Composite treatment agent for domestic sewage and preparation method thereof
By modifying the preparation methods of chelating agents and flocculants, the problem of poor heavy metal chelation and flocculation effects of existing domestic sewage treatment agents has been solved, achieving efficient and stable sewage purification effects, adapting to complex water quality changes, and reducing secondary pollution.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG SHANGXIN ECOLOGICAL CONSTR CO LTD
- Filing Date
- 2026-03-04
- Publication Date
- 2026-05-12
AI Technical Summary
Existing domestic sewage treatment agents have poor selectivity for heavy metal chelation, insufficient chelation stability, high cost, and pose environmental pollution risks. They are also less adaptable to complex water qualities. Traditional inorganic flocculants have slow settling and poor applicability, making it difficult to meet current standards.
By using methods for preparing modified chelating agents and flocculants in modified treatment agents, including the reaction of phytic acid, glycidyl methacrylate, cysteine, sodium alginate, etc., a multifunctional composite treatment agent is formed to achieve the synergistic effect of heavy metal chelation and pollutant flocculation.
It improves the removal rate of heavy metals, rapidly flocculates suspended solids, reduces COD, BOD and suspended solids content, has high treatment efficiency, adapts to different water quality fluctuations, ensures stable effluent quality that meets standards, and reduces secondary pollution.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of wastewater treatment technology, specifically to a composite treatment agent for domestic wastewater and its preparation method. Background Technology
[0002] Domestic sewage refers to wastewater discharged from daily life and public buildings, mainly originating from residences, schools, hospitals, and other places. It includes various types of wastewater such as kitchen washing, bathing, laundry, and toilet flushing. The pollutant composition is complex and fluctuates greatly, mainly containing organic matter, pathogenic microorganisms, nitrogen and phosphorus nutrients, suspended solids, and trace heavy metal ions. Water treatment agents are the core materials for domestic sewage treatment, capable of quickly removing various pollutants from sewage and ensuring effluent meets standards. Traditional single water treatment agents have functional limitations, leading to the rise of composite treatment agents. These agents combine multiple functional components such as heavy metal chelators, flocculants, and adsorbents to achieve complementary advantages, simultaneously removing multiple pollutants such as suspended solids, organic matter, and heavy metals from sewage, meeting current stringent sewage discharge standards. Currently, in terms of heavy metal chelators, existing products suffer from poor selectivity and insufficient chelation stability. Coexisting ions such as calcium and magnesium in domestic sewage easily interfere with the chelation effect, and some chelating agents are costly, difficult to recycle, and prone to secondary pollution. Furthermore, they have weak environmental adaptability in complex water qualities and easily lose chelation activity under extreme pH conditions. Regarding flocculants, traditional inorganic flocculants have slow floc settling and require large amounts, while organic flocculants, although highly efficient, pose a risk of residue. Furthermore, when combined with chelating agents, both can lead to poor synergy and difficulty in controlling the ratio.
[0003] Patent application number 201310731583.0 discloses a domestic sewage treatment agent and its preparation method, using starch xanthate as a heavy metal chelating agent to achieve sewage purification. However, its degradation process may release small amounts of carbon disulfide and sulfides. If the treated sludge is landfilled, the sulfides may seep into groundwater, easily causing secondary pollution. Patent application number 201410156144.6 discloses a composite sewage treatment agent, using polyferric chloride and polyaluminum chloride as flocculants. However, inorganic polymeric flocculants have a single function, focusing only on flocculation and lacking multifunctional synergistic capabilities. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a composite treatment agent for domestic sewage and its preparation method.
[0005] The objective of this invention can be achieved through the following technical solutions: A composite treatment agent for domestic sewage comprises the following raw materials in parts by weight: 15-25 parts ferric chloride, 3-8 parts polyaluminum ferric silicate, 5-8 parts polyacrylamide, 4-8 parts magnesium sulfate, 1-3 parts sodium hydroxide, 15-20 parts modified chelating agent, 20-30 parts modified flocculant, 2-6 parts ferric hydroxide, 15-20 parts bentonite, and 10-15 parts mesoporous silica. The modified chelating agent is prepared by the following steps: Step A1: Mix phytic acid and glycidyl methacrylate, stir at room temperature until the pH value is constant, stop the reaction, and obtain intermediate product 1; Furthermore, the ratio of phytic acid to glycidyl methacrylate is 0.1-0.2 mol: 0.4-0.8 mol; In step A1, phytic acid and glycidyl methacrylate undergo a ring-opening reaction, introducing a double bond into the system and providing reaction conditions for the subsequent thiol-ene click reaction. Phytic acid contains multiple phosphate groups, which can chelate with heavy metal ions such as lead, copper, cadmium, and iron to form insoluble precipitates or stable complexes, thereby removing them from the water. It can also adsorb organic pollutants and suspended particles in the water through electrostatic interactions, improving the clarity of the water.
