Adsorbent for synergic resourceful treatment of fluorine-containing wastewater and preparation method and application thereof

Abstract

The application relates to the field of fluorine-containing wastewater treatment, and in particular to a kind of adsorbent for synergistically resourceful treatment of fluorine-containing wastewater and its preparation method and application, which is prepared into molecular sieve or porous ceramic by hydrothermal reaction and subsequent treatment of electrolytic manganese slag and antimony tailings, the dissolution of metals in antimony tailings is controlled by the oxidizing property of manganese, and the high selectivity adsorption of antimony is used to form better fluorine ion adsorption performance, which can overall give consideration to industrial waste recycling while preparing fluorine ion adsorbent with high adsorption, low adsorption equilibrium concentration, high adsorption kinetic tendency and safety and reliability.

Description

Technical Field

[0001] This application relates to the field of fluoride-containing wastewater treatment, and in particular to an adsorbent for synergistic resource-based treatment of fluoride-containing wastewater, its preparation method, and its application. Background Technology

[0002] Fluorine is an essential trace element for the human body, but excessive intake can lead to a series of serious health problems, including dental fluorosis, skeletal fluorosis, and damage to the nervous system. Nearly 200 million people worldwide are at risk of drinking water with excessive fluoride levels. Fluoride pollution in water bodies originates from both the natural weathering of fluoride-containing minerals and acidic fluoride-containing wastewater discharged during industrial production processes such as metallurgy, fertilizers, semiconductors, and glass ceramics. This type of wastewater typically has high fluoride concentrations and complex compositions, making its effective treatment a serious challenge in the environmental field.

[0003] Currently, common methods for treating fluoride-containing wastewater mainly include chemical precipitation, coagulation, adsorption, and membrane separation. Among these, traditional commercial adsorbents, such as functionalized resins, offer good performance but may be limited by high cost or a narrow pH application window. Chemical precipitation (usually using calcium salts, such as calcium oxide and calcium chloride) is suitable for treating high-concentration fluoride wastewater, removing fluoride by forming calcium fluoride (CaF2) precipitate. However, it suffers from problems such as large precipitate volume, difficult sludge disposal, and limited effectiveness in treating low-concentration fluoride. In existing technologies, chemical precipitation is typically used to pretreat high-concentration fluoride wastewater, followed by adsorption to further treat low-concentration fluoride wastewater. This approach balances efficiency, cost, and treatment effectiveness in the treatment of high-concentration fluoride wastewater.

[0004] Many industrial solid wastes, such as calcium carbide slag (mainly composed of Ca(OH)2), electrolytic manganese slag, and antimony tailings, are produced in huge quantities. Their stockpiling not only occupies land but also poses environmental risks. If these waste residues can be utilized as resources and developed into water treatment materials, it is possible to achieve "waste-to-waste treatment" and value-added utilization of solid waste, which meets the requirements of green and sustainable development. Summary of the Invention

[0005] The purpose of this application is to provide a waste-to-waste approach for treating fluoride-containing wastewater. It utilizes waste materials such as electrolytic manganese slag and antimony tailings to prepare adsorbents for treating fluoride-containing wastewater. These adsorbents can treat fluoride-containing wastewater at lower concentrations, have a wide applicable pH range, and a low adsorption equilibrium concentration.

[0006] First, this application provides a method for preparing an adsorbent for the synergistic resource recovery treatment of fluoride-containing wastewater, comprising the following steps: S1. Electrolytic manganese slag and antimony tailings are subjected to an alkaline environment and their crystalline phases are destroyed through a hydrothermal reaction to obtain a slurry. S2. Prepare an adsorbent from the slurry according to at least one of step a or step b: a. After aging, the slurry is prepared into zeolite molecular sieves; b. Add a pore-forming agent to the slurry, and after sintering, prepare porous ceramics; In step S1, the mass ratio of electrolytic manganese slag to antimony tailings is 1:1 to 1:10.

[0007] In the above scheme, two typical industrial solid wastes, electrolytic manganese slag and antimony tailings, are used as the main raw materials. Through hot alkaline treatment, active silicon and aluminum components are released, realizing the green circular economy concept of "treating waste with waste." This system can be used to prepare zeolite molecular sieves or as a solid adsorbent. Hydrothermal aging forms a microporous structure, significantly increasing the material's specific surface area. Simultaneously, ceramic structural modification provides better mechanical strength, making it suitable for continuous industrial operation and offering more possibilities for product usability.

