Removal of fluoride from aqueous solution by adsorption on lanthanum modified attapulgite

Abstract

Fluoride pollution in natural water may create severe threats for human health. In this study, lanthanum modified attapulgite (La-ATP) was synthesized and used as a novel adsorbent for removal of fluoride in aqueous solution. Characterized results showed that the mass content of Lanthanum oxide was 3.30%. La-ATP exhibited high adsorption affinity for aqueous fluoride and the maximum adsorption amounts were 16.92, 22.03 and 25.91mg/g at 15, 25 and 35 oC, respectively. Adsorption kinetic followed pseudo-second kinetics model and adsorption rates decreased with increasing initial concentration of fluoride. The amount adsorbed of fluoride onto La-ATP decreased generally with increasing solution pH. The presence of coexisted anions in water decreased the adsorption amount of fluoride by competitive adsorption. Fluoride loaded LaATP can be easily desorbed in alkaline solution and the regenerated adsorbent still possessed high adsorption capacity for aqueous fluoride. The results implied that LaATP may be an efficient adsorbent for the removal of aqueous fluoride. KeywordsLanthanum modified attapulgite; adsorption; desorption; fluoride