In 1748, French scholar Nollet first discovered that water in a pig’s bladder could diffuse spontaneously into an alcoholic solution on its outer surface; the pig bladder was the first naturally occurring semi-permeable membrane discovered by humankind. In 1864, German chemist Traube created a copper ferrocyanide membrane, the first man-made membrane in human history. In the 1950s and 60s, with the successful development of the world’s first asymmetric cellulose acetate reverse osmosis membrane, nanofiltration and reverse osmosis became practical membrane separation technologies, and their applications expanded rapidly. Reverse osmosis technology is mainly used for desalination of brackish water. With continuous social and economic development, the demand for energy conservation, environmental protection, and material separation is increasing, making the applications of reverse osmosis and nanofiltration even more widespread. Compared with traditional separation technologies, membrane separation technology has decisive advantages such as high separation precision, strong orientation capability, small footprint, and ease of operation and maintenance.
Modern reverse osmosis membranes can achieve higher permeate flow and desalination rates at lower operating pressures; nanofiltration membranes can provide selective separation of certain salts at even lower operating pressures.
