Acidic fluorine-containing wastewater treatment agent and use method thereof

Abstract

The invention relates to an acidic fluorine-containing wastewater treatment agent and a use method thereof, and relates to the technical field of fluorine-containing wastewater treatment.The acidic fluorine-containing wastewater treatment agent is prepared from, by weight, 30-50 parts of a core functional agent, 40-60 parts of a PH adjusting carrier, 10-20 parts of a synergistic agent and 3-5 parts of hyperbranched chitosan; the core functional agent is a modified polyaluminum chloride-quantum dot composite material; the PH adjusting carrier is roasted modified dolomite; the synergistic agent is prepared by mixing hydroxyapatite, a rare earth compound, hydroxypropyl beta-cyclodextrin and carboxymethyl chitosan according to a mass ratio of (8 to 10): (0.8 to 1.2): 1: (3 to 4). The agent has a remarkable treatment effect on fluorine-containing wastewater, and is high in fluorine removal efficiency and small in dosage.

Description

Technical Field

[0001] This invention relates to the field of fluoride-containing wastewater treatment technology, and in particular to a treatment agent for acidic fluoride-containing wastewater and its application method. Background Technology

[0002] The development of fluorochemicals has brought people high-value-added, high-performance fluorine products, but it has also brought a large amount of fluorine-containing pollutants. In particular, fluorine-containing wastewater needs special attention. If it is not treated and discharged in excess of standards, it will accumulate in soil and groundwater for a long time, posing a serious threat to the environment and human safety.

[0003] Currently, the mainstream technologies for treating acidic fluoride-containing wastewater include adsorption, membrane separation, and chemical precipitation. While adsorption is simple to operate, the high cost of adsorbent regeneration makes it difficult to apply to large-scale fluoride-containing wastewater treatment. Membrane separation offers high fluoride removal efficiency, but membrane modules are susceptible to corrosion by acidic wastewater, resulting in short service life and high maintenance costs. Chemical precipitation, while lower in cost and capable of handling large volumes, still suffers from technical drawbacks such as large suspension dosages and room for improvement in treatment effectiveness.

[0004] To address the aforementioned issues, Chinese invention patent CN118598305B discloses a treatment agent for acidic fluoride-containing wastewater and its application method. This treatment agent comprises Agent A and Agent B; Agent A includes carbonate and silicate minerals; Agent B is primarily aluminum salt. The application method of this treatment agent includes the following steps: (1) Pretreatment: sedimentation and filtration to remove suspended solids; (2) pH adjustment: adding Agent A to the acidic fluoride-containing wastewater to adjust the solution pH to 6.5-7.5; (3) Coagulation and sedimentation: adding Agent B to the solution, allowing it to settle after reaction, and then effluent is discharged. Using this treatment agent effectively improves the water's acid-base buffering capacity and spontaneously stabilizes the pH to 6.5-7.5, resulting in high fluoride removal efficiency. It also improves the settling efficiency of fluoride-removing flocs, avoids the use of polyacrylamide, and the treatment process is simple and inexpensive. However, the treatment agent is insufficient for treating wastewater with high fluoride concentrations and has poor tolerance to complex coexisting ions; the stability of the agent needs to be further improved.

[0005] It is evident that developing a treatment agent for acidic fluoride-containing wastewater that is highly effective, efficient in removing fluoride, and requires low dosage, along with its application method, meets market demand, has broad market value and application prospects, and is of great significance for promoting the development of the field of fluoride-containing wastewater treatment. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art by providing a treatment agent for acidic fluoride-containing wastewater that has a significant effect on the treatment of fluoride-containing wastewater, high fluoride removal efficiency, and low dosage, as well as its application method.

[0007] To achieve the above objectives, the technical solution adopted by this invention is: a treatment agent for acidic fluoride-containing wastewater, comprising the following raw materials in parts by weight: 30-50 parts of core functional agent, 40-60 parts of pH adjusting carrier, 10-20 parts of synergistic agent, and 3-5 parts of hyperbranched chitosan; wherein the core functional agent is a modified polyaluminum chloride-quantum dot composite material; the pH adjusting carrier is calcined modified dolomite; and the synergistic agent is hydroxyapatite, rare earth compounds, and hydroxypropyl... Cyclodextrin and carboxymethyl chitosan are mixed in a mass ratio of (8-10):(0.8-1.2):1:(3-4).

