1127 results about "Piperazine" patented technology

The invention discloses an organic amine composite absorbent for carbon capture and application thereof, and belongs to the technical field of carbon dioxide capture, the organic amine composite absorbent for carbon capture is in a solution state and comprises the following components: a main agent, an auxiliary agent, an accelerant A, an accelerant B and water; wherein the mass ratio of the main agent to the auxiliary agent is 2: (1-2); the mass ratio of the auxiliary agent to the accelerant A is 2: (1-2); the mass ratio of the accelerant A to the accelerant B is 2: (1-2); the total mass concentration of the main agent, the auxiliary agent, the accelerant A and the accelerant B in the organic amine composite absorbent for carbon capture is 30-40 wt%; the main agent is selected from N-methyldiethanolamine or N, N-diethyl ethanolamine, the auxiliary agent is selected from piperazine or hydroxyethyl ethylenediamine, the accelerant A is selected from triethylene glycol monomethyl ether and / or ethylene glycol monomethyl ether, and the accelerant B is selected from ethyl butyl ether and / or isobutyl ether. The organic amine composite absorbent for carbon capture has a wide application prospect in removal of carbon dioxide in flue gas.

The invention relates to the technical field of conductive materials, in particular to a high-concentration dispersion system and a preparation method thereof. The high-concentration dispersion system comprises a conductive agent, a dispersing agent, a solvent and a viscosity reduction auxiliary agent, the conductive agent is modified carbon nanotubes, the dispersing agent is modified polyvinylpyrrolidone, the solvent is N-methyl pyrrolidone or deionized water, and the viscosity reduction auxiliary agent is piperazine anhydrous; wherein the modified carbon nano tube is obtained by mixing and heating a carbon nano tube and a mixed acid solution of nitric acid and sulfuric acid, then cooling, filtering, washing, drying, then dispersing in 75% ethanol, and finally adding 3-[3-carboxyl allylamido] propyltriethoxysilane for modification; the modified polyvinylpyrrolidone is obtained by heating polyvinylpyrrolidone at 310-330 DEG C and then oxidizing the polyvinylpyrrolidone. The conductive agent content of the high-concentration dispersion system is high, the conductive agent accounts for 15%-20% of the high-concentration dispersion system by mass, and the high-concentration dispersion system is low in viscosity, high in dispersity and good in conductivity.

The application discloses a specific palmitoyl transferase inhibitor and application thereof, and an active ingredient of the palmitoyl transferase inhibitor is 4-(3-(2-(trifluoromethyl)-9H-thioxanthene-9-ylidene)propyl)-1-piperazine ethanol or a salt thereof. Current palmitoylation inhibitors, 2-bromohexadecanoic acid (2-BP), cerulenin and tunicamycin can all inhibit protein palmitoylation in cells, but all are not selective. And the existing palmitoylation inhibitors are similar to endogenous fatty acids, and inevitably affect lipid metabolism in the body, which limits the clinical application. The application discloses, for the first time, the application of 4-(3-(2-(trifluoromethyl)-9H-thioxanthene-9-ylidene)propyl)-1-piperazine ethanol as a specific palmitoyl transferase inhibitor, and the palmitoyl transferase inhibitor is better in specificity and reversible in inhibition.

The invention relates to the technical field of membrane separation, in particular to a preparation method of a pH-step-by-step thermocuring regulation sodium-magnesium separation nanofiltration membrane. The method comprises the following steps: (1) pre-treating a base membrane; (2) preparation and treatment of an aqueous phase solution: S1, preparing the aqueous phase solution according to mass fraction: sequentially adding 1.2%-1.6% of piperazine, 0.10%-0.14% of triaminopyrimidine and 0.14%-0.18% of polyethylene glycol into deionized water, and stirring until the piperazine, the triaminopyrimidine and the polyethylene glycol are completely dissolved to form the aqueous phase solution; s2, adjusting the pH value of the water-phase solution to 10-11 by using hydrochloric acid; s3, pouring the water-phase solution of which the pH is adjusted on the surface of the pretreated base membrane, standing, and blow-drying to form a uniform water-phase layer; (3) interfacial polymerization reaction: S1, preparing an oil phase solution: adding 0.10-0.14% of trimesoyl chloride into n-hexane, and performing ultrasonic treatment until the trimesoyl chloride is completely dissolved; s2, pouring the oil-phase solution on the surface of the base membrane subjected to water-phase treatment, and after reaction, pouring out redundant solution to form a polyamide separation layer, so as to obtain a membrane sheet; (4) performing a step-by-step thermocuring process; and (5) cleaning and storing.

