Fluorine removal agent as well as preparation method and application thereof

Abstract

The invention discloses a fluorine removal agent as well as a preparation method and application thereof, and relates to the technical field of fluorine ion treatment. The fluorine removal agent comprises the following preparation raw materials: metal salt containing aluminum and iron, an acrylamide monomer and a cationic polymer monomer. The fluorine removal agent can achieve deep fluorine removal of industrial fluorine-containing wastewater, flocs generated in the fluorine removal process are large, compact and high in settling speed, and the fluorine removal agent has the advantages of being wide in pH use range, high in removal efficiency and the like, can rapidly reduce the concentration of fluorine ions in the wastewater to 1.0 mg / L or below, still has the fluorine removal rate of 80% or above for fluorine-containing wastewater with the concentration lower than 10 mg / L, and has a good application prospect. And the dosage of the fluorine removal agent is low, and an excellent fluorine removal effect can be realized when the dosage is less than 500mg / L.

Description

Technical Field

[0001] The invention relates to the technical field of fluoride ion treatment, and in particular to a defluorination agent and a preparation method and application thereof. Background Art

[0002] Fluorine is one of the elements widely distributed in nature, especially in water bodies in nature. Excessive intake of fluorine can lead to fluorine poisoning. Fluorine poisoning has become one of the problems affecting human health. The fluorine content of domestic water should be controlled between 0.5 and 1 mg / L, so it is necessary to strictly control the fluorine content in discharged water.

[0003] The main methods currently used to treat fluoride ions in wastewater include precipitation, adsorption, electrocoagulation, electrodialysis, reverse osmosis and ion exchange. When treating high-fluoride wastewater, the calcium salt precipitation method is widely used because of its simple process, easy operation and low cost. However, this method is not very effective when treating low-fluoride wastewater.

[0004] Commonly used methods for deep defluorination of low-fluoride concentration wastewater include adsorption and coagulation sedimentation. However, the adsorption materials used in the adsorption method often have disadvantages such as low adsorption capacity, high price and complex process operation, such as activated alumina adsorbent and bone char adsorbent, which limits its application in deep defluorination of large-scale industrial wastewater. The defluorination agents used in the coagulation sedimentation method mainly include inorganic salt coagulants, such as aluminum sulfate, polyferric sulfate, aluminum chloride, polyaluminum chloride and polyaluminum ferric chloride. These single coagulants have problems such as large dosage of reagents, poor wastewater treatment effect, small flocs after flocculation, and long sedimentation time during deep defluorination. In addition, excessive addition of inorganic salt coagulants will lead to residual metal ions in the flocculation effluent and sludge, increasing the load of subsequent treatment processes.

[0005] In order to overcome the problems of limited defluorination effect, small floccules after treatment, slow sedimentation rate, large amount of defluorination agent, high cost of wastewater treatment, etc. of single aluminum salt or iron salt as defluorination agent, the prior art discloses a method for preparing a deep defluorination agent, the raw materials of which include aluminum sulfate, iron sulfate, sodium silicate and deionized water, which are obtained after hydrolysis polymerization, alkalinity adjustment, coagulation and aging. The defluorination agent in this scheme uses aluminum salt and iron salt as metal salt components, polydimethyldiallylammonium chloride as organic component, and combines inorganic and organic components by covalent bonds. At the same time, the addition of silicon element effectively improves the formation of high-polymer aluminum and high-polymer iron. The obtained defluorination agent is a high molecular polymer, which plays a synergistic role of inorganic and organic flocculants, and improves the defluorination effect compared with traditional defluorination agents. However, the pH application range of this deep defluorination agent is relatively narrow, and the wastewater pH needs to be adjusted to alkaline to achieve a good defluorination effect. It also cannot solve the problem of large dosage and high cost of defluorination agent. For wastewater with a fluorine content of 20 mg / L, the dosage of defluorination agent reaches 1500 mg / L or more to achieve a defluorination rate of more than 80%. The defluorination effect for low-fluorine wastewater with a fluorine content of less than 10 mg / L needs to be improved. At the same time, the preparation process of this deep defluorination agent is complicated, the aging reaction time is long, and the preparation cost is also high. Summary of the invention

[0006] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, the object of the present invention is to provide a defluorinating agent obtained by polymerization of aluminum salt, iron salt, acrylamide monomer and cationic polymer monomer, which can effectively remove fluorine from low-concentration fluorine-containing wastewater at a low dosage.