[0008] Preferably, the preparation method of the modified polyaluminum chloride-quantum dot composite material includes the following steps: adding polyaluminum chloride to deionized water, stirring evenly, then adding graphene oxide quantum dots, stirring and reacting at 60-80℃ for 2-3 hours, cooling and spray drying to obtain the modified polyaluminum chloride-quantum dot composite material.

[0009] Preferably, the polyaluminum chloride contains Content ≥30wt%, provided by Weifang Zhongqing Fine Chemical Co., Ltd.

[0010] Preferably, the mass ratio of the polyaluminum chloride, deionized water, and graphene oxide quantum dots is (10-20):100:(0.5-2).

[0011] Preferably, the graphene oxide quantum dots have 1-5 layers, a thickness of 1-2 nm, and a lateral dimension of 5-15 nm.

[0012] Preferably, the inlet air temperature of the spray dryer is 180-200℃ and the outlet air temperature is 80-100℃.

[0013] Preferably, the preparation method of the calcined modified dolomite includes the following steps: crushing the dolomite to a particle size ≤ 5 mm, heating it to 700-800 °C in a muffle furnace at a heating rate of 3-5 °C / min, holding it at the temperature for 2-3 h, and grinding it to a particle size ≤ 100 μm after natural cooling to obtain the calcined modified dolomite.

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

[0015] Preferably, the rare earth compound is at least one of scandium nitrate and lanthanum nitrate.

[0016] Preferably, the hydroxypropyl β-cyclodextrin has a molecular weight of 1541.54 and a degree of substitution of 5-8.

[0017] Preferably, the carboxymethyl chitosan has a degree of deacetylation ≥85% and a viscosity of 200-300. .

[0018] Preferably, there are no special requirements for the source of the hyperbranched chitosan. In one embodiment of the present invention, the hyperbranched chitosan is prepared according to the method of Chinese Invention Patent Example 2 with authorization announcement number CN100577688C.

[0019] Another object of the present invention is to provide a method for using the treatment agent for the acidic fluoride-containing wastewater, comprising the following steps:

[0020] Step S1, Pretreatment: Acidic fluoride-containing wastewater is passed through a screen to remove large particulate impurities, and then it is allowed to stand in a sedimentation tank for 1-2 hours to remove suspended solids, so that the suspended solids content in the wastewater is ≤50mg / L;

[0021] Step S2, reagent addition: Prepare a suspension by mixing the treatment reagent for acidic fluoride-containing wastewater with water at a mass ratio of 1:(5-10), and continuously add it to the pretreated wastewater through a metering pump. The amount of suspension added is 8-12 times the mass of fluoride ions.

[0022] Step S3, Reaction Stirring: Two-stage stirring is carried out in the reaction tank. The first stage is rapid stirring at a speed of 300-400 r / min for 5-10 min to ensure thorough mixing of the reagent and wastewater. The second stage is slow stirring at a speed of 50-100 r / min for 20-30 min to promote floc formation. Simultaneously, the fluorescence intensity of the reaction system is monitored in real time using a fluorescence spectrometer. When the fluorescence intensity drops to less than 10% of the initial value, the reaction is considered to have reached its endpoint.

[0023] Step S4, Sedimentation and Separation: The mixed liquid after reaction is sent to an inclined tube sedimentation tank and the retention time is 1-2 hours. The supernatant is the treated water, and the bottom sludge is dewatered by a plate and frame filter press and then transported for disposal.

[0024] Preferably, the aperture of the grille is 5mm.

[0025] Preferably, the excitation wavelength of the fluorescence spectrometer is 480 nm and the emission wavelength is 520 nm.

[0026] Due to the application of the above technical solution, the present invention has the following beneficial effects:

[0027] (1) The method of using the treatment agent for acidic fluoride-containing wastewater disclosed in this invention is simple, easy to construct, highly efficient, and has low dependence on equipment, and has high application value.

[0028] (2) The treatment agent for acidic fluoride-containing wastewater disclosed in this invention comprises the following raw materials in parts by weight: 30-50 parts of core functional agent, 40-60 parts of pH adjusting carrier, 10-20 parts of synergistic agent, and 3-5 parts of hyperbranched chitosan; wherein the core functional agent is a modified polyaluminum chloride-quantum dot composite material; the pH adjusting carrier is calcined modified dolomite; and the synergistic agent is hydroxyapatite, rare earth compounds, and hydroxypropyl. Cyclodextrin and carboxymethyl chitosan are mixed in a mass ratio of (8-10):(0.8-1.2):1:(3-4). Through the synergistic effect of the raw materials, the resulting treatment agent has a significant effect on the treatment of fluoride-containing wastewater, with high fluoride removal efficiency and low dosage. Detailed Implementation

