Adsorption of uranium (VI) from aqueous solution using a novel graphene oxide-activated carbon felt composite

Graphene oxide(GO)-activated carbon felt(ACF)(GO-ACF) composite was prepared by an electrophoretic deposition and subsequent thermal annealing. The structures of GO and GO-ACF were characterized by FT-IR, Raman spectra and XPS. The adsorption capacities for U(VI) from aqueous solution of ACF and GO-ACF were compared. The essential factors affected U(VI) adsorption such as initial pH, contact time and temperature were investigated. The adsorption is highly dependent on the solution pH. In addition, the adsorption isotherm and thermodynamics were investigated. The adsorptions of U(VI) from aqueous solution on GO-ACF were fitted to the Langmuir and, Freundlich adsorption isotherms. The adsorption of U(VI) could be well-described by Langmuir. The adsorption of U(VI) on ACF is remarkably improved by GO covalently bonding with ACF. The maximum sorption capacity of GO-ACF for U(VI) was evaluated to be 298 mg/g at pH 5.5, much higher than that of ACF (173 mg/g), suggesting the carboxyl functional groups of GO-ACF playing important roles in the sorption. Thermodynamic parameters further show that the sorption is an endothermic and spontaneous process. GO-ACF is a powerful promising sorbent for the efficient removal of U(VI) from aqueous solutions.