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KR-20260064728-A - Positively charged acid- and alkali-resistant composite nanofiltration membrane, method of manufacturing the same, and applications

KR20260064728AKR 20260064728 AKR20260064728 AKR 20260064728AKR-20260064728-A

Abstract

This disclosure relates to the field of membranes and discloses a positively charged acid- and alkali-resistant composite nanofiltration membrane, a method for manufacturing the same, and applications. The positively charged acid- and alkali-resistant composite nanofiltration membrane sequentially comprises a bottom layer, a porous intermediate layer, and an acid- and alkali-resistant separation layer; the acid- and alkali-resistant separation layer comprises (1) a quaternary ammonium base represented by Formula (I) and/or a quaternary phosphonium base represented by Formula II by grafting the acid- and alkali-resistant separation layer through (1) N atoms; Equation (I); Formula (II); where R1 is a substituted or unsubstituted C1-C9 alkylene or phenylene group; R2 , R3 , R4 are each independently selected from a C1-C3 alkyl group or a phenyl group; R5 is a C1-C6 alkylene group, a phenylene group, or a C7-C10 arylalkylene group; R6 , R7 , R8 are each independently a phenyl group or a C7-C10 arylalkyl group; and X is a halogen; or (2) A quaternary ammonium salt structure comprising the structural formula represented by Formula (III) and/or the structure represented by Formula (IV); and Equation (III); Formula (IV); X is a halogen, n is an integer from 0 to 10; m is an integer from 2 to 10; where, the acid-resistant and alkali-resistant separation layer is selected from at least one of a polyurea separation layer, a polytriazineamine separation layer, a polysulfonamide separation layer, a poly(triazineamine-urea) separation layer, a poly(sulfonamide-urea) separation layer, a poly(triazineamine-sulfonamide) separation layer, and a poly(triazineamine-sulfonamide-urea) separation layer. The nanofiltration membrane maintains a high permeation flow rate while having a high metal exclusion rate.

Inventors

  • 우 창장
  • 중 티안
  • 자오 궈커
  • 장 양
  • 류 이춘
  • 판 궈위안
  • 탕 궁칭
  • 위 하오
  • 자오 무후아
  • 리 위

Assignees

  • 차이나 페트로리움 앤드 케미컬 코포레이션
  • 시노펙 (베이징) 리서치 인스티튜트 오브 케미컬 인더스트리 컴퍼니 리미티드

Dates

Publication Date
20260507
Application Date
20240905
Priority Date
20230905

Claims (20)

