Functionalized polyacrylamide for aluminum oxide production and preparation method thereof
Functionalized polyacrylamide was prepared by copolymerizing polyamine groups on the main chain of polyacrylamide, which solved the problem of fluoride removal in alumina production, achieved the multi-effect fluoride adsorption of a highly efficient flocculant, and simplified the fluoride removal process.
Patent Information
- Application Number
- CN202511322849.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-16
- Publication Date
- 2025-12-16
AI Technical Summary
Existing polyacrylamide cannot effectively remove fluoride in alumina production, resulting in excessive fluoride content in wastewater, which increases production costs and process complexity.
Functionalized polyacrylamide was prepared by copolymerizing polyamine groups on the main chain of polyacrylamide and forming multidentate hydrogen bonds between positively charged nitrogen atoms and fluoride ions. This functionalized polyacrylamide can be used as a flocculant to simultaneously adsorb fluoride ions.
It achieves efficient removal of fluoride from wastewater in alumina production, reducing the fluoride content to below 10 ppm, simplifying the defluorination process, and improving water treatment efficiency.
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Figure CN121135941A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polyacrylamide, and more particularly to a functionalized polyacrylamide for alumina production and its preparation method, used in the alumina preparation process. Background Technology
[0002] Polyacrylamide (PAM) is a common water treatment agent, and its excellent flocculation performance is particularly prominent in water treatment due to its high molecular weight and strong polarity. In the alumina preparation process, PAM is mainly used as a high-efficiency flocculant, and its core purpose is to accelerate the solid-liquid separation process through charge neutralization and adsorption bridging. In the red mud settling separation stage (a core step of the Bayer process), after bauxite is leached under high pressure, a slurry containing red mud (mainly composed of Fe2O3, SiO2, etc.) is formed. PAM can accelerate the settling of red mud: PAM adsorbs red mud particles to form flocs, which can increase the settling speed by 3 to 5 times. It can also reduce the liquid-to-solid ratio of the underflow, reducing the liquid-to-solid ratio (L / S) of the underflow red mud from the initial 4 to 5 to 1.5 to 2.0, while improving the transparency of the supernatant and reducing suspended solids (SS) to ≤100 mg / L, ensuring the subsequent decomposition process. In the red mud washing process, polyacrylamide can improve washing efficiency, reduce the loss of NaOH and Al2O3 in the red mud adsorbate, and reduce the number of washing cycles. Through enhanced flocculation, the number of washing cycles can be reduced from 6-8 times to 4-5 times. In the circulating water treatment process, polyacrylamide can remove suspended solids, reduce SS to ≤30mg / L, and at the same time reduce pipe scaling and inhibit the deposition of fine particles in the circulating system.
[0003] However, common anionic polyacrylamide used as a flocculant has no significant effect on fluoride removal in alumina production. In alumina preparation processes, the application of fluoride is mainly related to the sintering method, while in water treatment, the fluoride concentration must be strictly controlled to ≤10 mg / L. Aluminum fluoride (AlF3) or sodium fluoride (NaF) is typically added as a flux to lower the melting point of the ore and promote the formation of sodium aluminate (NaAlO2); it can also react with silicates to form sodium fluorosilicate (Na2SiF6), reducing the interference of silicon impurities on the process and increasing the alumina dissolution rate in bauxite.
[0004] Therefore, fluoride-containing wastewater is generated during the sintering process, wet defluorination of flue gas, and equipment flushing. The fluoride content in sintering wastewater is generally 150–500 ppm, while in wet defluorination of flue gas it is approximately 200–600 ppm. According to the "Integrated Wastewater Discharge Standard" (GB 8978-1996), fluoride (calculated as F-) should be ≤10 mg / L. If the wastewater is recycled, the fluoride concentration needs to be controlled to ≤5 mg / L to prevent pipe corrosion and scaling. Common defluorination technologies include chemical precipitation (adding lime (CaO) to generate calcium fluoride (CaF2) precipitate), adsorption (using activated alumina, zeolite, etc.), and membrane separation (reverse osmosis (RO) or electrodialysis (ED)). Polyacrylamide, a commonly used flocculant in alumina production, can significantly improve water treatment efficiency and reduce production process complexity and costs if it can also effectively remove fluoride. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a functionalized polyacrylamide that can efficiently chelate fluorine in alumina production and its preparation method.