[0006] Step A2: Mix intermediate product 1, cysteine, triethylamine and tetrahydrofuran, heat to 60°C under nitrogen protection, reflux for 12 h, cool to room temperature, rotary evaporate, wash, centrifuge and vacuum dry to obtain intermediate product 2. Furthermore, the ratio of intermediate 1, cysteine, triethylamine, and tetrahydrofuran is 0.06-0.08 mol: 0.12-0.16 mol: 0.024-0.04 mol: 300-400 mL; In step A2, intermediate 1 and cysteine undergo a thiol-ene click reaction, introducing a carboxyl group into the system and providing reaction conditions for the subsequent esterification reaction. The introduced amino group provides reaction conditions for the subsequent amide grafting reaction.
[0007] Step A3: Mix intermediate product 2, 3-hydroxypropanesulfonic acid, p-toluenesulfonic acid and toluene, stir and heat to 140°C, reflux until no water droplets are formed, add ethyl acetate, wash with 10wt% sodium bicarbonate solution, then wash with deionized water and saturated sodium chloride solution in sequence, separate the liquid, dry, filter, distill under reduced pressure and dry to obtain intermediate product 3. Furthermore, the ratio of the intermediate product 2,3-hydroxypropanesulfonic acid, p-toluenesulfonic acid, toluene, ethyl acetate, sodium bicarbonate solution, deionized water, and saturated sodium chloride solution is 0.033-0.053 mol : 0.06-0.1 mol : 0.006-0.01 mol : 100-140 mL : 120-180 mL : 100-160 mL : 300 mL : 300 mL; In step A3, intermediate product 2 and 3-hydroxypropanesulfonic acid undergo esterification. The introduced sulfonic acid group can form stable complexes with various metal ions in water, reducing ion concentration and enhancing scale inhibition effect.
[0008] Step A4: Mix sodium alginate and deionized water, stir for 1 hour, add EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide) and NHS (N-hydroxysuccinimide), then add intermediate 3, adjust the pH to 4 with 3.6 wt% hydrochloric acid aqueous solution, stir at room temperature for 2 hours, then adjust the pH to 6 with 4 wt% sodium hydroxide aqueous solution, continue the reaction for 1 hour, and finally freeze dry to obtain the modified chelating agent; Furthermore, the ratio of sodium alginate, deionized water, EDC, NHS and intermediate 3 is 1g:100mL:1.4-1.5g:0.8-0.9g:0.01-0.02mol; In step A4, sodium alginate and intermediate product 3 undergo an amide grafting reaction. The sodium alginate molecular chain is rich in active functional groups such as carboxyl and hydroxyl groups, which can undergo complexation reactions with divalent metal ions to form insoluble gel-like precipitates. At the same time, sodium alginate works synergistically with sulfonic acid and phytic acid to efficiently capture heavy metal ions, organic dyes and phosphorus and nitrogen pollutants in water. It has excellent hydrophilicity, good dispersibility, fast treatment rate and no secondary pollution.
[0009] The modified flocculant is prepared by the following steps: Step B1: Mix 1-vinylimidazolium, n-hexane and BHT (2,6-di-tert-butyl-4-methylphenol), purge with nitrogen, add hexadecane bromodrop, heat to 40°C and react for 24 h, cool to room temperature, wash, filter and dry under vacuum to obtain imidazolium bromide; Furthermore, the molar ratio of 1-vinylimidazole, n-hexane, BHT, and hexadecane is 0.1-0.2 mol: 40-50 mL: 0.01-0.02 g: 0.2-0.4 mol; In step B1, 1-vinylimidazolium and hexadecane bromide undergo a quaternization reaction, introducing a double bond into the system and providing reaction conditions for the subsequent polymerization reaction. The resulting quaternary ammonium salt carries a positive charge and can act as a flocculant, neutralizing suspended particles, colloidal substances, and some dye molecules in the water. The resulting flocs are large in volume and settle rapidly, effectively clarifying wastewater.
