Analytical Sciences

Ion Exchange Properties of Japanese Natural Zeolites in Seawater

Takaaki WAJIMA

Department of Applied Chemistry, Graduate School of Engineering and Resource Science, Akita University, 1-1 Tegata-gakuen, Akita 010-8502, Japan

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.

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