A method for preparing polyaluminium chloride based on electrolytic brine

Abstract

The invention discloses a method for preparing polyaluminium chloride based on electrolytic brine, comprising the following steps: preparing a porous ion adsorption membrane; performing ammonia treatment after preliminary impurity removal of brine, and then pumping it into a reactor loaded with a porous ion adsorption membrane for refined treatment, electrolysing the brine after refined treatment to obtain hydrogen and chlorine, and preparing hydrogen chloride by a mixed reaction of chlorine and hydrogen, and using pure water to absorb hydrogen chloride to prepare hydrochloric acid solution; adding bauxite and hydrochloric acid solution into the reactor for temperature rise reflux reaction, cooling to room temperature after the reaction is completed, filtering, collecting the filtrate, and adding calcium aluminate powder to the filtrate to adjust the product basicity to 45-65%, continuing to stir the reaction, filtering after the reaction is completed, and preparing liquid polyaluminium chloride after the filtrate is matured. The method provided by the present invention is simple to operate, and the obtained polyaluminium chloride has good performance, meets national standards, and has low preparation cost.

Description

Technical Field

[0001] The invention relates to the technical field of brine treatment, and in particular to a method for preparing polyaluminium chloride based on electrolysis of brine. Background Art

[0002] Polyaluminium chloride is an inorganic substance, a new water purification material, and an inorganic polymer coagulant. Polyaluminium chloride has the advantages of good stability, wide adaptability to water areas, fast hydrolysis rate, strong adsorption capacity, low effluent turbidity, and good dehydration performance. Under the same water quality conditions, the amount of polyaluminium chloride added is reduced, which greatly reduces the water treatment cost. At present, the preparation method of polyaluminium chloride is mainly based on hydrochloric acid, bauxite and calcium aluminate powder as raw materials, but a large amount of hydrochloric acid will be used in the process, thereby increasing the preparation cost of polyaluminium chloride. Summary of the invention

[0003] The technical problem to be solved by the present invention is: in view of the shortcomings of the prior art, a method for preparing polyaluminium chloride based on electrolytic brine is provided, the method is simple to operate, the prepared polyaluminium chloride has good performance, meets national standards, and has low preparation cost.

[0004] In order to solve the above technical problems, the technical solution of the present invention is:

[0005] A method for preparing polyaluminium chloride based on electrolysis of brine comprises the following steps:

[0006] (1) adding bis(1,5-cyclozincdiene)nickel, 2,2'-bipyridine, DMF and 1,5-cyclodiene into a reactor, and performing a first reaction under the protection of an inert gas, and then adding tetra(4-bromophenyl)methane, and continuing a second reaction. After the reaction is completed, the reaction system is cooled to room temperature, and a hydrochloric acid solution is added dropwise into the reaction system, and the reaction system is stirred at room temperature. Finally, the reaction solution is filtered, and the precipitate obtained by filtration is washed and dried to obtain a porous aromatic framework material;

[0007] (2) adding the porous aromatic framework material, paraformaldehyde and acid solution prepared above into a reactor, heating and stirring to react, cooling to room temperature after the reaction is completed, filtering the reaction solution, washing the obtained precipitate and vacuum drying, mixing the obtained solid with meglumine and DMF and adding them into a reactor for reaction, filtering the reaction solution after the reaction is completed, washing the filtered precipitate and vacuum drying to obtain a functionalized porous material;

[0008] (3) dissolving 3-sulfopropyl methacrylate potassium salt in deionized water, then adding a crosslinking agent and stirring until the solution is mushy, adding an initiator, and mixing evenly to obtain a prepolymer solution, adding the functionalized porous material prepared above to the prepolymer solution, stirring and dispersing, then performing an ultrasonic treatment, and finally performing a degassing treatment, and pouring the degassed solution on a substrate for reaction, after the reaction is completed, removing the formed film on the substrate and soaking it in deionized water, and then taking it out and soaking it in a 1 mol / L sodium chloride solution to obtain a porous ion adsorption membrane;

