Utilization of steel slag as an adsorbent of ionic lead in wastewater

The feasibility of using slag, a waste from steel-making industry, as an adsorbent for ionic lead in wastewater was studied. Kinetic and equilibrium aspects of Pb²⁺ adsorption on the slag were investigated along with the effects of temperature and pH. Additionally, adsorption change at different ionic strength and desorption characteristics were also addressed. We identified that the adsorption kinetics of Pb²⁺ on the slag follows a first order reaction that can be modeled by Freundlich adsorption isotherm. It was also found that equilibrium adsorption of Pb²⁺ decreases with pH, which may be associated with the change of electrokinetic potential of slag as a function of pH. As temperature increases the adsorption capacity rises, and the data can be best fitted using van't Hoff equation. Ionic strength was found to negatively affect the adsorbability of Pb²⁺. Most of the adsorbed Pb²⁺ could be desorbed rapidly by a complexing agent, such as EDTA, which may suggest the feasibility of recycling of slag as an adsorbent for Pb²⁺.