A deep defluorination synergistic Fenton catalytic material and its preparation method

Abstract

The present invention relates to the field of sewage treatment technology, and in particular to a deep fluorine removal synergistic Fenton catalytic material and a preparation method thereof, the method comprising: preparing a calcium-doped aluminum hydroxide precursor by a precipitation method based on an aluminum-containing metal salt, a pH regulator, a dispersant and calcium chloride; preparing a magnesium-modified calcium-doped aluminum oxide nanomaterial by a mechanical ball milling method based on a magnesium metal salt, a modifier and a calcium-doped aluminum hydroxide precursor; and preparing a deep fluorine removal synergistic Fenton catalytic material by a hydrothermal method based on a magnesium-modified calcium-doped aluminum oxide nanomaterial, ammonium ferrous sulfate, thiourea and a cross-linking agent. The aluminum, iron and magnesium metal elements in the deep fluorine removal synergistic Fenton catalytic material synthesized by the present invention can efficiently adsorb fluoride ions in wastewater, and at the same time, the metal elements can serve as Fenton reaction catalysts to catalyze the degradation of organic matter in the wastewater, thereby avoiding the generation of a large amount of sludge in the traditional Fenton reaction process, and realizing green and efficient deep fluorine removal from wastewater while catalyzing the degradation of organic pollutants.

Description

Technical field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a deep fluorine removal synergistic Fenton catalytic material and a preparation method thereof. [Background Technology]

[0002] Fluoride pollution primarily originates from industries such as semiconductors, panels, new energy, and chemicals. These industries generate large volumes of fluoride-containing wastewater, with fluoride concentrations as high as 400-2000 mg / L, posing a significant threat to the ecological environment. Against the backdrop of the "dual carbon" goals, my country's newly connected photovoltaic power generation capacity reached 306 million kilowatts by the end of 2021, ranking first globally for seven consecutive years. The production of crystalline silicon materials for solar cells inevitably generates large amounts of fluoride-containing wastewater. Lithium hexafluorophosphate (LiFPO) is widely used as an electrolyte salt in lithium-ion batteries. Polyvinylidene fluoride (PVDF), a special fluorinated polymer, is primarily used as a positive electrode binder in lithium batteries. The rapid development of the new energy industry has led to a surge in the discharge of fluoride-containing wastewater. While traditional calcium salt precipitation defluoridation methods are effective, primarily by adding lime and calcium chloride to fluoride-containing wastewater to form a fluoride precipitate, achieving solid-liquid separation and removing fluoride ions, they are limited by the reaction solubility product of calcium fluoride and the effectiveness of solid-liquid separation, effectively reducing the fluoride concentration in the effluent to 10-20 mg / L. The environment's carrying capacity for fluoride, a Class 3 carcinogen, is decreasing. Existing emission standards no longer meet environmental protection requirements. Currently, as environmental protection policies tighten across the country, fluoride emission requirements have been gradually raised to below 1-1.5 mg / L. However, traditional deep defluoridation materials are significantly affected by organic pollutants during practical application, making it difficult to achieve stable deep defluoridation in the presence of organic matter. Therefore, the development of new defluoridation materials is urgently needed to achieve stable deep defluoridation despite organic interference. [Summary of the invention]

[0003] The embodiments of the present application provide a deep defluorination synergistic Fenton catalytic material and its preparation method and application, aiming to solve the technical problem that traditional deep defluorination materials are greatly interfered with by organic pollutants during actual application and are difficult to stably perform deep defluorination under the coexistence of organic matter.

[0004] In the first aspect, the embodiment of the present application provides a method for preparing a deep defluorination synergistic Fenton catalytic material. The method comprises the following steps: based on the first component, a calcium-doped aluminum hydroxide precursor is prepared by a precipitation method; wherein, the first component for preparing the calcium-doped aluminum hydroxide precursor includes: an aluminum-containing metal salt, a pH regulator, a dispersant, and calcium chloride; based on the second component, a magnesium-modified calcium-doped aluminum oxide nanomaterial is prepared by a mechanical ball milling method; wherein, the second component for preparing the magnesium-modified calcium-doped aluminum oxide nanomaterial includes: a magnesium metal salt, a modifier, and the calcium-doped aluminum hydroxide precursor; based on the third component, the deep defluorination synergistic Fenton catalytic material is prepared by a hydrothermal method; wherein, the third component for preparing the deep defluorination synergistic Fenton catalytic material includes: the magnesium-modified calcium-doped aluminum oxide nanomaterial, ammonium ferrous sulfate, thiourea, and a cross-linking agent.

