High effective enrichment of U(VI) from aqueous solutions on versatile crystalline carbohydrate polymer-functionalized graphene oxide.

The removal of uranium on various sorbents has been widely employed in recent times. However, the limited sorption capacities of these sorbents inhibit the actual application of the radionuclide in actual environments. The development of a novel material with high sorption capacity and superior regeneration for the removal of uranium is highly desirable. Therefore, a versatile class of crystalline carbohydrate polymers (COF) was prepared from organic compounds. Moreover, COF-functionalized graphene oxide (COF/GO) was synthesized and tested for the removal of U(VI) from aqueous solutions. The batch characterization showed that COF was vertically oriented on the surface of GO using diboronic acid as nucleation sites. The maximum removal capacity of U(VI) on COF/GO reached 117.67 mg g-1, and was attributed to a huge void ratio and various oxygen-bearing functional groups. In addition, the inner-sphere surface-complexation dominated the U(VI) removal, and the adsorption mechanism of inner-sphere surface-complexation was transferred into surface precipitation with increasing reaction time. COF/GO can be converted into conductive carbon and reduced GO (C/rGO) nanocomposite, which has high specific capacitance. These results suggested that GO-based materials can be considered as promising candidates for the enrichment of U(VI) and energy storage.