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

Abstract

The application discloses a composite metal-based coagulation water purifying agent and a preparation method thereof, and belongs to the technical field of water treatment. The acidification and salting-out are firstly carried out on water, and acidified polymeric aluminum ferric chloride powder is obtained. The acidified polymeric aluminum ferric chloride powder is modified and precipitated with cerium nitrate to obtain cerium modified polymeric aluminum ferric chloride powder. The cerium modified polymeric aluminum ferric chloride powder is hydrophobized and grafted with titanium dioxide to obtain titanium dioxide grafted composite powder. In addition, silver nitrate and silane coupling agent are hydrolyzed and co-deposited on nanocellulose to obtain antibacterial cellulose. Finally, the titanium dioxide grafted composite powder is premixed with the antibacterial cellulose and anionic polyacrylamide, and magnesium aluminum silicate is added. Then, the mixture is crushed, fluidized and dried, and a polydimethylsiloxane solution is sprayed, so that the composite metal-based coagulation water purifying agent is finally obtained. The composite metal-based coagulation water purifying agent has the effects of efficient flocculation, photocatalytic antibiosis and the like, and is suitable for deep treatment of high-difficulty wastewater.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water treatment, and specifically relates to a composite metal-based coagulation water purifying agent and a preparation method thereof. BACKGROUND

[0002] Traditional water purification technologies mainly include sedimentation, filtration and disinfection methods, which can improve water quality, but have limited effect on removing complex pollutants such as colloids and dissolved organic matter in water. Therefore, more efficient water purification technologies need to be developed to cope with the increasingly serious water pollution problem. Coagulation technology is a water treatment method that uses chemical agents to make small particles in water coagulate into larger particles, which are then removed by sedimentation or filtration.

[0003] Coagulation water purifying agent refers to a type of chemical agent that can make colloidal particles in water coagulate into larger particles, thereby accelerating sedimentation and achieving solid-liquid separation. It is usually divided into inorganic coagulants and organic polymer coagulants. Inorganic coagulants promote particle coagulation through compression of colloidal double layers or adsorption bridging, while organic polymer coagulants can form a large number of net capture structures in water due to their high molecular weight and charge, thereby enhancing flocculation effect. In practical applications, inorganic coagulants and organic polymer coagulants are often used together to improve treatment efficiency and reduce costs.

[0004] Composite metal-based coagulation water purifying agent is a water purifying agent that combines multiple metal-based components, aiming to improve water treatment efficiency, reduce production costs, and reduce environmental impact. This water purifying agent 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 higher purification efficiency.

[0005] Chinese invention patent application No. CN 109678232A discloses a new type of polyaluminum chloride water purifying agent and its preparation method. The aluminum-containing waste residue is completely dissolved by adding acid, a heavy metal capturing agent is added to prepare an aluminum-containing mother liquor, and a homogenized mother liquor is obtained by high-speed dispersion homogenization. An alkaline adjusting agent is added under high-speed dispersion conditions to adjust the degree of polymerization, and the polyaluminum chloride water purifying agent is obtained by continuous reaction. The preparation method uses high-speed dispersion technology to homogenize the aluminum-containing mother liquor and adjust the degree of polymerization reaction process, overcoming the limitations of traditional alkali adjustment system.

[0006] However, it can only play a basic coagulation role in low-turbidity wastewater, and the polyaluminum chloride relies only on the adsorption of aluminum hydroxide flocs, with insufficient complexing ability. Its charge neutralization cannot destroy the chromophore group, resulting in low precipitation efficiency and limited wastewater decolorization effect. Moreover, it has no antibacterial components. Therefore, its use effect in scenes such as heavy metal-containing wastewater, high-color wastewater and malodorous water bodies is generally poor. SUMMARY

[0007] The present application aims to solve the problem that the complexing capacity of polyaluminum chloride is insufficient when purifying water, which cannot destroy the chromophoric group, resulting in low precipitation efficiency and limited decolorization effect of sewage, and there is no antibacterial component, and the use effect is general in scenes such as heavy metal-containing wastewater, high-color wastewater, and foul-smelling water bodies, and provides a composite metal-based coagulation water purifying agent and a preparation method thereof.

