CN-121972025-A - Organic solvent-resistant nanofiltration membrane and preparation method thereof

CN121972025ACN 121972025 ACN121972025 ACN 121972025ACN-121972025-A

Abstract

The application relates to an organic solvent-resistant nanofiltration membrane and a preparation method thereof, wherein the nanofiltration membrane comprises a bottom supporting layer, a middle buffer layer, a compact selective layer and a top protective layer which are sequentially overlapped, the surface of the bottom supporting layer contains active functional groups, the compact selective layer is a crosslinked polyamide network, the top protective layer is formed by solidifying fluorine-containing amphiphilic block copolymers, the middle buffer layer is a zwitterionic copolymer network containing reactive functional groups, and the zwitterionic copolymer network containing the reactive functional groups is formed by solidifying a mixed solution of zwitterionic monomers containing the reactive functional groups, wherein the reactive functional groups comprise amino groups, epoxy groups and zwitterionic structures provided by sulfobetaine methacrylate units. According to the application, by constructing a four-layer gradient structure and introducing three reactive functional groups of amino, epoxy and zwitterionic structures into the middle buffer layer, the nanofiltration membrane has excellent interface stability and separation performance under the flushing of a strong polar organic solvent.

Inventors

SUN XIAOBO
WANG BIAO

Assignees

苏州苏瑞膜纳米科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260320

Claims (10)

1. The organic solvent-resistant nanofiltration membrane is characterized by comprising a bottom supporting layer, a middle buffer layer, a dense selective layer and a top protective layer which are sequentially overlapped, wherein the surface of the bottom supporting layer contains active functional groups, the dense selective layer is a crosslinked polyamide network, the top protective layer is formed by curing a fluorine-containing amphiphilic block copolymer, the middle buffer layer is a zwitterionic copolymer network containing reactive functional groups, the zwitterionic copolymer network containing the reactive functional groups is formed by curing a mixed solution of zwitterionic monomers containing the reactive functional groups, and the reactive functional groups comprise amino groups, epoxy groups and zwitterionic structures provided by sulfobetaine methacrylate units.
2. The organic solvent resistant nanofiltration membrane according to claim 1, wherein the preparation method of the zwitterionic monomer mixed solution containing the reactive functional group comprises the following steps: Dissolving glycidyl methacrylate, sulfobetaine methacrylate and amino ethyl methacrylate in an organic solvent, adding a photoinitiator, and mixing in a dark place to obtain the mixed solution of the zwitterionic monomer containing the reactive functional group.
3. The organic solvent resistant nanofiltration membrane according to claim 2, wherein the mass ratio of glycidyl methacrylate, sulfobetaine methacrylate, and aminoethyl methacrylate is (2-3): 1-2): 1.
4. The organic solvent resistant nanofiltration membrane according to claim 1, wherein the fluorine-containing amphiphilic block copolymer is a fluorine-containing sulfonic acid-polyethylene glycol block copolymer, and the preparation steps of the fluorine-containing sulfonic acid-polyethylene glycol block copolymer are as follows: s1-1, under the protection of nitrogen, adding 2-acrylamide-2-methylpropanesulfonic acid, polyethylene glycol monomethyl ether acrylate, a RAFT chain transfer agent and a RAFT initiator into a solvent for reaction, and performing post-treatment to obtain a polymer containing a sulfonic group and a polyethylene glycol chain segment; S2-1, under the protection of nitrogen, adding the polymer and the fluorine-containing monomer prepared in the step S1-1 into water, regulating the pH value of a reaction system to 7-8, dissolving a RAFT initiator in water, adding the dissolved RAFT initiator into the water for reaction, and carrying out post-treatment to obtain the fluorine-containing sulfonic acid-polyethylene glycol segmented copolymer.
5. The nanofiltration membrane of claim 1, wherein the bottom support layer is a polyimide nonwoven fabric having hydroxyl groups on the surface.
6. The organic solvent resistant nanofiltration membrane according to claim 5, wherein the preparation method of the polyimide nonwoven fabric containing hydroxyl groups on the surface comprises the following steps: And sequentially carrying out ultrasonic cleaning on the polyimide non-woven fabric in ethanol and deionized water, drying, immersing into Tris-HCl buffer solution containing dopamine and having a pH value of 8-9 for reaction, and carrying out post-treatment to obtain the polyimide non-woven fabric with the surface containing hydroxyl.
7. The organic solvent resistant nanofiltration membrane of claim 1, wherein the crosslinked polyamide network is formed from an interfacial polymerization reaction of a diamine monomer and an acid chloride monomer.
8. The organic solvent resistant nanofiltration membrane according to claim 7, wherein the diamine monomer comprises a diamine having a rigid twisted structure selected from one or more of fluorenylcarbonyl pendant groups, biphenyl groups, spiro structures.
9. The organic solvent resistant nanofiltration membrane of claim 7, wherein the acid chloride monomer is selected from one or more of trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride.
10. A method for preparing the nanofiltration membrane resistant to organic solvents as claimed in any one of claims 1 to 9, comprising the steps of: s1-2, coating a zwitterionic monomer mixed solution containing a reactive functional group on the surface of a bottom supporting layer, and forming an intermediate buffer layer through ultraviolet irradiation crosslinking; S2-2, immersing the bottom supporting layer with the middle buffer layer into an aqueous phase solution containing amine monomers, taking out, immersing into an oil phase solution containing acyl chloride monomers, taking out, and performing heat treatment to form a compact selective layer; S3-2, coating the fluorine-containing amphiphilic block copolymer on the surface of the compact selective layer, and curing to form a top protective layer to obtain the organic solvent-resistant nanofiltration membrane.

