Composite metal-based coagulation water purifying agent and preparation method thereof

Abstract

The invention discloses a composite metal-based coagulation water purifying agent and a preparation method thereof, and belongs to the technical field of water treatment.The preparation method comprises the steps that firstly, water dissolution acidification and salting-out are conducted to obtain acidified polyaluminum ferric chloride powder, the acidified polyaluminum ferric chloride powder and cerium nitrate are modified and precipitated to obtain cerium modified polyaluminum ferric chloride powder, then hydrophobization and titanium dioxide grafting are conducted, and the composite metal-based coagulation water purifying agent is obtained. The preparation method comprises the following steps: preparing titanium dioxide grafted composite powder, hydrolyzing nano cellulose to co-deposit silver nitrate and a silane coupling agent so as to obtain antibacterial cellulose, premixing the titanium dioxide grafted composite powder with the antibacterial cellulose and anionic polyacrylamide, adding magnesium aluminum silicate, crushing, carrying out fluidized drying, and spraying a polydimethylsiloxane solution, so as to obtain the antibacterial titanium dioxide composite material. Finally, the composite metal-based coagulation water purifying agent is obtained. Effects of efficient flocculation, photocatalytic antibiosis and the like are achieved, and the method is suitable for advanced treatment of high-difficulty wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a composite metal-based coagulation water purifier and a preparation method thereof. Background Art

[0002] Traditional water purification technologies mainly include sedimentation, filtration and disinfection. Although they can improve water quality, they are limited in removing more complex pollutants such as colloids and dissolved organic matter in water. It is necessary to develop more efficient water purification technologies to cope with the increasingly serious water pollution problem. Coagulation technology is a water treatment method that uses chemical agents to agglomerate tiny particles in water into larger particles, and remove various pollutants in the water through sedimentation or filtration.

[0003] Coagulants are a class of chemical agents that cause colloidal particles in water to aggregate into larger particles, accelerating sedimentation and achieving solid-liquid separation. They are generally categorized as inorganic coagulants and organic polymer coagulants. Inorganic coagulants promote particle aggregation by compressing the colloidal double layer or through adsorption bridging. Organic polymer coagulants, due to their large molecular weight and high charge, can form numerous net-catching structures in water, enhancing the flocculation effect. In practical applications, inorganic and organic polymer coagulants are often used in combination to improve treatment efficiency and reduce costs.

[0004] Composite metal-based coagulation water purifier is a water purifier that combines multiple metal-based components. It aims to improve water treatment effects, reduce production costs, and reduce environmental impacts. This type of water purifier usually contains multiple metal salts and their polymers, such as polyaluminum chloride, ferric chloride, etc. These components play different roles in the water treatment process to achieve more efficient purification effects.

[0005] Chinese invention patent application CN 109678232A discloses a novel polyaluminum chloride water purifier and its preparation method. Aluminum-containing waste residue is completely dissolved in acid, a heavy metal scavenger is added to prepare an aluminum-containing mother liquor, and the resulting mixture is homogenized by high-speed dispersion. An alkaline regulator is then added under high-speed dispersion conditions to adjust the degree of polymerization. The reaction is continued to produce the polyaluminum chloride water purifier. This preparation method utilizes high-speed dispersion technology for homogenizing the aluminum-containing mother liquor and adjusting the degree of polymerization, overcoming the limitations of conventional alkaline regulation systems that limit degree of polymerization.

[0006] However, it can only play a basic coagulation role in low-turbidity wastewater, among which polyaluminum chloride only relies on aluminum hydroxide flocs for adsorption, and has insufficient complexing ability. Its charge neutralization cannot destroy the chromophore group, resulting in low precipitation efficiency and limited wastewater decolorization effect, and it has no antibacterial components. In summary, its effect is average in scenarios such as heavy metal wastewater, high-chroma wastewater, and malodorous water bodies. Summary of the Invention

[0007] The purpose of the present invention is to solve the problem that polyaluminum chloride has insufficient complexing ability during water purification, cannot destroy chromophores, resulting in low precipitation efficiency and limited sewage decolorization effect, and has no antibacterial components, and has general effect in scenarios such as heavy metal wastewater, high chroma sewage, and malodorous water bodies. A composite metal-based coagulation water purifier and a preparation method thereof are provided.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A composite metal-based coagulation water purifier, comprising the following components and raw materials, calculated by mass:

[0010] 75-80 parts of titanium dioxide grafted composite powder, 10-15 parts of antibacterial cellulose, 3-6 parts of anionic polyacrylamide and 2-4 parts of magnesium aluminum silicate;

[0011] Add titanium dioxide grafted composite powder, antibacterial cellulose and anionic polyacrylamide into a high-speed mixer, premix at 300-400 rpm for 10-15 minutes, then add magnesium aluminum silicate and stir for 5-8 minutes to obtain a composite antibacterial flocculant powder;

[0012] The composite antibacterial flocculant powder is added to a jet mill, crushed, transferred to a fluidized bed dryer, and fluidized dried for 1-2 hours under nitrogen. A 0.5wt% polydimethylsiloxane ethanol solution is sprayed and atomized, and fluidization is continued for 20-30 minutes. The material is discharged to obtain a composite metal-based coagulation water purifier.

