Recyclable water treatment agent based on polyaluminum chloride and preparation method thereof

Abstract

The invention relates to a recyclable water treatment agent based on polyaluminum chloride and a preparation method thereof, and belongs to the technical field of sewage treatment. According to the recyclable water treatment agent, hollow porous magnetic ferroferric oxide serves as a carrier, di-n-butylamine and 3-chloropropyltrimethoxysilane are used for substitution to prepare a surface treatment agent, the surface treatment agent is loaded to the surface of the carrier through the coupling effect, a tertiary amine structure in molecules of the surface treatment agent is coordinated with aluminum chloride, and the recyclable water treatment agent is prepared under the alkaline hot reflux condition. Polyaluminum chloride is formed on the surface in situ, a quaternary ammonium structure is formed by bromoethanol and tertiary amine in the polymerization process, the hollow porous carrier has good suspension dispersion capacity in sewage, and the surface quaternary ammonium structure and polyaluminum chloride form a charge neutralization-flocculation dual mechanism, so that efficient and deep purification is realized; meanwhile, quick separation and recovery can be achieved through an external magnetic field, and efficient recovery of polyaluminum chloride is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and in particular, relates to a recyclable water treatment agent based on polyaluminium chloride and a preparation method thereof. Background Art

[0002] Polyaluminium chloride (PAC), as a traditional inorganic polymer flocculant, is widely used due to its low cost and wide applicability, but it has problems such as slow sedimentation rate, difficulty in recovery and easy residue.

[0003] In recent years, magnetic water treatment agents have become a research hotspot due to their ability to be quickly separated and recovered through an external magnetic field. In the existing technology, PAC is often loaded on the surface of a magnetic carrier (such as ferroferric oxide) to improve its recyclability. However, this type of technology still has the following problems: traditional magnetic carriers are mostly solid or dense structures, resulting in poor suspension of the material in sewage, limited contact area with pollutants, affecting flocculation efficiency, high manufacturing costs of ultrafine carriers (such as nanomaterials), and difficult to recycle and separate; PAC and magnetic carriers are mostly combined through physical adsorption, and are easily detached due to hydraulic scouring or pH changes, resulting in reduced reusability; this seriously restricts the development of recyclable water treatment agents. Summary of the invention

[0004] In order to solve the technical problems mentioned in the background technology, the purpose of the present invention is to provide a recyclable water treatment agent based on polyaluminium chloride and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a recyclable water treatment agent based on polyaluminium chloride specifically comprises the following steps:

[0007] Step S1: premix di-n-butylamine, 3-chloropropyltrimethoxysilane and anhydrous toluene in a dry atmosphere, add potassium hydroxide and mix, heat to 80-100° C. and stir to react for 1.6-2.2 hours, filter after cooling, and then evaporate toluene under reduced pressure to obtain a surface treatment agent;

[0008] Step S2: premixing the surface treatment agent and ethanol aqueous solution, adjusting the pH value to 4 with acetic acid and stirring for hydrolysis for 1-1.5 hours, adding the magnetic carrier and ultrasonically dispersing, stirring for coupling for 12 hours, filtering and washing the filter cake to obtain a modified carrier;

[0009] Step S3: dissolve aluminum chloride hexahydrate, bromoethanol and methanol, add the modified carrier, stir and disperse, heat to 60-70° C. and reflux, slowly add sodium hydroxide aqueous solution and stir to react for 6-8 hours, cool, filter and dry to obtain a recyclable water treatment agent.

[0010] In the above step S1, the feed ratio of di-n-butylamine, 3-chloropropyltrimethoxysilane, potassium hydroxide and anhydrous toluene is 0.1 mol: 0.1 mol: 2.5-4 g: 70-100 mL, and 3-chloropropyltrimethoxysilane reacts with di-n-butylamine to form a tertiary amine compound.

[0011] In the above step S2, the feed ratio of the magnetic carrier, the surface treatment agent and the ethanol aqueous solution is 50g:3.6-4.8g:130-180mL, the volume fraction of the ethanol aqueous solution is 30-40%, and the surface treatment agent is hydrolyzed in the acidic ethanol aqueous solution and then coupled with the magnetic carrier for loading.

