Removal of Ni and Zn heavy metal ions from industrial waste waters using modified slag of electric arc furnace

Abstract

Abstract In the present study modified slag of electric arc furnace which itself is considered as an industrial waste material was used to eliminate nickel and zinc metals from industrial waste water. The modified slag was characterized by SEM, XRD and XRF analyses and it was demonstrated that it could be used as an efficient novel adsorbent. Experimental and thermodynamic evaluations of heavy metal removal efficiency were carried out at different conditions including temperatures of 25, 35 and 50 °C. In addition, in order to develop this process on an industrial scale, optimization of different parameters such as contact time, metallic ion concentration, adsorbent amount, adsorbent particle size, temperature, pH, etc was carried out. Results showed that the optimum conditions for removal of nickel and zinc ions were at the adsorbent dosage of 30 mg L−1, adsorbent particles size finer than 75 μm and adsorption time of 3 h. Moreover, by increasing the process temperature, the adsorbing efficiency was improved. Kinetic investigations displayed that the adsorption of metallic ions was more likely correlated with the pseudo-first-order model than the pseudo-second-order model and diffusion model. Additionally, the correlation coefficient indicated that the Freundlich adsorption model predicted more precisely than that of the Langmuir model for adsorption of nickel and zinc metallic ions.