[0013] Furthermore, the titanium dioxide grafted composite powder is prepared by the following steps:

[0014] Cerium-modified polyaluminium ferric chloride powder, trimethylsilyl chloride and toluene solution are added to a reaction kettle, stirred at 40-50°C for 1-2 hours, filtered, washed with toluene 3-5 times, and vacuum dried to obtain hydrophobized cerium-modified polyaluminium ferric chloride powder; hydrophobized cerium-modified polyaluminium ferric chloride powder, ethylene glycol and n-butyl titanate are added to a reaction kettle, stirred at 400-500 rpm for 6-8 hours, then 98wt% concentrated sulfuric acid and cyclohexanone are added, stirred for 20-30 minutes, reacted at 130-150°C for 8-10 hours, taken out, repeatedly washed with a mixture of isopropyltone and ammonia, and vacuum dried to obtain a titanium dioxide grafted composite powder.

[0015] Furthermore, the amount ratio of cerium-modified polyaluminium ferric chloride powder, trimethylchlorosilane and toluene solution is 75-80 g: 30-40 mL: 160-200 mL;

[0016] The usage ratio of the hydrophobized cerium modified polyaluminum ferric chloride powder, ethylene glycol, n-butyl titanate, concentrated sulfuric acid and cyclohexanone is 75-80 g: 75-80 mL: 0.7-0.8 mL: 2.0-2.4 mL: 100-120 mL.

[0017] Furthermore, the cerium-modified polyaluminium ferric chloride powder is prepared by the following steps:

[0018] Acidified polyaluminium ferric chloride powder, cerium nitrate and deionized water are ultrasonically treated for 20-30 minutes, and then polyethylene glycol is added. The mixture is stirred at 60-80°C for 5-6 hours, and a saturated sodium bicarbonate solution is slowly added dropwise to adjust the pH value to 6. The mixture is reacted at 50-60°C for 2-3 hours, and centrifuged and filtered. The filter cake is washed with deionized water for 3-5 times, freeze-dried, ground, and passed through a 300-mesh sieve to obtain cerium-modified polyaluminium ferric chloride powder.

[0019] Furthermore, the usage ratio of acidified polyaluminum ferric chloride powder, cerium nitrate, deionized water and polyethylene glycol is 75-80 g: 12.0-12.8 g: 1.4-1.6 L: 2.0-2.4 g.

[0020] Furthermore, the acidified polyaluminium ferric chloride powder is prepared by the following steps:

[0021] Add polyaluminium ferric chloride and deionized water into a reactor, stir for 30-40 minutes, slowly add 4 mol / L acetic acid to adjust the pH value to 3.5, react at 70-80°C for 30-40 minutes, then add sodium chloride crystals, stir for 30-40 minutes, cool to 5°C in an ice bath, react for 1-2 hours, crystallize, filter, wash with ethanol 3-5 times, and vacuum dry to constant weight to obtain acidified polyaluminium ferric chloride powder.

[0022] Furthermore, the usage ratio of polyaluminium ferric chloride, deionized water and sodium chloride crystals is 80-84 g:300-330 mL:8.0-8.4 g.

[0023] Furthermore, the antibacterial cellulose is prepared by the following steps:

[0024] Add nanocellulose powder and ultrapure water into a reactor, ultrasonicate for 30-40 minutes, add hexadecyltrimethylammonium bromide and manganese dioxide nanosheets, stir at 30-40°C for 1-2 hours, then add acetic acid, magnetically stir for 30-40 minutes, add tetraethyl silicate, silver nitrate aqueous solution and silane coupling agent KH-550 dropwise, react at 40-50°C for 5-6 hours, wash with ultrapure water and ethanol by centrifugation for 3-5 times, freeze-dry, grind, and pass through a 300-mesh sieve to obtain antibacterial cellulose.

[0025] Furthermore, the dosage ratio of nanocellulose powder, ultrapure water, hexadecyltrimethylammonium bromide, manganese dioxide nanosheets, acetic acid, tetraethyl silicate, silver nitrate aqueous solution and silane coupling agent KH-550 is 14-16 g: 150-200 mL: 1.4-1.6 g: 0.6-0.8 g: 13.8-14.4 mL: 4.0-4.8 g: 0.8-1.2 g: 0.40-0.48 g.

[0026] Furthermore, the preparation method comprises the following steps:

[0027] Step 1: Add titanium dioxide grafted composite powder, antibacterial cellulose and anionic polyacrylamide into a high-speed mixer, premix at 300-400 rpm for 10-15 minutes, then add magnesium aluminum silicate and stir for 5-8 minutes to obtain a composite antibacterial flocculant powder;

[0028] Step 2: Add the composite antibacterial flocculant powder into a jet mill, grind it, transfer it to a fluidized bed dryer, and fluidize and dry it for 1-2 hours under nitrogen. Spray and atomize 0.5wt% polydimethylsiloxane ethanol solution, continue fluidization for 20-30 minutes, and discharge the material to obtain a composite metal-based coagulation water purifier.

