Polyaluminum ferric sulfate-based composite water purifying agent

Abstract

The application discloses a kind of composite water purifying agent based on polymeric aluminum ferric sulfate.The preparation process is shown as follows: step 1: polymeric aluminum ferric sulfate solution is prepared by reacting ferrous sulfate heptahydrate, aluminum sulfate and sodium chlorate, phosphoric acid, etc.;step 2: the modified polyacrylamide solution is mixed with polymeric aluminum ferric sulfate solution to obtain a composite system;step 3: add the acid ocher soil to the composite system to obtain the composite water purifying agent.The benefits: the modified monomer is prepared by organic synthesis, and is copolymerized with acrylamide and other monomers to obtain modified polyacrylamide;then, the organic polymer is compounded with polymeric aluminum ferric sulfate solution and acid ocher soil to build a ternary water purification system of "inorganic-organic-mineral";the composite water purifying agent has the efficient electric neutralization capacity of inorganic flocculants, the bridging flocculation of organic polymers and the adsorption performance of minerals, and shows excellent flocculation and sedimentation effect and pollutant removal capacity.

Description

Technical Field

[0001] This invention belongs to the field of water purification agent technology, specifically, it relates to a composite water purification agent based on polyaluminum ferric sulfate. Background Technology

[0002] With rapid industrialization and urbanization, water pollution has become increasingly serious, especially the presence of colloidal particles, organic matter, and heavy metal pollutants in water bodies, posing a severe threat to the ecological environment and human health. Currently, water purification agents are widely used in the water treatment field, with inorganic flocculants (such as polyaluminum sulfate and polyferric sulfate) becoming the mainstream choice due to their high charge neutralization capacity and cost advantages. However, traditional inorganic water purification agents have significant drawbacks: firstly, the flocs they form are small and loose, with slow settling speeds, resulting in low treatment efficiency; secondly, their removal effect on dissolved organic matter and heavy metals is limited, making it difficult to meet the high-standard treatment requirements of complex water qualities. Furthermore, when dealing with water bodies with high turbidity or high pollution loads, single inorganic water purification agents often require excessive dosage, which not only increases treatment costs but may also introduce secondary pollution.

[0003] While organic polymeric flocculants (such as polyacrylamide) can improve floc structure through bridging, their single charge characteristic limits their charge neutralization capacity, and they are not effective at adsorbing hydrophobic organic matter and heavy metals. Although mineral materials (such as activated carbon and bentonite) have adsorption properties, they have poor dispersibility when used alone and are difficult to effectively synergize with other components.

[0004] Therefore, in order to solve the above problems, the present invention provides a composite water purification agent based on polyaluminum ferric sulfate. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a composite water purification agent based on polyaluminum ferric sulfate.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A preparation process for a composite water purification agent based on polyaluminum ferric sulfate is as follows:

[0008] Step 1: Mix ferrous sulfate heptahydrate with deionized water, adjust the pH to 0.5-1, add sodium chlorate, and stir for 30-40 minutes to obtain a ferrous sulfate mixture; add aluminum sulfate to deionized water, stir evenly, mix with the ferrous sulfate mixture and phosphoric acid, raise the temperature to 80-90℃, stir for 30-40 minutes, add sodium carbonate, and continue stirring for 30-40 minutes to obtain a polyaluminum ferric sulfate solution;

[0009] Step 2: Add the modified polyacrylamide to deionized water to obtain a modified polyacrylamide solution; then slowly add it dropwise to a polyaluminum ferric sulfate solution, raise the temperature to 60-70℃, and react for 2-3 hours to obtain a composite system;

[0010] Step 3: Add acidic ochre clay to the composite system, maintain 60-70℃, adjust the pH value to 4-5, and stir for 3-4 hours to obtain the composite water purification agent.

[0011] In this process, ferrous sulfate heptahydrate is oxidized with sodium chlorate under acidic conditions, converting some ferrous ions into ferric ions. Simultaneously, aluminum sulfate dissolves and mixes with the ferric ions. Phosphoric acid is added as a stabilizer to promote the hydrolytic polymerization of ferric and aluminum ions at high temperature, forming a polynuclear hydroxyl-bridged structure. Subsequently, sodium carbonate is added to adjust the pH value, further promoting hydroxyl-bridged polymerization, ultimately generating a stable polyaluminum ferric sulfate solution.

