Adsorption characteristics of Th(IV) ions on reduced graphene oxide from aqueous solutions

Reduced graphene oxide (RGO) prepared by the reduction of graphene oxide (GO) using thiourea dioxide (TUD) was examined for the adsorption of Th(IV) from aqueous solutions. The adsorption of Th(IV) on RGO as a function of pH, contact time, adsorbent dosage, the Th(IV) initial concentration and temperature was investigated through batch adsorption experiments. The results showed that the adsorption behavior of Th(IV) on RGO followed the pseudo-second order kinetic and the Langmuir isotherm models. The maximum theoretical adsorption capacity was calculated to be 0.21 mmol Th/g RGO at 298.15 K. Moreover, the thermodynamic parameters (ΔH0 = 4.32 kJ/mol, ΔS0 = 69.47 J/mol K and ΔG0 = −16.39 kJ/mol at 298.15 K) indicated that the adsorption process was a feasible, spontaneous and endothermic in nature.