Removal of heavy metals from aqueous solutions by adsorption using natural and ammonium carbonate modified kaolinite clays

Natural kaolinite obtained from Share, Nigeria was treated with ammonium carbonate to enhance the adsorption capacity. The optimum operating conditions for of metal ions on natural clay (SK clay) were employed carbonate-treated (SK-AC clay). data analysed using isotherm and kinetic models. statistical p-values less than 0.05, indicating that model terms are significant ions. pseudo-second-order best describes mechanism. activation energy values 40 kJ mol-1 indicated physisorption. Langmuir fitted Fe2+, Zn2+ Cr6+ while Freundlich Pb2+ adsorption. Analysis thermodynamic parameters shows is spontaneous endothermic. carbonate-modified exhibited an increase in capacity 10.74 13.60 mg g-1, 16.48 17.38 g-1 11. 96 13.8 uptake decreased 8.75 7.25 g-1. results showed onto kaolin-containing cowlesite can be enhanced by treating it carbonate.