[0009] (4) After preliminary impurity removal, the brine is subjected to ammonia removal treatment, and then pumped into a reactor loaded with the porous ion adsorption membrane prepared above for refining treatment, the refined brine is electrolyzed to produce hydrogen and chlorine, the chlorine and hydrogen are mixed to react to produce hydrogen chloride, and pure water is used to absorb the hydrogen chloride to produce a hydrochloric acid solution;

[0010] (5) Adding bauxite and hydrochloric acid solution into a reactor for heating and reflux reaction, cooling to room temperature after the reaction, filtering, collecting the filtrate, and adding calcium aluminate powder to the filtrate to adjust the product basicity to 45-65%, continuing to stir the reaction, filtering after the reaction is completed, and preparing liquid polyaluminium chloride after the filtrate is aged.

[0011] As a preferred embodiment of the above technical solution, in step (1), the concentration of the hydrochloric acid solution is 6 mol / L, and the dosage ratio of the bis(1,5-cyclozincdiene)nickel, 2,2'-bipyridine, DMF, 1,5-cyclodiene, hydrochloric acid solution: tetra(4-bromophenyl)methane is 2g:(1-1.5)g:110ml:(0.5-1)ml:50ml:(0.9-1)g.

[0012] As a preferred embodiment of the above technical solution, in step (1), the temperature of the first reaction and the second reaction are both 75-85°C, the time of the first reaction is 1-2h, and the time of the second reaction is 10-15h; the stirring speed at room temperature is 1000-2000 rpm, and the time is 2-5h.

[0013] As a preferred embodiment of the above technical solution, in step (2), the acid solution is a mixture of glacial acetic acid, phosphoric acid and hydrochloric acid solution, and the volume ratio of the three is 9:(4-5):30, and the concentration of the hydrochloric acid solution is 12 mol / L; the dosage ratio of the porous aromatic framework material, paraformaldehyde and acid solution is (0.3-0.5) g:(1-2) g:(40-45) ml; the temperature of the heating and stirring reaction is 90°C, and the time is 3-4 days.

[0014] As a preferred embodiment of the above technical solution, in step (2), the mass ratio of the solid, meglumine and DMF when mixed is 0.3g:(10-15)g:(40-50)g; the reaction temperature is 90°C and the reaction time is 3-4 days.

[0015] As a preferred embodiment of the above technical solution, in step (3), the cross-linking agent is glycerol dimethacrylate, the initiator is azobisisobutyramidine hydrochloride, and the usage ratio of 3-sulfonate propyl methacrylate potassium salt, deionized water, cross-linking agent, initiator, and functionalized porous material is 1g:20ml:(0.2-0.5)g:(0.01-0.02)g:(0.1-0.3)g.

[0016] As a preferred embodiment of the above technical solution, in step (3), the stirring and dispersing speed is 3000 rpm, and the time is 5-10 min; the temperature of the ultrasonic treatment is less than 20°C, the ultrasonic power is 300-500W, and the time is 5-10 min; the temperature of the reaction is 80-90°C, and the time is 30-60 min.

[0017] As a preferred embodiment of the above technical solution, in step (3), the molded film is immersed in deionized water and sodium chloride solution for 24 hours, and the deionized water or sodium chloride solution needs to be replaced 2-3 times during the immersion process.

[0018] As a preferred embodiment of the above technical solution, in step (4), the temperature of the mixed reaction of chlorine and hydrogen is 700-800°C, and the concentration of the hydrochloric acid solution is controlled to be 10-15wt%.

[0019] As a preferred embodiment of the above technical solution, in step (5), the mass ratio of bauxite to acid solution is 1:4, the temperature rising reflux reaction is 130°C, and the time is 5-7h; the temperature of the stirring reaction is 130°C, the stirring speed is 300-500 rpm, and the time is 1-2h; the aging temperature is 60-70°C, and the time is 20-40h.

[0020] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0021] The present invention uses brine as a raw material, first removes ammonia from the brine, then performs refining and purification to remove metal ions in the brine, then electrolyzes the refined and purified brine, collects chlorine and hydrogen, and performs mixed combustion, and the generated hydrogen chloride gas is absorbed by water to obtain a hydrochloric acid solution, which is mixed with bauxite and calcium aluminate powder to react to obtain polyaluminium chloride. The method is simple to operate and has a low preparation cost.

