2D nanosheet CoOx/BiVO4 heterojunction for promoting peroxysulphate activation: Performance and mechanistic

Abstract

Bisphenol A (BPA) is an emerging organic pollutant that can disturb endocrine systems at trace levels in water. This study constructed a photocatalyst of cobalt oxide modified bismuth vanadate (CoOx/BiVO4) coupled with peroxymonosulfate (PMS) oxidation system to investigate its photocatalytic mechanism for degrading BPA in wastewater. The CoOx/BiVO4 photocatalyst was fabricated through a precipitation-hydrothermal method and systematically characterized. The results showed that modifying BiVO4 with CoOx significantly improved the separation and migration efficiency of photogenerated electron–hole pairs, thereby enhancing the photocatalytic activity of the system. Through active species trapping experiments using different scavengers, singlet oxygen (1O2) and sulfate radicals (SO4−⋅) were identified as the predominant reactive oxygen species responsible for BPA degradation. BPA photocatalytic reaction intermediates were analyzed using HPLC-MS, which proposed three possible degradation pathways: (1) Initial hydroxylation of BPA by SO4−⋅ and ⋅OH radicals; (2) Ring-opening oxidation of hydroxylated intermediates into carboxylic acids; (3) Further mineralization of all intermediates into CO2 and H2O by 1O2 and ⋅OH. In summary, the CoOx/BiVO 4-PMS system provides an efficient and promising technology for eliminating trace BPA in wastewater via synergistic effects of SO4−⋅ and 1O2. Further optimization of CoOx loading and PMS dosage is still needed to maximize the overall photocatalytic performance.