[0012] In the compounding stage of the composite water purification agent, modified polyacrylamide solution is slowly added dropwise to polyaluminum ferric sulfate solution, allowing the inorganic flocculant to combine with the organic polymer. The long-chain structure of modified polyacrylamide can bridge the polyaluminum ferric sulfate colloid, forming a larger flocculation network, while its cationic groups enhance the charge neutralization capacity. Subsequently, acidic ochre clay is added, whose surface iron ions can react with the anionic groups (-COO-) of modified polyacrylamide. - Coordination is achieved to obtain an "inorganic-organic-mineral" composite water purification system.

[0013] More preferably, the ferrous sulfate mixture raw material includes the following components: by weight, 15-18 parts ferrous sulfate heptahydrate, 30-35 parts deionized water, and 1.2-1.5 parts sodium chlorate;

[0014] The raw materials for the polyaluminum ferric sulfate solution include the following components by weight: 12-14 parts aluminum sulfate, 30-45 parts deionized water, 0.3-0.5 parts phosphoric acid, 45-55 parts ferrous sulfate mixture, and 1.8-2.2 parts sodium carbonate.

[0015] In a more optimized manner, the raw materials of the composite system include the following components: by weight, 0.1-0.2 parts modified polyacrylamide, 10-12 parts deionized water, and 60-70 parts polyaluminum ferric sulfate solution.

[0016] In a more optimized manner, the raw materials of the composite water purification agent include the following components: 5-8 parts by weight of acidic ochre clay and 60-80 parts by weight of the composite system.

[0017] The modified polyacrylamide is prepared in a more optimized manner as follows:

[0018] S1: Add dehydrorosin acid to anhydrous dichloromethane, cool to 0°C in an ice bath, slowly add oxaloyl chloride and N,N-dimethylformamide, keep the temperature below 5°C throughout the process, remove the ice bath, stir at room temperature for 1-2 hours, remove the solvent by rotary evaporation to obtain dehydrorosin acyl chloride;

[0019] S2: Add dehydroabiyl chloride to tetrahydrofuran, cool to 0°C in an ice bath, and slowly add 3-bromopropanol and triethylamine dropwise in sequence, keeping the temperature below 10°C. React at room temperature for 6-8 hours. After the reaction is complete, filter to remove triethylamine hydrochloride, concentrate the filtrate under reduced pressure, and purify by column chromatography to obtain propyl bromide dehydroabiyl chloride.

[0020] S3: Under a protective atmosphere, propyl bromide dehydrorosinate, N-vinylimidazole and methanol are mixed, the temperature is raised to 60-70℃, and the mixture is refluxed for 12-15 hours. After the reaction is completed, the mixture is cooled to room temperature, filtered, washed and dried to obtain the modified monomer.

[0021] S4: Dissolve the modified monomer in ethanol to obtain a modified monomer solution; under a protective atmosphere, add acrylamide, methacryloyloxyethyltrimethylammonium chloride, the modified monomer solution, and acrylic acid sequentially to deionized water, stir until completely dissolved, adjust the pH to 5-6, add ammonium persulfate dropwise, raise the temperature to 50-60℃, react for 3-4 hours, then add hydroquinone, stir for 10-15 minutes, filter, wash, and dry to obtain modified polyacrylamide.

[0022] In this scheme, dehydrorosin acid and oxaloyl chloride undergo an acylation reaction under the catalysis of N,N-dimethylformamide to generate the more reactive dehydrorosinyl chloride. The specific reaction process is shown below:

[0023]

[0024] In this process, dehydrorosinyl chloride and 3-bromopropanol are esterified in the presence of triethylamine (an acid-binding agent) to generate ester compounds with bromine-terminated groups (introducing active sites for subsequent reactions). The specific reaction process is shown below:

[0025]

[0026] In this scheme, the brominated ester reacts with N-vinylimidazole via a nucleophilic substitution reaction (SN2), where the bromine atom is replaced by an imidazole group to form a modified monomer, the structure of which is shown below:

[0027]

[0028] In this scheme, the modified monomer is copolymerized with acrylamide (AM), methacryloyloxyethyltrimethylammonium chloride (DMC), and acrylic acid (AA), and free radical polymerization is initiated by ammonium persulfate to generate amphoteric (anionic / cationic) modified polyacrylamide.