[0008] The object of the present application can be achieved by the following technical solutions:

[0009] A composite metal-based coagulation water purifying agent, by mass fraction, comprises the following component raw materials:

[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] The titanium dioxide grafted composite powder, the antibacterial cellulose, and the anionic polyacrylamide are added to a high-speed mixer, pre-mixed at 300-400 rpm for 10-15 min, then the magnesium aluminum silicate is added, stirred for 5-8 min, to obtain a composite antibacterial flocculant powder;

[0012] The composite antibacterial flocculant powder is added to an air flow crusher, crushed, transferred to a fluidized bed dryer, fluidized and dried under nitrogen for 1-2 h, sprayed with 0.5 wt% polydimethylsiloxane ethanol solution, and continued to be fluidized for 20-30 min, discharged, to obtain a composite metal-based coagulation water purifying agent.

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

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

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

[0016] The amount ratio of hydrophobic 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] Further, the cerium modified polyaluminum ferric chloride powder is prepared by the following steps:

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

[0019] Further, the amount ratio of the 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] Further, the acidified polyaluminum ferric chloride powder is prepared by the following steps:

[0021] Polyaluminum ferric chloride and deionized water are added to a reaction kettle, stirred for 30-40 min, 4 mol / L acetic acid is slowly added to adjust the pH value to 3.5, reacted at 70-80°C for 30-40 min, then sodium chloride crystals are added, stirred for 30-40 min, cooled to 5°C in an ice bath for 1-2 h, crystallized, suction filtered, washed with ethanol for 3-5 times, and vacuum dried to constant weight to obtain the acidified polyaluminum ferric chloride powder.

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

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

[0024] Nanocellulose powder and ultrapure water are added to a reaction kettle, ultrasonically treated for 30-40 min, hexadecyl trimethyl ammonium bromide and manganese dioxide nanosheet are added, stirred at 30-40°C for 1-2 h, then acetic acid is added, magnetically stirred for 30-40 min, tetraethyl orthosilicate, silver nitrate aqueous solution and silane coupling agent KH-550 are added dropwise, reacted at 40-50°C for 5-6 h, washed with ultrapure water and ethanol by centrifugation for 3-5 times, freeze-dried, ground and passed through a 300 mesh sieve to obtain the antibacterial cellulose.

[0025] Further, the dosage ratio of nanocellulose powder, ultrapure water, hexadecyl trimethyl ammonium bromide, manganese dioxide nanosheet, 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] Further, the preparation method comprises the following steps:

[0027] Step one: the titanium dioxide grafted composite powder, antibacterial cellulose and anionic polyacrylamide are added into a high-speed mixer, pre-mixed at 300-400 rpm for 10-15 min, then the magnesium aluminum silicate is added, stirred for 5-8 min, to obtain the composite antibacterial flocculant powder;

[0028] Step two: the composite antibacterial flocculant powder is added into an airflow crusher, crushed, transferred to a fluidized bed dryer, fluidized dried under nitrogen for 1-2 h, sprayed with 0.5 wt% polydimethylsiloxane ethanol solution, continued to be fluidized for 20-30 min, discharged, to obtain a composite metal-based coagulation water purifying agent.

[0029] The beneficial effects of the present application are:

[0030] 1. The present application pre-mixes the titanium dioxide grafted composite powder, antibacterial cellulose and anionic polyacrylamide, then adds the magnesium aluminum silicate, to obtain the composite antibacterial flocculant powder, which is crushed, fluidized dried, and sprayed with polydimethylsiloxane ethanol solution, to obtain a composite metal-based coagulation water purifying agent; wherein the cerium modified polyaluminum ferric chloride is the core of the strengthened coagulation, the titanium dioxide grafting gives the photocatalytic self-cleaning ability, the antibacterial cellulose inhibits microbial pollution, the magnesium aluminum silicate improves the stability and hydrophobic treatment, the titanium dioxide grafted with ethylene glycol solvent, the polyaluminum ferric oxide template method prepares the slow-release antibacterial carrier, and the airflow crushing and the fluidized bed spraying of polydimethylsiloxane form a moisture-proof coating layer, which ensures the uniform dispersion of the components and the long-term activity, reduces the secondary pollution, is suitable for complex water body deep treatment, and provides a water purifying agent integrating "coagulation-degradation-bacteriostasis-pollution resistance".