[0005] Optionally, the dispersant is selected from one or more of sodium tripolyphosphate, sodium hexametaphosphate and sodium pyrophosphate.

[0006] Optionally, the modifier is one or more of potassium ferrate, potassium permanganate and potassium superoxide.

[0007] Optionally, the cross-linking agent is one or more of cysteamine, tetravinylpentylamine, and polyoxypropylenediamine.

[0008] Optionally, the cross-linking agent is cysteamine.

[0009] Optionally, the calcium-doped aluminum hydroxide precursor is prepared by a precipitation method based on the first component, specifically including: dissolving a preset weight of aluminum metal salt in deionized water to obtain an aluminum metal salt solution; under stirring conditions, adding a pH regulator dropwise to the aluminum metal salt solution to adjust the pH value to 10-11; after the pH value is adjusted, adding a preset weight of a dispersant and adding a preset volume of calcium chloride solution dropwise to obtain a first mixture; stirring the first mixture at room temperature for a preset first time and letting it stand for a second time to obtain a first reactant; purifying the first reactant to obtain the calcium-doped aluminum hydroxide precursor.

[0010] Optionally, the preset weight of aluminum metal salt is: 5-10g of aluminum chloride; the deionized water is 50-100ml; the pH regulator is ammonia water; the preset weight of dispersant is: 2-5g of sodium tripolyphosphate, sodium hexametaphosphate or sodium pyrophosphate; the preset volume of calcium chloride solution is: 20-50ml of 5-10% concentration calcium chloride solution.

[0011] Optionally, the magnesium-modified calcium-doped alumina nanomaterial is prepared based on the second component by mechanical ball milling, specifically comprising: uniformly mixing the calcium-doped aluminum hydroxide precursor, magnesium metal salt and modifier of preset weight to obtain a second mixture; placing the second mixture in a high-energy ball mill, and ball milling for 1 to 4 hours at 2000 r / min to 3000 r / min to obtain the magnesium-modified calcium-doped alumina nanomaterial.

[0012] Optionally, the second mixture includes the following components: 5-10 g of calcium-doped aluminum hydroxide precursor; 2-5 g of magnesium chloride, magnesium sulfate or magnesium nitrate; and 1-5 g of potassium ferrate, potassium permanganate or potassium superoxide.

[0013] Optionally, the deep fluorine removal synergistic Fenton catalytic material is prepared by a hydrothermal method based on the third component, specifically including: adding a preset weight of magnesium-modified calcium-doped alumina nanomaterial to an ammonium ferrous sulfate solution, and adding a preset weight of thiourea and stirring to form a third mixture; adding anhydrous ethanol dissolved with the cross-linking agent dropwise to the third mixture, and heating the reaction in a water bath to obtain a second reactant; using a two-step calcination method on the second reactant to obtain the deep fluorine removal synergistic Fenton catalytic material; wherein the two-step calcination method includes: calcining at a preset first temperature for 2 hours under a hydrogen reducing atmosphere; and carbonizing at a preset second temperature for 2 hours. Optionally, the preset weight of magnesium-modified calcium-doped alumina nanomaterial is: 5 to 10 g of magnesium-modified calcium-doped alumina nanomaterial; the ammonium ferrous sulfate solution is: 50 to 100 ml, 5% to 10% concentration of ammonium ferrous sulfate solution; the preset weight of thiourea is: 2 to 5 g of thiourea; the cross-linking agent is: 1 to 5 g of cross-linking agent cysteamine, tetravinylpentylamine or polyoxypropylenediamine; the anhydrous ethanol is: 20 to 50 ml; the heating reaction is: at 95 to 98° C., react for 8 to 12 hours.