[0008] Building upon the above, electrolytic manganese slag primarily serves as a source of active metal potentials in the system, providing manganese oxide and iron oxide. During the alkaline hydrothermal reaction, it can be converted into hydrated manganese oxide and hydrated iron oxide. Utilizing the principle of coordination exchange, it can specifically capture and adsorb fluorine atoms from wastewater, endowing the adsorbent with high selectivity and higher adsorption capacity. On the other hand, the residual manganese dioxide can also accelerate the oxidative decomposition of sulfide minerals in antimony tailings, promoting the overall crystal phase destruction kinetics. Furthermore, during ceramic sintering, manganese dioxide can provide additional crystal transformation structures, preventing excessive shrinkage and deformation of the ceramic body, while also providing higher porosity.

[0009] The main active components in antimony tailings are silicon dioxide and alumina. Under hydrothermal conditions, these components, along with trace amounts of silicon dioxide and alumina in electrolytic manganese slag, undergo crystalline phase disruption and dissolution, providing orthosilicic acid and aluminate anions. On one hand, these anions can serve as precursors for constructing zeolite molecular frameworks or the basic framework of ceramics, adjusting the appropriate silicon / aluminum ratio to compensate for the high silicon-aluminum ratio in single electrolytic manganese slag. On the other hand, the small amounts of antimony trioxide, antimony pentoxide, and some alkali metals in the antimony tailings can form low-melting-point phases during ceramic sintering, helping to lower the overall sintering temperature and improve the mechanical strength of the ceramics. Furthermore, the residual manganese oxide in the electrolytic manganese slag also has a certain weak oxidizing effect, inhibiting the dissolution of arsenic and antimony in the antimony tailings and reducing the leaching and migration of heavy metals.

[0010] By combining electrolytic manganese slag and antimony tailings in a mass ratio range of 1:1 to 1:10, not only can the above effects be achieved, but also an antimony-hydroxyl structure can be introduced into the manganese-iron adsorption system. By utilizing the stronger electronegativity of antimony to form a multidentate coordination network, not only can the selectivity for fluoride ions be improved, but also the adsorption kinetics can be improved, allowing the whole system to reach adsorption equilibrium more quickly.

[0011] Preferably, in step S1, water glass is also added. The amount of water glass added, calculated as silicon dioxide, is 5% to 20% of the total mass of electrolytic manganese slag and antimony tailings.

[0012] In the aforementioned system, water glass, as an additional silicon source, allows for more ideal control of the silicon-to-alumina ratio, ensuring the formation of X-type or A-type highly crystalline molecular sieves from zeolite, or the formation of a mullite-glass phase composite structure via a ceramic pathway. Simultaneously, the active silicate provided by water glass can reduce the amount of alkali required, improving overall strength, providing a buffering effect for the hydrothermal reaction, and enhancing the controllability of the hydrothermal reaction.

[0013] In addition, water glass can also play a certain structural guiding role in the system. It can act as a precursor in the formation of zeolite crystals, reducing the aging time required, and it can also act as a binder to improve the strength of porous ceramics. Furthermore, for antimony tailings, the addition of water glass can significantly reduce the leaching of arsenic, further reducing the safety risks of the aforementioned adsorbents.

[0014] Preferably, in step S2, the slurry is prepared into a zeolite molecular sieve, and in step S1, the modulus of the water glass is 2.5 to 3.0; or, In step S2, the slurry is prepared into a porous ceramic, and in step S1, the water glass modulus is 1.5 to 2.0.

[0015] In the above scheme, two different water glasses were used for the two synthesis routes. Water glass with a modulus of 2.5 to 3.0 was used in the molecular sieve system, which did not introduce excessive sodium ions. This helped to control the formation of highly crystalline X-type zeolite, maintain higher ion exchange capacity and higher fluoride ion capacity.

[0016] In ceramic sintering systems, the use of low-modulus water glass, with its higher alkali content, can significantly lower the sintering temperature. This not only reduces energy consumption but also enables the glassy solidification of heavy metals such as antimony and arsenic at lower temperatures, avoiding the problems of heavy metal volatilization and excessive energy consumption caused by high temperatures. Furthermore, low-modulus water glass can introduce more sodium oxide, which more easily promotes the entry of antimony and arsenic into the tetrahedral network formed by silicates, significantly reducing the leaching performance of arsenic and antimony in the system.

