From Waste to Waste: Iron Blast Furnace Slag for Heavy Metal Ions Removal from Aqueous System

Abstract

Blast furnace slag (BFS) is considered a cheap sorbent for the get rid of Co2+ and Pb2+ ions from an aqueous medium. The slag is characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), N2 adsorption-desorption isotherms, energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), and zeta potential. The removal of Co2+ and Pb2+ ions was carried out using batch adsorption experiments from an aqueous medium. The influence of several variables as pH, duration, sorbent quantity, temperature, and preliminary ions concentration was considered. The isotherm, kinetic, thermodynamic, and recyclability were also conducted. The maximum uptake capacity for Co2+ and Pb2+ was 43.8 and 30.2 mg g-1 achieved at pH 6 after 60 min. contact duration. The adsorption kinetics and isotherms of BFS for Co2+ and Pb2+ fitted well to Avrami and Freundlich models, respectively. The main sorption mechanism between BFS and the metal ions was ion exchange. The regeneration of the used slag was studied for reuse many cycles. In terms of economics and scalability, the treatment with the unmodified BFS has great potentials.