Amidoximated graphene/konjac glucomannan composite gel for uranium extraction from saline lake brine

Abstract

To overcome the separation defect of amidoximated graphene oxide (rGO-PAO) in uranium sorption from water solutions, the renewable natural polymer material konjac glucomannan (KGM) is selected as the immobilization reagent, since KGM can easily form gel structure and very cheap. A rationally designed strategy is developed to synthesize the new composite gel sorbent denoted as rGO-PAO/KGM. The acquired sorbents are characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and BET specific surface area analyses. All the results prove that rGO-PAO is successfully immobilized by KGM and composite gels with three dimensional (3D) sponge-like architectures are obtained. Batch uranium sorption experiments are conducted and the effects of initial solution pH, ion strength, time, uranium concentration and coexisting ions on uranium sorption are investigated. Blank KGM is found to have low uranium sorption capacity and most of uranium ions are sorbed by rGO-PAO. The maximum experimental sorption capacities are determined to be 52.6 ± 0.5 mg/g for 20-rGO-PAO/KGM. Furthermore, the sorption mechanism of uranium by rGO-PAO/KGM are revealed by using different analytical methods. Amidoxime groups are found to play the major role in uranium sorption. Uranium extraction from natural saline lake brine sample by rGO-PAO/KGM is conducted. Although the sorption capacity is not very high, rGO-PAO/KGM can be regarded as potential sorbents for uranium extraction from natural complicated waters, considering some of their superior properties.