Fluorine-containing wastewater treatment method and treatment agent thereof

Abstract

The invention relates to a fluorine-containing wastewater treatment method and a fluorine-containing wastewater treatment agent, and relates to the technical field of fluorine-containing wastewater treatment.The fluorine-containing wastewater treatment agent is prepared from, by weight, 40-50 parts of MOFs / organic nanocrystalline / rare earth titanium dioxide composite materials, 20-25 parts of synergistic carriers, 15-20 parts of flocculation function and 10-15 parts of auxiliaries. The auxiliary agent is prepared by mixing nano zero-valent iron and montmorillonite according to a mass ratio of (5 to 8): 100. The treating agent is high in fluorine removal capacity, high in fluorine removal efficiency and stable in fluorine removal effect; the method for treating the fluorine-containing wastewater by adopting the treating agent is efficient, economical and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of fluorine-containing wastewater treatment, and in particular to a fluorine-containing wastewater treatment method and a treatment agent thereof. Background Art

[0002] With the rapid development of industry, the discharge of fluoride-containing wastewater is increasing. Fluoride-containing wastewater primarily originates from the chemical, metallurgical, electronic, and electroplating industries. If discharged without effective treatment, it poses serious risks to the environment and human health. Fluoride ions are difficult to degrade in the environment and can accumulate in organisms through the food chain, leading to various symptoms of fluoride poisoning. These symptoms can affect the normal development of bones and teeth, and cause diseases such as dental fluorosis and skeletal fluorosis. Therefore, timely treatment of fluoride-containing wastewater and ensuring that it meets discharge standards are challenges that companies producing fluoride wastewater must address.

[0003] Currently, treatment methods for fluoride-containing wastewater include precipitation, adsorption, electrocoagulation, electrodialysis, reverse osmosis, and ion exchange. Precipitation, which uses a chemical reaction to induce fluoride ions to form insoluble precipitates, is simple to operate, but can produce large amounts of chemical sludge and has limited efficiency at high fluoride concentrations. Adsorption, which utilizes the adsorption properties of specific materials such as activated carbon and zeolite to remove fluoride ions, offers flexibility and high adsorption efficiency, but the regeneration and disposal costs of the adsorbent materials are high, and their adsorption capacity is limited. Electrocoagulation, which utilizes an electrochemical reaction to generate a flocculant to promote fluoride flocculation and precipitation, offers high treatment efficiency, but consumes significant energy, and the loss and cost of electrode materials require additional consideration. Electrodialysis, which utilizes an electric field and a selectively permeable membrane to remove fluoride ions, is suitable for treating high-concentration fluoride wastewater, but suffers from high equipment investment and maintenance costs. Reverse osmosis, driven by high voltage, utilizes the highly selective removal of fluoride ions from a semipermeable membrane, offering high treatment efficiency but requiring stringent membrane material requirements and high operating costs. The ion exchange method uses ion exchange resin to exchange fluoride ions. It is easy to operate, but the regeneration and treatment costs of the resin are high.

[0004] To address the above-mentioned issues, a Chinese invention patent application with application publication number CN117247092A discloses a defluoridating agent for treating fluorine-containing wastewater and its preparation method. The defluoridating agent uses chitosan as a biomolecular skeleton and is prepared using magnesium salt, titanium salt, zirconium salt, aluminum salt, iron salt, rare earth material, and organic material as a blended raw material. The mass ratio of magnesium salt: titanium salt: zirconium salt: aluminum salt: iron salt: rare earth material: organic material: chitosan is 1-30:1-30:2-20:2-10:2-10:20-50:2-10:1-10. This invention adds magnesium salt, titanium salt, zirconium salt, and organic material to existing composite defluoridating agents to produce a new defluoridating agent. This defluoridating agent has good stability, a wide range of action, and is suitable for large-scale application. However, its treatment capacity for high-fluoride concentration wastewater is insufficient and its tolerance to complex coexisting ions is poor. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide an efficient, economical and environmentally friendly method for treating fluorine-containing wastewater and a treatment agent thereof, which has strong fluorine removal ability, high fluorine removal efficiency and stable fluorine removal effect.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a fluorine-containing wastewater treatment agent, comprising the following raw materials in parts by weight: 40-50 parts of MOFs / organic nanocrystals / rare earth titanium dioxide composite material, 20-25 parts of synergistic carrier, 15-20 parts of flocculation function, and 10-15 parts of auxiliary agent; the auxiliary agent is a mixture of nano zero-valent iron and montmorillonite in a mass ratio of (5-8):100.