[0029] Beneficial effects of the present invention:

[0030] 1. The present invention obtains a composite antibacterial flocculant powder by premixing titanium dioxide grafted composite powder, antibacterial cellulose and anionic polyacrylamide, and then adding magnesium aluminum silicate to obtain the composite antibacterial flocculant powder, which is crushed, fluidized and dried, and sprayed with atomized polydimethylsiloxane ethanol solution to obtain a composite metal-based coagulation water purifier; wherein cerium-modified polyaluminum ferric chloride is used as the core to strengthen coagulation, titanium dioxide grafting imparts photocatalytic self-cleaning ability, antibacterial cellulose inhibits microbial contamination, magnesium aluminum silicate improves stability and hydrophobic treatment, ethylene glycol solvent grafts titanium dioxide, and polymerized aluminum oxide ferric template method is used to prepare a slow-release antibacterial carrier, and air flow crushing and fluidized bed spraying of polydimethylsiloxane are combined to form a moisture-proof coating layer to ensure uniform dispersion and long-term activity of the components, while reducing secondary pollution. It is suitable for deep treatment of complex water bodies and provides a water purifier integrating "coagulation-degradation-antibacterial-antifouling".

[0031] 2. The cerium-modified polyaluminium ferric chloride powder of the present invention significantly improves the coagulation performance and functionality of traditional polyaluminium ferric chloride by introducing rare earth cerium element, strengthens charge neutralization and adsorption bridging effect, catalyzes the formation of dense flocs, increases sedimentation rate, and enhances the removal capacity of heavy metals and organic matter. At the same time, it optimizes the stability of the material structure, can reduce the dosage of the reagent and has no secondary pollution, and provides an efficient, economical and environmentally friendly solution for high-organic matter and high-heavy metal wastewater.

[0032] 3. The titanium dioxide grafted composite powder in the present invention forms a flexible interface layer through surface organic modification and functional grafting of the grafted polymer chains, thereby improving the impact strength and bending strength of the composite material, retaining the photocatalytic activity of titanium dioxide, degrading organic matter, and imparting antibacterial and anti-ultraviolet aging capabilities. Radiation grafting and coupling agents significantly improve dispersibility and eliminate agglomeration.

[0033] 4. The antibacterial cellulose of the present invention has a double synergistic effect of silver-manganese synergistic sterilization and silane coupling, wherein the silver nanoparticles Ag are loaded + It destroys cell membranes and manganese dioxide, produces active oxygen, synergistically inhibits bacteria and blocks biofilm formation, achieving efficient and broad-spectrum antibacterial effects. KH-550 coupling agent enhances interfacial bonding. After multiple washings, the antibacterial effect is still far superior to that of physical adsorption materials. The nanocellulose carrier is biodegradable and is suitable for the simultaneous action of water purifiers and adsorption sterilization. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] Example 1: A composite metal-based coagulation water purifier, comprising the following components in parts by mass:

[0036] 75 parts of titanium dioxide grafted composite powder, 10 parts of antibacterial cellulose, 3 parts of anionic polyacrylamide and 2 parts of magnesium aluminum silicate.

[0037] The preparation method of the composite metal-based coagulation water purifier comprises the following steps:

[0038] Step 1: Add titanium dioxide grafted composite powder, antibacterial cellulose and anionic polyacrylamide into a high-speed mixer, premix at 300 rpm for 10 minutes, then add magnesium aluminum silicate and stir for 5 minutes to obtain a composite antibacterial flocculant powder.

[0039] Step 2: Add the composite antibacterial flocculant powder into a jet mill, crush it, transfer it to a fluidized bed dryer, and fluidize and dry it for 1 hour under nitrogen. Spray and atomize a polydimethylsiloxane ethanol solution with a mass fraction of 0.5%, continue fluidization for 20 minutes, and discharge the material to obtain a composite metal-based coagulation water purifier.

[0040] Through multi-component functional composite and surface hydrophobicity, a water purifier with oxidative degradation, flocculation sedimentation and antibacterial properties is obtained, which is suitable for the deep treatment of difficult-to-degrade organic wastewater and high-bacteria and algae water bodies.

[0041] Specifically, in step 1, the titanium dioxide grafted composite powder is prepared by the following steps:

[0042] 75 g of cerium-modified polyaluminum ferric chloride powder, 30 mL of trimethylsilyl chloride and 160 mL of toluene solution were added to a reactor, stirred at 40° C. for 1 h, filtered, washed with toluene 3 times, and vacuum dried to obtain hydrophobized cerium-modified polyaluminum ferric chloride powder; 75 g of hydrophobized cerium-modified polyaluminum ferric chloride powder, 75 mL of ethylene glycol and 0.7 mL of n-butyl titanate were added to a reactor, stirred at 400 rpm for 6 h, and then 2.0 mL of 98% concentrated sulfuric acid and 100 mL of cyclohexanone were added, stirred for 20 min, reacted at 130° C. for 8 h, taken out, repeatedly washed with a mixture of isopropyltone and ammonia, and vacuum dried to obtain a titanium dioxide grafted composite powder.