The present invention relates to combination therapy with (a) a mutant IDH inhibitor having the Formula I and (b) one or more of an antimetabolite agent, a hypomethylating agent, and a mutant Flt3 (Flt3) inhibitor, for the treatment of cancer.

Disclosed is a pharmaceutical composition for the treatment of tumors, the pharmaceutical composition comprising (6S, 9aS)-N-benzyl-8-({6-[3-(4-ethylpiperazin-1-yl) azetidin-1-yl] pyridin-2-yl} methyl)-6-(2-fluoro-4-hydroxybenzyl)-4, 7-dioxo-2-(propyl-2-en-1-yl) hexahydro-2H-pyrazino [2, 1-c] [1, 2, 3] triazolo [1, 2, 4] triazolo [1, 2, 4] triazolo [1, 2, 4] triazolo [1, 2, 4] triazolo [1, 2, 4] triazolo [1, 2, 4] triazolo [1, 2, 4] triazolo [1, 2, 4] triazolo [ The present invention relates to a compound of formula (I) or a pharmaceutically acceptable salt thereof and administered in combination with a MEK inhibitor.

The invention belongs to the technical field of membrane separation, and particularly relates to a method for preparing a high-flux hollow fiber nanofiltration membrane based on interfacial polymerization, the obtained membrane and application. The method comprises the following steps: firstly, carrying out pre-adsorption treatment on a polyethersulfone hollow fiber ultrafiltration base membrane through a polyethyleneimine aqueous solution to form a reactive anchoring layer; then sequentially dipping in an aqueous phase solution containing piperazine, sodium phytate and nanoscale cellulose whiskers and an organic phase solution containing trimesoyl chloride and 5-isocyanate isopeptide acyl chloride for interfacial polymerization; and finally, carrying out heat treatment on the obtained primary composite membrane, and completing a gas-phase cross-linking reaction in a glutaraldehyde steam atmosphere. According to the method, the hollow fiber nanofiltration membrane with high flux, high selectivity, excellent chlorine resistance and pollution resistance is successfully prepared through a multi-stage strengthening process, and the hollow fiber nanofiltration membrane is suitable for the fields of drinking water purification, industrial wastewater reuse, material separation and the like.

The invention belongs to the technical field of flame-retardant materials, and particularly relates to modified piperazine pyrophosphate, a composite flame retardant and a preparation method and application of the modified piperazine pyrophosphate and the composite flame retardant. The modified piperazine pyrophosphate provided by the invention is obtained by modifying piperazine pyrophosphate with a modifier; the modifier comprises silicon resin. According to the preparation method, the piperazine pyrophosphate is modified by adopting a specific type of silicon resin as a modifier, and the piperazine pyrophosphate is coated by utilizing a three-dimensional network structure of the silicon resin, so that the hydrophobicity and the flowability of the piperazine pyrophosphate powder can be improved, and the piperazine pyrophosphate powder has good dispersity in a high polymer material; and the paint has good flame retardance, water resistance, acid resistance and alkali resistance.

The invention discloses an environment-friendly halogen-free efficient flame-retardant composition, a flame retardant, a preparation method and application, and relates to the field of flame retardants, and the environment-friendly halogen-free efficient flame-retardant composition specifically comprises piperazine pyrophosphate, melamine cyanurate, organic phosphonate and polytetrafluoroethylene. The flame-retardant efficiency is improved. By introducing the silane coupling agent, the compatibility of the flame-retardant composition and polyolefin is improved, the processability of the flame retardant and a polyolefin substrate is improved, the precipitation of the flame retardant is reduced, and the flame-retardant composition can continuously and stably exist in a double-85 environment for more than 1000 hours without precipitation. The halogen-free flame retardant prepared by the method can reduce the use cost, solves the problem that most of the halogen-free flame retardants of the scorched piperidine system in the market are easy to separate out, is high in universality, and has a better flame-retardant effect in flame retardance of various types of polyolefins such as polypropylene and polyethylene.