[0007] Preferably, the preparation method of the MOFs / organic nanocrystal / rare earth titanium dioxide composite material comprises the following steps: Step D1, preparation of rare earth titanium dioxide: first, tetrabutyl titanate is slowly added to anhydrous ethanol and magnetically stirred for 25-35 minutes to form a uniform solution A; in another beaker, glacial acetic acid, deionized water, and a mixed solution of lanthanum nitrate and cerium nitrate are added and stirred uniformly to form solution B; solution B is added dropwise to solution A while magnetically stirring for 1-2 hours to complete the dripping, and then stirring is continued for 2-3 hours to form a stable sol; the sol is allowed to stand and age at room temperature for 24 hours to form a gel, and the gel is then placed in an oven and dried at 60-70°C for 10-14 hours; finally, the temperature is raised to 500-550°C at a rate of 3-5°C / minute, kept at this temperature for calcination for 2-4 hours, and naturally cooled to room temperature to obtain rare earth titanium dioxide; Step D2, Preparation of Organic Nanocrystal / Rare Earth Titanium Dioxide Composite Material: Disperse cellulose nanocrystals in deionized water, add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide as activators, and stir at room temperature for 0.8-1.2 hours; then add the rare earth titanium dioxide prepared in step S1, stir and react at 60°C for 4 hours, centrifuge and wash, and vacuum dry at 60°C for 12 hours to obtain an organic nanocrystal / rare earth titanium dioxide composite material; Step D3, preparation of MOFs / organic nanocrystal / rare earth titanium dioxide composite material: ZrCl4 and 2-aminoterephthalic acid were dissolved in N,N-dimethylformamide, and the organic nanocrystal modified / rare earth titanium dioxide composite material prepared in step S2 was added. After ultrasonic dispersion for 25-35 minutes, the mixture was transferred to a hydrothermal autoclave and reacted at 118-122°C for 22-25 hours. The product was washed alternately with N,N-dimethylformamide and ethanol three times and vacuum dried at 70-80°C for 10-15 hours to obtain a MOFs / organic nanocrystal / rare earth titanium dioxide composite material.

[0008] Preferably, the volume ratio of tetrabutyl titanate, anhydrous ethanol, glacial acetic acid and deionized water in step D1 is 4:10:1:1.

[0009] Preferably, the molar ratio of tetrabutyl titanate, lanthanum nitrate and cerium nitrate in step D1 is 1:0.02:0.04.

[0010] Preferably, the mass ratio of the cellulose nanocrystals, deionized water, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, and rare earth titanium dioxide in step D2 is 1:200:0.2:0.2:10.

[0011] Preferably, the cellulose nanocrystals in step D2 have a diameter of 10-50 nm and a length of 200-500 nm.

[0012] Preferably, the amount ratio of ZrCl4, 2-aminoterephthalic acid, N,N-dimethylformamide, and organic nanocrystal modified / rare earth titanium dioxide composite material in step D3 is 0.5 mmol: 0.5 mmol: 50 mL: 1 g.

[0013] Preferably, the synergistic carrier is a mixture of attapulgite and hydroxyapatite in a mass ratio of (2-3):1.

[0014] Preferably, the average particle size of the hydroxyapatite is 1-5 μm; the average particle size of the attapulgite is 5-20 μm.

[0015] Preferably, the flocculation function is a mixture of polyaluminum ferric chloride and modified starch acrylamide copolymer in a mass ratio of 1: (0.8-1.2).

[0016] Preferably, the polyaluminium ferric chloride is SJ-601 polyaluminium ferric chloride PAFC-A2 type; there is no special requirement for the source of the modified starch acrylamide copolymer. In one embodiment of the present invention, the modified starch acrylamide copolymer is prepared according to the method of Example 11 of the Chinese invention patent with authorization publication number CN102936318B.

[0017] Preferably, the particle size of the nano zero-valent iron is 20-30 nm; the particle size of the montmorillonite is 1-5 μm.

[0018] Another object of the present invention is to provide a method for treating fluorine-containing wastewater using the above-mentioned fluorine-containing wastewater treatment agent, comprising the following steps: collecting the fluorine-containing wastewater into a reaction tank, and adjusting the pH value of the wastewater to 6-8 by adding sodium hydroxide solution; after adding the treatment agent, performing two-stage stirring, the first stage is rapid stirring, with a rotation speed of 300-400 r / min and a stirring time of 5-10 minutes, so that the agent and the wastewater are fully mixed; the second stage is slow stirring, with a rotation speed of 50-100 r / min and a stirring time of 20-30 minutes, to promote floc formation; the mixed liquid after the reaction is sent to an inclined tube sedimentation tank for a residence time of 1-2 hours, the supernatant is the treated water, and the bottom sludge is dehydrated by a plate and frame filter press and then transported for disposal.

[0019] Preferably, the ratio of the added mass of the treatment agent to the mass of fluoride ions in the wastewater is (1.2-2.0):1.

[0020] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The method for treating fluorine-containing wastewater disclosed in the present invention has simple process, convenient construction, high efficiency, low dependence on equipment, and high promotion and application value.

[0021] (2) The fluorine-containing wastewater treatment agent disclosed in the present invention comprises the following raw materials, calculated by weight: 40-50 parts of a MOFs / organic nanocrystal / rare earth titanium dioxide composite material, 20-25 parts of a synergistic carrier, 15-20 parts of a flocculating agent, and 10-15 parts of an auxiliary agent; the auxiliary agent is a mixture of nano-zero-valent iron and montmorillonite in a mass ratio of (5-8):100. Through the mutual coordination and joint action of the raw materials, the prepared treatment agent has a strong fluorine removal capacity, high fluorine removal efficiency, and stable fluorine removal effect; the method for treating fluorine-containing wastewater using the treatment agent is efficient, economical, and environmentally friendly.

