A defluorinating agent for acidic fluorine-containing wastewater and preparation method thereof

Abstract

The present invention relates to a defluorinating agent for acidic fluorine-containing wastewater and a preparation method thereof. The defluorinating agent comprises unsaturated carboxylic acid, hydrophobic unsaturated ester, stabilizer, polyacrylate monomer, olefin cationic monomer, modified tannic acid functional monomer, ammonium persulfate, sodium bisulfite, methacrylic acid glycidyl ether, acetic acid, aluminum sulfate and water. The preparation method uses unsaturated carboxylic acid, hydrophobic unsaturated ester and polyacrylate monomer to form a nano-microgel structure with carboxyl groups on the surface and pH response through emulsion polymerization. The graft polymerization of methacrylic acid glycidyl ether, olefin cationic monomer and modified tannic acid functional monomer and the introduction of aluminum sulfate further improve the structural stability and fluoride ion adsorption capacity of the defluorinating agent in acidic wastewater. The defluorinating agent has good fluidity in acidic fluorine-containing wastewater and can efficiently adsorb fluoride ions in the solution; in neutral or slightly alkaline conditions, it quickly swells and solidifies into a physical gel, thereby achieving the effect of coagulation and precipitation.

Description

Technical Field

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

[0002] As an important industrial reagent, fluoride is widely used in many industries such as metallurgy, chemical industry, pharmaceuticals, semiconductors, aerospace, etc. At the same time, with the mining and processing of fluorine-containing ores, a large amount of fluorine-containing wastewater is generated. Fluoride-containing wastewater has very high biological toxicity and ecological environmental damage ability. It will directly damage the soil and water quality when entering the environment, causing acute poisoning of animals, and even death in severe cases; at the same time, it will indirectly damage the local ecology, causing a large reduction in soil microorganisms and excessive fluoride content in crops. The treatment of fluoride ions in sewage directly determines the sustainable development of the ecological environment.

[0003] In order to meet the national fluorine-containing wastewater discharge standards and maintain ecological and environmental safety, fluorine-containing wastewater needs to be defluorinated before discharge. A lot of research has been done on wastewater defluorination processes at home and abroad. Commonly used defluorination methods include ion exchange, chemical precipitation, coagulation precipitation, Donnan dialysis, electrodialysis, membrane separation and adsorption.

[0004] Depending on the industry, raw materials, and production process, the composition of the fluoride-containing wastewater produced is also quite different. During the pickling process of steel products, steel plants will produce a large amount of pickling wastewater due to rinsing. The fluoride ion concentration is as high as 1200 mg / L, pH=1.5, and it also contains Ni 2+ , Mn 2+ The rare earth smelting industry produces a certain amount of acidic fluorine-containing wastewater during the production process, with a fluorine mass concentration of up to 2200mg / L~3200mg / L, and also contains other heavy metal ions such as Hg 2+ etc.; Phosphamide plants produce a certain amount of acidic fluorine-containing and phosphorus-containing wastewater during production, with the fluorine concentration below 1500 mg / L and the pH of the wastewater <1; the integrated circuit industry produces a certain amount of fluorine-containing wastewater in production, which is acidic, with a pH <2 and a fluorine concentration ≤1000 mg / L; electroplating (semiconductor) enterprises produce a certain amount of fluorine-containing wastewater in production, of which the pH of high-mass concentration fluorine-containing wastewater is 2.4-2.6, and the fluorine concentration is 2100 mg / L-2400 mg / L; the pH of low-mass concentration fluorine-containing wastewater is 5.3-5.5, and the fluorine concentration is 35 mg / L-45 mg / L, and it also contains Cu 2+ and Zn 2+ wait.