[0010] Step B2: Mix starch and deionized water, gelatinize at 80°C for 30 min, then cool to 35°C, add imidazole bromide, acrylamide and styrene in sequence, then add Fenton initiator solution, react at 35°C for 1.5 h, then add hydrogen peroxide, and continue to react for 1.5 h. After the reaction is complete, wash with anhydrous ethanol, then wash with 50 wt% ethanol aqueous solution, centrifuge three times, and vacuum dry to obtain modified flocculant; Furthermore, the ratio of starch, deionized water, imidazole bromide, acrylamide, styrene, Fenton initiator solution, hydrogen peroxide, anhydrous ethanol, and ethanol aqueous solution is 10g:80mL:10-20mmol:10-20mmol:5-10mmol:11-22mL:1-2mL:200mL:300mL; Furthermore, the Fenton initiator solution is prepared by mixing hydrogen peroxide, ferrous sulfate and deionized water in a volume ratio of 1-2 mL: 0.335-0.67 g: 10-20 mL; In step B2, starch undergoes a graft copolymerization reaction with imidazole bromide, acrylamide, and styrene. Starch is a natural polymeric flocculant. The introduced amide groups can simultaneously adsorb multiple suspended particles or colloidal particles through hydrogen bonding and electrostatic interactions, forming larger flocs and thus accelerating sedimentation. The imidazole salt increases the molecular weight and charge of starch, giving it bactericidal properties while also increasing its porosity and surface area, enhancing its flocculation ability. The introduced benzene rings and long-chain alkyl groups can enhance the hydrophobic effect of the flocculant, which helps in the formation of flocs and facilitates their separation and sedimentation from water.
[0011] A method for preparing a composite treatment agent for domestic sewage includes the following steps: Step S1: Weigh the raw materials according to the weight parts, add magnesium sulfate, bentonite, mesoporous silica and iron hydroxide into a pulverizer, and pulverize into 110 mesh powder to obtain a mixture; Step S2: Add ferric chloride, polyaluminum ferric silicate and sodium hydroxide to the mixture in sequence, with each raw material added at 3-minute intervals while stirring. Then add modified flocculant, polyacrylamide and modified chelating agent in sequence. After all materials are added, ultrasonically vibrate for 10 minutes with an ultrasonic power of 1000W to obtain a composite treatment agent for domestic sewage.
[0012] The beneficial effects of this invention are: The composite treatment agent for domestic sewage of this invention can be widely applied in the purification and treatment of domestic sewage in residential communities, commercial complexes, and urban sewage treatment plants. When this composite treatment agent is added during the domestic sewage treatment process, the modified chelating agent, through its optimized coordination structure, efficiently chelates free heavy metal ions such as lead, cadmium, and copper in the sewage, forming stable and insoluble chelated precipitates, significantly improving the heavy metal removal rate and preventing secondary pollution caused by the diffusion of heavy metal ions with the effluent. The modified flocculant can quickly adsorb suspended solids, colloidal particles, and dissolved organic matter in the sewage, forming dense and easily settling flocs, significantly accelerating the solid-liquid separation rate and effectively reducing the COD, BOD, and suspended solids content of the sewage. Compared with existing technologies, the composite treatment agent of this invention has the dual functions of heavy metal chelation and pollutant flocculation, resulting in high treatment efficiency, strong adaptability to different water quality fluctuations, and stable effluent quality that meets discharge standards after treatment. It has significant environmental and economic benefits and broad application prospects.
[0013] The modified chelating agent of this invention first utilizes a ring-opening reaction between phytic acid and glycidyl methacrylate. Phytic acid contains multiple phosphate groups, which can chelate with heavy metal ions such as lead, copper, cadmium, and iron to form insoluble precipitates or stable complexes, thereby removing them from water. It can also adsorb organic pollutants and suspended particles in water through electrostatic attraction, improving water clarity. Subsequently, it undergoes a thiol-ene click reaction with cysteine to introduce carboxyl groups into the system. Then, it undergoes an esterification reaction with 3-hydroxypropanesulfonic acid. The introduced sulfonic acid groups can form stable complexes with various metal ions in water, reducing ion concentration and enhancing scale inhibition. Finally, it utilizes sodium alginate for an amide grafting reaction. The sodium alginate molecular chain is rich in active functional groups such as carboxyl and hydroxyl groups, which can complex with divalent metal ions to form insoluble gel-like precipitates. Simultaneously, sodium alginate, sulfonic acid, and phytic acid work synergistically to efficiently capture heavy metal ions, organic dyes, and phosphorus and nitrogen pollutants in water. It exhibits excellent hydrophilicity, good dispersibility, fast treatment rate, and no secondary pollution.