[0029] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0030] Example 1

[0031] A treatment agent for acidic fluoride-containing wastewater comprises the following raw materials in parts by weight: 30 parts core functional agent, 40 parts pH adjusting carrier, 10 parts synergist, and 3 parts hyperbranched chitosan; wherein the core functional agent is a modified polyaluminum chloride-quantum dot composite material; the pH adjusting carrier is calcined modified dolomite; and the synergist is a mixture of hydroxyapatite, rare earth compounds, hydroxypropyl β-cyclodextrin, and carboxymethyl chitosan in a mass ratio of 8:0.8:1:3.

[0032] The preparation method of the modified polyaluminum chloride-quantum dot composite material includes the following steps: adding polyaluminum chloride to deionized water, stirring evenly, then adding graphene oxide quantum dots, stirring and reacting at 60°C for 2 hours, cooling, and spray drying to obtain the modified polyaluminum chloride-quantum dot composite material; wherein the polyaluminum chloride contains The content is ≥30wt%, provided by Weifang Zhongqing Fine Chemical Co., Ltd.; the mass ratio of the polyaluminum chloride, deionized water, and graphene oxide quantum dots is 10:100:0.5; the number of layers of the graphene oxide quantum dots is 1-5, the thickness is 1-2nm, and the lateral dimension is 5-15nm; the inlet air temperature of the spray dryer is 180℃, and the outlet air temperature is 80℃.

[0033] The preparation method of the calcined modified dolomite includes the following steps: crushing the dolomite to a particle size ≤ 5 mm, heating it to 700 °C in a muffle furnace at a heating rate of 3 °C / min, holding it at that temperature for 2 h, and grinding it to a particle size ≤ 100 μm after natural cooling to obtain the calcined modified dolomite; the average particle size of the hydroxyapatite is 1 μm.

[0034] The rare earth compound is scandium nitrate; the hydroxypropyl... The cyclodextrin has a molecular weight of 1541.54 and a degree of substitution of 5; the carboxymethyl chitosan has a degree of deacetylation ≥85% and a viscosity of 200. The hyperbranched chitosan was prepared according to the method of Example 2 of Chinese Invention Patent No. CN100577688C.

[0035] A method for using a treatment agent for acidic fluoride-containing wastewater includes the following steps:

[0036] Step S1, Pretreatment: Acidic fluoride-containing wastewater is passed through a screen to remove large particulate impurities, and then allowed to settle in a sedimentation tank for 1-2 hours to remove suspended solids, so that the suspended solids content in the wastewater is ≤50mg / L; the screen has a pore size of 5mm.

[0037] Step S2, reagent addition: Prepare a suspension by mixing the treatment reagent for acidic fluoride-containing wastewater with water at a mass ratio of 1:10. Add the suspension continuously to the pretreated wastewater using a metering pump. The amount of suspension added is 8 times the mass of fluoride ions.

[0038] Step S3, Reaction Stirring: Two-stage stirring is carried out in the reaction tank. The first stage is rapid stirring at 300 r / min for 5 min to ensure thorough mixing of the reagent and wastewater. The second stage is slow stirring at 50 r / min for 20 min to promote floc formation. Simultaneously, the fluorescence intensity of the reaction system is monitored in real time using a fluorescence spectrometer. When the fluorescence intensity drops to less than 10% of the initial value, the reaction is considered to have reached its endpoint. The excitation wavelength of the fluorescence spectrometer is 480 nm, and the emission wavelength is 520 nm.

[0039] Step S4, Sedimentation and Separation: The mixed liquid after reaction is sent to an inclined tube sedimentation tank and retained for 1 hour. The supernatant is the treated water, and the bottom sludge is dewatered by a plate and frame filter press and then transported off-site for disposal.

[0040] Example 2

[0041] A treatment agent for acidic fluoride-containing wastewater comprises the following raw materials in parts by weight: 35 parts core functional agent, 45 parts pH adjusting carrier, 13 parts synergist, and 3.5 parts hyperbranched chitosan; wherein the core functional agent is a modified polyaluminum chloride-quantum dot composite material; the pH adjusting carrier is calcined modified dolomite; and the synergist is hydroxyapatite, rare earth compounds, and hydroxypropyl... Cyclodextrin and carboxymethyl chitosan were mixed in a mass ratio of 8.5:0.9:1:3.2.