[0017] Preferably, in step S2, the slurry is prepared into a porous ceramic. After preparation, the porous ceramic is subjected to re-etching treatment with an alkaline solution. The molar concentration of the alkaline solution is 0.1-1M (calculated as hydroxide), the etching temperature is 40-60℃, and the etching time is 10-30min.

[0018] In the above scheme, an alkaline etching process is further introduced. Its main purpose is to treat excess water glass system to prevent it from clogging the micropores in the ceramic system. Simultaneously, the alkaline treatment can further create an uneven microstructure on the pore walls, increasing the specific surface area. Furthermore, the alkaline treatment can also further increase the hydroxyl content on the surface of the microporous ceramic, thereby improving its adsorption capacity and rate for fluoride ions.

[0019] Preferably, in step S2, the slurry is prepared into a zeolite molecular sieve, and the mass ratio of electrolytic manganese slag to antimony tailings is 1:2 to 1:6, and the amount of water glass added is 5% to 10% of the total mass of electrolytic manganese slag and antimony tailings; or, In step S2, the slurry is prepared into porous ceramics, and in step S1, the mass ratio of electrolytic manganese slag to antimony tailings is 1:6 to 1:8, and the amount of water glass added is 15% to 20% of the total mass of electrolytic manganese slag and antimony tailings.

[0020] In the above scheme, a lower water glass content is used in the zeolite path. The main purpose is to better control the silicon-aluminum ratio, so that the aging process forms zeolite molecular sieves with a higher specific surface area and a more regular pore structure. Overall, it has a lower diffusion resistance to fluoride ions, which greatly improves the adsorption capacity and equilibrium rate of fluoride ions, while also avoiding pore blockage caused by excessive silicon addition.

[0021] In the ceramic pathway, water glass with a low modulus and a higher doping level is used, which can provide better fluxing effect and better encapsulation of metals such as arsenic and antimony. At the same time, sufficient mechanical strength can be obtained through sintering to meet the requirements of industrial adsorption.

[0022] Preferably, the water glass is diluted with water to a density of 1.2–1.3 g / cm³ before being added. 3 ; And / or, In step S1, the electrolytic manganese slag, antimony tailings and alkaline solution are first hydrated. After the reaction is completed, the temperature is lowered to no higher than 40°C, and then water glass is added. Then step S2 is carried out directly.

[0023] In the above scheme, the water glass is diluted before being added to the system mainly to prevent it from reacting rapidly with calcium and magnesium ions in the slurry to form localized calcium silicate agglomerates, which would lead to unevenness in the reaction system. Simultaneously, in the above reaction process, a hydrothermal reaction is carried out first, followed by cooling before adding the water glass. After the hydrothermal reaction, at a lower temperature, silicate ions can react with silicon and aluminum compounds in the system to form precursors of oligomeric aluminosilicates, which is beneficial for subsequent zeolite crystallization or ceramic forming.

[0024] Preferably, in step S1, the pH value is 10-12, and / or, In step S1, the temperature of the hydrothermal reaction is 70–100°C, and / or, In step S1, the reaction time is 2–6 hours, and / or, In step S1, the solid-liquid ratio of electrolytic manganese slag and antimony tailings to alkaline solution is 0.2–1 g / ml.

[0025] Based on the above reaction conditions, the quartz phase and silicate glass structure in the system can be basically destroyed, while the aluminum will not be excessively dissolved, causing the aluminum-silicon ratio to run out of control. Overall, the above reaction conditions are mild, the equipment requirements are low, and controlling the solid-liquid ratio can ensure good fluidity while reducing the use of alkali solution and subsequent wastewater treatment costs.

[0026] Preferably, in step S2, the slurry is prepared into a zeolite molecular sieve, and the specific preparation method is as follows: The slurry was cooled to 10–40°C, and then 1–5 times the mass of the initial electrolytic manganese slag and antimony tailings were added to deionized water. The mixture was allowed to stand and age for 12–24 hours, and then filtered, washed and dried to obtain molecular sieves. or, In step S2, the slurry is prepared into porous ceramics, and the specific preparation method is as follows: After filtration, washing, and drying, a pore-forming agent is added at a ratio of 0.05 to 0.1 times the total mass of electrolytic manganese slag and antimony tailings. The mixture is then calcined at 600 to 900°C for 0.5 to 3 hours to obtain porous ceramics.