  1. In a positively charged acid-resistant and alkali-resistant composite nanofiltration membrane, The above-mentioned positively charged acid- and alkali-resistant composite nanofiltration membrane sequentially comprises a lower layer, a porous intermediate layer, and an acid- and alkali-resistant separation layer; The above acid-resistant and alkali-resistant separation layer is, (1) A quaternary ammonium base represented by formula (I) and/or a quaternary phosphonium base represented by formula (II) grafted onto the acid-resistant and alkali-resistant separation layer through N atoms; Equation (I); Formula (II); Here, R1 is a substituted or unsubstituted C1-C9 alkylene or phenylene group; R2 , R3 , and R4 are each independently selected from a C1-C3 alkyl group or a phenyl group; R5 is a C1-C6 alkylene group, a phenylene group, or a C7-C10 arylalkylene group; R6 , R7 , and R8 are each independently a phenyl group or a C7-C10 arylalkyl group; X is a halogen; or (2) A quaternary ammonium salt structure comprising a structural formula represented by formula (III) and/or a structural formula represented by formula (IV); and Equation (III); Formula (IV); X is a halogen, n is an integer from 0 to 10; m is an integer from 2 to 10; Herein, the acid-resistant and alkali-resistant separation layer is a positively charged acid-resistant and alkali-resistant composite nanofiltration membrane selected from at least one of a polyurea separation layer, a polytriazineamine separation layer, a polysulfonamide separation layer, a poly(triazineamine-urea) separation layer, a poly(sulfonamide-urea) separation layer, a poly(triazineamine-sulfonamide) separation layer, and a poly(triazineamine-sulfonamide-urea) separation layer.
  2. In paragraph 1, (1) In case, R1 is a C1-C9 substituted or unsubstituted alkylene or phenylene group, and the substituent is a carboxyl group, nitro group, amino group, silyl group, carbonyl group, ether group, or ester group; preferably, R1 is a C1-C9 unsubstituted alkylene or phenylene group; preferably, R1 is a C1-C6 unsubstituted alkylene or phenylene group; preferably, R1 is a C1-C3 unsubstituted alkylene group; and/or R2 , R3 , and R4 are each independently selected from C1-C3 alkyl groups; Preferably, R2 , R3 , and R4 are each independently CH3 ; and/or R5 is a C1-C3 alkylene group, a phenylene group, or a C8-C10 arylalkylene group; Preferably, R5 is a C1-C3 alkylene group or a C8-C10 arylalkylene group; and/or R6 , R7 , and R8 are each independently a phenyl group or a C8-C10 arylalkyl group; Preferably, R6 , R7 , and R8 are each independently a phenyl group; and/or, A positively charged acid- and alkali-resistant composite nanofiltration membrane, where X is Cl, Br, or I.
  3. In paragraph 1, (2) In case, X is Cl, Br, or I; and/or n is an integer from 0 to 7; and/or A positively charged acid- and alkali-resistant composite nanofiltration membrane, where m is an integer from 2 to 8.
  4. In any one of paragraphs 1 through 3, The above acid-resistant and alkali-resistant separation layer is a positively charged acid-resistant and alkali-resistant composite nanofiltration membrane selected from at least one of a polyurea separation layer, a polytriazine amine separation layer, and a polysulfonamide separation layer.
  5. In any one of paragraphs 1 through 4, The content of nitrogen atoms in the structure of the quaternary ammonium base or quaternary ammonium salt in the above-mentioned positively charged acid-resistant and alkali-resistant composite nanofiltration membrane is 0.5-20 at.%, preferably 2-15 at.%; and/or A positively charged acid-resistant and alkali-resistant composite nanofiltration membrane, wherein the content of phosphorus atoms in the quaternary phosphonium base among the above positively charged acid-resistant and alkali-resistant composite nanofiltration membranes is 0.4-3 at.%, preferably 0.5-2 at.%.
