Removal of nickel from aqueous solution by low-cost clay adsorbents

Laboratory experiments were performed to investigate the effectiveness of natural clay deposits as a potential low cost adsorbent for the removal of nickel (Ni) from wastewater. Two types of natural local clays deposits collected from Al-Mhawes Mountain, Al-Kharg prefecture and Khulais, Jeddah prefecture were examined for their abilities to remove Ni from wastewater. The effects of Ni concentrations, amount of clay added and pH of the solution on Ni adsorption were studied. The mobility of Ni and its specification were examined in a column experiment under graduate levels of clay deposits (0, 3, 6 and 9 %) and increasing Ni concentration (0, 5, and 10 mg/L) was examined. The Ni adsorption was found to be higher in the Khulais clay due to its relatively higher cation exchange capacity and specific surface area compared to Al-Mahwes clay sample. The maximum Ni adsorption capacity was observed ranges from 0.036 to 0.090 mg/g. The highest binding energy constant was obtained in case of Khulais clay deposit (1428 L/g). The adsorption data followed Langmuir and Freundlich isotherms and correlation coefficients (R2) ranged from 0.90 to 0.99. Column studies results showed that 92-99% of the added Ni was retained in the top soil layer (0-5 cm).The results indicated that local natural clay deposits were capable of removing Ni from wastewater at cost-effective and efficient adsorbent materials in Saudi Arabia.