Composite nanofiltration membrane based on hydrophilic modified polyolefin microporous substrate and preparation method thereof

Abstract

The invention discloses a composite nanofiltration membrane based on a hydrophilic modified polyolefin microporous substrate and a preparation method thereof. The composite nanofiltration membrane comprises a substrate and a selective cortex formed on the substrate through an interfacial polymerization reaction, and the substrate is a polyolefin microporous membrane subjected to hydrophilic modification through sedimentation; the selective cortex is formed by the interfacial polymerization reaction of an aqueous phase monomer and an oil phase monomer on the surface of the substrate; the aqueous phase monomer is at least one of piperazine, m-phenylenediamine and o-phenylenediamine; and the oil phase monomer is trimesoyl chloride. The substrate of the composite nanofiltration membrane is the polyolefin microporous membrane subjected to the hydrophilic modification through the sedimentation, a formed hydrophilic layer is thin and uniform, the surface topography of the substrate is unchanged, and the selective cortex formed on the hydrophilic layer through the interfacial polymerization is dense, uniform and defect-free, so that water flux of the composite nanofiltration membrane is large; the polyolefin microporous substrate has good tolerance for organic solvents, so that the use range of the composite nanofiltration membrane is improved.

Description

technical field [0001] The invention relates to the field of preparation of composite nanofiltration membranes, in particular to a composite nanofiltration membrane based on a hydrophilic modified polyolefin microporous substrate and a preparation method thereof. Background technique [0002] Since the 1980s, nanofiltration technology has emerged and has been widely used in wastewater treatment, seawater desalination, and water softening. Nanofiltration membranes have a high rejection rate for polyvalent salt ions and some organic molecules (molecular weight 200-1000). At the same time, compared with reverse osmosis technology, nanofiltration technology has a larger permeation flux at a lower operating pressure, so it has attracted extensive attention from industry and science. The optimization of the nanofiltration process and the preparation of the nanofiltration membrane are also one of the current research hotspots. [0003] Composite membrane is a very important type ...

AI Technical Summary

Problems solved by technology

[0008] However, the surface of traditional polyolefin microporous membranes is very poor in hydrophilicity, and the water phase in the interfacial polymerization process is difficult to disperse evenly on its surface, so it is difficult to successfully prepare a uniform and defect-free selective skin layer on its surface, which is also a constraint on polyolefin microporous membranes. The crux of the application of porous membranes to composite nanofiltration membrane substrates

However, traditional hydrophilic modification methods, such as surface grafting and plasma treatment, will damage the surface morphology of the substrate, resulting in plugging of pores and collapse of the membrane structure, which will affect the performance of the membrane.

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