Description

Organic solvent-resistant nanofiltration membrane and preparation method thereof Technical Field The application relates to the technical field of membrane separation material preparation, in particular to an organic solvent-resistant nanofiltration membrane and a preparation method thereof. Background Nanofiltration is used as a membrane separation technology between ultrafiltration and reverse osmosis, and is widely applied in the field of water treatment by virtue of the advantages of the molecular weight cut-off of the nanofiltration membrane being in the range of 200-1000Da, low operating pressure, high retention rate of divalent ions and small organic molecules, no phase change, easy integration and the like. With the rapid development of pharmaceutical, fine chemical and petrochemical industries, the demand of organic solvent resistant nanofiltration membranes in the separation and purification of organic systems is increasingly urgent. Polyimide is an ideal candidate material for preparing solvent-resistant nanofiltration membranes by virtue of excellent heat resistance, mechanical properties and chemical stability, and a great deal of research in recent years is devoted to the application of polyimide to a substance separation process in an organic solvent system. However, polyimide materials have a plurality of excellent properties and also have obvious defects, and the polyimide materials are mainly characterized by being easy to dissolve in polar organic solvents, so that the development of the polyimide materials in the field of solvent-resistant nanofiltration membranes is severely restricted. In order to overcome the problem, the prior art tries to improve solvent resistance of polyimide through chemical crosslinking modification, wherein the solvent resistance of polyimide is greatly reduced, the crosslinking degree is difficult to control, a multilayer composite film is built through layer-by-layer self-assembly, electrostatic interaction is easy to weaken in a strong polar solvent, structural disintegration is caused, novel solvent-resistant materials such as polybenzimidazole are developed, the film forming process is complex, the cost is high, an interface polymerization is adopted to form a selection layer, the selection layer and a supporting layer are combined only through physical adsorption, and interface stripping is easy to occur after long-term soaking in an organic solvent. In summary, the current organic solvent-resistant nanofiltration membrane still faces the core challenges in the industrialized process, namely firstly, the membrane material is insufficient in long-term stability in strong polar aprotic solvents such as DMF, NMP and the like, and is easy to swell and deform to reduce separation performance, and secondly, the interface bonding force between the separation layer and the support layer is weak, so that the separation layer is difficult to bear the shearing action of the organic solvent under high-flow-rate flushing. Therefore, a novel organic solvent-resistant nanofiltration membrane structure with high stability and high separation performance is developed, and the novel organic solvent-resistant nanofiltration membrane structure has important industrial application value. Disclosure of Invention In order to ensure that the nanofiltration membrane has high stability and high separation performance under the scouring of an organic solvent, the application provides an organic solvent-resistant nanofiltration membrane and a preparation method thereof. In a first aspect, the application provides an organic solvent-resistant nanofiltration membrane, which adopts the following technical scheme: The organic solvent-resistant nanofiltration membrane comprises a bottom supporting layer, a middle buffer layer, a dense selective layer and a top protective layer which are sequentially overlapped, wherein the surface of the bottom supporting layer contains active functional groups, the dense selective layer is a crosslinked polyamide network, the top protective layer is formed by solidifying fluorine-containing amphiphilic block copolymers, the middle buffer layer is a zwitterionic copolymer network containing reactive functional groups, the zwitterionic copolymer network containing the reactive functional groups is formed by solidifying a mixed solution of zwitterionic monomers containing the reactive functional groups, and the reactive functional groups comprise amino groups, epoxy groups and zwitterionic structures provided by sulfobetaine methacrylate units. The application designs an organic solvent-resistant nanofiltration membrane with a bottom supporting layer, a middle buffer layer, a compact selection layer and a top protection layer sequentially stacked. The inventor finds that the intermediate buffer layer containing three reactive functional groups of the zwitterionic structure provided by amino, epoxy and sulfobetaine methacrylate ester units is introduced bet