Removal of Mg2+, K+, SO4-2 ions from seawater by precipitation method

Abstract

Removal of Mg2+, K+, and SO4-2 ions in seawater has been successfully done by precipitation in a mixing tank method. This study aims to remove the content of magnesium ions (Mg+), potassium (K+) and sulfate (SO4-2) in sea water with the addition of chemicals disodium phosphate (1.2 % volume), calcium chloride (2 % volume) and sodium hydroxide (2% volume). Stirring is performed at 100 rpm and the pH solution is adjusted to 9. Disodium phosphate serves to bind magnesium ions and potassium, CaCl2 serves to bind the sulfate ion, while sodium hydroxide is used to adjust the pH of the solution mixture and also reacted with magnesium ions. In total, the removal efficiencies of Mg2+, K+ and SO4-2 ions in seawater were 97%, 96%, and 92%, respectively. The precipitated solids contains component of PO4- (14.5%), Mg2+(13.8%), SO4-2 (28.2%), Ca2+ (24.1%) and K+ (1.9%) ions.