[0022] (3) The fluorine-containing wastewater treatment agent disclosed in this invention is the first to have an "organic nanocrystal-MOFs-rare earth" trinity enhanced structure. The introduction of organic nanocrystals not only increases the specific surface area of ​​the material, but also the abundant hydroxyl groups on their surface can form additional hydrogen bonds with F⁻, forming a synergistic relationship with the adsorption sites of MOFs and rare earth ions, significantly improving the saturated adsorption capacity. At the same time, the organic nanocrystals act as a bridge, strengthening the binding force between MOFs and rare earth titanium dioxide, making the material more structurally stable during recycling. (4) The fluorine-containing wastewater treatment agent disclosed in the present invention establishes a multi-stage purification model of "multiple adsorption-enhanced coordination-efficient flocculation". The small size effect of organic nanocrystals enables them to enter the pores of MOFs, forming an adsorption network and improving the capture efficiency of F⁻; rare earth ions firmly fix the adsorbed F⁻ through coordination to prevent desorption; and the attapulgite-hydroxyapatite carrier provides a flocculation framework. The three factors work together to significantly improve the fluorine removal efficiency compared to materials without organic nanocrystals. Compared with using MOFs or organic nanocrystals alone, the solid-liquid separation efficiency of the composite material is significantly improved, solving the problem of difficult recycling of nanomaterials.

[0023] (5) The fluorine-containing wastewater treatment agent disclosed in the present invention has an auxiliary phase (10-15 parts) of a composite system of nano-zero-valent iron and montmorillonite (mass ratio 5-8:100). Nano-zero-valent iron (particle size 20-30nm) not only removes oxidative interfering substances (such as Cr) in water through reduction, but also removes oxidative interfering substances (such as Cr) in water through reduction. 6 ⁺), its surface Fe 2 ⁺ It also forms complexes with fluoride ions, while the layered structure of montmorillonite (particle size 1-5μm) immobilizes nano-zero-valent iron, reducing agglomeration losses. This combination significantly reduces sludge production and significantly lowers sludge disposal costs. DETAILED DESCRIPTION

[0024] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are merely examples, and those skilled in the art may conceive of other obvious variations.

[0025] Example 1 A fluorine-containing wastewater treatment agent comprises the following raw materials in parts by weight: 40 parts of a MOFs / organic nanocrystal / rare earth titanium dioxide composite material, 20 parts of a synergistic carrier, 15 parts of a flocculation function, and 10 parts of an auxiliary agent; the auxiliary agent is a mixture of nano-zero-valent iron and montmorillonite in a mass ratio of 5:100.

[0026] The preparation method of the MOFs / organic nanocrystal / rare earth titanium dioxide composite material comprises the following steps: Step D1, Preparation of Rare Earth Titanium Dioxide: Tetrabutyl Titanate was first slowly added to anhydrous ethanol and magnetically stirred for 25 minutes to form a uniform solution A; glacial acetic acid, deionized water, and a mixed solution of lanthanum nitrate and cerium nitrate were added to another beaker and stirred uniformly to form solution B; solution B was added dropwise to solution A while magnetically stirring for 1 hour, and then stirred for 2 hours to form a stable sol; the sol was allowed to stand and age at room temperature for 24 hours to form a gel, and the gel was then placed in an oven and dried at 60°C for 10 hours; finally, the temperature was raised to 500°C at a rate of 3°C / min, calcined at this temperature for 2 hours, and naturally cooled to room temperature to obtain rare earth titanium dioxide; Step D2, Preparation of Organic Nanocrystal / Rare Earth Titanium Dioxide Composite Material: Cellulose nanocrystals were dispersed in deionized water, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide were added as activators, and the mixture was stirred at room temperature for 0.8 h; then, the rare earth titanium dioxide prepared in step S1 was added, stirred at 60° C. for 4 h, and after centrifugal washing, vacuum drying at 60° C. for 12 h was performed to obtain an organic nanocrystal / rare earth titanium dioxide composite material; Step D3, preparation of MOFs / organic nanocrystals / rare earth titanium dioxide composite material: ZrCl4 and 2-aminoterephthalic acid were dissolved in N,N-dimethylformamide, and the organic nanocrystal modified / rare earth titanium dioxide composite material prepared in step S2 was added. After ultrasonic dispersion for 25 minutes, the mixture was transferred to a hydrothermal autoclave and reacted at 118°C for 22 hours. The product was washed alternately with N,N-dimethylformamide and ethanol three times and vacuum dried at 70°C for 10 hours to obtain a MOFs / organic nanocrystal / rare earth titanium dioxide composite material.

[0027] The volume ratio of tetrabutyl titanate, anhydrous ethanol, glacial acetic acid, and deionized water in step D1 is 4:10:1:1; the molar ratio of tetrabutyl titanate, lanthanum nitrate, and cerium nitrate in step D1 is 1:0.02:0.04; the mass ratio of cellulose nanocrystals, deionized water, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, and rare earth titanium dioxide in step D2 is 1:200:0.2:0.2:10; the diameter of the cellulose nanocrystals in step D2 is 10-50 nm and the length is 200-500 nm; the molar ratio of ZrCl4, 2-aminoterephthalic acid, N,N-dimethylformamide, and organic nanocrystal-modified / rare earth titanium dioxide composite material in step D3 is 0.5 mmol:0.5 mmol:50 mL:1 g.

[0028] The synergistic carrier is a mixture of attapulgite and hydroxyapatite in a mass ratio of 2:1; the average particle size of the hydroxyapatite is 1 μm; the average particle size of the attapulgite is 5 μm; the flocculation function is a mixture of polyaluminum ferric chloride and modified starch acrylamide copolymer in a mass ratio of 1:0.8; the polyaluminum ferric chloride is SJ-601 polyaluminum ferric chloride PAFC-A2 type; the modified starch acrylamide copolymer is prepared according to the method of Example 11 of the Chinese invention patent with authorization announcement number CN102936318B; the particle size of the nano zero-valent iron is 20-30 nm; the particle size of the montmorillonite is 1-5 μm.