[0014] In a second aspect, an embodiment of the present application provides a deep fluorine removal synergistic Fenton catalytic material, and the deep fluorine removal synergistic Fenton catalytic material is prepared by the preparation method described above.

[0015] The aluminum, iron and magnesium metal elements in the deep fluoride removal synergistic Fenton catalytic material synthesized by the present invention can efficiently adsorb and capture fluoride ions in wastewater. At the same time, the metal elements can serve as Fenton reaction catalysts to catalyze the degradation of organic matter in the wastewater.

[0016] When this deep defluorination synergistic Fenton catalytic material is used as a fluidized bed support in the fluidized bed process for deep wastewater treatment, defluorination and Fenton catalyst crystal nuclei can be formed on the material surface during the fluidization of the fluidized bed. The material does not require frequent regeneration for defluorination, and at the same time avoids the generation of a large amount of sludge in the traditional Fenton reaction process, thereby achieving green and efficient deep defluorination of wastewater and catalytic degradation of organic pollutants.

[0017] More embodiments of the advantageous aspects of the above methods, devices and components are described in detail below. All disclosures in this specification are merely exemplary, and those skilled in the art can easily make appropriate adjustments without departing from the spirit and scope of the invention disclosed and claimed in this application.

Brief Description of the Drawings

[0018] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0019] Figure 1 Schematic diagram of the preparation method provided in the examples of the present application. [Specific implementation method]

[0020] For ease of understanding of the present invention, the present invention will be described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or there can be one or more centered elements therebetween. When an element is described as being "connected to" another element, it can be directly connected to the other element, or there can be one or more centered elements therebetween. The orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "bottom" etc. used in this specification is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0021] Unless otherwise defined, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which this invention belongs. The terms used in this specification and in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the relevant listed items.

[0022] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] Fluoride removal agents utilize strong adsorption and ion exchange to remove fluorine, making them widely used in wastewater treatment. However, traditional fluoride removal materials suffer from significant interference from organic pollutants and difficulty in achieving stable fluoride removal.

[0024] Therefore, the embodiment of the present invention provides a deep defluorination synergistic Fenton catalytic material that is convenient and can be prepared on a large scale. It can be used in a fluidized bed process for deep wastewater treatment as a fluidized bed support. During the fluidization process of the fluidized bed, the deep defluorination synergistic Fenton catalytic material provided by the present invention can form defluorination and Fenton catalyst crystal nuclei on the surface of the material, and can catalyze the degradation of organic matter in the wastewater while removing fluorine. Thus, it is possible to achieve the goal of not requiring frequent regeneration, avoiding the problem of generating a large amount of sludge in the traditional Fenton reaction process, and has good application prospects and usage advantages in wastewater treatment.

[0025] Figure 1 This is a flow chart of the preparation method of the deep defluorination synergistic Fenton catalytic material provided by the embodiment of the present invention. Figure 1 As shown, the method includes:

[0026] Step 10: Based on the first component, a calcium-doped aluminum hydroxide precursor is prepared by a precipitation method.

[0027] The first component for preparing the calcium-doped aluminum hydroxide precursor includes: an aluminum-containing metal salt, a pH regulator, a dispersant, and calcium chloride. The dispersant can be one or more of sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate.

[0028] Specifically, step 10 includes: weighing 5-10g of aluminum chloride and dissolving it in 50-100ml of deionized water, adding ammonia water dropwise under stirring until the pH value is 10-11, then adding 2-5g of dispersant sodium tripolyphosphate, sodium hexametaphosphate or sodium pyrophosphate, and then adding 20-50ml of 5-10% calcium chloride solution dropwise to obtain a preliminarily mixed reactant.

[0029] The preliminarily mixed reactants are stirred at room temperature for 2 to 6 hours and then aged for 18 to 24 hours to obtain a fully reacted intermediate product. The intermediate product is finally filtered, washed thoroughly with deionized water until neutral, dried, and ground to obtain a calcium-doped aluminum hydroxide precursor.

