What are the differences between ultrafiltration membrane, nano filtration membrane and RO reverse osmosis membrane?

According to the filtration accuracy, it can be divided into ultrafiltration membrane, nano filtration membrane and RO reverse osmosis membrane. The pore size of ultrafiltration membrane is 0.01μm, which can intercept colloid, rust, sediment and macromolecular organic matter. The pore size of nano filtration membrane is 1 ~ 2nm, which can remove calcium and magnesium ions, odor, color, pesticide, soluble organic matter, etc. The RO reverse osmosis membrane has the highest filtration accuracy, its pore size is 0.0001μm, the diameter of virus is generally 0.02-0.4μm, and the diameter of ordinary bacteria is 0.4-1μm, so it can filter out inorganic salts, heavy metal ions, organic matters, viruses, bacteria, etc. The water is pure from RO reverse osmosis water purifier.

The three water purification settings of the three purifiers are the same, namely, the first water purification polypropylene melt blown filter core (i.e. ppcotton filter element), the second water purification granular activated carbon filter element and the third carbon rod filter element. After the three filtration, it can filter out rust, sediment, metal ions, small molecules of organic matter, adsorption of residual chlorine, color, odor, mailing small molecules. As for the first filtration device - ppcotton filter element, its advantages and disadvantages mainly lie in the accuracy gap. The higher the accuracy, the more solid particles can be intercepted. For example, 1 micron can intercept more solid particles than 5 microns.

The difference lies in the fourth green water device, which is the ultrafiltration membrane, nano filtration membrane and RO reverse osmosis membrane filtration. The fifth is the same post composite filter element, which is composed of ultrafiltration membrane and granular activated carbon, which can filter again and improve the taste of drinking water.

The structure and working principle of ultrafiltration membrane and RO reverse osmosis membrane are completely different. The ultrafiltration membrane is similar to a circle of vermicelli like hollow fiber, which is relatively loose. Water can be filtered directly through the hollow fiber without electricity. The working principle of RO reverse osmosis membrane is a process in which the purified water pressure is higher than the osmotic pressure as the driving force, and the selective permeability of selective membrane can only penetrate water but not solute, so as to separate water molecules from solute phase. Therefore, RO reverse osmosis water purifier is equipped with a water pump (i.e. motor) that can provide external pressure, so it needs electricity to filter water.

However, there are several RO reverse osmosis membrane water purifiers with the same water purification principle on the market. On the basis of RO reverse osmosis membrane, some have added ultraviolet sterilization function, some have added filter element replacement reminder function, and some use imported activated carbon. Each has its own selling point and its price varies greatly. But in fact, the ultraviolet sterilization of household water purifier is only an auxiliary function.