Efficient defluorination method suitable for semiconductor fluorine-containing wastewater

Abstract

The invention discloses an efficient defluorination method suitable for semiconductor fluorine-containing wastewater, belongs to the technical field of wastewater purification, and is used for solving the technical problem that the fluorine removal rate and impurity ion removal rate of a semiconductor fluorine-containing wastewater defluorination method in the prior art need to be further improved. Aiming at the semiconductor fluorine-containing wastewater, zinc-iron oxidized composite microspheres are sequentially adopted to carry out primary fluorine removal pretreatment, a zirconium-zinc phosphonic acid hybrid material is utilized to carry out deep complex breaking adsorption on complex fluorine and heavy metals, and finally, a calcium-aluminum-zinc fluorapatite solid solution is utilized to realize crystallization and solidification treatment on residual fluorine and multiple metals. A continuous treatment process from reduction, complex breaking to solidification is constructed, the process shows a relatively high removal effect on fluoride, total phosphorus and metal ions such as aluminum, copper and iron, the effluent quality is stable, the treatment load is large, and the process is suitable for deep purification treatment of semiconductor fluorine-containing wastewater with complex components and strong volatility.

Description

Technical Field

[0001] This invention relates to the field of wastewater purification technology, and specifically to a highly efficient defluorination method suitable for semiconductor fluoride-containing wastewater. Background Technology

[0002] Semiconductor wastewater contains high concentrations of fluoride with diverse complex forms, accompanied by various impurity ions such as aluminum, copper, iron, and total phosphorus. This causes the defluorination process to be affected by both competitive reactions and complex stability. Traditional calcium salt precipitation and aluminum and iron salt co-precipitation are mainly used to remove free fluoride. However, with the increase in the use of complexing agents, the proportion of complexed fluoride increases, which reduces the efficiency of conventional precipitation reactions. To improve the defluorination effect, research has gradually introduced methods such as complex breaking, enhanced nucleation, adsorption materials, and crystal fixation to deal with the multiple forms of fluoride and improve solid-liquid separation. At the same time, the interference of impurity ions has prompted research to shift from single defluorination to the synergistic control of fluoride, metal ions, and total phosphorus, driving the development of treatment technologies towards multi-stage and combined approaches.

[0003] Current treatment processes have limited efficiency under high concentrations and complexed fluoride conditions, often requiring large amounts of reagents to form precipitates. However, the particles are small and easily carry impurities, making solid-liquid separation difficult and resulting in unstable fluoride concentrations in the effluent. Ions such as aluminum, copper, and iron in the wastewater compete with the precipitant or form new complexes, hindering the precipitation process. Total phosphorus interferes with crystal growth, weakening the precipitate structure and filtration performance. Furthermore, single technologies such as adsorption or complex breaking are insufficient to simultaneously address the complex system of multiple forms of fluoride and the coexistence of multiple ions, only improving the removal efficiency of some pollutants. Moreover, due to discontinuous process connections and insufficient pollutant conversion, deep defluorination and multi-component synergistic removal remain limited.

[0004] To address this technical deficiency, a solution is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a highly efficient defluorination method for semiconductor fluoride-containing wastewater, which solves the technical problem that the fluoride removal rate and impurity ion removal rate of existing semiconductor fluoride-containing wastewater defluorination methods need to be further improved.

[0006] The objective of this invention can be achieved through the following technical solution: a highly efficient defluorination method suitable for semiconductor fluoride-containing wastewater, comprising the following steps: S1. The semiconductor fluorine-containing wastewater is introduced into the primary reaction tank and stirred. After adding zinc-iron oxide composite microspheres, the pH of the reaction system is adjusted to 5-6. Then, the temperature of the primary reaction tank is controlled at 20-30℃ and stirred for 20-30 minutes. Subsequently, the reaction liquid is sent to the primary sedimentation tank for solid-liquid separation, and the effluent is collected to obtain the primary fluoride-removing effluent. The reaction principle for preparing primary defluoridated water is as follows: Zinc-iron oxide composite microspheres have a porous structure and abundant active sites of metal oxides. Their surface carries a positive charge in a weakly acidic to weakly neutral environment, which can form strong electrostatic adsorption and surface complexation with fluoride ions in wastewater. At the same time, the iron oxide can undergo in-situ hydrolysis to generate hydroxyl iron species with strong affinity for fluoride, so that fluoride ions are fixed on the material surface in the form of inner-layer complexation. In addition, after zinc ions are partially dissolved and released on the surface, they can form low-solubility fluoride zinc precipitate with fluoride ions, thereby further reducing the effective concentration of fluoride in the solution, thus obtaining primary fluoride-reducing effluent.

[0007] S2. Use zirconium zinc phosphonic acid hybrid material to perform secondary defluorination on the primary defluorination effluent to obtain effluent with deep removal of complexed fluoride. The reaction principle for preparing complexed fluoride for deep removal of effluent is as follows: The internal structure of the effluent with deep fluoride removal via complexation consists of a three-dimensional hybrid network composed of phosphonic acid groups, polyamine structures, and multi-metal centers. It possesses numerous PO, N, and metal-oxygen bond bridge structures that can participate in coordination. This network can break down and recapture stable complexed fluoride present in wastewater in the form of aluminum-fluoride complexes and silicon-fluoride complexes. When the complexed fluoride enters the material's pores, coordination substitution occurs between the phosphonic acid groups and fluoride. Zirconium ions provide strong Lewis acid sites, promoting the dissociation of the complexes. Simultaneously, zinc centers form inner-layer coordination with fluoride, thereby achieving deep fixation of recalcitrant complexed fluoride. The synergy of multiple coordination, adsorption, and weak exchange interactions enables the material to achieve complete capture of complexed fluoride under relatively mild conditions, generating stable bound fluoride and achieving deep defluorination, resulting in effluent with deep fluoride removal via complexation.

[0008] S3. The effluent from the deep removal of complexed fluoride is introduced into a three-stage crystallization reaction tank and stirred. Calcium aluminum zinc fluoroapatite solid solution is added to the three-stage crystallization reaction tank, along with calcium chloride and disodium hydrogen phosphate. The pH of the reaction system is adjusted to 7.5-8.5. The temperature of the three-stage crystallization reaction tank is controlled at 20-30℃ and stirred for 40-60 minutes. Then, it is sent to a filtration unit for solid-liquid separation to obtain deeply defluorinated water.

[0009] The reaction principle for preparing deeply defluorinated water is as follows: The calcium aluminum zinc fluorapatite solid solution has a stable hexagonal crystal structure, and its surface exposes Ca... 2+ Site and PO4 3- Tetrahedrons provide channels for fluoride ions to enter the crystal lattice. When complexed fluoride is removed from the effluent and enters the system, the fluoride ions in the solution, together with the added calcium and phosphorus sources, drive the reassembly of Ca, PF, and fluoride, causing fluoride to preferentially substitute for hydroxyl groups or react with Ca. 2+Stable Ca-F bonds are formed, which promotes the directional growth of the system towards "fluorapatite crystals". At the same time, aluminum and zinc in the solid solution can regulate the lattice charge balance and promote heterogeneous nucleation on the crystal surface, making the precipitated crystals more compact and stable. Through the synergistic effect of multiple mechanisms such as lattice substitution, heterogeneous nucleation and crystal solidification, the residual free fluoride and a small amount of complexed fluoride in the solution are fixed in the insoluble crystals, realizing terminal deep defluorination, and thus obtaining deep defluorinated water.

