Enhanced sorption of Cu2+ from sulfate solutions onto modified electric arc furnace slag

Pristine electric arc furnace slag (EAFS) as well as EAFS modified by alkali activation i.e. alkali activated slag (AAS) have found a novel application as adsorbents used in Cu2+ removal from sulfate solutions. The adsorption tests were carried in batch conditions and results have shown that alkali activation of EAFS enhances the Cu2+ adsorption. The adsorption process was found to follow a pseudo second-order kinetic model and occurs via formation of posnjakite (Cu4(SO4)(OH)6·H2O) on the surface of both, EAFS and AAS. Enhanced adsorption properties of AAS, compared to EAFS, are attributed to a more porous structure, larger specific surface area and an increased number of surface groups involved in the binding of Cu2+.