[0007] The second aspect of the present invention is to provide a method for preparing a defluorinating agent.

[0008] The third aspect of the present invention is to provide an application of a defluorination agent.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] The first aspect of the present invention provides a defluorination agent, comprising the following preparation raw materials: a metal salt containing aluminum and iron, an acrylamide monomer and a cationic polymer monomer.

[0011] In view of the limitations and challenges of current fluoride ion treatment technology, the present invention provides a defluoridation agent, which is an inorganic-organic polymer obtained by copolymerization of components including aluminum and iron metal salts, acrylamide monomers, and cationic monomers. When removing fluoride ions from wastewater, the defluoridation agent has both the net-catching and sweeping functions of inorganic flocculants and the adsorption and bridging functions of organic polymer flocculants. Therefore, the flocs generated in the defluorination process are large and compact, and the sedimentation rate is fast. In addition, the defluoridation agent has the advantages of a wide pH range of use and high removal efficiency. It can quickly reduce the fluoride ion concentration in wastewater to below 1.0 mg / L, and still has a strong removal ability for fluoride ions in low-concentration fluoride-containing wastewater, thereby improving the efficiency and quality of fluoride ion treatment in water, which is beneficial to ensuring the sustainable development of human health and the environment.

[0012] In some embodiments of the present invention, the weight average molecular weight of the defluorination agent is 350,000 to 1,000,000.

[0013] In some preferred embodiments of the present invention, the weight average molecular weight of the defluorination agent is 400,000 to 900,000.

[0014] In some specific embodiments of the present invention, the weight average molecular weight of the defluorination agent is 600,000 to 900,000.

[0015] Specifically, the weight average molecular weight of the defluorination agent of the present invention can be 350,000, 400,000, 450,000, 550,000, 650,000, 750,000, 850,000, 950,000 or 1,000,000.

[0016] In some embodiments of the present invention, the mass ratio of the acrylamide monomer to the cationic polymer monomer is 1:(1-4).

[0017] In some preferred embodiments of the present invention, the mass ratio of the acrylamide monomer to the cationic polymer monomer is 1:(1-3.5).

[0018] In some specific embodiments of the present invention, the mass ratio of the acrylamide monomer to the cationic polymer monomer is 1:(1-2).

[0019] Specifically, in the present invention, the mass ratio of acrylamide monomer to the cationic polymer monomer is 1:1.25, 1:2, 1:3 or 1:3.5.

[0020] The defluorinating agent of the present invention can ensure that the defluorinating agent has sufficient cationicity by controlling the mass ratio of acrylamide monomer to cationic polymer monomer in the polymerization reaction, thereby further optimizing the treatment effect of the defluorinating agent on low-concentration fluoride ions.

[0021] In some embodiments of the present invention, the cationic degree of the defluoridating agent is 30-60%.

[0022] In some preferred embodiments of the present invention, the cationic degree of the defluorinating agent is 30-55%.

[0023] In some embodiments of the present invention, the mass fraction of aluminum oxide in the defluorination agent is 8 to 11%.

[0024] In some preferred embodiments of the present invention, the mass fraction of aluminum oxide in the defluorination agent is 9-11%.

[0025] In some embodiments of the present invention, the raw material components of the defluorination agent also include an oxidant and a reducing agent.

[0026] The oxidant and the reductant of the present invention form a redox initiator or a redox initiation system. The redox initiation system includes two parts with oxidizing and reducing properties, and generates free radicals through redox reaction, thereby initiating monomer polymerization (the present invention initiates polymerization of acrylamide and cationic monomers).

[0027] In some embodiments of the present invention, the amount of the reducing agent added is 0.15-2% of the total mass of the acrylamide monomer and the cationic polymer monomer.