[0005] CN107285421A discloses a segmented treatment method for acidic fluorine-containing wastewater that is beneficial to sludge resource utilization, and achieves sludge reduction and sludge resource utilization through processes such as precipitation and adsorption. CN104591462A discloses a fluoride co-precipitation method for treating strongly acidic high-fluorine wastewater, firstly mixing and stirring the strongly acidic high-fluorine wastewater with aluminum hydroxide, and then adding sodium hydroxide aqueous solution and sodium chloride to neutralize according to the actual acidity of the high-fluorine wastewater, thereby reducing the amount of fluorine-containing sludge generated during the treatment process and improving the removal efficiency of fluoride ions. CN107792832A discloses a method for recovering fluorine resources in acidic fluorine-containing wastewater, and CN101823799A discloses a method for treating acidic fluorine-containing wastewater. The above-mentioned studies all focus on the treatment process of acidic fluorine-containing wastewater, and there is little research on the preparation method of defluorinating agent for acidic fluorine-containing wastewater. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings and defects mentioned in the above background technology, and provide a defluorination agent for acidic fluorine-containing wastewater and a preparation method thereof. The defluorination agent can be widely used in the treatment of various types of acidic industrial fluorine-containing wastewater, and can simultaneously achieve the adsorption and coagulation precipitation of fluoride ions. The defluorination operation is simple and the defluorination effect is good.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A defluoridating agent for acidic fluorine-containing wastewater comprises, by weight, 90-120 parts of unsaturated carboxylic acid, 60-78 parts of hydrophobic unsaturated ester, 2-10 parts of stabilizer, 1-6 parts of multiacrylate monomer, 38-50 parts of olefin cationic monomer, 62-80 parts of modified tannic acid functional monomer, 1-8 parts of ammonium persulfate, 1-5 parts of sodium bisulfite, 30-48 parts of glycidyl methacrylate, 10-24 parts of acetic acid, 5-12 parts of aluminum sulfate and 559-700 parts of water.

[0009] Furthermore, the unsaturated carboxylic acid includes one or more of acrylic acid, methacrylic acid, 3-methyl-2-butenoic acid, 2-acetamidoacrylic acid, trans-butenoic acid, fumaric acid, and maleic acid.

[0010] Furthermore, the hydrophobic unsaturated ester includes one or more of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, propyl acrylate, propyl methacrylate, methyl 3-hexenoate, and ethyl 3-hexenoate.

[0011] Furthermore, the stabilizer includes one or more of sodium dodecyl sulfonate, sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, Laponite clay, nano-SiO2, nano-aluminum silicate, and nano-magnesium silicate.

[0012] Furthermore, the multi-acrylate monomer includes one or more of trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, 1,4-butanediol diacrylate, ethylene glycol diacrylate, and polyethylene glycol diacrylate.

[0013] Furthermore, the olefin cationic monomer includes one or more of dimethyldiallylammonium chloride, allyltrimethylammonium chloride, allyl(3-aminopropyl)dimethylammonium chloride, (3-(methacrylamido)propyl)trimethylammonium chloride, and methacryloyloxyethyltrimethylammonium chloride.

[0014] Furthermore, the modified tannic acid functional monomer includes one or both of N-methylallylamine modified tannic acid functional monomer and diallylamine modified tannic acid functional monomer.

[0015] A method for preparing a defluorinating agent for acidic fluorine-containing wastewater comprises the following steps:

[0016] S1. Dissolve the stabilizer in water to prepare a solution with a mass fraction of 0.3%-1.8%;

[0017] S2. The unsaturated carboxylic acid, the hydrophobic unsaturated ester, the polyacrylate monomer, and the acetic acid are uniformly stirred to obtain a blend, and then 3%-6% of the blend is added to step S1 and stirred for 5-10 min, and the temperature is raised to 70-80 ° C and the reaction is continued with stirring for 15-30 min;

[0018] S3. Cooling to 50-60°C, sequentially adding ammonium persulfate and sodium bisulfite to the mixture of step S2, continuing the reaction at a constant temperature and stirring for 20-60 minutes, then adding the remaining blend dropwise, continuing the constant temperature reaction for 1-2 hours after the addition is complete, and cooling to room temperature to obtain a solution A, wherein ammonium persulfate is 1%-3% of the total mass of the unsaturated carboxylic acid, the hydrophobic unsaturated ester, and the multi-acrylate monomer;