  6. In any one of paragraphs 1 through 5, (1) In the case of the positively charged acid-resistant and alkali-resistant composite nanofiltration membrane, the content of nitrogen atoms in the quaternary ammonium base is 10-20 at.% or 10-15 at.%; or In the case of (1), the content of nitrogen atoms in the quaternary ammonium base of the positively charged acid-resistant and alkali-resistant composite nanofiltration membrane is 0.5-6 at.% or 2-5 at.%; and/or (2) In the case of the positively charged acid-resistant and alkali-resistant composite nanofiltration membrane, the content of nitrogen atoms in the quaternary ammonium salt structure of the positively charged acid-resistant and alkali-resistant composite nanofiltration membrane is 0.5-5 at.%, preferably 2-5 at.%.
  7. In any one of paragraphs 1 through 6, A positively charged acid-resistant and alkali-resistant composite nanofiltration membrane having a surface Zeta potential of 0-30 mV, preferably 5-25 mV, and preferably 5-20 mV.
  8. In any one of paragraphs 1 through 7, The positively charged acid-resistant and alkali-resistant composite nanofiltration membrane has an average pore diameter of 0.1-0.5 nm, preferably 0.1-0.4 nm, preferably 0.15-0.3 nm, and preferably 0.2-0.3 nm.
  9. In any one of paragraphs 1 through 8, A positively charged acid-resistant and alkali-resistant composite nanofiltration membrane having a contact angle of 20-80°, preferably 30-80°, and preferably 30-60°.
  10. In any one of paragraphs 1 through 9, The thickness of the above lower layer is 30-150 µm, preferably 50-120 µm; and/or The thickness of the porous support layer is 10-100 µm, preferably 30-60 µm; and/or A positively charged acid- and alkali-resistant composite nanofiltration membrane, wherein the thickness of the acid- and alkali-resistant separation layer is 10-500 nm, preferably 50-300 nm.
  11. A method for manufacturing a positively charged acid- and alkali-resistant composite nanofiltration membrane, The above manufacturing method is, (S1) A step of adding a first solution containing a catalyst, a quaternary ammonium halide and/or a quaternary phosphonium halide, to a second solution containing polyamine under stirring conditions to react and obtain a modified polyamine; (S2) A step of manufacturing a porous support layer on the lower layer; (S3) A step of first contacting the surface of a porous support layer with an aqueous phase containing the modified polyamine of step (S1), then second contacting it with an organic phase containing a polyfunctional polar monomer, and then subjecting it to heat treatment to obtain the positively charged acid-resistant and alkali-resistant composite nanofiltration membrane; comprising The above quaternary ammonium halide salt has a structure represented by formula (I), and the above quaternary phosphonium halide salt has a structure represented by formula (2); Equation (I); Equation (2); Here, R1' is a substituted or unsubstituted C1-C9 alkylene or phenylene group; R2 ', R3 ', and R4 ' are each independently selected from a C1-C3 alkyl group or a phenyl group; R5 ' is a C1-C6 alkylene group, a phenylene group, or a C7-C10 arylalkylene group; and R6 ', R7 ', and R8 ' are each independently a phenyl group or a C7-C10 arylalkyl group; A method for manufacturing a positively charged acid-resistant and alkali-resistant composite nanofiltration membrane, wherein X and X1 are each independently halogens.
  12. A method for manufacturing a positively charged acid- and alkali-resistant composite nanofiltration membrane, The above method is, (S1') A step of obtaining a composite membrane by sequentially manufacturing a porous support layer and an acid-resistant and alkali-resistant separation layer on a lower layer; (S2') A step of contacting the composite membrane with an aqueous solution containing a catalyst, a quaternary ammonium halide and/or a quaternary phosphonium halide, and drying to obtain the positively charged acid-resistant and alkali-resistant composite nanofiltration membrane; The above quaternary ammonium halide salt has a structure represented by formula (I), and the above quaternary phosphonium halide salt has a structure represented by formula (2); Equation (I); Equation (2); Here, R1' is a substituted or unsubstituted C1-C9 alkylene or phenylene group; R2 ', R3 ', and R4 ' are each independently selected from C1-C3 alkyl groups or phenyl groups; and R5 ' is a C1-C6 alkylene group, phenylene group, or C7-C10 arylalkylene group; R6 ', R7 ', and R8 ' are each independently a phenyl group or a C7-C10 arylalkyl group; A method for manufacturing a positively charged acid-resistant and alkali-resistant composite nanofiltration membrane, wherein X and X1 are each independently halogens.
