摘要
Ni adsorption on various single and dual site clays (gibbsite, goethite, natural red earth and leterite) was determined using batch experiments as a function of pH, background electrolyte concentration and adsorbate loading. The experimental data was quantified by 2-pK surface complexation modeling using monodentate and bidentate surface reactions. Gibbsite and laterite showed higher retention of Ni compared to natural red earth (NRE) and goethite indicating high affinity to AlOH surface sites of all clays. The maximum adsorption density of 9.0 脳 10鈭? mol m鈭? was reported for gibbsite. All four sorbents showed a negligible variation with ionic strength. The Ni adsorption capacity, i.e., 螕Ni, varied with the type of sorbents used in accordance with the following order: 螕Gibbsite Ni > 螕Laterite Ni > 螕NRE > 螕Goethite Ni. In all cases, the estimated Gibb's free energy parameter showed that the Ni(II) adsorption was spontaneous.