Synergistically boosting sulfamerazine degradation via activation of peroxydisulfate by photocatalysis of Bi2O3-TiO2/PAC under visible light irradiation

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2022-01, Vol.428, p.132613, Article 132613
• Main Authors: Li, Jia-qi, Zhou, Zhi-wei, Li, Xing, Yang, Yan-ling, Gao, Jing-feng, Yu, Rui, Wang, Hui-ping, Wang, Nan
• Format: Article
• Language: English
• Subjects: Bi2O3-TiO2/PAC composite; Nonradical oxidation; Sulfamerazine degradation; Sulfate radical-advanced oxidation process
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2021.132613

[Display omitted] •Photocatalysis-activated PDS over Bi2O3-TiO2/PAC exhibited excellent SMZ degradation.•Synergistic mechanism of Vis, Bi2O3-TiO2/PAC and PDS was revealed.•Nonradical oxidation involved C = O groups and mediated electron transfer.•Applicability and effectiveness of Vis-Cata-PDS process were optimized and verified. Photocatalysis-activated sulfate-radical advanced oxidation process (SR-AOP) is an effective approach to remove organic micropollutants from water. Here, we tested a photocatalysis-activated SR-AOP in which peroxydisulfate (PDS) was activated by composites of Bi2O3-TiO2 photocatalyst supported onto commercial powdered activated carbon (Bi2O3-TiO2/PAC) under visible light irradiation. This “Vis-Cata-PDS” treatment exhibited outstanding degradation performance (97.96% removal) towards sulfamerazine (SMZ) following optimized reaction conditions of 0.1 g/L Bi2O3-TiO2/PAC and 0.1 g/L PDS at pH of 7. Synergistic effects were observed between the visible-light photocatalytic activation of PDS via direct electron transfer and nonradical PDS activation over pristine PAC within Bi2O3-TiO2/PAC. Both active radicals (SO4·−, h+, ·O2−) and nonradical singlet oxygen (1O2) and the mediated electron transfer of pristine PAC within Bi2O3-TiO2/PAC were contributed to SMZ degradation. Based on intermediates identified by Liquid Chromatograph-Mass Spectrometer (LC-MS) combined with density functional theory (DFT) calculations, three degradation pathways were proposed and that were mostly attributed to SO2 extrusion/Smiles-type rearrangement and S-N bond cleavage, and toxicity of intermediates were effectively alleviated. An inhibitory effect on SMZ degradation was observed for presence of HCO3−, whereas presence of SO42− was less inhibitory and Cl− had no effect. The Bi2O3-TiO2/PAC composite displayed excellent reusability and stability, and it was effective towards a number of tested micropollutants (sulfadiazine, sulfamethoxazole, ciprofloxacin, bisphenol A and methyl orange) and in real water matrixes. This work offers deep insights into the nonradical oxidation mechanism and application of Vis-Cata-PDS over a Bi2O3-TiO2/PAC composite for removal of organic micropollutants.