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CN-122006472-A - Preparation method of chlorine-resistant nanofiltration membrane and chlorine-resistant nanofiltration membrane prepared by preparation method

CN122006472ACN 122006472 ACN122006472 ACN 122006472ACN-122006472-A

Abstract

The invention relates to a preparation method of a chlorine-resistant nanofiltration membrane and the chlorine-resistant nanofiltration membrane prepared by the preparation method. The method comprises the steps of preparing a base film, sequentially contacting the base film with an aqueous phase solution containing amine monomers and an organic phase solution containing acyl chloride monomers, wherein the amine monomers contain piperazine substances and pyrimidine substances with more than two amino groups, the acyl chloride monomers contain acyl chloride monomers with more than three acyl chloride groups, placing the contacted base film in an environment with the temperature of 10-30 ℃, spraying an aqueous solution containing a dialdehyde cross-linking agent, placing the base film in the environment with the temperature of 40-80 ℃ for treatment, and carrying out aftertreatment. The method has the advantages of low production cost, high production efficiency, simplicity and easiness in operation, no need of modifying the existing equipment, low use cost of the chlorine-resistant nanofiltration membrane prepared by the method, easiness in maintenance, excellent desalination performance, permeability and chlorine resistance, and excellent performance stability under long-term operation.

Inventors

  • LIU GENG
  • SONG PENG
  • KANG YAN
  • WU ZONGCE

Assignees

  • 沃顿科技股份有限公司

Dates

Publication Date
20260512
Application Date
20241111

Claims (10)

  1. 1. The preparation method of the chlorine-resistant nanofiltration membrane is characterized by comprising the following steps of: Preparing a base film, wherein the base film comprises a non-woven fabric layer and a polymer layer in sequence from bottom to top; sequentially contacting the base film with an aqueous phase solution containing amine monomers and an organic phase solution containing acyl chloride monomers, wherein the amine monomers contain piperazine substances and pyrimidine substances with more than two amino groups, and the acyl chloride monomers contain acyl chloride monomers with more than three acyl chloride groups; Placing the base film after contact in an environment with the temperature of 10-30 ℃ and spraying an aqueous solution containing a dialdehyde crosslinking agent; placing the mixture in an environment with the temperature of 40-80 ℃ for treatment; And (5) performing post-treatment to obtain the chlorine-resistant nanofiltration membrane.
  2. 2. The process according to claim 1, wherein the polymer is one or more selected from bisphenol A polysulfone, polyarylsulfone, polyethersulfone, sulfonated bisphenol A polysulfone, sulfonated polyethersulfone, polyphenylene sulfone, preferably the polymer is bisphenol A polysulfone.
  3. 3. The production method according to claim 1 or 2, wherein an intermediate layer is formed on the base film before the base film is contacted with the aqueous phase solution, preferably the intermediate layer comprises polyvinyl alcohol.
  4. 4. The process according to claim 1 or 2, wherein the piperazine is one or more selected from piperazine, 2-methylpiperazine, N-aminoethylpiperazine, 1, 4-bis (3-aminopropyl) piperazine, piperazine-2, 6-dione, trans-2, 5-dimethylpiperazine, 2-dimethylpiperazine, cis-2, 6-dimethylpiperazine, 5-dimethylpiperazine-2-one, and preferably the piperazine is present in a concentration of 0.1 to 10wt% based on the total weight of the aqueous solution.
  5. 5. The process according to claim 1 or 2, wherein the pyrimidine having two or more amino groups is selected from the group consisting of 2,4, 6-triaminopyrimidine, 4,5, 6-triaminopyrimidine, 2,4,5, 6-tetraminopyrimidine sulfate, 4, 6-diaminopyrimidine, 4, 6-diamino-2-mercaptopyrimidine, 4, 6-diaminopyrimidine-5-carbonitrile, 4, 6-diamino-5-hydroxypyrimidine, 2, 4-diaminopyrimidine, 2, 4-diamino-6-methoxypyrimidine, 2, 4-diamino-6-chloropyrimidine, 2, 4-diamino-6-hydroxypyrimidine, 2, 4-diamino-6-hydroxy-5-nitrosopyrimidine 2, 4-diamino-6-ethoxypyrimidine, 2, 4-diamino-5-hydroxymethylpyrimidine, 2, 4-diaminopyrimidine-5-carbonitrile, 2, 4-diaminopyrimidine-5-carboxylic acid, 2, 4-diamino-5-iodopyrimidine, 2, 4-diaminopyrimidine-5-carbaldehyde, 2, 4-diamino-6-ethylpyrimidine, 2, 5-diaminopyrimidine, 2, 5-diamino-4, 6-dihydroxypyrimidine, 3-bromo-2, 5-diaminopyrimidine, 4, 5-diaminopyrimidine, 2-chloro-4, 5-diaminopyrimidine, 4, 5-diamino-2-thiouracil, 2-mercapto-4-hydroxy-5, 6-diaminopyrimidine, preferably, the concentration of the pyrimidine substance with more than two amino groups is 20-50% based on the total concentration of the amine monomers.
  6. 6. The preparation method of the composition according to claim 1 or 2, wherein the acyl chloride monomer having three or more acyl chloride groups is one or more selected from the group consisting of trimesoyl chloride, biphenyl tetra-acyl chloride, ding Sanxian chloride, 1,3, 6-naphthalene tri-sulfonyl chloride, penta-triacyl chloride, cyclopropane tri-acyl chloride, cyclohexane tri-acyl chloride and hexa-triacyl chloride, preferably, the concentration of the acyl chloride monomer is 0.01-1wt% based on the total weight of the organic phase solution, preferably, the organic phase solution further comprises a solvent, and the solvent is one or more selected from Isopar E, n-hexane, n-heptane, cyclohexane, ethylcyclohexane and n-pentane.
  7. 7. The method according to claim 1 or 2, wherein the dialdehyde crosslinking agent is one or more selected from glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde, phthalaldehyde, guava dialdehyde, polyethylene glycol dialdehyde, and preferably the concentration of the dialdehyde crosslinking agent is 0.01 to 0.5wt% based on the total weight of the aqueous solution containing dialdehyde crosslinking agent.
  8. 8. The preparation method according to claim 1 or 2, wherein the aqueous phase solution further comprises an acid binding agent and a surfactant, preferably the acid binding agent is one or more selected from sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, triethylamine/camphorsulfonic acid complex system, preferably the surfactant is one or more selected from sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, sodium dodecyl benzene sulfate, triethanolamine lauryl sulfate, and ammonium dodecyl sulfate.
  9. 9. The production method according to claim 1 or 2, wherein the time of treatment in an environment at 40 to 80 ℃ is 0.5 minutes or more and less than 8 minutes, preferably 0.5 minutes or more and 7 minutes or less, more preferably 0.5 minutes or more and 6 minutes or less, the time of treatment in an environment at 40 to 60 ℃ is 0.5 minutes or more and 4 minutes or less, the time of treatment in an environment at more than 60 ℃ and 80 ℃ or less, preferably the post-treatment comprises washing with water at 60 to 80 ℃, preferably the post-treatment further comprises washing with water at 20 to 30 ℃, treatment with an aqueous solution containing glycerin, and heat drying treatment.
  10. 10. A chlorine-resistant nanofiltration membrane prepared by the preparation process according to any one of claims 1 to 9.