[0029] More preferably, the dehydrorosinyl chloride raw material comprises the following components: by weight, 50-55 parts dehydrorosin acid, 250-300 parts anhydrous dichloromethane, 30-35 parts oxaloyl chloride, and 1-2 parts N,N-dimethylformamide.

[0030] More preferably, the brominated dehydrorosinyl ester raw material comprises the following components: by weight, 50-55 parts dehydrorosinyl chloride, 200-250 parts tetrahydrofuran, 25-30 parts 3-bromopropanol, and 20-25 parts triethylamine.

[0031] More preferably, the modified monomer raw material comprises the following components: 50-55 parts by weight of propyl bromide dehydrorosinate, 15-20 parts by weight of N-vinylimidazole, and 150-200 parts by weight of methanol.

[0032] In a more optimized manner, the modified polyacrylamide raw material comprises the following components: by weight, 5-10 parts of modified monomer, 50-80 parts of ethanol, 60-70 parts of acrylamide, 20-30 parts of methacryloyloxyethyltrimethylammonium chloride, 1-5 parts of acrylic acid, 500-600 parts of deionized water, 0.05-0.1 parts of ammonium persulfate, and 0.1-0.2 parts of hydroquinone.

[0033] In a more optimized manner, the preparation process of the acidic ochre clay is as follows: ochre clay is crushed to 200 mesh, stirred and reacted with 10-15% sulfuric acid at 80-90℃ for 2-3 hours, filtered, washed with deionized water until neutral, and dried at 105℃ to obtain acidic ochre clay; the mass ratio of ochre clay to sulfuric acid is 1:3.

[0034] The beneficial effects of this invention are:

[0035] This invention prepares modified monomers through organic synthesis and copolymerizes them with monomers such as acrylamide to obtain modified polyacrylamide. Subsequently, this organic polymer is compounded with polyaluminum ferric sulfate solution and acidic ochre clay to construct an "inorganic-organic-mineral" ternary water purification system. This composite water purification agent combines the efficient charge neutralization capacity of inorganic flocculants, the bridging flocculation effect of organic polymers, and the adsorption properties of minerals, exhibiting excellent flocculation and sedimentation effects and pollutant removal capabilities. Details are as follows:

[0036] Firstly, the modified polyacrylamide prepared in this scheme is an amphoteric organic polymer that can form a synergistic effect with the positively charged polynuclear hydroxyl complex generated by the hydrolysis of polyaluminum ferric sulfate. This dual positively charged system can more effectively neutralize negatively charged colloidal particles and organic matter in water, significantly reducing the zeta potential of the colloidal system and making the destabilization process more thorough. Simultaneously, the anionic groups (COO-) of the modified polyacrylamide... -It can also react with Fe on the surface of acidic ochre soil. 3+ Coordination occurs, tightly binding the three components into a unified network structure;

[0037] Secondly, the long molecular chains of modified polyacrylamide act as bridges, with one end linked to the hydroxyl complex of polyaluminum ferric sulfate via coordination bonds, and the other end connected to ochre particles via electrostatic interactions. This special connection method allows the inorganic flocculant and mineral materials to be uniformly dispersed in the organic polymer network, forming a composite floc with a three-dimensional structure. Compared with single components, this composite floc is not only larger and denser, but also contains a porous skeleton provided by ochre, giving it both good settling performance and sufficient porosity to adsorb and retain pollutants.

[0038] Thirdly, polyaluminum ferric sulfate is mainly used for the removal of colloidal particles and some heavy metals, while modified polyacrylamide is good at capturing dissolved organic matter, and acidic ochre clay provides additional adsorption sites and catalytic active sites. Among them, the hydrophobic dehydroabrasive acid segments of modified polyacrylamide can adsorb hydrophobic organic matter, and the imidazole groups can also capture polar pollutants through coordination, further improving the water purification effect. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1: A preparation process for a composite water purification agent based on polyaluminum ferric sulfate is as follows:

[0041] Step 1: Mix 15 parts of ferrous sulfate heptahydrate with 30 parts of deionized water, adjust the pH to 0.5, add 1.2 parts of sodium chlorate, and stir for 30 minutes to obtain a ferrous sulfate mixture; add 12 parts of aluminum sulfate to 30 parts of deionized water, stir evenly, mix with 45 parts of the ferrous sulfate mixture and 0.3 parts of phosphoric acid, raise the temperature to 80℃, stir for 30 minutes, add 1.8 parts of sodium carbonate, and continue stirring for 30 minutes to obtain a polyaluminum ferric sulfate solution;