[0028] In some preferred embodiments of the present invention, the amount of the reducing agent added is 0.15-1.5% of the total mass of the acrylamide monomer and the cationic polymer monomer.

[0029] In some specific embodiments of the present invention, the amount of the reducing agent added is 0.5-1% of the total mass of the acrylamide monomer and the cationic polymer monomer.

[0030] Specifically, the amount of the reducing agent added in the present invention can be 0.15%, 0.3%, 0.5%, 0.6%, 0.8%, 1%, 1.5% or 2% of the total mass of the acrylamide monomer and the cationic polymer monomer.

[0031] In some embodiments of the present invention, the added amount of the oxidant is 0.01 to 1% of the total mass of the acrylamide monomer and the cationic polymerization monomer.

[0032] In some preferred embodiments of the present invention, the added amount of the oxidant is 0.3-0.6% of the total mass of the acrylamide monomer and the cationic polymerization monomer.

[0033] In some embodiments of the present invention, the cationic polymer monomer includes at least one of dimethyldiallylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, and acryloyloxyethyltrimethylammonium chloride.

[0034] In some embodiments of the present invention, the metal salt containing aluminum and iron includes a composite aluminum-iron salt, such as aluminum-iron sulfate and aluminum-iron chloride.

[0035] In some preferred embodiments of the present invention, the aluminum salt and iron salt include aluminum ferric sulfate.

[0036] In some embodiments of the present invention, the reducing agent includes at least one of sodium sulfite, sodium bisulfite, sodium pyrosulfite, and ammonium ferrous sulfate.

[0037] In some embodiments of the present invention, the oxidant includes at least one of ammonium persulfate, potassium persulfate, sodium persulfate, and tert-butyl hydroperoxide.

[0038] The second aspect of the present invention provides a method for preparing the defluorination agent according to the first aspect of the present invention, comprising the following steps:

[0039] Acrylamide monomer and cationic polymer monomer are added to aluminum ferric sulfate solution to mix and dissolve, an oxidant is added, and then a reducing agent is added dropwise to carry out polymerization reaction to obtain the defluorination agent.

[0040] The defluorination agent of the present invention has a simple preparation process, which solves the problem of complicated production process of existing defluorination agent products. The obtained defluorination agent solves the problems of narrow pH application range, large dosage of agent, low defluorination efficiency and the like of traditional defluorination agents.

[0041] In some embodiments of the present invention, the heating rate during the polymerization reaction is 0.3-0.6° C. / min.

[0042] If the heating rate is too fast, gelation is likely to occur, and the defluorination effect of the obtained product will be poor.

[0043] In some embodiments of the present invention, the polymerization reaction temperature is 60-80°C.

[0044] In some preferred embodiments of the present invention, the polymerization reaction temperature is 65-75°C.

[0045] In the present invention, the temperature of the polymerization reaction is increased to 60-80° C. at the above-mentioned heating rate and maintained until the reaction is completed.

[0046] In some embodiments of the present invention, the polymerization reaction time is 1 to 3 hours.

[0047] In some preferred embodiments of the present invention, the polymerization reaction time is 1.5 to 2.5 hours.

[0048] In some embodiments of the present invention, the dropping speed of the reducing agent is 0.5 to 1.5 mL / min.

[0049] In some preferred embodiments of the present invention, the dropping speed of the reducing agent is 0.5 to 0.8 mL / min.

[0050] In some specific embodiments of the present invention, the dropping speed of the reducing agent is 0.55 to 0.75 mL / min.

[0051] The dripping speed of the reducing agent and its addition amount cooperate with each other, affecting the smooth progress of the reaction and the smooth synthesis of the defluorinating agent.

[0052] In some embodiments of the present invention, the aluminum ferric sulfate is obtained by reacting gibbsite and sulfuric acid.

[0053] In some preferred embodiments of the present invention, the aluminum oxide content of the gibbsite is 58-66%; and the particle size of the ore powder is 100-300 meshes.