[0030] This process uses alumina nanoflowers as the core and dispersants such as sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate to prevent aluminum atoms from agglomerating during aging. Furthermore, calcium ions combine with phosphate ions in the dispersant under alkaline conditions to form calcium hydroxyphosphate, which is then doped into the interlayers of the alumina nanoflowers, enhancing the material's ability to adsorb fluoride ions.

[0031] Step 20: Based on the second component, magnesium-modified calcium-doped alumina nanomaterials are prepared by mechanical ball milling.

[0032] The second component for preparing the magnesium-modified calcium-doped aluminum oxide nanomaterial includes: a magnesium metal salt, a modifier, and the calcium-doped aluminum hydroxide precursor. The modifier can be one or more of potassium ferrate, potassium permanganate, or potassium superoxide.

[0033] Specifically, step 20 includes mixing 5-10 g of a calcium-doped aluminum hydroxide precursor, 2-5 g of magnesium chloride, magnesium sulfate, or magnesium nitrate, and 1-5 g of a modifier (potassium ferrate, potassium permanganate, or potassium superoxide), and then placing the mixture in a high-energy ball mill. The mixture is milled at 2000-3000 rpm for 1-4 hours to produce a magnesium-modified calcium-doped aluminum oxide nanomaterial.

[0034] During this step, potassium ferrate, potassium permanganate, or potassium superoxide reacts with metallic magnesium salts during high-speed ball milling, promoting the formation of magnesium peroxide within the lattice of the calcium-doped aluminum hydroxide precursor, thereby forming a magnesium-modified calcium-doped aluminum oxide nanomaterial. The addition of magnesium peroxide improves the material's stability and adsorption properties. Furthermore, magnesium peroxide promotes the Fenton reaction to generate ·OH, enhancing the material's ability to degrade organic pollutants.

[0035] Step 30: Based on the third component, the deep defluorination synergistic Fenton catalytic material is prepared by a hydrothermal method.

[0036] Among them, the third component for preparing the deep defluorination synergistic Fenton catalytic material includes: the magnesium-modified calcium-doped alumina nanomaterial, ammonium ferrous sulfate, thiourea and a cross-linking agent.

[0037] Specifically, step 30 includes: weighing 5 to 10 g of magnesium-modified calcium-doped alumina nanomaterial, adding it to a three-necked flask containing 50 to 100 ml of 5% to 10% ammonium ferrous sulfate solution, and then adding 2 to 5 g of thiourea and stirring to form a preliminary mixed solution. Then, 1 to 5 g of cross-linking agent cysteamine, tetravinylpentylamine or polyoxypropylenediamine is dissolved in 20 to 50 ml of anhydrous ethanol and added dropwise to the mixed solution. Under water bath heating conditions, the reaction is carried out at 95 to 98 ° C for 8 to 12 hours to obtain the target product, and the target product is filtered, washed and dried. Finally, the dried target product is subjected to a two-step calcination method, first calcined at 300 ° C for 2 hours under a hydrogen reducing atmosphere, and then carbonized at 600 ° C for 2 hours. After cooling to room temperature, the obtained product is ground, which is the deep defluorination synergistic Fenton catalytic material of the present application.

[0038] Here, thiourea can complex with ferrous ions and form Fe-S bonds on the surface of magnesium-modified calcium-doped alumina nanomaterials, which can accelerate the process of the material's Fenton-like reaction of organic pollutants. In addition, it can also play a reducing role, accelerate electron transfer and promote Fe 3+ Fe 2+ transformation.

[0039] This step involves adding a crosslinking agent, which is one or more of cysteamine, tetravinylpentylamine, and polyoxypropylenediamine. Due to its small size, the molecular crosslinking agent has high crosslinking uniformity and can be flexibly adjusted within a small range to form a uniform network structure, thereby improving the strength and stability of the material. The deep defluorination synergistic Fenton catalytic material prepared using the crosslinking agent has a larger specific surface area and porous structure, which improves the material's adsorption capacity for fluoride ions and the efficiency of free radical generation when degrading organic pollutants, thereby improving the material's removal effect on pollutants.