[0042] Step 2: Add 0.1 parts of modified polyacrylamide to 10 parts of deionized water to obtain a modified polyacrylamide solution; then slowly add it dropwise to 60 parts of polyaluminum ferric sulfate solution, raise the temperature to 60℃, and react for 2 hours to obtain a composite system;

[0043] Step 3: Add 5 parts of acidic ochre clay to 60 parts of the composite system, maintain 60℃, adjust the pH value to 4, stir for 3 hours to obtain the composite water purification agent;

[0044] The preparation process of acidic ochre clay is as follows: ochre clay is crushed to 200 mesh, stirred and reacted with 10% sulfuric acid at 80°C for 2 hours, filtered, washed with deionized water until neutral, and dried at 105°C to obtain acidic ochre clay; the mass ratio of ochre clay to sulfuric acid is 1:3.

[0045] The preparation process of modified polyacrylamide is as follows:

[0046] S1: Add 50 parts of dehydrorosin acid to 250 parts of anhydrous dichloromethane, cool to 0°C in an ice bath, slowly add 30 parts of oxaloyl chloride and 1 part of N,N-dimethylformamide, keep the temperature below 5°C throughout the process, remove the ice bath, stir at room temperature for 1 hour, remove the solvent by rotary evaporation to obtain dehydrorosin yl chloride.

[0047] S2: Add 50 parts of dehydrorosinyl chloride to 200 parts of tetrahydrofuran, cool to 0°C in an ice bath, and slowly add 25 parts of 3-bromopropanol and 20 parts of triethylamine dropwise, keeping the temperature below 10°C, and react at room temperature for 6 hours. After the reaction is complete, filter to remove triethylamine hydrochloride, concentrate the filtrate under reduced pressure, and purify by column chromatography to obtain propyl bromide dehydrorosinyl chloride.

[0048] S3: Under a protective atmosphere, 50 parts of propyl bromide dehydrorosinate, 15 parts of N-vinylimidazole and 150 parts of methanol were mixed, the temperature was raised to 60°C and refluxed for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain the modified monomer.

[0049] S4: Dissolve 5 parts of the modified monomer in 50 parts of ethanol to obtain a modified monomer solution; under a protective atmosphere, add 60 parts of acrylamide, 20 parts of methacryloyloxyethyltrimethylammonium chloride, the modified monomer solution, and 1 part of acrylic acid to 500 parts of deionized water in sequence, stir until completely dissolved, adjust the pH to 5, add 0.05 parts of ammonium persulfate dropwise, raise the temperature to 50°C, react for 3 hours, then add 0.1 parts of hydroquinone, stir for 10 minutes, filter, wash, and dry to obtain modified polyacrylamide.

[0050] Example 2: A preparation process for a composite water purification agent based on polyaluminum ferric sulfate is as follows:

[0051] Step 1: Mix 18 parts of ferrous sulfate heptahydrate with 35 parts of deionized water, adjust the pH to 1, add 1.5 parts of sodium chlorate, and stir for 40 minutes to obtain a ferrous sulfate mixture; add 14 parts of aluminum sulfate to 45 parts of deionized water, stir evenly, mix with 55 parts of the ferrous sulfate mixture and 0.5 parts of phosphoric acid, raise the temperature to 90℃, stir for 40 minutes, add 2.2 parts of sodium carbonate, and continue stirring for 40 minutes to obtain a polyaluminum ferric sulfate solution;

[0052] Step 2: Add 0.2 parts of modified polyacrylamide to 12 parts of deionized water to obtain a modified polyacrylamide solution; then slowly add it dropwise to 70 parts of polyaluminum ferric sulfate solution, raise the temperature to 70℃, and react for 3 hours to obtain a composite system;

[0053] Step 3: Add 8 parts of acidic ochre clay to 80 parts of the composite system, maintain 70℃, adjust the pH value to 5, stir for 4 hours to obtain the composite water purification agent;

[0054] The preparation process of acidic ochre clay is as follows: ochre clay is crushed to 200 mesh, stirred and reacted with 10% sulfuric acid at 80°C for 2 hours, filtered, washed with deionized water until neutral, and dried at 105°C to obtain acidic ochre clay; the mass ratio of ochre clay to sulfuric acid is 1:3.

