Uranyl–graphene oxide composite membranes for enhanced photocatalytic tributyl phosphate degradation

Abstract

Tributyl phosphate (TBP), a common reagent in PUREX spent fuel reprocessing, represents a significant organic pollutant and a challenging degradation target. This study leverages the inherent photocatalytic properties of uranyl ions (UO₂²⁺) for the treatment of radioactive organic waste. A uranyl–graphene oxide (U@GO) composite membrane is facilely fabricated via a one-step impregnation method. Comprehensive characterization confirmed uranyl adsorption onto GO, inducing structural and chemical modifications. Systematic photocatalytic evaluation through rhodamine B degradation revealed significantly enhanced performance of the U@GO membrane compared to free-state uranyl ions. Application of the composite membrane to TBP degradation demonstrated excellent photocatalytic efficiency, highlighting the potential of the U@GO membrane for radioactive wastewater treatment. Combined with electron spin resonance and nuclear magnetic resonance characterization, mechanistic investigation identified that uranyl ions coordinated to the GO membrane act as the primary active sites for photocatalysis. Upon light irradiation, the generated reactive oxygen species, as well as the excited uranyl ions, attack TBP to degrade it into small, harmless molecules such as CO₂ and phosphoric acid, achieving complete mineralization. This work presents a novel approach for utilizing depleted uranium in catalytic applications and offers a promising method and material for the efficient degradation of TBP.