[0027] In the above scheme, two routes were specifically designed. In the route for preparing zeolite, dilution and aging can promote the slow condensation and rearrangement of aluminosilicate geopolymers, thereby forming a complete crystal form.

[0028] In the ceramic sintering process, with the aid of water glass, sintering can be completed at a lower temperature. At the same time, the lower temperature also helps to fix toxic substances such as antimony and arsenic in the crystal lattice, avoiding secondary pollution caused by high-temperature volatilization.

[0029] In addition, this application also includes the fluoride removal adsorbent prepared by the above preparation method.

[0030] The fluoride removal adsorbent prepared by the above method not only follows the green and environmentally friendly design concept by using industrial waste as raw material, which greatly reduces the production cost, but also provides excellent adsorption performance. It can take into account high adsorption capacity, rapid adsorption kinetics, low adsorption equilibrium concentration, good chemical stability and high safety.

[0031] In addition, this application also relates to the application of the above-mentioned composite defluorination adsorbent in the treatment of fluoride-containing wastewater, wherein the pH of the fluoride-containing wastewater is controlled at 5 to 10 during the adsorption process.

[0032] Overall, the adsorbents prepared by the above methods can be used in a wide range of pH environments and can adsorb fluoride ions in wastewater with high efficiency. They can also maintain a low leaching amount under strong alkalinity, which reduces the requirements for pretreatment in wastewater treatment and has good prospects for practical application.

[0033] In summary, this application provides a method for preparing molecular sieves or porous ceramics using electrolytic manganese slag and antimony tailings as raw materials through a hydrothermal reaction followed by further processing. By utilizing the oxidizing properties of manganese and the highly selective adsorption of antimony, the heavy metals inherent in the material are fixed, and the material exhibits improved fluoride ion adsorption performance. This method, while considering the recycling of industrial waste, prepares a fluoride ion adsorbent with high adsorption capacity, low adsorption equilibrium concentration, strong adsorption kinetics, and high safety and reliability. Detailed Implementation

[0034] The technical solutions in this application will be further described through the following specific embodiments.

[0035] In the following specific embodiments, the mass fraction composition of the selected electrolytic manganese slag (dry basis) is as follows: 33% silicon dioxide 6% manganese dioxide 7% ferric oxide Calcium oxide 11% SO3 30% 13% aluminum oxide Loss on ignition 5% The remaining components include trace amounts of magnesium oxide, potassium oxide, sodium oxide, phosphorus pentoxide, and other components.

[0036] The dry basis mass fraction composition of antimony tailings is as follows: 39% silicon dioxide 20% aluminum oxide 12% iron oxide Calcium oxide 5% Loss on ignition 8% The remaining components include trace amounts of magnesium oxide, calcium oxide, titanium oxide, manganese oxide, phosphorus pentoxide, and other components.

[0037] In addition, the antimony tailings contained 17,750 μg / g of arsenic and 4,591 μg / g of antimony.

[0038] The electrolytic manganese slag and antimony tailings were dried, ground, and passed through an 18-mesh sieve to obtain powder for later use.

[0039] For the following examples of zeolites and porous ceramics, the applicant designed the following experiments: Experiment 1: The specific surface area of ​​the adsorbent was determined by nitrogen adsorption-desorption using the BET method.

[0040] Experiment 2: Adsorbent was added to simulated wastewater containing fluoride ions at a dosage of 0.5 g / L. The simulated wastewater was prepared by dissolving sodium fluoride in water and adding an acetic acid buffer system (ion concentration 0.2 M) to adjust the pH to 9.0. The initial concentration of fluoride ions was 10 mg / L. After the adsorbent was added, the mixture was stirred at a constant temperature of 25°C. The residual fluoride ion concentration in the filtrate was measured using a fluoride ion selective electrode until the fluoride ion concentration no longer changed for 1 hour. The removal of fluoride ions could be calculated from the initial and final concentrations.

[0041] Experiment 3: Based on Experiment 2, the initial concentration of fluoride ions was set to 200 mg / L, and the adsorbent was added at a rate of 0.5 g / L. The temperature was kept constant, and the residual concentration of fluoride ions in the filtrate was measured by a fluoride ion selective electrode until the concentration of fluoride ions no longer changed for 1 hour. The saturated adsorption capacity of the adsorbent was calculated from the initial concentration and the final concentration.