[0043] The material is made hydrophobic by a silanization reaction between trimethylchlorosilane and the hydroxyl groups on the surface of cerium-modified polyaluminium ferric chloride, grafting hydrophobic methyl groups. Then, n-butyl titanate is hydrolyzed and condensed under acidic catalysis to generate a titanium dioxide nanolayer in situ on the surface of the hydrophobic material. The titanium dioxide nanolayer has photocatalytic properties, which can improve the ability to degrade organic pollutants and produce a synergistic effect with the flocculation and adsorption of cerium-modified polyaluminium ferric chloride.

[0044] Specifically, the cerium-modified polyaluminium ferric chloride powder is prepared by the following steps:

[0045] 75 g of acidified polyaluminum ferric chloride powder, 12.0 g of cerium nitrate and 1.4 L of deionized water were ultrasonically treated for 20 min, and then 2.0 g of polyethylene glycol was added. The mixture was stirred at 60°C for 5 h, and a saturated sodium bicarbonate solution was slowly added dropwise to adjust the pH value to 6. The mixture was reacted at 50°C for 2 h, and centrifuged and filtered. The filter cake was washed three times with deionized water, freeze-dried, ground, and passed through a 300-mesh sieve to obtain cerium-modified polyaluminum ferric chloride powder.

[0046] The cerium loading is achieved by utilizing the active sites on the surface of acidified polyaluminum ferric chloride and the cerium ions produced by the hydrolysis of cerium nitrate through electrostatic adsorption and coordination bonding. Polyethylene glycol is used as a dispersant to prevent particle agglomeration. Under weak alkaline conditions, sodium bicarbonate is slowly released to promote the stable deposition of cerium hydroxide oxide on the polyaluminum ferric chloride skeleton, forming a cerium-aluminum-iron composite polymer, which improves the flocculation effect and catalytic oxidation function and is suitable for deep treatment of complex water quality.

[0047] Specifically, the acidified polyaluminium ferric chloride powder is prepared by the following steps:

[0048] 80 g of polyaluminium ferric chloride and 300 mL of deionized water were added to a reactor and stirred for 30 min. 4 mol / L acetic acid was slowly added to adjust the pH to 3.5. The mixture was reacted at 70 ° C for 30 min. 8.0 g of sodium chloride crystals were added and stirred for 30 min. The mixture was cooled to 5 ° C in an ice bath and reacted for 1 h. The mixture was crystallized, filtered, washed with ethanol 3 times, and vacuum dried to constant weight to obtain acidified polyaluminium ferric chloride powder.

[0049] Under acidic conditions, the aluminum-iron hydrolysis product forms polyaluminum-ferric chloride sol. The salting-out effect of sodium chloride and low temperature conditions are used to reduce the solubility of the product, promote the precipitation of polyaluminum-ferric chloride crystals from the solution, and finally through ethanol washing and vacuum drying, the purification and high activity of polyaluminum-ferric chloride are achieved.

[0050] Specifically, in step 1, the antibacterial cellulose is prepared by the following steps:

[0051] 14 g of nanocellulose powder and 150 mL of ultrapure water were added to a reactor, ultrasonicated for 30 min, 1.4 g of hexadecyltrimethylammonium bromide and 0.6 g of manganese dioxide nanosheets were added, stirred at 30 ° C for 1 h, and then 13.8 mL of acetic acid was added. The mixture was magnetically stirred for 30 min, 4.0 g of tetraethyl silicate, 0.8 g of silver nitrate aqueous solution and 0.40 g of silane coupling agent KH-550 were added dropwise, and the mixture was reacted at 40 ° C for 5 h. The mixture was centrifuged and washed three times with ultrapure water and ethanol, freeze-dried, ground, and passed through a 300-mesh sieve to obtain antibacterial cellulose.

[0052] The surface of nanocellulose is cationic-modified with hexadecyltrimethylammonium bromide to enhance its binding ability with negatively charged manganese dioxide nanosheets and silver ions. The silane coupling agent KH-550 forms a silanol network after hydrolysis, which cooperates with tetraethyl silicate to generate a silica coating in situ, anchoring manganese oxide and silver ions to the cellulose skeleton. It has high antibacterial activity, structural stability and environmental friendliness.

[0053] Example 2: A composite metal-based coagulation water purifier, comprising the following components in parts by mass:

[0054] 78 parts of titanium dioxide grafted composite powder, 13 parts of antibacterial cellulose, 5 parts of anionic polyacrylamide and 3 parts of magnesium aluminum silicate.

[0055] The preparation method of the composite metal-based coagulation water purifier comprises the following steps:

[0056] Step 1: Add titanium dioxide grafted composite powder, antibacterial cellulose and anionic polyacrylamide into a high-speed mixer, premix at 350 rpm for 13 minutes, then add magnesium aluminum silicate and stir for 7 minutes to obtain a composite antibacterial flocculant powder.

