Multi-effect composite fluorine removal agent and application thereof in wastewater treatment

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a multi-effect composite fluorine removal agent and application thereof in wastewater treatment, and the multi-effect composite fluorine removal agent comprises the following raw materials in parts by weight: 60-80 parts of attapulgite, 40-60 parts of a composite additive, 20-30 parts of polyaluminum chloride and 20-30 parts of polyferric chloride. In the preparation process of the fluorine removal agent, after the composite additive is added, a three-dimensional network structure with a high specific surface area is constructed by modified powder in the base material and the multi-walled carbon nanotubes, rich adsorption channels are provided for fluorine ions, and graphene oxide and sodium alginate in the auxiliary material form a stable gel skeleton; rare earth elements such as lanthanum nitrate, zirconium oxychloride and the like provide specific fluorine binding sites, the aluminum-magnesium hydrotalcite further enhances the ion exchange capacity, and due to the multi-mechanism synergistic effect, the fluorine removal agent can still keep high adsorption efficiency in complex water.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a multi-effect composite defluorinating agent and its application in wastewater treatment. Background Technology

[0002] Composite defluoridating agents are a class of functional materials used for the advanced treatment of industrial wastewater. They remove fluoride ions from water through adsorption, precipitation, or ion exchange. Currently, activated alumina, bone char, or rare earth modified materials are commonly used as core components in this field. These materials can achieve basic defluoridation effects under specific conditions, providing a technical basis for the treatment of high-fluoride wastewater.

[0003] Currently, composite defluoridating agents often simply combine adsorbents such as activated alumina with flocculants. This results in a lack of synergistic effect between the limited active sites of the adsorbents and the non-specific charge neutralization of the flocculants. Furthermore, the floc structure formed during flocculation is unstable, failing to completely encapsulate fluoride ions and easily desorbing. Consequently, the composite defluoridating agent has insufficient adsorption capacity for low-concentration fluoride ions and exhibits poor stability under complex water quality conditions such as high salinity. Therefore, this invention provides a multi-effect composite defluoridating agent and its application in wastewater treatment. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-effect composite defluoridator and its application in wastewater treatment. The multi-effect composite defluoridator prepared by this invention has good treatment effect on different types of wastewater.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a multi-effect composite defluorinating agent, comprising the following raw materials in parts by weight: 60-80 parts attapulgite, 40-60 parts composite additives, 20-30 parts polyaluminum chloride, and 20-30 parts polyferric chloride; The composite additive is prepared by the following method: S1: Base material preparation. The raw materials for the base material include powder, multi-walled carbon nanotubes, DMF, modified resin, and deionized water. S2: Preparation of excipients, the raw materials of which include graphene oxide dispersion, sodium alginate, deionized water, lanthanum nitrate, zirconium oxychloride, and aluminum magnesium hydrotalcite powder. S3: Mixing treatment: The base material and auxiliary materials are stirred at 200-400 rpm for 40-60 minutes to complete the mixing treatment and obtain the composite additive.

[0006] Further, the method for preparing the base material is as follows: powder and multi-walled carbon nanotubes are dispersed in DMF and ultrasonically treated for 40-60 min. The resulting product is transferred to a reaction vessel, the reaction vessel is set at a temperature of 80-100℃, the stirring speed is 200-400 rpm, and the mixture is stirred at a constant temperature for 2-4 h. The resulting product is filtered and washed, and then placed in an oven and dried at 50-60℃ for 4-6 h to obtain a coarse material. The coarse material, modified resin, and deionized water are added to the reaction vessel, the reaction vessel is set at a temperature of 40-60℃, the stirring speed is 100-200 rpm, and the mixture is stirred at a constant temperature for 40-60 min. The resulting product is centrifuged to obtain a solid, which is then placed in an oven and dried at 50-70℃ for 4-6 h. The solid is then ground to 100 mesh to obtain the base material.

[0007] Furthermore, the mass ratio of powder, multi-walled carbon nanotubes, and DMF is 1:0.2 to 0.3:2, and the mass ratio of coarse material, modified resin, and deionized water is 1:0.25 to 0.35:2 to 3.