[0055] The preparation process of modified polyacrylamide is as follows:

[0056] S1: Add 55 parts of dehydrorosin acid to 300 parts of anhydrous dichloromethane, cool to 0°C in an ice bath, slowly add 35 parts of oxaloyl chloride and 2 parts of N,N-dimethylformamide, keep the temperature below 5°C throughout the process, remove the ice bath, stir at room temperature for 2 hours, remove the solvent by rotary evaporation to obtain dehydrorosin acyl chloride.

[0057] S2: Add 55 parts of dehydrorosinyl chloride to 250 parts of tetrahydrofuran, cool to 0°C in an ice bath, and slowly add 30 parts of 3-bromopropanol and 25 parts of triethylamine dropwise, keeping the temperature below 10°C, and react at room temperature for 8 hours. After the reaction is complete, filter to remove triethylamine hydrochloride, concentrate the filtrate under reduced pressure, and purify by column chromatography to obtain propyl brominated dehydrorosinyl chloride.

[0058] S3: Under a protective atmosphere, 55 parts of propyl bromide dehydrorosinate, 20 parts of N-vinylimidazole and 200 parts of methanol were mixed, the temperature was raised to 70°C and refluxed for 15 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain the modified monomer.

[0059] S4: Dissolve 10 parts of the modified monomer in 80 parts of ethanol to obtain a modified monomer solution; under a protective atmosphere, add 70 parts of acrylamide, 30 parts of methacryloyloxyethyltrimethylammonium chloride, the modified monomer solution, and 5 parts of acrylic acid sequentially to 600 parts of deionized water, stir until completely dissolved, adjust the pH to 6, add 0.1 parts of ammonium persulfate dropwise, raise the temperature to 60℃, react for 4 hours, then add 0.2 parts of hydroquinone, stir for 15 minutes, filter, wash, and dry to obtain modified polyacrylamide.

[0060] Example 3: A preparation process for a composite water purification agent based on polyaluminum ferric sulfate is as follows:

[0061] Step 1: Mix 16.5 parts of ferrous sulfate heptahydrate with 32.5 parts of deionized water, adjust the pH to 0.75, add 1.35 parts of sodium chlorate, and stir for 35 minutes to obtain a ferrous sulfate mixture; add 13 parts of aluminum sulfate to 37.5 parts of deionized water, stir evenly, mix with 50 parts of the ferrous sulfate mixture and 0.4 parts of phosphoric acid, raise the temperature to 85°C, stir for 35 minutes, add 2.0 parts of sodium carbonate, and continue stirring for 35 minutes to obtain a polyaluminum ferric sulfate solution;

[0062] Step 2: Add 0.15 parts of modified polyacrylamide to 11 parts of deionized water to obtain a modified polyacrylamide solution; then slowly add it dropwise to 65 parts of polyaluminum ferric sulfate solution, raise the temperature to 65℃, and react for 2.5 h to obtain a composite system;

[0063] Step 3: Add 6.5 parts of acidic ochre clay to 70 parts of the composite system, maintain 65℃, adjust the pH value to 4.5, stir for 3.5 hours to obtain the composite water purification agent;

[0064] The preparation process of acidic ochre clay is as follows: ochre clay is crushed to 200 mesh, stirred and reacted with 10% sulfuric acid at 80°C for 2 hours, filtered, washed with deionized water until neutral, and dried at 105°C to obtain acidic ochre clay; the mass ratio of ochre clay to sulfuric acid is 1:3.

[0065] The preparation process of modified polyacrylamide is as follows:

[0066] S1: Add 52.5 parts of dehydrorosin acid to 275 parts of anhydrous dichloromethane, cool to 0°C in an ice bath, slowly add 32.5 parts of oxaloyl chloride and 1.5 parts of N,N-dimethylformamide, keep the temperature below 5°C throughout the process, remove the ice bath, stir at room temperature for 1.5 h, remove the solvent by rotary evaporation to obtain dehydrorosin acyl chloride;

[0067] S2: 52.5 parts of dehydrorosinyl chloride were added to 225 parts of tetrahydrofuran, cooled to 0°C in an ice bath, and 27.5 parts of 3-bromopropanol and 22.5 parts of triethylamine were slowly added dropwise in sequence, keeping the temperature below 10°C. The reaction was carried out at room temperature for 7 hours. After the reaction was completed, the triethylamine hydrochloride was removed by filtration, the filtrate was concentrated under reduced pressure, and purified by column chromatography to obtain propyl bromide dehydrorosinyl chloride.

