Efficient photodegradation of PFOA using spherical BiOBr modified TiO 2 via hole-remained oxidation mechanism

• Published in: Chemosphere (Oxford) Vol. 298; p. 134176
• Main Authors: Chen, Fengjie, He, Anen, Wang, Yarui, Yu, Wanchao, Chen, Haoze, Geng, Fanglan, Li, Zhunjie, Zhou, Zhen, Liang, Yong, Fu, Jianjie, Zhao, Lixia, Wang, Yawei
• Format: Journal Article
• Language: English
• Published: England 01.07.2022
• Subjects: Direct oxidation with holes; Holes remained; PFOA photodegradation; BiOBr-Modified TiO

Photo-induced holes (h ) oxidation is an efficient approach for perfluorooctanoic acid (PFOA; C F COOH) removal. To maintain a high amount of h on the surface of photocatalysts participating in the PFOA photodegradation could be a critical issue. Herein, a highly efficient spherical BiOBr-modified nano-TiO (P25) was synthesised and used for PFOA photodegradation through direct oxidation with h . A high number of h could be generated and remain on the surface of P25/BiOBr due to the appropriate position of the conduction band (CB) and valence band (VB) levels between P25 and BiOBr. Meanwhile, PFOA molecules were coordinated to the P25/BiOBr's surface via unidentate binding, being directly activated and oxidised by h , resulting in a decomposition yield of 99.5% (100 mg/L) under simulated solar light irradiation within 100 min, at the initial pH condition (3.5). A stepwise photodegradation pathway was proposed due to the significant intermediates detected as the short-chain perfluorinated carboxylic acids (C2-C7). Reactive oxygen species (ROS) generation, scavenging and trapping analysis indicated that the direct oxidation on h followed PFOA degradation. In a real aqueous environment of Tangxun lake (adjusted pH 3.5), stable common anions and natural organic matter (NOM) would restrain the PFOA photodegradation. However, adding 10 mg/L of NO or HA could reduce the inhibition effect of PFOA photodegradation. These findings gave an alternative strategy to drive an h directly oxidation to treat PFOA contaminated water bodies.