[0010] Furthermore, in step S1, the ratio of the amount of semiconductor fluoride-containing wastewater to zinc-iron oxide composite microspheres is 1L:300-500mg, wherein the fluoride content of the semiconductor fluoride-containing wastewater is 1000-1200mg / L. Further, in step S2, the secondary defluorination includes: passing the primary defluorinated effluent through a fixed-bed adsorption column packed with zirconium zinc phosphonic acid hybrid material at a flow rate of 4-6 BV / h, with an empty bed contact time of 20-30 min, adjusting the influent pH to 6.0-7.0, maintaining the operating temperature at 25-35℃, collecting the effluent to obtain effluent with deep removal of complexed fluoride, and using the first occurrence of a total fluoride concentration of 8 mg / L in the adsorption column effluent as the adsorption breakthrough criterion, stopping the operation and replacing the zirconium zinc phosphonic acid hybrid material; Furthermore, in step S3, the ratio of the amount of complexed fluoride deep-removed effluent to the calcium aluminum zinc fluoroapatite solid solution is 1L:100-150mg, wherein calcium chloride and disodium hydrogen phosphate are added as needed to make the calcium-phosphorus molar ratio 1.67.

[0011] Furthermore, the zinc-iron oxide composite microspheres are prepared by the following method: A1. Add magnesium hydroxide and deionized water to the reaction vessel and stir. After mixing evenly, introduce carbon dioxide gas to control the pH of the reaction system to 8.5-9.5. Then heat the reaction vessel to 30-40℃ and continuously introduce carbon dioxide. Keep the reaction at this temperature for 60-90 minutes. Post-processing yields porous alkaline magnesium carbonate microspheres. A2. Porous alkaline magnesium carbonate microspheres, 0.2 mol / L ferrous sulfate aqueous solution, 0.2 mol / L zinc sulfate aqueous solution, and deionized water are added to a reaction vessel and stirred. Under stirring conditions, saturated sodium hydroxide aqueous solution is added to adjust the pH of the reaction system to 8.0-9.0, and air is introduced. The reaction vessel is then heated to 30-35℃ and kept at this temperature for 40-60 min. The reaction solution is then transferred to a closed hydrothermal reaction vessel, and the hydrothermal reaction vessel is heated to 120-160℃ and kept at this temperature with stirring for 4-6 h. The zinc-iron oxide composite microspheres are obtained after post-treatment.

[0012] The reaction principle for preparing zinc-iron oxide composite microspheres is as follows: First, magnesium hydroxide undergoes a carbonation reaction under the action of carbon dioxide, generating a porous magnesium carbonate structure with a high specific surface area and weak alkaline buffering capacity, providing a stable framework for subsequent loading of metal oxides. Subsequently, iron and zinc ions undergo simultaneous hydrolysis and deposition in an alkaline environment, generating well-dispersed multimetallic hydroxides. With the participation of oxygen, ferrous ions are transformed into ferrooxy hydroxylates and their oxidation states. With the help of hydrothermal conditions, the multimetallic components further crystallize and solidify on the surface of magnesium carbonate, ultimately forming a stable composite structure composed of iron oxide, zinc oxide, and a magnesium-based support, thus preparing zinc-iron oxide composite microspheres.

[0013] Further, in step A1, the ratio of magnesium hydroxide to deionized water is 1-2 g: 10 mL. The post-treatment includes: stopping the carbon dioxide flow after the reaction is completed, filtering the reaction liquid after the reaction vessel has cooled naturally to room temperature, collecting the filter cake, washing the filter cake with deionized water 3-5 times, and then transferring the filter cake to a drying oven at 60°C and vacuum drying it to constant weight to obtain porous alkaline magnesium carbonate microspheres. Further, in step A2, the ratio of the porous alkaline magnesium carbonate microspheres, 0.2 mol / L ferrous sulfate aqueous solution, 0.2 mol / L zinc sulfate aqueous solution, and deionized water is 3-5 g: 60-80 mL: 60-80 mL: 100-120 mL, wherein the air flow rate is 0.8-1.0 L / min. The post-treatment includes: after the reaction is completed, the reaction solution is filtered after the reaction vessel temperature has naturally cooled to room temperature, the filter cake is collected, the filter cake is washed with deionized water 3-5 times, and then the filter cake is transferred to a drying oven at 60°C and vacuum dried to constant weight to obtain zinc-iron oxide composite microspheres.

[0014] Furthermore, the zirconium zinc phosphonate hybrid material is prepared by the following method: B1. Add aminotrimethylenephosphonic acid, 37wt% formaldehyde aqueous solution, ethylenediamine, deionized water and anhydrous ethanol to a reaction vessel and stir. After purging with nitrogen, adjust the pH of the reaction system to 3-4 with acetic acid. Then heat the reaction vessel to 60-70℃ and stir for 120-150 min. Post-treatment yields polyphosphonic acid polyamine gel. B2. Add polyphosphonic acid polyamine gel, 0.2 mol / L zirconium oxychloride aqueous solution, 0.2 mol / L zinc nitrate aqueous solution, deionized water and anhydrous ethanol to a reaction vessel and stir. Purge with nitrogen and adjust the pH of the reaction system to 2-3 with acetic acid. Then raise the temperature of the reaction vessel to 40-60℃ and keep it at this temperature for 2-4 hours. Post-processing yields zirconium zinc phosphonic acid hybrid material.

[0015] The reaction principle for preparing zirconium zinc phosphonate hybrid materials is as follows: The phosphonic acid group of aminotrimethylenephosphonic acid and the amino group of ethylenediamine undergo Mannich-type condensation under the action of formaldehyde, constructing an organic gel framework rich in polydentate coordination sites. This provides a stable framework for subsequent metal ion anchoring. When zirconium ions enter the system, they readily undergo hydrolysis and condense with the P-OH groups of phosphonic acid to form stable Zr-OP bonds, thereby enhancing the cross-linking of the gel framework with inorganic nodes. Simultaneously, zinc ions further enrich the metal center structure of the material by coordinating with the oxygen atoms of phosphonic acid and the nitrogen atoms of amino groups, creating a multi-metal synergistic complex coordination environment within the framework. The above-mentioned "organic condensation-metal coordination-inorganic condensation" process jointly promotes the formation of a three-dimensional hybrid porous network structure, thus endowing it with good stability and multifunctional reactivity, ultimately preparing a zirconium-zinc phosphonic acid hybrid material.

[0016] Further, in step B1, the ratio of aminotrimethylenephosphonic acid, 37wt% formaldehyde aqueous solution, ethylenediamine, deionized water and anhydrous ethanol is 2-3g:4-6g:1-2g:20mL:80mL. The post-treatment includes: after the reaction is completed, the nitrogen gas is turned off, and after the temperature of the reaction vessel drops to room temperature, the reaction system is filtered to collect the gel-like solid. After washing with anhydrous ethanol and deionized water 3-5 times, the gel is transferred to a drying oven at 70℃ and vacuum dried to constant weight to obtain polyphosphonic acid polyamine gel. Further, in step B2, the ratio of the polyphosphonic acid polyamine gel, 0.2 mol / L zirconium oxychloride aqueous solution, 0.2 mol / L zinc nitrate aqueous solution, deionized water and anhydrous ethanol is 1 g: 20-30 mL: 20-30 mL: 20 mL: 80 mL. The post-processing includes: after the reaction is completed, the reaction solution is filtered after the reaction vessel temperature is naturally cooled to room temperature, the filter cake is collected, the filter cake is washed with deionized water 3-5 times, and then the filter cake is transferred to a drying oven at 60°C and vacuum dried to constant weight to obtain zirconium zinc phosphonic acid hybrid material.