[0019] S4. Add glycidyl methacrylate to solution A, raise the temperature to 60°C and stir to react for 24-72h. After the reaction, cool to room temperature to obtain solution B;

[0020] S5. dissolving the remaining ammonium persulfate in water to prepare a 5% solution by mass;

[0021] S6. Add solution B, olefin cationic monomer, and modified tannic acid functional monomer into the reaction kettle in sequence, stir and mix, and then heat to 60°C, then add the ammonium persulfate aqueous solution prepared in step S5 dropwise, continue the constant temperature reaction for 6-24 hours after the addition is complete, and cool to room temperature to obtain solution C.

[0022] S7. dissolving aluminum sulfate in water to prepare a solution having a mass fraction of 25%;

[0023] S8. Mix solution C and aluminum sulfate aqueous solution for reaction for 24-72 hours. After the reaction is completed, place the reaction mixture in a dialysis bag and dialyze for 3 days to obtain a defluorination agent for acidic fluoride-containing wastewater.

[0024] Mechanism of the present invention:

[0025] The invention firstly uses unsaturated carboxylic acid, hydrophobic unsaturated ester and multi-acrylate monomers to form a nanometer microgel with -COOH on the surface through emulsion polymerization; then methacrylate glycidyl ether and a part of carboxyl groups (-COOH) on the surface of the nanometer microgel are ring-opened under acidic conditions to form a microgel with both -COOH and olefin functional groups on the surface; then, olefin cationic monomers and modified tannic acid functional monomers are polymerized with olefins on the surface of the microgel under the action of an initiator to form a composite microgel with both covalent bonds and ionic bonds, and the remaining -COOH on the surface of the microgel can coordinate with aluminum ions, thereby fixing the aluminum ions in the microgel.

[0026] In acidic fluoride-containing wastewater, the prepared defluoridant has good dispersibility in aqueous solution and can form a homogeneous liquid with fluoride-containing wastewater in any proportion; but as the pH value increases to neutral or slightly alkaline, the composite microgel will quickly swell and solidify into a physical gel, thereby achieving the effect of coagulation and precipitation. The cationic monomer (-R3N + ), the polyphenol groups contained in tannic acid can combine with fluoride ions to form stable complexes; aluminum ions coordinated with -COOH on the surface of the defluoridating agent can form corresponding aluminum-fluoride complexes, such as sodium hexafluoroaluminate, which generally take away fluoride ions in the form of precipitation, while aluminum-fluoride complexes that cannot form precipitation can exist inside the microgel and be taken out together when the physical gel is formed.

[0027] Beneficial effects of the present invention:

[0028] (1) The defluoridating agent for acidic fluorine-containing wastewater prepared by the present invention has good fluidity in acidic fluorine-containing wastewater and can efficiently adsorb fluoride ions in the solution; in neutral or slightly alkaline conditions, it quickly swells and solidifies into a physical gel, thereby achieving a coagulation and precipitation effect.

[0029] (2) The defluorination agent for acidic fluorine-containing wastewater prepared by the present invention has the advantages of not affecting the acidity of the original solution and being easy to operate. After being directly added to the acidic fluorine-containing wastewater for reaction and adsorption, the pH is adjusted to neutral to form coagulation precipitation, thereby avoiding the cumbersome multiple feeding process.

[0030] (3) The present invention is used to prepare a defluoridating agent for acidic fluorine-containing wastewater, which can stabilize the fluoride ion concentration of the effluent water at below 5 mg / L. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following technical solution.