The invention relates to a thermoplastic molding composition (P) comprising: (A) thermoplastic polymer composition (A) comprising: (A-1) 10 to 50 wt.-% of graft copolymer (A-1), (A-2) 1 to 50 wt.-%, of thermoplastic polymer matrix (A-2) based on one or more vinylaromatic copolymers, (A-3) 20 to 50 wt.-%, of polymerized alkyl methacrylate component (A-3), and (A-4) 0 to 45 wt.-% of comonomer which is copolymerized with the at least one polymerized alkyl methacrylate component (A-3), where the sum of (A-1), (A-2), (A-3) and optional comonomers (A-4) is 83.2 to 99.8 wt.-%; (B) a hindered amine light stabilizer composition (B), comprising at least two of substances (B-1) to (B-3): (B-1) 0 to 0.9 wt.-%, of at least one hindered amine light stabilizer having a dipiperidine structure with at least one alkyl group at each of the 2 and 6 positions of the dipiperidine structure (B-2) 0 to 0.9 wt.-%, of a hindered amine light stabilizer mixture having a monopiperidine structure with at least one alkyl group at each of the 2 and 6 positions of the monopiperidine structure, and (B-3) 0 to 2 wt.-%, of at least one hindered amine light stabilizer having a polymeric structure comprising piperidine groups with at least one alkyl group at each of the 2 and 6 positions of the piperidine groups (C) 0 to 5 wt.-%, of one or more further additives (C), different from (B); and (D) 0 to 10 wt.-%, of colorants, dyes and / or pigments (D), different from (C); wherein the constituents (A) to (D) sum up to 100 wt.-% of the molding composition (P).

The present disclosure provides crystalline and amorphous forms of 6-fluoro-7-(2-fluoro-6-hydroxyphenyl)-1-(4-methyl-2-(2-propanyl)-3-pyridinyl)-4-((2S)-2-methyl-4-(2-propenoyl)-1-piperazinyl)pyrido[2,3-d]pyrimidin-2 (1H)-one, including several anhydrous, hydrate and solvate forms, and solid state forms thereof, pharmaceutical compositions, and methods of treating a disease mediated by KRAS G12C inhibition.

The invention relates to the technical field of organic photoelectric materials, and particularly discloses a non-condensed ring small molecule acceptor material based on a quinonoid structure as well as a preparation method and application of the non-condensed ring small molecule acceptor material. According to the invention, easily available 1, 4-diacetyl piperazine-2, 5-diketone is used as a center, an alkyl chain and Ar are used for modification, EG is used as an end group, the non-condensed ring A-D-A '-D-A type structure acceptor material based on a quinone structure is constructed, and the general formula is shown in the specification. Wherein the PCE of the acceptor material which is modified by bithiophene and takes 2-(3-ethyl-4-oxothiazolidine-2-subunit) malononitrile as a terminal group reaches 15%. The non-condensed ring small molecule acceptor material based on the quinonoid structure is simple in synthesis process, and an effective strategy is provided for solving the problem of the overall performance of an organic solar cell.

The present disclosure provides crystalline and amorphous forms of 6-fluoro-7-(2-fluoro-6-hydroxyphenyl)-1-(4-methyl-2-(2-propanyl)-3-pyridinyl)-4-((2S)-2-methyl-4-(2-propenoyl)-1-piperazinyl)pyrido[2,3-d]pyrimidin-2(1H)-one, including several anhydrous, hydrate and solvate forms, and solid state forms thereof, pharmaceutical compositions, and methods of treating a disease mediated by KRAS G12C inhibition.

The invention provides an epoxy adhesive solution composition, a preparation method of an epoxy adhesive solution and a modified cellular board. The epoxy adhesive liquid composition comprises the following components in parts by weight: 53-58 parts of epoxy resin, 2-10 parts of a silane coupling agent, 1-10 parts of a curing agent, 1-5 parts of blocked isocyanate and 60-70 parts of water, wherein a blocking group of the blocked isocyanate is selected from hydroxyl, oximido, acylamino, amino, imidazolyl, pyrazolyl or piperazinyl. By introducing the blocked isocyanate with the specific structure, the epoxy adhesive liquid can be subjected to pre-crosslinking reaction in the early drying treatment process, the modulus and high temperature resistance of a formed dry film are improved, and the phenomenon of glue overflow in the subsequent curing stage is inhibited; therefore, the structural integrity and the bonding strength of the adhesive layer in the modified cellular board under the high-temperature condition are improved.

