Efficient extraction of uranium in organics-containing wastewater over g-C3N4/GO hybrid nanosheets with type-II band structure

Abstract

The presence of organics in radioactive wastewater decreased the extraction efficiency in traditional adsorption treatment of nuclide. Herein, we developed g-C3N4/graphene oxide hybrid nanosheets (g-C3N4/GO) with the typical type-Ⅱ band structure for the phtodegradation-extraction treatment of hexavalent uranium (U(VI)) in the tannic acid (TA)-containing wastewater. Due to the staggered band structure, the photoelectron transferred from g-C3N4 to GO under simulated sunlight. Accordingly, g-C3N4/GO hybrid nanosheets exhibited promoted TA degradation and U(VI) extraction compared with the pristine g-C3N4 and GO nanosheets. In light condition, the g-C3N4/GO hybrid nanosheets degraded 92% of the TA and a 352 mg/g of U(VI) extraction capacity in 40 min. Notably, as an adverse factor for the U(VI) extraction in dark condition, the existence of TA increased the extraction capacity under simulated sunlight, which resulted from the consuming of photoinduced holes and promotion of U(VI) reduction.