[0032] Example 1

[0033] This embodiment provides a defluorinating agent for acidic fluorine-containing wastewater, and the preparation method is as follows:

[0034] S1. Dissolve 2 g of sodium dodecyl sulfonate in 552.6 g of water to prepare a solution;

[0035] S2. 80 g of acrylic acid, 20 g of maleic acid, 78 g of methyl acrylate, 2 g of 1,4-butanediol diacrylate and 18 g of acetic acid were stirred to obtain a blend, and then 10 g of the blend was added to step S1 and stirred for 5 min, and the temperature was raised to 70 ° C and stirred for 15 min;

[0036] S3. Cool to 54 ° C, add 1.8 g of ammonium persulfate and 3.6 g of sodium bisulfite to the mixture of step S2, continue to stir and react at constant temperature for 40 min, then add the remaining blend dropwise, continue to react at constant temperature for 2 h after the addition is complete, and cool to room temperature to obtain solution A1;

[0037] S4. 30 g of glycidyl methacrylate was added to solution A1, the temperature was raised to 60 ° C and stirred for 48 h, and after the reaction was completed, the solution was cooled to room temperature to obtain solution B1;

[0038] S5. Dissolve 2.6 g of ammonium persulfate in 49.4 g of water to prepare a solution;

[0039] S6. Solution B1, 25 g of dimethyldiallyl ammonium chloride, 25 g of allyltrimethylammonium chloride, and 62 g of N-methylallylamine-modified tannic acid functional monomer were sequentially added into a reaction kettle, stirred and mixed, and then heated to 60° C., and then the ammonium persulfate aqueous solution prepared in step S5 was added dropwise. After the addition was completed, the reaction was continued at a constant temperature for 12 hours, and then cooled to room temperature to obtain solution C1.

[0040] S7. Dissolve 12 g of aluminum sulfate in 36 g of water;

[0041] S8. The solution C1 and the aluminum sulfate aqueous solution are mixed and reacted for 72 hours. After the reaction is completed, the reaction mixture is placed in a dialysis bag and dialyzed for 3 days to obtain a defluorination agent for acidic fluoride-containing wastewater.

[0042] Example 2

[0043] This embodiment provides a defluorinating agent for acidic fluorine-containing wastewater, and the preparation method is as follows:

[0044] S1. Dissolve 10 g of Laponite clay in 590° of water;

[0045] S2. 120 g of methacrylic acid, 25 g of propyl methacrylate, 35 g of cis-3-hexenoic acid methyl ester, 4 g of trimethylolpropane triacrylate, 2 g of ethoxylated trimethylolpropane triacrylate, and 10 g of acetic acid were stirred to obtain a blend, and then 11 g of the blend was added to step S1 and stirred for 10 min, and the temperature was raised to 80 ° C and stirred for 30 min;

[0046] S3. Cool to 60 ° C, sequentially add 3 g of ammonium persulfate and 5 g of sodium bisulfite to the mixture of step S2, continue to stir and react at constant temperature for 20 min, then add the remaining blend dropwise, continue to react at constant temperature for 1 h after the addition is complete, and cool to room temperature to obtain solution A2;

[0047] S4. 48 g of glycidyl methacrylate was added to solution A2, the temperature was raised to 60 ° C and stirred for 24 h, and the reaction was cooled to room temperature after the reaction to obtain solution B2;

[0048] S5. Dissolve 1 g of ammonium persulfate in 19 g of water to prepare a solution;

[0049] S6. Add solution B2, 38 g of methacryloyloxyethyl trimethylammonium chloride, and 70 g of diallylamine-modified tannic acid functional monomer into the reactor in sequence, stir and mix, and then heat to 60°C, then add the ammonium persulfate aqueous solution prepared in step S5 dropwise, continue the reaction at a constant temperature for 6 hours after the addition is complete, and cool to room temperature to obtain solution C2.

[0050] S7. Dissolve 5 g of aluminum sulfate in 15 g of water to prepare a solution;

[0051] S8. The solution C2 and the aluminum sulfate aqueous solution are mixed and reacted for 24 hours. After the reaction is completed, the reaction mixture is placed in a dialysis bag and dialyzed for 3 days to obtain a defluorination agent for acidic fluoride-containing wastewater.