[0017] Furthermore, the calcium aluminum zinc fluoroapatite solid solution is prepared by the following method: C1. Add 0.3 mol / L calcium chloride aqueous solution, 0.2 mol / L aluminum chloride aqueous solution, 0.1 mol / L zinc chloride aqueous solution and the calculated amount of disodium hydrogen phosphate to the reaction vessel and stir. Adjust the pH of the reaction system to 10.0-10.5 with saturated sodium hydroxide aqueous solution, control the temperature of the reaction vessel at 25-35℃, keep it at the temperature and stir for 60-80 min, and then process to obtain calcium aluminum zinc phosphate layered solid. C2. After mixing and grinding the layered solid calcium aluminum zinc phosphate and sodium fluorosilicate into a reaction vessel, nitrogen gas is introduced for protection, and the reaction vessel is heated to 200-250℃ and kept at this temperature for 4-6 hours. The calcium aluminum zinc fluoroapatite solid solution is then obtained through post-treatment.

[0018] The reaction principle for preparing calcium aluminum zinc fluorapatite solid solution is as follows: First, calcium, aluminum, and zinc ions react with phosphate ions under strongly alkaline conditions to form layered polymetallic phosphates. The introduction of aluminum and zinc acts as lattice modifiers, improving the stability of the precipitate structure and providing heterovalent metal sites that can enter the lattice. Subsequently, under heating and inert protection, fluoride ions released by sodium fluorosilicate gradually replace hydroxyl groups and some hydrogen phosphate ions in the layered structure, causing lattice rearrangement and anion orientation substitution, ultimately transforming the system into a Ca2+ polymetallic phosphate. 2+ -PO4 3- -F - The typical hexagonal fluorapatite structure is formed, in which aluminum and zinc form a stable solid solution, which optimizes the surface electrical properties and reactivity of the crystal, and finally prepares a calcium aluminum zinc fluorapatite solid solution.

[0019] Further, in step C1, the ratio of the 0.3 mol / L calcium chloride aqueous solution, 0.2 mol / L aluminum chloride aqueous solution, and 0.1 mol / L zinc chloride aqueous solution is 4-6 mL: 2-3 mL: 1-2 mL, wherein the amount of disodium hydrogen phosphate added is 0.6 times the molar amount of calcium ions in the reaction system. The post-processing includes: after the reaction is completed, after the reaction vessel temperature is naturally cooled to room temperature, the reaction solution is filtered, the filter cake is collected, the filter cake is washed with deionized water 3-5 times, and then the filter cake is transferred to a drying oven at 60°C and vacuum dried to constant weight to obtain a layered solid of calcium aluminum zinc phosphate. Further, in step C2, the ratio of the calcium aluminum zinc phosphate layered solid to sodium fluorosilicate is 10g:1-2g. The post-treatment includes: stopping heating and nitrogen gas introduction after the reaction is completed, allowing the reaction apparatus to cool naturally to room temperature, taking out the solid, washing it 3-5 times with anhydrous ethanol and deionized water, and then transferring the solid to a drying oven at 80°C for vacuum drying to constant weight to obtain calcium aluminum zinc fluoroapatite solid solution.

[0020] The present invention has the following beneficial effects: 1. This invention establishes a multi-stage defluorination system consisting of zinc-iron oxide composite microspheres, zirconium-zinc phosphonic acid hybrid materials, and calcium-aluminum-zinc fluoroapatite solid solution. These materials are mechanistically interconnected. First, the zinc-iron oxide composite microspheres, with their porous structure and the active surfaces of ferric oxide hydroxylates and zinc oxide, can rapidly adsorb free fluoride under weakly acidic conditions and locally form fluoride precipitates, causing a rapid decrease in the initial fluoride concentration. Second, the zirconium-zinc phosphonic acid hybrid materials, relying on a multidentate coordination framework composed of phosphonic acid groups, amino groups, and metal centers, can disrupt the stable complex structures of aluminum-fluorine and silicon-fluorine compounds, achieving deep capture of complexed fluoride through coordination substitution and metal-assisted bond breaking. Finally, the calcium-aluminum-zinc fluoroapatite solid solution provides a lattice fixation path, allowing residual fluoride to participate in the directional growth of the Ca-PF lattice and be stably sealed within the solid solution structure. This "primary adsorption-complex breaking capture-lattice solidification" defluorination chain ensures a long-term stable low fluoride content in the effluent, with overall performance significantly superior to traditional single-stage treatment methods.

[0021] 2. This invention also forms a layered synergistic system in dephosphorization. First, the surface of the zinc-iron oxide composite microspheres is rich in ferric oxide hydroxylates, which can react with PO4. 3- The process involves internal complexation and precipitation reactions, achieving initial reduction of dissolved phosphorus. The addition of zinc oxide enhances the positive charge on the material surface, enabling it to maintain its adsorption capacity for phosphate ions over a wide pH range. Subsequently, the numerous phosphonic acid groups and metal nodes distributed in the zirconium-zinc phosphonic acid hybrid material can further fix residual phosphorus through metal bridging, hydrogen bonding, and weak exchange, exhibiting good capture effects on weakly complexed phosphorus and some difficult-to-treat phosphorus forms. Finally, during the growth of Ca-P crystals, the calcium aluminum zinc fluoroapatite solid solution solidifies phosphorus into the crystal structure. The solid solution of aluminum and zinc makes the crystals more compact and stable, thereby achieving irreversible encapsulation. Ultimately, through the triple pathway of "adsorption-deep capture-lattice solidification," the total phosphorus in the effluent remains stable and meets the standards, with a significantly better phosphorus removal effect than traditional iron and aluminum salt precipitation processes.

[0022] 3. The zinc-iron oxide composite microspheres prepared by this invention have a surface rich in ferric oxide hydroxylates and zinc oxide active sites, enabling them to rapidly adsorb Al under weakly acidic conditions. 3+ Fe 2+ / Fe 3+ and Cu 2+ Furthermore, initial reduction is achieved through mechanisms such as hydroxide co-precipitation and surface complexation, exhibiting a particularly high affinity for iron ions. Secondly, the multidentate coordination network constructed within the zirconium-zinc phosphonic acid hybrid material contains phosphonic acid groups, amino groups, and multi-metal centers, which can further immobilize difficult-to-treat metal ions, including Zr. 4+ The Lewis acid site can strongly capture Al 3+ And Zn 2+ And the oxygen atom of phosphonic acid is related to Cu 2+ Fe 3+The formation of inner-layer coordination allows for the deep removal of residual metal ions. Ultimately, the calcium-aluminum-zinc fluoroapatite solid solution is formed through Ca... 2+ Site and PO4 3- To construct a stable crystal lattice, aluminum, zinc, and some iron ions can be dissolved into the crystal structure during the crystallization process, while simultaneously promoting Cu... 2+ By using phosphate precipitation for synergistic fixation and achieving irreversible solidification at the terminal, the removal rates of aluminum, copper, and iron are significantly improved, which is significantly better than the traditional single iron salt or aluminum salt method. This provides an efficient and reliable technical approach for the treatment of multi-metal pollution in complex fluoride-containing wastewater. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 This embodiment provides a method for preparing zinc-iron oxide composite microspheres, including the following steps: Step I: Preparation of porous alkaline magnesium carbonate microspheres Weigh out 10.0g of magnesium hydroxide and 100.0mL of deionized water and add them to the reaction vessel. Stir until the mixture is homogeneous. Then, introduce carbon dioxide gas to control the pH of the reaction system to 8.5. Heat the reaction vessel to 30℃ and continue to introduce carbon dioxide. Keep the reaction vessel at this temperature for 60min. After the reaction is complete, stop introducing carbon dioxide. After the reaction vessel has cooled to room temperature, filter the reaction liquid and collect the filter cake. Wash the filter cake three times with deionized water. Then, transfer the filter cake to a drying oven at 60℃ and vacuum dry it to constant weight to obtain porous alkaline magnesium carbonate microspheres.

