Method for preparing pollution-resisting reverse osmosis polyamide composite membrane

Abstract

The invention belongs to a method for preparing a pollution-resisting reverse osmosis polyamide composite membrane, which is characterized in that a surface of a reverse osmosis polyamide composite membrane is processed by a compound solution with epoxy groups or isocyanic acid groups or silica groups for a certain time, thus the epoxy groups or isocyanic acid groups or silica groups are reacted with reactive perssad in polyamide molecules so as to be bonded on the membrane surface and enable charges on the membrane surface to tend to be neutral; and the bonding is utilized to introduce hydrophilic groups on the membrane film to increase hydrophilcity on the membrane surface or elements for reducing surface energy so as to decrease surface energy of the membrane, thereby improving the pollution-resisting capacity of the membrane. The adhesive strength of a compound coating on the membrane surface is improved by the bonding, thereby prolonging the service life of the pollution-resisting membrane.

Description

technical field [0001] The invention relates to a method for manufacturing a pollution-resistant polyamide reverse osmosis composite membrane, and belongs to the technical field of semipermeable membrane preparation methods. Background technique [0002] Nanofiltration and reverse osmosis membranes have become one of the key technologies for water treatment due to their excellent separation performance for small organic molecules and inorganic salt ions, as well as safety, environmental friendliness, and easy operation. Its applications include seawater and brackish desalination, hard water softening, reclaimed water recovery, industrial wastewater treatment, ultra-pure water preparation, etc. Among them, the composite membrane has become the fastest-growing and most widely used membrane variety because of its ability to optimize the membrane’s rejection rate, water flux, and stability. Currently, more than 90% of the nanofiltration and reverse osmosis membranes on the marke...

AI Technical Summary

Problems solved by technology

Due to the chemical structure and surface properties of the polyamide composite membrane, the anti-pollution ability of this type of composite membrane is very weak, which increases the cleaning cost and service life of the membrane

In order to improve the anti-pollution ability of polyamide composite membranes, a lot of work has been done at home and abroad, mainly focusing on surface modification and surface coating. Hydrophilic groups improve the anti-pollution properties. At present, plasma treatment is limited by technical conditions and costs and cannot be applied to large-scale mass production.

Chinese patent 02126106.7 and U.S. patent US6913694 use a layer of epoxy compound hydrophilic coating containing more than 2 epoxy groups on the surface of the composite film. Due to the limitation of the density of the hydrophilic group, it cannot improve the hydrophilicity of the film surface to the greatest extent. water performance

U.S. Patent US5151183 uses fluorine gas to fluorinate the membrane surface to improve the anti-pollution performance of the membrane. Fluorine gas treatment easily cracks the polyamide molecules on the membrane surface, thus affecting the desalination performance and life of the membrane

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