[0029] A method for treating fluorine-containing wastewater by using the fluorine-containing wastewater treatment agent comprises the following steps: collecting the fluorine-containing wastewater into a reaction tank, and adjusting the pH value of the wastewater to 6 by adding a sodium hydroxide solution; after adding the treatment agent, performing two-stage stirring, wherein the first stage is rapid stirring with a rotation speed of 300 r / min and a stirring time of 5 minutes, so as to fully mix the agent and the wastewater; and the second stage is slow stirring with a rotation speed of 50 r / min and a stirring time of 20 minutes, so as to promote floc formation; the mixed liquid after the reaction is sent to an inclined tube sedimentation tank with a residence time of 1 hour, the supernatant is the treated water, and the bottom sludge is dehydrated by a plate and frame filter press and then transported for disposal; the ratio of the added mass of the treatment agent to the mass of fluoride ions in the wastewater is 1.2:1.

[0030] Example 2 A fluorine-containing wastewater treatment agent comprises the following raw materials in parts by weight: 43 parts of a MOFs / organic nanocrystal / rare earth titanium dioxide composite material, 21 parts of a synergistic carrier, 16 parts of a flocculation function, and 11 parts of an auxiliary agent; the auxiliary agent is a mixture of nano-zero-valent iron and montmorillonite in a mass ratio of 6:100.

[0031] The preparation method of the MOFs / organic nanocrystal / rare earth titanium dioxide composite material comprises the following steps: Step D1, preparation of rare earth titanium dioxide: first, tetrabutyl titanate was slowly added to anhydrous ethanol and magnetically stirred for 27 minutes to form a uniform solution A; in another beaker, glacial acetic acid, deionized water, and a mixed solution of lanthanum nitrate and cerium nitrate were added and stirred uniformly to form solution B; solution B was added dropwise to solution A while magnetically stirring for 1.2 hours, and then stirred for 2.3 hours to form a stable sol; the sol was allowed to stand and age at room temperature for 24 hours to form a gel, and then the gel was placed in an oven and dried at 63°C for 11 hours; finally, the temperature was raised to 520°C at a rate of 3.5°C / min, calcined at this temperature for 2.5 hours, and naturally cooled to room temperature to obtain rare earth titanium dioxide; Step D2, Preparation of Organic Nanocrystal / Rare Earth Titanium Dioxide Composite Material: Cellulose nanocrystals were dispersed in deionized water, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide were added as activators, and the mixture was stirred at room temperature for 0.9 h; then, the rare earth titanium dioxide prepared in step S1 was added, stirred at 60° C. for 4 h, and then centrifuged and washed, and vacuum dried at 60° C. for 12 h to obtain an organic nanocrystal / rare earth titanium dioxide composite material; Step D3, preparation of MOFs / organic nanocrystals / rare earth titanium dioxide composite material: ZrCl4 and 2-aminoterephthalic acid were dissolved in N,N-dimethylformamide, and the organic nanocrystal modified / rare earth titanium dioxide composite material prepared in step S2 was added. After ultrasonic dispersion for 27 minutes, the mixture was transferred to a hydrothermal autoclave and reacted at 119°C for 23 hours. The product was washed alternately with N,N-dimethylformamide and ethanol three times and vacuum dried at 73°C for 12 hours to obtain a MOFs / organic nanocrystal / rare earth titanium dioxide composite material.

[0032] The volume ratio of tetrabutyl titanate, anhydrous ethanol, glacial acetic acid, and deionized water in step D1 is 4:10:1:1; the molar ratio of tetrabutyl titanate, lanthanum nitrate, and cerium nitrate in step D1 is 1:0.02:0.04; the mass ratio of cellulose nanocrystals, deionized water, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, and rare earth titanium dioxide in step D2 is 1:200:0.2:0.2:10; the diameter of the cellulose nanocrystals in step D2 is 10-50 nm and the length is 200-500 nm; the molar ratio of ZrCl4, 2-aminoterephthalic acid, N,N-dimethylformamide, and organic nanocrystal-modified / rare earth titanium dioxide composite material in step D3 is 0.5 mmol:0.5 mmol:50 mL:1 g.

[0033] The synergistic carrier is a mixture of attapulgite and hydroxyapatite in a mass ratio of 2.3:1; the average particle size of the hydroxyapatite is 2 μm; the average particle size of the attapulgite is 8 μm; the flocculation function is a mixture of polyaluminum ferric chloride and modified starch acrylamide copolymer in a mass ratio of 1:0.9; the polyaluminum ferric chloride is SJ-601 polyaluminum ferric chloride PAFC-A2 type; the modified starch acrylamide copolymer is prepared according to the method of Example 11 of the Chinese invention patent with authorization announcement number CN102936318B; the particle size of the nano zero-valent iron is 20-30 nm; the particle size of the montmorillonite is 1-5 μm.

[0034] A method for treating fluorine-containing wastewater by using the above-mentioned fluorine-containing wastewater treatment agent comprises the following steps: collecting the fluorine-containing wastewater into a reaction tank, and adjusting the pH value of the wastewater to 6.5 by adding a sodium hydroxide solution; after adding the treatment agent, performing two-stage stirring, wherein the first stage is rapid stirring with a rotation speed of 330 r / min and a stirring time of 7 minutes, so that the agent and the wastewater are fully mixed; and the second stage is slow stirring with a rotation speed of 70 r / min and a stirring time of 23 minutes, so as to promote floc formation; the mixed liquid after the reaction is sent to an inclined tube sedimentation tank with a residence time of 1.2 hours, the supernatant is the treated water, and the bottom sludge is dehydrated by a plate and frame filter press and then transported for disposal; the ratio of the added mass of the treatment agent to the mass of fluoride ions in the wastewater is 1.2:1.

