Preparation of graphene oxide-manganese dioxide for highly efficient adsorption and separation of Th(IV)/U(VI)

Manganese dioxide decorated graphene oxide (GOM) was prepared via fixation of crystallographic MnO2 (alpha,gamma) on the surface of graphene oxide (GO) and was explored as an adsorbent material for simultaneous removal of thorium/uranium ions from aqueous solutions. In single component systems (Th(IV) or U(VI)), the alpha-GOM(2) (the weight ratio of GO/alpha-MnO2 of 2) exhibited higher maximum adsorption capacities toward both Th(IV) (497.5 mg/g) and U(VI) (185.2 mg/g) than those of GO. In the binary component system (Th(IV)/U(VI)), the saturated adsorption capacity of Th(IV) (408.8 mg/g)/U(VI) (66.8 mg/g) on alpha-GOM(2) was also higher than those on GO. Based on the analysis of various data, it was proposed that the adsorption process may involve four types of molecular interactions including coordination, electrostatic interaction, cation-pi interaction, and Lewis acid-base interaction between Th(IV)/U(VI) and alpha-GOM(2). Finally, the Th(IV)/U(VI) ions on alpha-GOM(2) can be separated by a two-stage desorption process with Na2CO3/EDTA. Those results displayed that the alpha-GOM(2) may be utilized as an potential adsorbent for removing and separating Th(IV)/U(VI) ions from aqueous solutions. (C) 2016 Elsevier BA/. All rights reserved.