[0057] Step 2: Add the composite antibacterial flocculant powder into a jet mill, crush it, transfer it to a fluidized bed dryer, and fluidize and dry it for 1.5 hours under nitrogen. Spray and atomize a polydimethylsiloxane ethanol solution with a mass fraction of 0.5%, continue fluidization for 25 minutes, and discharge the material to obtain a composite metal-based coagulation water purifier.

[0058] Specifically, in step 1, the titanium dioxide grafted composite powder is prepared by the following steps:

[0059] 78 g of cerium-modified polyaluminum ferric chloride powder, 35 mL of trimethylsilyl chloride and 180 mL of toluene solution were added to a reactor, stirred at 45 ° C for 1.5 hours, filtered, washed with toluene 4 times, and vacuum dried to obtain hydrophobized cerium-modified polyaluminum ferric chloride powder; 78 g of hydrophobized cerium-modified polyaluminum ferric chloride powder, 78 mL of ethylene glycol and 0.75 mL of n-butyl titanate were added to a reactor, stirred at 450 rpm for 7 hours, and then 2.2 mL of 98% concentrated sulfuric acid and 110 mL of cyclohexanone were added, stirred for 25 minutes, reacted at 140 ° C for 9 hours, taken out, repeatedly washed with a mixture of isopropyltone and ammonia, and vacuum dried to obtain a titanium dioxide grafted composite powder.

[0060] Specifically, the cerium-modified polyaluminium ferric chloride powder is prepared by the following steps:

[0061] 78 g of acidified polyaluminum ferric chloride powder, 12.4 g of cerium nitrate and 1.5 L of deionized water were ultrasonically treated for 25 min, and then 2.2 g of polyethylene glycol was added. The mixture was stirred at 70 ° C for 5.5 h, and a saturated sodium bicarbonate solution was slowly added dropwise to adjust the pH value to 6. The mixture was reacted at 55 ° C for 2.5 h, and centrifuged and filtered. The filter cake was washed with deionized water 4 times, freeze-dried, ground, and passed through a 300-mesh sieve to obtain cerium-modified polyaluminum ferric chloride powder.

[0062] Specifically, the acidified polyaluminium ferric chloride powder is prepared by the following steps:

[0063] 82 g of polyaluminium ferric chloride and 315 mL of deionized water were added to a reactor and stirred for 35 min. 4 mol / L acetic acid was slowly added to adjust the pH to 3.5. The mixture was reacted at 75 ° C for 35 min. 8.2 g of sodium chloride crystals were added and stirred for 35 min. The mixture was cooled to 5 ° C in an ice bath and reacted for 1.5 h. The mixture was crystallized, filtered, washed with ethanol 4 times, and vacuum dried to constant weight to obtain acidified polyaluminium ferric chloride powder.

[0064] Specifically, in step 1, the antibacterial cellulose is prepared by the following steps:

[0065] 15 g of nanocellulose powder and 175 mL of ultrapure water were added to a reactor, ultrasonicated for 35 min, 1.5 g of hexadecyltrimethylammonium bromide and 0.7 g of manganese dioxide nanosheets were added, stirred at 35 ° C for 1.5 h, and then 14.1 mL of acetic acid was added. The mixture was magnetically stirred for 35 min, 4.4 g of tetraethyl silicate, 1.0 g of silver nitrate aqueous solution and 0.44 g of silane coupling agent KH-550 were added dropwise, and the mixture was reacted at 45 ° C for 5.5 h. The mixture was centrifuged and washed four times with ultrapure water and ethanol, freeze-dried, ground, and passed through a 300-mesh sieve to obtain antibacterial cellulose.

[0066] Example 3: A composite metal-based coagulation water purifier, comprising the following components and raw materials, calculated by mass:

[0067] 80 parts of titanium dioxide grafted composite powder, 15 parts of antibacterial cellulose, 6 parts of anionic polyacrylamide and 4 parts of magnesium aluminum silicate.

[0068] The preparation method of the composite metal-based coagulation water purifier comprises the following steps:

[0069] Step 1: Add titanium dioxide grafted composite powder, antibacterial cellulose and anionic polyacrylamide into a high-speed mixer, premix at 400 rpm for 15 minutes, then add magnesium aluminum silicate and stir for 8 minutes to obtain a composite antibacterial flocculant powder.

[0070] Step 2: Add the composite antibacterial flocculant powder into a jet mill, crush it, transfer it to a fluidized bed dryer, and fluidize and dry it for 2 hours under nitrogen. Spray and atomize a polydimethylsiloxane ethanol solution with a mass fraction of 0.5%, continue fluidization for 30 minutes, and discharge the material to obtain a composite metal-based coagulation water purifier.

