Silane-bonded aluminosilicate-based supermolecular defluoridation coagulant, preparation method and application thereof

Abstract

The application discloses a silane-bonded aluminum-silicon-based supermolecular defluorination coagulant as well as a preparation method and application thereof, and belongs to the technical field of water treatment. The silane-bonded aluminum-silicon-based supermolecular defluorination coagulant is constructed by silane coupling to form a ≡Si-(CH2)3-NH2 supermolecular capture site, so that the hydrogen bond adsorption of fluorine ions is enhanced. The Si-O-Al grid structure is accurately controlled by a pulse gradient assembly strategy, so that efficient complexation of fluorine ions is realized. Fractional pressure immersion ensures that the Keggin structure aluminum active component is embedded, and the removal rate of low-fluorine water is significantly improved. The silane-bonded aluminum-silicon-based supermolecular defluorination coagulant can efficiently remove fluorine ions in low-concentration fluorine-containing wastewater, and is especially suitable for wastewater treatment in the photovoltaic industry.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and in particular relates to a silane-bonded aluminum-silicon-based supramolecular defluorination coagulant, its preparation method, and its application. Background Technology

[0002] Industrial fluoride-containing wastewater is characterized by its complex composition, high salinity, and difficulty in biochemical treatment. Currently, commonly used treatment methods include coagulation sedimentation, chemical precipitation, ion exchange, adsorption, and membrane separation. Among these, chemical precipitation can generally only reduce the fluoride concentration to 20–30 mg / L, making deep fluoride removal difficult. Adsorption, ion exchange, electrodialysis, and membrane separation can all achieve deep fluoride removal, but their high operating costs and complex operations limit their large-scale application. Coagulation sedimentation offers advantages such as small footprint, simple operation, low cost, and high efficiency, making it the most widely used fluoride removal process. However, traditional coagulation processes have limited effectiveness in treating low-concentration fluoride wastewater. Therefore, overcoming the bottleneck of poor fluoride ion removal efficiency in coagulation is the most economical and simple strategy for deep fluoride removal.

[0003] The type of coagulant / flocculator is a core factor affecting water treatment efficiency. Currently, aluminum salt coagulants are the most widely used in water plants. However, the molecular weight of the hydroxyl complexes formed by the hydrolysis of aluminum salts is limited, only a few hundred to a few thousand Daltons. In the treatment of low-concentration fluoride wastewater, the Al-F complexes generated cannot meet the requirements for mesoscale coagulation nuclei, making sedimentation and separation difficult, resulting in fluoride concentrations in the effluent failing to meet the 2 mg / L limit. Therefore, increasing the molecular weight of the hydrolysis products of aluminum salt coagulants is a key technology for deep fluoride removal. Polyaluminum silicate composite coagulants can achieve deep fluoride ion reduction because their hydrolysis products contain a large number of active hydroxyl groups. - It can replace OH - This forms Si-F and Al-F complexes, reducing F - The hydrophilicity of aluminum silicate facilitates its destabilization and sedimentation. Compared to trivalent aluminum, tetravalent silicon has more hydroxyl coordination sites. Unlike the two-dimensional linear structure of aluminum salt hydrolysis products, aluminum silicate hydrolysis tends to form polymers with a three-dimensional network structure. During coagulation, it can exert a stronger bridging and netting / sweeping effect. The resulting "coagulant-pollutant" complex meets the requirements of a mesoscale coagulation nucleus, which can further aggregate to produce flocs with good settling performance, ultimately achieving the separation of F- from the water. Although aluminum silicate composite coagulants possess both the stability of a silicon framework and the active sites of aluminum, they suffer from weak silicon-aluminum interfacial bonding, poor stability, and difficulties in aluminum-silicon polymerization. Summary of the Invention

[0004] To address the current technical problems of difficulty in treating low-concentration fluoride-containing wastewater and the poor and unstable performance of silicon-aluminum composite coagulants, this invention provides a silane-bonded aluminum-silicon-based supramolecular defluorination coagulant, its preparation method, and its application.