[0012] In the above step S3, the feed ratio of the modified carrier, aluminum chloride hexahydrate, sodium hydroxide, bromoethanol and methanol is 10g:8.5-10.2g:2.6-3.3g:20-25mL:150-200mL, the mass fraction of the sodium hydroxide aqueous solution is 8-10%, the tertiary amine organic structure grafted on the surface of the modified carrier forms a coordination effect with aluminum chloride, and aluminum chloride is enriched near the surface of the modified carrier. Under the condition of hot reflux, sodium hydroxide promotes the in-situ polymerization loading of aluminum chloride on the surface of the modified carrier, and at the same time, promotes bromoethanol to quaternize the tertiary amine structure to form a quaternary ammonium positive charge on the surface of the composite structure.

[0013] The magnetic carrier is prepared by the following steps:

[0014] Step A1: dissolving ferric chloride hexahydrate, ferrous sulfate heptahydrate and polyvinyl pyrrolidone in deionized water, adding polystyrene microspheres and stirring to disperse, adjusting the pH value of the dispersion to 10 with ammonia water, pressurizing the reaction system to 2-3 bar, heating to 120-130° C. and reacting for 4.5-6 hours, cooling and filtering, and drying the filter cake at 200° C. to obtain a composite precursor;

[0015] Step A2: immerse the composite precursor in dichloromethane, stir for 24 hours, dissolve and remove the polystyrene microspheres, filter and dry to obtain a magnetic carrier.

[0016] In the above step A1, the feed ratio of ferric chloride hexahydrate, ferrous sulfate heptahydrate, polystyrene microspheres, polyvinyl pyrrolidone and deionized water is 0.2 mol: 0.1 mmol: 4.5-5.8 g: 5-7 g: 350-400 mL. Under hydrothermal conditions, ferric chloride hexahydrate and ferrous sulfate heptahydrate form ferroferric oxide particles that are adsorbed on the surface of the polystyrene microspheres.

[0017] In the above step A1, the average particle size of the polystyrene microspheres is 15-30 μm. The polystyrene microspheres with this particle size are used as templates to prepare magnetic carriers with a high specific surface area and are conducive to magnetic recovery.

[0018] Beneficial effects of the present invention:

[0019] The recyclable water treatment agent of the invention uses hollow porous magnetic ferrosoferric oxide as a carrier, is substituted by di-n-butylamine and 3-chloropropyltrimethoxysilane to prepare a surface treatment agent, is loaded on the carrier surface through coupling action, utilizes the tertiary amine structure in the surface treatment agent molecule to coordinate with aluminum chloride, forms polyaluminum chloride in situ on the surface under alkaline heat reflux conditions, and forms a quaternary ammonium structure by bromoethanol and the tertiary amine during the polymerization process. Compared with the existing magnetic loaded polyaluminum chloride water treatment agent, the hollow porous carrier has good suspending and dispersing ability in sewage, fully contacts with sewage, and is conducive to flocculation and impurity removal; the surface quaternary ammonium structure increases the initial surface positive charge density, quickly neutralizes with negatively charged particles in sewage, breaks the colloidal stability, forms a charge neutralization-flocculation dual mechanism with polyaluminum chloride, shortens the floc formation time, improves the purification speed, and improves the purification depth; in addition, the coordination effect of the surface treatment agent enables the polyaluminum chloride to be effectively anchored to the carrier, and the hollow large-particle structure thereof can be quickly separated and recovered through an external magnetic field, thereby realizing efficient recovery of the polyaluminum chloride. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0021] Figure 1 This is a curve diagram of turbidity change over time during the sewage treatment process of the present invention. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0023] Example 1, preparation of a recyclable water treatment agent based on polyaluminium chloride, the specific implementation process is as follows:

[0024] (1) Preparation of magnetic carrier

[0025] Step A1: Take ferric chloride hexahydrate, ferrous sulfate heptahydrate and polyvinyl pyrrolidone and dissolve them in deionized water, add polystyrene microspheres and stir and disperse them at a high speed of 600 rpm, add industrial ammonia water to adjust the pH value of the dispersion to 10, introduce compressed air to increase the pressure to 3 bar, and heat to 130°C for reaction for 4.5 hours, wherein the feed ratio of ferric chloride hexahydrate, ferrous sulfate heptahydrate, polystyrene microspheres, polyvinyl pyrrolidone and deionized water is 0.2 mol: 0.1 mmol: 5.8 g: 7 g: 400 mL, and the polystyrene microspheres are selected from PS030000 type raw materials with an average particle size of 30 μm. After cooling, filter, and bake the filter cake at 200°C for 3 hours to obtain a composite precursor.

[0026] Step A2: immerse the composite precursor in dichloromethane, stir at 60 rpm for 24 hours, filter and dry to obtain a magnetic carrier.

[0027] (2) Preparation of recyclable water treatment agents

[0028] Step S1: premix di-n-butylamine, 3-chloropropyltrimethoxysilane and anhydrous toluene in a dry atmosphere, add potassium hydroxide and mix, heat to 100°C and stir to react for 1.6 hours, wherein the feed ratio of di-n-butylamine, 3-chloropropyltrimethoxysilane, potassium hydroxide and anhydrous toluene is 0.1 mol: 0.1 mol: 4 g: 100 mL, filter after cooling, and then evaporate toluene under reduced pressure to obtain a surface treatment agent.

[0029] Step S2: prepare an ethanol aqueous solution with a volume fraction of 30%, premix the surface treatment agent and the ethanol aqueous solution, adjust the pH value to 4 with acetic acid and stir for hydrolysis for 1 hour, add a magnetic carrier and ultrasonically disperse, then stir and couple for 12 hours, wherein the feed ratio of the magnetic carrier, the surface treatment agent and the ethanol aqueous solution is 50g:3.6g:180mL, and finally filter and take the filter cake for washing to obtain a modified carrier.

[0030] Step S3: Mix aluminum chloride hexahydrate, bromoethanol and methanol, add the modified carrier and stir to disperse, heat to 70°C and reflux, slowly add 10% by mass sodium hydroxide aqueous solution and stir to react for 6 hours, wherein the feed ratio of the modified carrier, aluminum chloride hexahydrate, sodium hydroxide, bromoethanol and methanol is 10g:8.5g:3.3g:25mL:200mL, cool, filter and dry to obtain a recyclable water treatment agent.

[0031] Example 2, preparation of a recyclable water treatment agent based on polyaluminium chloride, the specific implementation process is as follows:

[0032] (1) Preparation of magnetic carrier

[0033] Step A1: Take ferric chloride hexahydrate, ferrous sulfate heptahydrate and polyvinyl pyrrolidone and dissolve them in deionized water, add polystyrene microspheres and stir and disperse them at a high speed of 600 rpm, add industrial ammonia water to adjust the pH value of the dispersion to 10, introduce compressed air to increase the pressure to 2.5 bar, and heat to 130°C for reaction for 5 hours, wherein the feed ratio of ferric chloride hexahydrate, ferrous sulfate heptahydrate, polystyrene microspheres, polyvinyl pyrrolidone and deionized water is 0.2 mol: 0.1 mmol: 5.5 g: 7 g: 400 mL, and the polystyrene microspheres are selected from PS030000 type raw materials with an average particle size of 30 μm. After cooling, filter, and bake the filter cake at 200°C for 3 hours to obtain a composite precursor.

[0034] Step A2: immerse the composite precursor in dichloromethane, stir at 60 rpm for 24 hours, filter and dry to obtain a magnetic carrier.

[0035] (2) Preparation of recyclable water treatment agents

[0036] Step S1: premix di-n-butylamine, 3-chloropropyltrimethoxysilane and anhydrous toluene in a dry atmosphere, add potassium hydroxide and mix, heat to 100°C and stir to react for 1.8 hours, wherein the feed ratio of di-n-butylamine, 3-chloropropyltrimethoxysilane, potassium hydroxide and anhydrous toluene is 0.1 mol: 0.1 mol: 3.5 g: 100 mL, filter after cooling, and then evaporate toluene under reduced pressure to obtain a surface treatment agent.