  13. In Article 11 or Article 12, R1 ' is a C1-C9 substituted or unsubstituted alkylene or phenylene group, and the substituent is a hydroxyl group, carboxyl group, nitro group, amino group, silyl group, carbonyl group, ether group, or ester group; preferably, R1 ' is a C1-C9 unsubstituted alkylene or phenylene group; preferably, R1 ' is a C1-C6 unsubstituted alkylene or phenylene group; preferably, R1 ' is a C1-C3 unsubstituted alkylene group; and/or R2 ', R3 ', and R4 ' are each independently selected from C1-C3 alkyl groups; preferably, R2 ', R3 ', and R4 ' are each independently CH3 ; and/or R 5 ' is a C1-C3 alkylene group, a phenylene group, or a C8-C10 arylalkylene group; preferably, R 5 ' is a C1-C3 alkylene group or a C8-C10 arylalkylene group; R6 ', R7 ', and R8 ' are each independently a phenyl group or a C8-C10 arylalkyl group; preferably, R6 ', R7 ', and R8 ' are each independently a phenyl group; and/or X is Cl, Br, or I; and/or A method for preparing a positively charged acid- and alkali-resistant composite nanofiltration membrane, wherein X 1 is F, Cl, Br, or I.
  14. In any one of paragraphs 11 through 13, The above quaternary ammonium halides are 2-chloroethyltrimethylammonium chloride, 2-chloroethyltriethylammonium chloride, 2-chloroethyltriphenylammonium chloride, 3-chloro-2-hydroxypropyltrimethylammonium chloride, 3-chloropropyltrimethylammonium chloride, 4-chlorobutyltrimethylammonium chloride, 5-chloropentyltrimethylammonium chloride, 6-chlorohexyltrimethylammonium chloride, 2-bromoethyltrimethylammonium bromide, 3-bromopropyltrimethylammonium bromide, 4-bromobutyltrimethylammonium bromide, 5-bromopentyltrimethylammonium bromide, 6-bromohexyltrimethylammonium bromide, iodomethyltrimethylammonium iodide, and 2-iodoethyltrimethylammonium At least one selected from iodide, 3-iodopropyltrimethylammonium iodide, 4-iodobutyltrimethylammonium iodide, 5-iodopentyltrimethylammonium iodide, and 6-iodohexyltrimethylammonium iodide; preferably 2-chloroethyltrimethylchloride and/or 3-bromopropyltrimethylammonium; and/or The above quaternary phosphonium halides are 3-bromopropyltriphenylphosphonium bromide, 2-bromoethyltriphenylphosphonium bromide, 1-bromoethyltriphenylphosphonium bromide, bromomethyltriphenylphosphonium bromide, 3-chloropropyltriphenylphosphonium chloride, 2-chloroethyltriphenylphosphonium chloride, 1-chloroethyltriphenylphosphonium chloride, chloromethyltriphenylphosphonium chloride, 3-iodopropyltriphenylphosphonium iodide, 2-iodoethyltriphenylphosphonium iodide, 1-iodoethyltriphenylphosphonium iodide, iodomethyltriphenylphosphonium bromide, 4-bromomethylbenzyltriphenylphosphonium bromide, 2-bromomethylbenzyltriphenylphosphonium bromide, 3-bromomethylbenzyltriphenylphosphonium bromide, At least one selected from 4-chloromethylbenzyltriphenylphosphonium chloride, 2-chloromethylbenzyltriphenylphosphonium chloride, 3-chloromethylbenzyltriphenylphosphonium chloride, 4-iodomethylbenzyltriphenylphosphonium iodide, 2-iodomethylbenzyltriphenylphosphonium iodide, and 3-iodomethylbenzyltriphenylphosphonium iodide, preferably 3-bromopropyltriphenylphosphonium bromide and/or 4-bromomethylbenzyltriphenylphosphonium bromide; and/or A method for preparing a positively charged acid- and alkali-resistant composite nanofiltration membrane, wherein the catalyst is at least one selected from sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium bicarbonate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate, preferably potassium hydroxide.
  15. In Paragraph 12, Step (S1') is, (S1-1') A step of manufacturing a porous support layer on a lower layer; and (S1-2') A method for manufacturing a positively charged acid- and alkali-resistant composite nanofiltration membrane, comprising the step of first contacting the surface of a porous support layer with a polyamine-containing aqueous phase, then secondarily contacting it with an organic phase containing a polyfunctional polar monomer, and heat treating it to obtain a composite membrane.
