Photoelectrochemical activation of free chlorine utilizing vacancies-engineered BiVO4 photoanode for simultaneous pharmaceuticals and personal care products (PPCPs) degradation and bacterial inactivation: An integrative batch and continuous flow reactor study

• Published in: Separation and purification technology 2025-07, Vol.360, p.130959, Article 130959
• Main Authors: Man, Justin H.K., Zheng, Zexiao, Dong, Taoran, Lung, Cheuk Wai, Cheung, Howard Y.M., Wang, Xiaoying, Dong, Haoran, Guan, Xiaohong, Lo, Irene M.C.
• Format: Article
• Language: English
• Subjects: Continuous flow photoelectrochemical reactor; Disinfection; Pharmaceuticals and personal care products; Photoelectrochemical chlorine activation; Photoelectrochemical water treatment
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.130959

[Display omitted] •The PEC/chlorine system achieves superior PPCP degradation and E. coli inactivation.•VBi,O-BiVO4 photoanodes suppress charge recombination and avoid secondary pollution.•The PEC/chlorine system reduces DBP generation compared with PC/chlorine.•OH and OCl dominate PPCP degradation by the e−/h+-inducing chlorine activation.•The designed continuous flow reactor shows outstanding practicality of the system. Conventional water treatment plants are found to be incapable of degrading pharmaceuticals and personal care products (PPCPs), thereby imposing high risks to human health. As a solution to the deficiency of conventional water treatment plants, although the photocatalysis (PC)/chlorine process has been demonstrated to be feasible for incorporating PPCP degradation and disinfection, its development has been limited by the rapid recombination of charge carriers, secondary pollution, and intense formation of disinfection byproducts (DBPs). To overcome these limitations of the PC/chlorine process, we have developed a novel photoelectrochemical (PEC)/chlorine system with enhanced charge separation forced by external bias in this study. A dual-vacancy-engineered BiVO4 (VBi,O-BiVO4) photoanode with improved PEC properties was synthesized for the PEC/chlorine system, which can prevent secondary disinfection by immobilizing the photocatalyst. The effectiveness of the PEC/chlorine system is shown by achieving an enhanced carbamazepine (CBZ, a PPCP) degradation rate constant of 0.065 min−1 (compared with 0.041 min−1 for the PC/chlorine system) and complete inactivation of 3-log/mL E. coli within 1 min in a batch reactor. The mechanistic study reveals that both photogenerated electrons and holes engage in chlorine activation, producing OH and OCl as the predominant reactive species for PPCP degradation. Notably, compared to the PC/chlorine process, the PEC/chlorine system reduces DBP formation by 44.6 %, ensuring the safety of the treated water. Furthermore, the scalability of the PEC/chlorine system from a batch to continuous flow reactor is proven by achieving excellent performance in PPCP degradation and E. coli disinfection with a low power-intensive UV light source. This study provides detailed insights into the potential applications of the PEC/chlorine process for PPCP degradation and disinfection in future water treatment processes.