[0040] The fluorine removal synergistic Fenton catalytic material of the present invention is used in a fluidized bed process for advanced wastewater treatment. As a support for the fluidized bed, the aluminum, calcium, magnesium, and iron metal elements in the material can efficiently adsorb and capture fluoride ions in the wastewater. The synergistic adsorption of multiple metal ions results in a high fluoride ion adsorption capacity, with a maximum adsorption value of up to 50 mg / g. Furthermore, during the fluidization process of the fluidized bed, the material can form fluorine removal crystal nuclei on its surface. This material eliminates the need for frequent regeneration for fluorine removal, while also avoiding the large amounts of sludge generated during the conventional process reaction.

[0041] The fluorine removal synergistic Fenton catalytic material of the present invention is used in a fluidized bed process for advanced wastewater treatment. As a support for the fluidized bed, the metal elements in the material act as Fenton reaction catalysts. Adding a small amount of Fenton reagent can efficiently catalyze the degradation of organic matter in the wastewater. Furthermore, during the fluidization process of the fluidized bed, FeOOH crystals form on the material surface. These FeOOH crystals have a certain net-capturing and adsorbing effect on fluoride ions and can further act as a Fenton-like reaction catalyst to degrade organic pollutants. This allows for deep fluorine removal even in the presence of high organic pollutant concentrations.

[0042] The fluorine removal synergistic Fenton catalytic material of the present invention is applied to the fluidized bed process for deep treatment of wastewater. As a carrier of the fluidized bed, after the crystal nuclei adsorbed with fluorine on the surface of the material grow to maturity, the mature crystal nuclei can be discharged from the fluidized bed, and the high-fluorine-containing crystals on the surface of the material can be recovered for resource utilization.

[0043] The following describes in detail the preparation method of the deep defluorination synergistic Fenton catalytic material provided by the embodiments of the present invention and the wastewater treatment performance of the deep defluorination synergistic Fenton catalytic material in combination with specific embodiments.

[0044] Example 1

[0045] The preparation process of the deep defluorination synergistic Fenton catalytic material of this embodiment is as follows:

[0046] (1) 10 g of aluminum chloride was weighed and dissolved in 100 ml of deionized water. Ammonia water was added dropwise under stirring until the pH value was 10. Then, 5 g of sodium tripolyphosphate (a dispersant) was added. Then, 50 ml of 10% calcium chloride solution was added dropwise to obtain a preliminarily mixed reactant.

[0047] (2) The reactants preliminarily mixed in (1) were stirred at room temperature for 6 hours and then allowed to stand for 18 hours to obtain a complete intermediate product;

[0048] (3) filtering the intermediate product precipitate, washing it thoroughly with deionized water until it is neutral, drying it, and grinding it to obtain a calcium-doped aluminum hydroxide precursor;

[0049] (4) 10 g of calcium-doped aluminum hydroxide precursor, 5 g of magnesium chloride, and 2 g of potassium ferrate (a modifier) ​​were mixed evenly and placed in a high-energy ball mill for milling at 2000 r / min for 2 h to obtain magnesium-modified calcium-doped aluminum oxide nanomaterials;

[0050] (5) Weigh 10 g of magnesium-modified calcium-doped alumina nanomaterial and add it to a three-necked flask containing 100 ml of 10% ammonium ferrous sulfate solution, then add 5 g of thiourea and stir to form a preliminary mixed solution;

[0051] (6) 50 ml of anhydrous ethanol containing 2 g of the crosslinker cysteamine was added dropwise to the mixture in (5). The mixture was then heated in a water bath at 95°C for 8 h, filtered, washed, and dried to obtain the desired product.

[0052] (7) The target product in (6) was calcined in a two-step manner, first at 300 °C for 2 h in a hydrogen reducing atmosphere, then carbonized at 600 °C for 2 h, and then ground to obtain a deep defluorination synergistic Fenton catalytic material.

[0053] Example 2

[0054] The preparation process of the deep defluorination synergistic Fenton catalytic material of this embodiment is as follows:

[0055] (1) 10 g of aluminum chloride was weighed and dissolved in 100 ml of deionized water. Ammonia water was added dropwise under stirring until the pH value was 10. Then, 5 g of sodium hexametaphosphate as a dispersant was added. Then, 50 ml of 10% calcium chloride solution was added dropwise to obtain a preliminary mixed reactant.