[0008] Further, the powder is prepared by the following method: corn stalk powder is soaked and washed in clean water, drained, dried, and ground to 200 mesh to obtain dry powder, which is set aside. Zinc nitrate, aluminum nitrate, cerium nitrate, and deionized water are added to a mixer, which is set to 100-200 rpm and stirred for 20-40 minutes to obtain mixture A, which is set aside. Urea is mixed with 15-20 times its mass of deionized water to obtain mixture B, which is set aside. The dry powder and mixture A are added to the reaction mixture. In the reactor, the stirring is set at 400-600 rpm for 40-60 minutes. Then, the reactor is heated to 40-50°C and stirred at a constant temperature of 80-100 rpm for 10-20 minutes. Mixture B is slowly added. The resulting product is centrifuged, and the supernatant is discarded to obtain the precipitate. The precipitate is washed three times alternately with deionized water and anhydrous ethanol. Then, it is placed in an oven and dried at 60-70°C for 8-10 minutes to obtain the powder.

[0009] Furthermore, the mass ratio of dry powder, mixture A, and mixture B is 1:2 to 3:1, and the mass ratio of zinc nitrate, aluminum nitrate, cerium nitrate, and deionized water is 1:0.2 to 0.4:0.1 to 0.2:6 to 8.

[0010] Further, the modified resin is prepared as follows: polyvinyl alcohol particles and DMF are added to a reaction vessel, the reaction vessel is heated to 80-90°C, ethylenediamine is slowly added dropwise, and the mixture is stirred at 100-200 rpm for 30-50 minutes. Nitrogen gas is introduced into the reaction vessel, phosphorus pentoxide is added, the temperature is raised to 110-120°C, and the mixture is stirred at 200-300 rpm for 20-40 minutes. After that, the mixture is allowed to cool naturally to room temperature. The resulting product is filtered to remove the liquid, washed with deionized water, and the resulting product is placed in an oven and dried at 40-60°C for 6-8 hours to obtain the modified resin.

[0011] Furthermore, the method for preparing the excipient is as follows: a mixture of graphene oxide dispersion, sodium alginate, and deionized water is prepared by mixing and treating the mixture. Lanthanum nitrate, zirconium oxychloride, and aluminum magnesium hydrotalcite powder are added to a mixer. The mixer is set to 60-80 rpm and stirred for 40-60 minutes. The resulting product is mixed with the mixture, ultrasonically treated, filtered, and dried to obtain the excipient.

[0012] Furthermore, the mass concentration of the graphene oxide dispersion is 0.6–1.5%, the mass ratio of the graphene oxide dispersion, sodium alginate, and deionized water is 1:0.1:1.5–2, the mass ratio of lanthanum nitrate, zirconium oxychloride, and aluminum magnesium hydrotalcite powder is 1:0.1–0.2:0.4–0.6, and the mass of lanthanum nitrate is 20–30% of the mass of the mixture.

[0013] Furthermore, the preparation method of the multi-effect composite defluorination agent includes the following steps: weighing each raw material as needed and adding it into a mixer, setting the mixer to 200-400 rpm and stirring for 1-2 hours to prepare the multi-effect composite defluorination agent.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. In this invention, after adding composite additives during the preparation of the defluoridator, the modified powder in the base material and multi-walled carbon nanotubes construct a three-dimensional network structure with a high specific surface area, providing abundant adsorption channels for fluoride ions. The graphene oxide and sodium alginate in the excipients form a stable gel framework, while rare earth elements such as lanthanum nitrate and zirconium oxychloride provide specific fluoride binding sites. Aluminum magnesium hydrotalcite further enhances the ion exchange capacity. This multi-mechanism synergistic effect enables the defluoridator to maintain high adsorption efficiency in complex water quality.

[0015] 2. In this invention, attapulgite serves as a substrate, providing abundant porous structures and initial adsorption sites. Polyaluminum chloride and polyferric chloride hydrolyze in water to generate various hydroxyl polymeric cations, which efficiently flocculate and co-precipitate fluorides through charge neutralization and adsorption bridging. The modified resin in the composite additive further introduces functional groups with strong complexing capabilities, which, together with the biomass-based active sites provided by the powder and the rare earth-specific sites in the excipients, constitute a multi-level adsorption system, thereby achieving rapid response and deep purification of low-concentration fluoride ions. Attached Figure Description

[0016] Figure 1 The present invention provides a flowchart of a multi-effect composite defluorinating agent and its application in wastewater treatment. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] It should be noted that the raw materials used in the following embodiments are all commercially available.

