance and electrostatic repulsion effects, making the modified alumina nanoparticles more uniform in size and higher in specific surface area; on the other hand, it can form weak coordination with metal ions, inducing the material to form a more ordered and synergistic framework structure in the hydrothermal reaction, thereby improving the multi-component synergistic adsorption performance of the subsequent composite material.

[0091] As can be seen from the experimental results of Example 1 and Comparative Examples 4-6, this invention, by combining modified alumina with iron salts, zirconium salts, and lanthanum salts to form a Fe-Zr-La trimetallic modified system, can generate multiple active sites and a synergistic network of composite oxides on the material surface, further improving the fluoride removal performance of the treatment agent. Iron mainly exists in the Fe(III) oxidation state, possessing excellent coordination ability and flocculation effect, effectively complexing phosphorus, arsenic, and organic complexes in wastewater. Zirconium has a high affinity for fluoride ions, and the Zr-OH functional groups it introduces can significantly enhance the specific adsorption of fluoride and phosphate. Lanthanum, as a typical rare earth element, possesses adsorption selectivity for multiple anions, while also enhancing the overall acid and alkali corrosion resistance of the material. The synergistic loading and distribution of the three elements on the modified alumina carrier results in diverse functional sites on the material surface, achieving multi-mechanism, highly selective synergistic removal of fluoride from photovoltaic wastewater, greatly improving the overall treatment efficiency and stability.

[0092] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application. The scope of this application is defined by the appended claims and their equivalents, all of which should be included within the protection scope of this application.

Claims

1. A method of preparing a photovoltaic wastewater treatment agent, characterized by, The method steps are as follows: S1: preparation of modified alumina; S2: dispersing the modified alumina in deionized water, then adding iron salt, zirconium salt and lanthanum salt in sequence, mixing uniformly, and then hydrothermally reacting, and the product is obtained after cooling, centrifuging, washing and drying, thereby obtaining the photovoltaic wastewater treatment agent; the mass ratio of the modified alumina, the iron salt, the zirconium salt and the lanthanum salt is 1:0.05-0.15:0.05-0.1:0.05-0.15; The preparation method of the modified alumina is as follows: S11: dispersing aluminum salt and cerium salt in deionized water, then adding surfactant, mixing uniformly, and obtaining the precursor; the mass ratio of the aluminum salt, the cerium salt and the surfactant is 1:0.05-0.15:0.01-0.1; S12: adding sodium hydroxide to the precursor to adjust the pH to 7.5-8.5, and then obtaining the modified alumina after aging, centrifuging, washing, drying and calcining; The surfactant is composed of maleopimaric acid octadecyl amide sodium dicarboxylate and itaconic acid-based unsymmetrical diester sodium sulfonate at a mass ratio of 2:1-4.

2. A method of preparing a photovoltaic wastewater treatment agent according to claim 1, characterized by, The aluminum salt is one or more of aluminum nitrate and its hydrate, aluminum chloride and its hydrate, and aluminum sulfate and its hydrate; The cerium salt is one or more of cerium nitrate and its hydrate, cerium chloride and its hydrate, and cerium sulfate and its hydrate.

3. The method for preparing a photovoltaic wastewater treatment agent according to claim 1, characterized in that, The aging condition is: temperature 60-70℃, time 4-8h; The calcining condition is: temperature 400-600℃, time 2-4h, and heating rate 3-7℃ / min.

4. The method for preparing a photovoltaic wastewater treatment agent according to claim 1, characterized in that, The iron salt is one or more of iron nitrate and its hydrate, iron chloride and its hydrate, and iron sulfate and its hydrate; The zirconium salt is one or more of zirconium nitrate and its hydrate, zirconium chloride and its hydrate, and zirconium oxychloride and its hydrate; The lanthanum salt is one or more of lanthanum nitrate and its hydrate, and lanthanum chloride and its hydrate.

5. The method for preparing a photovoltaic wastewater treatment agent according to claim 1, characterized in that, The hydrothermal reaction temperature is 140-160℃, and the time is 4-8h.

6. A photovoltaic wastewater treatment agent, characterized by, The preparation method is prepared by any one of claims 1-5.

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