[0031] 2. The cerium modified polyaluminum ferric chloride powder in the present application significantly improves the coagulation performance and functionality of the traditional polyaluminum ferric chloride by introducing the rare earth cerium element, strengthens the charge neutralization and adsorption bridging effect, catalyzes the generation of dense flocs, improves the settling velocity, enhances the heavy metal and organic matter removal capacity, optimizes the material structure stability, can reduce the reagent dosage and has no secondary pollution, provides an efficient, economical and environmentally friendly solution for high-organic and high-heavy-metal wastewater.

[0032] 3、The titanium dioxide grafting composite powder in the application forms a flexible interface layer through surface organic modification and functional grafting, so that the impact strength and bending strength of the composite material are improved, the photocatalytic activity of titanium dioxide is retained, organic matter can be degraded, and antibacterial and anti-ultraviolet aging abilities are endowed, and the dispersibility is significantly improved through radiation grafting and coupling agent, and agglomeration is eliminated.

[0033] 4、The antibacterial cellulose in the application has silver-manganese synergistic sterilization and silane coupling double synergy, wherein silver nanoparticles Ag + destroy cell membranes and manganese dioxide to produce active oxygen, synergistically inhibit bacteria and block biofilm formation, achieve high-efficiency broad-spectrum antibacterial effect, the KH-550 coupling agent enhances interface bonding, and the antibacterial effect is still much higher than that of physical adsorption type materials after multiple washings, the nanocellulose carrier is biodegradable, and is suitable for water purification agents and adsorption and sterilization synchronous action. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the protection scope of the application.

[0035] Embodiment 1: A composite metal-based coagulation water purification agent, including the following components by mass fraction:

[0036] 75 parts of titanium dioxide grafting 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 purification agent includes the following steps:

[0038] Step one: the titanium dioxide grafting composite powder, the antibacterial cellulose, and the anionic polyacrylamide are added to a high-speed mixer, pre-mixed at 300 rpm for 10 min, then the magnesium aluminum silicate is added, stirred for 5 min, and a composite antibacterial flocculant powder is obtained.

[0039] Step two: the composite antibacterial flocculant powder is added to an airflow crusher, crushed, transferred to a fluidized bed dryer, fluidized and dried under nitrogen for 1 h, a 0.5% polydimethylsiloxane ethanol solution is sprayed and atomized, and the fluidization is continued for 20 min, the material is discharged, and a composite metal-based coagulation water purification agent is obtained.

[0040] Through multi-component functional compounding and surface hydrophobicity, a water purification agent with oxidation degradation, flocculation and sedimentation, and antibacterial performance is obtained, which is suitable for the advanced treatment of refractory organic wastewater and high-bacteria and algae water bodies.

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

[0042] 75 g of cerium modified polymeric aluminum ferric chloride powder, 30 mL of trimethylchlorosilane and 160 mL of toluene solution were added to the reaction kettle, stirred at 40℃ for 1h, filtered, washed with toluene for 3 times, vacuum dried to obtain hydrophobic cerium modified polymeric aluminum ferric chloride powder; 75 g of hydrophobic cerium modified polymeric aluminum ferric chloride powder, 75 mL of ethylene glycol and 0.7 mL of n-butyl titanate were added to the reaction kettle, stirred at 400 rpm for 6h, then 2.0 mL of 98% concentrated sulfuric acid and 100 mL of cyclohexanone were added, stirred for 20 min, reacted at 130℃ for 8h, taken out, repeatedly washed with isopropyl acetone and ammonia mixture, vacuum dried to obtain titanium dioxide grafted composite powder.