[0052] Example 3

[0053] This embodiment provides a defluorinating agent for acidic fluorine-containing wastewater, and the preparation method is as follows:

[0054] S1. Dissolve 2g of nano-SiO2 and 4g of nano-aluminum silicate in 549.5g of water to form a solution;

[0055] S2. 60 g of 3-methyl-2-butenoic acid, 30 g of 2-acetamidoacrylic acid, 20 g of methyl methacrylate, 20 g of butyl acrylate, 20 g of butyl methacrylate, 1 g of ethylene glycol diacrylate, and 24 g of acetic acid were stirred to obtain a blend, and then 7 g of the blend was added to step S1 and stirred for 10 min, and the temperature was raised to 75 ° C and stirred for 15 min;

[0056] S3. Cool to 50 ° C, sequentially add 4.5 g of ammonium persulfate and 1 g of sodium bisulfite to the mixture of step S2, continue to react at constant temperature and stirring for 60 min, then add the remaining blend dropwise, continue to react at constant temperature for 1.5 h after the addition is complete, and cool to room temperature to obtain solution A3;

[0057] S4. 40 g of glycidyl methacrylate was added to solution A3, the temperature was raised to 60 ° C and the reaction was stirred for 72 h. After the reaction was completed, the solution was cooled to room temperature to obtain solution B3;

[0058] S5. Dissolve 3.5 g of ammonium persulfate in 66.5 g of water to prepare a 5% solution;

[0059] S6. Solution B3, 42 g of allyl (3-aminopropyl) dimethyl ammonium chloride, 40 g of N-methylallylamine-modified tannic acid functional monomer, and 40 g of diallylamine-modified tannic acid functional monomer were sequentially added into a reactor, stirred and mixed, and then heated to 60° C., and then the ammonium persulfate aqueous solution prepared in step S5 was added dropwise. After the addition was completed, the reaction was continued at a constant temperature for 24 hours, and then cooled to room temperature to obtain solution C3.

[0060] S7. Dissolve 8 g of aluminum sulfate in 24 g of water to prepare a solution with a mass fraction of 25%;

[0061] S8. The solution C3 and the aluminum sulfate aqueous solution are mixed and reacted for 60 hours. After the reaction is completed, the reaction mixture is placed in a dialysis bag and dialyzed for 3 days to obtain a defluorination agent for acidic fluoride-containing wastewater.

[0062] Example 4

[0063] This embodiment provides a defluorinating agent for acidic fluorine-containing wastewater, and the preparation method is as follows:

[0064] S1. Dissolve 2g of fatty alcohol polyoxyethylene ether and 2g of alkylphenol polyoxyethylene ether in 589g of water to prepare a solution;

[0065] S2. 120 g of acrylic acid, 78 g of methyl methacrylate, 6 g of polyethylene glycol diacrylate and 10 g of acetic acid were stirred to obtain a blend, and then 12 g of the blend was added to step S1 and stirred for 8 min, and the temperature was raised to 70 ° C and the reaction was stirred for 20 min;

[0066] S3. Cool to 60 ° C, sequentially add 2 g of ammonium persulfate and 3 g of sodium bisulfite to the mixture of step S2, continue to stir and react at constant temperature for 60 min, then add the remaining blend dropwise, continue to react at constant temperature for 1 h after the addition is complete, and cool to room temperature to obtain solution A4;

[0067] S4. 30 g of glycidyl methacrylate was added to solution A4, the temperature was raised to 60 ° C and the reaction was stirred for 72 h. After the reaction was completed, the solution was cooled to room temperature to obtain solution B4;

[0068] S5. Dissolve 0.5 g of ammonium persulfate in 9.5 g of water to prepare a 5% solution;

[0069] S6. Solution B4, 46 g (3-(methacrylamido)propyl)trimethylammonium chloride, and 62 g N-methylallylamine-modified tannic acid functional monomer were sequentially added into a reaction kettle, stirred and mixed, and then heated to 60° C., and then the ammonium persulfate aqueous solution prepared in step S5 was added dropwise. After the addition was completed, the reaction was continued at a constant temperature for 8 hours, and then cooled to room temperature to obtain solution C4.

