Abstract—We attempted to prepare a desalination agent from natural zeolite and calcined hydrotalcite to reduce the salinity of seawater. Ion-exchanged natural zeolites, NH4
+-, K
+-, Mg
2+ and Ca
2+-zeolite, were prepared to remove Na+ in a solution of seawater treated with calcined hydrotalcite (CHT), and the desalination property for the mixture of ion-exchanged natural zeolite and CHT in seawater was examined, in comparison with typical synthetic zeolites, zeolite-4A and zeolite-13X. A natural Japanese mordenite-type zeolite (Iizaka mine, Fukushima prefecture) was used in this study. The behaviors of Na+ removal in solution treated with CHT (CHT-solution) using ion-exchanged zeolites is quite different from that for zeolites in seawater. Regardless of zeolite type, NH4
+-zeolite can remove higher Na+ content from the CHT-solution, and decrease the pH of the solution. Na+ removal using natural zeolite is lower than that using synthetic zeolites. The mixture of NH4
+-zeolite and CHT at the mixed weight ratio of 1:1 has better desalination properties than others because of the ion exchange with Na
+ and K
+ in aqueous solution by NH4
+-zeolite and the removal of anions and Mg
2+ and Ca
2+ by CHT. The mixture of natural zeolite and CHT possesses slightly lower desalination properties than the mixture of synthetic zeolites and CHT.
Index Terms—Desalination, salinity, natural zeolite, calcined hydrotalcite.
Takaaki Wajima is with the Department of Urban Environment Systems, Graduate School of Engineering, Chiba University, Japan (e-mail: wajima@tu.chiba-u.ac.jp).
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Cite: Takaaki Wajima, "Desalination Properties of a Natural Zeolite and Calcined Hydrotalcite Mixture in Seawater," International Journal of Chemical Engineering and Applications vol. 9, no. 4, pp. 128-234, 2018.