[0037] Step S2: prepare an ethanol aqueous solution with a volume fraction of 30%, premix the surface treatment agent and the ethanol aqueous solution, adjust the pH value to 4 with acetic acid and stir to hydrolyze for 1.2 hours, add a magnetic carrier and ultrasonically disperse, then stir and couple for 12 hours, wherein the feed ratio of the magnetic carrier, the surface treatment agent and the ethanol aqueous solution is 50g:3.9g:180mL, and finally filter and take the filter cake for washing to obtain a modified carrier.

[0038] Step S3: Mix aluminum chloride hexahydrate, bromoethanol and methanol, add the modified carrier and stir to disperse, heat to 70°C and reflux, slowly add 10% by mass sodium hydroxide aqueous solution and stir to react for 6.3h, wherein the feed ratio of the modified carrier, aluminum chloride hexahydrate, sodium hydroxide, bromoethanol and methanol is 10g:9g:3.3g:25mL:200mL, cool, filter and dry to obtain a recyclable water treatment agent.

[0039] Example 3, preparation of a recyclable water treatment agent based on polyaluminium chloride, the specific implementation process is as follows:

[0040] (1) Preparation of magnetic carrier

[0041] Step A1: dissolve ferric chloride hexahydrate, ferrous sulfate heptahydrate and polyvinyl pyrrolidone in deionized water, add polystyrene microspheres and disperse by stirring at 600 rpm, add industrial ammonia water to adjust the pH value of the dispersion to 10, introduce compressed air to increase the pressure to 2 bar, and heat to 120°C for reaction for 6 hours, wherein the feed ratio of ferric chloride hexahydrate, ferrous sulfate heptahydrate, polystyrene microspheres, polyvinyl pyrrolidone and deionized water is 0.2 mol: 0.1 mmol: 4.5 g: 5 g: 350 mL, and the polystyrene microspheres are PS015000 raw materials with an average particle size of 15 μm. After cooling, filter, and bake the filter cake at 200°C for 3 hours to obtain a composite precursor.

[0042] Step A2: immerse the composite precursor in dichloromethane, stir at 60 rpm for 24 hours, filter and dry to obtain a magnetic carrier.

[0043] (2) Preparation of recyclable water treatment agents

[0044] Step S1: premix di-n-butylamine, 3-chloropropyltrimethoxysilane and anhydrous toluene in a dry atmosphere, add potassium hydroxide and mix, heat to 80°C and stir to react for 2.2h, wherein the feed ratio of di-n-butylamine, 3-chloropropyltrimethoxysilane, potassium hydroxide and anhydrous toluene is 0.1mol:0.1mol:2.5g:70mL, filter after cooling, and then evaporate toluene under reduced pressure to obtain a surface treatment agent.

[0045] Step S2: prepare an ethanol aqueous solution with a volume fraction of 40%, premix the surface treatment agent and the ethanol aqueous solution, adjust the pH value to 4 with acetic acid and stir to hydrolyze for 1.5 hours, add a magnetic carrier and ultrasonically disperse, then stir and couple for 12 hours, wherein the feed ratio of the magnetic carrier, the surface treatment agent and the ethanol aqueous solution is 50g:4.8g:130mL, and finally filter and take the filter cake for washing to obtain a modified carrier.

[0046] Step S3: Mix aluminum chloride hexahydrate, bromoethanol and methanol, add the modified carrier, stir and disperse, heat to 60°C and reflux, slowly add 8% by mass sodium hydroxide aqueous solution and stir to react for 8 hours, wherein the feed ratio of the modified carrier, aluminum chloride hexahydrate, sodium hydroxide, bromoethanol and methanol is 10g:10.2g:2.6g:20mL:150mL, cool, filter and dry to obtain a recyclable water treatment agent.

