Efficient visible-light-driven photoreduction of U(VI) by carbon dots modified porous g-C3N4

Abstract

The efficient removal of uranium from radioactive wastewater is of great significance for the ecological environment safety and sustainable development of nuclear energy. Herein, the carbon dots modified porous graphitic carbon nitride (CNCD) was fabricated and used for photoreduction of U(VI) under visible LED light irradiation. The removal rate of U(VI) by CNCD-2 could reach more than 95 % over a wide range of U(VI) concentration. In addition, the CNCD-2 showed excellent selectivity and recyclability for photoreduction of U(VI). Further mechanism studies showed that the high photocatalysis activity of CNCD-2 was attributed to the effective separation of photoinduced electron-hole pairs, strong visible light absorption capacity and narrow bandgap. The U(VI) was activated by both photoinduced e- and •O2– in the process of photoreduction, and then immobilized by transforming it to metastudtite ((UO2)O2·2H2O). These results indicate that the CNCD is a promising material for remediation of uranium-containing wastewater under visible light irradiation.