[0006] The present invention designs a polymer monomer containing polyamine groups, which is incorporated into the main chain of polyacrylamide through free radical polymerization. On the monomer with polyamine groups, the positively charged nitrogen atoms form multidentate hydrogen bonds with F-, which can effectively enrich fluorine elements on the polymer chain. While acting as a flocculant, it can also efficiently adsorb fluorine in water and reduce the fluorine content in wastewater.
[0007] This invention is achieved through the following technical solution:
[0008] On the one hand, a functionalized polyacrylamide is provided, which is obtained by copolymerization of acrylamide structural monomer, anionic structural monomer and polyamine monomer; wherein the polyamine monomer accounts for 15% to 25% of the total mass of the polymerization unit; and the anionic structural monomer accounts for 60% to 75% of the total mass of the polymerization unit.
[0009] Furthermore, the structural formula of the functionalized polyacrylamide is shown in the figure below:
[0010]
[0011] Where a, b, and c are all natural numbers greater than or equal to 1; R1 is an anionic monomer; and R2 is a polyamine monomer.
[0012] Furthermore, R2 is one of the side groups containing the following groups:
[0013]
[0014] Furthermore, the anionic monomer is acrylic acid.
[0015] On the other hand, a method for preparing functionalized polyacrylamide is provided, comprising the following steps:
[0016] Step 1: Material preparation: Weigh 10-15 parts of acrylamide structural monomer, 60-75 parts of anionic structural monomer, 15-25 parts of polyamine monomer, 0.002-0.05 parts of disodium ethylenediaminetetraacetate, 0.00002-0.0005 parts of oxidant, 0.00004-0.0007 parts of reducing agent, and 60-90 parts of deionized water;
[0017] Step 2: Mixing: Add the acrylamide structural monomer, anionic monomer, polyamine monomer, and disodium ethylenediaminetetraacetate to deionized water according to the above formula to prepare a homogeneous solution. Adjust the pH value to between 6.5 and 7.5 with sodium hydroxide to obtain the mixed solution.
[0018] Step 3 Deoxygenation: Cool the mixture obtained in Step 2 to -2 to 0℃, transfer it to an insulated container, and purge it with nitrogen for 30 minutes;
[0019] Step 4 Polymerization: Prepare solutions of the oxidant and reducing agent described in Step 1, add them to the reaction system, purge with nitrogen until the system begins to heat up, and keep warm for 2 hours after the heating is complete;
[0020] Step 5: Pulverization: The obtained colloid is granulated, dried, and pulverized to obtain the final product.
[0021] As a preferred embodiment, the polyamine monomer is synthesized by the following method:
[0022] Acryloyl chloride and biguanide were dissolved in a mixed solution of acetone and triethylamine and reacted at 25°C for 1–5 hours. The molar ratio of acryloyl chloride to biguanide was 1:1.2, and the mass ratio of acetone to triethylamine was 2:1. The reactants were distilled to remove the solvent and excess unreacted monomers to obtain polyamine monomers.
[0023] The mechanism for synthesizing polyamine monomers from biguanide is as follows, wherein the acyl chloride reacts randomly with any hydrogen atom on the ammonia-containing compound.
[0024]
[0025] As a preferred embodiment, the polyamine monomer is synthesized by the following method:
[0026] Acryloyl chloride and tetraethylenepentamine were dissolved in a mixed solution of acetone and triethylamine and reacted at 25°C for 1–5 hours. The molar ratio of acryloyl chloride to tetraethylenepentamine was 1:1.2, and the mass ratio of acetone to triethylamine was 2:1. The reactants were distilled to remove the solvent and excess unreacted monomers to obtain polyamine monomers.