[0014] The modified flocculant of this invention first utilizes a quaternization reaction between 1-vinylimidazolium and hexadecane bromide. The resulting quaternary ammonium salt carries a positive charge and can act as a flocculant to neutralize suspended particles, colloidal substances, and some dye molecules in water. The resulting flocs are large in volume and settle quickly, effectively clarifying wastewater. Then, starch undergoes a graft copolymerization reaction with imidazole bromide, acrylamide, and styrene. Starch is a natural high-molecular-weight flocculant; the introduced amide groups can simultaneously adsorb multiple suspended or colloidal particles through hydrogen bonding and electrostatic interactions, forming larger flocs and accelerating sedimentation. The imidazole salt increases the molecular weight and charge of starch, endowing it with bactericidal properties while increasing its porosity and surface area, enhancing its flocculation ability. The introduced benzene ring and long-chain alkyl groups enhance the hydrophobic effect of the flocculant, contributing to floc formation and facilitating separation and sedimentation from water. Detailed Implementation
[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.
[0016] Example 1: The modified chelating agent was prepared by the following steps: Step A1: Mix phytic acid and glycidyl methacrylate, stir at room temperature until the pH value is constant, stop the reaction, and obtain intermediate product 1. The ratio of phytic acid to glycidyl methacrylate is 0.1 mol: 0.4 mol. Step A2: Mix intermediate product 1, cysteine, triethylamine and tetrahydrofuran, heat to 60°C under nitrogen protection, reflux for 12 h, cool to room temperature, rotary evaporate, wash, centrifuge and vacuum dry to obtain intermediate product 2. The molar ratio of intermediate product 1, cysteine, triethylamine and tetrahydrofuran is 0.06 mol: 0.12 mol: 0.024 mol: 300 mL. Step A3: Mix intermediate product 2,3-hydroxypropanesulfonic acid, p-toluenesulfonic acid, and toluene, stir and heat to 140℃, reflux until no water droplets are formed, add ethyl acetate, wash with 10wt% sodium bicarbonate solution, then wash with deionized water and saturated sodium chloride solution in sequence, separate, dry, filter, distill under reduced pressure and dry to obtain intermediate product 3. The ratio of intermediate product 2,3-hydroxypropanesulfonic acid, p-toluenesulfonic acid, toluene, ethyl acetate, sodium bicarbonate solution, deionized water and saturated sodium chloride solution is 0.033mol:0.06mol:0.006mol:100mL:120mL:100mL:300mL:300mL; Step A4: Mix sodium alginate and deionized water, stir for 1 hour, add EDC and NHS, then add intermediate product 3, adjust the pH to 4 with 3.6 wt% hydrochloric acid aqueous solution, stir at room temperature for 2 hours, then adjust the pH to 6 with 4 wt% sodium hydroxide aqueous solution, continue the reaction for 1 hour, and finally freeze dry to obtain the modified chelating agent. The ratio of sodium alginate, deionized water, EDC, NHS and intermediate product 3 is 1 g: 100 mL: 1.4 g: 0.8 g: 0.01 mol.
[0017] The modified flocculant is prepared by the following steps: Step B1: Mix 1-vinylimidazolium, n-hexane, and BHT, purge with nitrogen, add hexadecane bromodiphenyl ether dropwise, heat to 40°C and react for 24 h, cool to room temperature, wash, filter, and dry under vacuum to obtain imidazolium bromide. The molar ratio of 1-vinylimidazolium, n-hexane, BHT, and hexadecane bromodiphenyl ether is 0.1 mol: 40 mL: 0.01 g: 0.2 mol. Step B2: Mix starch and deionized water, gelatinize at 80℃ for 30 min, then cool to 35℃, add imidazole bromide, acrylamide and styrene in sequence, then add Fenton initiator solution, react at 35℃ for 1.5 h, then add hydrogen peroxide, continue the reaction for 1.5 h, after the reaction is complete, wash with anhydrous ethanol, then wash with 50wt% ethanol aqueous solution, centrifuge three times, and vacuum dry to obtain modified flocculant. The volume ratio of starch, deionized water, imidazole bromide, acrylamide, styrene, Fenton initiator solution, hydrogen peroxide, anhydrous ethanol and ethanol aqueous solution is 10g:80mL:10mmol:10mmol:5mmol:11mL:1mL:200mL:300mL. The Fenton initiator solution is prepared by mixing hydrogen peroxide, ferrous sulfate and deionized water in a volume ratio of 1mL:0.335g:10mL.