The invention discloses a method for preparing a solar cell by inhibiting perovskite iodine migration and modifying a thin film through a piperazine derivative, and belongs to the technical field of perovskite solar cells. According to the method, a piperazine derivative is used between a perovskite layer and an electron transport layer, so that the piperazine derivative has the functions of modifying a perovskite thin film and inhibiting iodine migration. A modified perovskite light absorption layer is obtained by spin-coating a piperazine derivative solution on the surface of perovskite. The piperazine derivative can act with the iodine simple substance generated after the perovskite material is degraded, and decomposes the iodine simple substance to generate iodide ions, so that further degradation of the perovskite film is prevented, contact between the iodine simple substance and a silver electrode is reduced, and the stability of perovskite is improved. Meanwhile, the material can effectively passivate lead site defects on the surface of the perovskite thin film, and non-radiative recombination generated at the defects is reduced. According to the method, perovskite degradation and silver electrode damage caused by iodine elementary substance volatilization can be effectively inhibited, and an efficient and stable perovskite solar cell device is finally obtained.

The invention provides a Lewis acid metal ion-piperazine modified nanocellulose film as well as a preparation method and application thereof, and belongs to the technical field of battery materials. The preparation method comprises the following steps: mixing carboxylated nanocellulose with Lewis acidic metal salt in a solution, and carrying out pre-crosslinking reaction to obtain Lewis acidic metal ion modified carboxylated nanocellulose; a piperazine ligand compound and dopamine hydrochloride are added into the Lewis acidic metal ion modified carboxylated nano-cellulose, a cross-linking reaction is carried out with Lewis acidic metal ions as the center, suction filtration is carried out, and a film is formed. The metal in the Lewis acid metal salt is metal cations with the valence of more than bivalent. The carboxylated nanocellulose, the Lewis acid metal ion-piperazine complex and the solid polymer electrolyte are organically combined together for the first time and are applied to the lithium metal battery, the unique advantages of the lithium metal battery in the field of batteries are shown, and the rate capability and the cycling stability are greatly improved.

The invention discloses a flame-retardant cotton fiber and a preparation method thereof, and relates to the field of cotton fibers. When the flame-retardant cotton fiber is prepared, dicarboxyl phenyl porphyrin and copper nitrate react to prepare a metal organic framework nanosheet; the preparation method comprises the following steps: reacting 2, 4, 6-tri (4-formyl phenyl)-1, 3, 5-triazine, 2-aminomethyl piperazine and phosphorous acid to prepare a flame-retardant graft; the cotton balls, the metal organic framework nanosheets and the flame-retardant graft react to prepare pre-modified cotton fibers; and carrying out ring-opening reaction on the pre-modified cotton fiber and epoxy chloropropane, and then carrying out ring-closing to obtain the flame-retardant cotton fiber. The flame-retardant cotton fiber prepared by the invention has excellent antibacterial property, flame retardance, color fixation and dispersity.

The invention relates to a reverse osmosis membrane and a preparation method thereof, and the preparation method comprises the following steps: immersing a polysulfone-based membrane into a dopamine-containing mixed solution, and carrying out constant-temperature oscillation to form a dopamine pretreatment layer so as to obtain a modified base membrane; dissolving rosmarinic acid ester modified m-phenylenediamine, piperazine, a surfactant, an auxiliary agent and a pH regulator in water, and stirring for dissolving to obtain a water phase solution; dissolving an acyl chloride monomer in an organic solvent, stirring and dissolving, then adding the modified titanium dioxide, and carrying out ultrasonic dispersion to obtain an oil phase solution; immersing the modified base membrane into the water phase solution, taking out the modified base membrane, immersing the modified base membrane into the oil phase solution, taking out the modified base membrane and drying the modified base membrane to obtain a pre-compounded reverse osmosis membrane; and carrying out post-treatment on the pre-compounded reverse osmosis membrane to obtain the reverse osmosis membrane. Under the condition that the water yield is guaranteed, the reverse osmosis membrane disclosed by the invention has a high desalination rate and the oxidation resistance of the reverse osmosis membrane is improved for a long time.

Methods for treating patients with wAIHA comprising administering at least one compound chosen from (R)-2-[3-[4-amino-3-(2-fluoro-4-phenoxy-phenyl)pyrazolo[3,4-d]pyrimidin-1-yl]piperidine-1-carbonyl]-4-methyl-4-[4-(oxetan-3-yl)piperazin-1-yl]pent-2-enenitrile (rilzabrutinib) and pharmaceutically acceptable salts thereof are disclosed.

A method for reducing a substrate selected from 2-methyl-5-nitropyridine and methyl 4-(2-fluoro-3-nitrobenzyl)piperazine-1-carboxylate is provided catalysed by a nitroreductase and a disproportionation agent.