[0027] The mechanism for synthesizing polyamine monomers from tetraethylenepentamine is as follows:
[0028]
[0029] Preferably, the anionic monomer is acrylic acid.
[0030] Furthermore, the oxidant is at least one of potassium bromate, potassium persulfate, and sodium persulfate.
[0031] Furthermore, the reducing agent is at least one of sodium bisulfite, sodium dithionite, and sodium metabisulfite.
[0032] The functionalized polyacrylamide prepared by the above method can be used in alumina production as a flocculant to flocculate suspended ions in red mud, while effectively enriching fluoride ions in water and removing fluoride from the water.
[0033] Specifically, when functionalized polyacrylamide is applied at a concentration of 3000 ppm, and is used at a volume ratio of 1:1 to treat a fluorine-containing solution containing 600 ppm, the fluorine content can be reduced to below 10 ppm.
[0034] The beneficial effects of this invention are:
[0035] This invention introduces a polymeric monomer containing polyamine groups into the main chain of polyacrylamide via free radical polymerization. On the monomer with polyamine groups, the positively charged nitrogen atom forms a multidentate hydrogen bond with F-, which can effectively enrich fluorine in the polymer chain. In alumina production, it acts as a flocculant while efficiently adsorbing fluorine in water, reducing the fluorine content in wastewater, achieving multiple effects with one agent, and simplifying the defluorination section in the later process. Attached Figure Description
[0036] Figure 1 The present invention is a hydrogen nuclear magnetic resonance spectrum of the functionalized polyacrylamide in Example 1. The chemical structure of Example 2 is the same as that of Example 1, and the nuclear magnetic resonance spectrum is not provided again.
[0037] Figure 2 The present invention provides the proton NMR spectrum of the functionalized polyacrylamide in Example 3. The chemical structure of Example 4 is the same as that of Example 3, and the NMR spectrum is not provided again. Detailed Implementation
[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0039] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, all percentages, ratios, proportions, or parts are by weight.
[0040] Unless otherwise specified, the reagents and raw materials used in the embodiments and comparative examples of this invention are commercially available.
[0041] Example 1
[0042] A functionalized polyacrylamide for alumina production is prepared by copolymerization of acrylamide, polyamine monomer and acrylic acid, and its structural formula is shown in the figure below.
[0043]
[0044] Where a, b, and c are all natural numbers greater than or equal to 1.
[0045] A method for preparing the above-mentioned functionalized polyacrylamide includes the following steps:
[0046] First, prepare monomers with polyamine groups:
[0047] Biguanide and acryloyl chloride were reacted in a mixed solution of acetone and triethylamine at 25°C for 5 hours; wherein the molar ratio of acryloyl chloride to biguanide was 1:1.2 and the mass ratio of acetone to triethylamine was 2:1.
[0048] The reactants were distilled to remove the solvent and excess unreacted monomers, yielding polyamine monomers.
[0049] The reaction mechanism is as follows:
[0050]
[0051] Then weigh out 15 parts acrylamide, 60 parts acrylic acid, 25 parts of the above polyamine monomer, 0.002 parts disodium ethylenediaminetetraacetate, 0.00002 parts potassium persulfate, 0.00004 parts sodium bisulfite and 60 parts deionized water;
[0052] Acrylamide, acrylic acid, polyamine monomer, and disodium ethylenediaminetetraacetate were added to deionized water to prepare a homogeneous solution, and the pH was adjusted to between 6.5 and 7.5 with sodium hydroxide.
[0053] Prepare 1% aqueous solutions of potassium persulfate and sodium bisulfite respectively;
[0054] Cool the resulting mixture to -2 to 0°C, transfer it to an insulated container, and purge with nitrogen for 30 minutes to remove oxygen from the reaction system.
