Adsorption of Zinc and Copper Ions by the Solid Waste of the Olive Oil Industry

Abstract

The adsorption capacity of dried olive oil husks (SWOOI) for zinc ions (Zn²⁺) and copper ions (Cu²⁺) was studied. It was verified that the Freundlich and Langmuir isotherms describe the adsorption of Cu²⁺ and Zn²⁺ ions reasonably well. Up to 90% of Zn²⁺ ions and 80% of Cu²⁺ ions were adsorbed from aqueous solutions when the initial adsorbent and metal concentrations were 30 mg/ml and 20 ppm, respectively. An increase in the SWOOI concentration resulted in greater metal removal from the aqueous solution, and an increase in Zn²⁺ ion or Cu²⁺ ion concentration at constant SWOOI concentration increased the metal loading per unit weight of the adsorbent. An increase in the initial pH of the metal solutions enhanced the SWOOI adsorption process. The uptake of Zn²⁺ ions was also enhanced by decreasing the SWOOI particle size. The presence of a high concentration of soft ions (Na⁺) strongly suppressed the uptake of Zn²⁺ ions by SWOOI.