[0035] Example 3 A fluorine-containing wastewater treatment agent comprises the following raw materials in parts by weight: 45 parts of a MOFs / organic nanocrystal / rare earth titanium dioxide composite material, 23 parts of a synergistic carrier, 18 parts of a flocculating agent, and 13 parts of an auxiliary agent; the auxiliary agent is a mixture of nano-zero-valent iron and montmorillonite in a mass ratio of 6.5:100.

[0036] The preparation method of the MOFs / organic nanocrystal / rare earth titanium dioxide composite material comprises the following steps: Step D1, preparation of rare earth titanium dioxide: first, tetrabutyl titanate is slowly added to anhydrous ethanol and magnetically stirred for 30 minutes to form a uniform solution A; in another beaker, glacial acetic acid, deionized water, and a mixed solution of lanthanum nitrate and cerium nitrate are added and stirred uniformly to form solution B; solution B is added dropwise to solution A while magnetically stirring for 1.5 hours, and then stirred for 2.5 hours to form a stable sol; the sol is allowed to stand and age at room temperature for 24 hours to form a gel, and the gel is then placed in an oven and dried at 65°C for 12.5 hours; finally, the temperature is raised to 530°C at a rate of 4°C / min, kept at this temperature for calcination for 3 hours, and naturally cooled to room temperature to obtain rare earth titanium dioxide; Step D2, Preparation of Organic Nanocrystal / Rare Earth Titanium Dioxide Composite Material: Cellulose nanocrystals were dispersed in deionized water, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide were added as activators, and the mixture was stirred at room temperature for 1 hour; then, the rare earth titanium dioxide prepared in step S1 was added, stirred at 60°C for 4 hours, and the mixture was centrifuged and washed, and then vacuum-dried at 60°C for 12 hours to obtain an organic nanocrystal / rare earth titanium dioxide composite material; Step D3, preparation of MOFs / organic nanocrystals / rare earth titanium dioxide composite material: ZrCl4 and 2-aminoterephthalic acid were dissolved in N,N-dimethylformamide, and the organic nanocrystal modified / rare earth titanium dioxide composite material prepared in step S2 was added. After ultrasonic dispersion for 30 minutes, the mixture was transferred to a hydrothermal autoclave and reacted at 120°C for 23.5 hours. The product was washed alternately with N,N-dimethylformamide and ethanol three times and vacuum dried at 75°C for 13 hours to obtain a MOFs / organic nanocrystal / rare earth titanium dioxide composite material.

[0037] The volume ratio of tetrabutyl titanate, anhydrous ethanol, glacial acetic acid, and deionized water in step D1 is 4:10:1:1; the molar ratio of tetrabutyl titanate, lanthanum nitrate, and cerium nitrate in step D1 is 1:0.02:0.04; the mass ratio of cellulose nanocrystals, deionized water, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, and rare earth titanium dioxide in step D2 is 1:200:0.2:0.2:10; the diameter of the cellulose nanocrystals in step D2 is 10-50 nm and the length is 200-500 nm; the molar ratio of ZrCl4, 2-aminoterephthalic acid, N,N-dimethylformamide, and organic nanocrystal-modified / rare earth titanium dioxide composite material in step D3 is 0.5 mmol:0.5 mmol:50 mL:1 g.

[0038] The synergistic carrier is a mixture of attapulgite and hydroxyapatite in a mass ratio of 2.5:1; the average particle size of the hydroxyapatite is 3.5 μm; the average particle size of the attapulgite is 13 μm; the flocculation function is a mixture of polyaluminum ferric chloride and modified starch acrylamide copolymer in a mass ratio of 1:1; the polyaluminum ferric chloride is SJ-601 polyaluminum ferric chloride PAFC-A2 type; the modified starch acrylamide copolymer is prepared according to the method of Example 11 of the Chinese invention patent with authorization announcement number CN102936318B; the particle size of the nano zero-valent iron is 20-30 nm; the particle size of the montmorillonite is 1-5 μm.

[0039] A method for treating fluorine-containing wastewater by using the above-mentioned fluorine-containing wastewater treatment agent comprises the following steps: collecting the fluorine-containing wastewater into a reaction tank, and adjusting the pH value of the wastewater to 7 by adding a sodium hydroxide solution; after adding the treatment agent, performing two-stage stirring, wherein the first stage is rapid stirring with a rotation speed of 350 r / min and a stirring time of 7 minutes, so that the agent and the wastewater are fully mixed; and the second stage is slow stirring with a rotation speed of 80 r / min and a stirring time of 25 minutes, so as to promote floc formation; the mixed liquid after the reaction is sent to an inclined tube sedimentation tank with a residence time of 1.5 hours, the supernatant is the treated water, and the bottom sludge is dehydrated by a plate and frame filter press and then transported for disposal; the ratio of the added mass of the treatment agent to the mass of fluoride ions in the wastewater is 1.6:1.

[0040] Example 4 A fluorine-containing wastewater treatment agent comprises the following raw materials in parts by weight: 48 parts of a MOFs / organic nanocrystal / rare earth titanium dioxide composite material, 24 parts of a synergistic carrier, 19 parts of a flocculation function, and 14 parts of an auxiliary agent; the auxiliary agent is a mixture of nano-zero-valent iron and montmorillonite in a mass ratio of 7.5:100.