[0068] S3: Under a protective atmosphere, 52.5 parts of propyl bromide dehydrorosinate, 17.5 parts of N-vinylimidazole and 175 parts of methanol were mixed, the temperature was raised to 65°C, and the mixture was refluxed for 13.5 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed and dried to obtain the modified monomer.

[0069] S4: Dissolve 7.5 parts of the modified monomer in 65 parts of ethanol to obtain a modified monomer solution; under a protective atmosphere, add 65 parts of acrylamide, 25 parts of methacryloyloxyethyltrimethylammonium chloride, the modified monomer solution, and 3 parts of acrylic acid sequentially to 550 parts of deionized water, stir until completely dissolved, adjust the pH to 5.5, add 0.075 parts of ammonium persulfate dropwise, raise the temperature to 55℃, react for 3.5 h, then add 0.15 parts of hydroquinone, stir for 12.5 min, filter, wash, and dry to obtain modified polyacrylamide.

[0070] Comparative Example 1: Using a single polyaluminum ferric sulfate water purifier, as detailed below:

[0071] Mix 16.5 parts of ferrous sulfate heptahydrate with 32.5 parts of deionized water, adjust the pH to 0.75, add 1.35 parts of sodium chlorate, and stir for 35 minutes to obtain a ferrous sulfate mixture. Add 13 parts of aluminum sulfate to 37.5 parts of deionized water, stir evenly, mix with 50 parts of the ferrous sulfate mixture and 0.4 parts of phosphoric acid, raise the temperature to 85°C, stir for 35 minutes, add 2.0 parts of sodium carbonate, and continue stirring for 35 minutes to obtain polyaluminum ferric sulfate water purification agent.

[0072] Comparative Example 2: Unmodified polyacrylamide was used instead of modified polyacrylamide, and the rest was the same as in Example 3, as follows:

[0073] Step 1: Mix 16.5 parts of ferrous sulfate heptahydrate with 32.5 parts of deionized water, adjust the pH to 0.75, add 1.35 parts of sodium chlorate, and stir for 35 minutes to obtain a ferrous sulfate mixture; add 13 parts of aluminum sulfate to 37.5 parts of deionized water, stir evenly, mix with 50 parts of the ferrous sulfate mixture and 0.4 parts of phosphoric acid, raise the temperature to 85°C, stir for 35 minutes, add 2.0 parts of sodium carbonate, and continue stirring for 35 minutes to obtain a polyaluminum ferric sulfate solution;

[0074] Step 2: Add 0.15 parts of polyacrylamide to 11 parts of deionized water to obtain a modified polyacrylamide solution; then slowly add it dropwise to 65 parts of polyaluminum ferric sulfate solution, raise the temperature to 65℃, and react for 2.5 h to obtain a composite system;

[0075] Step 3: Add 6.5 parts of acidic ochre clay to 70 parts of the composite system, maintain 65℃, adjust the pH value to 4.5, stir for 3.5 hours to obtain the composite water purification agent;

[0076] The preparation process of acidic ochre clay is as follows: ochre clay is crushed to 200 mesh, stirred and reacted with 10% sulfuric acid at 80°C for 2 hours, filtered, washed with deionized water until neutral, and dried at 105°C to obtain acidic ochre clay; the mass ratio of ochre clay to sulfuric acid is 1:3.

[0077] The preparation process of polyacrylamide is as follows:

[0078] Under a protective atmosphere, 65 parts of acrylamide, 25 parts of methacryloyloxyethyltrimethylammonium chloride, and 3 parts of acrylic acid were added sequentially to 550 parts of deionized water and stirred until completely dissolved. The pH was adjusted to 5.5, and 0.075 parts of ammonium persulfate were added dropwise. The temperature was raised to 55°C and the reaction was carried out for 3.5 hours. Then, 0.15 parts of hydroquinone were added, and the mixture was stirred for 12.5 minutes. The mixture was filtered, washed, and dried to obtain modified polyacrylamide.