The invention relates to the technical field of flame-retardant high polymer materials, in particular to a high-temperature-resistant and high-humidity-resistant flame-retardant polypropylene composite material and a preparation method thereof. The invention provides a high-temperature-resistant and high-humidity-resistant flame-retardant polypropylene composite material. The high-temperature-resistant and high-humidity-resistant flame-retardant polypropylene composite material consists of polypropylene, a mixed silane modified intumescent flame retardant, a flame-retardant aid NOR 116 and a compatilizer According to the invention, bis [3-(trimethoxysilyl) propyl] amine / triacetoxyvinyl silane is mixed to modify an intumescent flame retardant, which is composed of piperazine pyrophosphate as a main flame retardant and melamine polyphosphate, aluminum hypophosphite or aluminum diethylphosphinate as a secondary flame retardant; a plurality of active silicon hydroxyl sites after silane hydrolysis are mixed, and single flame retardants are connected together to form a macromolecular intumescent flame retardant, so that the modified intumescent flame retardant is still difficult to migrate or separate out from a polypropylene matrix even under high-temperature and high-humidity conditions, and the weather resistance of flame-retardant polypropylene is greatly improved.

The invention relates to the technical field of sewage treatment in environmental protection, in particular to a high-valence metal cation composite remover and a use method of the high-valence metal cation composite remover. The polyhydroxy compound, the polycarboxyl compound and the polyamido compound are one or more than two of dithiomethyl carbamate, dithioethyl carbamate, dithiopiperazine dicarboxylate, trithiocyanate, hyperbranched vinylamine dithiocarbamate and dodecyl sulfonate, and the polyhydroxy compound, the polycarboxyl compound and the polyamido compound are one or more than two of dithiomethyl carbamate, dithioethyl carbamate, dithiopiperazine dicarboxylate, trithiocyanate, hyperbranched vinylamine dithiocarbamate and dodecyl sulfonate; the inorganic matter is one or more than two of silicate, phosphate and carbonate. According to the method, after the ammonia water is added, the composite removing agent is added for reaction and precipitation, the method has the advantages that the technological process is simple, the agent adding amount is small, the removal rate of high-valence metal cations reaches 99.9% or above, the operation cost is low, the pH value in the process is low, ammonia volatilization waste is inhibited and controlled, and the problems of safety and environmental protection are solved, and the method is suitable for industrial production.

The invention discloses a passivation molecule, the passivation molecule is N-acetyl piperazine halide and N-formyl piperazine halide, the two ends of the passivation molecule respectively contain ammonium cations and carbonyl functional groups, and the passivation molecule shows stable plane orientation preference due to the double-site geometric synergistic anchoring effect of'ammonium-carbonyl '. Therefore, synchronous passivation of double defects can be realized on the surface of the perovskite, and the photoelectric conversion efficiency and the stability of the perovskite solar cell can be improved.

A method for preparing a composite nanofiltration membrane based on aspartic acid modified carbon quantum dots belongs to the field of nanofiltration membrane preparation, and comprises the following steps: 1) dissolving citric acid monohydrate in water, adding aspartic acid, heating and stirring, and then adding a sodium hydroxide solution to adjust pH; (2) carrying out suction filtration on the mixed solution obtained in the step (1) by using a microfiltration membrane, dialyzing and purifying in ultrapure water, and freeze-drying to obtain the aspartic acid modified carbon quantum dots; (3) fixing a polysulfone base membrane in a mold, preparing a water-phase solution containing anhydrous piperazine and aspartic acid modified carbon quantum dots, pouring the water-phase solution into the mold to be in contact with the base membrane, and air-drying; and 4) preparing a trimesoyl chloride solution by using n-hexane as a solvent, pouring the trimesoyl chloride solution into a mold for contact, and finally drying to obtain the composite nanofiltration membrane.When the concentration of the aspartic acid modified carbon quantum dots is 2000ppm, the water flux reaches 168LMH, the retention rate reaches a peak value when the concentration of the quantum dots is 1000ppm and is 1.3 times of that of a base membrane, and the composite nanofiltration membrane shows excellent performance.