[0019] Example 1: A multi-effect composite defluorinating agent comprises the following raw materials in parts by weight: 60 parts attapulgite, 40 parts composite additives, 20 parts polyaluminum chloride, and 20 parts polyferric chloride; The composite additive is prepared by the following method: S1: Base material preparation. The raw materials for the base material include powder, multi-walled carbon nanotubes, DMF, modified resin, and deionized water. S2: Preparation of excipients, the raw materials of which include graphene oxide dispersion, sodium alginate, deionized water, lanthanum nitrate, zirconium oxychloride, and aluminum magnesium hydrotalcite powder. S3: Mixing treatment: The base material and auxiliary materials are stirred at 200 rpm for 40 minutes to complete the mixing treatment and obtain the composite additive.

[0020] The method for preparing the base material is as follows: powder and multi-walled carbon nanotubes are dispersed in DMF and ultrasonically treated for 40 min. The resulting product is transferred to a reaction vessel, the reaction vessel is set at 80℃ and the stirring speed is 200 rpm, and the mixture is stirred at a constant temperature for 2 h. The resulting product is filtered, washed, and placed in an oven, which is set at 50℃ and dried for 4 h to obtain coarse material. The coarse material, modified resin, and deionized water are added to the reaction vessel, the reaction vessel is set at 40℃ and the stirring speed is 100 rpm, and the mixture is stirred at a constant temperature for 40 min. The resulting product is centrifuged to obtain solid material, which is then placed in an oven, which is set at 50℃ and dried for 4 h. The solid material is then ground to 100 mesh to obtain the base material. The mass ratio of powder, multi-walled carbon nanotubes, and DMF is 1:0.2:2, and the mass ratio of coarse material, modified resin, and deionized water is 1:0.25:2.

[0021] The powder is prepared by the following method: corn stalk powder is soaked and washed in clean water, drained, dried, and ground to 200 mesh to obtain dry powder, which is then set aside. Zinc nitrate, aluminum nitrate, cerium nitrate, and deionized water are added to a mixer, which is set to 100 rpm and stirred for 20 minutes to obtain mixture A, which is then set aside. Urea is mixed with 15 times its mass of deionized water to obtain mixture B, which is then set aside. The dry powder and mixture A are added to a reaction vessel, which is set to 400 rpm and stirred for 40 minutes. The reactor was then heated to 40°C and stirred at a constant temperature of 80 rpm for 10 minutes. Mixture B was slowly added, and the resulting product was centrifuged. The supernatant was discarded to obtain the precipitate. The precipitate was washed three times alternately with deionized water and anhydrous ethanol. Then, it was placed in an oven and dried at 60°C for 8 minutes to obtain the powder. The mass ratio of the dry powder, mixture A, and mixture B was 1:2:1, and the mass ratio of zinc nitrate, aluminum nitrate, cerium nitrate, and deionized water was 1:0.2:0.1:6.

[0022] The modified resin is prepared as follows: polyvinyl alcohol particles and DMF are added to a reactor, the reactor is heated to 80°C, ethylenediamine is slowly added dropwise, and the mixture is stirred at 100 rpm for 30 min. Nitrogen gas is introduced into the reactor, phosphorus pentoxide is added, the temperature is raised to 110°C, and the mixture is stirred at 200 rpm for 20 min. After that, the mixture is allowed to cool naturally to room temperature. The resulting product is filtered to remove the liquid, washed with deionized water, and the resulting product is placed in an oven and dried at 40°C for 6 h to obtain the modified resin.

[0023] The method for preparing the excipient is as follows: graphene oxide dispersion, sodium alginate, and deionized water are mixed at a mass ratio of 1:0.1:1.5 to obtain a mixed solution. Then, lanthanum nitrate, zirconium oxychloride, and aluminum magnesium hydrotalcite powder are added to a mixer at a mass ratio of 1:0.1:0.4. The mixer is set to 60 rpm and stirred for 40 minutes. The resulting product is mixed with the mixed solution, ultrasonically treated, filtered, and dried to obtain the excipient. The mass concentration of the graphene oxide dispersion is 0.6%, and the mass of lanthanum nitrate is 20% of the mass of the mixed solution.