[0005] One of the technical solutions provided by this invention:

[0006] A method for preparing a silane-bonded aluminum-silicon-based supramolecular defluorination coagulant includes the following steps: mixing activated alumina and a silane coupling agent, heating and stirring under a nitrogen atmosphere to prepare a silane-functionalized alumina matrix; adding activated silicic acid to the silane-functionalized alumina matrix in batches using a pulsed gradient assembly strategy, adjusting the pH and reaction temperature of the reaction system in batches, and cooling to room temperature using a gradient cooling strategy after the reaction to complete the construction of the activated silicic acid template and prepare a silicon-aluminum composite mixture; injecting aluminum sulfate solution into the silicon-aluminum composite mixture in three batches under ice bath conditions, and simultaneously performing an impregnation reaction in three batches to complete the loading of aluminum sulfate active sites and prepare the silane-bonded aluminum-silicon-based supramolecular defluorination coagulant.

[0007] This invention breaks through the bottleneck of silane coupling interface recombination and multi-level structure precise control, slows down the chain reaction of silicon and aluminum interface hydrolysis, innovates the pulse gradient assembly strategy to control the molecular-level epitaxial growth of silicon and aluminum hydrolysis products, and introduces activated alumina to solve the bottleneck problem of difficulty in forming coagulation nuclei in the coagulation process of low-concentration fluoride wastewater, providing a revolutionary solution for the deep defluorination of drinking water.

[0008] The steps of the pulsed gradient assembly strategy in this invention are as follows: First, add 40% activated silica to the silane-functionalized alumina matrix, adjust the pH to 5.0, heat to 30°C, and stir at 600 rpm for 10 min. Then, add 30% activated silica, adjust the pH to 5.0, heat to 40°C, and stir at 500 rpm for 10 min. Finally, add the remaining 30% activated silica, adjust the pH to 5.0, heat to 50°C, and slowly ripen at 300 rpm for 20 min.

[0009] The gradient cooling strategy in this invention is as follows: after the reaction is completed, the temperature is reduced at 10°C intervals, and each temperature gradient is maintained for 15 minutes until the temperature drops to room temperature.

[0010] The specific reaction process of the silicon-aluminum composite mixture and aluminum sulfate solution in this invention is as follows: the silicon-aluminum composite mixture is placed under ice bath conditions, and aluminum sulfate solution (25wt%) is injected in three parts. The three-part injection method is as follows: the first injection is 50%, and the solution is immersed in vacuum negative pressure (-0.08MPa) for 20 minutes; the second injection is 30%, and the solution is immersed in normal pressure for 10 minutes; the third injection is 20%, and the solution is immersed in vacuum negative pressure for 15 minutes.

[0011] Furthermore, the weight ratio of the activated alumina to the silane coupling agent is 1:(0.2-0.5).

[0012] Furthermore, the weight ratio of the activated alumina to the silane coupling agent is 1:0.3.

[0013] Furthermore, the temperature of the heating and stirring reaction is 50-70°C.

[0014] Furthermore, the temperature of the heating and stirring reaction is 50°C.

[0015] Furthermore, the weight ratio of the silane-functionalized alumina matrix to the activated silica is 1:0.3.

[0016] Furthermore, the volume ratio of the silicon-aluminum composite mixture to the aluminum sulfate solution is 1:(1-2.5), and the concentration of the aluminum sulfate solution is 25 wt.%.

[0017] Furthermore, the volume ratio of the silicon-aluminum composite mixture to the aluminum sulfate solution is 1:1.

[0018] The second technical solution provided by this invention:

[0019] A silane-bonded aluminum-silicon-based supramolecular defluorination coagulant prepared by the above preparation method.

[0020] The third technical solution provided by this invention:

[0021] Application of the above-mentioned silane-bonded aluminum-silicon-based supramolecular defluorinating coagulant in the treatment of photovoltaic wastewater.