[0054] In some preferred embodiments of the present invention, the gibbsite is mixed with water and then sulfuric acid is added; the mass ratio of water to gibbsite is 1:(0.65-0.85).

[0055] In some embodiments of the present invention, the reaction temperature of gibbsite and sulfuric acid is 100-110°C.

[0056] In some preferred embodiments of the present invention, the reaction temperature of gibbsite and sulfuric acid is 100-105°C.

[0057] Controlling the above reaction temperature is beneficial to ensuring the dissolution of aluminum and iron in gibbsite.

[0058] In some embodiments of the present invention, the mass ratio of sulfuric acid to gibbsite is 1:(0.5-0.8).

[0059] In some preferred embodiments of the present invention, the mass ratio of sulfuric acid to gibbsite is 1:(0.52-0.72).

[0060] In some embodiments of the present invention, the mass ratio of the acrylamide monomer to gibbsite is 1:(5-11).

[0061] Specifically, the added mass ratio of acrylamide monomer to gibbsite may be 1:5, 1:7, 1:10.5, or 1:11.

[0062] In some embodiments of the present invention, the mass ratio of the cationic polymerization monomer to gibbsite powder is 1:(1-4).

[0063] In some preferred embodiments of the present invention, the mass ratio of the cationic polymerization monomer to gibbsite powder is 1:(2-4).

[0064] In some preferred embodiments of the present invention, the mass ratio of the cationic polymerization monomer to gibbsite powder is 1:(3-4).

[0065] The third aspect of the present invention provides an application of the defluorinating agent described in the first aspect of the present invention or the defluorinating agent obtained by the preparation method described in the second aspect of the present invention in the field of water treatment.

[0066] The defluoridation agent of the present invention can effectively remove fluoride ions in wastewater, is suitable for industrial wastewater treatment, the fluoride ion concentration of the treated wastewater is lower than 1 mg / L, and can achieve deep defluoridation of low-concentration fluoride-containing wastewater.

[0067] In some embodiments of the present invention, the water comprises fluoride-containing wastewater.

[0068] In some embodiments of the present invention, the fluoride ion concentration in the water is 1 to 10 mg / L.

[0069] In some preferred embodiments of the present invention, the fluoride ion concentration in the water is 3-6 mg / L.

[0070] In some embodiments of the present invention, the amount of the defluoridating agent used in the water treatment is 200-500 mg / L.

[0071] Specifically, the dosage of the defluoridating agent can be 200 mg / L, 250 mg / L, 300 mg / L, 350 mg / L, 400 mg / L, 450 mg / L, or 500 mg / L.

[0072] In some preferred embodiments of the present invention, the pH of the fluorine-containing wastewater is 5-10.

[0073] In some specific embodiments of the present invention, the pH of the fluorine-containing wastewater is 6-9.

[0074] In some embodiments of the present invention, the water treatment time is 30 to 60 minutes.

[0075] Compared with the prior art, the present invention has the following beneficial effects:

[0076] (1) The defluorinating agent of the present invention can achieve deep defluorination of industrial fluorine-containing wastewater. The defluorinating agent is an inorganic-organic polymer prepared by copolymerization of metal salts containing aluminum and iron, acrylamide monomers, and cationic monomers. When removing fluoride ions from wastewater, the defluorinating agent has both the net-catching and sweeping functions of an inorganic flocculant and the adsorption and bridging functions of an organic polymer flocculant, so that the flocs generated during the defluorination process are large and compact, with a fast sedimentation rate, and have the advantages of a wide pH range of use and high removal efficiency. The defluorinating agent can quickly reduce the fluoride ion concentration in the wastewater to below 1.0 mg / L, and still has a strong removal ability for fluoride ions in low-concentration fluoride-containing wastewater.

[0077] (2) The preparation method of the defluorination agent of the present invention is simple and easy to operate, and the reaction aging time is short, the process cost is low, and mass production can be achieved.