[0024] The preparation method of the multi-effect composite defluorination agent includes the following steps: weigh each raw material as needed and add it to a mixer, set the mixer to 200 rpm and stir for 1 hour to prepare the multi-effect composite defluorination agent.

[0025] Example 2: A multi-effect composite defluorinating agent comprises the following raw materials in parts by weight: 70 parts attapulgite, 50 parts composite additives, 25 parts polyaluminum chloride, and 25 parts polyferric chloride. The composite additive is prepared by the following method: S1: Base material preparation. The raw materials for the base material include powder, multi-walled carbon nanotubes, DMF, modified resin, and deionized water. S2: Preparation of excipients, the raw materials of which include graphene oxide dispersion, sodium alginate, deionized water, lanthanum nitrate, zirconium oxychloride, and aluminum magnesium hydrotalcite powder. S3: Mixing treatment: The base material and auxiliary materials are stirred at 300 rpm for 50 minutes to complete the mixing treatment and obtain the composite additive.

[0026] The method for preparing the base material is as follows: powder and multi-walled carbon nanotubes are dispersed in DMF and ultrasonically treated for 50 min. The resulting product is transferred to a reaction vessel, the reaction vessel is set at a temperature of 90℃ and a stirring speed of 300 rpm, and the mixture is stirred at a constant temperature for 3 h. The resulting product is filtered, washed, and placed in an oven, which is set at 55℃ and dried for 5 h to obtain coarse material. The coarse material, modified resin, and deionized water are added to the reaction vessel, the reaction vessel is set at a temperature of 50℃ and a stirring speed of 150 rpm, and the mixture is stirred at a constant temperature for 50 min. The resulting product is centrifuged to obtain solid material, which is then placed in an oven, which is set at 60℃ and dried for 5 h. The solid material is then ground to 100 mesh to obtain the base material. The mass ratio of powder, multi-walled carbon nanotubes, and DMF is 1:0.25:2, and the mass ratio of coarse material, modified resin, and deionized water is 1:0.3:2.5.

[0027] The powder is prepared by the following method: corn stalk powder is soaked and washed in clean water, drained, dried, and ground to 200 mesh to obtain dry powder, which is set aside. Zinc nitrate, aluminum nitrate, cerium nitrate, and deionized water are added to a mixer and stirred at 150 rpm for 30 minutes to obtain mixture A, which is set aside. Urea is mixed with 18 times its mass of deionized water to obtain mixture B, which is set aside. The dry powder and mixture A are added to a reaction vessel and stirred at 500 rpm for 50 minutes. After that, The reactor was heated to 45°C and stirred at a constant temperature of 90 rpm for 15 minutes. Mixture B was slowly added, and the resulting product was centrifuged. The supernatant was discarded to obtain the precipitate. The precipitate was washed three times alternately with deionized water and anhydrous ethanol. Then, it was placed in an oven and dried at 65°C for 9 minutes to obtain the powder. The mass ratio of dry powder, mixture A, and mixture B was 1:2.5:1, and the mass ratio of zinc nitrate, aluminum nitrate, cerium nitrate, and deionized water was 1:0.3:0.15:7.

[0028] The modified resin is prepared as follows: polyvinyl alcohol particles and DMF are added to a reaction vessel, the reaction vessel is heated to 85°C, ethylenediamine is slowly added dropwise, and the mixture is kept at 150 rpm and stirred for 40 min. Nitrogen gas is introduced into the reaction vessel, phosphorus pentoxide is added, the temperature is raised to 115°C, and the mixture is kept at 250 rpm and stirred for 30 min. After that, the mixture is allowed to cool naturally to room temperature. The resulting product is filtered to remove the liquid, washed with deionized water, and the resulting product is sent to an oven and dried at 50°C for 7 h to obtain the modified resin.

[0029] The method for preparing the excipient is as follows: graphene oxide dispersion, sodium alginate, and deionized water are mixed at a mass ratio of 1:0.1:1.8 to obtain a mixed solution. Then, lanthanum nitrate, zirconium oxychloride, and aluminum magnesium hydrotalcite powder are added to a mixer at a mass ratio of 1:0.15:0.5. The mixer is set to 70 rpm and stirred for 50 minutes. The resulting product is mixed with the mixed solution, ultrasonically treated, filtered, and dried to obtain the excipient. The mass concentration of the graphene oxide dispersion is 1.2%, and the mass of lanthanum nitrate is 25% of the mass of the mixed solution.