[0025] Step II: Preparation of zinc-iron oxide composite microspheres Weigh out 3.0 g of porous alkaline magnesium carbonate microspheres, 60.0 mL of 0.2 mol / L ferrous sulfate aqueous solution, 60.0 mL of 0.2 mol / L zinc sulfate aqueous solution, and 100.0 mL of deionized water and add them to the reaction vessel. Stir the mixture and add saturated sodium hydroxide aqueous solution to adjust the pH of the reaction system to 8.0. Then, introduce air at a flow rate of 0.8 L / min and heat the reaction vessel to 30 °C. After holding the reaction at this temperature for 40 min, transfer the reaction solution to a closed hydrothermal reaction vessel. Heat the hydrothermal reaction vessel to 120 °C and stir for 4 h. After the reaction is complete, allow the reaction vessel to cool naturally to room temperature and then filter the reaction solution. Collect the filter cake and wash it three times with deionized water. Then, transfer the filter cake to a drying oven at 60 °C and vacuum dry it to constant weight to obtain zinc-iron oxide composite microspheres.

[0026] Example 2 This embodiment provides a method for preparing zinc-iron oxide composite microspheres, including the following steps: Step I: Preparation of porous alkaline magnesium carbonate microspheres Weigh out 20.0g of magnesium hydroxide and 100.0mL of deionized water and add them to the reaction vessel. Stir until the mixture is homogeneous. Then, introduce carbon dioxide gas to control the pH of the reaction system to 9.5. Heat the reaction vessel to 40℃ and continue to introduce carbon dioxide. Keep the reaction at this temperature for 90min. After the reaction is complete, stop introducing carbon dioxide. After the reaction vessel has cooled to room temperature, filter the reaction liquid and collect the filter cake. Wash the filter cake 5 times with deionized water. Then, transfer the filter cake to a drying oven at 60℃ and vacuum dry it to constant weight to obtain porous alkaline magnesium carbonate microspheres.

[0027] Step II: Preparation of zinc-iron oxide composite microspheres Weigh out 5.0 g of porous alkaline magnesium carbonate microspheres, 80.0 mL of 0.2 mol / L ferrous sulfate aqueous solution, 80.0 mL of 0.2 mol / L zinc sulfate aqueous solution, and 120.0 mL of deionized water and add them to the reaction vessel. Stir the mixture and add saturated sodium hydroxide aqueous solution to adjust the pH of the reaction system to 9.0. Then, introduce air at a flow rate of 1.0 L / min and heat the reaction vessel to 35°C. After holding the reaction at this temperature for 60 min, transfer the reaction solution to a closed hydrothermal reaction vessel. Heat the hydrothermal reaction vessel to 160°C and stir for 6 h. After the reaction is complete, allow the reaction vessel to cool naturally to room temperature and then filter the reaction solution. Collect the filter cake and wash it 5 times with deionized water. Then, transfer the filter cake to a drying oven at 60°C and vacuum dry it to constant weight to obtain zinc-iron oxide composite microspheres.

[0028] Example 3 This embodiment provides a method for preparing zinc-iron oxide composite microspheres, including the following steps: Step I: Preparation of porous alkaline magnesium carbonate microspheres Weigh 16.0g of magnesium hydroxide and 100.0mL of deionized water and add them to the reaction vessel. Stir until the mixture is homogeneous. Then, introduce carbon dioxide gas to control the pH of the reaction system to 9.0. Heat the reaction vessel to 35℃ and continue to introduce carbon dioxide. Keep the reaction at this temperature for 75min. After the reaction is complete, stop introducing carbon dioxide. After the reaction vessel has cooled to room temperature, filter the reaction liquid and collect the filter cake. Wash the filter cake four times with deionized water. Then, transfer the filter cake to a drying oven at 60℃ and vacuum dry it to constant weight to obtain porous alkaline magnesium carbonate microspheres.

[0029] Step II: Preparation of zinc-iron oxide composite microspheres Weigh out 4.0 g of porous alkaline magnesium carbonate microspheres, 70.0 mL of 0.2 mol / L ferrous sulfate aqueous solution, 70.0 mL of 0.2 mol / L zinc sulfate aqueous solution, and 110.0 mL of deionized water and add them to the reaction vessel. Stir the mixture and add saturated sodium hydroxide aqueous solution to adjust the pH of the reaction system to 8.5. Then, introduce air at a flow rate of 0.9 L / min and heat the reaction vessel to 35 °C. After holding the reaction at this temperature for 50 min, transfer the reaction solution to a closed hydrothermal reaction vessel. Heat the hydrothermal reaction vessel to 140 °C and stir for 5 h. After the reaction is complete, allow the reaction vessel to cool naturally to room temperature and then filter the reaction solution. Collect the filter cake and wash it four times with deionized water. Then, transfer the filter cake to a drying oven at 60 °C and vacuum dry it to constant weight to obtain zinc-iron oxide composite microspheres.

[0030] Example 4 This embodiment provides a method for preparing a zirconium zinc phosphonic acid hybrid material, including the following steps: Step 1: Preparation of polyphosphonic acid polyamine gel Weigh out 20.0 g of aminotrimethylenephosphonic acid, 40.0 g of 37 wt% formaldehyde aqueous solution, 10.0 g of ethylenediamine, 200.0 mL of deionized water and 800.0 mL of anhydrous ethanol and add them to the reaction vessel. Stir and purge with nitrogen gas. Adjust the pH of the reaction system to 3 with acetic acid. Then heat the reaction vessel to 60 °C and stir for 120 min. After the reaction is complete, turn off the nitrogen gas. After the temperature of the reaction vessel drops to room temperature, filter the reaction system and collect the gel-like solid. Wash the gel three times with anhydrous ethanol and deionized water. Transfer the gel to a drying oven at 70 °C and vacuum dry to constant weight to obtain polyphosphonic acid polyamine gel.

[0031] Step 2: Preparation of zirconium zinc phosphonic acid hybrid materials Weigh out 10.0 g of polyphosphonic acid polyamine gel, 20.0 mL of 0.2 mol / L zirconium oxychloride aqueous solution, 20.0 mL of 0.2 mol / L zinc nitrate aqueous solution, 20.0 mL of deionized water and 80.0 mL of anhydrous ethanol and add them to the reaction vessel. Stir, purge with nitrogen gas and adjust the pH of the reaction system to 2 with acetic acid. Then raise the temperature of the reaction vessel to 40 °C and keep it at this temperature for 2 h with stirring. After the reaction is completed, let the temperature of the reaction vessel cool naturally to room temperature and filter the reaction solution. Collect the filter cake and wash the filter cake three times with deionized water. Then transfer the filter cake to a drying oven at 60 °C and vacuum dry it to constant weight to obtain zirconium zinc phosphonic acid hybrid material.

