The development of RO membranes has roughly gone through 3 stages. The RO membrane materials commonly used in China mainly include cellulose acetate membrane (CA film), aromatic polyamide membrane (PA film) and chitosan membrane (CS film). CA film is the earliest membrane material, odorless, tasteless, non-toxic, stable to light, strong hygroscopicity, but CA film has poor chemical stability, thermal stability, compaction, and easy degradation. PA membrane is the most commonly used RO membrane in industry, with physical and chemical stability, resistance to strong alkali, oil esters, organic solvents, good mechanical strength and other advantages, but PA film has charge, water particles are easy to deposit on the surface of the membrane, forming membrane pollution, shortening the service life. CS membrane is a natural polymer membrane material, non-toxic, no side effects, antibacterial, alkaline earth metal ion removal ability is strong, is a more superior hard water softening RO film, is a very potential membrane material, has received great attention in the world.
Recent developments in RO membranes include inorganic membranes, hybrid membranes, and novel organic membranes. Theoretically, inorganic membrane ion retention performance is very high, but the cost is high and the preparation conditions are harsh, which is not conducive to industrial application. Hybrid membrane integrates the advantages of organic materials and inorganic materials, and has a good application prospect in improving membrane separation performance and anti-pollution, and has great development potential, which needs further theoretical research. The preparation of new organic membranes is still in its infancy, the main purpose is to improve membrane flux and chemical stability, and no breakthrough has been made.