[0022] Compared with the prior art, the present invention has the following advantages and technical effects:

[0023] The silane-bonded aluminum-silicon-based supramolecular defluoridation coagulant provided by this invention constructs ≡Si-(CH2)3-NH2 supramolecular trapping sites through silane coupling, enhancing the hydrogen bond adsorption of fluoride ions; it precisely controls the Si-O-Al network structure through a pulse gradient assembly strategy to achieve efficient fluoride ion complexation; and it ensures the embedding of the Keggin structure aluminum active component through staged pressure-switching impregnation, significantly improving the removal rate of low-fluoride water. The silane-bonded aluminum-silicon-based supramolecular defluoridation coagulant provided by this invention can efficiently remove fluoride ions from low-concentration fluoride-containing wastewater, and is particularly suitable for wastewater treatment in the photovoltaic industry. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 (a) is a TEM image of activated alumina, and (b) is a TEM image of the silane-bonded aluminum-silicon-based supramolecular defluorination coagulant prepared in this example (i.e., Example 8).

[0026] Figure 2 This is a comparison diagram of the coagulation process of the silane-bonded aluminum-silicon-based supramolecular defluorination coagulant prepared in this embodiment (i.e., Example 8) and commercially available aluminum sulfate. Detailed Implementation

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0028] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0029] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0030] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This specification and embodiments are merely exemplary.

[0031] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0032] The room temperature in this invention refers to 25±2℃.

[0033] In this embodiment of the invention, the silane coupling agent selected is KH-550 silane coupling agent, namely 3-aminopropyltriethoxysilane.

[0034] In the embodiments of this invention, the activated alumina, 3-aminopropyltriethoxysilane, activated silicic acid, and aluminum sulfate were all purchased commercially.

[0035] In this embodiment of the invention, the photovoltaic wastewater is actual wastewater from a photovoltaic factory in Shandong Province. Photovoltaic wastewater is characterized by its complex composition, high salinity, and difficulty in biochemical treatment, making it challenging to treat.

[0036] Example 1

[0037] S1. Preparation of silane-functionalized alumina matrix: Weigh 100 parts by mass of 5 groups of active alumina (particle size 150 mesh), and place them in a vacuum drying oven at 105℃ for 2 hours to dehydrate; after cooling to 50℃, transfer them to a three-necked flask under nitrogen protection; then add 3-aminopropyltriethoxysilane, wherein the weight ratio of active alumina to 3-aminopropyltriethoxysilane is 1:0.1, 1:0.2, 1:0.3, 1:0.4 and 1:0.5 respectively; maintain the reaction temperature at 50℃, stir at 300 rpm for 2 hours, and then perform vacuum filtration, ethanol washing and vacuum drying to prepare silane-functionalized alumina matrix;

[0038] S2. Construction of activated silica template: Weigh 100 parts of silane-functionalized alumina matrix prepared in S1. Using a pulsed gradient assembly strategy, activated silica was added in batches. The pulsed gradient assembly strategy steps are as follows: First, add 40% activated silica, adjust the pH to 5.0, heat to 30℃, and stir at 600 rpm for 10 min. Then, add 30% activated silica, adjust the pH to 5.0, heat to 40℃, and stir at 500 rpm for 10 min. Finally, add the remaining 30% activated silica, adjust the pH to 5.0, heat to 50℃, and slowly mature at 300 rpm for 20 min. The weight ratio of silane-functionalized alumina matrix to total activated silica is 1:0.4. The pH of the system was adjusted using 0.5M sulfuric acid solution and 0.5M sodium hydroxide solution. After the reaction was completed, a gradient cooling strategy was used (10℃ intervals, each temperature gradient maintained for 15 min) to cool to room temperature, obtaining a silica-alumina composite mixture, thus completing the construction of the activated silica template.

[0039] S3. Loading of active sites on aluminum sulfate: 20 mL of the silicon-aluminum composite mixture prepared in S3 was placed in an ice bath. Aluminum sulfate solution (25 wt%) was injected in three portions. The first portion was 50%, and the mixture was immersed under vacuum pressure (-0.08 MPa) for 20 min. The second portion was 30%, and the mixture was immersed under normal pressure for 10 min. The third portion was 20%, and the mixture was immersed under vacuum pressure for 15 min. The total volume ratio of the silicon-aluminum composite mixture to the aluminum sulfate solution was 1:1. This prepared a silane-bonded aluminum-silicon-based supramolecular defluorination coagulant.