[0056] (2) The reactants preliminarily mixed in (1) were stirred at room temperature for 6 hours and then allowed to stand for 18 hours to obtain a complete intermediate product;

[0057] (3) filtering the intermediate product precipitate, washing it thoroughly with deionized water until it is neutral, drying it, and grinding it to obtain a calcium-doped aluminum hydroxide precursor;

[0058] (4) 10 g of calcium-doped aluminum hydroxide precursor, 5 g of magnesium chloride, and 2 g of modifier potassium permanganate were mixed evenly and placed in a high-energy ball mill for milling at 2000 r / min for 1 h to obtain magnesium-modified calcium-doped aluminum oxide nanomaterials;

[0059] (5) Weigh 10 g of magnesium-modified calcium-doped alumina nanomaterial and add it to a three-necked flask containing 100 ml of 10% ammonium ferrous sulfate solution, then add 5 g of thiourea and stir to form a preliminary mixed solution;

[0060] (6) 50 ml of anhydrous ethanol containing 2 g of the crosslinker tetravinylpentylamine was added dropwise to the mixture in (5). The mixture was then heated in a water bath at 95°C for 8 h, filtered, washed, and dried to obtain the desired product.

[0061] (7) The target product in (6) was calcined in a two-step manner, first at 300 °C for 2 h in a hydrogen reducing atmosphere, then carbonized at 600 °C for 2 h, and then ground to obtain a deep defluorination synergistic Fenton catalytic material.

[0062] Example 3

[0063] The preparation process of the deep defluorination synergistic Fenton catalytic material of this embodiment is as follows:

[0064] (1) 10 g of aluminum chloride was weighed and dissolved in 100 ml of deionized water. Ammonia water was added dropwise under stirring until the pH value was 10. Then, 5 g of sodium pyrophosphate as a dispersant was added. Then, 50 ml of 10% calcium chloride solution was added dropwise to obtain a preliminary mixed reactant.

[0065] (2) The reactants preliminarily mixed in (1) were stirred at room temperature for 6 hours and then allowed to stand for 18 hours to obtain a complete intermediate product;

[0066] (3) filtering the intermediate product precipitate, washing it thoroughly with deionized water until it is neutral, drying it, and grinding it to obtain a calcium-doped aluminum hydroxide precursor;

[0067] (4) 10 g of calcium-doped aluminum hydroxide precursor, 5 g of magnesium chloride, and 2 g of modifier potassium superoxide were mixed evenly and placed in a high-energy ball mill for milling at 2000 r / min for 1 h to obtain magnesium-modified calcium-doped aluminum oxide nanomaterials;

[0068] (5) Weigh 10 g of magnesium-modified calcium-doped alumina nanomaterial and add it to a three-necked flask containing 100 ml of 10% ammonium ferrous sulfate solution, then add 5 g of thiourea and stir to form a preliminary mixed solution;

[0069] (6) 50 ml of anhydrous ethanol containing 2 g of the crosslinker polyoxypropylene diamine was added dropwise to the mixture in (5). The mixture was then heated in a water bath at 95°C for 8 h, filtered, washed, and dried to obtain the target product.

[0070] (7) The target product in (6) was calcined in a two-step manner, first at 300 °C for 2 h in a hydrogen reducing atmosphere, then carbonized at 600 °C for 2 h, and then ground to obtain a deep defluorination synergistic Fenton catalytic material.

[0071] Example 4

[0072] The preparation process of the deep defluorination synergistic Fenton catalytic material of this embodiment is as follows:

[0073] (1) 10 g of aluminum chloride was weighed and dissolved in 100 ml of deionized water. Ammonia water was added dropwise under stirring until the pH value was 9. Then, 1 g of sodium tripolyphosphate (a dispersant) was added. Then, 50 ml of 10% calcium chloride solution was added dropwise to obtain a preliminarily mixed reactant.

