INVESTIGATION OF THE USE OF WALNUT SHELLS AS A NATURAL BIOSORBENT FOR ZINC REMOVAL

Abstract

Heavy metal contamination is a primary concern worldwide and it is discharged from the industrial wastewater to a large amount of heavy metal receiving environments. In recent years, the effective use of agricultural by-products is definitely a major challenge in waste management. The fact that agricultural residues are more easily obtained and cheaper than commercial adsorbents makes it attractive. In this study, removal of zinc from industrial wastewater using natural and thermally modified (biochar) walnut shells as biosorbent was investigated. It was tried to remove zinc in aqueous solutions with different concentrations by using walnut shells at different rates. The effects of initial concentration, contact time, adsorbent dosage. In addition, adsorption isotherms and kinetics were also studied. With the modified form of the walnut shell, up to 98% zinc removal efficiency was obtained. Also, adsorption was observed to be consistent with pseudo-second kinetics and Freundlich isotherm. The results showed that the modified walnut shell in zinc removal was a potential adsorbent. The adsorption of zinc, onto walnut shells was found to fit Freundlich isotherm. The results obtained in the tests with wastewater showed the potential use of walnut shells for the removal of zinc.