[0043] Through silanization reaction of trimethylchlorosilane with hydroxyl groups on the surface of cerium modified polymeric aluminum ferric chloride, hydrophobic methyl groups are grafted to realize material hydrophobicity, and then n-butyl titanate is used to hydrolyze and condense under acidic catalysis to generate titanium dioxide nanolayer in situ on the surface of the hydrophobic material; the titanium dioxide nanolayer has photocatalytic properties and can improve the ability to degrade organic pollutants, and has a synergistic effect with the flocculation and adsorption of cerium modified polymeric aluminum ferric chloride.

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

[0045] 75 g of acidified polymeric aluminum ferric chloride powder, 12.0 g of cerium nitrate and 1.4 L of deionized water were ultrasonically treated for 20 min, then 2.0 g of polyethylene glycol was added, stirred at 60℃ for 5h, slowly added saturated sodium bicarbonate solution to adjust the pH value to 6, reacted at 50℃ for 2h, centrifuged and filtered, the filter cake was washed with deionized water for 3 times, freeze-dried, ground and passed through a 300 mesh sieve to obtain cerium modified polymeric aluminum ferric chloride powder.

[0046] The active sites on the surface of the acidified polymeric aluminum ferric chloride and the cerium ions generated by the hydrolysis of cerium nitrate are loaded by electrostatic adsorption and coordination bonding, and polyethylene glycol is used as a dispersant to prevent particle agglomeration. In weak alkaline conditions, sodium bicarbonate slowly releases to promote the stable deposition of cerium hydroxide on the polymeric aluminum ferric chloride framework to form a cerium-aluminum ferric 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 polymeric aluminum ferric chloride powder is prepared by the following steps:

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

[0049] Under acidic conditions, aluminum-iron hydrolysis products form polymeric ferric chloride sol, and the salting-out effect of sodium chloride and low temperature conditions reduce the solubility of the product, promoting the precipitation of polymeric ferric chloride crystals from the solution. Finally, through ethanol washing and vacuum drying, the purification and high activity of polymeric ferric chloride are realized.

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

[0051] 14g nanocellulose powder and 150mL ultrapure water were added into a reaction kettle, ultrasonicated for 30min, 1.4g cetyltrimethylammonium bromide and 0.6g manganese dioxide nanosheet were added, stirred at 30℃ for 1h, then 13.8mL acetic acid was added, magnetically stirred for 30min, 4.0g tetraethyl orthosilicate, 0.8g silver nitrate aqueous solution and 0.40g silane coupling agent KH-550 were added dropwise, reacted at 40℃ for 5h, washed with ultrapure water and ethanol for 3 times by centrifugation, freeze-dried, ground, and passed through a 300 mesh sieve to obtain antibacterial cellulose.

[0052] The surface of nanocellulose is modified by cetyltrimethylammonium bromide to enhance its binding capacity with negatively charged manganese dioxide nanosheet and silver ions. After the hydrolysis of silane coupling agent KH-550, a silicon hydroxyl network is formed, which cooperates with tetraethyl orthosilicate to generate a silica coating layer 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 purifying agent, by mass fraction, includes the following components:

[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 purifying agent includes the following steps:

[0056] Step one: titanium dioxide grafted composite powder, antibacterial cellulose and anionic polyacrylamide were added into a high-speed mixer, pre-mixed at 350rpm for 13min, then magnesium aluminum silicate was added, stirred for 7min, to obtain a composite antibacterial flocculant powder.

[0057] Step two: the composite antibacterial flocculants powder is added into the jet mill, crushed, transferred to the fluidized bed dryer, dried under nitrogen for 1.5 h, sprayed with 0.5% polydimethylsiloxane ethanol solution, and fluidized for another 25 min. The product is discharged to obtain a composite metal-based coagulation water purifier.