[0055] Potassium persulfate and sodium bisulfite were added to the reaction system in sequence, and nitrogen gas was purged until the system began to heat up. After the heating was completed, the system was kept at the temperature for 2 hours, and the colloidal product was collected.
[0056] The obtained colloid can be pelletized, dried, and pulverized to obtain functionalized polyacrylamide.
[0057] The proton NMR spectrum of the functionalized polyacrylamide is shown below. Figure 1 As shown, the highest peak is the solvent peak of water. Since active hydrogen does not produce a peak in water, the hydrogen on N cannot be observed. Only the chemical shifts of the hydrogen on the methylene and methine groups on the main chain can be seen to be between 1 and 2.5.
[0058] The functionalized polyacrylamide was prepared as a 3000 ppm aqueous solution. Separately, a simulated solution was prepared in deionized water containing 5% bentonite, with sodium fluoride added to adjust the fluoride monomer concentration to 600 ppm. The functionalized polyacrylamide solution and the simulated solution were mixed at a 1:2 volume ratio, stirred, and allowed to settle. The supernatant was collected, and the fluoride ion content was tested and recorded in Table 1.
[0059] Example 2
[0060] A functionalized polyacrylamide for alumina production is prepared by copolymerization of acrylamide, polyamine monomer and acrylic acid, and its structural formula is shown in the figure below.
[0061]
[0062] Where a, b, and c are all natural numbers greater than or equal to 1.
[0063] A method for preparing the above-mentioned functionalized polyacrylamide includes the following steps:
[0064] First, prepare monomers with polyamine groups:
[0065] Biguanide and acryloyl chloride were reacted in a mixed solution of acetone and triethylamine at 25°C for 5 hours; wherein the molar ratio of acryloyl chloride to biguanide was 1:1.2 and the mass ratio of acetone to triethylamine was 2:1.
[0066] The reactants are distilled to remove the solvent and excess unreacted monomers to obtain polyamine monomers.
[0067] The reaction mechanism is as follows:
[0068]
[0069] Then weigh out 10 parts acrylamide, 75 parts acrylic acid, 15 parts of the above polyamine monomer, 0.005 parts disodium ethylenediaminetetraacetate, 0.00005 parts potassium persulfate, 0.0007 parts sodium bisulfite and 85 parts deionized water;
[0070] Acrylamide, acrylic acid, polyamine monomer, and disodium ethylenediaminetetraacetate were added to deionized water to prepare a homogeneous solution, and the pH was adjusted to between 6.5 and 7.5 with sodium hydroxide.
[0071] Prepare 1% aqueous solutions of potassium persulfate and sodium bisulfite respectively;
[0072] Cool the resulting mixture to -2 to 0°C, transfer it to an insulated container, and purge with nitrogen for 30 minutes to remove oxygen from the reaction system.
[0073] Potassium persulfate and sodium bisulfite were added to the reaction system in sequence, and nitrogen gas was purged until the system began to heat up. After the heating was completed, the system was kept at the temperature for 2 hours, and the colloidal product was collected.
[0074] The obtained colloid can be pelletized, dried, and pulverized to obtain functionalized polyacrylamide.
[0075] The functionalized polyacrylamide was prepared as a 3000 ppm aqueous solution. Separately, a simulated solution was prepared in deionized water containing 5% bentonite, with sodium fluoride added to adjust the fluoride monomer concentration to 600 ppm. The functionalized polyacrylamide solution and the simulated solution were mixed at a 1:2 volume ratio, stirred, and allowed to settle. The supernatant was collected, and the fluoride ion content was tested and recorded in Table 1.
[0076] Example 3
[0077] A functionalized polyacrylamide for alumina production is prepared by copolymerization of acrylamide, polyamine monomer and acrylic acid, and its structural formula is shown in the figure below.
[0078]
[0079] Where a, b, and c are all natural numbers greater than or equal to 1.