[0032] Example 5 This embodiment provides a method for preparing a zirconium zinc phosphonic acid hybrid material, including the following steps: Step 1: Preparation of polyphosphonic acid polyamine gel Weigh out 30.0 g of aminotrimethylenephosphonic acid, 60.0 g of 37 wt% formaldehyde aqueous solution, 20.0 g of ethylenediamine, 200.0 mL of deionized water and 800.0 mL of anhydrous ethanol and add them to the reaction vessel. Stir and purge with nitrogen. Adjust the pH of the reaction system to 4 with acetic acid. Then heat the reaction vessel to 70 °C and stir for 150 min. After the reaction is complete, turn off the nitrogen. After the temperature of the reaction vessel drops to room temperature, filter the reaction system and collect the gel-like solid. Wash the gel five times with anhydrous ethanol and deionized water. Transfer the gel to a drying oven at 70 °C and vacuum dry to constant weight to obtain polyphosphonic acid polyamine gel.

[0033] Step 2: Preparation of zirconium zinc phosphonic acid hybrid materials Weigh out 10.0 g of polyphosphonic acid polyamine gel, 30.0 mL of 0.2 mol / L zirconium oxychloride aqueous solution, 30.0 mL of 0.2 mol / L zinc nitrate aqueous solution, 20.0 mL of deionized water and 80.0 mL of anhydrous ethanol and add them to the reaction vessel. Stir, purge with nitrogen gas for protection and adjust the pH of the reaction system to 3 with acetic acid. Then raise the temperature of the reaction vessel to 60 °C and keep it at this temperature for 4 h with stirring. After the reaction is completed, let the temperature of the reaction vessel cool naturally to room temperature and filter the reaction solution. Collect the filter cake and wash the filter cake 5 times with deionized water. Then transfer the filter cake to a drying oven at 60 °C and vacuum dry it to constant weight to obtain zirconium zinc phosphonic acid hybrid material.

[0034] Example 6 This embodiment provides a method for preparing a zirconium zinc phosphonic acid hybrid material, including the following steps: Step 1: Preparation of polyphosphonic acid polyamine gel Weigh out 25.0 g of aminotrimethylenephosphonic acid, 50.0 g of 37 wt% formaldehyde aqueous solution, 16.0 g of ethylenediamine, 200.0 mL of deionized water, and 800.0 mL of anhydrous ethanol and add them to a reaction vessel. Stir the mixture and purge it with nitrogen. Adjust the pH of the reaction system to 3 with acetic acid. Then heat the reaction vessel to 60 °C and stir for 120 min. After the reaction is complete, turn off the nitrogen gas. After the temperature of the reaction vessel drops to room temperature, filter the reaction system and collect the gel-like solid. Wash the solid four times with anhydrous ethanol and deionized water. Transfer the gel to a drying oven at 70 °C and vacuum dry it to constant weight to obtain polyphosphonic acid polyamine gel.

[0035] Step 2: Preparation of zirconium zinc phosphonic acid hybrid materials Weigh out 10.0 g of polyphosphonic acid polyamine gel, 25.0 mL of 0.2 mol / L zirconium oxychloride aqueous solution, 25.0 mL of 0.2 mol / L zinc nitrate aqueous solution, 20.0 mL of deionized water and 80.0 mL of anhydrous ethanol and add them to the reaction vessel. Stir, purge with nitrogen gas and adjust the pH of the reaction system to 2 with acetic acid. Then raise the temperature of the reaction vessel to 60 °C and keep it at this temperature for 4 h with stirring. After the reaction is completed, let the temperature of the reaction vessel cool naturally to room temperature and filter the reaction solution. Collect the filter cake and wash it 4 times with deionized water. Then transfer the filter cake to a drying oven at 60 °C and vacuum dry it to constant weight to obtain zirconium zinc phosphonic acid hybrid material.

[0036] Example 7 This embodiment provides a method for preparing an aluminum zinc fluoroapatite solid solution, including the following steps: Step ①: Preparation of calcium, aluminum, and zinc phosphate layered solids Weigh out 40.0 mL of 0.3 mol / L calcium chloride aqueous solution, 20.0 mL of 0.2 mol / L aluminum chloride aqueous solution, 10.0 mL of 0.1 mol / L zinc chloride aqueous solution, and disodium hydrogen phosphate (0.6 times the molar amount of calcium ions in the reaction system) and add them to the reaction vessel. Stir the mixture, adjust the pH of the reaction system to 10.0 using saturated sodium hydroxide aqueous solution, and control the temperature of the reaction vessel at 25℃. Keep the mixture warm and stir for 60 min. After the reaction is complete, allow the reaction vessel to cool naturally to room temperature, filter the reaction solution, collect the filter cake, wash the filter cake three times with deionized water, and then transfer the filter cake to a drying oven at 60℃ and vacuum dry it to constant weight to obtain a layered solid of calcium, aluminum, and zinc phosphate.

[0037] Step 2: Preparation of calcium aluminum zinc fluorapatite solid solution Weigh out 10.0g of calcium aluminum zinc phosphate layered solid and 1.0g of sodium fluorosilicate, add them to the reaction vessel, mix and grind them evenly, then introduce nitrogen protection and heat the reaction vessel to 200℃, keep the temperature for 4h. After the reaction is completed, stop heating and nitrogen introduction, and let the reaction device cool naturally to room temperature. Take out the solid, wash it 3 times with anhydrous ethanol and deionized water, and then transfer the solid to a drying oven at 80℃ and vacuum dry it to constant weight to obtain calcium aluminum zinc fluoroapatite solid solution.

[0038] Example 8 This embodiment provides a method for preparing an aluminum zinc fluoroapatite solid solution, including the following steps: Step ①: Preparation of calcium, aluminum, and zinc phosphate layered solids Weigh out 60.0 mL of 0.3 mol / L calcium chloride aqueous solution, 30.0 mL of 0.2 mol / L aluminum chloride aqueous solution, 20.0 mL of 0.1 mol / L zinc chloride aqueous solution, and disodium hydrogen phosphate (0.6 times the molar amount of calcium ions in the reaction system) and add them to the reaction vessel. Stir the mixture, adjust the pH of the reaction system to 10.5 using saturated sodium hydroxide aqueous solution, and control the temperature of the reaction vessel at 35℃. Keep the mixture warm and stir for 80 min. After the reaction is complete, allow the reaction vessel to cool naturally to room temperature, filter the reaction solution, collect the filter cake, wash the filter cake 5 times with deionized water, and then transfer the filter cake to a drying oven at 60℃ and vacuum dry it to constant weight to obtain a layered solid of calcium, aluminum, and zinc phosphate.

[0039] Step 2: Preparation of calcium aluminum zinc fluorapatite solid solution Weigh out 10.0g of calcium aluminum zinc phosphate layered solid and 2.0g of sodium fluorosilicate, add them to the reaction vessel, mix and grind them evenly, then introduce nitrogen protection and heat the reaction vessel to 250℃, keep the temperature for 6h. After the reaction is completed, stop heating and nitrogen introduction, and let the reaction device cool naturally to room temperature. Take out the solid, wash it 5 times with anhydrous ethanol and deionized water, and then transfer the solid to a drying oven at 80℃ and vacuum dry it to constant weight to obtain calcium aluminum zinc fluoroapatite solid solution.