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

[0059] The 78 g cerium modified polyaluminum ferric chloride powder, 35 mL trimethylchlorosilane and 180 mL toluene solution are added into the reaction kettle, stirred at 45℃ for 1.5 h, filtered, washed with toluene 4 times, and vacuum dried to obtain the hydrophobic cerium modified polyaluminum ferric chloride powder; 78 g of the hydrophobic cerium modified polyaluminum ferric chloride powder, 78 mL of ethylene glycol and 0.75 mL of n-butyl titanate are added into the reaction kettle, stirred at 450 rpm for 7 h, then 2.2 mL of 98% concentrated sulfuric acid and 110 mL of cyclohexanone are added, stirred for 25 min, and reacted at 140℃ for 9 h. The product is taken out, repeatedly washed with a mixture of isopropyl alcohol and ammonia, and vacuum dried to obtain the titanium dioxide grafted composite powder.

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

[0061] The 78 g cerium modified polyaluminum ferric chloride powder, 35 mL trimethylchlorosilane and 180 mL toluene solution are added into the reaction kettle, stirred at 45℃ for 1.5 h, filtered, washed with toluene 4 times, and vacuum dried to obtain the hydrophobic cerium modified polyaluminum ferric chloride powder; 78 g of the hydrophobic cerium modified polyaluminum ferric chloride powder, 78 mL of ethylene glycol and 0.75 mL of n-butyl titanate are added into the reaction kettle, stirred at 450 rpm for 7 h, then 2.2 mL of 98% concentrated sulfuric acid and 110 mL of cyclohexanone are added, stirred for 25 min, and reacted at 140℃ for 9 h. The product is taken out, repeatedly washed with a mixture of isopropyl alcohol and ammonia, and vacuum dried to obtain the titanium dioxide grafted composite powder.

[0062] Specifically, the cerium modified polyaluminum ferric chloride powder is prepared by the following steps:

[0063] The 82 g polyaluminum ferric chloride and 315 mL of deionized water are added into the reaction kettle, stirred for 35 min, and then 4 mol / L acetic acid is slowly added to adjust the pH value to 3.5. The mixture is reacted at 75℃ for 35 min, then 8.2 g of sodium chloride crystals are added, stirred for 35 min, cooled to 5℃ in an ice bath for 1.5 h, and crystallized. The product is filtered, washed with ethanol 4 times, and vacuum dried to constant weight to obtain the acidified polyaluminum ferric chloride powder.

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

[0065] Put 15 g of nanocellulose powder and 175 mL of ultrapure water into a reaction kettle, ultrasonic for 35 min, add 1.5 g of hexadecyl trimethyl ammonium bromide and 0.7 g of manganese dioxide nanosheet, stir at 35℃ for 1.5h, then add 14.1 mL of acetic acid, magnetic stirring for 35 min, dropwise add 4.4 g of tetraethyl silicate, 1.0 g of silver nitrate aqueous solution and 0.44 g of silane coupling agent KH-550, react at 45℃ for 5.5h, centrifugal washing with ultrapure water and ethanol for 4 times, freeze-drying, grinding, passing through 300 mesh sieve, to get antibacterial cellulose.

[0066] Example 3: a composite metal-based coagulation water purifying agent, including the following components by mass fraction:

[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 purifying agent includes the following steps:

[0069] Step one: put the titanium dioxide grafted composite powder, antibacterial cellulose and anionic polyacrylamide into a high-speed mixer, pre-mix for 15 min at 400 rpm, then add magnesium aluminum silicate, stir for 8 min, to get a composite antibacterial flocculant powder.

[0070] Step two: put the composite antibacterial flocculant powder into an air flow crusher, crush, transfer to a fluidized bed dryer, fluidized drying under nitrogen for 2h, spray 0.5% polydimethylsiloxane ethanol solution, continue fluidization for 30 min, discharge, to get a composite metal-based coagulation water purifying agent.

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

[0072] Put 80 g of cerium modified polyaluminum ferric chloride powder, 40 mL of trimethylchlorosilane and 200 mL of toluene solution into a reaction kettle, stir at 50℃ for 2h, filter, wash with toluene for 5 times, vacuum drying, to get hydrophobic cerium modified polyaluminum ferric chloride powder; put 80 g of hydrophobic cerium modified polyaluminum ferric chloride powder, 80 mL of ethylene glycol and 0.8 mL of n-butyl titanate into a reaction kettle, stir at 500 rpm for 8h, then add 2.4 mL of 98% concentrated sulfuric acid and 120 mL of cyclohexanone, stir for 30 min, react at 150℃ for 10h, take out, repeatedly clean with isopropyl alcohol and ammonia mixture, vacuum drying, to get titanium dioxide grafted composite powder.