[0080] A method for preparing the above-mentioned functionalized polyacrylamide includes the following steps:
[0081] First, prepare monomers with polyamine groups:
[0082] Tetraethylenepentamine and acryloyl chloride were reacted in a mixed solution of acetone and triethylamine at 25°C for 1 hour; wherein the molar ratio of acryloyl chloride to tetraethylenepentamine was 1:1.2 and the mass ratio of acetone to triethylamine was 2:1.
[0083] The reactants were distilled to remove the solvent and excess unreacted monomers, yielding polyamine monomers.
[0084] The reaction mechanism is as follows:
[0085]
[0086] Then weigh out 12 parts acrylamide, 70 parts acrylic acid, 18 parts of the above polyamine monomer, 0.05 parts disodium ethylenediaminetetraacetate, 0.0003 parts potassium persulfate, 0.0005 parts sodium bisulfite and 75 parts deionized water;
[0087] Acrylamide, acrylic acid, polyamine monomer, and disodium ethylenediaminetetraacetate were added to deionized water to prepare a homogeneous solution, and the pH was adjusted to between 6.5 and 7.5 with sodium hydroxide.
[0088] Prepare 1% aqueous solutions of potassium persulfate and sodium bisulfite respectively;
[0089] Cool the resulting mixture to -2 to 0°C, transfer it to an insulated container, and purge with nitrogen for 30 minutes to remove oxygen from the reaction system.
[0090] Potassium persulfate and sodium bisulfite were added to the reaction system in sequence, and nitrogen gas was purged until the system began to heat up. After the heating was completed, the system was kept at the temperature for 2 hours, and the colloidal product was collected.
[0091] The obtained colloid can be pelletized, dried, and pulverized to obtain functionalized polyacrylamide.
[0092] The proton NMR spectrum of the functionalized polyacrylamide is shown below. Figure 2 As shown, the highest peak is the solvent peak of water. Active hydrogen does not produce a peak in water, so the hydrogen on N cannot be observed. It can be seen that the chemical shifts of hydrogen on the methylene and methine groups on the main chain are between 1 and 2.5, and the chemical shifts of hydrogen on the methylene group in the middle of the polyamine group are between 2.6 and 3.3.
[0093] The functionalized polyacrylamide was prepared as a 3000 ppm aqueous solution. Separately, a simulated solution was prepared in deionized water containing 5% bentonite, with sodium fluoride added to adjust the fluoride monomer concentration to 600 ppm. The functionalized polyacrylamide solution and the simulated solution were mixed at a 1:2 volume ratio, stirred, and allowed to settle. The supernatant was collected, and the fluoride ion content was tested and recorded in Table 1.
[0094] Example 4
[0095] A functionalized polyacrylamide for alumina production is prepared by copolymerization of acrylamide, polyamine monomer and acrylic acid, and its structural formula is shown in the figure below.
[0096]
[0097] Where a, b, and c are all natural numbers greater than or equal to 1.
[0098] A method for preparing the above-mentioned functionalized polyacrylamide includes the following steps:
[0099] First, prepare monomers with polyamine groups:
[0100] Tetraethylenepentamine and acryloyl chloride were reacted in a mixed solution of acetone and triethylamine at 25°C for 1 hour; wherein the molar ratio of acryloyl chloride to tetraethylenepentamine was 1:1.2 and the mass ratio of acetone to triethylamine was 2:1.
[0101] The reactants were distilled to remove the solvent and excess unreacted monomers, yielding polyamine monomers.
[0102] The reaction mechanism is as follows:
[0103]
[0104] Then weigh out 11 parts acrylamide, 64 parts acrylic acid, 25 parts of the above polyamine monomer, 0.03 parts disodium ethylenediaminetetraacetate, 0.0004 parts potassium persulfate, 0.0007 parts sodium bisulfite and 90 parts deionized water;
[0105] Acrylamide, acrylic acid, polyamine monomer, and disodium ethylenediaminetetraacetate were added to deionized water to prepare a homogeneous solution, and the pH was adjusted to between 6.5 and 7.5 with sodium hydroxide.
