Preparation method for improving desalination rate of reverse osmosis membrane

Abstract

The invention discloses a preparation method for improving the desalination rate of a reverse osmosis membrane. The invention provides the preparation method for improving the desalination rate of the reverse osmosis membrane. The preparation method is simple and convenient in preparation process and stable in desalination performance. The preparation method comprises the following steps: S1, preparing a water-phase solution and an oil-phase solution for later use; S2, preparing a membrane casting solution, coating a non-woven fabric with the membrane casting solution, and preparing a porous supporting base membrane through a phase inversion method; S3, soaking the non-woven fabric side of the porous supporting base membrane in a water phase solution, and meanwhile, soaking the polyether sulfone layer side of the porous supporting base membrane in the oil-phase solution; and S4, conducting dipping for 10-60 seconds, taking out the base membrane, drying the base membrane in a drying oven at 55 DEG C, obtaining a polyamide layer on the polyether sulfone layer side, and forming a composite reverse osmosis membrane by the polyamide layer and the porous support base membrane. According to the invention, inevitable defects on the surface of the membrane in a blow-drying process after water phase coating are avoided, and the desalination performance of the reverse osmosis membrane is improved.

Description

technical field [0001] The invention relates to the technical field of water treatment, in particular to a preparation method for improving the desalination rate of a reverse osmosis membrane. Background technique [0002] Reverse osmosis, also known as reverse osmosis, is a membrane separation operation that uses pressure difference as the driving force to separate the solvent from the solution. Reverse osmosis technology is usually used in seawater desalination, water softening treatment, wastewater treatment, purification of food, pharmaceutical industry, chemical industry, etc. With the increasing shortage of water resources and the aggravation of water pollution, the application of reverse osmosis membranes in the water treatment industry has become more and more extensive. [0003] The interfacial polymerization method is the most important method to prepare reverse osmosis membrane, which includes the following steps: [0004] 1. Coat a 20-60um thick uniform casting...

AI Technical Summary

Problems solved by technology

[0012] Water droplets remain on the surface (the inherent hydrophobicity of the polysulfone membrane surface), and contact with the oil phase solution will cause water to dissolve into the oil phase, hydrolyze trimesoyl chloride, reduce its crosslinking activity, and thus reduce the desalination rate of the membrane

[0013] If the air volume is too large, on the one hand, the water phase monomer content in the pores of the basement membrane will be reduced. During the contact with the oil phase solution, some trimesoyl chloride will react with m-phenylenediamine to form oligomers that remain in the membrane pores and block the membrane. On the other hand, part of the cross-linked structure that actually participates in the interfacial polymerization reaction decreases, resulting in a decrease in the degree of cross-linking of the membrane and a decrease in the salt rejection rate; thirdly, the concentration of amine monomers in the water phase increases, resulting in the formation of The surface potential of the membrane is reduced, and according to the Donnan effect, the interception of salt is thus reduced