Two types of RO construction are commonly used: 1.
#Reverse osmosis pro ii simulation skin
The skin is the active barrier and primarily allows water to pass through. The membrane consists of a skin about 0.25 microns and a support layer about 100 microns. Many other kinds of membrane made of a single polymer or a copolymer are also available for specific purposes. The majority of the commercially manufactured RO membranes are made from cellulose acetate, polysulfonate, and polyamide. The nominal rejection ratio of common ionic salts is 85 - 98%. Monovalent ions such as chloride ions will not be rejected as efficiently as, for example, divalent sulfate ions. Ions are repelled by dielectric interactions ions with higher charges are repelled to a greater distance from the membrane surface. Salt ions, on the other hand, are rejected by a mechanism related to the valence of the ion. Most organic substances with a molecular weight over 100 are sieved out, i.e., oils, pyrogens and particulates including bacteria and viruses (13). The water molecules that enter the membrane by hydrogen bonding can be pushed through under pressure. Water molecules can form hydrogen bonds in the RO membrane and fit into the membrane matrix. If enough counter pressure is applied to the concentrated solution to overcome the osmotic pressure, the flow of water will be reversed (Figure 2). When two aqueous solutions of different concentrations are separated by a semi-permeable membrane, water passes through the membrane in the direction of the more concentrated solution as a result of osmotic pressure (Figure 1). Reverse osmosis is a process which uses a membrane under pressure to separate relatively pure water (or other solvent) from a less pure solution. This ITG will focus on the chemical and microbiological quality of water produced by reverse osmosis. In addition to these applications, RO is capable of producing water of sufficient purity to be used as Water For Injection (WFI) and for the preparation of parenteral solutions (9,10,11,12). In recent years, RO has been used increasingly in making processed water for dialysis in hospitals and for certain cosmetics and drugs by pharmaceutical manufacturers (7,8). Because RO operates at a comparatively low temperature and is relatively energy efficient, it is employed in various applications, e.g., desalination, treatment of waste water, reclamation of minerals, concentration of whey and other food products, and purification of water (5,6). Reverse osmosis (RO) has been known for more than a century, but it did not become a commercial process until the early sixties when a special membrane was developed (1,2,3,4).
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