[0106] Prepare 1% aqueous solutions of potassium persulfate and sodium bisulfite respectively;
[0107] Cool the resulting mixture to -2 to 0°C, transfer it to an insulated container, and purge with nitrogen for 30 minutes to remove oxygen from the reaction system.
[0108] Potassium persulfate and sodium bisulfite were added to the reaction system in sequence, and nitrogen gas was purged until the system began to heat up. After the heating was completed, the system was kept at the temperature for 2 hours, and the colloidal product was collected.
[0109] The obtained colloid can be pelletized, dried, and pulverized to obtain functionalized polyacrylamide.
[0110] The functionalized polyacrylamide was prepared as a 3000 ppm aqueous solution. Separately, a simulated solution was prepared in deionized water containing 5% bentonite, with sodium fluoride added to adjust the fluoride monomer concentration to 600 ppm. The functionalized polyacrylamide solution and the simulated solution were mixed at a 1:2 volume ratio, stirred, and allowed to settle. The supernatant was collected, and the fluoride ion content was tested and recorded in Table 1.
[0111] Comparative Example 1
[0112] This comparative example provides a method for preparing a polymer, comprising the following steps:
[0113] Weigh out 11 parts acrylamide, 64 parts acrylic acid, 0.03 parts disodium ethylenediaminetetraacetate, 0.0004 parts potassium persulfate, 0.0007 parts sodium bisulfite, and 90 parts deionized water;
[0114] Acrylamide, acrylic acid, and disodium EDTA were added to deionized water to prepare a homogeneous solution, and the pH was adjusted to between 6.5 and 7.5 with sodium hydroxide.
[0115] Prepare 1% aqueous solutions of potassium persulfate and sodium bisulfite respectively;
[0116] Cool the resulting mixture to -2 to 0°C, transfer it to an insulated container, and purge with nitrogen for 30 minutes to remove oxygen from the reaction system.
[0117] Potassium persulfate and sodium bisulfite were added to the reaction system in sequence, and nitrogen gas was purged until the system began to heat up. After the heating was completed, the system was kept at the temperature for 2 hours, and the colloidal product was collected.
[0118] The obtained colloid was granulated, dried, and pulverized to obtain the sample of Comparative Example 1.
[0119] The sample from Comparative Example 1 was prepared as a 3000 ppm aqueous solution. Separately, a simulated solution was prepared in deionized water containing 5% bentonite, with sodium fluoride added to adjust the fluoride monomer concentration to 600 ppm. The polymer solution and the simulated solution were mixed at a 1:2 volume ratio, stirred, and allowed to settle. The supernatant was collected, and the fluoride ion content was tested and recorded in Table 1.
[0120] Comparative Example 2
[0121] Commercially available high molecular weight polyacrylamide is sourced from SNF Company of France, model FP6040.
[0122] The above sample was prepared as a 3000 ppm aqueous solution. A 5% bentonite solution was prepared in deionized water, with sodium fluoride added to adjust the fluoride monomer concentration to 600 ppm, thus forming a simulated solution. The polymer solution and the simulated solution were mixed at a 1:2 volume ratio, stirred, and allowed to settle. The supernatant was collected, and the fluoride ion content was tested (see Appendix Table 1).
[0123] The following data demonstrates the superiority of this invention.
[0124] Table 1 lists the performance of the examples and comparative samples, as follows:
[0125] sample Fluoride ion content after treatment (ppm) Example 1 7.9 Example 2 9.1 Example 3 8.4 Example 4 7.1 Comparative Example 1 547 Comparative Example 2 579
[0126] In summary, the polymer obtained by this invention can effectively enrich fluoride ions simultaneously when treating bentonite suspensions containing fluoride ions, reducing the fluoride ion concentration in the treated water to below 10 ppm. When used in alumina processes, it can effectively simplify the process and improve production efficiency.
