Photocatalytic uranium extraction from nuclear effluent is a promising method to avoid environmental damage and recover uranium resources. Here, the hollow tubular D-A organic semiconductor photocatalyst was fabricated by grafting 2,7-dibromo carbazole (Dbc) onto the g-C 3 N 4 (TCN) framework. The intra-molecular D-A system promoted visible light absorption, enhanced charge transfer, and improved the separation of photogenerated electron-hole pairs. Additionally, the incorporation of the carbazole structure increased the volume separation and the surface separation, adjusted the electron excitation model, and reduced the energy required for exciton dissociation. The results showed that the removal rate of U(VI) by DCN 3 reached 96.4% in 120 min and 93.3% removal of U(VI) under sunlight, and it was stable and reusable with little change under sunlight and after 5 consecutive cycles. Therefore, the D-A photocatalyst established a high photocatalytic uranium separation efficiency under sunlight and high concentrations of interfering anions and cations. This study provides insight and guidance for a deeper understanding of photocatalytic uranium separation.
Kexin Chen,Xi Wang,Pengfei Xia,Jinxin Xie,Jing Wang,Xukai Li,Yiming Tang,Laisheng Li
Z-scheme Cu 2 O-(rGO-TiO 2 ) photocatalyst was successfully synthesized via a simple three-step approach for 2,2′,4,4′-tretrabromodiphenyl ether (BDE47) reductive removal under simulated solar irradiation. Unlike the traditional heterojunction , the addition of reduced graphene oxide (rGO) enhanced the redox ability of Cu 2 O-TiO 2 by increasing charge transfer. When modifying Cu 2 O films by adding 1% rGO and coating with 70% TiO 2 , the resulting Cu 2 O-(rGO-TiO 2 ) exhibited the best photocatalytic activity for BDE47 removal. The charge transfers of Cu 2 O-(rGO-TiO 2 ) were proven to follow a Z-scheme pathway through the electron paramagnetic resonance analysis. The degradation pathways of BDE47 were elucidated by identifying intermediate products via gas chromatography-mass spectrometry (GC-MS) and gas chromatography (GC). Photo-electrons (e − ) generated from the conduction band of Cu 2 O and hydrogen protons (H 0 ) reduced from H + in water were the main contributing elements for the removal of BDE47, which response to the ortho and para debromination . Ortho-Br of BDE47 was attacked by e − and BDE28 was the dominant debromination product on the first stage. Then e − and H 0 attacked ortho-Br and para-Br of BDE28 to form BDE15 and BDE8, respectively. The concentration of BDE8 was higher than that of BDE15, suggesting that H 0 played the most important role on the second debromination stage. An effective Cu 2 O-(rGO-TiO 2 )-based Z-scheme system for BDE47 debromination was proposed in this study, which may contribute to the development of novel green technologies.
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