[0040] Example 9 This embodiment provides a method for preparing an aluminum zinc fluoroapatite solid solution, including the following steps: Step ①: Preparation of calcium, aluminum, and zinc phosphate layered solids Weigh out 50.0 mL of 0.3 mol / L calcium chloride aqueous solution, 25.0 mL of 0.2 mol / L aluminum chloride aqueous solution, 16.0 mL of 0.1 mol / L zinc chloride aqueous solution, and disodium hydrogen phosphate (0.6 times the molar amount of calcium ions in the reaction system) and add them to the reaction vessel. Stir the mixture, adjust the pH of the reaction system to 10.3 using saturated sodium hydroxide aqueous solution, and control the temperature of the reaction vessel at 30℃. Keep the mixture warm and stir for 70 min. After the reaction is complete, allow the reaction vessel to cool naturally to room temperature, filter the reaction solution, collect the filter cake, wash the filter cake four times with deionized water, and then transfer the filter cake to a drying oven at 60℃ and vacuum dry it to constant weight to obtain a layered solid of calcium, aluminum, and zinc phosphate.

[0041] Step 2: Preparation of calcium aluminum zinc fluorapatite solid solution Weigh out 10.0g of calcium aluminum zinc phosphate layered solid and 1.6g of sodium fluorosilicate, add them to the reaction vessel, mix and grind them evenly, then introduce nitrogen protection and heat the reaction vessel to 225℃, keep the temperature for 5h. After the reaction is completed, stop heating and nitrogen introduction, and let the reaction device cool naturally to room temperature. Take out the solid, wash it 4 times with anhydrous ethanol and deionized water, and then transfer the solid to a drying oven at 80℃ and vacuum dry it to constant weight to obtain calcium aluminum zinc fluoroapatite solid solution.

[0042] Example 10 This embodiment provides a highly efficient defluorination method for semiconductor fluoride-containing wastewater, comprising the following steps: Step 1: Preparation of primary fluoride-reducing effluent Weigh out 10.0L of semiconductor fluoride wastewater with a fluoride content of 1000mg / L and introduce it into the primary reaction tank for stirring. Add 3.0g of zinc-iron oxide composite microbeads prepared in Example 1 and adjust the pH of the reaction system to 5. Then control the temperature of the primary reaction tank to 20℃ and keep it warm and stirred for 20min. Subsequently, the reaction liquid is sent to the primary sedimentation tank for solid-liquid separation and the effluent is collected to obtain the primary fluoride-removing effluent.

[0043] Step 2: Preparation of complexed fluoride for deep effluent removal The primary fluoride-removed effluent was passed through a fixed-bed adsorption column containing zirconium zinc phosphonic acid hybrid material prepared in Example 4 at a flow rate of 4 BV / h. The empty bed contact time was 20 min. The influent pH was adjusted to 6.0, and the operating temperature was maintained at 25°C. The effluent was collected to obtain effluent with deep removal of complexed fluoride. The adsorption breakthrough was judged when the total fluoride concentration in the effluent first reached 8 mg / L. At that time, the operation was stopped and the zirconium zinc phosphonic acid hybrid material was replaced.

[0044] Step 3: Preparation of complexed fluoride for deep effluent removal 8.0 L of effluent from the deep removal of complexed fluoride was introduced into a three-stage crystallization reaction tank and stirred. 0.8 g of the calcium aluminum zinc fluoroapatite solid solution prepared in Example 7 was added to the three-stage crystallization reaction tank, and calcium chloride and disodium hydrogen phosphate were added until the calcium-phosphorus molar ratio was 1.67. The pH of the reaction system was adjusted to 7.5, the temperature of the three-stage crystallization reaction tank was controlled at 20°C, and the mixture was stirred for 40 min. Then, it was sent to the filtration unit for solid-liquid separation to obtain deeply defluorinated water.

[0045] Example 11 This embodiment provides a highly efficient defluorination method for semiconductor fluoride-containing wastewater, comprising the following steps: Step 1: Preparation of primary fluoride-reducing effluent Weigh out 10.0L of semiconductor fluoride-containing wastewater with a fluoride content of 1200mg / L and introduce it into the primary reaction tank for stirring. Add 5.0g of zinc-iron oxide composite microbeads prepared in Example 2 and adjust the pH of the reaction system to 6. Then control the temperature of the primary reaction tank to 30℃ and keep it warm and stirred for 30min. Subsequently, the reaction liquid is sent to the primary sedimentation tank for solid-liquid separation, and the effluent is collected to obtain the primary fluoride-removing effluent.

[0046] Step 2: Preparation of complexed fluoride for deep effluent removal The primary fluoride-removed effluent was passed through a fixed-bed adsorption column containing zirconium zinc phosphonic acid hybrid material prepared in Example 5 at a flow rate of 6 BV / h. The empty bed contact time was 30 min, the influent pH was adjusted to 7.0, and the operating temperature was maintained at 35°C. The effluent was collected to obtain effluent with deep removal of complexed fluoride. The adsorption breakthrough was judged when the total fluoride concentration in the effluent first reached 8 mg / L. At that time, the operation was stopped and the zirconium zinc phosphonic acid hybrid material was replaced.

[0047] Step 3: Preparation of complexed fluoride for deep effluent removal 8.0 L of effluent from the deep removal of complexed fluoride was introduced into a three-stage crystallization reaction tank and stirred. 1.2 g of calcium aluminum zinc fluoroapatite solid solution prepared in Example 8 was added to the three-stage crystallization reaction tank, and calcium chloride and disodium hydrogen phosphate were added until the calcium-phosphorus molar ratio was 1.67. The pH of the reaction system was adjusted to 8.5, the temperature of the three-stage crystallization reaction tank was controlled at 30°C, and the mixture was kept at this temperature and stirred for 60 min. Then, the mixture was sent to a filtration unit for solid-liquid separation to obtain deeply defluorinated water.

[0048] Example 12 This embodiment provides a highly efficient defluorination method for semiconductor fluoride-containing wastewater, comprising the following steps: Step 1: Preparation of primary fluoride-reducing effluent Weigh out 10.0L of semiconductor fluoride-containing wastewater with a fluoride content of 1100mg / L and introduce it into the primary reaction tank for stirring. Add 4.0g of zinc-iron oxide composite microbeads prepared in Example 3 and adjust the pH of the reaction system to 5. Then control the temperature of the primary reaction tank to 25℃ and keep it warm and stirred for 25min. Subsequently, the reaction liquid is sent to the primary sedimentation tank for solid-liquid separation, and the effluent is collected to obtain the primary fluoride-removing effluent.

[0049] Step 2: Preparation of complexed fluoride for deep effluent removal The primary fluoride-removed effluent was passed through a fixed-bed adsorption column containing zirconium zinc phosphonic acid hybrid material prepared in Example 6 at a flow rate of 5 BV / h. The empty bed contact time was 25 min, the influent pH was adjusted to 6.5, and the operating temperature was maintained at 30°C. The effluent was collected to obtain effluent with deep removal of complexed fluoride. The adsorption breakthrough was judged when the total fluoride concentration in the effluent first reached 8 mg / L. At that time, the operation was stopped and the zirconium zinc phosphonic acid hybrid material was replaced.

