1Introduction to Reverse Osmosis

　　Reverse osmosis equipment is a type of membrane water treatment equipment and is currently one of the most widely used devices for preparing pure water and high-purity water. In membrane equipment, reverse osmosis membranes can remove ion-level impurities, making the effluent meet the standards of pure water and high-purity water. The pore size of reverse osmosis membranes is extremely small (only)10ATherefore, it can effectively remove dissolved salts, colloids, microorganisms, organic matter, etc. from water (with a removal rate as high as.97－98％" The system has the advantages of good water quality, low energy consumption, no pollution, simple process and easy operation. Our company has partnerships with Nitto Denko of Japan and the United StatesHYDRANAUTICSHydranautics and DowFILMTECCompany cooperation, adoptionCADComputer simulation design ensures the scientific and reasonable nature of the system.

　　2Reverse osmosis principle

　　Reverse osmosis is a concept corresponding to osmosis. It involves applying a pressure higher than the natural osmotic pressure on one side of the concentrated solution to force the solvent (water) in the concentrated solution into the dilute solution on the other side of the semi-permeable membrane. This process is opposite to the normal osmosis process in nature. Therefore, it can intercept impurities in water on one side of the membrane and allow water to flow to the other side, thereby producing pure water and high-purity water.

　　There are two key factors for reverse osmosis facilities to produce pure water: one is a selective membrane, which we call a semi-permeable membrane, and the other is a certain pressure. Simply put, there are numerous pores on the reverse osmosis semi-permeable membrane, and the size of these pores is comparable to that of water molecules. Since viruses, most organic pollutants and hydrated ions are much larger than water molecules, they cannot pass through the reverse osmosis semi-permeable membrane and are separated from the water that passes through it.

　　3The desalination characteristics of reverse osmosis

　　Among the numerous impurities in water,Dissolved salts are very difficult to clean. Therefore, the water purification effect of reverse osmosis is often determined by the level of desalination rate. The level of desalination rate of reverse osmosis mainly depends on the selectivity of the reverse osmosis semi-permeable membrane. At present, the desalination rate of reverse osmosis membrane elements with high selectivity can be as high as99.7%. The desalination separation characteristics of reverse osmosis membranes are as follows:

　　Organic substances are easier to separate than inorganic ones.

　　Electrolytes are easier to separate than non-electrolytes. For electrolytes, the higher the charge, the better the separability. The order of removal rates of several common ions is:Al3+>Mg2+>Ca2+>Na+;PO43->SO42->CL-;

　　The removal rate of inorganic ions is influenced by the number of hydrated ions and the radius of the hydrated ions. Ions with a larger hydrated ion radius (generally, ions with a smaller ionic radius have a larger hydrated ion radius) are easier to be removed. The order of removal rates of certain cations is as follows:Mg2+,Ca2+>Li+>Na+>K+The order of anions is:F->Cl->Br->NO3-. Nitrates, permanganates, cyanides and hydrosulfides are not as easy to remove as chloride ions. The removal rate of ammonium salts is lower than that of sodium ions.

　　For non-electrolytes, the larger the molecule, the easier it is to remove.

　　Gases can easily pass through the membrane. The removal rates of gases such as ammonia, chlorine, carbonate, hydrogen sulfide and oxygen are very low. It can be converted into ions for removal.

　　The removal rate of weak acids is low, such as boric acid and organic acids. Among organic compounds, the order of removal rates is: citric acid>Tartaric acid>Acetic acid, acetaldehyde>Ethanol>amine>"Sour.

　　4Application scope

　　nearly30In recent years, reverse osmosis, electrodialysis, ultrafiltration and membrane filtration have entered industrial applications and developed rapidly. As a type of membrane filtration method, reverse osmosis is generally used in all industries that need to prepare pure water and high-purity water, mainly including:

　　The preparation of pure water and ultrapure water in industries such as electronics and medicine;

　　Purification and preparation of water for light textile and chemical industries;

　　Purification and preparation of water for beverages and brewing processes;

　　In industrial production, useful substances are concentrated and recovered from aqueous solutions.

　　Pre-desalination treatment of high-pressure boiler feed water in power plants and other enterprises;

　　Desalination of brackish water and seawater;

　　As the primary desalination equipment for high-purity water production.