Description

Preparation method of chlorine-resistant nanofiltration membrane and chlorine-resistant nanofiltration membrane prepared by preparation method Technical Field The invention belongs to the field of nanofiltration membranes, and particularly relates to a preparation method of a chlorine-resistant nanofiltration membrane and the chlorine-resistant nanofiltration membrane prepared by the preparation method. Background The nanofiltration is used as one of precise membrane separation technologies, has higher interception performance on various organic matters, can moderately remove inorganic ions and retain trace elements necessary for human bodies, is one of household water purification technologies for realizing drinking water safety and health, but as the running time is increased, pollutants such as microorganisms can be attached to the surface of the membrane and grow and reproduce, and when the operating time reaches a certain degree, a biological membrane can be formed, so that the performance of the membrane is seriously reduced. Currently, to avoid microbial contamination, active chlorine is typically added to the raw water to kill or limit microbial growth and proliferation on the membrane surface. It should be noted, however, that the separation layer of nanofiltration membranes is usually made of polyamide, the chemical structure of which is extremely sensitive to active chlorine, and when it comes into contact with active chlorine, it causes a change in the chemical structure of the polyamide network and even a chain break, which still affects the polyamide layer even when it comes into contact with a lower concentration of active chlorine, resulting in a decrease in the performance of the nanofiltration membrane and an increase in the cost of use of the membrane. In order to avoid the degradation of the membrane performance caused by contact of the active chlorine with the membrane surface, some membrane applications have been augmented with a dechlorination process, i.e. removal of the active chlorine before the raw water enters the membrane section. At present, the chlorination mechanism in the reverse osmosis membrane field is more studied, and is mainly related to N-H bonds of polyamide, including reversible amide bond chlorination, irreversible Orton rearrangement, direct chlorination and hydrolysis competition mechanisms of amide groups. However, as for nanofiltration membranes, the nanofiltration membranes on the current market are mainly prepared by adopting piperazine and trimesoyl chloride as reaction monomers through interfacial polymerization reaction, and the special structure determines that the polypiperazine amide has no N-H bond. Therefore, it is mainly considered that the chlorine-resistant mechanism thereof is that unreacted amine groups undergo chlorine substitution reaction or are oxidized to hydroxylamine groups and further dehydrated to form imine groups, and the change of these unreacted amine groups causes the change of chemical and physical properties of the membrane surface, thereby causing the fluctuation of permeation and retention properties of the membrane. Based on the research on chlorine resistance mechanism, some chlorine resistance modification strategies such as surface modification, PA layer modification, support layer modification, novel separation layer construction and the like are developed successively. In patent document 1 (CN 113797762B), a chlorine-resistant nanofiltration membrane is prepared by adding carboxyl-terminated SMA into a base membrane and carrying out esterification reaction with tannic acid, but the desalination performance of the membrane is not mentioned, the congo red rejection rate of 100mg/L reaches 96wt%, in patent document 2 (CN 114887486B), mannitol is adopted as an aqueous phase monomer to prepare a polyester chlorine-resistant nanofiltration membrane by an interfacial polymerization method, in patent document 3 (CN 113230912B) and patent document 4 (CN 115646225A), polytetrafluoroethylene microporous membranes are adopted as base membranes, the chlorine-resistant nanofiltration membrane is prepared by grafting m-aminoacetylaniline modification and adopting a mixture of 4-sulfonamide o-aminophenol and amine monomers respectively, but the permeation performance of the nanofiltration membrane is not specifically disclosed, in patent document 5 (CN 109821427B), graphene oxide quantum dots are grafted to the surface of a polyamide membrane to realize the preparation of a chlorine-resistant aromatic polyamide composite nanofiltration membrane, in patent document 6 (CN 111514769B), the chlorine-resistant nanofiltration membrane is prepared by constructing a surface modification layer on the surface of the nanofiltration membrane, and the surface modification layer of the chlorine-resistant nanofiltration membrane is prepared by grafting urea and the mixture of the 4-sulfonamide o-aminophenol and amine monomer on the surface of the polyam