[0078] (3) The defluoridation agent of the present invention can efficiently remove fluoride ions in low-concentration fluoride-containing wastewater, and still has a fluoride removal rate of more than 80% for fluoride-containing wastewater with a concentration below 10 mg / L. In addition, the dosage of the defluoridation agent is low, and an excellent defluoridation effect can be achieved at a dosage below 500 mg / L. The fluoride ion concentration of the treated wastewater is less than 1 mg / L. The present invention is suitable for the field of water treatment, especially for treating fluoride-containing wastewater. DETAILED DESCRIPTION

[0079] The present invention is further described in detail below by specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial sources or can be obtained by prior art methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0080] Example 1

[0081] (1) Add 105g of tap water and 80g of gibbsite powder (alumina content of 55%, mesh size of 200) into a bottle-bottom flask, slowly add 60ml of 98% industrial sulfuric acid while stirring evenly, and then start heating. The reaction time is 1.5h, and the process temperature is controlled at 100-105°C to ensure that the reflux liquid continues to drip. After the reaction is completed, add cooled tap water and stir evenly, and then filter while hot to obtain aluminum ferric sulfate solution;

[0082] (2) In the aluminum ferric sulfate solution prepared in step (1), 10 g of acrylamide monomer and 35 g of dimethyldiallyl ammonium chloride cationic monomer are added in sequence. After the above raw materials are evenly dissolved by magnetic stirring, 2.25 mL of 10% ammonium persulfate solution is added at one time, and then 11.25 mL of 2% sodium sulfite solution is slowly added dropwise at a sodium sulfite addition rate of 0.8 mL / min. The system temperature is maintained at a rate of 0.3-0.6°C / min, and the temperature is raised to 70°C. The polymerization reaction is carried out for 2.5 hours to finally obtain a brown defluorination agent solution. The molecular weight is 450,000, the Al2O3 mass fraction is 9.5%, and the cationic degree is 54%.

[0083] Example 2

[0084] (1) Add 105g of tap water and 80g of gibbsite powder into a flask, slowly add 60mL of 98% industrial sulfuric acid while stirring evenly, and then start heating. The reaction time is 1.5h. The process temperature is controlled at 100-105°C to ensure that the reflux liquid continues to drip. After the reaction is completed, add cooled tap water and stir evenly, then filter while hot to obtain an aluminum ferric sulfate solution;

[0085] (2) In the aluminum ferric sulfate solution prepared in step (1), 15 g of acrylamide monomer and 30 g of dimethyldiallyl ammonium chloride cationic monomer are added in sequence. After the above raw materials are evenly dissolved by magnetic stirring, 2.07 mL of 10% ammonium persulfate solution is added at one time, and then 11.25 mL of 2% sodium metabisulfite solution is slowly added dropwise. The reducing agent is added at a rate of 0.72 mL / min. The system temperature is maintained at a rate of 0.3-0.6°C / min. The temperature is raised to 70°C and the polymerization reaction is carried out for 2.5 hours to obtain a brown defluorination agent solution. The molecular weight is 670,000, the Al2O3 mass fraction is 9.8%, and the cationic degree is 45%.

[0086] Example 3

[0087] (1) Add 100g of tap water and 80g of gibbsite powder into a flask, slowly add 60mL of 98% industrial sulfuric acid while stirring evenly, and then start heating. The reaction time is 1.5h. The process temperature is controlled at 100-105°C to ensure that the reflux liquid continues to drip. After the reaction is completed, add cooled tap water and stir evenly, then filter while hot to obtain an aluminum ferric sulfate solution;

[0088] (2) In the aluminum ferric sulfate solution prepared in step (1), 20 g of acrylamide monomer and 25 g of dimethyldiallyl ammonium chloride cationic monomer are added in sequence. After the above raw materials are evenly dissolved by magnetic stirring, 2.54 mL of 10% mass concentration oxidant solution is added at one time, and then 11.30 mL of 2% mass concentration reducing agent solution is slowly added dropwise at a reducing agent dropping rate of 0.56 mL / min. The system temperature is maintained at a rate of 0.3-0.6°C / min, and the temperature is raised to 70°C. The polymerization reaction is carried out for 2.5 hours to finally obtain a brown defluorination agent solution. The molecular weight is 880,000, the Al2O3 mass fraction is 10.1%, and the cationic degree is 32%.