  16. In either paragraph 11 or paragraph 15, The above polyamine is at least one selected from polyethyleneimine, polyvinylamine, triethylenetetramine, tetraethylenepentamine, diethylenetriamine, polyethylenepolyamine, piperazine, m-phenylenediamine, and p-phenylenediamine; Preferably polyethyleneimine and/or polyethylenepolyamine; and/or The above-mentioned polyfunctional polar monomer is at least one selected from polyisocyanates, triazine compounds containing at least two C-Cl bonds, and polysulfonyl chlorides; Preferably, the polyisocyanate is at least one selected from m-xylylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, toluene-2,6-diisocyanate, 1,4-phenylene diisocyanate, toluene-2,4-diisocyanate, 4,4'-methylene bis(phenyl isocyanate), 1,3-phenylene diisocyanate, 3,3'-dichloro-4,4'-biphenyl diisocyanate biphenyl, dicyclohexylmethane-4,4'-diisocyanate, trimethylhexamethylene diisocyanate, L-lysine ethyl ester diisocyanate, 1,4-cyclohexyl diisocyanate, and 4-chloro-6-methyl-m-phenylene diisocyanate; Preferably 1,4-phenylene diisocyanate and/or 1,3-pyrenyl diisocyanate; and/or Preferably, the triazine compound comprising at least two C-Cl bonds is at least one selected from cyanuric chloride, 2,4-dichloro-1,3,5-triazine, 2,5-dichloro-1,3,5-triazine, and 2,4-dichloro-6-phenyl-1,3,5-triazine; preferably, it is cyanuric chloride; Preferably, the polysulfonyl chloride is at least one selected from 1,3-benzenedisulfonyl chloride, 1,2-benzenedisulfonyl chloride, 1,4-benzenedisulfonyl chloride, 2,4-disulfonyl chloride mesitylene, biphenyl-4,4'-disulfonyl chloride, 4,5-dichloro-1,3-benzenedisulfonyl chloride, 2,6-naphthalenedisulfonyl chloride, 1,3-naphthalenedisulfonyl chloride, 2,7-naphthalenedisulfonyl chloride, 1,3,5-benzenetrisulfonyl chloride, and 1,3,6-naphthalenedisulfonyl chloride; preferably 1,3-benzenedisulfonyl chloride, a method for preparing a positively charged acid- and alkali-resistant composite nanofiltration membrane.
  17. In either of paragraphs 14 and 16, In step (S1), The concentration of the quaternary ammonium halide and/or quaternary phosphonium salt in the first solution is 0.5 wt%-20 wt%, preferably 1 wt%-10 wt%; and/or The concentration of the catalyst in the first solution is 0.01wt%-5wt%, preferably 0.1wt%-1wt%; and/or The concentration of polyamine in the second solution is 1 wt%-20 wt%, preferably 5 wt%-10 wt%; and/or The amounts of the first solution and the second solution used are such that the mass ratio of the polyamine, the quaternary ammonium halide and/or quaternary phosphonium salt, and the catalyst is 1-1000:1-100:1, preferably 1-200:1-50:1; and/or The above reaction conditions include a reaction temperature of 25-90°C, preferably 40-60°C; a reaction time of 1-48h, preferably 6-24h; and/or In step (S3), The concentration of the modified polyamine in the above aqueous phase is 0.1 wt%-10 wt%, preferably 0.5 wt%-2.5 wt%; and/or The concentration of the polyfunctional polar monomer in the above organic phase is 0.01 wt%-2 wt%, preferably 0.05-1 wt%; and/or The first contact time is 5-100s, preferably 10-60s; and/or The second contact time is 10-200s, preferably 20-120s; and/or A method for manufacturing a positively charged acid- and alkali-resistant composite nanofiltration membrane, wherein the heat treatment conditions include a heat treatment temperature of 40-150°C, preferably 50-120°C; and a heat treatment time of 0.5-10 min, preferably 1-5 min.
  18. In any one of paragraphs 12 through 16, In step (S2'), the contact method is immersion; and/or The above contact time is 10s-10min, preferably 20s-1min; The above contact temperature is 20-80℃, preferably 30-50℃; and/or The above drying time is 0.5-10 min, preferably 3-5 min; The above drying temperature is 40-80℃, preferably 50-70℃; and/or The concentration of the catalyst in the above aqueous solution is 0.01 wt%-5 wt%, preferably 0.1 wt%-1 wt%; and/or A method for preparing a positively charged acid- and alkali-resistant composite nanofiltration membrane, wherein the concentration of the quaternary ammonium halide and/or quaternary phosphonium salt in the above aqueous solution is 1 wt%-20 wt%, preferably 5 wt%-10 wt%.