[0040] The above-mentioned silane-bonded aluminum-silicon-based supramolecular defluorination coagulant was used to treat photovoltaic wastewater with a fluoride ion concentration of 12.5–19.8 mg / L and a defluorination coagulant dosage of 25 mg / L. Table 1 shows the electrical properties and defluorination rate of the defluorination coagulants prepared with different weight ratios of active alumina and 3-aminopropyltriethoxysilane.

[0041] The method for determining the electrical properties is as follows: prepare a 1.0 g / L coagulant solution, use a zetasizer nano series potentiometric particle size analyzer to measure the electrical properties of the coagulant, and take the average value of three test results as the zeta potential of the coagulant.

[0042]

[0043] Table 1

[0044]

[0045] Note: The weight ratios in Table 1 are the weight ratios of activated alumina to 3-aminopropyltriethoxysilane.

[0046] Example 2

[0047] Based on Example 1, the weight ratio of activated alumina to 3-aminopropyltriethoxysilane was selected as 1:0.3. Then, the reaction temperatures in the preparation of the silane-functionalized alumina matrix were adjusted to 30℃, 40℃, 50℃, 60℃, and 70℃. The treatment effects of the five different defluorination coagulants on photovoltaic wastewater were compared. The test methods were the same as in Example 1. Table 2 shows the results of the determination of the electrical properties and defluorination efficiency of the defluorination coagulants at different reaction temperatures.

[0048] Table 2

[0049]

[0050] Example 3

[0051] Based on Examples 1 and 2, the weight ratio of activated alumina to 3-aminopropyltriethoxysilane was selected as 1:0.3, the reaction temperature was 50°C, and the method of adding activated silica was adjusted to compare the one-time assembly strategy and the pulsed gradient assembly strategy.

[0052] The steps for constructing the activated silica template using a one-step assembly strategy are as follows: Weigh 100 parts of silane-functionalized alumina matrix, add all the activated silica to the silane-functionalized alumina matrix at once, adjust the pH to 5.0, heat to 50℃, and stir at 600 rpm for 30 min. The weight ratio of silane-functionalized alumina matrix to activated silica is 1:0.3. Adjust the pH of the system using 0.5M sulfuric acid solution and 0.5M sodium hydroxide solution. After the reaction is complete, use a gradient cooling strategy (10℃ interval, each temperature gradient is maintained for 15 min) to cool to room temperature to obtain a silica-alumina composite mixture, thus completing the construction of the activated silica template.

[0053] The treatment effects of two different defluoridation coagulants on photovoltaic wastewater were compared. Table 3 shows the results of the determination of the electrical properties and defluoridation efficiency of the defluoridation coagulants prepared by different activated silica addition methods.

[0054] Table 3

[0055]

[0056] Example 4

[0057] Based on Examples 1-3, the weight ratio of activated alumina to 3-aminopropyltriethoxysilane was selected as 1:0.3, the reaction temperature was 50℃, and a pulsed dosing strategy was adopted for the activation of silicic acid. Then, the weight ratio of silane-functionalized alumina matrix to activated silicic acid was adjusted to 1:(0.1-0.5). The treatment effects of five different defluorination coagulants on photovoltaic wastewater were compared. Table 4 shows the results of the determination of the electrical properties and defluorination rate of the defluorination coagulants under different weight ratios of silane-functionalized alumina matrix to activated silicic acid.

[0058] Table 4

[0059]

[0060] As can be seen from Table 4, although the less activated silica, the higher the defluorination rate, the poorer the floc characteristics and the poorer the sedimentation performance. Starting from 1:0.3, the floc sedimentation performance improved. Therefore, considering both the defluorination rate and the solid-liquid separation efficiency, the weight ratio of silane-functionalized alumina matrix to activated silica was determined to be 1:0.3.

