ro reverse osmosis, also known as reverse osmosis, a pressure difference as the driving force, from the solution to separate the solvent ro membrane separation operation. Because it and natural osmosis in the opposite direction, so called reverse osmosis. According to the different osmotic pressure of various materials, you can use greater than the osmotic pressure of reverse osmosis pressure, that is, reverse osmosis method, to achieve the purpose of separation, extraction, purification and concentration.
The same volume of dilute solution (such as fresh water) and concentrated solution (such as seawater or brine) were placed on both sides of a container, separated by a semi-permeable membrane, the dilute solution of the solvent will naturally pass through the semi-permeable membrane to the concentrated solution side of the flow, the concentrated side of the liquid will be higher than the dilute solution level a certain height, the formation of a pressure version of the difference to achieve osmotic equilibrium, the difference in pressure that is osmotic pressure. The size of the osmotic pressure is determined by the type, concentration and temperature of the concentrated solution, and has nothing to do with the nature of the semi-permeable membrane. If the liquid side of the concentrated solution to apply a pressure greater than the osmotic pressure, the concentrated solution of the solvent will flow to the dilute solution, the direction of the flow of this solvent and the direction of the original direction of penetration is opposite to the process is called reverse osmosis.