The use of ladle furnace slag for the removal of hexavalent chromium from an aqueous solution

The ladle furnace slag is a by-product of the steel industry. Its adsorption potential for the hexavalent chromium ions from aqueous solutions was examined, and the results are presented in this paper. The equilibrium modeling of an adsorption proces was carried out and the equilibrium parameters were determined. The value of the maximum removal of the hexavalent chromium ions was 22.3214 mg/g at pH 4.3 and temperature of 293 K. The dynamics of an adsorption process was studied, and the values of rate constant of the adsorption, rate constant of intraparticle diffusion, and mass transfer coefficient were calculated. It was determined that the Cr(VI) adsorption mechanism is complex, while the film diffusion, and the intra-particle diffusion both contributed to the rate-determining step. Regarding the thermodynamic parameters, i.e. free energy change, enthalpy change, and entropy change, it was revealed that the Cr(VI) adsorption onto the ladle furnace slag was endothermic and spontaneous.