[0071] Specifically, in step 1, the titanium dioxide grafted composite powder is prepared by the following steps:

[0072] 80 g of cerium-modified polyaluminum ferric chloride powder, 40 mL of trimethylsilyl chloride and 200 mL of toluene solution were added to a reactor, stirred at 50° C. for 2 h, filtered, washed with toluene 5 times, and vacuum dried to obtain hydrophobized cerium-modified polyaluminum ferric chloride powder; 80 g of hydrophobized cerium-modified polyaluminum ferric chloride powder, 80 mL of ethylene glycol and 0.8 mL of n-butyl titanate were added to a reactor, stirred at 500 rpm for 8 h, and then 2.4 mL of 98% concentrated sulfuric acid and 120 mL of cyclohexanone were added, stirred for 30 min, reacted at 150° C. for 10 h, taken out, repeatedly washed with a mixture of isopropyltone and ammonia, and vacuum dried to obtain a titanium dioxide grafted composite powder.

[0073] Specifically, the cerium-modified polyaluminium ferric chloride powder is prepared by the following steps:

[0074] 80 g of acidified polyaluminum ferric chloride powder, 12.8 g of cerium nitrate and 1.6 L of deionized water were ultrasonically treated for 30 min, and then 2.4 g of polyethylene glycol was added. The mixture was stirred at 80 ° C for 6 h, and a saturated sodium bicarbonate solution was slowly added dropwise to adjust the pH value to 6. The mixture was reacted at 60 ° C for 3 h, and centrifuged and filtered. The filter cake was washed with deionized water 5 times, freeze-dried, ground, and passed through a 300-mesh sieve to obtain cerium-modified polyaluminum ferric chloride powder.

[0075] Specifically, the acidified polyaluminium ferric chloride powder is prepared by the following steps:

[0076] 84 g of polyaluminium ferric chloride and 330 mL of deionized water were added to a reactor and stirred for 40 min. 4 mol / L acetic acid was slowly added to adjust the pH to 3.5. The mixture was reacted at 80 ° C for 40 min. 8.4 g of sodium chloride crystals were added and stirred for 40 min. The mixture was cooled to 5 ° C in an ice bath and reacted for 2 h. The mixture was crystallized, filtered, washed with ethanol 5 times, and vacuum dried to constant weight to obtain acidified polyaluminium ferric chloride powder.

[0077] Specifically, in step 1, the antibacterial cellulose is prepared by the following steps:

[0078] 16 g of nanocellulose powder and 200 mL of ultrapure water were added to a reactor, ultrasonicated for 40 min, 1.6 g of hexadecyltrimethylammonium bromide and 0.8 g of manganese dioxide nanosheets were added, stirred at 40 ° C for 2 h, and then 14.4 mL of acetic acid was added. The mixture was magnetically stirred for 40 min, 4.8 g of tetraethyl silicate, 1.2 g of silver nitrate aqueous solution and 0.48 g of silane coupling agent KH-550 were added dropwise, and the mixture was reacted at 50 ° C for 6 h. The mixture was centrifuged and washed 5 times with ultrapure water and ethanol, freeze-dried, ground, and passed through a 300-mesh sieve to obtain antibacterial cellulose.

[0079] The anionic polyacrylamide described in Examples 1 to 3 is selected from Gongyi Tenglong Water Treatment Materials Co., Ltd. (cationic polyacrylamide); magnesium aluminum silicate is selected from Lingshou County Bohan Mineral Products Co., Ltd. (Bohan); polydimethylsiloxane is selected from Shandong Huayu Chemical Technology Co., Ltd. (industrial grade); polyaluminum ferric chloride is selected from Henan Liansheng Environmental Protection Technology Co., Ltd. (Liansheng); sodium chloride crystals are selected from Jiangsu Koloji Health Technology Co., Ltd. (Kolondo); nanocellulose is selected from Zibo Daoqin New Materials Co., Ltd. (32); and manganese dioxide nanosheets are selected from Nanjing Jike Biotechnology Co., Ltd. (JK-09).

[0080] Comparative Example 1: The difference from Example 3 is that the step of cerium-modified polyaluminum ferric chloride powder is not performed, and the cerium-modified polyaluminum ferric chloride powder in the step of preparing the titanium dioxide grafted composite powder is replaced by acidified polyaluminum ferric chloride powder, and the other steps remain unchanged to prepare a water purifier.

[0081] Comparative Example 2: The difference from Example 3 is that the step of preparing titanium dioxide grafted composite powder is omitted, the titanium dioxide grafted composite powder in step 1 is replaced by cerium-modified polyaluminum ferric chloride powder, and the other steps remain unchanged to prepare a water purifier.

[0082] Comparative Example 3: The difference from Example 3 is that in the step of preparing the antibacterial cellulose, no silver nitrate aqueous solution is added, and the other steps remain unchanged to prepare the water purifier.

[0083] The water purifiers prepared in Examples 1 to 3 and Comparative Examples 1 to 3 can be added to the sewage to be treated at a concentration of 50-250 mg / L, stirred and mixed thoroughly, and allowed to settle to separate the supernatant and sludge. If necessary, the water purifiers can be exposed to sunlight to activate the photocatalytic function and enhance the water purification effect.