[0042] The preparation method of the modified polyaluminum chloride-quantum dot composite material includes the following steps: adding polyaluminum chloride to deionized water, stirring evenly, then adding graphene oxide quantum dots, stirring and reacting at 65°C for 2.3 hours, cooling, and spray drying to obtain the modified polyaluminum chloride-quantum dot composite material; wherein the polyaluminum chloride contains The content is ≥30wt%, provided by Weifang Zhongqing Fine Chemical Co., Ltd.; the mass ratio of the polyaluminum chloride, deionized water, and graphene oxide quantum dots is 13:100:1; the number of layers of the graphene oxide quantum dots is 1-5, the thickness is 1-2nm, and the lateral dimension is 5-15nm; the inlet air temperature of the spray dryer is 185℃, and the outlet air temperature is 85℃.

[0043] The preparation method of the calcined modified dolomite includes the following steps: crushing dolomite to a particle size ≤ 5 mm, heating it to 730 °C in a muffle furnace at a heating rate of 3.5 °C / min, holding it at that temperature for 2.3 h, and then grinding it to a particle size ≤ 100 μm after natural cooling to obtain calcined modified dolomite; the average particle size of the hydroxyapatite is 2 μm; the rare earth compound is lanthanum nitrate; the molecular weight of the hydroxypropyl β-cyclodextrin is 1541.54, and the degree of substitution is 6; the degree of deacetylation of the carboxymethyl chitosan is ≥ 85%, and the viscosity is 230. The hyperbranched chitosan was prepared according to the method of Example 2 of Chinese Invention Patent No. CN100577688C.

[0044] A method for using a treatment agent for acidic fluoride-containing wastewater includes the following steps:

[0045] Step S1, Pretreatment: Acidic fluoride-containing wastewater is passed through a screen to remove large particulate impurities, and then allowed to settle in a sedimentation tank for 1.2 hours to remove suspended solids, so that the suspended solids content in the wastewater is ≤50mg / L; the screen has a pore size of 5mm.

[0046] Step S2, reagent addition: Prepare a suspension by mixing the treatment reagent for acidic fluoride-containing wastewater with water at a mass ratio of 1:10. Add the suspension continuously to the pretreated wastewater using a metering pump. The amount of suspension added is 8 times the mass of fluoride ions.

[0047] Step S3, Reaction Stirring: Two-stage stirring is carried out in the reaction tank. The first stage is rapid stirring at 330 r / min for 6 min to ensure thorough mixing of the reagent and wastewater. The second stage is slow stirring at 70 r / min for 23 min to promote floc formation. Simultaneously, the fluorescence intensity of the reaction system is monitored in real time using a fluorescence spectrometer. When the fluorescence intensity drops to less than 10% of the initial value, the reaction is considered to have reached its endpoint. The excitation wavelength of the fluorescence spectrometer is 480 nm, and the emission wavelength is 520 nm.

[0048] Step S4, Sedimentation and Separation: The mixed liquid after reaction is sent to an inclined tube sedimentation tank and retained for 1.2 hours. The supernatant is the treated water, and the bottom sludge is dewatered by a plate and frame filter press and then transported off-site for disposal.

[0049] Example 3

[0050] A treatment agent for acidic fluoride-containing wastewater comprises the following raw materials in parts by weight: 40 parts core functional agent, 50 parts pH adjusting carrier, 15 parts synergist, and 4 parts hyperbranched chitosan; wherein the core functional agent is a modified polyaluminum chloride-quantum dot composite material; the pH adjusting carrier is calcined modified dolomite; and the synergist is hydroxyapatite, rare earth compounds, and hydroxypropyl... Cyclodextrin and carboxymethyl chitosan were mixed in a mass ratio of 9:1:1:3.5.

[0051] The preparation method of the modified polyaluminum chloride-quantum dot composite material includes the following steps: adding polyaluminum chloride to deionized water, stirring evenly, then adding graphene oxide quantum dots, stirring and reacting at 70°C for 2.5 h, cooling, and spray drying to obtain the modified polyaluminum chloride-quantum dot composite material; wherein the polyaluminum chloride contains The content is ≥30wt%, provided by Weifang Zhongqing Fine Chemical Co., Ltd.; the mass ratio of the polyaluminum chloride, deionized water, and graphene oxide quantum dots is 15:100:1.3; the number of layers of the graphene oxide quantum dots is 1-5, the thickness is 1-2nm, and the lateral dimension is 5-15nm; the inlet air temperature of the spray dryer is 190℃, and the outlet air temperature is 90℃.

