Explanation

This is a kind of reverse osmosis membrane, also known as nanofiltration membrane or loose reverse osmosis membrane. The pore size of this membrane is usually around 1 to 2 nanometers, allowing solvent molecules or certain low molecular weight solutes or low valent ions to pass through, making it a functional semi permeable membrane. nanofiltration membrane has ion selectivity, in which there are functional groups with negative electricity on the surface or inside of the membrane, which can block the penetration of multivalent ions through electrostatic interaction. The nanofiltration membrane usually needs to be operated under the operating pressure of 3.5 to 30 bar, which can intercept organics and high valence inorganic salts with molecular weight of about 150 to 500. nanofiltration membrane can be made into different materials, including cellulose acetate, sulfonated polyether sulphone, polyimide, polyethylene, etc. One of the earliest application areas was seawater desalination. In water treatment, it is often used to remove pigment, low molecular weight organics, suspended solids, disinfection by-products (such as chloroform and haloacetic acid) and their precursors, and to separate heavy metals. nanofiltration membrane has excellent ability to remove chromaticity, hardness, odor, etc. In addition, it is also used for the extraction and concentration of useful substances in food and pharmaceutical production.

Classification