[0022] The present invention prepares a porous aromatic hydrocarbon skeleton material with chelating properties with metal ions, and then adds the porous aromatic hydrocarbon skeleton material into a prepolymer solution mixed with a charged monomer, a crosslinking agent and an initiator. The free radicals of the charged monomer and the crosslinking agent are uniformly dispersed around the porous aromatic hydrocarbon skeleton material to form a crosslinked ion exchange network, thereby obtaining a porous ion adsorption membrane with good dispersibility. When refining brine, the porous ion adsorption membrane can effectively remove metal ions in the brine, thereby purifying the brine and facilitating subsequent treatment. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0024] Example 1

[0025] (1) 2 g of bis(1,5-cyclozincdiene)nickel, 1.2 g of 2,2'-bipyridine, 110 ml of DMF, and 0.9 ml of 1,5-cyclodiene were added into a reactor, and the mixture was reacted at 75° C. for 1 h under inert gas protection, and then 0.93 g of tetra(4-bromophenyl)methane was added, and the reaction was continued for 10 h. After the reaction was completed, the mixture was cooled to room temperature, and 50 ml of 6 mol / L hydrochloric acid solution was added dropwise into the reaction system, and the mixture was stirred at room temperature and 1000 rpm for 2 h. Finally, the reaction solution was filtered, and the precipitate obtained by filtration was washed and dried to obtain a porous aromatic framework material;

[0026] (2) glacial acetic acid, phosphoric acid, and 12 mol / L hydrochloric acid solution are mixed in a volume ratio of 9:4:30 to prepare an acid solution, 0.3 g of the porous aromatic framework material prepared above, 1.3 g of paraformaldehyde, and 40 ml of the acid solution are added to a reactor, the temperature is raised to 90° C., and the mixture is stirred for reaction for 3 days. After the reaction is completed, the mixture is cooled to room temperature, the reaction solution is filtered, the obtained precipitate is washed, and vacuum dried, the obtained solid and meglumine and DMF are mixed in a mass ratio of 0.3 g:11 g:40 g, and the mixture is added to a reactor at 90° C. for reaction for 3 days. After the reaction is completed, the reaction solution is filtered, the filtered precipitate is washed, and vacuum dried to obtain a functionalized porous material;

[0027] (3) Dissolve 1 g of 3-sulfonic acid propyl methacrylate potassium salt in 20 ml of deionized water, then add 0.2 g of glycerol dimethacrylate and stir to mix, add 0.01 g of azobisisobutylamidine hydrochloride, mix well to obtain a prepolymer solution, add 0.1 g of the functionalized porous material prepared above to the prepolymer solution, stir and disperse at 3000 rpm for 5 min, then perform ultrasonic treatment at 300 W for 5 min, the temperature during the ultrasonic treatment should not exceed 20° C., finally perform degassing treatment, cast the degassed solution on a substrate and react at 80° C. for 30 min. After the reaction, remove the formed film on the substrate and soak it in deionized water for 24 h, during which the deionized water is replaced 2-3 times, then take it out and soak it in 1 mol / L sodium chloride solution for 24 h, during which the sodium chloride solution is replaced 2-3 times, to obtain a porous ion adsorption membrane;

[0028] (4) After the brine is initially impurity-removed and ammonia-removed, it is then pumped into a reactor loaded with the porous ion adsorption membrane prepared above for refining treatment, the refined brine is electrolyzed to produce hydrogen and chlorine, the chlorine and hydrogen are mixed and burned at 700° C. to produce hydrogen chloride, and pure water is used to absorb the hydrogen chloride to produce a hydrochloric acid solution with a concentration of 15 wt%;

[0029] (5) Bauxite and hydrochloric acid solution are added into a reactor in a mass ratio of 1:4, and the temperature is raised to 130° C. and refluxed for 5 h. After the reaction is completed, the mixture is cooled to room temperature and filtered, and the filtrate is collected. Calcium aluminate powder is added to the filtrate to adjust the product basicity to 55%. The mixture is stirred and reacted at 130° C. and 300 rpm for 1 h. After the reaction is completed, the mixture is filtered, and the filtrate is aged at 60° C. for 36 h to obtain liquid polyaluminium chloride.