[0041] The preparation method of the MOFs / organic nanocrystal / rare earth titanium dioxide composite material comprises the following steps: Step D1, preparation of rare earth titanium dioxide: first, tetrabutyl titanate was slowly added to anhydrous ethanol and magnetically stirred for 33 minutes to form a uniform solution A; glacial acetic acid, deionized water, and a mixed solution of lanthanum nitrate and cerium nitrate were added to another beaker and stirred uniformly to form solution B; solution B was added dropwise to solution A while magnetically stirring for 1.8 hours, and then stirred for 2.8 hours to form a stable sol; the sol was allowed to stand and age at room temperature for 24 hours to form a gel, and then the gel was placed in an oven and dried at 68°C for 13.5 hours; finally, the temperature was raised to 540°C at a rate of 4.5°C / min, calcined at this temperature for 3.5 hours, and naturally cooled to room temperature to obtain rare earth titanium dioxide; Step D2, Preparation of Organic Nanocrystal / Rare Earth Titanium Dioxide Composite Material: Cellulose nanocrystals were dispersed in deionized water, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide were added as activators, and the mixture was stirred at room temperature for 1.1 hours; then, the rare earth titanium dioxide prepared in step S1 was added, stirred at 60°C for 4 hours, and the mixture was centrifuged and washed, and then vacuum dried at 60°C for 12 hours to obtain an organic nanocrystal / rare earth titanium dioxide composite material; Step D3, preparation of MOFs / organic nanocrystals / rare earth titanium dioxide composite material: ZrCl4 and 2-aminoterephthalic acid were dissolved in N,N-dimethylformamide, and the organic nanocrystal modified / rare earth titanium dioxide composite material prepared in step S2 was added. After ultrasonic dispersion for 33 minutes, the mixture was transferred to a hydrothermal autoclave and reacted at 121°C for 24.5 hours. The product was washed alternately with N,N-dimethylformamide and ethanol three times and vacuum dried at 78°C for 14 hours to obtain a MOFs / organic nanocrystal / rare earth titanium dioxide composite material.

[0042] The volume ratio of tetrabutyl titanate, anhydrous ethanol, glacial acetic acid, and deionized water in step D1 is 4:10:1:1; the molar ratio of tetrabutyl titanate, lanthanum nitrate, and cerium nitrate in step D1 is 1:0.02:0.04; the mass ratio of cellulose nanocrystals, deionized water, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, and rare earth titanium dioxide in step D2 is 1:200:0.2:0.2:10; the diameter of the cellulose nanocrystals in step D2 is 10-50 nm and the length is 200-500 nm; the molar ratio of ZrCl4, 2-aminoterephthalic acid, N,N-dimethylformamide, and organic nanocrystal-modified / rare earth titanium dioxide composite material in step D3 is 0.5 mmol:0.5 mmol:50 mL:1 g.

[0043] The synergistic carrier is a mixture of attapulgite and hydroxyapatite in a mass ratio of 2.8:1; the average particle size of the hydroxyapatite is 4 μm; the average particle size of the attapulgite is 18 μm; the flocculation function is a mixture of polyaluminum ferric chloride and modified starch acrylamide copolymer in a mass ratio of 1:1.1; the polyaluminum ferric chloride is SJ-601 polyaluminum ferric chloride PAFC-A2 type; the modified starch acrylamide copolymer is prepared according to the method of Example 11 of the Chinese invention patent with authorization announcement number CN102936318B; the particle size of the nano zero-valent iron is 20-30 nm; the particle size of the montmorillonite is 1-5 μm.

[0044] A method for treating fluorine-containing wastewater by using the above-mentioned fluorine-containing wastewater treatment agent comprises the following steps: collecting the fluorine-containing wastewater into a reaction tank, and adjusting the pH value of the wastewater to 7.5 by adding a sodium hydroxide solution; after adding the treatment agent, performing two-stage stirring, wherein the first stage is rapid stirring with a rotation speed of 390 r / min and a stirring time of 9 minutes, so that the agent and the wastewater are fully mixed; and the second stage is slow stirring with a rotation speed of 90 r / min and a stirring time of 28 minutes, so as to promote floc formation; the mixed liquid after the reaction is sent to an inclined tube sedimentation tank with a residence time of 1.8 hours, the supernatant is the treated water, and the bottom sludge is dehydrated by a plate and frame filter press and then transported for disposal; the ratio of the added mass of the treatment agent to the mass of fluoride ions in the wastewater is 1.2:1.

[0045] Example 5 A fluorine-containing wastewater treatment agent comprises the following raw materials in parts by weight: 50 parts of a MOFs / organic nanocrystal / rare earth titanium dioxide composite material, 25 parts of a synergistic carrier, 20 parts of a flocculation function, and 15 parts of an auxiliary agent; the auxiliary agent is a mixture of nano-zero-valent iron and montmorillonite in a mass ratio of 8:100.

