Removal of Mn2+ from water by bentonite coated with immobilized thin layers of natural organic matter

Abstract

A bentonite-based composite was synthesized by applying thin coatings of natural organic matter onto bentonite particles in aqueous suspension. Natural organic matter, mostly comprised of humic acids, was isolated from peat by alkaline extraction. It was insolubilized and immobilized on bentonite by heating at 350 °C in an inert nitrogen atmosphere. The composite obtained was then used to remove manganese from aqueous solutions. The results showed that manganese was removed significantly; the degree of removal was above 94% for initial concentrations of manganese from 0.250 to 10 mg/l. The effect of initial pH on manganese removal, dissolution of immobilized organic matter as well as the changes of pH and conductivity of water after treatment with composite were examined and explained.