[0070] S7. Dissolve 10 g of aluminum sulfate in 30 g of water to prepare a solution with a mass fraction of 25%;

[0071] S8. The solution C4 and the aluminum sulfate aqueous solution are mixed and reacted for 48 hours. After the reaction is completed, the reaction mixture is placed in a dialysis bag and dialyzed for 3 days to obtain a defluorination agent for acidic fluoride-containing wastewater.

[0072] Comparative Example 1

[0073] This comparative example provides a defluorinating agent for acidic fluorine-containing wastewater, and the preparation method is as follows:

[0074] S1. Dissolve 2 g of sodium dodecyl sulfonate in 552.6 g of water to prepare a solution;

[0075] S2. 80 g of acrylic acid, 20 g of maleic acid, 78 g of methyl acrylate and 18 g of acetic acid were stirred to obtain a blend, and then 10 g of the blend was added to step S1 and stirred for 5 min, and the temperature was raised to 70 ° C and stirred for 15 min;

[0076] S3. Cool to 54 ° C, sequentially add 1.8 g of ammonium persulfate and 3.6 g of sodium bisulfite to the mixture of step S2, continue to react at constant temperature and stirring for 40 min, then add the remaining blend dropwise, continue to react at constant temperature for 2 h after the addition is complete, and cool to room temperature to obtain solution A5;

[0077] S4. 30 g of glycidyl methacrylate was added to solution A1, the temperature was raised to 60 ° C and stirred for 48 h, and the reaction was cooled to room temperature to obtain solution B5;

[0078] S5. Dissolve 2.6 g of ammonium persulfate in 49.4 g of water to prepare a solution;

[0079] S6. Solution B5, 25 g of dimethyldiallyl ammonium chloride, 25 g of allyltrimethylammonium chloride, and 62 g of N-methylallylamine-modified tannic acid functional monomer were sequentially added into a reactor, stirred and mixed, and then heated to 60°C, and then the ammonium persulfate aqueous solution prepared in step S5 was added dropwise. After the addition was completed, the reaction was continued at a constant temperature for 12 hours, and then cooled to room temperature to obtain solution C5.

[0080] S7. Dissolve 12 g of aluminum sulfate in 36 g of water;

[0081] S8. The solution C5 and the aluminum sulfate aqueous solution are mixed and reacted for 72 hours. After the reaction is completed, the reaction mixture is placed in a dialysis bag and dialyzed for 3 days to obtain a defluorination agent for acidic fluoride-containing wastewater.

[0082] Comparative Example 2

[0083] This comparative example provides a defluorinating agent for acidic fluorine-containing wastewater, and the preparation method is as follows:

[0084] S1. Dissolve 2 g of sodium dodecyl sulfonate in 552.6 g of water to prepare a solution;

[0085] S2. 80 g of acrylic acid, 20 g of maleic acid, 78 g of methyl acrylate, 2 g of 1,4-butanediol diacrylate and 18 g of acetic acid were stirred to obtain a blend, and then 10 g of the blend was added to step S1 and stirred for 5 min, and the temperature was raised to 70 ° C and stirred for 15 min;

[0086] S3. Cool to 54°C, add 1.8 g of ammonium persulfate and 3.6 g of sodium bisulfite to the mixture of step S2, continue to stir and react at constant temperature for 40 min, then add the remaining blend dropwise, continue to react at constant temperature for 2 h after the addition is complete, and cool to room temperature to obtain solution A1.

[0087] Comparative Example 3

[0088] S1. Dissolve 2 g of sodium dodecyl sulfonate in 552.6 g of water to prepare a solution;

[0089] S2. 80 g of acrylic acid, 20 g of maleic acid, 78 g of methyl acrylate, 2 g of 1,4-butanediol diacrylate, 18 g of acetic acid, 25 g of dimethyldiallyl ammonium chloride, 25 g of allyltrimethylammonium chloride, and 62 g of N-methylallylamine-modified tannic acid functional monomer were stirred to obtain a blend, and then 10 g of the blend was added to step S1 and stirred for 5 min, and the temperature was raised to 70 ° C and stirred for 15 min;