  19. A method for manufacturing a positively charged acid- and alkali-resistant composite nanofiltration membrane, The above manufacturing method is, (S1'') Step of manufacturing a porous support layer on the lower layer; (S2'') A step of sequentially contacting the membrane layer obtained in step (S1') with an aqueous phase of a polyamine containing a tertiary amine group for the first contact, contacting it with an organic phase containing a polyfunctional polar monomer for the second contact, and after heat treatment, obtaining a composite nanofiltration membrane of an acid-resistant and alkali-resistant separation layer; (S3'') A step of obtaining a positively charged acid-resistant and alkali-resistant composite nanofiltration membrane by contacting the composite nanofiltration membrane with a halogenated alkane and a catalyst-containing organic solution for a third time, and then drying; comprising a method for manufacturing a positively charged acid-resistant and alkali-resistant composite nanofiltration membrane.
  20. In Paragraph 19, In step (S2''), the tertiary amine group-containing polyamine is at least one selected from polyethyleneimine, polyethylenepolyamine, 1-aminopiperazine, 1,4-diaminopiperazine, 1,4-piperazine diethylamine, and 1,4-bis(aminopropyl)piperazine, preferably polyethyleneimine and/or polyethylenepolyamine; and/or In the aqueous phase of the above tertiary amine group-containing polyamine, the concentration of the tertiary amine group-containing polyamine is 0.1 wt%-10 wt%, preferably 0.5 wt%-2.5 wt%; and/or The above-mentioned polyfunctional polar monomer is at least one selected from polyisocyanates, triazine compounds comprising at least two C-Cl bonds, and polysulfonyl chlorides; Preferably, the polyisocyanate is at least one selected from m-xylylene diisocyanate, isophorone diisocyanate, 1,6-hexamethylene diisocyanate, toluene-2,6-diisocyanate, 1,4-phenylene diisocyanate, toluene-2,4-diisocyanate, 4,4'-methylene bis(phenyl isocyanate), 1,3-phenylene diisocyanate, 3,3'-dichloro-4,4'-diisocyanate biphenyl, dicyclohexylmethane-4,4'-diisocyanate, trimethylhexamethylene diisocyanate, L-lysine ethyl ester diisocyanate, 1,4-cyclohexyl diisocyanate, and 4-chloro-6-methyl-m-phenylene diisocyanate; Preferably 1,4-phenylene diisocyanate and/or 1,3-phenylene diisocyanate; Preferably, the triazine compound comprising at least two C-Cl bonds is at least one selected from cyanuric chloride, 2,4-dichloro-1,3,5-triazine, 2,5-dichloro-1,3,5-triazine, and 2,4-dichloro-6-phenyl-1,3,5-triazine; preferably, it is cyanuric chloride; Preferably, the polysulfonyl chloride is at least one selected from 1,3-benzenedisulfonyl chloride, 1,2-benzenedisulfonyl chloride, 1,4-benzenedisulfonyl chloride, 2,4-disulfonyl chloride mesitylene, biphenyl-4,4'-disulfonyl chloride, 4,5-dichloro-1,3-benzenedisulfonyl chloride, 2,6-naphthalenedisulfonyl chloride, 1,3-naphthalenedisulfonyl chloride, 2,7-naphthalenedisulfonyl chloride, 1,3,5-benzenetrisulfonyl chloride, and 1,3,6-naphthalenedisulfonyl chloride; preferably, it is 1,3-benzenedisulfonyl chloride; and/or In the above organic phase, the concentration of the polyfunctional polar monomer is 0.01 wt%-2 wt%, preferably 0.05-1 wt%; and/or The amounts of the aqueous phase of the tertiary amine group-containing polyamine and the organic phase containing the polyfunctional polar monomer used are such that the weight ratio of the tertiary amine group-containing polyamine to the polyfunctional polar monomer is 2-200:1, preferably 5-80:1; and/or The first contact time is 5-100s, preferably 10-60s; and/or The second contact time is 10-200s, preferably 20-120s; and/or A method for manufacturing a positively charged acid- and alkali-resistant composite nanofiltration membrane, wherein the heat treatment conditions include a heat treatment temperature of 40-150°C, preferably 50-120°C; and a heat treatment time of 0.5-10 min, preferably 1-5 min.