[0050] Step 3: Preparation of complexed fluoride for deep effluent removal 8.0 L of effluent from the deep defluorination process was introduced into a three-stage crystallization reactor and stirred. 1.0 g of the calcium aluminum zinc fluoroapatite solid solution prepared in Example 9 was added to the three-stage crystallization reactor, and calcium chloride and disodium hydrogen phosphate were added until the calcium-to-phosphorus molar ratio was 1.67. The pH of the reaction system was adjusted to 8.0, the temperature of the three-stage crystallization reactor was controlled at 25°C, and the mixture was stirred for 50 min. Then, the mixture was sent to a filtration unit for solid-liquid separation to obtain deeply defluorinated water.

[0051] Comparative Example 1 The difference between this comparative example and Example 12 is that step one is omitted, and in step two, an equal amount of semiconductor fluoride-containing wastewater is used to replace the primary fluoride removal effluent.

[0052] Comparative Example 2 The difference between this comparative example and Example 12 is that step two is omitted, and in step three, the primary defluorination effluent is used in an equal amount to replace the complexed fluoride deep removal effluent.

[0053] Comparative Example 3 The difference between this comparative example and Example 12 is that, in the preparation of the calcium aluminum zinc fluoroapatite solid solution used in step three, step ② is omitted, and in step three, an equal amount of calcium aluminum zinc phosphate layered solid is used to replace the calcium aluminum zinc fluoroapatite solid solution.

[0054] Performance testing: The fluoride content of semiconductor fluoride-containing wastewater and the prepared deep defluorinated water in Examples 10-12 and Comparative Examples 1-3 was determined according to the standard GB 7484-1987 "Determination of Fluoride in Water - Ion Selective Electrode Method", and the fluoride removal rate was calculated. The total phosphorus content of semiconductor fluoride-containing wastewater and the prepared deep defluorinated water in Examples 10-12 and Comparative Examples 1-3 was determined according to the standard HJ 671-2013 "Determination of Total Phosphorus in Water by Flow Injection-Ammonium Molybdate Spectrophotometric Method", and the total phosphorus removal rate was calculated. The contents of aluminum, copper, and iron ions in the semiconductor fluoride-containing wastewater and the prepared deep defluorinated water in Examples 10-12 and Comparative Examples 1-3 were determined according to the standard HJ 776-2015 "Determination of 32 Elements in Water by Inductively Coupled Plasma Atomic Emission Spectrometry". The removal rates of aluminum, copper, and iron ions were calculated, as shown in Table 1.

[0055] Table 1 - Performance Test Data for Each Sample Data Analysis: A comparative analysis of the data in Table 1 reveals that the deep defluorination water obtained after treating semiconductor fluoride-containing wastewater using this process achieves fluoride removal rates of 99.5%, total phosphorus removal rate of 98.4%, aluminum ion removal rate of 99.3%, copper ion removal rate of 98.0%, and iron ion removal rate of 98.7%. All these figures are superior to the comparative example, indicating that… In Comparative Example 1, step one was omitted, meaning that the wastewater did not undergo a pre-reduction process before entering step two. The original concentrations of free fluoride, complexed fluoride, metal ions, and phosphorus remained at high levels. Due to the lack of a pre-concentration reduction effect, the adsorption column in step two operated under a high pollution load, resulting in the rapid occupation of adsorption sites and premature adsorption breakthrough. The concentrations of fluoride and metal ions in the effluent increased rapidly. At the same time, the high concentration of complexed fluoride was not alleviated before entering step three, causing the subsequent crystallization and solidification stage to operate under a high solute background. Crystal growth was inhibited, and the crystallization process was prone to problems such as insufficient nucleation and loose structure. Ultimately, this led to a significant decrease in the efficiency of deep defluorination and metal fixation. Overall, due to the loss of the pre-concentration reduction process, the load on the entire system increased significantly, resulting in the inability to smoothly connect the synergistic chain and a significant reduction in the comprehensive treatment performance. In Comparative Example 2, step two was omitted, causing the wastewater to directly enter the crystallization and solidification stage after only completing the first-stage fluoride removal. Since the complex-breaking stage was not performed, a large amount of highly stable aluminum-fluorine, silicon-fluorine, and metal complexes remained. When entering step three, they were difficult to react fully with the added calcium and phosphorus sources, resulting in a large number of undissociated complex structures in the crystallization tank. This competitively inhibited the calcium-phosphorus nucleation process, making it difficult for crystals to form a uniform and dense structure, and significantly reducing the solidification efficiency. At the same time, under these conditions, complexed metal ions were not easily encapsulated or dissolved into the crystal structure. After solid-liquid separation, they remained in the aqueous phase, resulting in a significant increase in metal and fluorine levels in the effluent. Overall, the omission of the complex-breaking step allowed multiple pollutants in the wastewater to enter the crystallization stage in a stable complex form, disrupting the downstream lattice growth and solidification pathways, and thus leading to a significant decrease in the overall removal efficiency of composite pollutants. In Comparative Example 3, the solid material used in step three lost the solid solution structure constructed in step ② during the preparation process. This resulted in the wastewater entering step three lacking a suitable lattice growth interface during the crystallization stage. Furthermore, due to insufficient lattice defect structure and substitution sites, the residual fluorine, phosphorus, and metal ions in the wastewater could not easily embed into the crystal to form a stable solid phase in a short time. This led to phenomena such as reduced nucleation rate, irregular crystal growth, and insufficient precipitation density. Such incomplete crystallization would produce loose particles, which would be difficult to achieve deep fixation and would also be prone to partial redissolution in subsequent solid-liquid separation, thereby increasing the content of fluorine, phosphorus, and metal ions in the effluent. Overall, because the crystallizing material did not form a suitable solid solution structure, the crystal growth momentum was insufficient and the solidification path was blocked, resulting in the stability of the final effluent and the pollutant removal depth being significantly lower than those in the example. In conclusion, this process for treating semiconductor wastewater containing fluoride achieves continuous, deep, and stable removal of free fluoride, complexed fluoride, phosphorus, and various metal ions through pretreatment with zinc-iron oxide composite microspheres, complex-breaking adsorption with zirconium-zinc phosphonic acid hybrid materials, and crystallization and solidification with calcium-aluminum-zinc fluorophosphate solid solution. The sequential order, reaction conditions, and material structure characteristics of each treatment unit are fully utilized in the process flow, allowing pollutants to be gradually transformed, reduced, and fixed at different stages. This avoids the problem of single treatment methods being unable to cover multiple forms of pollutants, resulting in high fluoride removal rates, total phosphorus removal rates, and removal rates of various metal ions. The effluent quality is stable and reliable. The overall process design allows multiple components in complex wastewater to be gradually weakened and ultimately solidified, taking into account mechanisms such as fluoride reduction, complex breaking, and solidification, thus improving the controllability and effectiveness of deep treatment and achieving the goal of highly efficient purification of high-load semiconductor wastewater.

