Steel slag as a low-cost sorbent for metal removal in the presence of chelating agents

•Metals were effectively removed by steel slag in the presence of chelating agents.•Speciation of metals had a significant role in the sorption processes.•Kinetic and isotherm models supported the experimental findings.•Modification with chitosan increased the stability of steel slag.

Industrial byproduct, steel slag was used as a low-cost sorbent for the removal of Co(II), Ni(II), Cd(II), and Pb(II) from aqueous solutions containing chelating agents; EDTA, citrate, and oxalate. Equilibrium and kinetic studies were conducted. Clear dependency between speciation of metals and their sorption behavior was observed. Precipitation and adsorption were suggested as main mechanisms. Diffusion played an important role in the kinetics of metal removal. Notable leaching of elements was observed when steel slag was in contact with the solutions under study. Modification with chitosan was successfully used to prevent leaching and improve the sorption capacity of steel slag.

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