Principles of Water TreatmentDOE-HDBK-1015/2-93WATER TREATMENT PROCESSESRev. 0CH-04Page 3WATER TREATMENT PROCESSESOne of the more common water treatment methods is the use of demineralizersand ion exchange. This method will be discussed in this chapter.EO 1.2DEFINE the following terms:a.Ion exchangee.Polymerb.Demineralize f.Mixed-bed demineralizerc.Cationg.Affinityd.Anionh.Decontamination factorEO 1.3DESCRIBE the following:a.Resin beadb.Cation resinc.Anion resinEO 1.4DISCUSS the following factors of ion exchange:a.Relative affinityb.Decontamination factorEO 1.5WRITE the reaction for removal of NaCl and CaSO by a4mixed-bed ion exchanger such as one containing HOH resin.PrinciplesofIonExchangeIon exchange is a process used extensively in nuclear facilities to control the purity and pH ofwater by removing undesirable ions and replacing them with acceptable ones. Specifically, it isthe exchange of ions between a solid substance (called a resin) and an aqueous solution (reactorcoolant or makeup water). Depending on the identity of the ions that a resin releases to thewater, the process may result in purification of water or in control of the concentration of aparticular ion in a solution. An ion exchangeis the reversible exchange of ions between a liquidand a solid. This process is generally used to remove undesirable ions from a liquid andsubstitute acceptable ions from the solid (resin). The devices in which ion exchange occurs are commonly called demineralizers. This name isderived from the term demineralize, which means the process whereby impurities present in theincoming fluid (water) are removed by exchanging impure ions with H and OH ions, resulting+-in the formation of pure water. H and OH are present on the sites of resin beads contained in+-the demineralizer tank or column.
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