[0018] Example 2: The modified chelating agent was prepared by the following steps: Step A1: Mix phytic acid and glycidyl methacrylate, stir at room temperature until the pH value is constant, stop the reaction, and obtain intermediate product 1. The ratio of phytic acid to glycidyl methacrylate is 0.15 mol: 0.6 mol. Step A2: Mix intermediate product 1, cysteine, triethylamine and tetrahydrofuran, heat to 60°C under nitrogen protection, reflux for 12 h, cool to room temperature, rotary evaporate, wash, centrifuge and vacuum dry to obtain intermediate product 2. The molar ratio of intermediate product 1, cysteine, triethylamine and tetrahydrofuran is 0.07 mol: 0.14 mol: 0.032 mol: 350 mL. Step A3: Mix intermediate product 2,3-hydroxypropanesulfonic acid, p-toluenesulfonic acid, and toluene, stir and heat to 140℃, reflux until no water droplets are formed, add ethyl acetate, wash with 10wt% sodium bicarbonate solution, then wash with deionized water and saturated sodium chloride solution in sequence, separate, dry, filter, distill under reduced pressure and dry to obtain intermediate product 3. The ratio of intermediate product 2,3-hydroxypropanesulfonic acid, p-toluenesulfonic acid, toluene, ethyl acetate, sodium bicarbonate solution, deionized water and saturated sodium chloride solution is 0.043mol:0.08mol:0.008mol:120mL:160mL:130mL:300mL:300mL; Step A4: Mix sodium alginate and deionized water, stir for 1 hour, add EDC and NHS, then add intermediate product 3, adjust the pH to 4 with 3.6 wt% hydrochloric acid aqueous solution, stir at room temperature for 2 hours, then adjust the pH to 6 with 4 wt% sodium hydroxide aqueous solution, continue the reaction for 1 hour, and finally freeze dry to obtain the modified chelating agent. The ratio of sodium alginate, deionized water, EDC, NHS and intermediate product 3 is 1 g: 100 mL: 1.45 g: 0.85 g: 0.015 mol.
[0019] The modified flocculant is prepared by the following steps: Step B1: Mix 1-vinylimidazolium, n-hexane, and BHT, purge with nitrogen, add hexadecane bromodiphenyl ether dropwise, heat to 40°C and react for 24 h, cool to room temperature, wash, filter, and dry under vacuum to obtain imidazolium bromide. The molar ratio of 1-vinylimidazolium, n-hexane, BHT, and hexadecane bromodiphenyl ether is 0.15 mol: 45 mL: 0.015 g: 0.3 mol. Step B2: Mix starch and deionized water, gelatinize at 80℃ for 30 min, then cool to 35℃, add imidazole bromide, acrylamide and styrene in sequence, then add Fenton initiator solution, react at 35℃ for 1.5 h, then add hydrogen peroxide, continue the reaction for 1.5 h, after the reaction is complete, wash with anhydrous ethanol, then wash with 50wt% ethanol aqueous solution, centrifuge three times, and vacuum dry to obtain modified flocculant. The volume ratio of starch, deionized water, imidazole bromide, acrylamide, styrene, Fenton initiator solution, hydrogen peroxide, anhydrous ethanol and ethanol aqueous solution is 10g:80mL:15mmol:15mmol:8mmol:16.5mL:1.5mL:200mL:300mL. The Fenton initiator solution is prepared by mixing hydrogen peroxide, ferrous sulfate and deionized water in a volume ratio of 1.5mL:0.5025g:15mL.
[0020] Example 3: The modified chelating agent was prepared by the following steps: Step A1: Mix phytic acid and glycidyl methacrylate, stir at room temperature until the pH value is constant, stop the reaction, and obtain intermediate product 1. The ratio of phytic acid to glycidyl methacrylate is 0.2 mol: 0.8 mol. Step A2: Mix intermediate product 1, cysteine, triethylamine and tetrahydrofuran, heat to 60°C under nitrogen protection, reflux for 12 h, cool to room temperature, rotary evaporate, wash, centrifuge and vacuum dry to obtain intermediate product 2. The molar ratio of intermediate product 1, cysteine, triethylamine and tetrahydrofuran is 0.08 mol 0.16 mol : 0.04 mol : 400 mL. Step A3: Mix intermediate product 2,3-hydroxypropanesulfonic acid, p-toluenesulfonic acid, and toluene, stir and heat to 140℃, reflux until no water droplets are formed, add ethyl acetate, wash with 10wt% sodium bicarbonate solution, then wash with deionized water and saturated sodium chloride solution in sequence, separate, dry, filter, distill under reduced pressure and dry to obtain intermediate product 3. The ratio of intermediate product 2,3-hydroxypropanesulfonic acid, p-toluenesulfonic acid, toluene, ethyl acetate, sodium bicarbonate solution, deionized water and saturated sodium chloride solution is 0.053mol:0.1mol:0.01mol:140mL:180mL:160mL:300mL:300mL; Step A4: Mix sodium alginate and deionized water, stir for 1 hour, add EDC and NHS, then add intermediate product 3, adjust the pH to 4 with 3.6 wt% hydrochloric acid aqueous solution, stir at room temperature for 2 hours, then adjust the pH to 6 with 4 wt% sodium hydroxide aqueous solution, continue the reaction for 1 hour, and finally freeze dry to obtain the modified chelating agent. The ratio of sodium alginate, deionized water, EDC, NHS and intermediate product 3 is 1 g: 100 mL: 1.5 g: 0.9 g: 0.02 mol.