[0074] (2) The reactants preliminarily mixed in (1) were stirred at room temperature for 6 hours and then allowed to stand for 18 hours to obtain a complete intermediate product;

[0075] (3) filtering the intermediate product precipitate, washing it thoroughly with deionized water until it is neutral, drying it, and grinding it to obtain a calcium-doped aluminum hydroxide precursor;

[0076] (4) 10 g of calcium-doped aluminum hydroxide precursor, 1 g of magnesium chloride, and 1 g of modifier potassium ferrate were mixed evenly and placed in a high-energy ball mill for ball milling reaction at 1000 r / min for 0.5 h to obtain magnesium-modified calcium-doped aluminum oxide nanomaterials;

[0077] (5) Weigh 10 g of magnesium-modified calcium-doped alumina nanomaterial and add it to a three-necked flask containing 100 ml of 10% ammonium ferrous sulfate solution, and then add 1 g of thiourea and stir to form a preliminary mixed solution;

[0078] (6) 1 g of the cross-linking agent cysteamine dissolved in 50 ml of anhydrous ethanol was added dropwise to the mixture in (5). The mixture was then heated in a water bath at 80°C for 8 h, filtered, washed, and dried to obtain the desired product.

[0079] (7) The target product in (6) was carbonized at 600 °C for 2 h in a hydrogen reducing atmosphere, cooled to room temperature, and ground to obtain a deep defluorination synergistic Fenton catalytic material.

[0080] Control experimental group

[0081] The preparation process of the control experimental group is basically the same as that of Example 1, with the only difference between the two being that no dispersant is added in step (1), no modifier is added in step (3), and no cross-linking agent is added in step (4).

[0082] Application effect comparison:

[0083] Actual fluorine-containing organic wastewater was taken from an industrial wastewater treatment plant and passed into a fluidized bed wastewater treatment reactor, and was added to the deep fluorine removal synergistic Fenton catalytic materials synthesized by the preparation methods in Examples 1-4 and the control experimental group at a dosage of 5 g / L.

[0084] Then, aeration and stirring were used to fluidize the deep fluoride removal synergistic Fenton catalytic material in the wastewater to be treated, and 50 mg / L hydrogen peroxide was added and reacted for 1 hour. The removal effects of the materials synthesized in Examples 1 to 4 on fluoride and COD (chemical oxygen demand) are shown in Table 1:

[0085] Table 1: Actual application effects of materials in different embodiments

[0086]

[0087] As shown in Table 1 above, the deep defluorination synergistic Fenton catalytic materials of Examples 1 to 4 have better removal effects on fluoride and COD than the control experimental group. The reasons may be:

[0088] 1) The addition of dispersant prevents the agglomeration of aluminum atoms during the aging process.

[0089] 2) The modifier can react with the metal magnesium salt during the high-speed ball milling process, promoting the formation of magnesium peroxide in the lattice of the calcium-doped aluminum hydroxide precursor, and then forming magnesium-modified calcium-doped aluminum oxide nanomaterials.

[0090] 3) After magnesium peroxide modification, the metallic magnesium element can improve the stability and adsorption performance of the material.

[0091] 4) Magnesium peroxide can promote the Fenton reaction process to generate ·OH, thereby improving the material's ability to degrade organic pollutants.

[0092] 5) Cross-linking agents improve the strength and stability of the material. The deep defluorination synergistic Fenton catalytic material prepared with cross-linking agents has a larger specific surface area and porous structure, which improves the material's adsorption capacity for fluoride ions and the efficiency of free radical generation when degrading organic pollutants, thereby improving the material's removal effect on pollutants.

