D-π-A array structure of Bi4Ti3O12-triazine-aldehyde group benzene skeleton for enhanced photocatalytic uranium (VI) reduction

• Published in: Journal of hazardous materials 2023-06, Vol.451, p.131189-131189, Article 131189
• Main Authors: Liu, Xin, Bi, Rui-Xiang, Yu, Feng-Tao, Zhang, Cheng-Rong, Luo, Qiu-Xia, Liang, Ru-Ping, Qiu, Jian-Ding
• Format: Article
• Language: English
• Subjects: Bismuth titanate; D-π-A array; Photocatalytic reduction; Post-synthesis; Uranium
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2023.131189

Photocatalytic reduction of UVI to UIV can help remove U from the environment and thus reduce the harmful impacts of radiation emitted by uranium isotopes. Herein, we first synthesized Bi4Ti3O12 (B1) particles, then B1 was crosslinked with 6-chloro-1,3,5-triazine-diamine (DCT) to afford B2. Finally, B3 was formed using B2 and 4-formylbenzaldehyde (BA-CHO) to investigate the utility of the D-π-A array structure for photocatalytic UVI removal from rare earth tailings wastewater. B1 lacked adsorption sites and displayed a wide band gap. The grafted triazine moiety in B2 introduced active sites and narrowed the band gap. Notably, B3, a Bi4Ti3O12 (donor)-triazine unit (π-electron bridge)-aldehyde benzene (acceptor) molecule, effectively formed the D-π-A array structure, which formed multiple polarization fields and further narrowed the band gap. Therefore, UVI was more likely to capture electrons at the adsorption site of B3 and be reduced to UIV due to energy level matching effects. UVI removal capacity of B3 under simulated sunlight was 684.9 mg g−1, 2.5 times greater than B1 and 1.8 times greater than B2. B3 was still active after multiple reaction cycles, and UVI removal from tailings wastewater reached 90.8%. Overall, B3 provides an alternative design scheme for enhancing photocatalytic performance. [Display omitted] Photocatalytic UVI reduction is one of the most promising methods to reduce radioactive uranium contamination in tailings wastewater. Herein, a Bi4Ti3O12 (donor)-triazine (π-electron bridge)-aldehyde benzene (acceptor) crosslinked molecule, named B3, was formed D-π-A array structure for significantly improving photocatalytic UVI removal performance from tailings wastewater. The improved performance of B3 is due to the increased adsorption sites on the triazine and the increased electron push-pull effect of aldehyde group benzene as a weak acceptor for extended electron delocalization, resulting in the formation of multiple polarization fields. The modulation of D-π-A array structure provides an alternative means to improve photocatalytic performance. •Bi4Ti3O12-triazine unit-aldehyde benzene molecule formed D-π-A array structure.•The D-π-A array structure can form multiple polarization fields.•The D-π-A array structure can regulate band gap width and charge transfer.•The modulation of D-π-A structure can improve photocatalytic performance.