[0090] S3. Cool to 54 ° C, add 1.8 g of ammonium persulfate and 3.6 g of sodium bisulfite to the mixture of step S2, continue to stir and react at constant temperature for 40 min, then add the remaining blend dropwise, continue to react at constant temperature for 2 h after the addition is complete, and cool to room temperature to obtain solution A6;

[0091] S4. Dissolve 12 g of aluminum sulfate in 36 g of water;

[0092] S5. The solution A6 and the aluminum sulfate aqueous solution were mixed and reacted for 72 hours. After the reaction was completed, the reaction mixture was placed in a dialysis bag and dialyzed for 3 days to obtain a defluorination agent for acidic fluoride-containing wastewater.

[0093] The acidic fluorine-containing wastewater prepared in Examples 1-4 and Comparative Examples 1-3 was used to treat pickling wastewater discharged from the cold rolling section of a steel plant. The pH of the fluorine-containing wastewater to be treated was 1-2, and the fluorine ion concentration was 100 mg / L. Fluorine-containing wastewater was taken from a semiconductor factory, and the pH of the fluorine-containing wastewater was 5-6, and the fluorine ion concentration was 20 mg / L. After the fluorine-containing wastewater reacted with the defluoridation agent, the pH was adjusted to above 7.04 and allowed to settle. The supernatant was taken and the fluorine ion concentration was detected by a spectrophotometer. The detection method of the fluorine ion concentration was referred to "Determination of Fluoride in Water Quality - Fluorine Reagent Spectrophotometry" (HJ488-2009).

[0094] Table 1 The use of defluorinating agents in fluorine-containing wastewater in the cold rolling section of a steel plant

[0095]

[0096] Table 2 The use of defluoridation agents in fluorine-containing wastewater from a semiconductor factory

[0097]

[0098] Through the above experimental comparison, it was found that Examples 1 to 4 have good defluorination effects on strong acid high-concentration fluorine-containing wastewater (fluorine-containing wastewater from the cold rolling section of a steel plant) and weak acid low-concentration fluorine-containing wastewater (fluorine-containing wastewater from a semiconductor factory).

[0099] Comparative Example 1 Compared with Example 1, no multi-acrylate monomer (2 g 1,4-butanediol diacrylate) was added, resulting in the failure to form a microgel structure, and thus no physical gel could be formed in a neutral or alkaline environment. The very small amount of sedimentation may be caused by Al 3+ Formed by adsorption and sedimentation.

[0100] Compared with Example 1, Comparative Example 2 used only Solution A1, i.e., only contained microgels with carboxyl groups on the surface. Although it had pH-responsive gelation, the defluorination effect was poor. The defluorination rate of Comparative Example 2 in Table 1 reached 67.94%, which may be because when the fluoride ion concentration was high, the fluoride ions partially entered the microgel and took away some of the fluoride ions with the sedimentation; while the defluorination rate of Comparative Example 2 in Table 2 was only 27.35%, which may be because the fluoride ion concentration was low, and the probability of the fluoride ions partially entering the microgel became lower.

[0101] Compared with Example 1, Comparative Example 3 directly polymerizes unsaturated carboxylic acid, hydrophobic unsaturated ester, multi-acrylate monomer, olefin cationic monomer, and modified tannic acid functional monomer in a one-step reaction. Since tannic acid contains more phenolic hydroxyl groups, it is very easy to entangle with unreacted unsaturated carboxylic acid, hydrophobic unsaturated ester, and multi-acrylate monomer through hydrogen bonds, thereby forming multiple crosslinks and directly forming a gel.

Claims

1. A defluorinating agent for acidic fluorine-containing wastewater, characterized in that: The invention comprises, by weight: 90-120 parts of unsaturated carboxylic acid, 60-78 parts of hydrophobic unsaturated ester, 2-10 parts of stabilizer, 1-6 parts of multi-acrylate monomer, 38-50 parts of olefin cationic monomer, 62-80 parts of modified tannic acid functional monomer, 1-8 parts of ammonium persulfate, 1-5 parts of sodium bisulfite, 30-48 parts of glycidyl methacrylate, 10-24 parts of acetic acid, 5-12 parts of aluminum sulfate and 559-700 parts of water.