[0084] Water samples were taken from the secondary biochemical outlet of a municipal sewage treatment plant. 150 mg / L of water purifier was added to the sewage to be treated. Coagulation and sedimentation were carried out according to GB / T16881-2008. The supernatant 2 cm above the liquid surface was taken to test the effect of the water purifier in deep treatment. The water quality at the secondary biochemical outlet of the municipal sewage treatment plant was as follows: suspended solids 108 mg / L, ammonia nitrogen 34 mg / L, chemical oxygen demand 162 mg / L, and total phosphorus 3.2 mg / L.

[0085] The chroma removal rate of the water purifier used was tested according to the determination method in GB / T16881-2008, and the ammonia nitrogen removal rate of the water purifier used was tested according to the determination method in HJ 535-2009. The supernatant of the coagulated sewage was filtered with a 0.45μm filter membrane, and the total phosphorus removal rate of the water purifier used was tested according to the determination method in GB 11893-2018 "Water quality - Determination of total phosphorus - Ammonium molybdate spectrophotometry". The chemical oxygen demand removal rate of the water purifier used was tested according to the determination method in HJ 828-2017. The results are shown in Table 1:

[0086] Table 1: Performance test results of composite metal-based coagulation water purifier

[0087]

[0088]

[0089] As can be seen from Table 1, the purification effect of the water purifier prepared in Examples 1 to 3 is significantly better than that in Comparative Examples 1 to 3; it achieves deep purification through the synergistic effect of "flocculation-catalytic oxidation-antibacterial", wherein polyaluminum ferric chloride and polyacrylamide efficiently flocculate and settle suspended matter and colloids, cerium-titanium bimetallic oxide catalyzes the generation of free radicals under light, oxidatively degrades soluble organic matter, silver / manganese modified cellulose provides long-lasting contact bactericidal and algae inhibition capabilities, and the hydrophobic surface and regenerable photocatalytic layer maintain high activity in complex water quality, and are suitable for heavily polluted water bodies such as heavy metal wastewater and high-chroma sewage.

[0090] In Comparative Example 1, the chemical oxygen demand removal rate is significantly reduced, which may be due to the lack of the catalytic oxidation ability of the cerium element. The cerium ions in the cerium-modified polyaluminum ferric chloride can activate the free radical chain reaction through redox reaction, and efficiently mineralize difficult-to-degrade organic matter (such as humus and dye molecules); after replacing it with ordinary acidified polyaluminum ferric chloride, the system loses the oxidative active center and relies only on flocculation to adsorb large molecular colloidal organic matter. The degradation efficiency of small molecular water-soluble pollutants and humus drops sharply, resulting in a decrease in COD removal rate.

[0091] In Comparative Example 2, the chromaticity removal rate and total phosphorus removal rate were significantly reduced, which may be due to the photocatalytic oxidation ability of titanium dioxide, the degradation of organic chromophores to remove chromaticity, the high specific surface area to adsorb phosphates and pigments, and the synergistic enhancement of phosphorus chemical precipitation by the core-shell structure formed with cerium-modified polyaluminum ferric chloride; its single cerium-modified component only retains the basic coagulation function, and cannot achieve the deep mineralization of chromaticity molecules and the efficient adsorption-precipitation conversion of phosphorus, resulting in the simultaneous deterioration of the two indicators.

[0092] In Comparative Example 3, the ammonia nitrogen removal rate was significantly reduced. This may be because the antibacterial effect of silver ions disappeared after silver nitrate was not added, and the water purifier was unable to inhibit the activity of ammonia-forming bacteria, causing nitrogen-containing organic matter to release high concentrations of ammonia nitrogen through microbial decomposition; heterotrophic bacteria multiplied in large numbers to compete for dissolved oxygen, inhibiting nitrifying bacteria from converting ammonia nitrogen into nitrate, and the impact on wastewater with high organic nitrogen content was particularly significant.

[0093] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A composite metal-based coagulation water purifier, characterized in that: Calculated by mass, it includes the following components and raw materials: 75-80 parts of titanium dioxide grafted composite powder, 10-15 parts of antibacterial cellulose, 3-6 parts of anionic polyacrylamide and 2-4 parts of magnesium aluminum silicate; Add titanium dioxide grafted composite powder, antibacterial cellulose and anionic polyacrylamide into a high-speed mixer, premix at 300-400 rpm for 10-15 minutes, then add magnesium aluminum silicate and stir for 5-8 minutes to obtain a composite antibacterial flocculant powder; The composite antibacterial flocculant powder is added to a jet mill, crushed, transferred to a fluidized bed dryer, and fluidized dried for 1-2 hours under nitrogen. 0.5wt% polydimethylsiloxane ethanol solution is sprayed and atomized, and fluidization is continued for 20-30 minutes. The material is discharged to obtain a composite metal-based coagulation water purifier.