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

[0074] 80 g of acidified polymeric aluminum ferric chloride powder, 12.8 g of cerium nitrate, and 1.6 L of deionized water were ultrasonically treated for 30 min, 2.4 g of polyethylene glycol was then added, and stirring was carried out at 80°C for 6 h. A saturated sodium bicarbonate solution was slowly added dropwise to adjust the pH value to 6, and reaction was carried out at 60°C for 3 h. Centrifugal filtration was carried out, the filter cake was washed with deionized water for 5 times, freeze-drying was carried out, grinding was carried out, and sieving was carried out through a 300-mesh sieve to obtain cerium-modified polymeric aluminum ferric chloride powder.

[0075] Specifically, the acidified polymeric aluminum ferric chloride powder was prepared by the following steps:

[0076] 84 g of polymeric aluminum ferric chloride and 330 mL of deionized water were added into a reaction kettle, stirring was carried out for 40 min, 4 mol / L acetic acid was slowly added to adjust the pH value to 3.5, reaction was carried out at 80°C for 40 min, 8.4 g of sodium chloride crystals were added, stirring was carried out for 40 min, ice bath cooling was carried out to 5°C for 2 h, crystallization was carried out, suction filtration was carried out, washing was carried out with ethanol for 5 times, and vacuum drying was carried out to constant weight to obtain acidified polymeric aluminum ferric chloride powder.

[0077] Specifically, in step one, the antibacterial cellulose was prepared by the following steps:

[0078] 16 g of nanocellulose powder and 200 mL of ultrapure water were added into a reaction kettle, ultrasonic treatment was carried out for 40 min, 1.6 g of hexadecyl trimethyl ammonium bromide and 0.8 g of manganese dioxide nanosheet were added, stirring was carried out at 40°C for 2 h, 14.4 mL of acetic acid was then added, magnetic stirring was carried out for 40 min, 4.8 g of tetraethyl orthosilicate, 1.2 g of silver nitrate aqueous solution, and 0.48 g of silane coupling agent KH-550 were added dropwise, reaction was carried out at 50°C for 6 h, centrifugal washing was carried out with ultrapure water and ethanol for 5 times, freeze-drying was carried out, grinding was carried out, and sieving was carried out through a 300-mesh sieve to obtain antibacterial cellulose.

[0079] The anionic polyacrylamide in Examples 1-3 was selected from Tenglong Water Treatment Material Co., Ltd. (cationic polyacrylamide); the magnesium aluminum silicate was selected from Bohan Mineral Products Co., Ltd. (Bohan); the polydimethylsiloxane was selected from Shandong Huayu Chemical Technology Co., Ltd. (industrial grade); the polymeric aluminum ferric chloride was selected from Henan Liansheng Environmental Protection Technology Co., Ltd. (Liansheng); the sodium chloride crystals were selected from Jiangsu Kolongji Health Technology Co., Ltd. (Kolengdu); the nanocellulose was selected from Zibo Daoqin New Material Co., Ltd. (32); and the manganese dioxide nanosheet was selected from Nanjing Jikeli Biological Technology Co., Ltd. (JK-09).

[0080] Comparative Example 1: The difference from Example 3 is that the step of cerium-modified polymeric aluminum ferric chloride powder is not carried out, and the acidified polymeric aluminum ferric chloride powder is used to replace the cerium-modified polymeric aluminum ferric chloride powder in the step of preparing titanium dioxide grafted composite powder, and the remaining steps remain unchanged to prepare a water purifying agent.

[0081] Comparative Example 2: The difference from Example 3 is that the step of titanium dioxide grafting composite powder is not carried out, and the cerium modified polymeric aluminum ferric chloride powder is used to replace the titanium dioxide grafting composite powder in step one, and the rest of the steps remain unchanged to prepare the water purifying agent.

