Post-treatment method for improving stability of reverse osmosis membrane and reverse osmosis membrane product

Abstract

The invention provides a post-treatment method for improving the stability of a reverse osmosis membrane and a reverse osmosis membrane product. The post-treatment method provided by the invention comprises the following steps: a) impregnating a nascent reverse osmosis membrane with a PVA solution, and removing excess solution on the surface of the nascent reverse osmosis membrane; b) drying the reverse osmosis membrane obtained in the step a) to obtain a post-treated reverse osmosis membrane product; wherein the PVA solution is prepared from the following components in parts by mass: 0.5 to 3 parts of PVA particles, 0.02 to 1.0 part of a surfactant, 0.05 to 5.0 parts of an additive and 91 to 99 parts of water; the additive is selected from one or more of polyacrylic acid, acrylic acid derivatives, cellulose ether and silicone oil. The PVA particles, the surfactant, the specific additive and the water are matched according to a certain proportion to prepare the PVA solution, so that the problems of diaphragm air leakage, poor storage stability and non-uniform coating which are respectively caused when glycerol is added or not added into the conventional PVA solution are solved.

Description

technical field [0001] The invention relates to the technical field of water treatment, in particular to a post-treatment method for improving the stability of a reverse osmosis membrane and a reverse osmosis membrane product. Background technique [0002] Seawater desalination is an important way to obtain fresh water resources. The commonly used seawater desalination methods include: seawater freezing method, electrodialysis method, distillation method, reverse osmosis method, and ammonium carbonate ion exchange method, among which reverse osmosis membrane method is one of the mainstream technologies . The principle of reverse osmosis technology is: under the pressure higher than the osmotic pressure of the solution, the solute in the solution is separated from the solvent by means of the selective interception of the semi-permeable membrane that only allows water to pass through and does not allow other substances to pass through. Using the separation characteristics of ...

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Problems solved by technology

[0005] However, as a humectant, glycerin has strong hygroscopicity. Under high temperature and high humidity environment, glycerin is easy to absorb water and swell, which leads to the occurrence of glycerol attached in the membrane pores when the polyamide reverse osmosis membrane is stored under high temperature and high humidity in summer. Swelling, resulting in the destruction of the polyamide structure on the surface of the membrane, air leakage of the membrane element rolled by the membrane, and a decrease in the desalination rate, resulting in unqualified performance

This technology is extremely harsh on the storage and transportation conditions of the diaphragm, which has caused great trouble to the product.

However, if the concentration of glycerin in the PVA solution is reduced or glycerol is not added, on the one hand, due to the high molecular viscosity of PVA, the viscosity of the PVA solution is too high, which in turn leads to serious uneven coating of the coating solution; on the other hand, PVA contains a large amount of Hydrophilic hydroxyl group has poor affinity with the membrane surface, which seriously affects the appearance of the product

Therefore, the polyvinyl alcohol (PVA) solution faces a dilemma: if glycerin is not added, the solution will be unevenly coated and affect the appearance of the product; if glycerin is added, it will easily lead to air leakage of the diaphragm when stored under high temperature and high humidity in summer. Poor storage stability also leads to unqualified performance

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