Adsorption kinetics, isotherms, and thermodynamic studies for the adsorption of Pb²⁺ and Hg²⁺ metal ions from aqueous medium using Ti(IV) iodovanadate cation exchanger

In the current study, Ti(IV) iodovanadate cation exchanger (TIV) was synthesized and applied for the removal of Pb2+ and Hg2+ metal ions from the aqueous medium. The adsorption studies were performed by the batch techniques and adsorption parameters viz. contact time, pH, initial metal ion concentration, and temperature were also investigated. The optimum adsorption of Pb2+ (95 %) and Hg2+ (65 %) were observed at pH 6. The pseudo-second order equation represented the adsorption kinetics with high correlation coefficient. Langmuir model showed the best fitting to the isotherm equilibrium data, with a maximum adsorption capacity of 18.8 mg g−1 for Pb2+ and 17.2 mg g−1 for Hg2+. Furthermore, thermodynamic factors, i.e., ΔG, ΔH, and ΔS, indicated that adsorption of Pb2+ and Hg2+ onto TIV were spontaneous, endothermic, and feasible in the temperature range of 293–323 K.