[0089] The detection method of cationicity in Examples 1 to 3 refers to GB / T 31246-2014 "Technical Conditions and Test Methods for Cationic Polyacrylamide as Water Treatment Agent".

[0090] Comparative Example 1

[0091] The commercially available Qingyuan brand defluorinating agent (CL-2) is a defluorinating agent product with an aluminum oxide content of 9.5 wt % purchased from Shenzhen Changlong Technology Co., Ltd.

[0092] Comparative Example 2

[0093] The commercially available WDCF-1 defluorinating agent is a high molecular polymer and was purchased from Guangdong Shanmei Environmental Technology Co., Ltd.

[0094] Comparative Example 3

[0095] The commercially available JC-WF8 defluorinating agent, which is a composite chemical flocculation defluorinating precipitant, was purchased from Shanghai Jiaci Environmental Technology Co., Ltd.

[0096] Comparative Example 4

[0097] Commercially available aluminum ferric sulfate and acrylamide-dimethyldiallylammonium chloride copolymer product are uniformly mixed in a mass ratio of 10:2 to obtain a defluorinating agent.

[0098] Test Example 1

[0099] 1. Take 500 mL of fluorine-containing wastewater from a semiconductor industry in Shenzhen, the pH value of which is 6.8. Under the condition of magnetic stirring, add 400 mg / L of the defluorinating agent of Examples 1 to 3 and Comparative Examples 1 to 4, respectively, and then react for 30 minutes at a stirring speed of 120 r / min, and finally let it stand for 30 minutes. The fluoride ion concentration is detected by a Leix PXSJ-226T ion meter. The treatment effect is shown in Table 1.

[0100] Table 1 Comparison of the defluorination effects of Examples 1 to 3 and Comparative Examples 1 to 4 on semiconductor fluoride-containing wastewater

[0101]

[0102] Test Example 2

[0103] 2. Take 500 mL of fluorine-containing wastewater from a coking industry in Shandong, adjust the pH of the wastewater to 8.5 with sodium hydroxide solution, add 250 mg / L of the defluorinating agents of Examples 1 to 3 and Comparative Examples 1 to 4 under magnetic stirring, then react for 30 minutes at a stirring speed of 120 r / min, and finally let it stand for 30 minutes. The fluoride ion concentration is detected by a Leix PXSJ-226T ion meter. The treatment effect is shown in Table 2.

[0104] Table 2 Comparison of the defluorination effects of Examples 1 to 3 and Comparative Examples 1 to 3 on coking fluorine-containing wastewater

[0105]

[0106] From the results of Table 1 and Table 2, it can be seen that after the defluorination agent of the present invention treats low-concentration fluoride-containing wastewater, the residual fluoride ion concentration of the wastewater is below 1 mg / L, which meets the limit specified in GB5749-2022 "Sanitary Standards for Drinking Water" and the Class III water quality standard specified in GB3838-2002 "Surface Water Environmental Quality Standards", and can effectively achieve deep defluorination at a lower defluorination agent dosage. In addition, by comparing the results of Test Example 1 and Test Example 2, it can be seen that in wastewater with different pH values, the defluorination agent of the present invention can show excellent defluorination performance, has a wide pH application range, and is suitable for defluorination of acidic or alkaline wastewater.

[0107] In the deep defluorination of low-concentration fluorine-containing wastewater from semiconductor and coking industries, under the same dosage conditions, the defluorination effect of the defluorinating agents of Examples 1 to 3 of the present invention is stronger than that of the conventional defluorinating agents of Comparative Examples 1 to 4. The defluorination rate of the defluorinating agents in Examples 1 to 3 for semiconductor fluorine-containing wastewater is not less than 83%, while the defluorination rate of Comparative Examples 1 to 4 does not exceed 79%; for fluorine-containing wastewater from the coking industry, the defluorination rate of the defluorinating agents in Examples 1 to 3 is not less than 93%, while the defluorination effect in Comparative Examples 1 to 4 is as low as 69.7% and does not exceed 89%.

