Preparation method of composite desalination layer nanofiltration membrane

Abstract

The invention relates to a preparation method of a composite desalination layer nanofiltration membrane. The method comprises the following steps of coating a polysulfone ultrafiltration base membranewith a polyvinyl alcohol-polyethyleneimine mixed solution containing a crosslinking agent and a catalyst, and carrying out crosslinking reaction to form a positively charged desalination layer on a surface of the polysulfone ultrafiltration base membrane; cleaning the membrane by using a solution containing an acid absorbent to remove sulfuric acid and glutaraldehyde which does not participate inthe reaction; removing water drops on the surface of the membrane, applying an oil phase solution, and allowing a large number of amine chain segments which do not participate in the cross-linking reaction on a surface of the positively charged desalination layer to react with polyacyl chloride in the oil phase to generate a polysulfonyl chloride desalination layer. According to the technical scheme, a thin polysulfonamide desalination layer can be obtained, meanwhile, the compactness of the polysulfonamide desalination layer can be improved by prolonging the reaction time without worrying about the influence on the flux due to the formation of an over-thick desalination layer, the problems that the reaction speed of polyamine and polyacyl chloride is low, and polyamine molecules penetrate through a loose primary desalination layer to diffuse to an oil phase such that a finally formed desalination layer is large in thickness and low in flux can be solved.

Description

technical field [0001] The invention relates to the technical field of polymer separation membranes, in particular to a method for preparing a composite desalination layer nanofiltration membrane. Background technique [0002] Nanofiltration membrane is a separation membrane with nanoscale separation pore size and charged surface. The separation accuracy of the nanofiltration membrane is between that of the reverse osmosis membrane and the ultrafiltration membrane, and it can allow low-valent ions to pass through partly or completely while intercepting high-valent ions or organic substances with higher molecular weight. Compared with reverse osmosis membrane, nanofiltration membrane has lower operating pressure and higher membrane flux. It is a relatively energy-saving membrane separation technology and is widely used in water softening, industrial wastewater treatment, material separation and concentration and other fields. Currently commercially available reverse osmosis ...

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Problems solved by technology

[0007] For this reason, the embodiment of the present invention provides a method for preparing a composite desalination layer nanofiltration membrane, which can overcome the slow reaction speed of polyamines and polyacyl chlorides, and the diffusion of polyamine molecules into the oil phase through the loose primary desalination layer leads to the final desalination Problems with higher layer thickness and lower flux

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