[0042] Experiment 4, Toxicity Leaching Experiment: Based on Experiment 2, after treatment, the adsorbent was removed by filtration, and the arsenic and antimony content in the leachate was evaluated. Specifically, the ion concentration was determined by ICP-MS according to Appendix B of GB 5085.3-2007 "Identification Standard for Hazardous Waste - Leaching Toxicity Identification".

[0043] First, Example A series was set up, in which electrolytic manganese slag and antimony tailings were combined to prepare zeolite-type adsorbents.

[0044] Example A1, the specific preparation method is as follows: S1. Take electrolytic manganese slag and antimony tailings, mix them in a mass ratio of 1:4, and add them to a sodium hydroxide solution with a molar concentration of 0.6 g / mL. Adjust the pH to 11 with sodium hydroxide, then stir and heat to 80℃, react for 4 hours, and then cool to 20℃. Weigh out water glass with a modulus of 1.7 (the mass of water glass is 10% of the total mass of electrolytic manganese slag and antimony tailings), and dilute it with deionized water to a density of 1.25 g / cm³. 3 Add it to the cooled system and set aside.

[0045] S2. In the above system, deionized water is added at three times the initial mass of electrolytic manganese slag and antimony tailings. After stirring for 5 minutes, the mixture is allowed to stand at 20°C for 18 hours. Then, it is filtered, washed with deionized water until the pH value is not higher than 9, and then vacuum dried at 105°C for 12 hours to obtain the zeolite molecular sieve composite defluorination adsorbent.

[0046] Based on the preparation example A1, the mass ratio of electrolytic manganese slag and antimony tailings was adjusted to obtain the examples shown in Table 1.

[0047] In addition, regarding the specific process of adding water glass, based on Example A1, different water glass selections and dosages were adjusted to obtain the specific examples shown in Table 2.

[0048] The above scheme demonstrates the feasibility of preparing zeolite adsorbent by adding water glass system after hot water hydrolysis of electrolytic manganese slag and antimony tailings. Overall, it can effectively adsorb fluoride ions in fluoride-containing wastewater, has a high overall capacity, and has a good adsorption balance effect on low concentrations of fluoride ions. At the same time, it can also better control the leaching of toxic components in antimony tailings.

[0049] In Examples A1 to A6, the ratios of different electrolytic manganese slag and antimony tailings were measured. It was found that the optimal ratio of electrolytic manganese slag to antimony tailings was between 1:2 and 6. Exceeding this range led to a decrease in the specific surface area and saturated adsorption capacity of the system. Furthermore, higher antimony tailings content resulted in a significant increase in the leaching of antimony and arsenic. Conversely, excessively low antimony tailings content reduced the number of active sites in the system, leading not only to a decrease in saturated adsorption capacity but also a significant impact on the removal rate of fluoride ions from low-concentration fluoride-containing wastewater.

[0050] In the embodiments listed in Table 2, the addition conditions and selection of water glass were adjusted. It can be seen that the addition of water glass generally had a more favorable effect on the specific surface area of ​​the system. Generally, the addition of water glass with a modulus in the range of 2.5–3.0 improved the specific surface area of ​​the system and also significantly inhibited the dissolution of arsenic and antimony. However, when the addition amount exceeded 15%, both the specific surface area and saturated adsorption performance showed a significant downward trend, and it was more likely to excessively cover the antimony active sites, leading to a significant weakening of its adsorption performance at low concentrations. Furthermore, among water glass with different moduli, water glass with lower moduli contained excessive sodium oxide, which adversely affected the strength, specific surface area, and pore structure of the system during aging. Although the specific surface area of ​​the system did not decrease significantly, the adsorption performance for fluoride ions was significantly reduced at low concentrations.

[0051] Furthermore, in Example A23, the lack of dilution of the water glass led to a certain degree of self-polymerization in the system, and the resulting microparticles easily clogged the pores, resulting in a decrease in specific surface area and a significant reduction in saturated adsorption capacity. In Example A24, adding water glass too early caused silica in the system to more easily affect the crystal structure of the system, and the addition of water glass led to excessive silicon participation in the zeolite formation process, ultimately resulting in unsatisfactory overall adsorption performance.