[0046] The preparation method of the MOFs / organic nanocrystal / rare earth titanium dioxide composite material comprises the following steps: Step D1, preparation of rare earth titanium dioxide: first, tetrabutyl titanate is slowly added to anhydrous ethanol and magnetically stirred for 35 minutes to form a uniform solution A; in another beaker, glacial acetic acid, deionized water, and a mixed solution of lanthanum nitrate and cerium nitrate are added and stirred uniformly to form solution B; solution B is added dropwise to solution A while magnetically stirring for 2 hours, and then stirred for 3 hours to form a stable sol; the sol is allowed to stand and age at room temperature for 24 hours to form a gel, and the gel is then placed in an oven and dried at 70°C for 14 hours; finally, the temperature is raised to 550°C at a rate of 5°C / min, calcined at this temperature for 4 hours, and naturally cooled to room temperature to obtain rare earth titanium dioxide; Step D2, Preparation of Organic Nanocrystal / Rare Earth Titanium Dioxide Composite Material: Cellulose nanocrystals were dispersed in deionized water, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide were added as activators, and the mixture was stirred at room temperature for 1.2 hours; then, the rare earth titanium dioxide prepared in step S1 was added, stirred at 60°C for 4 hours, and the mixture was centrifuged and washed, and then vacuum-dried at 60°C for 12 hours to obtain an organic nanocrystal / rare earth titanium dioxide composite material; Step D3, preparation of MOFs / organic nanocrystals / rare earth titanium dioxide composite material: ZrCl4 and 2-aminoterephthalic acid were dissolved in N,N-dimethylformamide, and the organic nanocrystal modified / rare earth titanium dioxide composite material prepared in step S2 was added. After ultrasonic dispersion for 35 minutes, the mixture was transferred to a hydrothermal autoclave and reacted at 122°C for 25 hours. The product was washed alternately with N,N-dimethylformamide and ethanol three times and vacuum dried at 80°C for 15 hours to obtain a MOFs / organic nanocrystal / rare earth titanium dioxide composite material.

[0047] The volume ratio of tetrabutyl titanate, anhydrous ethanol, glacial acetic acid, and deionized water in step D1 is 4:10:1:1; the molar ratio of tetrabutyl titanate, lanthanum nitrate, and cerium nitrate in step D1 is 1:0.02:0.04; the mass ratio of cellulose nanocrystals, deionized water, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, and rare earth titanium dioxide in step D2 is 1:200:0.2:0.2:10; the diameter of the cellulose nanocrystals in step D2 is 10-50 nm and the length is 200-500 nm; the molar ratio of ZrCl4, 2-aminoterephthalic acid, N,N-dimethylformamide, and organic nanocrystal-modified / rare earth titanium dioxide composite material in step D3 is 0.5 mmol:0.5 mmol:50 mL:1 g.

[0048] The synergistic carrier is a mixture of attapulgite and hydroxyapatite in a mass ratio of 3:1; the average particle size of the hydroxyapatite is 5 μm; the average particle size of the attapulgite is 20 μm; the flocculation function is a mixture of polyaluminum ferric chloride and modified starch acrylamide copolymer in a mass ratio of 1:1.2; the polyaluminum ferric chloride is SJ-601 polyaluminum ferric chloride PAFC-A2 type; the modified starch acrylamide copolymer is prepared according to the method of Example 11 of the Chinese invention patent with authorization announcement number CN102936318B; the particle size of the nano zero-valent iron is 20-30 nm; the particle size of the montmorillonite is 1-5 μm.

[0049] A method for treating fluorine-containing wastewater by using the above-mentioned fluorine-containing wastewater treatment agent comprises the following steps: collecting the fluorine-containing wastewater into a reaction tank, and adjusting the pH value of the wastewater to 8 by adding a sodium hydroxide solution; after adding the treatment agent, performing two-stage stirring, wherein the first stage is rapid stirring with a rotation speed of 400 r / min and a stirring time of 10 minutes, so that the agent and the wastewater are fully mixed; and the second stage is slow stirring with a rotation speed of 100 r / min and a stirring time of 30 minutes, so as to promote floc formation; the mixed liquid after the reaction is sent to an inclined tube sedimentation tank with a residence time of 2 hours, the supernatant is the treated water, and the bottom sludge is dehydrated by a plate and frame filter press and then transported for disposal; the ratio of the added mass of the treatment agent to the mass of fluoride ions in the wastewater is 1.2:1.

[0050] Comparative Example 1 This example provides a fluorine-containing wastewater treatment method and treatment agent, which are basically the same as Example 1, except that an equal amount of rare earth titanium dioxide is used instead of the MOFs / organic nanocrystal / rare earth titanium dioxide composite material.

[0051] Comparative Example 2 This example provides a fluorine-containing wastewater treatment method and treatment agent, which are basically the same as Example 1, except that an equal amount of polyaluminum ferric chloride is used instead of the modified starch acrylamide copolymer.

[0052] In order to further illustrate the beneficial technical effects of the fluorine-containing wastewater treatment method and the treatment agent involved in each embodiment of the present invention, the following experiments were conducted on each product and its use method: Fluoride-containing wastewater from an electronic component production workshop in Inner Mongolia was treated according to the methods described in Examples 1-5 and Comparative Examples 1-2. The fluoride ion concentration in the treated water was measured, and the fluoride removal rate was calculated. The fluoride ion concentration was determined according to HJ 84-2016, "Water Quality—Determination of Inorganic Anions—Ion Chromatography Method." The test results are shown in Table 1.

[0053] As can be seen from Table 1, the fluorine-containing wastewater treatment methods and treatment agents disclosed in the embodiments of the present invention have better fluorine-containing wastewater treatment effects than the comparative examples. The combined use of MOFs / organic nanocrystals / rare earth titanium dioxide composite materials, polyaluminum ferric chloride and modified starch acrylamide copolymer is beneficial to improving the above-mentioned properties.