[0108] Compared with Examples 1 to 3, the amount of acrylamide monomer used in Example 3 is higher, and the molecular weight of the obtained defluorinating agent is as high as 880,000, which means that the higher the molecular weight, the better the defluorination effect, and the stronger the role of promoting the chemical precipitation of fluoride ions from iron and aluminum in the defluorinating agent.

[0109] The defluorination effect of the defluorination agent prepared by simple raw material mixing in Comparative Example 4 is far inferior to that of the defluorination agent of the present invention. In the defluorination agent of the present invention, chemical bonds are formed between the metal elements Fe and Al and the organic cationic groups through polymerization reaction, and the defluorination effect is significantly improved.

[0110] In summary, the defluoridation agent of the present invention can achieve deep defluoridation of industrial fluorine-containing wastewater, the flocs generated during the defluoridation process are large and compact, the sedimentation speed is fast, and it has the advantages of a wide pH range of use and high removal efficiency, and can quickly reduce the fluoride ion concentration in the wastewater to below 1.0 mg / L, and still has a defluoridation rate of more than 80% for fluorine-containing wastewater with a concentration lower than 10 mg / L, the defluoridation agent has a low dosage, and an excellent defluoridation effect can be achieved at a dosage of less than 500 mg / L, and is suitable for the field of water treatment, especially for treating fluorine-containing wastewater. At the same time, the preparation method of the defluoridation agent of the present invention is simple and easy to operate, and the reaction aging time is short, the process cost is low, and mass production can be achieved.

[0111] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A defluorination agent, characterized in that: The preparation raw materials include: metal salt containing aluminum and iron, acrylamide monomer and cationic polymer monomer.

2. The defluorination agent according to claim 1, characterized in that The weight average molecular weight of the defluorination agent is 350,000 to 1,000,000.

3. The defluorination agent according to claim 1 or 2, characterized in that: The mass ratio of the acrylamide monomer to the cationic polymer monomer is 1:(1-4).

4. The defluorination agent according to claim 1 or 2, characterized in that: The mass fraction of aluminum oxide in the defluorination agent is 8-11%.

5. The defluorination agent according to claim 1 or 2, characterized in that: The raw material components of the defluorination agent also include an oxidant and a reducing agent; And / or, the amount of the reducing agent added is 0.15-2% of the total mass of the acrylamide monomer and the cationic polymer monomer; and / or, the amount of the oxidant added is 0.01-1% of the total mass of the acrylamide monomer and the cationic polymer monomer.

6. The defluorination agent according to claim 4, characterized in that: The cationic polymer monomer includes at least one of dimethyldiallylammonium chloride, methacryloyloxyethyltrimethylammonium chloride, and acryloyloxyethyltrimethylammonium chloride; And / or, the metal salt containing aluminum and iron includes aluminum ferric sulfate; And / or, the reducing agent includes at least one of sodium sulfite, sodium bisulfite, sodium pyrosulfite, and ammonium ferrous sulfate.

7. A method for preparing a defluorinating agent, characterized in that: The steps include: Acrylamide monomer and cationic polymer monomer are added to aluminum ferric sulfate solution to mix and dissolve, an oxidant is added, and then a reducing agent is added to carry out polymerization reaction to obtain the defluorination agent according to any one of claims 1 to 6.

8. The preparation method according to claim 7, characterized in that: The reducing agent is added in a dropwise manner, and the dropwise addition speed is 0.5 to 1.5 mL / min.

9. Use of the defluorinating agent according to any one of claims 1 to 6 or the defluorinating agent obtained by the preparation method according to any one of claims 7 to 8 in the field of water treatment.

10. The use according to claim 9, characterized in that: The water includes fluoride-containing wastewater; and / or, the fluoride ion concentration in the water is 1 to 10 mg / L; And / or, the pH of the water is 5 to 10; And / or, the amount of defluoridating agent used in the water treatment is 200-500 mg / L.

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