[0047] Example 4, preparation of a recyclable water treatment agent based on polyaluminium chloride, the specific implementation process is as follows:

[0048] (1) Preparation of magnetic carrier

[0049] Step A1: dissolve ferric chloride hexahydrate, ferrous sulfate heptahydrate and polyvinyl pyrrolidone in deionized water, add polystyrene microspheres and disperse by stirring at a high speed of 600 rpm, add industrial ammonia water to adjust the pH value of the dispersion to 10, introduce compressed air to increase the pressure to 2.5 bar, and heat to 125°C for reaction for 5.5 hours, wherein the feed ratio of ferric chloride hexahydrate, ferrous sulfate heptahydrate, polystyrene microspheres, polyvinyl pyrrolidone and deionized water is 0.2 mol: 0.1 mmol: 4.8 g: 6 g: 380 mL, and the polystyrene microspheres are PS015000 raw materials with an average particle size of 15 μm. After cooling, filter, and bake the filter cake at 200°C for 3 hours to obtain a composite precursor.

[0050] Step A2: immerse the composite precursor in dichloromethane, stir at 60 rpm for 24 hours, filter and dry to obtain a magnetic carrier.

[0051] (2) Preparation of recyclable water treatment agents

[0052] Step S1: premix di-n-butylamine, 3-chloropropyltrimethoxysilane and anhydrous toluene in a dry atmosphere, add potassium hydroxide and mix, heat to 90°C and stir to react for 1.8h, wherein the feed ratio of di-n-butylamine, 3-chloropropyltrimethoxysilane, potassium hydroxide and anhydrous toluene is 0.1mol:0.1mol:3.2g:90mL, filter after cooling, and then evaporate toluene under reduced pressure to obtain a surface treatment agent.

[0053] Step S2: prepare an ethanol aqueous solution with a volume fraction of 40%, premix the surface treatment agent and the ethanol aqueous solution, adjust the pH value to 4 with acetic acid and stir to hydrolyze for 1.3 hours, add a magnetic carrier and ultrasonically disperse, then stir and couple for 12 hours, wherein the feed ratio of the magnetic carrier, the surface treatment agent and the ethanol aqueous solution is 50g:4.4g:160mL, and finally filter and take the filter cake for washing to obtain a modified carrier.

[0054] Step S3: Mix aluminum chloride hexahydrate, bromoethanol and methanol, add the modified carrier, stir and disperse, heat to 65°C and reflux, slowly add 8% sodium hydroxide aqueous solution by mass and stir to react for 7.5 hours, wherein the feed ratio of the modified carrier, aluminum chloride hexahydrate, sodium hydroxide, bromoethanol and methanol is 10g:9.8g:3g:25mL:180mL, cool, filter and dry to obtain a recyclable water treatment agent.

[0055] In comparative example 1, industrial grade polyaluminium chloride produced by Ningbo Shunfan Water Purifier Co., Ltd. was selected.

[0056] Comparative Example 2, referring to the prior art, a magnetic water treatment agent was prepared by a sol method, specifically:

[0057] Take nano-ferroferric oxide and ultrasonically disperse it in distilled water, add sodium carboxymethyl cellulose and stir to dissolve to make a dispersion, then take polyaluminium chloride and dissolve it in deionized water, heat it to 45°C, stir at 300rpm, slowly add the dispersion to mix, and then let it stand for 24 hours, wherein the feed ratio of nano-ferroferric oxide, polyaluminium chloride, sodium carboxymethyl cellulose, distilled water and deionized water is 10g:3.5g:1.8g:50mL:30mL, then remove the supernatant, dry the substrate, grind and crush it to obtain ferroferric oxide / polyaluminium chloride magnetic water treatment agent.

