Applicability of water-spray electric arc furnace steel slag for removal of Cd and Mn ions from aqueous solutions and industrial wastewaters

Abstract

Adsorption is a fundamental process in the physicochemical treatment of wastewaters which industries employ to reduce hazardous organic and inorganic wastes in effluents. The main objective of this study is to find a suitable application of the water-spray electric arc furnace (WS-EAF) slag which is a by-product of the steelmaking process. This material was collected, crushed, milled and characterized in terms of chemical composition, morphology and phases. The results showed that the main phases of the WS-EAF slag were magnetite (Fe3O4), wustite (Fe0.94O), beta-calcium silicate (Ca2SiO4) and mayenite (Ca12Al14O33). Several parameters were applied to evaluate the performance of WS-EAF slag for removal of Cd (II) and Mn(II) from aqueous solutions and wastewaters. Adsorption kinetics of Cd and Mn ions has been discussed. The applicability of WS-EAF slag for removal of other heavy metals (Zn, Fe, Ni, Pb and Co) from wastewaters has also been examined. The best parameters to achieve 99.99 and 99.96 (%) removal for Cd and Mn ions from aqueous solutions were found to be 10 μm adsorbent particle size, 0.5 g adsorbent weight, 8 solution pH, 90 min contact time, and 10 mg/L initial metal ions concentration at room temperature. Pseudo second-order model fits well with data of Cd and Mn adsorption. The WS-EAF slag appears to be a promising material for removal of competitive heavy metals from industrial wastewater via adsorption.