Description

Positively charged acid- and alkali-resistant composite nanofiltration membrane, method of manufacturing the same, and applications The present invention relates to the field of membranes, and in particular to a positively charged, acid- and alkali-resistant composite nanofiltration membrane and a method for manufacturing the same and its applications. Nanofiltration is a membrane separation process driven by pressure. The nanofiltration membrane is positioned between the ultrafiltration membrane and the reverse osmosis membrane, with a pore diameter of 1-2 nm and a cutoff molecular weight of 200-2000 Da. Due to various advantages such as high separation efficiency, low energy consumption, and a small footprint, nanofiltration separation is widely applied in various fields including wastewater treatment, seawater desalination, chemical separation, and food and pharmaceutical processing, and occupies an important position in modern separation and purification. The nanofiltration separation mechanism is relatively complex. Currently, nanofiltration separation performance is generally known to result from the combined action of size selection and the Donnan effect. In addition to the density of the membrane itself, significant charge selectivity exists in the nanofiltration separation process. Polyamide thin-film composite nanofiltration membranes are the most widely used commercial nanofiltration membranes; the hydrolysis of acyl chloride groups on the membrane surface forms a large number of carboxyl groups, causing the membrane surface to become negatively charged. Due to the influence of the Donnan effect, the removal rate of high-value cations is low, which limits their application in specific fields. Representative examples include the separation of Mg2+ and Li+ during lithium extraction from salt lake brine, drinking water softening, heavy metal wastewater treatment, salt purification, and the concentration and separation of specific substances in the food industry. Furthermore, positively charged nanofiltration membranes exhibit superior anti-fouling performance in the process of excluding positively charged ions and dye molecules. Based on the above, high-performance positively charged nanofiltration membranes have excellent application prospects. In addition to the charge properties of the membrane, some application scenarios require higher acid resistance. One such application scenario is wastewater treatment in wet metallurgy processes. In wet metallurgy processes, acidic leaching solutions containing metal cations such as lithium, nickel, cobalt, and manganese are obtained. Positively charged nanofiltration membranes enable the effective separation of monovalent and high-valent cations, which are then concentrated and enriched, respectively, using reverse osmosis technology to achieve the comprehensive utilization of resources. In the adsorption-membrane composite lithium extraction process, the desorption of the adsorbent proceeds under acidic conditions, causing the raw material of the nanofiltration process to become acidic. However, under acidic conditions, the C=O bonds in the polyamide structure are easily exposed to nucleophilic electron attack by H+, leading to the hydrolysis of the amide bonds. This results in damage to the membrane separation layer structure and degrades exclusion performance. Another application scenario for nanofiltration membranes is the treatment of acidic plating wastewater. Plating is a process that uses electrochemical technology to control the surface properties of metals and non-metals to achieve ideal surface corrosion resistance, conductivity, and decorative properties. Electroplating is widely used in China and generates a large amount of wastewater, accounting for approximately 20% of the total annual industrial wastewater discharge. Electroplating wastewater contains a significant amount of toxic and hazardous substances; among these, wastewater containing heavy metal ions such as copper, nickel, chromium, and zinc accounts for about 40%, and the wastewater becomes acidic due to the acid pickling activation process commonly used in electroplating. The integrated treatment of acidic electroplating wastewater is a requirement for environmental protection as well as an effective means of reducing costs and increasing efficiency through the resource recovery and recycling of industrial wastewater. Currently, the effective recovery of heavy metal ions from electroplating wastewater has become a key issue for the sustainable development of the electroplating industry. While conventional chemical precipitation methods suffer from issues such as the generation of large amounts of toxic sludge and reduced recovery rates for heavy metal resources, membrane separation technology features high separation efficiency, no secondary pollution, low energy consumption, and ease of operation. It is widely used to recover metal ions such as copper, nickel, chromium, and zinc f