Efficient photoreduction strategy for uranium immobilization based on graphite carbon nitride/perovskite oxide heterojunction nanocomposites

Abstract

The photoreduction conversion of soluble U(VI) to insoluble U(IV) is an economical strategy for the efficient removal of uranium from radioactive wastewater. A graphite carbon nitride and perovskite oxide heterojunction composite (g-C3N4/LaFeO3) is designed for the photocatalytic reduction of U(VI) under simulated sunlight conditions from aqueous solution, the reduction-immobilization mechanism is interpreted with the aid of spectroscopic evidence. The proposed heterojunction structure exhibits efficient removal ability (460 mg/g) over a wide range of U(VI) concentrations due to the suppressed recombination of photogenerated electron-hole pairs and the prolonged lifetimes of the photogenerated carriers. The catalytic efficiency is maintained at a high level after five cycles of reuse. The electrons on LaFeO3 transferred to valence band of g-C3N4, U(VI) is reduced by the electrons and ·O2− on the surface of g-C3N4. The g-C3N4/LaFeO3 heterojunction provides a promising strategy for the feasible recovery of U(VI) resources with inexhaustible solar energy.