[0021] The modified flocculant is prepared by the following steps: Step B1: Mix 1-vinylimidazolium, n-hexane, and BHT, purge with nitrogen, add hexadecane bromodiphenyl ether dropwise, heat to 40°C and react for 24 h, cool to room temperature, wash, filter, and dry under vacuum to obtain imidazolium bromide. The molar ratio of 1-vinylimidazolium, n-hexane, BHT, and hexadecane bromodiphenyl ether is 0.2 mol: 50 mL: 0.02 g: 0.4 mol. Step B2: Mix starch and deionized water, gelatinize at 80℃ for 30 min, then cool to 35℃, add imidazole bromide, acrylamide and styrene in sequence, then add Fenton initiator solution, react at 35℃ for 1.5 h, then add hydrogen peroxide, continue the reaction for 1.5 h, after the reaction is complete, wash with anhydrous ethanol, then wash with 50wt% ethanol aqueous solution, centrifuge three times, and vacuum dry to obtain modified flocculant. The volume ratio of starch, deionized water, imidazole bromide, acrylamide, styrene, Fenton initiator solution, hydrogen peroxide, anhydrous ethanol and ethanol aqueous solution is 10g:80mL:20mmol:20mmol:10mmol:22mL:2mL:200mL:300mL. The Fenton initiator solution is prepared by mixing hydrogen peroxide, ferrous sulfate and deionized water in a volume ratio of 2mL:0.67g:20mL.
[0022] Example 4: A method for preparing a composite treatment agent for domestic sewage, comprising the following steps: 15 parts of ferric chloride, 3 parts of polyaluminum ferric silicate, 5 parts of polyacrylamide, 4 parts of magnesium sulfate, 1 part of sodium hydroxide, 15 parts of the modified chelating agent prepared in Example 1, 20 parts of the modified flocculant prepared in Example 1, 2 parts of ferric hydroxide, 15 parts of bentonite, and 10 parts of mesoporous silica. Step S1: Weigh the raw materials according to the weight parts, add magnesium sulfate, bentonite, mesoporous silica and iron hydroxide into a pulverizer, and pulverize into 110 mesh powder to obtain a mixture; Step S2: Ferric chloride, polyaluminum ferric silicate, and sodium hydroxide are added to the mixture in sequence, with each raw material added at 3-minute intervals while stirring. Then, the modified flocculant prepared in Example 1, polyacrylamide, and the modified chelating agent prepared in Example 1 are added in sequence. After all materials are added, the mixture is ultrasonically vibrated for 10 minutes at an ultrasonic power of 1000W to obtain a composite treatment agent for domestic sewage.
[0023] Example 5: A method for preparing a composite treatment agent for domestic sewage, comprising the following steps: 20 parts of ferric chloride, 5 parts of polyaluminum ferric silicate, 7 parts of polyacrylamide, 6 parts of magnesium sulfate, 2 parts of sodium hydroxide, 17 parts of the modified chelating agent prepared in Example 2, 25 parts of the modified flocculant prepared in Example 2, 4 parts of ferric hydroxide, 17 parts of bentonite, and 12 parts of mesoporous silica. Step S1: Weigh the raw materials according to the weight parts, add magnesium sulfate, bentonite, mesoporous silica and iron hydroxide into a pulverizer, and pulverize into 110 mesh powder to obtain a mixture; Step S2: Ferric chloride, polyaluminum ferric silicate, and sodium hydroxide are added to the mixture in sequence, with each raw material added at 3-minute intervals while stirring. Then, the modified flocculant prepared in Example 2, polyacrylamide, and the modified chelating agent prepared in Example 2 are added in sequence. After all materials are added, the mixture is ultrasonically vibrated for 10 minutes at an ultrasonic power of 1000W to obtain a composite treatment agent for domestic sewage.
