Sorption of cesium and cobalt ions onto novel zirconium silicophosphate/polyacrylamide nanocomposite

ABSTRACT The ion exchange properties of a novel nanocomposite (nano zirconium silicophosphate/polyacrylamide) were tested against Cs+ and Co2+. Batches were constructed for kinetic and thermodynamic investigations. The highest achievable sorbed amounts of both metal ions were obtained within 120 min. Sorption kinetics of Cs+ and Co2+ followed the pseudo first- and second-order equations, respectively, and was controlled by the chemical sorption mechanisms. Diffusion of both metal ions into particles of the synthesized nanocomposite was the rate determining step. Both metal ions were weakly bonded to sorbent active sites where low values of activation energy (<42 kJ/mol) were obtained. Linear correlation of the sorption isotherm data to Langmuir and Freundlich equations confirmed the favorability of sorption processes. Raising temperature increased both of the monolayer and relative sorption capacities. The maximum sorbed amounts of Cs+ and Co2+ were calculated to be 2.06 and 8.75 mmol/g, respectively, with mean free energies reflecting the ion exchange mechanism. All sorption processes were endothermic and were occurred spontaneously where positive ΔHo and negative ΔGo quantities were obtained, respectively, with higher randomness of Cs+ than of Co2+