2. The defluorinating agent for acidic fluorine-containing wastewater according to claim 1, characterized in that: The unsaturated carboxylic acid includes one or more of acrylic acid, methacrylic acid, 3-methyl-2-butenoic acid, 2-acetamidoacrylic acid, trans-butenoic acid, fumaric acid, and maleic acid.

3. The defluorinating agent for acidic fluorine-containing wastewater according to claim 1, characterized in that: The hydrophobic unsaturated ester includes one or more of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, propyl acrylate, propyl methacrylate, methyl 3-hexenoate, and ethyl 3-hexenoate.

4. The defluorinating agent for acidic fluorine-containing wastewater according to claim 1, characterized in that: The stabilizer includes one or more of sodium dodecyl sulfonate, sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, Laponite clay, nano SiO2, nano aluminum silicate, and nano magnesium silicate.

5. The defluorinating agent for acidic fluorine-containing wastewater according to claim 1, characterized in that: The multi-acrylate monomer includes one or more of trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, 1,4-butanediol diacrylate, ethylene glycol diacrylate, and polyethylene glycol diacrylate.

6. The defluorinating agent for acidic fluorine-containing wastewater according to claim 1, characterized in that: The olefin cationic monomer includes one or more of dimethyldiallylammonium chloride, allyltrimethylammonium chloride, allyl(3-aminopropyl)dimethylammonium chloride, (3-(methacryloylamino)propyl)trimethylammonium chloride, and methacryloyloxyethyltrimethylammonium chloride.

7. The defluorinating agent for acidic fluorine-containing wastewater according to claim 1, characterized in that: The modified tannic acid functional monomers include one or both of N-methylallylamine modified tannic acid functional monomers and diallylamine modified tannic acid functional monomers.

8. A method for preparing a defluorinating agent for acidic fluorine-containing wastewater, characterized in that: The following steps are involved: S1. Dissolve the stabilizer in water to prepare a solution with a mass fraction of 0.3%-1.8%; S2. The unsaturated carboxylic acid, the hydrophobic unsaturated ester, the polyacrylate monomer, and the acetic acid are uniformly stirred to obtain a blend, and then 3%-6% of the blend is added to step S1 and stirred for 5-10 min, and the temperature is raised to 70-80 ° C and the reaction is continued with stirring for 15-30 min; S3. Cooling to 50-60°C, sequentially adding ammonium persulfate and sodium bisulfite to the mixture of step S2, continuing the reaction at a constant temperature and stirring for 20-60 minutes, then adding the remaining blend dropwise, continuing the constant temperature reaction for 1-2 hours after the addition is complete, and cooling to room temperature to obtain a solution A, wherein ammonium persulfate is 1%-3% of the total mass of the unsaturated carboxylic acid, the hydrophobic unsaturated ester, and the multi-acrylate monomer; S4. Add glycidyl methacrylate to solution A, raise the temperature to 60°C and stir to react for 24-72h. After the reaction, cool to room temperature to obtain solution B; S5. dissolving the remaining ammonium persulfate in water to prepare a 5% solution by mass; S6. Solution B, olefin cationic monomer, and modified tannic acid functional monomer are sequentially added to a reaction vessel, stirred and mixed, and then heated to 60° C., and then the ammonium persulfate aqueous solution prepared in step S5 is added dropwise. After the addition is completed, the reaction is continued at a constant temperature for 6-24 hours, and cooled to room temperature to obtain a solution C; S7. dissolving aluminum sulfate in water to prepare a solution having a mass fraction of 25%; S8. Mix solution C and aluminum sulfate aqueous solution for reaction for 24-72 hours. After the reaction is completed, place the reaction mixture in a dialysis bag and dialyze for 3 days to obtain a defluorination agent for acidic fluoride-containing wastewater.

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