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

[0083] The water purifying agents prepared in Examples 1-3 and Comparative Examples 1-3 can be added to the wastewater to be treated at 50-250 mg / L, mixed thoroughly, and then allowed to settle, after which the supernatant and sludge are separated. If necessary, the photocatalytic function can be activated by sunlight to enhance the water purification effect.

[0084] The water samples were taken from the effluent of a municipal wastewater treatment plant, and the water purifying agent was added to the wastewater to be treated at 150 mg / L. Coagulation and sedimentation were carried out according to GB / T 16881-2008, and the supernatant was taken from 2 cm above the liquid surface to test the use effect of the water purifying agent in advanced treatment. The effluent of the municipal wastewater 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 color removal rate of the water purifying agent was tested according to the determination method in GB / T 16881-2008, and the ammonia nitrogen removal rate was tested according to the determination method in HJ 535-2009. The supernatant of the coagulated wastewater was filtered with a 0.45 μm filter membrane, and the total phosphorus removal rate of the water purifying agent was tested according to the determination method in GB 11893-2018 "Determination of Total Phosphorus in Water - Ammonium Molybdate Spectrophotometric Method", and the chemical oxygen demand removal rate 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 purifying agent

[0087]

[0088]

[0089] As can be seen from Table 1, the purification effect of the water purifying agent prepared in Examples 1-3 is obviously better than that of Comparative Examples 1-3; it realizes deep purification through the synergistic effect of "flocculation-catalytic oxidation-antibacterial", in which the polyaluminum ferric chloride and polyacrylamide flocculate and settle suspended solids and colloids, the cerium-titanium bimetallic oxide catalyzes the generation of free radicals under light to oxidize and degrade soluble organic matter, the silver / manganese modified cellulose provides long-acting contact sterilization and algal inhibition capacity, the hydrophobic surface and the renewable photocatalytic layer maintain high activity in complex water quality, and it is suitable for heavily polluted water bodies such as wastewater containing heavy metals and high-color wastewater.

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

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

[0092] In Comparative Example 3, the ammonia nitrogen removal rate is significantly reduced, which may be due to the disappearance of silver ion antibacterial effect after not adding silver nitrate, and the water purifying agent cannot inhibit the activity of ammonification bacteria, resulting in the release of high-concentration ammonia nitrogen from the microbial decomposition of nitrogen-containing organic matter; a large number of heterotrophic bacteria reproduce to compete for dissolved oxygen, inhibiting the conversion of ammonia nitrogen to nitrate by nitrifying bacteria, and the effect is particularly significant for wastewater with high organic nitrogen content.

[0093] Although the embodiments of the present application have been shown and described, it can be understood by those of ordinary skill in the art that various changes, modifications, replacements and modifications can be made to these embodiments without departing from the principles and spirits of the present application.