[0052] The preparation method of the calcined modified dolomite includes the following steps: crushing dolomite to a particle size ≤ 5 mm, heating it to 750 °C in a muffle furnace at a heating rate of 4 °C / min, holding it at that temperature for 2.5 h, and then grinding it to a particle size ≤ 100 μm after natural cooling to obtain calcined modified dolomite; the average particle size of the hydroxyapatite is 3.5 μm; the rare earth compound is scandium nitrate; the molecular weight of the hydroxypropyl β-cyclodextrin is 1541.54, and the degree of substitution is 6.5; the degree of deacetylation of the carboxymethyl chitosan is ≥ 85%, and the viscosity is 250. The hyperbranched chitosan was prepared according to the method of Example 2 of Chinese Invention Patent No. CN100577688C.

[0053] A method for using a treatment agent for acidic fluoride-containing wastewater includes the following steps:

[0054] Step S1, Pretreatment: Acidic fluoride-containing wastewater is passed through a screen to remove large particulate impurities, and then allowed to settle in a sedimentation tank for 1.5 hours to remove suspended solids, so that the suspended solids content in the wastewater is ≤50mg / L; the screen has a pore size of 5mm.

[0055] Step S2, reagent addition: Prepare a suspension by mixing the treatment reagent for acidic fluoride-containing wastewater with water at a mass ratio of 1:10. Add the suspension continuously to the pretreated wastewater using a metering pump. The amount of suspension added is 8 times the mass of fluoride ions.

[0056] Step S3, Reaction Stirring: Two-stage stirring is carried out in the reaction tank. The first stage is rapid stirring at 350 r / min for 8 min to ensure thorough mixing of the reagent and wastewater. The second stage is slow stirring at 80 r / min for 25 min to promote floc formation. Simultaneously, the fluorescence intensity of the reaction system is monitored in real time using a fluorescence spectrometer. When the fluorescence intensity drops to less than 10% of the initial value, the reaction is considered to have reached its endpoint. The excitation wavelength of the fluorescence spectrometer is 480 nm, and the emission wavelength is 520 nm.

[0057] Step S4, Sedimentation and Separation: The mixed liquid after reaction is sent to an inclined tube sedimentation tank and retained for 1.5 hours. The supernatant is the treated water, and the bottom sludge is dewatered by a plate and frame filter press and then transported off-site for disposal.

[0058] Example 4

[0059] A treatment agent for acidic fluoride-containing wastewater comprises the following raw materials in parts by weight: 45 parts core functional agent, 55 parts pH adjusting carrier, 18 parts synergist, and 4.5 parts hyperbranched chitosan; wherein the core functional agent is a modified polyaluminum chloride-quantum dot composite material; the pH adjusting carrier is calcined modified dolomite; and the synergist is a mixture of hydroxyapatite, rare earth compounds, hydroxypropyl β-cyclodextrin, and carboxymethyl chitosan in a mass ratio of 9.5:1.1:1:3.8.

[0060] The preparation method of the modified polyaluminum chloride-quantum dot composite material includes the following steps: adding polyaluminum chloride to deionized water, stirring evenly, then adding graphene oxide quantum dots, stirring and reacting at 75°C for 2.8 h, cooling, and spray drying to obtain the modified polyaluminum chloride-quantum dot composite material; wherein the polyaluminum chloride contains The content is ≥30wt%, provided by Weifang Zhongqing Fine Chemical Co., Ltd.; the mass ratio of the polyaluminum chloride, deionized water, and graphene oxide quantum dots is 18:100:1.8; the number of layers of the graphene oxide quantum dots is 1-5, the thickness is 1-2nm, and the lateral dimension is 5-15nm; the inlet air temperature of the spray dryer is 195℃, and the outlet air temperature is 95℃.

[0061] The preparation method of the calcined modified dolomite includes the following steps: crushing dolomite to a particle size ≤ 5 mm, heating it to 780 °C in a muffle furnace at a heating rate of 4.5 °C / min, holding it at that temperature for 2.8 h, and then grinding it to a particle size ≤ 100 μm after natural cooling to obtain calcined modified dolomite; the average particle size of the hydroxyapatite is 4 μm; the rare earth compound is a mixture of scandium nitrate and lanthanum nitrate in a mass ratio of 3:5; the hydroxypropyl... The cyclodextrin has a molecular weight of 1541.54 and a degree of substitution of 7.5; the carboxymethyl chitosan has a degree of deacetylation ≥85% and a viscosity of 290. The hyperbranched chitosan was prepared according to the method of Example 2 of Chinese Invention Patent No. CN100577688C.

