Uranyl-graphene oxide composite membrane for enhanced photocatalytic tributyl phosphate degradation

Abstract

Tributyl phosphate (TBP), a common reagent in the 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 was facilely fabricated via a one-step impregnation method. Comprehensive characterizations confirmed uranyl adsorption onto GO, inducing structural and chemical modifications. Systematic photocatalytic evaluation through rhodamine B degradation revealed significantly enhanced performance of U@GO membrane compared to free-state uranyl ions. Application of the composite membrane to TBP degradation demonstrated excellent photocatalytic efficiency, highlighted the potential of U@GO membrane for radioactive wastewater treatment. Mechanistic investigation identified surface-bound uranyl species, coordinated specifically to GO substrate, as the primary active sites governing photocatalytic activity, rather than bulk adsorption capacity. Electron paramagnetic resonance (EPR) spectroscopy coupled with radical quenching experiments established photogenerated holes (h⁺) as the predominant oxidative species, with oxygen-derived radicals contributing secondarily. This work presents a novel approach for utilizing depleted uranium in catalytic applications and offers a promising new method and material for the efficient degradation of TBP.