High‐Capacity Cation Exchangers

Abstract

Generally speaking, all of the cation exchangers can be regenerated with common salt and used for removing calcium and magnesium from solutions. The organic cation exchangers, such as the carbonaceous zeolites and the synthetic resins, can also be regenerated with dilute acid solutions and, in the resulting hydrogen condition, they will remove all metallic cations (sodium, potassium, calcium, magnesium, iron, copper and manganese) from solution. The anion exchangers, regenerated with either sodium carbonate, caustic soda or ammonia, are used to remove the acid ions, such as the sulfates, chlorides and nitrates, from solution. Although, as indicated by the classification table, both inorganic and organic anion exchangers have been made, only the organic (synthetic resin) anion exchangers are used widely at the present time, since the inorganic materials do not have the proper characteristics for deionization application. The complete deionization process, which consists of passing water through a cation exchanger regenerated with dilute acid and then through an anion exchanger, produces a finished water comparable to distilled water in quality. In fact, recent work employing a mixture of a strongly acidic cation exchanger and a highly basic, quaternary amine type of anion exchanger in a single bed has produced water with an electrical resistance of between 10 and 20 million