[0052] Example B series, in contrast to Example A1, involves the preparation of porous ceramics using electrolytic manganese slag and antimony tailings under the action of a pore-forming agent. To verify the ratio of electrolytic manganese slag and antimony tailings and the influence of water glass in the system, the applicant kept the selection and dosage of the pore-forming agent constant. However, it should be understood that in actual working conditions, the applicant can add different types and amounts of pore-forming agents according to the sintering and pressing process of the ceramics and the actual requirements for adsorption performance.

[0053] Preparation of Example B1: The specific preparation steps are as follows: S1. Take electrolytic manganese slag and antimony tailings, mix them in a mass ratio of 1:6, and add them to a sodium hydroxide solution of a specific molar concentration at a solid-liquid ratio of 0.5 g / mL. Adjust the pH to 11 with sodium hydroxide, then stir and heat to 80℃, react for 4 hours, and then cool to 20℃. Weigh out water glass with a modulus of 1.7 (the mass of water glass is 15% of the total mass of electrolytic manganese slag and antimony tailings), and dilute it with deionized water to a density of 1.25 g / cm³. 3 Add it to the cooled system and set aside.

[0054] S2. After the above slurry is filtered, the filter cake is washed with deionized water until neutral, then dried at 105±5℃ for 12 hours, ground into powder, and starch is added as a pore-forming agent at a mass ratio of 0.08 times the initial total mass of electrolytic manganese slag and antimony tailings. Then it is pressed into ceramic green bodies, heated to 850℃ in a muffle furnace at a heating rate of 5℃ / min, and calcined for 2 hours to obtain porous ceramic raw materials.

[0055] S3. After sintering, the porous ceramic raw material is naturally cooled to room temperature. The mold is made of 5mm×5mm×5mm cube particles. The particles are immersed in 0.5M sodium hydroxide solution and re-etched at 50℃ for 20min. Then, the material is filtered, and the filter residue is washed with deionized water until neutral. The material is dried at 105±5℃ for 12 hours to obtain the porous ceramic adsorbent.

[0056] Based on the preparation example B1, the mass ratio of electrolytic manganese slag and antimony tailings was adjusted to obtain the examples shown in Table 3.

[0057] In addition, regarding the specific process of adding water glass, based on Example B1, different water glass selections and dosages were adjusted to obtain the specific examples shown in Table 4.

[0058] In addition, the re-etching steps were adjusted based on Example B1, as shown in Table 5.

[0059] Based on the experimental data above, it can be seen that, similar to molecular sieves, porous ceramics prepared by electrolytic manganese slag and antimony tailings also have good adsorption performance. Overall, porous ceramics have a lower saturated adsorption capacity and a smaller specific surface area compared to zeolite structures, but the removal rate at low concentrations is less affected. After re-etching, they can still maintain good adsorption performance and low arsenic and antimony leaching levels.

[0060] By comparing examples B1 to B6, it can be seen that for porous ceramic systems, the mass ratio of electrolytic manganese slag to antimony tailings should be controlled at 1:6 to 1:8. If the content of antimony tailings is too low, the overall pore collapse will occur, resulting in a certain reduction in specific surface area.

[0061] In the experiment of adjusting the water glass, it can be seen that Examples B23 and B24 are generally similar to Examples A23 and A24 in terms of properties. However, through experiments, it was found that for porous ceramic systems, water glass with a lower modulus should be used. A modulus exceeding 2.0 will lead to an increase in the dissolution of arsenic and antimony in the system to a certain extent, and will have a certain adverse effect on the final sintering process, resulting in a decrease in overall adsorption performance. At the same time, a larger amount of water glass can be added to this system. If the amount added is too low, there will also be a small amount of arsenic and antimony ion dissolution.

[0062] In addition, in Examples B25 to B28, it can be seen that re-etching can improve the overall adsorption performance and increase the specific surface area. Compared with Example B28, Examples B1, B25 and B26 all show significant improvement in adsorption performance. However, excessive etching can also lead to higher leaching of arsenic and antimony, and can also have an adverse effect on the active sites in the pores, thus weakening the adsorption performance at low concentrations.