[0061] Example 5

[0062] Based on Examples 1-4, the weight ratio of activated alumina to 3-aminopropyltriethoxysilane was selected as 1:0.3, the reaction temperature was 50℃, the activated silicic acid was added using a pulse dosing strategy, and the weight ratio of silane-functionalized alumina matrix to activated silicic acid was 1:0.3. Then, the cooling method in the loading of aluminum sulfate active sites was adjusted, and either a one-step cooling method or a gradient cooling strategy was selected. Table 5 shows the results of the determination of the electrical properties and defluorination efficiency of the defluorination coagulants prepared by different cooling strategies.

[0063] Table 5

[0064]

[0065] Example 6

[0066] Based on Examples 1-5, the weight ratio of activated alumina to 3-aminopropyltriethoxysilane was selected as 1:0.3, the reaction temperature was 50°C, the activated silicic acid was activated using a pulsed dosing strategy, the weight ratio of silane-functionalized alumina matrix to activated silicic acid was 1:0.3, a gradient cooling strategy was adopted, and then the injection method of aluminum sulfate solution in the aluminum sulfate active site loading was adjusted, which was divided into single injection and three injections.

[0067] The specific operation process for the one-time injection is as follows: under ice bath conditions, a predetermined volume of aluminum sulfate solution is injected into the silicon-aluminum composite mixture.

[0068] Table 6 shows the electrical properties and defluorination efficiency of defluorinating coagulants prepared by different injection methods of aluminum sulfate.

[0069] Table 6

[0070]

[0071] As can be seen from Table 6, a one-time injection of aluminum sulfate will result in excessive hydrolysis on the surface, which, although highly electrical, has poor effect.

[0072] Example 7

[0073] Based on Examples 1-6, the weight ratio of activated alumina to 3-aminopropyltriethoxysilane was selected as 1:0.3, the reaction temperature was 50℃, the activated silicic acid was added using a pulse dosing strategy, the weight ratio of silane-functionalized alumina matrix to activated silicic acid was 1:0.3, a gradient cooling strategy was adopted, and the aluminum sulfate solution was injected in three parts. Then the volume ratio of the silicon-aluminum composite mixture to aluminum sulfate was adjusted to 1:(0.5-2.5). Table 7 shows the results of the determination of the electrical properties and defluorination efficiency of the coagulant under different volume ratios of silicon-aluminum composite mixture to aluminum sulfate.

[0074] Table 7

[0075]

[0076] Example 8

[0077] Based on Examples 1-7, the preparation method of the silane-bonded aluminum-silicon-based supramolecular defluorination coagulant is as follows:

[0078] S1. Preparation of silane-functionalized alumina matrix: Weigh 100 parts of activated alumina (particle size 150 mesh) and place it in a vacuum drying oven at 105℃ for 2 hours to dehydrate; after cooling to 50℃, transfer it to a three-necked flask under nitrogen protection; add 3-aminopropyltriethoxysilane, with a weight ratio of activated alumina to 3-aminopropyltriethoxysilane of 1:0.3; maintain the reaction temperature at 50℃ and stir at 300 rpm for 2 hours; perform vacuum filtration, ethanol washing, and vacuum drying sequentially to prepare the silane-functionalized alumina matrix;

[0079] S2. Construction of Activated Silicic Acid Template: Weigh 100 parts of the silane-functionalized alumina matrix prepared in S1. Using a pulsed gradient assembly strategy, activated silicic acid was added in batches. First, 40% activated silicic acid was added, the pH was adjusted to 5.0, the temperature was raised to 30℃, and the reaction was stirred at 600 rpm for 10 min. Then, 30% activated silicic acid was added, the pH was adjusted to 5.0, the temperature was raised to 40℃, and the reaction was stirred at 500 rpm for 10 min. Finally, the remaining 30% activated silicic acid was added, the pH was adjusted to 5.0, the temperature was raised to 50℃, and the reaction was slowly matured at 300 rpm for 20 min. The weight ratio of silane-functionalized alumina matrix to activated silicic acid was 1:0.3. The pH of the system was adjusted using 0.5M sulfuric acid solution and 0.5M sodium hydroxide solution. After the reaction was completed, a gradient cooling strategy was adopted (10℃ intervals, each temperature step held for 15 min) to cool to room temperature. A silicon-alumina composite mixture was obtained, completing the construction of the activated silicic acid template.