[0079] Comparative Example 3: No modified polyacrylamide was added; all other aspects were the same as in Example 3, as detailed below:

[0080] Step 1: Mix 16.5 parts of ferrous sulfate heptahydrate with 32.5 parts of deionized water, adjust the pH to 0.75, add 1.35 parts of sodium chlorate, and stir for 35 minutes to obtain a ferrous sulfate mixture; add 13 parts of aluminum sulfate to 37.5 parts of deionized water, stir evenly, mix with 50 parts of the ferrous sulfate mixture and 0.4 parts of phosphoric acid, raise the temperature to 85°C, stir for 35 minutes, add 2.0 parts of sodium carbonate, and continue stirring for 35 minutes to obtain a polyaluminum ferric sulfate solution;

[0081] Step 2: Add 6.5 parts of acidic ochre clay to 70 parts of polyaluminum ferric sulfate solution, maintain 65℃, adjust the pH to 4.5, stir for 3.5h to obtain composite water purification agent;

[0082] The preparation process of acidic ochre clay is as follows: ochre clay is crushed to 200 mesh, stirred and reacted with 10% sulfuric acid at 80°C for 2 hours, filtered, washed with deionized water until neutral, and dried at 105°C to obtain acidic ochre clay; the mass ratio of ochre clay to sulfuric acid is 1:3.

[0083] Detection experiment: Kaolin was dissolved in deionized water to prepare a suspension with a turbidity of 100 NTU. Humic acid (20 mg / L) was added to simulate COD pollution. Pb(NO3)2 and K2Cr2O7 solutions were added to increase the turbidity of Pb. 2+ Cr 6+ The concentration of each sample was 10 mg / L to obtain simulated wastewater. 500 mL of the simulated wastewater was placed in a beaker, the pH was adjusted to 7, and 50 mg / L of the composite water purification agent obtained in the examples and comparative examples was added. The mixture was stirred, and the following experiments were conducted:

[0084] (1) Take the supernatant and measure the absorbance at a wavelength of 550 nm using a spectrophotometer. Convert the absorbance to NTU and calculate the turbidity removal rate.

[0085] (2) The COD removal rate was determined by the potassium dichromate method (GB11914-89);

[0086] (3) After filtering the supernatant, the residual Pb was detected using an atomic absorption spectrophotometer. 2+ Pb was calculated 2+ Removal rate;

[0087] (4) Record the settlement time; the obtained data is shown in the table below:

[0088]

[0089] Table 1

[0090] Conclusion: The composite water purification agent obtained in the examples achieves efficient and rapid water purification through the synergistic effect of the three components. Its comprehensive performance far exceeds that of single or binary components, and it is suitable for treating complex wastewater (containing turbidity, organic matter and heavy metal pollution).

[0091] Comparative Example 1 relied solely on inorganic flocculants, lacking the bridging effect of organic polymers, resulting in small flocs and slow settling (15 min), leading to low removal rates of organic matter (COD) and heavy metals (≤70%) due to the absence of ochre adsorption assistance. Comparative Example 2, with the bridging effect of ordinary polyacrylamide, improved the turbidity removal rate (90.1%), but lacked amphoteric charges and hydrophobic groups, limiting its removal of COD and heavy metals. Comparative Example 3, with ochre adsorption, improved Pb removal. 2+ The removal rate was 82.3%, but the lack of a bridging network of polyacrylamide resulted in loose flocs (settling time 12 min).

[0092] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0093] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A composite water purification agent based on polyaluminum ferric sulfate, characterized in that: The preparation process of the composite water purification agent is as follows: Step 1: Mix ferrous sulfate heptahydrate with deionized water, adjust the pH to 0.5-1, add sodium chlorate, and stir for 30-40 minutes to obtain a ferrous sulfate mixture; add aluminum sulfate to deionized water, stir evenly, mix with the ferrous sulfate mixture and phosphoric acid, raise the temperature to 80-90℃, stir for 30-40 minutes, add sodium carbonate, and continue stirring for 30-40 minutes to obtain a polyaluminum ferric sulfate solution; Step 2: Add the modified polyacrylamide to deionized water to obtain a modified polyacrylamide solution; then slowly add it dropwise to a polyaluminum ferric sulfate solution, raise the temperature to 60-70℃, and react for 2-3 hours to obtain a composite system; Step 3: Add acidic ochre clay to the composite system, maintain 60-70℃, adjust the pH value to 4-5, stir for 3-4 hours to obtain the composite water purification agent; The preparation process of the modified polyacrylamide is as follows: S1: Add dehydrorosin acid to anhydrous dichloromethane, cool to 0°C in an ice bath, slowly add oxaloyl chloride and N,N-dimethylformamide, keep the temperature below 5°C throughout the process, remove the ice bath, stir at room temperature for 1-2 hours, remove the solvent by rotary evaporation to obtain dehydrorosin acyl chloride; S2: Add dehydroabiyl chloride to tetrahydrofuran, cool to 0°C in an ice bath, and slowly add 3-bromopropanol and triethylamine dropwise in sequence, keeping the temperature below 10°C. React at room temperature for 6-8 hours. After the reaction is complete, filter to remove triethylamine hydrochloride, concentrate the filtrate under reduced pressure, and purify by column chromatography to obtain propyl bromide dehydroabiyl chloride. S3: Under a protective atmosphere, propyl bromide dehydrorosinate, N-vinylimidazole and methanol are mixed, the temperature is raised to 60-70℃, and the mixture is refluxed for 12-15 hours. After the reaction is completed, the mixture is cooled to room temperature, filtered, washed and dried to obtain the modified monomer. S4: Dissolve the modified monomer in ethanol to obtain a modified monomer solution; under a protective atmosphere, add acrylamide, methacryloyloxyethyltrimethylammonium chloride, the modified monomer solution, and acrylic acid sequentially to deionized water, stir until completely dissolved, adjust the pH to 5-6, add ammonium persulfate dropwise, raise the temperature to 50-60℃, react for 3-4 hours, then add hydroquinone, stir for 10-15 minutes, filter, wash, and dry to obtain modified polyacrylamide.