[0093] In addition, compared with Example 4, Examples 1 to 3 have better removal effects on fluoride and COD. The reason may be that the ratio of a certain component in Example 4 is not within the optimal ratio range, thereby affecting the performance of the prepared material.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above. For the sake of simplicity, they are not provided in detail. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a deep defluorination synergistic Fenton catalytic material, characterized in that: The steps include: Based on the first component, a calcium-doped aluminum hydroxide precursor is prepared by a precipitation method; Wherein, the first component for preparing the calcium-doped aluminum hydroxide precursor includes: aluminum-containing metal salt, pH value regulator, dispersant and calcium chloride; Based on the second component, magnesium-modified calcium-doped alumina nanomaterials were prepared by mechanical ball milling. Wherein, the second component for preparing the magnesium-modified calcium-doped aluminum oxide nanomaterial comprises: a magnesium metal salt, a modifier and the calcium-doped aluminum hydroxide precursor; Based on the third component, the deep defluorination synergistic Fenton catalytic material is prepared by a hydrothermal method; Wherein, the third component for preparing the deep defluorination synergistic Fenton catalytic material comprises: the magnesium-modified calcium-doped alumina nanomaterial, ammonium ferrous sulfate, thiourea and a cross-linking agent; The dispersant is selected from one or more of sodium tripolyphosphate, sodium hexametaphosphate and sodium pyrophosphate; The modifier is one or more of potassium ferrate, potassium permanganate and potassium superoxide; The cross-linking agent is one or more of cysteamine, tetravinylpentylamine, and polyoxypropylenediamine.

2. The preparation method according to claim 1, characterized in that The calcium-doped aluminum hydroxide precursor is prepared by a precipitation method based on the first component, specifically comprising: dissolving a preset weight of aluminum metal salt in deionized water to obtain an aluminum metal salt solution; Under stirring conditions, adding a pH adjuster dropwise to the aluminum metal salt solution to adjust the pH value to 10-11; After the pH value is adjusted, adding a preset weight of a dispersant, and adding a preset volume of a calcium chloride solution dropwise to obtain a first mixture; Stirring the first mixture at room temperature for a preset first time and allowing it to stand for a second time to obtain a first reactant; The first reactant is purified to obtain the calcium-doped aluminum hydroxide precursor.

3. The preparation method according to claim 2, characterized in that The preset weight of aluminum metal salt is: 5~10g of aluminum chloride; the deionized water is 50~100ml; the pH adjuster is ammonia water; the preset weight of dispersant is: 2~5g of sodium tripolyphosphate, sodium hexametaphosphate or sodium pyrophosphate; the preset volume of calcium chloride solution is: 20~50ml of 5~10% concentration calcium chloride solution.

4. The preparation method according to claim 1, characterized in that The magnesium-modified calcium-doped alumina nanomaterial is prepared by mechanical ball milling based on the second component, specifically comprising: uniformly mixing the calcium-doped aluminum hydroxide precursor, the magnesium metal salt, and the modifier in predetermined weights to obtain a second mixture; The second mixture is placed in a high-energy ball mill, and subjected to ball milling reaction at 2000 r / min to 3000 r / min for 1 to 4 hours to obtain the magnesium-modified calcium-doped alumina nanomaterial.

5. The preparation method according to claim 1, characterized in that The deep defluorination synergistic Fenton catalytic material is prepared by a hydrothermal method based on the third component, specifically comprising: adding a preset weight of magnesium-modified calcium-doped alumina nanomaterial to an ammonium ferrous sulfate solution, and adding a preset weight of thiourea and stirring to form a third mixture; Adding anhydrous ethanol dissolved with the cross-linking agent dropwise to the third mixture, and heating the mixture in a water bath to react, thereby obtaining a second reactant; Using a two-step calcination method on the second reactant to obtain the deep defluorination synergistic Fenton catalytic material; Wherein, the two-step calcination method comprises: calcining at a preset first temperature for 2 hours under a hydrogen reducing atmosphere; and Carbonization is performed at the preset second temperature for 2 hours.

6. The preparation method according to claim 5, characterized in that The preset weight of the magnesium-modified calcium-doped alumina nanomaterial is 5-10 g; the ammonium ferrous sulfate solution is 50-100 ml, a 5%-10% concentration of ammonium ferrous sulfate solution; and the preset weight of thiourea is 2-5 g of thiourea. The cross-linking agent is 1-5 g of cysteamine, tetravinylpentylamine or polyoxypropylenediamine; the anhydrous ethanol is 20-50 ml; and the heating reaction is carried out at 95-98° C. for 8-12 hours.

7. A deep defluorination synergistic Fenton catalytic material, characterized in that: The deep defluorination synergistic Fenton catalytic material is prepared by the preparation method according to any one of claims 1 to 6.

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