Claims

1. A composite metal-based coagulant water purifier, characterized in that, By weight, the raw materials include the following components: 75-80 parts titanium dioxide grafted composite powder, 10-15 parts antibacterial cellulose, 3-6 parts anionic polyacrylamide and 2-4 parts magnesium aluminum silicate; Add titanium dioxide grafted composite powder, antibacterial cellulose and anionic polyacrylamide to a high-speed mixer and premix at 300-400 rpm for 10-15 min. Then add magnesium aluminum silicate and stir for 5-8 min to obtain composite antibacterial flocculant powder. The composite antibacterial flocculant powder was added to an air jet mill, pulverized, transferred to a fluidized bed dryer, and fluidized and dried under nitrogen for 1-2 hours. A 0.5wt% polydimethylsiloxane ethanol solution was sprayed and atomized, and fluidization was continued for 20-30 minutes. The material was then discharged to obtain a composite metal-based coagulant water purification agent. The titanium dioxide grafted composite powder is prepared by the following steps: Cerium-modified polyaluminum ferric chloride powder, trimethylchlorosilane, and toluene solution were added to a reaction vessel and stirred at 40-50℃ for 1-2 hours. The mixture was then filtered, washed 3-5 times with toluene, and vacuum dried to obtain hydrophobic cerium-modified polyaluminum ferric chloride powder. The hydrophobic cerium-modified polyaluminum ferric chloride powder, ethylene glycol, and n-butyl titanate were added to a reaction vessel and stirred at 400-500 rpm for 6-8 hours. Then, 98wt% concentrated sulfuric acid and cyclohexanone were added, and the mixture was stirred for 20-30 minutes. The reaction was carried out at 130-150℃ for 8-10 hours. The mixture was then removed, repeatedly washed with a mixture of isoacetone and ammonia, and vacuum dried to obtain titanium dioxide grafted composite powder. The cerium-modified polyaluminum ferric chloride powder is prepared by the following steps: Acidified polyaluminum ferric chloride powder, cerium nitrate, and deionized water are ultrasonicated for 20-30 minutes, then polyethylene glycol is added and stirred at 60-80℃ for 5-6 hours. Saturated sodium bicarbonate solution is slowly added dropwise to adjust the pH to 6, and the reaction is carried out at 50-60℃ for 2-3 hours. After centrifugation and filtration, the filter cake is washed with deionized water 3-5 times, freeze-dried, ground, and passed through a 300-mesh sieve to obtain cerium-modified polyaluminum ferric chloride powder. The acidified polyaluminum ferric chloride powder is prepared by the following steps: Polyaluminum ferric chloride and deionized water were added to a reaction vessel and stirred for 30-40 min. 4 mol / L acetic acid was slowly added to adjust the pH to 3.

5. The reaction was carried out at 70-80℃ for 30-40 min. Sodium chloride crystals were then added and stirred for 30-40 min. The mixture was cooled to 5℃ in an ice bath and reacted for 1-2 h. After crystallization, the mixture was filtered, washed 3-5 times with ethanol, and dried under vacuum to constant weight to obtain acidified polyaluminum ferric chloride powder. The antibacterial cellulose is prepared by the following steps: Nanocellulose powder and ultrapure water were added to a reaction vessel and sonicated for 30-40 minutes. Hexadecyltrimethylammonium bromide and manganese dioxide nanosheets were added and stirred at 30-40°C for 1-2 hours. Acetic acid was then added and the mixture was magnetically stirred for 30-40 minutes. Tetraethyl silicate, silver nitrate aqueous solution, and silane coupling agent KH-550 were added dropwise and reacted at 40-50°C for 5-6 hours. The mixture was washed 3-5 times by centrifugation with ultrapure water and ethanol, freeze-dried, ground, and passed through a 300-mesh sieve to obtain antibacterial cellulose.

2. The composite metal-based coagulant water purifier according to claim 1, characterized in that, The ratio of cerium-modified polyaluminum ferric chloride powder, trimethylchlorosilane, and toluene solution is 75-80g: 30-40mL: 160-200mL; The ratio of the hydrophobic cerium-modified polyaluminum ferric chloride powder, ethylene glycol, n-butyl titanate, concentrated sulfuric acid, and cyclohexanone is 75-80g:75-80mL:0.7-0.8mL:2.0-2.4mL:100-120mL.

3. The composite metal-based coagulant water purifier according to claim 1, characterized in that, The ratio of the acidified polyaluminum ferric chloride powder, cerium nitrate, deionized water and polyethylene glycol is 75-80g: 12.0-12.8g: 1.4-1.6L: 2.0-2.4g.

4. The composite metal-based coagulant water purifier according to claim 1, characterized in that, The ratio of the polyaluminum ferric chloride, deionized water, and sodium chloride crystals is 80-84g: 300-330mL: 8.0-8.4g.

5. The composite metal-based coagulant water purifier according to claim 1, characterized in that, The ratio of the following components is as follows: nanocellulose powder, ultrapure water, hexadecyltrimethylammonium bromide, manganese dioxide nanosheets, acetic acid, tetraethyl silicate, silver nitrate aqueous solution, and silane coupling agent KH-550. The ratio is 14-16g: 150-200mL: 1.4-1.6g: 0.6-0.8g: 13.8-14.4mL: 4.0-4.8g: 0.8-1.2g: 0.40-0.48g.

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

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