2. The composite water purification agent based on polyaluminum ferric sulfate according to claim 1, characterized in that: The raw materials for the ferrous sulfate mixture include the following components: by weight, 15-18 parts ferrous sulfate heptahydrate, 30-35 parts deionized water, and 1.2-1.5 parts sodium chlorate; The raw materials for the polyaluminum ferric sulfate solution include the following components by weight: 12-14 parts aluminum sulfate, 30-45 parts deionized water, 0.3-0.5 parts phosphoric acid, 45-55 parts ferrous sulfate mixture, and 1.8-2.2 parts sodium carbonate.

3. The composite water purification agent based on polyaluminum ferric sulfate according to claim 1, characterized in that: The raw materials of the composite system include the following components: by weight, 0.1-0.2 parts modified polyacrylamide, 10-12 parts deionized water, and 60-70 parts polyaluminum ferric sulfate solution.

4. The composite water purification agent based on polyaluminum ferric sulfate according to claim 1, characterized in that: The raw materials of the composite water purification agent include the following components: by weight, 5-8 parts acidic ochre clay and 60-80 parts composite system.

5. The composite water purification agent based on polyaluminum ferric sulfate according to claim 1, characterized in that: The dehydrorosin acyl chloride raw material comprises the following components: by weight, 50-55 parts dehydrorosin acid, 250-300 parts anhydrous dichloromethane, 30-35 parts oxaloyl chloride, and 1-2 parts N,N-dimethylformamide.

6. The composite water purification agent based on polyaluminum ferric sulfate according to claim 1, characterized in that: The brominated dehydrorosin propyl ester raw material comprises the following components: by weight, 50-55 parts dehydrorosin acyl chloride, 200-250 parts tetrahydrofuran, 25-30 parts 3-bromopropanol, and 20-25 parts triethylamine.

7. The composite water purification agent based on polyaluminum ferric sulfate according to claim 1, characterized in that: The modified monomer raw material includes the following components: by weight, 50-55 parts of propyl bromide dehydrorosinate, 15-20 parts of N-vinylimidazole, and 150-200 parts of methanol.

8. The composite water purification agent based on polyaluminum ferric sulfate according to claim 1, characterized in that: The modified polyacrylamide raw material comprises the following components by weight: 5-10 parts modified monomer, 50-80 parts ethanol, 60-70 parts acrylamide, 20-30 parts methacryloyloxyethyltrimethylammonium chloride, 1-5 parts acrylic acid, 500-600 parts deionized water, 0.05-0.1 parts ammonium persulfate, and 0.1-0.2 parts hydroquinone.

9. A composite water purification agent based on polyaluminum ferric sulfate according to claim 1, characterized in that: The preparation process of the acidic ochre clay is as follows: ochre clay is crushed to 200 mesh, stirred and reacted with 10-15% sulfuric acid at 80-90℃ for 2-3 hours, filtered, washed with deionized water until neutral, and dried at 105℃ to obtain acidic ochre clay; the mass ratio of ochre clay to sulfuric acid is 1:3.

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