[0062] A method for using a treatment agent for acidic fluoride-containing wastewater includes the following steps:

[0063] Step S1, Pretreatment: Acidic fluoride-containing wastewater is passed through a screen to remove large particulate impurities, and then allowed to settle in a sedimentation tank for 1.8 hours to remove suspended solids, so that the suspended solids content in the wastewater is ≤50mg / L; the screen has a pore size of 5mm.

[0064] Step S2, reagent addition: Prepare a suspension by mixing the treatment reagent for acidic fluoride-containing wastewater with water at a mass ratio of 1:10. Add the suspension continuously to the pretreated wastewater using a metering pump. The amount of suspension added is 8 times the mass of fluoride ions.

[0065] Step S3, Reaction Stirring: Two-stage stirring is carried out in the reaction tank. The first stage is rapid stirring at 380 r / min for 9 min to ensure thorough mixing of the reagent and wastewater. The second stage is slow stirring at 90 r / min for 29 min to promote floc formation. Simultaneously, the fluorescence intensity of the reaction system is monitored in real time using a fluorescence spectrometer. When the fluorescence intensity drops below 10% of the initial value, the reaction is considered to have reached its endpoint. The excitation wavelength of the fluorescence spectrometer is 480 nm, and the emission wavelength is 520 nm.

[0066] Step S4, Sedimentation and Separation: The mixed liquid after reaction is sent to an inclined tube sedimentation tank and the residence time is 1.8 hours. The supernatant is the treated water, and the bottom sludge is dewatered by a plate and frame filter press and then transported for disposal.

[0067] Example 5

[0068] A treatment agent for acidic fluoride-containing wastewater comprises the following raw materials in parts by weight: 50 parts core functional agent, 60 parts pH adjusting carrier, 20 parts synergist, and 5 parts hyperbranched chitosan; wherein the core functional agent is a modified polyaluminum chloride-quantum dot composite material; the pH adjusting carrier is calcined modified dolomite; and the synergist is hydroxyapatite, rare earth compounds, and hydroxypropyl... Cyclodextrin and carboxymethyl chitosan were mixed in a mass ratio of 10:1.2:1:4.

[0069] The preparation method of the modified polyaluminum chloride-quantum dot composite material includes the following steps: adding polyaluminum chloride to deionized water, stirring evenly, then adding graphene oxide quantum dots, stirring and reacting at 80°C for 3 hours, cooling, and spray drying to obtain the modified polyaluminum chloride-quantum dot composite material; wherein the polyaluminum chloride contains The content is ≥30wt%, provided by Weifang Zhongqing Fine Chemical Co., Ltd.; the mass ratio of the polyaluminum chloride, deionized water, and graphene oxide quantum dots is 20:100:2; the number of layers of the graphene oxide quantum dots is 1-5, the thickness is 1-2nm, and the lateral dimension is 5-15nm; the inlet air temperature of the spray dryer is 200℃, and the outlet air temperature is 100℃.

[0070] The preparation method of the calcined modified dolomite includes the following steps: crushing dolomite to a particle size ≤ 5 mm, heating it to 800 °C in a muffle furnace at a heating rate of 5 °C / min, holding it at that temperature for 3 h, and then grinding it to a particle size ≤ 100 μm after natural cooling to obtain calcined modified dolomite; the average particle size of the hydroxyapatite is 5 μm; the rare earth compound is scandium nitrate; the hydroxypropyl... The cyclodextrin has a molecular weight of 1541.54 and a degree of substitution of 8; the carboxymethyl chitosan has a degree of deacetylation ≥85% and a viscosity of 300. The hyperbranched chitosan was prepared according to the method of Example 2 of Chinese Invention Patent No. CN100577688C.

[0071] A method for using a treatment agent for acidic fluoride-containing wastewater includes the following steps:

[0072] Step S1, Pretreatment: Acidic fluoride-containing wastewater is passed through a screen to remove large particulate impurities, and then allowed to settle in a sedimentation tank for 2 hours to remove suspended solids, so that the suspended solids content in the wastewater is ≤50mg / L; the screen has a pore size of 5mm.

[0073] Step S2, reagent addition: Prepare a suspension by mixing the treatment reagent for acidic fluoride-containing wastewater with water at a mass ratio of 1:10. Add the suspension continuously to the pretreated wastewater using a metering pump. The amount of suspension added is 8 times the mass of fluoride ions.

