Ion Exchange Properties of Japanese Natural Zeolites in Seawater

Ion exchange properties of five different Japanese natural zeolites in seawater were examined. Sodium ions could be reduced by all zeolites, although anions, Cl- and SO42-, in seawater showed barely changes. Natural zeolite desalination treatment mainly depends on the ion exchange between Na+, K+ and Mg2+ in seawater and Ca2+ in natural zeolite. This study found that mordenite is superior to clinoptilolite for use in Na+ reduction. Mordenite with high cation exchange capacity containing Ca2+ resulted in the highest Na+ reduction from seawater.