[0030] The preparation method of the multi-effect composite defluorination agent includes the following steps: weigh each raw material as needed and add it to a mixer, set the mixer to 300 rpm and stir for 1.5 hours to prepare the multi-effect composite defluorination agent.

[0031] Example 3: A multi-effect composite defluorinating agent comprises the following raw materials in parts by weight: 80 parts attapulgite, 60 parts composite additives, 30 parts polyaluminum chloride, and 30 parts polyferric chloride; The composite additive is prepared by the following method: S1: Base material preparation. The raw materials for the base material include powder, multi-walled carbon nanotubes, DMF, modified resin, and deionized water. S2: Preparation of excipients, the raw materials of which include graphene oxide dispersion, sodium alginate, deionized water, lanthanum nitrate, zirconium oxychloride, and aluminum magnesium hydrotalcite powder. S3: Mixing treatment: The base material and auxiliary materials are stirred at 400 rpm for 60 min to complete the mixing treatment and obtain the composite additive.

[0032] The method for preparing the base material is as follows: powder and multi-walled carbon nanotubes are dispersed in DMF and ultrasonically treated for 60 min. The resulting product is transferred to a reaction vessel, the reaction vessel is set at 100℃ and the stirring speed is 400 rpm, and the mixture is stirred at a constant temperature for 4 h. The resulting product is filtered, washed, and placed in an oven, which is set at 60℃ and dried for 6 h to obtain coarse material. The coarse material, modified resin, and deionized water are added to the reaction vessel, the reaction vessel is set at 60℃ and the stirring speed is 200 rpm, and the mixture is stirred at a constant temperature for 60 min. The resulting product is centrifuged to obtain solid material, which is then placed in an oven, which is set at 70℃ and dried for 6 h. The solid material is then ground to 100 mesh to obtain the base material. The mass ratio of powder, multi-walled carbon nanotubes, and DMF is 1:0.3:2, and the mass ratio of coarse material, modified resin, and deionized water is 1:0.35:3.

[0033] The powder is prepared by the following method: corn stalk powder is soaked and washed in clean water, drained, dried, and ground to 200 mesh to obtain dry powder, which is set aside. Zinc nitrate, aluminum nitrate, cerium nitrate, and deionized water are added to a mixer and stirred at 200 rpm for 40 minutes to obtain mixture A, which is set aside. Urea is mixed with 20 times its mass of deionized water to obtain mixture B, which is set aside. The dry powder and mixture A are added to a reaction vessel and stirred at 600 rpm for 60 minutes. The reactor was heated to 50°C and stirred at a constant temperature of 100 rpm for 20 minutes. Mixture B was slowly added, and the resulting product was centrifuged. The supernatant was discarded to obtain the precipitate. The precipitate was washed three times alternately with deionized water and anhydrous ethanol. Then, it was placed in an oven and dried at 70°C for 10 minutes to obtain the powder. The mass ratio of dry powder, mixture A, and mixture B was 1:3:1, and the mass ratio of zinc nitrate, aluminum nitrate, cerium nitrate, and deionized water was 1:0.4:0.2:8.

[0034] The modified resin is prepared as follows: polyvinyl alcohol particles and DMF are added to a reaction vessel, the reaction vessel is heated to 90°C, ethylenediamine is slowly added dropwise, the mixture is kept at 200 rpm and stirred for 50 min, nitrogen gas is introduced into the reaction vessel, phosphorus pentoxide is added, the temperature is raised to 120°C, the mixture is kept at 300 rpm and stirred for 40 min, and then allowed to cool naturally to room temperature. The resulting product is filtered to remove the liquid, washed with deionized water, and the resulting product is sent to an oven and dried at 60°C for 8 h to obtain the modified resin.