2. A composite metal-based coagulation water purifier according to claim 1, characterized in that: The titanium dioxide grafted composite powder is prepared by the following steps: Cerium-modified polyaluminium ferric chloride powder, trimethylsilyl chloride and toluene solution are added to a reactor, stirred at 40-50°C for 1-2 hours, filtered, washed with toluene 3-5 times, and vacuum dried to obtain hydrophobized cerium-modified polyaluminium ferric chloride powder; hydrophobized cerium-modified polyaluminium ferric chloride powder, ethylene glycol and n-butyl titanate are added to a reactor, stirred at 400-500 rpm for 6-8 hours, then 98wt% concentrated sulfuric acid and cyclohexanone are added, stirred for 20-30 minutes, reacted at 130-150°C for 8-10 hours, taken out, repeatedly washed with a mixture of isopropyltone and ammonia, and vacuum dried to obtain a titanium dioxide grafted composite powder.

3. A composite metal-based coagulation water purifier according to claim 2, characterized in that: The dosage ratio of the cerium-modified polyaluminium ferric chloride powder, trimethylchlorosilane and toluene solution is 75-80 g: 30-40 mL: 160-200 mL; The usage ratio of the hydrophobized cerium modified polyaluminum ferric chloride powder, ethylene glycol, n-butyl titanate, concentrated sulfuric acid and cyclohexanone is 75-80 g: 75-80 mL: 0.7-0.8 mL: 2.0-2.4 mL: 100-120 mL.

4. A composite metal-based coagulation water purifier according to claim 3, characterized in that: The cerium-modified polyaluminium ferric chloride powder is prepared by the following steps: Acidified polyaluminium ferric chloride powder, cerium nitrate and deionized water are ultrasonically treated for 20-30 minutes, and then polyethylene glycol is added. The mixture is stirred at 60-80°C for 5-6 hours, and a saturated sodium bicarbonate solution is slowly added dropwise to adjust the pH value to 6. The mixture is reacted at 50-60°C for 2-3 hours, and centrifuged and filtered. The filter cake is washed with deionized water for 3-5 times, freeze-dried, ground, and passed through a 300-mesh sieve to obtain cerium-modified polyaluminium ferric chloride powder.

5. A composite metal-based coagulation water purifier according to claim 4, characterized in that: The usage ratio of the acidified polyaluminium ferric chloride powder, cerium nitrate, deionized water and polyethylene glycol is 75-80 g: 12.0-12.8 g: 1.4-1.6 L: 2.0-2.4 g.

6. A composite metal-based coagulation water purifier according to claim 5, characterized in that: The acidified polyaluminium ferric chloride powder is prepared by the following steps: Add polyaluminium ferric chloride and deionized water into a reactor, stir for 30-40 minutes, slowly add 4 mol / L acetic acid to adjust the pH value to 3.5, react at 70-80°C for 30-40 minutes, then add sodium chloride crystals, stir for 30-40 minutes, cool to 5°C in an ice bath, react for 1-2 hours, crystallize, filter, wash with ethanol 3-5 times, and vacuum dry to constant weight to obtain acidified polyaluminium ferric chloride powder.

7. A composite metal-based coagulation water purifier according to claim 6, characterized in that: The usage ratio of the polyaluminium ferric chloride, deionized water and sodium chloride crystals is 80-84 g:300-330 mL:8.0-8.4 g.

8. A composite metal-based coagulation water purifier according to claim 1, characterized in that: The antibacterial cellulose is prepared by the following steps: Add nanocellulose powder and ultrapure water into a reactor, ultrasonicate for 30-40 minutes, add hexadecyltrimethylammonium bromide and manganese dioxide nanosheets, stir at 30-40°C for 1-2 hours, then add acetic acid, magnetically stir for 30-40 minutes, add tetraethyl silicate, silver nitrate aqueous solution and silane coupling agent KH-550 dropwise, react at 40-50°C for 5-6 hours, wash with ultrapure water and ethanol by centrifugation for 3-5 times, freeze-dry, grind, and pass through a 300-mesh sieve to obtain antibacterial cellulose.

9. A composite metal-based coagulation water purifier according to claim 8, characterized in that: The dosage ratio of the nanocellulose powder, ultrapure water, hexadecyltrimethylammonium bromide, manganese dioxide nanosheets, acetic acid, tetraethyl silicate, silver nitrate aqueous solution and silane coupling agent KH-550 is 14-16 g: 150-200 mL: 1.4-1.6 g: 0.6-0.8 g: 13.8-14.4 mL: 4.0-4.8 g: 0.8-1.2 g: 0.40-0.48 g.

10. The method for preparing a composite metal-based coagulation water purifier according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: Step 1: Add titanium dioxide grafted composite powder, antibacterial cellulose and anionic polyacrylamide into a high-speed mixer, premix at 300-400 rpm for 10-15 minutes, then add magnesium aluminum silicate and stir for 5-8 minutes to obtain a composite antibacterial flocculant powder; Step 2: Add the composite antibacterial flocculant powder into a jet mill, grind it, transfer it to a fluidized bed dryer, and fluidize and dry it for 1-2 hours under nitrogen. Spray and atomize 0.5wt% polydimethylsiloxane ethanol solution, continue fluidization for 20-30 minutes, and discharge the material to obtain a composite metal-based coagulation water purifier.

Images