A reverse osmosis membrane is an artificial semi-permeable membrane with specific characteristics, mimicking a biological semi-permeable membrane. It is the core component of reverse osmosis technology. The principle of reverse osmosis is that, under pressure higher than the osmotic pressure of the solution, substances that cannot pass through the semi-permeable membrane are separated from water. The membrane pores of a reverse osmosis membrane are extremely small, thus effectively removing dissolved salts, colloids, microorganisms, and organic matter from water. The system offers advantages such as good water quality, low energy consumption, no pollution, simple process, and easy operation.
The reverse osmosis membrane is the core component for achieving reverse osmosis; it is an artificial semi-permeable membrane with specific characteristics, mimicking a biological semi-permeable membrane. It is generally made of polymeric materials, such as cellulose acetate membranes, aromatic polyhydrazide membranes, and aromatic polyamide membranes. The diameter of the surface micropores is generally between 0.5 and 10 nm, and the permeability is related to the membrane's chemical structure. Some polymeric materials have good salt repellency but poor water permeation. Other polymeric materials have more hydrophilic groups in their chemical structure, resulting in relatively faster water permeation. Therefore, a satisfactory reverse osmosis membrane should have an appropriate permeate flow rate or desalination rate.