[0056] 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 specific implementations. 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 highly efficient defluorination method suitable for semiconductor fluoride-containing wastewater, characterized in that, Includes the following steps: S1. The semiconductor fluorine-containing wastewater is introduced into the primary reaction tank and stirred. After adding zinc-iron oxide composite microspheres, the pH of the reaction system is adjusted to 5-6. Then, the temperature of the primary reaction tank is controlled at 20-30℃ and stirred for 20-30 minutes. Subsequently, the reaction liquid is sent to the primary sedimentation tank for solid-liquid separation, and the effluent is collected to obtain the primary fluoride-removing effluent. S2. Use zirconium zinc phosphonic acid hybrid material to perform secondary defluorination on the primary defluorination effluent to obtain effluent with deep removal of complexed fluoride. S3. The effluent from the deep removal of complexed fluoride is introduced into a three-stage crystallization reaction tank and stirred. Calcium aluminum zinc fluoroapatite solid solution is added to the three-stage crystallization reaction tank, along with calcium chloride and disodium hydrogen phosphate. The pH of the reaction system is adjusted to 7.5-8.

5. The temperature of the three-stage crystallization reaction tank is controlled at 20-30℃ and stirred for 40-60 minutes. Then, it is sent to a filtration unit for solid-liquid separation to obtain deeply defluorinated water.

2. The efficient defluorination method for semiconductor fluoride-containing wastewater according to claim 1, characterized in that, In step S1, the ratio of the amount of semiconductor fluoride-containing wastewater to zinc-iron oxide composite microspheres is 1L:300-500mg, wherein the fluoride content of the semiconductor fluoride-containing wastewater is 1000-1200mg / L.

3. The efficient defluorination method for semiconductor fluoride-containing wastewater according to claim 1, characterized in that, In step S2, the secondary defluorination includes: passing the primary defluorinated effluent through a fixed-bed adsorption column packed with zirconium zinc phosphonic acid hybrid material at a flow rate of 4-6 BV / h, with an empty bed contact time of 20-30 min, adjusting the influent pH to 6.0-7.0, maintaining the operating temperature at 25-35℃, collecting the effluent to obtain effluent with deep removal of complexed fluoride, and using the first occurrence of a total fluoride concentration of 8 mg / L in the adsorption column effluent as the adsorption breakthrough criterion, stopping the operation and replacing the zirconium zinc phosphonic acid hybrid material.

4. The efficient defluorination method for semiconductor fluoride-containing wastewater according to claim 1, characterized in that, In step S3, the ratio of the amount of complexed fluoride deep-removed effluent to the calcium aluminum zinc fluoroapatite solid solution is 1L:100-150mg, wherein calcium chloride and disodium hydrogen phosphate are added as needed to make the calcium-phosphorus molar ratio 1.

67.

5. The efficient defluorination method for semiconductor fluoride-containing wastewater according to claim 1, characterized in that, The zinc-iron oxide composite microspheres were prepared by the following method: A1. Add magnesium hydroxide and deionized water to the reaction vessel and stir. After mixing evenly, introduce carbon dioxide gas to control the pH of the reaction system to 8.5-9.

5. Then heat the reaction vessel to 30-40℃ and continuously introduce carbon dioxide. Keep the reaction at this temperature for 60-90 minutes. Post-processing yields porous alkaline magnesium carbonate microspheres. A2. Porous alkaline magnesium carbonate microspheres, 0.2 mol / L ferrous sulfate aqueous solution, 0.2 mol / L zinc sulfate aqueous solution, and deionized water are added to a reaction vessel and stirred. Under stirring conditions, saturated sodium hydroxide aqueous solution is added to adjust the pH of the reaction system to 8.0-9.0, and air is introduced. The reaction vessel is then heated to 30-35℃ and kept at this temperature for 40-60 min. The reaction solution is then transferred to a closed hydrothermal reaction vessel, and the hydrothermal reaction vessel is heated to 120-160℃ and kept at this temperature with stirring for 4-6 h. The zinc-iron oxide composite microspheres are obtained after post-treatment.

6. The efficient defluorination method for semiconductor fluoride-containing wastewater according to claim 5, characterized in that, In step A1, the ratio of magnesium hydroxide to deionized water is 1-2 g: 10 mL; in step A2, the ratio of porous alkaline magnesium carbonate microspheres, 0.2 mol / L ferrous sulfate aqueous solution, 0.2 mol / L zinc sulfate aqueous solution, and deionized water is 3-5 g: 60-80 mL: 60-80 mL: 100-120 mL, wherein the air flow rate is 0.8-1.0 L / min.

7. The efficient defluorination method for semiconductor fluoride-containing wastewater according to claim 1, characterized in that, The zirconium zinc phosphonate hybrid material is prepared by the following method: B1. Add aminotrimethylenephosphonic acid, 37wt% formaldehyde aqueous solution, ethylenediamine, deionized water and anhydrous ethanol to a reaction vessel and stir. After purging with nitrogen, adjust the pH of the reaction system to 3-4 with acetic acid. Then heat the reaction vessel to 60-70℃ and stir for 120-150 min. Post-treatment yields polyphosphonic acid polyamine gel. B2. Add polyphosphonic acid polyamine gel, 0.2 mol / L zirconium oxychloride aqueous solution, 0.2 mol / L zinc nitrate aqueous solution, deionized water and anhydrous ethanol to a reaction vessel and stir. Purge with nitrogen and adjust the pH of the reaction system to 2-3 with acetic acid. Then raise the temperature of the reaction vessel to 40-60℃ and keep it at this temperature for 2-4 hours. Post-processing yields zirconium zinc phosphonic acid hybrid material.

8. The efficient defluorination method for semiconductor fluoride-containing wastewater according to claim 7, characterized in that, In step B1, the ratio of aminotrimethylenephosphonic acid, 37wt% formaldehyde aqueous solution, ethylenediamine, deionized water, and anhydrous ethanol is 2-3g:4-6g:1-2g:20mL:80mL; in step B2, the ratio of polyphosphonic acid polyamine gel, 0.2mol / L zirconium oxychloride aqueous solution, 0.2mol / L zinc nitrate aqueous solution, deionized water, and anhydrous ethanol is 1g:20-30mL:20-30mL:20mL:80mL.

9. The efficient defluorination method for semiconductor fluoride-containing wastewater according to claim 1, characterized in that, The calcium aluminum zinc fluorapatite solid solution was prepared by the following method: C1. Add 0.3 mol / L calcium chloride aqueous solution, 0.2 mol / L aluminum chloride aqueous solution, 0.1 mol / L zinc chloride aqueous solution and the calculated amount of disodium hydrogen phosphate to the reaction vessel and stir. Adjust the pH of the reaction system to 10.0-10.5 with saturated sodium hydroxide aqueous solution, control the temperature of the reaction vessel at 25-35℃, keep it at the temperature and stir for 60-80 min, and then process to obtain calcium aluminum zinc phosphate layered solid. C2. After mixing and grinding the layered solid calcium aluminum zinc phosphate and sodium fluorosilicate into a reaction vessel, nitrogen gas is introduced for protection, and the reaction vessel is heated to 200-250℃ and kept at this temperature for 4-6 hours. The calcium aluminum zinc fluoroapatite solid solution is then obtained through post-treatment.

10. The efficient defluorination method for semiconductor fluoride-containing wastewater according to claim 9, characterized in that, In step C1, the ratio of the 0.3 mol / L calcium chloride aqueous solution, the 0.2 mol / L aluminum chloride aqueous solution, and the 0.1 mol / L zinc chloride aqueous solution is 4-6 mL: 2-3 mL: 1-2 mL, wherein the amount of disodium hydrogen phosphate added is 0.6 times the molar amount of calcium ions in the reaction system; in step C2, the ratio of the calcium aluminum zinc phosphate layered solid and sodium fluorosilicate is 10 g: 1-2 g.

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