[0035] The method for preparing the excipient is as follows: graphene oxide dispersion, sodium alginate, and deionized water are mixed at a mass ratio of 1:0.1:2 to obtain a mixed solution. Then, lanthanum nitrate, zirconium oxychloride, and aluminum magnesium hydrotalcite powder are added to a mixer at a mass ratio of 1:0.2:0.6. The mixer is set to 80 rpm and stirred for 60 minutes. The resulting product is mixed with the mixed solution, ultrasonically treated, filtered, and dried to obtain the excipient. The mass concentration of the graphene oxide dispersion is 1.5%, and the mass of lanthanum nitrate is 30% of the mass of the mixed solution.

[0036] The preparation method of the multi-effect composite defluorination agent includes the following steps: weigh each raw material as needed and add it to a mixer, set the mixer to 400 rpm and stir for 2 hours to prepare the multi-effect composite defluorination agent.

[0037] Comparative Example 1: The difference between this comparative example and Example 1 is that this comparative example does not contain any compound additives.

[0038] Comparative Example 2 differs from Example 1 in that it does not contain any excipients.

[0039] Comparative Example 3 differs from Example 1 in that it does not contain a base material.

[0040] Performance testing: 1. Test wastewater preparation Low-fluoride wastewater: Prepare simulated wastewater with an initial fluoride ion concentration of 5.0 mg / L, total dissolved solids of 500 mg / L, and pH of 7.0. This concentration simulates wastewater that still requires deep purification after primary treatment. High salinity wastewater: Prepare simulated wastewater with an initial fluoride ion concentration of 15.0 mg / L. Increase the total dissolved solids to 5000 mg / L by adding sodium chloride, and add 100 mg / L of calcium and magnesium ions to simulate hardness interference. The pH value is 7.0. This condition simulates high salinity and high fluoride wastewater from petrochemical, chemical and other industries. Conventional industrial wastewater: Prepare simulated wastewater with an initial fluoride ion concentration of 30.0 mg / L, total dissolved solids controlled at 1000 mg / L, and pH value of 7.0. These conditions simulate conventional industrial wastewater discharge.

[0041] 2. Test Procedure: Take 1 L of any of the above-mentioned simulated wastewater into a beaker. Weigh the defluoridating agent samples prepared in Examples 1-3 and Comparative Examples 1-3 at a dosage of 10 g / L and add them to the wastewater. Stir rapidly at 200 rpm for 10 minutes, then stir slowly at 60 rpm for 5 minutes. After standing and settling for 30 minutes, take the supernatant to detect the fluoride ion concentration and record it in Table 1. At the same time, calculate the fluoride ion removal rate and record it in Table 1. The calculation formula is: Removal rate (%) = (fluoride ion concentration before treatment - fluoride ion concentration after treatment) / fluoride ion concentration before treatment × 100%.

[0042] Table 1:

[0043] Observation and analysis of the data in the table show that the multi-effect composite defluoridator prepared by the methods in Examples 1-3 outperforms the comparative examples 1-3 in treating different types of wastewater. This indicates that the perfect synergy between the base material and auxiliary materials in the composite additives of Examples 1-3 constructs a highly efficient defluoridation system. Further analysis shows that it is excellent in dealing with low fluoride concentrations, indicating that the rare earth elements lanthanum nitrate and zirconium oxychloride in the auxiliary materials have extremely high affinity and selectivity for fluoride ions, and can accurately capture fluoride ions at low concentrations, solving the problem that traditional materials are difficult to capture fluoride ions at low concentrations. The high specific surface area provided by the multi-walled carbon nanotubes and powder in the base material... The high-density distribution of these specific sites was ensured, and the excellent effect in dealing with high-salinity wastewater proved the key role of the stable gel network formed by sodium alginate and modified resin in the excipients. This network can effectively encapsulate flocs, resist the damage of high ionic strength to the flocculation process, and prevent fluoride ion desorption. At the same time, the ion exchange effect of aluminum magnesium hydrotalcite is still effective in high-salinity environments. When treating conventional industrial wastewater, the fluoride ion removal rate can reach more than 85%. This shows that the multi-effect composite defluoridator prepared in Examples 1-3 can be applied to wastewater with different water quality conditions through physical adsorption, chemical bonding, ion exchange, and stabilization and solidification.