[0030] Example 2

[0031] (1) 2 g of bis(1,5-cyclozincdiene)nickel, 1.2 g of 2,2'-bipyridine, 110 ml of DMF, and 0.9 ml of 1,5-cyclodiene were added into a reactor, and reacted at 80° C. for 1 h under inert gas protection, and then 0.93 g of tetra(4-bromophenyl)methane was added, and the reaction was continued for 12 h. After the reaction was completed, the reaction system was cooled to room temperature, and 50 ml of 6 mol / L hydrochloric acid solution was added dropwise into the reaction system, and stirred at room temperature and 1500 rpm for 3 h. Finally, the reaction solution was filtered, and the precipitate obtained by filtration was washed and dried to obtain a porous aromatic framework material;

[0032] (2) glacial acetic acid, phosphoric acid, and 12 mol / L hydrochloric acid solution were mixed in a volume ratio of 9:4.5:30 to prepare an acid solution, 0.4 g of the porous aromatic framework material prepared above, 1.5 g of paraformaldehyde, and 43 ml of the acid solution were added to a reactor, the temperature was raised to 90° C., and the mixture was stirred for reaction for 3 days. After the reaction was completed, the mixture was cooled to room temperature, the reaction solution was filtered, the obtained precipitate was washed, and vacuum dried, the obtained solid and meglumine and DMF were mixed in a mass ratio of 0.3 g:12 g:45 g, and added to a reactor for reaction at 90° C. for 3 days. After the reaction was completed, the reaction solution was filtered, the filtered precipitate was washed, and vacuum dried to obtain a functionalized porous material;

[0033] (3) Dissolve 1g of 3-sulfonic acid propyl methacrylate potassium salt in 20ml of deionized water, then add 0.3g of glycerol dimethacrylate and stir to mix, add 0.015g of azobisisobutylamidine hydrochloride, mix well to obtain a prepolymer solution, add 0.15g of the functionalized porous material prepared above to the prepolymer solution, stir and disperse at 3000 rpm for 5-10min, then perform ultrasonic treatment at 300-500W for 5-10min, the temperature during the ultrasonic treatment should not exceed 20°C, and finally perform degassing treatment. The degassed solution is cast on a substrate and reacted at 85°C for 40min. After the reaction, the formed film on the substrate is removed and immersed in deionized water for 24h, during which the deionized water is replaced 2-3 times, and then taken out and immersed in 1mol / L sodium chloride solution for 24h, during which the sodium chloride solution is replaced 2-3 times, to obtain a porous ion adsorption membrane;

[0034] (4) After the brine is initially impurity-removed and ammonia-removed, it is then pumped into a reactor loaded with the porous ion adsorption membrane prepared above for refining treatment, the refined brine is electrolyzed to produce hydrogen and chlorine, the chlorine and hydrogen are mixed and burned at 700° C. to produce hydrogen chloride, and pure water is used to absorb the hydrogen chloride to produce a hydrochloric acid solution with a concentration of 15 wt%;

[0035] (5) Bauxite and hydrochloric acid solution are added into a reactor in a mass ratio of 1:4, and the temperature is raised to 130°C for reflux reaction for 6 hours. After the reaction is completed, the mixture is cooled to room temperature and filtered, and the filtrate is collected. Calcium aluminate powder is added to the filtrate to adjust the product basicity to 60%. The mixture is stirred and reacted at 130°C and 350 rpm for 2 hours. After the reaction is completed, the mixture is filtered, and the filtrate is aged at 65°C for 36 hours to obtain liquid polyaluminium chloride.

