Removal of NaCl from seawater using natural zeolite

Abstract

We attempted to develop a new process to remove NaCl content in seawater using natural zeolite. Na+ in seawater can be reduced by ion exchange of natural zeolite, and Cl− can be reduced by AgNO3 or calcined hydrotalcite. The two-step process, which comprised natural zeolite treatment and anion reduction treatment (AgNO3 or calcined hydrotalcite), was applied to remove NaCl from the seawater. The possibility of cultivation using the obtained solution for the growth test of radish sprouts was then examined. The latter did not grow in the seawater, the solution treated with natural zeolite, the solution treated with AgNO3 after zeolite treatment, and in the solution treated with natural zeolite after AgNO3 treatment, due to the high contents of Cl− and remaining in these solutions. Radish sprouts also did not grow in the solution treated with calcined hydrotalcite because of high pH and high content of Na+ in the solution. By combination of anion reduction treatment using calcined hydrotalcite and zeolite treatment, radish sprouts can be grown in the prepared solution.