Iron removal by precipitate flotation

Abstract

The water from several artesian wells in the metropolitan area of Recife presents high iron content, preventing its use in some industrial processes. The possibility of removing the iron by the use of precipitate flotation using sodium dodecyl sulphate (SDS) as collector was studied. The tests were carried out in a glass column 65 cm high, fed by a constant airflow. At pH 8, where the isoelectric point of colloidal iron hydroxide [Fe(OH)3] was observed, the size of the precipitate increases with conditioning time and facilitates the removal of iron ions by flotation. The results showed that an increase in conditioning time, from 5 to 20 minutes, resulted in a reduction of the residual concentration of iron from 13.2 to 0.2 ppm. The decrease in precipitate specific surface area rendered a decrease in the collector consumption possible. The iron ion removal process by flotation using SDS as collector was shown to be quite efficient. A removal of 99% of Fe3+ contained in the original solution was obtained.