[0058] Sampling was performed from the water treatment agent prepared as above to conduct sewage purification test and water treatment agent recovery test, specifically:

[0059] Wastewater purification test: Mining wastewater was selected as the purification object, and a sedimentation platform with a diameter of 20 cm and a depth of 50 cm was set up. A water purifier was added to the wastewater according to the aluminum ion content of 15 mg / kg, stirred for 10 minutes, and the wastewater turbidity was tested. The specific turbidity changes were as follows: Figure 1 As shown;

[0060] Recovery rate test: After 24 hours of purification, the supernatant was removed from the sewage, and the bottom flocculants were repeatedly adsorbed three times using an electromagnet with a magnetic field strength of 0.5T. The adsorbed flocculants were dissolved with nitric acid, and the aluminum ion content was detected. The recovery rate was calculated as the amount of adsorbed aluminum ions / the amount of aluminum ions added × 100%. The specific test results are shown in Table 1:

[0061] Table 1

[0062]

[0063] Combination Figure 1 As can be seen from the data in Table 1, the water treatment agent prepared in the embodiment has a high degree of sewage purification, and the purification cycle is almost completed in 10 minutes, showing excellent and efficient water purification ability, and the magnetic absorption recovery rate reaches more than 80%, achieving effective recovery.

[0064] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0065] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a recyclable water treatment agent based on polyaluminium chloride, characterized in that: The steps include: Step S1: premix di-n-butylamine, 3-chloropropyltrimethoxysilane and anhydrous toluene in a dry atmosphere, add potassium hydroxide and mix, heat to 80-100° C. and stir to react for 1.6-2.2 hours to prepare a surface treatment agent; Step S2: premixing the surface treatment agent and ethanol aqueous solution, adjusting the pH value to 4 with acetic acid and stirring for hydrolysis for 1-1.5 hours, adding the magnetic carrier and ultrasonically dispersing, stirring and coupling for 12 hours to prepare a modified carrier; Step S3: dissolving aluminum chloride hexahydrate, bromoethanol and methanol, adding the modified carrier, stirring and dispersing, heating to 60-70° C. and refluxing, slowly adding sodium hydroxide aqueous solution, stirring and reacting for 6-8 hours, and preparing a recyclable water treatment agent.

2. The method for preparing a recyclable water treatment agent based on polyaluminium chloride according to claim 1, characterized in that: The feed ratio of di-n-butylamine, 3-chloropropyltrimethoxysilane, potassium hydroxide and anhydrous toluene is 0.1 mol: 0.1 mol: 2.5-4 g: 70-100 mL.

3. The method for preparing a recyclable water treatment agent based on polyaluminium chloride according to claim 2, characterized in that: The feeding ratio of the magnetic carrier, the surface treatment agent and the ethanol aqueous solution is 50g:3.6-4.8g:130-180mL, and the volume fraction of the ethanol aqueous solution is 30-40%.

4. The method for preparing a recyclable water treatment agent based on polyaluminium chloride according to claim 3, characterized in that: The feed ratio of the modified carrier, aluminum chloride hexahydrate, sodium hydroxide, bromoethanol and methanol is 10g:8.5-10.2g:2.6-3.3g:20-25mL:150-200mL.

5. The method for preparing a recyclable water treatment agent based on polyaluminium chloride according to claim 1, characterized in that: The magnetic carrier is made by the following steps: Step A1: dissolving ferric chloride hexahydrate, ferrous sulfate heptahydrate and polyvinyl pyrrolidone in deionized water, adding polystyrene microspheres and stirring to disperse, adjusting the pH value of the dispersion to 10 with ammonia water, pressurizing the reaction system to 2-3 bar, heating to 120-130° C. and reacting for 4.5-6 hours, cooling and filtering, and drying the filter cake at 200° C. to obtain a composite precursor; Step A2: immerse the composite precursor in dichloromethane and stir for 24 hours, filter and dry to obtain a magnetic carrier.

6. The method for preparing a recyclable water treatment agent based on polyaluminium chloride according to claim 5, characterized in that: The feed ratio of ferric chloride hexahydrate, ferrous sulfate heptahydrate, polystyrene microspheres, polyvinyl pyrrolidone and deionized water is 0.2 mol: 0.1 mmol: 4.5-5.8 g: 5-7 g: 350-400 mL.

7. The method for preparing a recyclable water treatment agent based on polyaluminium chloride according to claim 6, characterized in that: The average particle size of polystyrene microspheres is 15-30 μm.

8. A recyclable water treatment agent based on polyaluminium chloride, characterized in that: The method is prepared by any one of claims 1 to 7.

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