Nanofiltration (NF)
Introduce
Nanofiltration Membranes is a new type of separation membrane that was introduced in the late 1980s. The molecular weight of its interception is between reverse osmosis membrane and ultrafiltration membrane, which is about 200-2000. Therefore, it is speculated that nanofiltration membrane may have microporous structure of about LNM, so it is called "nanofiltration membrane". Most of the nanofiltration membranes are composite membranes, whose surface and separation layer are composed of polyelectrolyte, so they have a certain rate of interception to inorganic salts. Most of the nanofiltration membranes that have been commercialized in foreign countries are composed of an ultra-thin separation layer with nanoscale pore diameter on the microporous membrane by boundary condensation and shrinkage.
Nanofiltration membrane material: polyamide material
Nanofiltration membrane (NANofiltration membrane) : material with nanoscale (0.001 micron) retention capacity. Nanofiltration membrane operation interval between ultrafiltration and reverse osmosis, the intercept molecular weight of organic matter is about 200-800 - mw or so, the ability to intercept dissolved salts to between 20% and 98%, the soluble removal rate is lower than the high price of monovalent ions, nanofiltration is generally used to remove the organic matter and pigments in the surface water, groundwater hardness and radium, and partial removal of dissolved salts, the extraction of useful substances in food and medicine production and enrichment. The operating pressure of nanofiltration membrane is general 3.5-30bar。
Advantages
1. The process of concentration and purification is carried out at room temperature without phase transition, chemical reaction, other impurities and decomposition and degeneration of the product. It is especially suitable for heat-sensitive substances.
2. It can remove salt, reduce ash content, improve product purity, and improve product quality and yield compared with solvent desalination.
3. High yield and little loss in the process
4. The acid, alkali, alcohol and other effective substances in the solution can be recovered to realize the recycling of resources
5. The equipment has compact structure, small floor space and low energy consumption
6. Easy to operate, automatic operation can be realized, good stability, easy maintenance.