[0127] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A functionalized polyacrylamide for alumina production, characterized in that, It is obtained by copolymerization of acrylamide structural monomers, anionic structural monomers, and polyamine monomers; the polyamine monomers account for 15% to 25% of the total mass of the polymerization unit; the anionic structural monomers account for 60% to 75% of the total mass of the polymerization unit; the functionalized polyacrylamide has the following structural formula: Where a, b, and c are all natural numbers greater than or equal to 1; R1 is an anionic monomer; and R2 is a polyamine monomer.
2. The functionalized polyacrylamide for alumina production according to claim 1, characterized in that, The R2 mentioned is a side group having one of the following groups:
3. The functionalized polyacrylamide for alumina production according to claim 1 or 2, characterized in that, The anionic monomer is acrylic acid.
4. A method for preparing functionalized polyacrylamide for alumina production, characterized in that, Includes the following steps: Step 1: Material preparation: Weigh 10-15 parts of acrylamide structural monomer, 60-75 parts of anionic structural monomer, 15-25 parts of polyamine monomer, 0.002-0.05 parts of disodium ethylenediaminetetraacetate, 0.00002-0.0005 parts of oxidant, 0.00004-0.0007 parts of reducing agent, and 60-90 parts of deionized water; Step 2: Mixing: Add the acrylamide structural monomer, anionic monomer, polyamine monomer, and disodium ethylenediaminetetraacetate to deionized water according to the above formula to prepare a homogeneous solution. Adjust the pH value to between 6.5 and 7.5 with sodium hydroxide to obtain the mixed solution. Step 3 Deoxygenation: Cool the mixture obtained in Step 2 to -2 to 0℃, transfer it to an insulated container, and purge it with nitrogen for 30 minutes; Step 4 Polymerization: Prepare solutions of the oxidant and reducing agent described in Step 1, add them to the reaction system, purge with nitrogen until the system begins to heat up, and keep warm for 2 hours after the heating is complete; Step 5: Pulverization: The obtained colloid is granulated, dried, and pulverized to obtain the final product.
5. The method for preparing functionalized polyacrylamide for alumina production according to claim 4, characterized in that, The polyamine monomer is synthesized by the following method: Acryloyl chloride and biguanide were dissolved in a mixed solution of acetone and triethylamine and reacted at 25°C for 1–5 hours. The molar ratio of acryloyl chloride to biguanide was 1:1.2, and the mass ratio of acetone to triethylamine was 2:
1. The reactants were distilled to remove the solvent and excess unreacted monomers to obtain polyamine monomers.
6. The method for preparing functionalized polyacrylamide for alumina production according to claim 4, characterized in that, The polyamine monomer is synthesized by the following method: Acryloyl chloride and tetraethylenepentamine were dissolved in a mixed solution of acetone and triethylamine and reacted at 25°C for 1–5 hours. The molar ratio of acryloyl chloride to tetraethylenepentamine was 1:1.2, and the mass ratio of acetone to triethylamine was 2:
1. The reactants were distilled to remove the solvent and excess unreacted monomers to obtain polyamine monomers.
7. A method for preparing functionalized polyacrylamide for alumina production according to any one of claims 4 to 6, characterized in that, The anionic monomer is acrylic acid.
8. The method for preparing functionalized polyacrylamide for alumina production according to claim 7, characterized in that, The oxidant is at least one of potassium bromate, potassium persulfate, and sodium persulfate.
9. The method for preparing functionalized polyacrylamide for alumina production according to claim 7, characterized in that, The reducing agent is at least one of sodium bisulfite, sodium dithionite, and sodium metabisulfite.
10. An application of a functionalized polyacrylamide for alumina production, characterized in that, Based on the functionalized polyacrylamide according to claim 3, when its application concentration is 3000ppm, it can reduce the fluoride content to below 10ppm by treating a fluoride-containing solution containing 600ppm at a volume ratio of 1:1.