[0074] Step S3, Reaction Stirring: Two-stage stirring is carried out in the reaction tank. The first stage is rapid stirring at 400 r / min for 10 min to ensure thorough mixing of the reagent and wastewater. The second stage is slow stirring at 100 r / min for 30 min to promote floc formation. Simultaneously, the fluorescence intensity of the reaction system is monitored in real time using a fluorescence spectrometer. When the fluorescence intensity drops below 10% of the initial value, the reaction is considered to have reached its endpoint. The excitation wavelength of the fluorescence spectrometer is 480 nm, and the emission wavelength is 520 nm.

[0075] Step S4, Sedimentation and Separation: The mixed liquid after reaction is sent to an inclined tube sedimentation tank and retained for 2 hours. The supernatant is the treated water, and the bottom sludge is dewatered by a plate and frame filter press and then transported off-site for disposal.

[0076] Comparative Example 1

[0077] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as in Example 1, except that rare earth compounds and hydroxypropyl β-cyclodextrin are not added.

[0078] Comparative Example 2

[0079] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as in Example 1, except that an equal amount of polyaluminum chloride is used instead of the modified polyaluminum chloride-quantum dot composite material.

[0080] Comparative Example 3

[0081] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as in Example 1, except that an equal amount of hyperbranched chitosan is used instead of rare earth compounds.

[0082] Comparative Example 4

[0083] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as in Example 1, except that an equal amount of rare earth compounds are used instead of hyperbranched chitosan.

[0084] Comparative Example 5

[0085] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as in Example 1, except that an equal amount of hydroxypropyl β-cyclodextrin is used instead of hyperbranched chitosan.

[0086] Comparative Example 6

[0087] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as in Example 1, except that an equal amount of hyperbranched chitosan is used instead of hydroxypropyl β-cyclodextrin.

[0088] Comparative Example 7

[0089] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as in Example 1, except that an equal amount of hyperbranched chitosan is used instead of carboxymethyl chitosan.

[0090] Comparative Example 8

[0091] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as in Example 1, except that an equal amount of carboxymethyl chitosan is used instead of hyperbranched chitosan.

[0092] Comparative Example 9

[0093] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as in Example 1, except that an equal amount of hydroxypropyl-modified polyaluminum chloride-quantum dot composite material is used instead of hyperbranched chitosan.

[0094] Comparative Example 10

[0095] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as in Example 1, except that an equal amount of hyperbranched chitosan is used instead of the modified polyaluminum chloride-quantum dot composite material.

[0096] Comparative Example 11

[0097] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as in Example 1, except that an equal amount of rare earth compound is used instead of hydroxypropyl β-cyclodextrin.

[0098] Comparative Example 12

[0099] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as in Example 1, except that an equal amount of hydroxypropyl β-cyclodextrin is used instead of rare earth compounds.

[0100] Comparative Example 13

[0101] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as that in Example 1, except that an equal amount of hydroxypropyl β-cyclodextrin is used instead of graphene oxide quantum dots.

[0102] Comparative Example 14

[0103] This example provides a treatment agent for acidic fluoride-containing wastewater and its application method, which is basically the same as in Example 1, except that an equal amount of rare earth compounds are used instead of graphene oxide quantum dots. To further illustrate the beneficial technical effects of the treatment agents and application methods for acidic fluoride-containing wastewater involved in the various embodiments of the present invention, the following experiments were conducted on the products and application methods of each example:

[0104] Original wastewater quality: Acidic fluoride-containing wastewater from a non-ferrous metal smelting plant in Inner Mongolia, pH=2.5, fluoride ion concentration 800mg / L. Concentration 500 mg / L The concentration was 800 mg / L, and SS was 80 mg / L. Wastewater was treated according to the methods in Examples 1-5 and Comparative Examples 1-2. The concentration of fluoride ions and the COD value in the treated water were measured. The detection of fluoride ion concentration was in accordance with GB / T7484-1987, and the detection of COD value was in accordance with HJ / T 399-2007 "Determination of Chemical Oxygen Demand in Water - Rapid Digestion Spectrophotometric Method". The test results are shown in Table 1.

[0105] Table 1

[0106]

[0107] As can be seen from Table 1, the treatment agents and their application methods for acidic fluoride-containing wastewater disclosed in the embodiments of the present invention have better fluoride-containing wastewater treatment effects than the comparative examples. The combined use of rare earth compounds, hydroxypropyl β-cyclodextrin, modified polyaluminum chloride-quantum dot composite materials, hyperbranched chitosan, carboxymethyl chitosan and graphene oxide quantum dots is beneficial to improving the above performance; there are interactions among these components.