[0063] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing an adsorbent for the synergistic resource-based treatment of fluoride-containing wastewater, characterized in that, Includes the following steps: S1. Electrolytic manganese slag and antimony tailings are subjected to an alkaline environment and their crystalline phases are destroyed through a hydrothermal reaction to obtain a slurry. S2. Prepare an adsorbent from the slurry according to at least one of step a or step b: a. After aging, the slurry is prepared into zeolite molecular sieves; b. Add a pore-forming agent to the slurry, and after sintering, prepare porous ceramics; In step S1, the mass ratio of electrolytic manganese slag to antimony tailings is 1:1 to 1:

10.

2. The method for preparing an adsorbent for synergistic resource recovery treatment of fluoride-containing wastewater according to claim 1, characterized in that, In step S1, water glass is also added. The amount of water glass added, calculated as silicon dioxide, is 5% to 20% of the total mass of electrolytic manganese slag and antimony tailings.

3. The method for preparing an adsorbent for synergistic resource recovery treatment of fluoride-containing wastewater according to claim 2, characterized in that, In step S2, the slurry is prepared into a zeolite molecular sieve, and in step S1, the modulus of the water glass is 2.5 to 3.0; or, In step S2, the slurry is prepared into a porous ceramic, and in step S1, the water glass modulus is 1.5 to 2.

0.

4. The method for preparing an adsorbent for synergistic resource recovery treatment of fluoride-containing wastewater according to claim 3, characterized in that, In step S2, the slurry is prepared into a zeolite molecular sieve, and the mass ratio of electrolytic manganese slag to antimony tailings is 1:2 to 1:6, and the amount of water glass added is 5% to 10% of the total mass of electrolytic manganese slag and antimony tailings. or, In step S2, the slurry is prepared into porous ceramics, and in step S1, the mass ratio of electrolytic manganese slag to antimony tailings is 1:6 to 1:8, and the amount of water glass added is 15% to 20% of the total mass of electrolytic manganese slag and antimony tailings.

5. The method for preparing an adsorbent for synergistic resource recovery treatment of fluoride-containing wastewater according to claim 3, characterized in that, In step S2, the slurry is prepared into a porous ceramic. After preparation, the porous ceramic is re-etched with an alkaline solution. The molar concentration of the alkaline solution is 0.1-1 M (calculated as hydroxide), the etching temperature is 40-60°C, and the etching time is 10-30 min.

6. The method for preparing an adsorbent for synergistic resource recovery treatment of fluoride-containing wastewater according to claim 2, characterized in that, The water glass was diluted with water to a density of 1.2–1.3 g / cm³ before being added. 3 ; And / or, In step S1, the electrolytic manganese slag, antimony tailings and alkaline solution are first hydrated. After the reaction is completed, the temperature is lowered to no higher than 40°C, and then water glass is added. Then step S2 is carried out directly.

7. The method for preparing an adsorbent for synergistic resource recovery treatment of fluoride-containing wastewater according to claim 6, characterized in that, In step S1, the pH value is 10–12, and / or, In step S1, the hydrothermal reaction temperature is 70–100°C, and / or, In step S1, the reaction time is 2–6 hours, and / or, In step S1, the solid-liquid ratio of electrolytic manganese slag and antimony tailings to alkaline solution is 0.2–1 g / mL.

8. The method for preparing an adsorbent for synergistic resource recovery treatment of fluoride-containing wastewater according to claim 1, characterized in that, In step S2, the slurry is prepared into a zeolite molecular sieve, and the specific preparation method is as follows: The slurry was cooled to 10–40°C, and then 1–5 times the mass of the initial electrolytic manganese slag and antimony tailings were added to deionized water. The mixture was allowed to stand and age for 12–24 hours, and then filtered, washed and dried to obtain molecular sieves. or, In step S2, the slurry is prepared into porous ceramics, and the specific preparation method is as follows: After filtration, washing, and drying, a pore-forming agent is added at a ratio of 0.05 to 0.1 times the total mass of electrolytic manganese slag and antimony tailings. The mixture is then calcined at 600 to 900°C for 0.5 to 3 hours to obtain porous ceramics.

9. The composite defluorination adsorbent prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the composite defluoridation adsorbent prepared by the preparation method according to any one of claims 1 to 8, or the composite defluoridation adsorbent according to claim 9, in the treatment of fluoride-containing wastewater, characterized in that, During the adsorption process, the pH of the fluoride-containing wastewater is controlled at 5–10.

Images