Arsenite removal by adsorption onto iron oxide-coated pumice and sepiolite

Abstract

The present study describes the removal of arsenite by iron oxide-coated pumice and iron oxide-coated sepiolite. Pumice and sepiolite were coated with iron oxide and used as adsorbents for the removal of arsenite from aqueous solution in batch experiments. Arsenite concentration decreased exponentially with time, and equilibrium was attained in 84 h. The kinetics of the adsorption process was tested for the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The adsorption of arsenite onto iron oxide-coated pumice and iron oxide-coated sepiolite followed the pseudo-second-order model. Freundlich, Dubinin-Radushkevitch, and Temkin isotherm models were applied to the experimental equilibrium data. The adsorption of arsenite fit these isotherm models. The results indicated that the iron oxide-coated pumice and iron oxide sepiolite could be alternative adsorbents for arsenite removal. Among the adsorbents, iron oxide-coated pumice was found to be more effective than iron oxide sepiolite in the removal of arsenite.