[0044] Further analysis of the data in the table shows that the performance of Comparative Example 1, which lacks the composite additive, completely collapsed, and its performance was the worst in different water qualities. This is because Comparative Example 1 only has attapulgite clay, polyaluminum chloride, and polyferric chloride in a simple compound. Without the entire composite additive system, the material lacks a high-density heterogeneous site system, which cannot effectively capture low concentrations of fluoride ions. The lack of a stable framework system makes the flocs formed by polyaluminum chloride and polyferric chloride unstable under high salinity and easily broken down, leading to the re-release of fluoride ions. The poor anti-interference ability means that high concentrations of competing ions will shield the charge neutralization effect of polyaluminum chloride and polyferric chloride, thus causing a sharp decline in various performances. The performance of Comparative Example 2, which lacked excipients, was higher than that of Comparative Example 1 but lower than that of Comparative Example 3. This is because the absence of excipients means the loss of rare earth elements, which directly leads to the loss of the high selective adsorption capacity for fluoride ions. Therefore, the effect is poor at low concentrations. At the same time, the absence of the gel network system leads to insufficient stability of the floc structure. The performance will be severely degraded under high salt interference. The absence of aluminum magnesium hydrotalcite weakens the ion exchange supplementary mechanism, which also shows that the excipients mainly contribute to the specific adsorption function and structural stability function. In contrast, Comparative Example 3, which lacked the base material, outperformed Comparative Example 2 in all water qualities, but was still far inferior to the Example. This is because the lack of the base material means the loss of the three-dimensional network framework constructed by the powder and multi-walled carbon nanotubes, resulting in a decrease in the specific surface area and total adsorption capacity of the material. Although the specific sites provided by the excipients are still there, the lack of sufficient framework support makes it difficult for these sites to be fully utilized, leading to a decline in performance.

[0045] To further verify the actual treatment effect of the material of the present invention under different water qualities, the following application tests were conducted: The wastewater was prepared by the above-mentioned method of mixing low-fluoride concentration wastewater, high-salinity wastewater and conventional industrial wastewater. The test samples were set as Application Example 1, Application Example 2 and Application Example 3. The difference between Application Example 1 and Example 1 is that Application Example 1 was tested with a dosage of 6 g / L, Application Example 2 was tested with a dosage of 10 g / L, and Application Example 3 was tested with a dosage of 15 g / L. The data obtained are recorded in Table 2. Table 2:

[0046] Analysis of the data in Table 2 shows that when the multi-effect composite defluoridator prepared by this invention is used in different types of wastewater, a dosage of 6 g / L can achieve good treatment results for different types of wastewater. When the dosage reaches 10 g / L, the fluoride ion removal rate can reach more than 85% for different types of wastewater, which is excellent. Moreover, the removal rate will further increase with the increase of dosage, which also shows that a dosage range of 6 to 15 g / L can achieve good treatment results for wastewater.

[0047] By comparing and analyzing the relevant data in the table, it can be seen that the multi-effect composite defluoridator prepared by this invention has good treatment effects on different types of wastewater. This indicates that the multi-effect composite defluoridator provided by this invention has a broader market prospect and is more suitable for widespread application.

[0048] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0049] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A multi-effect composite defluorinating agent, characterized in that: It includes the following raw materials in parts by weight: 60-80 parts attapulgite, 40-60 parts composite additives, 20-30 parts polyaluminum chloride, and 20-30 parts polyferric chloride; The composite additive is prepared by the following method: S1: Base material preparation. The raw materials for the base material include powder, multi-walled carbon nanotubes, DMF, modified resin, and deionized water. S2: Preparation of excipients, the raw materials of which include graphene oxide dispersion, sodium alginate, deionized water, lanthanum nitrate, zirconium oxychloride, and aluminum magnesium hydrotalcite powder. S3: Mixing treatment: The base material and auxiliary materials are stirred at 200-400 rpm for 40-60 minutes to complete the mixing treatment and obtain the composite additive.

2. The multi-effect composite defluorinating agent according to claim 1, characterized in that, The method for preparing the base material is as follows: powder and multi-walled carbon nanotubes are dispersed in DMF and ultrasonically treated for 40-60 min. The resulting product is transferred to a reaction vessel, the reaction vessel is set at a temperature of 80-100℃ and a stirring speed of 200-400 rpm, and the mixture is stirred at a constant temperature for 2-4 h. The resulting product is filtered, washed, and placed in an oven, which is set at 50-60℃ for drying for 4-6 h to obtain a coarse material. The coarse material, modified resin, and deionized water are added to the reaction vessel, the reaction vessel is set at a temperature of 40-60℃ and a stirring speed of 100-200 rpm, and the mixture is stirred at a constant temperature for 40-60 min. The resulting product is centrifuged to obtain a solid. The solid is sent to an oven, which is set at 50-70℃ for drying for 4-6 h and then ground to 100 mesh to obtain the base material.