[0036] Example 3

[0037] (1) 2 g of bis(1,5-cyclozincdiene)nickel, 1.2 g of 2,2'-bipyridine, 110 ml of DMF, and 0.9 ml of 1,5-cyclodiene were added into a reactor, and reacted at 80° C. for 2 h under inert gas protection, and then 0.93 g of tetra(4-bromophenyl)methane was added, and the reaction was continued for 12 h. After the reaction was completed, the reaction system was cooled to room temperature, and 50 ml of 6 mol / L hydrochloric acid solution was added dropwise into the reaction system, and stirred at room temperature and 2000 rpm for 3 h. Finally, the reaction solution was filtered, and the precipitate obtained by filtration was washed and dried to obtain a porous aromatic framework material;

[0038] (2) glacial acetic acid, phosphoric acid, and 12 mol / L hydrochloric acid solution were mixed in a volume ratio of 9:4:30 to prepare an acid solution, 0.35 g of the porous aromatic framework material prepared above, 1.3 g of paraformaldehyde, and 45 ml of the acid solution were added to a reactor, the temperature was raised to 90° C., and the mixture was stirred for reaction for 3 days. After the reaction was completed, the mixture was cooled to room temperature, the reaction solution was filtered, the obtained precipitate was washed, and vacuum dried, the obtained solid and meglumine and DMF were mixed in a mass ratio of 0.3 g:12 g:40 g, and added to a reactor for reaction at 90° C. for 3 days. After the reaction was completed, the reaction solution was filtered, the filtered precipitate was washed, and vacuum dried to obtain a functionalized porous material;

[0039] (3) Dissolve 1 g of 3-sulfonic acid propyl methacrylate potassium salt in 20 ml of deionized water, then add 0.33 g of glycerol dimethacrylate and stir to mix, add 0.012 g of azobisisobutylamidine hydrochloride, mix well to obtain a prepolymer solution, add 0.2 g of the functionalized porous material prepared above to the prepolymer solution, stir and disperse at 3000 rpm for 5 min, then perform ultrasonic treatment at 400 W for 5 min, the temperature during the ultrasonic treatment should not exceed 20° C., finally perform degassing treatment, cast the degassed solution on a substrate and react at 85° C. for 40 min. After the reaction, remove the formed film on the substrate and soak it in deionized water for 24 h, during which the deionized water is replaced 2-3 times, then take it out and soak it in 1 mol / L sodium chloride solution for 24 h, during which the sodium chloride solution is replaced 2-3 times, to obtain a porous ion adsorption membrane;

[0040] (4) After the brine is initially impurity-removed and ammonia-removed, it is then pumped into a reactor loaded with the porous ion adsorption membrane prepared above for refining treatment, the refined brine is electrolyzed to produce hydrogen and chlorine, the chlorine and hydrogen are mixed and burned at 700° C. to produce hydrogen chloride, and pure water is used to absorb the hydrogen chloride to produce a hydrochloric acid solution with a concentration of 15 wt%;

[0041] (5) Bauxite and hydrochloric acid solution are added into a reactor in a mass ratio of 1:4, and the temperature is raised to 130° C. and refluxed for 6 hours. After the reaction is completed, the mixture is cooled to room temperature and filtered, and the filtrate is collected. Calcium aluminate powder is added to the filtrate to adjust the product basicity to 65%. The mixture is stirred and reacted at 130° C. and 500 rpm for 1 hour. After the reaction is completed, the mixture is filtered, and the filtrate is aged at 60° C. for 36 hours to obtain liquid polyaluminium chloride.

[0042] Example 4

[0043] (1) 2 g of bis(1,5-cyclozincdiene)nickel, 1.2 g of 2,2'-bipyridine, 110 ml of DMF, and 0.9 ml of 1,5-cyclodiene were added into a reactor, and the mixture was reacted at 80° C. for 1 h under inert gas protection, and then 0.93 g of tetra(4-bromophenyl)methane was added, and the reaction was continued for 12 h. After the reaction was completed, the mixture was cooled to room temperature, and 50 ml of 6 mol / L hydrochloric acid solution was added dropwise into the reaction system, and the mixture was stirred at room temperature and 1000 rpm for 3 h. Finally, the reaction solution was filtered, and the precipitate obtained by filtration was washed and dried to obtain a porous aromatic framework material;