[0080] S3. Loading of active sites with aluminum sulfate: 20 mL of the silicon-aluminum composite mixture prepared in S2 was placed in an ice bath. Aluminum sulfate solution (25 wt%) was injected in three portions. The first portion was 50% and immersed under vacuum pressure (-0.08 MPa) for 20 min. The second portion was 30% and immersed under normal pressure for 10 min. The third portion was 20% and immersed under vacuum pressure for 15 min. The volume ratio of silicon-aluminum composite mixture to aluminum sulfate was 1:1.

[0081] Figure 1 (a) is a TEM image of activated alumina, and (b) is a TEM image of the silane-bonded aluminum-silicon-based supramolecular defluorination coagulant prepared in this example (Example 8). Figure 1 As can be seen in (a): the activated alumina itself is spherical, from Figure 1As can be seen in (b), the surface of the activated alumina matrix has hydrolysis products of silica and aluminum salts. The hydrolysis products are in an extended state in water and have a polymer chain structure, so they can provide a large number of active sites to contact and flocculate pollutants. Its polymer network structure can adsorb multiple fluoride ions at the same time.

[0082] Weigh 25 mg of the silane-bonded aluminum-silicon-based supramolecular defluorination coagulant prepared in this example and 45 mg of commercially available aluminum sulfate, and place them separately in 1.0 L of water. Stir at 200 rpm for 0.5 min, then adjust the stirring speed to 35 rpm and continue stirring for 15 min. Take photos of the coagulation state of both. Figure 2 As shown, from Figure 2 As can be seen from this, compared with commercially available aluminum sulfate, the silane-bonded aluminum-silicon-based supramolecular defluorination coagulant in this embodiment (i.e., Example 8) produces flocs that are larger in size and easier to settle. This is because the alumina matrix can act as a coagulation nucleus, promoting solid-liquid separation during the coagulation process.

[0083] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a silane-bonded aluminum-silicon-based supramolecular defluorination coagulant, characterized in that, The process includes the following steps: mixing activated alumina and a silane coupling agent, heating and stirring under a nitrogen atmosphere to prepare a silane-functionalized alumina matrix; adding activated silicic acid to the silane-functionalized alumina matrix in batches using a pulsed gradient assembly strategy, adjusting the pH and reaction temperature of the reaction system in batches, and cooling to room temperature using a gradient cooling strategy after the reaction to complete the construction of the activated silicic acid template and prepare a silicon-aluminum composite mixture; injecting aluminum sulfate solution into the silicon-aluminum composite mixture in three batches under ice bath conditions, and simultaneously performing an impregnation reaction in three batches to complete the loading of aluminum sulfate active sites and prepare the silane-bonded aluminum-silicon-based supramolecular defluorination coagulant.

2. The preparation method according to claim 1, characterized in that, The weight ratio of the activated alumina to the silane coupling agent is 1:(0.2-0.5).

3. The preparation method according to claim 2, characterized in that, The weight ratio of the activated alumina to the silane coupling agent is 1:0.

3.

4. The preparation method according to claim 3, characterized in that, The temperature for the heating and stirring reaction is 50-70℃.

5. The preparation method according to claim 4, characterized in that, The temperature for the heating and stirring reaction is 50°C.

6. The preparation method according to claim 5, characterized in that, The weight ratio of the silane-functionalized alumina matrix to the activated silica is 1:0.

3.

7. The preparation method according to claim 6, characterized in that, The volume ratio of the silicon-aluminum composite mixture to the aluminum sulfate solution is 1:(1-2.5), and the concentration of the aluminum sulfate solution is 25 wt.%.

8. The preparation method according to claim 7, characterized in that, The volume ratio of the silicon-aluminum composite mixture to the aluminum sulfate solution is 1:

1.

9. A silane-bonded aluminum-silicon-based supramolecular defluorination coagulant prepared by the preparation method according to any one of claims 1-8.

10. The application of the silane-bonded aluminum-silicon-based supramolecular defluorination coagulant of claim 9 in the treatment of photovoltaic wastewater.

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