3. The multi-effect composite defluorinating agent according to claim 2, characterized in that, The mass ratio of powder, multi-walled carbon nanotubes, and DMF is 1:0.2 to 0.3:2, and the mass ratio of coarse material, modified resin, and deionized water is 1:0.25 to 0.35:2 to 3.

4. The multi-effect composite defluorinating agent according to claim 2, characterized in that, The powder is prepared by the following method: Corn stalk powder is soaked and washed in clean water, drained, dried, and ground to 200 mesh to obtain dry powder, which is set aside. Zinc nitrate, aluminum nitrate, cerium nitrate, and deionized water are added to a mixer and stirred at 100-200 rpm for 20-40 minutes to obtain mixture A, which is set aside. Urea is mixed with 15-20 times its mass of deionized water to obtain mixture B, which is set aside. The dry powder and mixture A are added to a reaction vessel and stirred at 400-600 rpm for 40-60 minutes. Then, the reaction vessel is heated to 40-50°C and stirred at a constant temperature of 80-100 rpm for 10-20 minutes. Mixture B is slowly added. The resulting product is centrifuged, and the supernatant is discarded to obtain precipitate. The precipitate is washed three times alternately with deionized water and anhydrous ethanol, and then dried in an oven at 60-70°C for 8-10 minutes to obtain the powder.

5. The multi-effect composite defluorinating agent according to claim 4, characterized in that, The mass ratio of dry powder, mixture A, and mixture B is 1:2 to 3:1, and the mass ratio of zinc nitrate, aluminum nitrate, cerium nitrate, and deionized water is 1:0.2 to 0.4:0.1 to 0.2:6 to 8.

6. The multi-effect composite defluorinating agent according to claim 5, characterized in that, The modified resin is prepared as follows: polyvinyl alcohol particles and DMF are added to a reaction vessel, the temperature of the reaction vessel is set to 80-90°C, ethylenediamine is slowly added dropwise, and the mixture is stirred at 100-200 rpm for 30-50 minutes. Nitrogen gas is introduced into the reaction vessel, phosphorus pentoxide is added, the temperature is raised to 110-120°C, and the mixture is stirred at 200-300 rpm for 20-40 minutes. After that, the mixture is allowed to cool naturally to room temperature. The resulting product is filtered to remove the liquid, washed with deionized water, and the resulting product is placed in an oven and dried at 40-60°C for 6-8 hours to obtain the modified resin.

7. The multi-effect composite defluorinating agent according to claim 1, characterized in that, The method for preparing the excipient is as follows: a mixture of graphene oxide dispersion, sodium alginate, and deionized water is prepared. Lanthanum nitrate, zirconium oxychloride, and aluminum magnesium hydrotalcite powder are added to a mixer. The mixer is set to 60-80 rpm and stirred for 40-60 minutes. The resulting product is mixed with the mixture, ultrasonically treated, filtered, and dried to obtain the excipient.

8. The multi-effect composite defluorinating agent according to claim 7, characterized in that, The mass concentration of the graphene oxide dispersion is 0.6-1.5%, the mass ratio of graphene oxide dispersion, sodium alginate, and deionized water is 1:0.1:1.5-2, the mass ratio of lanthanum nitrate, zirconium oxychloride, and aluminum magnesium hydrotalcite powder is 1:0.1-0.2:0.4-0.6, and the mass of lanthanum nitrate is 20-30% of the mass of the mixture.

9. The preparation method of the multi-effect composite defluorinating agent according to claims 1 to 8, characterized in that, Includes the following steps: Weigh out each raw material as needed and add it to the mixer. Set the mixer to 200-400 rpm and stir for 1-2 hours to produce a multi-effect composite defluorinating agent.

10. The application of the multi-effect composite defluorinating agent prepared by the preparation method according to claim 9, characterized in that, The dosage of the multi-effect compound defluoridator in wastewater is 6–15 g / L.

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