[0044] (2) glacial acetic acid, phosphoric acid, and 12 mol / L hydrochloric acid solution were mixed in a volume ratio of 9:4:30 to prepare an acid solution, 0.35 g of the porous aromatic framework material prepared above, 1.5 g of paraformaldehyde, and 42 ml of the acid solution were added to a reactor, the temperature was raised to 90° C., and the mixture was stirred for reaction for 3 days. After the reaction was completed, the mixture was cooled to room temperature, the reaction solution was filtered, the obtained precipitate was washed, and vacuum dried, the obtained solid and meglumine and DMF were mixed in a mass ratio of 0.3 g:12 g:47 g, and added to a reactor for reaction at 90° C. for 3 days. After the reaction was completed, the reaction solution was filtered, the filtered precipitate was washed, and vacuum dried to obtain a functionalized porous material;

[0045] (3) Dissolve 1 g of 3-sulfonic acid propyl methacrylate potassium salt in 20 ml of deionized water, then add 0.4 g of glycerol dimethacrylate and stir to mix, add 0.015 g of azobisisobutylamidine hydrochloride, mix well to obtain a prepolymer solution, add 0.2 g of the functionalized porous material prepared above to the prepolymer solution, stir and disperse at 3000 rpm for 5 min, then perform ultrasonic treatment at 300 W for 5 min, the temperature during the ultrasonic treatment should not exceed 20° C., finally perform degassing treatment, cast the degassed solution on a substrate and react at 85° C. for 40 min. After the reaction, remove the formed film on the substrate and soak it in deionized water for 24 h, during which the deionized water is replaced 2-3 times, then take it out and soak it in 1 mol / L sodium chloride solution for 24 h, during which the sodium chloride solution is replaced 2-3 times, to obtain a porous ion adsorption membrane;

[0046] (4) After the brine is initially impurity-removed and ammonia-removed, it is then pumped into a reactor loaded with the porous ion adsorption membrane prepared above for refining treatment, the refined brine is electrolyzed to produce hydrogen and chlorine, the chlorine and hydrogen are mixed and burned at 700° C. to produce hydrogen chloride, and pure water is used to absorb the hydrogen chloride to produce a hydrochloric acid solution with a concentration of 15 wt%;

[0047] (5) Bauxite and hydrochloric acid solution are added into a reactor in a mass ratio of 1:4, and the temperature is raised to 130°C for reflux reaction for 5-7 hours. After the reaction is completed, the mixture is cooled to room temperature and filtered, and the filtrate is collected. Calcium aluminate powder is added to the filtrate to adjust the product basicity to 65%. The mixture is stirred and reacted at 130°C and 500 rpm for 2 hours. After the reaction is completed, the mixture is filtered, and the filtrate is aged at 60°C for 36 hours to obtain liquid polyaluminium chloride.

[0048] The polyaluminium chloride prepared in the above embodiment has an aluminium oxide content of 12-13% and a basicity of 55-65%, which are in line with national standards.