[0024] Example 6: A method for preparing a composite treatment agent for domestic sewage, comprising the following steps: 25 parts of ferric chloride, 8 parts of polyaluminum ferric silicate, 8 parts of polyacrylamide, 8 parts of magnesium sulfate, 3 parts of sodium hydroxide, 20 parts of the modified chelating agent prepared in Example 3, 30 parts of the modified flocculant prepared in Example 3, 6 parts of ferric hydroxide, 20 parts of bentonite, and 15 parts of mesoporous silica. Step S1: Weigh the raw materials according to the weight parts, add magnesium sulfate, bentonite, mesoporous silica and iron hydroxide into a pulverizer, and pulverize into 110 mesh powder to obtain a mixture; Step S2: Ferric chloride, polyaluminum ferric silicate, and sodium hydroxide are added to the mixture in sequence, with each raw material added at 3-minute intervals while stirring. Then, the modified flocculant prepared in Example 3, polyacrylamide, and the modified chelating agent prepared in Example 3 are added in sequence. After all materials are added, the mixture is ultrasonically vibrated for 10 minutes at an ultrasonic power of 1000W to obtain a composite treatment agent for domestic sewage.
[0025] Comparative Example 1: This comparative example is a composite treatment agent. The difference between it and Example 6 is that sodium alginate is used instead of the modified chelating agent prepared in Example 3. All other aspects are the same.
[0026] Comparative Example 2: This comparative example is a composite treatment agent. The difference between it and Example 6 is that starch is used instead of the modified flocculant prepared in Example 3. All other aspects are the same.
[0027] Comparative Example 3: This comparative example is a composite treatment agent. The difference between it and Example 6 is that sodium alginate is used instead of the modified chelating agent prepared in Example 3, and starch is used instead of the modified flocculant prepared in Example 3. All other aspects are the same.
[0028] The performance of the composite treatment agents prepared in Examples 4-6 and Comparative Examples 1-3 was tested: The same domestic sewage source was selected as the test water source, and six equal amounts of domestic sewage were taken from it and numbered 1-6 respectively. Among them, 1-3 used the high-efficiency domestic sewage treatment agent of Examples 4-6 of the present invention, and 4-6 used the composite treatment agent prepared by Comparative Examples 1-3. The water quality after treatment was measured.
[0029] The test results are shown in Table 1: Table 1: Performance Test Results As shown in Table 1, the composite treatment agent prepared according to the present invention significantly reduces the contents of COD, BOD, ammonia nitrogen, total phosphorus, and suspended solids in wastewater after use. The COD removal rate reaches over 95.3%, and the BOD removal rate reaches over 95.1%. Furthermore, the ammonia nitrogen, total phosphorus, and suspended solids levels are all significantly lower than the discharge standards. Data from Comparative Example 1 and Example 6 show that the modified chelating agent prepared according to the present invention can efficiently chelate free lead, cadmium, and copper metal ions in wastewater, significantly improving the heavy metal removal rate. Data from Comparative Example 2 and Example 6 show that the modified flocculant prepared according to the present invention can effectively reduce the COD, BOD, and suspended solids content in wastewater. The raw materials in the composite treatment agent of the present invention promote each other and synergistically enhance each other, achieving highly efficient purification of domestic wastewater.
[0030] The above content is merely an example and illustration of the concept 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 scope defined by the inventive concept, they should all fall within the protection scope of the present invention.
Claims
1. A composite treatment agent for domestic sewage, characterized in that, The raw materials include the following parts by weight: 15-25 parts ferric chloride, 3-8 parts polyaluminum ferric silicate, 5-8 parts polyacrylamide, 4-8 parts magnesium sulfate, 1-3 parts sodium hydroxide, 15-20 parts modified chelating agent, 20-30 parts modified flocculant, 2-6 parts ferric hydroxyoxide, 15-20 parts bentonite, and 10-15 parts mesoporous silica.