[0054] Table 1

[0055] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A fluorine-containing wastewater treatment agent, characterized in that The invention comprises the following raw materials in parts by weight: 40-50 parts of MOFs / organic nanocrystals / rare earth titanium dioxide composite material, 20-25 parts of synergistic carrier, 15-20 parts of flocculation function, and 10-15 parts of auxiliary agent; the auxiliary agent is a mixture of nano zero-valent iron and montmorillonite in a mass ratio of (5-8):

100.

2. The fluorine-containing wastewater treatment agent according to claim 1, characterized in that The preparation method of the MOFs / organic nanocrystal / rare earth titanium dioxide composite material comprises the following steps: Step D1, preparation of rare earth titanium dioxide: first, tetrabutyl titanate is slowly added to anhydrous ethanol and magnetically stirred for 25-35 minutes to form a uniform solution A; in another beaker, glacial acetic acid, deionized water, and a mixed solution of lanthanum nitrate and cerium nitrate are added and stirred uniformly to form solution B; solution B is added dropwise to solution A while magnetically stirring for 1-2 hours to complete the dripping, and then stirring is continued for 2-3 hours to form a stable sol; the sol is allowed to stand and age at room temperature for 24 hours to form a gel, and the gel is then placed in an oven and dried at 60-70°C for 10-14 hours; finally, the temperature is raised to 500-550°C at a rate of 3-5°C / minute, kept at this temperature for calcination for 2-4 hours, and naturally cooled to room temperature to obtain rare earth titanium dioxide; Step D2, Preparation of Organic Nanocrystal / Rare Earth Titanium Dioxide Composite Material: Disperse cellulose nanocrystals in deionized water, add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide as activators, and stir at room temperature for 0.8-1.2 hours; then add the rare earth titanium dioxide prepared in step S1, stir and react at 60°C for 4 hours, centrifuge and wash, and vacuum dry at 60°C for 12 hours to obtain an organic nanocrystal / rare earth titanium dioxide composite material; Step D3, preparation of MOFs / organic nanocrystal / rare earth titanium dioxide composite material: ZrCl4 and 2-aminoterephthalic acid were dissolved in N,N-dimethylformamide, and the organic nanocrystal modified / rare earth titanium dioxide composite material prepared in step S2 was added. After ultrasonic dispersion for 25-35 minutes, the mixture was transferred to a hydrothermal autoclave and reacted at 118-122°C for 22-25 hours. The product was washed alternately with N,N-dimethylformamide and ethanol three times and vacuum dried at 70-80°C for 10-15 hours to obtain a MOFs / organic nanocrystal / rare earth titanium dioxide composite material.

3. The fluorine-containing wastewater treatment agent according to claim 2, characterized in that The volume ratio of tetrabutyl titanate, anhydrous ethanol, glacial acetic acid, and deionized water in step D1 is 4:10:1:

1.

4. The fluorine-containing wastewater treatment agent according to claim 2, characterized in that The molar ratio of tetrabutyl titanate, lanthanum nitrate and cerium nitrate in step D1 is 1:0.02:0.

04.

5. The fluorine-containing wastewater treatment agent according to claim 2, characterized in that The mass ratio of the cellulose nanocrystals, deionized water, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, and rare earth titanium dioxide in step D2 is 1:200:0.2:0.2:10; the diameter of the cellulose nanocrystals in step D2 is 10-50 nm and the length is 200-500 nm.

6. The fluorine-containing wastewater treatment agent according to claim 2, characterized in that The amount ratio of ZrCl4, 2-aminoterephthalic acid, N,N-dimethylformamide, and organic nanocrystal modified / rare earth titanium dioxide composite material in step D3 is 0.5mmol:0.5mmol:50mL:1g.

7. The fluorine-containing wastewater treatment agent according to claim 1, characterized in that The synergistic carrier is prepared by mixing attapulgite and hydroxyapatite in a mass ratio of (2-3):

1.

8. The fluorine-containing wastewater treatment agent according to claim 7, characterized in that The average particle size of the hydroxyapatite is 1-5 μm; the average particle size of the attapulgite is 5-20 μm.

9. The fluorine-containing wastewater treatment agent according to claim 1, characterized in that The flocculation function is a mixture of polyaluminum ferric chloride and modified starch acrylamide copolymer in a mass ratio of 1: (0.8-1.2); the polyaluminum ferric chloride is SJ-601 polyaluminum ferric chloride PAFC-A2 type; the particle size of the nano zero-valent iron is 20-30nm; the particle size of the montmorillonite is 1-5μm.

10. A method for treating fluorine-containing wastewater using the fluorine-containing wastewater treating agent according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: collecting fluorine-containing wastewater into a reaction tank, adjusting the pH value of the wastewater to 6-8 by adding a sodium hydroxide solution; after adding a treatment agent, performing two-stage stirring, wherein the first stage is rapid stirring at a speed of 300-400 r / min and a stirring time of 5-10 minutes to fully mix the agent with the wastewater; The second stage is slow stirring with a rotation speed of 50-100r / min and a stirring time of 20-30min to promote the formation of flocs; the mixed liquid after the reaction is sent to the inclined tube sedimentation tank for a residence time of 1-2h, the supernatant is the treated water, and the bottom sludge is dehydrated by a plate and frame filter press and then transported for disposal; the ratio of the added mass of the treatment agent to the mass of fluoride ions in the wastewater is (1.2-2.0):1.

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