[0108] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A treatment agent for acidic fluoride-containing wastewater, characterized in that, The product comprises the following raw materials in parts by weight: 30-50 parts core functional agent, 40-60 parts pH adjusting carrier, 10-20 parts synergist, and 3-5 parts hyperbranched chitosan; the core functional agent is a modified polyaluminum chloride-quantum dot composite material; the pH adjusting carrier is calcined modified dolomite; and the synergist is a mixture of hydroxyapatite, rare earth compounds, hydroxypropyl β-cyclodextrin, and carboxymethyl chitosan in a mass ratio of (8-10):(0.8-1.2):1:(3-4).

2. The treatment agent for acidic fluoride-containing wastewater according to claim 1, characterized in that, The preparation method of the modified polyaluminum chloride-quantum dot composite material includes the following steps: adding polyaluminum chloride to deionized water, stirring evenly, then adding graphene oxide quantum dots, stirring and reacting at 60-80℃ for 2-3 hours, cooling and spray drying to obtain the modified polyaluminum chloride-quantum dot composite material.

3. The treatment agent for acidic fluoride-containing wastewater according to claim 2, characterized in that, The polyaluminum chloride contains ≥30wt% Al2O3; the mass ratio of the polyaluminum chloride, deionized water, and graphene oxide quantum dots is (10-20):100:(0.5-2).

4. The treatment agent for acidic fluoride-containing wastewater according to claim 2, characterized in that, - The number of layers of the graphene oxide quantum dots is 1-5, the thickness is 1-2nm, and the lateral dimension is 5-15nm; the inlet air temperature of the spray dryer is 180-200℃, and the outlet air temperature is 80-100℃.

5. The treatment agent for acidic fluoride-containing wastewater according to claim 1, characterized in that, The preparation method of the calcined modified dolomite includes the following steps: crushing dolomite to a particle size ≤ 5 mm, heating it to 700-800 °C in a muffle furnace at a heating rate of 3-5 °C / min, holding it at the temperature for 2-3 h, and grinding it to a particle size ≤ 100 μm after natural cooling to obtain calcined modified dolomite.

6. The treatment agent for acidic fluoride-containing wastewater according to claim 1, characterized in that, The average particle size of the hydroxyapatite is 1-5 μm; the rare earth compound is at least one of scandium nitrate and lanthanum nitrate.

7. The treatment agent for acidic fluoride-containing wastewater according to claim 1, characterized in that, The hydroxypropyl β-cyclodextrin has a molecular weight of 1541.54 and a degree of substitution of 5-8; the carboxymethyl chitosan has a degree of deacetylation ≥85% and a viscosity of 200-300 mPa·s.

8. A method of using the treatment agent for acidic fluoride-containing wastewater according to any one of claims 1-7, characterized in that, Includes the following steps: Step S1, Pretreatment: Acidic fluoride-containing wastewater is passed through a screen to remove large particulate impurities, and then it is allowed to stand in a sedimentation tank for 1-2 hours to remove suspended solids, so that the suspended solids content in the wastewater is ≤50mg / L; Step S2, reagent addition: Prepare a suspension by mixing the treatment reagent for acidic fluoride-containing wastewater with water at a mass ratio of 1:(5-10), and continuously add it to the pretreated wastewater through a metering pump. The amount of suspension added is 8-12 times the mass of fluoride ions. Step S3, reaction stirring: Two-stage stirring is carried out in the reaction tank. The first stage is rapid stirring at a speed of 300-400 r / min for 5-10 min to ensure that the reagent and wastewater are fully mixed. The second stage involves slow stirring at a speed of 50-100 r / min for 20-30 min to promote floc formation. Simultaneously, the fluorescence intensity of the reaction system is monitored in real time using a fluorescence spectrometer. When the fluorescence intensity drops to less than 10% of the initial value, the reaction is considered to have reached its endpoint. Step S4, Sedimentation and Separation: The mixed liquid after reaction is sent to an inclined tube sedimentation tank and the retention time is 1-2 hours. The supernatant is the treated water, and the bottom sludge is dewatered by a plate and frame filter press and then transported for disposal.

9. The method of using the treatment agent for acidic fluoride-containing wastewater according to claim 8, characterized in that, The aperture of the grille is 5mm.

10. The method of using the treatment agent for acidic fluoride-containing wastewater according to claim 8, characterized in that, The fluorescence spectrometer has an excitation wavelength of 480 nm and an emission wavelength of 520 nm.

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