2. The composite treatment agent for domestic sewage according to claim 1, characterized in that, The modified chelating agent is prepared by the following steps: Step A1: Mix phytic acid and glycidyl methacrylate, stir at room temperature until the pH value is constant, stop the reaction, and obtain intermediate product 1; Step A2: Mix intermediate product 1, cysteine, triethylamine and tetrahydrofuran, heat to 60°C under nitrogen protection, reflux for 12 h, cool to room temperature, rotary evaporate, wash, centrifuge and vacuum dry to obtain intermediate product 2. Step A3: Mix intermediate product 2, 3-hydroxypropanesulfonic acid, p-toluenesulfonic acid and toluene, stir and heat to 140°C, reflux until no water droplets are formed, add ethyl acetate, wash with 10wt% sodium bicarbonate solution, then wash with deionized water and saturated sodium chloride solution in sequence, separate the liquid, dry, filter, distill under reduced pressure and dry to obtain intermediate product 3. Step A4: Mix sodium alginate and deionized water, stir for 1 hour, add EDC and NHS, then add intermediate product 3, adjust the pH to 4 with 3.6 wt% hydrochloric acid aqueous solution, stir at room temperature for 2 hours, then adjust the pH to 6 with 4 wt% sodium hydroxide aqueous solution, continue the reaction for 1 hour, and finally freeze dry to obtain the modified chelating agent.
3. The composite treatment agent for domestic sewage according to claim 2, characterized in that, In step A1, the ratio of phytic acid to glycidyl methacrylate is 0.1-0.2 mol: 0.4-0.8 mol.
4. The composite treatment agent for domestic sewage according to claim 2, characterized in that, In step A2, the ratio of intermediate product 1, cysteine, triethylamine, and tetrahydrofuran is 0.06-0.08 mol: 0.12-0.16 mol: 0.024-0.04 mol: 300-400 mL.
5. The composite treatment agent for domestic sewage according to claim 2, characterized in that, In step A3, the ratio of the amounts of intermediate product 2,3-hydroxypropanesulfonic acid, p-toluenesulfonic acid, toluene, ethyl acetate, sodium bicarbonate solution, deionized water, and saturated sodium chloride solution is 0.033-0.053 mol : 0.06-0.1 mol : 0.006-0.01 mol : 100-140 mL : 120-180 mL : 100-160 mL : 300 mL : 300 mL.
6. The composite treatment agent for domestic sewage according to claim 2, characterized in that, In step A4, the ratio of sodium alginate, deionized water, EDC, NHS and intermediate product 3 is 1g:100mL:1.4-1.5g:0.8-0.9g:0.01-0.02mol.
7. The composite treatment agent for domestic sewage according to claim 1, characterized in that, The modified flocculant is prepared by the following steps: Step B1: Mix 1-vinylimidazolium, n-hexane and BHT, purge with nitrogen, add hexadecane bromodrop, heat to 40°C and react for 24 h, cool to room temperature, wash, filter and dry under vacuum to obtain imidazolium bromide. Step B2: Mix starch and deionized water, gelatinize at 80°C for 30 min, then cool to 35°C, add imidazole bromide, acrylamide and styrene in sequence, then add Fenton initiator solution, react at 35°C for 1.5 h, then add hydrogen peroxide, and continue the reaction for 1.5 h. After the reaction is complete, wash with anhydrous ethanol, then wash with 50 wt% ethanol aqueous solution, centrifuge three times, and vacuum dry to obtain modified flocculant.
8. The composite treatment agent for domestic sewage according to claim 7, characterized in that, In step B1, the ratio of 1-vinylimidazolium, n-hexane, BHT and hexadecane is 0.1-0.2 mol: 40-50 mL: 0.01-0.02 g: 0.2-0.4 mol.
9. A composite treatment agent for domestic sewage according to claim 7, characterized in that, In step B2, the ratio of starch, deionized water, imidazole bromide, acrylamide, styrene, Fenton initiator solution, hydrogen peroxide, anhydrous ethanol, and ethanol-water solution is 10g:80mL:10-20mmol:10-20mmol:5-10mmol:11-22mL:1-2mL:200mL:300mL. The Fenton initiator solution is composed of hydrogen peroxide, ferrous sulfate, and deionized water in a ratio of 1-2mL: It is prepared by mixing 0.335-0.67g and 10-20mL.
10. A method for preparing a composite treatment agent for domestic sewage according to any one of claims 1-9, characterized in that, The composite treatment agent is prepared by the following steps: Step S1: Weigh the raw materials according to the weight parts, add magnesium sulfate, bentonite, mesoporous silica and iron hydroxide into a pulverizer, and pulverize into 110 mesh powder to obtain a mixture; Step S2: Add ferric chloride, polyaluminum ferric silicate and sodium hydroxide to the mixture in sequence, with each raw material added at 3-minute intervals while stirring. Then add modified flocculant, polyacrylamide and modified chelating agent in sequence. After all materials are added, ultrasonically vibrate for 10 minutes with an ultrasonic power of 1000W to obtain a composite treatment agent for domestic sewage.