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

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 steel-making 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 mu m 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.