[0049] In addition, it should be understood that after reading the contents of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing polyaluminium chloride based on electrolysis of brine, characterized in that: The following steps are involved: (1) Adding bis(1,5-cyclozincadiene)nickel, 2,2'-bipyridine, DMF and 1,5-cyclodiene into a reactor, and performing a first reaction under the protection of an inert gas, then adding tetra(4-bromophenyl)methane, and continuing a second reaction. After the reaction is completed, the reaction system is cooled to room temperature, and a hydrochloric acid solution is added dropwise to the reaction system, and the reaction system is stirred at room temperature. Finally, the reaction solution is filtered, and the precipitate obtained by filtration is washed and dried to obtain a porous aromatic framework material; the concentration of the hydrochloric acid solution is 6 mol / L, and the bis(1,5-cyclozincadiene)nickel is 6 mol / L. The dosage ratio of nickel (diene), 2,2'-bipyridine, DMF, 1,5-cyclodiene, hydrochloric acid solution: tetra(4-bromophenyl)methane is 2g: (1-1.5)g: 110ml: (0.5-1)ml: 50ml: (0.9-1)g; the temperature of the first reaction and the second reaction are both 75-85°C, the time of the first reaction is 1-2h, and the time of the second reaction is 10-15h; the speed of stirring at room temperature is 1000-2000 rpm, and the time is 2-5h; (2) Adding the above-mentioned porous aromatic framework material, polyformaldehyde and acid solution into a reactor, heating and stirring to react, cooling to room temperature after the reaction, filtering the reaction solution, washing the obtained precipitate and vacuum drying, mixing the obtained solid with meglumine and DMF and adding them into the reactor for reaction, filtering the reaction solution after the reaction, washing the filtered precipitate and vacuum drying to obtain a functionalized porous material; the acid solution is a mixture of glacial acetic acid, phosphoric acid and hydrochloric acid solution, the volume ratio of the three is 9: (4-5): 30, and the concentration of the hydrochloric acid solution is 12 mol / L; the amount ratio of the porous aromatic framework material, polyformaldehyde and acid solution is (0.3-0.5) g: (1-2) g: (40-45) ml; the temperature of the heating and stirring reaction is 90°C and the time is 3-4 days; (3) Dissolving 3-sulfopropyl methacrylate potassium salt in deionized water, then adding a crosslinking agent and stirring and mixing, adding an initiator, and mixing evenly to obtain a prepolymer solution, adding the above-mentioned functional porous material to the prepolymer solution, stirring and dispersing, then performing ultrasonic treatment, and finally performing degassing treatment, and pouring the degassed solution on a substrate for reaction, after the reaction is completed, removing the formed film on the substrate and soaking it in deionized water, and then taking it out and soaking it in a 1 mol / L sodium chloride solution to obtain a porous ion adsorption membrane; (4) After the brine is initially impurity-removed, it is subjected to ammonia removal treatment, and then pumped into a reactor loaded with the above-mentioned porous ion adsorption membrane for refining treatment, the refined brine is electrolyzed to produce hydrogen and chlorine, the chlorine and hydrogen are mixed to react to produce hydrogen chloride, and pure water is used to absorb the hydrogen chloride to produce a hydrochloric acid solution; (5) Add bauxite and hydrochloric acid solution into the reactor for heating and reflux reaction. After the reaction is completed, cool to room temperature and filter. Collect the filtrate and add calcium aluminate powder to the filtrate to adjust the product basicity to 45-65%. Continue stirring the reaction. After the reaction is completed, filter. After the filtrate is matured, liquid polyaluminium chloride is obtained.

2. A method for preparing polyaluminium chloride based on electrolytic brine according to claim 1, characterized in that: In step (2), the mass ratio of the solid, meglumine and DMF when mixed is 0.3 g: (10-15) g: (40-50) g; the reaction temperature is 90° C. and the reaction time is 3-4 days.

3. A method for preparing polyaluminium chloride based on electrolytic brine according to claim 1, characterized in that: In step (3), the cross-linking agent is glycerol dimethacrylate, the initiator is azobisisobutylamidine hydrochloride, and the dosage ratio of 3-sulfonic acid propyl methacrylate potassium salt, deionized water, cross-linking agent, initiator, and functionalized porous material is 1g:20ml:(0.2-0.5)g:(0.01-0.02)g:(0.1-0.3)g.

4. A method for preparing polyaluminium chloride based on electrolytic brine according to claim 1, characterized in that: In step (3), the stirring and dispersing speed is 3000 rpm, and the time is 5-10 min; the temperature of the ultrasonic treatment is less than 20°C, the ultrasonic power is 300-500W, and the time is 5-10 min; the temperature of the reaction is 80-90°C, and the time is 30-60 min.

5. A method for preparing polyaluminium chloride based on electrolytic brine according to claim 1, characterized in that: In step (3), the molded membrane is immersed in deionized water and sodium chloride solution for 24 hours, and the deionized water or sodium chloride solution needs to be replaced 2-3 times during the immersion process.

6. The method for preparing polyaluminium chloride based on electrolytic brine according to claim 1, characterized in that: In step (4), the temperature of the mixed reaction of chlorine and hydrogen is 700-800°C, and the concentration of the hydrochloric acid solution is controlled to be 10-15wt%.

7. A method for preparing polyaluminium chloride based on electrolysis of brine according to claim 1, characterized in that: In step (5), the mass ratio of bauxite to acid solution is 1:4, the temperature of the reflux reaction is 130°C, and the time is 5-7h; the temperature of the stirring reaction is 130°C, the stirring speed is 300-500 rpm, and the time is 1-2h; the temperature of the aging reaction is 60-70°C, and the time is 20-40h.