The invention provides epoxy resin for halogen-free flame-retardant self-leveling powder coating and a preparation method of the epoxy resin, and belongs to the technical field of powder coating. The flame retardant is mainly prepared from anhydrous piperazine, bisphenol A diglycidyl ether, trihydroxymethyl phosphorus oxide, triethyl phosphite, epoxy chloropropane, sodium hydroxide, N-methyl iminodiacetic acid, ethylene glycol diglycidyl ether and other main raw materials through polymerization. The prepared epoxy resin and 2-phenylimidazoline are subjected to low-temperature curing (135 DEG C / 20 min) on the premise that an additional flatting agent does not need to be used, the flexibility of a coating film is good, the impact resistance grade is high, the impact performance reaches the condition that no cracking phenomenon exists in the front and back 60cm, the leveling grade reaches the grade 7 or above, the gloss is high and reaches 95% or above, the oxygen index reaches 34% or above, and the halogen-free flame retardant performance is excellent.

The invention relates to an acid-resistant nanofiltration membrane and a preparation method thereof, and relates to the technical field of nanofiltration membranes. The acid-resistant nanofiltration membrane comprises a supporting base layer and a functional layer, the functional layer is formed by interfacial polymerization on the supporting base layer, the supporting base layer comprises a polyetherimide-nanomembrane, raw materials of the functional layer comprise an oil-phase solution and a water-phase solution, the oil-phase solution comprises 1, 3, 5-benzene trisulfonyl chloride and an oil-phase solvent, and the water-phase solution comprises 1, 3, 5-benzene trisulfonyl chloride and a water-phase solvent. The water-phase solution comprises piperazine and a water-phase solvent; the method has the effect of improving the acid resistance of the nanofiltration membrane.

The invention provides solvent-resistant polyurethane resin, which is prepared from the following substances in parts by mass: 60 to 90 parts of diol, 15 to 25 parts of diisocyanate, 3 to 8 parts of auxiliaries, 1.5 to 3 parts of 1, 4-bis (2-hydroxyethyl) piperazine, 2 to 4 parts of 2, 2-dimethylolpropionic acid, 0.5 to 2 parts of catalysts, 0 to 3 parts of 4, 4 '-dithiodibenzoic acid diglycidyl ester and 0 to 2 parts of sodium alginate. Meanwhile, the invention further provides a simple preparation method, and the prepared solvent-resistant polyurethane resin is low in soaking swelling rate, good in solvent resistance, high in tensile strength and simple in preparation process and can be applied to the industries such as chemical anticorrosive paint, printing ink and electronic packaging.

The invention relates to the technical field of polyamide nanofiltration membranes, in particular to an acid and alkali resistant high-strength nanofiltration membrane and a preparation method thereof. The problem that the strength and the acid and alkali resistance of a polyamide nanofiltration membrane in the prior art cannot be considered at the same time is solved. The base membrane material of the polyamide nanofiltration membrane is modified polyethersulfone and is obtained by chemically bonding a carbon nanotube subjected to double surface modification by titanium dioxide sol-gel and a KH550 coupling agent in a polyester non-woven fabric, and the modulus of the material is improved by utilizing an inorganic-organic hybrid network; the functional layer of the polyamide nanofiltration membrane is made of modified polyamide, and the modified polyamide functional layer is formed by forming a polyamide matrix through polymerization reaction of 2, 2 '-disulfonic acid-4, 4'-diaminobiphenyl, piperazine and trimesoyl chloride and introducing 4-amino-2, 2, 6, 7-tetramethyl-1, 3-pentanediol at the same time. And the chemical resistance is improved by a free radical capturing group generated by 2, 2, 6, 6-tetramethylpiperidine and octa-isobutyl cage type silsesquioxane.

The invention discloses a preparation method and application of a monovalent cation selective membrane for efficient lithium-magnesium separation, and belongs to the technical field of preparation of cation selective membranes. The monovalent cation selective membrane is composed of a polyamide nanofiltration base membrane and a polyethyleneimine positive electricity layer, and the preparation method comprises the following steps: taking piperazine anhydrous as a water phase concentration and trimesoyl chloride as an oil phase monomer, reacting on a polyethersulfone ultrafiltration base membrane, and preparing the polyamide nanofiltration base membrane by utilizing an interfacial polymerization method; and anchoring on the surface of the polyamide nanofiltration base membrane by utilizing cross-linking of gallic acid and PEI with the molecular weight of about 70000 through a multi-layer deposition method to obtain the Gallic-PEI / polyamide composite membrane with the positively charged surface. The membrane can realize lithium-magnesium separation through pore size screening and electrostatic repulsion effect, and has high lithium-magnesium selectivity while maintaining large lithium ion flux in the application process of an electrodialysis system, so that the lithium-magnesium separation effect of salt lake brine is improved.