Elimination of Sulfate Ions in Water by Addition of an Acidified Calcium Carbonate Suspension

Abstract

In humans, long-term consumption of water with sulfate levels between 500–750 mg/l can lead to laxative effects, catharsis, dehydration, and irritation of the gastrointestinal tract. As a result, sulfate removal has been widely studied by researchers globally. This study focuses on the elimination of excess sulfate ions in water under controlled stirring and by adding an acidified calcium carbonate suspension. Experimental parameters such as the mass of calcium carbonate and the concentration of hydrochloric acid are studied in order to follow the mechanism of elimination of sulfate ions. Kinetic monitoring of the residual sulfate concentration by nephelometry shows a progressive drop in the sulfate ion concentration. The variation of calcium carbonate is indifferent on the quantity of sulfates eliminated. The influence of the concentration of hydrochloric acid studied shows a maximum elimination when this concentration is 0.2 mol/L. X-ray diffraction analysis of the solids obtained revealed the presence of gypsum, thus supporting that sulfate ions are eliminated by a process that involves its formation.