Visible and UV photocatalysis of aqueous perfluorooctanoic acid by TiO2 and peroxymonosulfate: Process kinetics and mechanistic insights. (March 2020)

• Record Type: Journal Article
• Authors: Xu, Bentuo; Ahmed, Mohammad Boshir; Zhou, John L.; Altaee, Ali
• Is Part Of: Chemosphere. Volume 243(2020)
• Publication Date: 2020-03
• Subjects: Perfluorooctanoic acid -- Peroxymonosulfate -- Photocatalysis -- Sulfate radicals -- Visible light; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2019.125366
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The global occurrence and adverse environmental impacts of perfluorooctanoic acid (PFOA) have attracted wide attention. This study focused on the PFOA photodegradation by using photocatalyst TiO2 with peroxymonosulfate (PMS) activation. Aqueous PFOA (50 mg L −1 ) at the pH 3 was treated by TiO2/PMS under 300 W visible light (400–770 nm) or 32 W UV light (254 nm and 185 nm). The addition of PMS induced a significant degradation of PFOA under powerful visible light compared with sole TiO2 . Under visible light, 0.25 g L −1 TiO2 and 0.75 g L −1 PMS in the solution with the initial pH 3 provided optimum condition which achieved 100% PFOA removal within 8 h. Under UV light irradiation at 254 nm and 185 nm wavelength, TiO2 /PMS presented excellent performance of almost 100% removal of PFOA within 1.5 h, attributed to the high UV absorbance by the photocatalyst. The intermediates analysis showed that PFOA was degraded from a long carbon chain PFOA to shorter chain intermediates in a stepwise manner. Furthermore, scavenger experiments indicated that SO 4 – radicals from PMS and photogenerated holes from TiO2 played an essential role in degrading PFOA. The presence of organic compounds in real wastewater reduced the degradation efficacy of PFOA by 18–35% in visible/TiO2 /PMS system. In general, TiO2 /PMS could be an ideal and effective photocatalysis system for the degradation of PFOA from wastewater using either visible or UV light source. Graphical abstract: Image 1 Highlights: 100% PFOA was degraded within 9 h by TiO2 /PMS under visible light. 1.3:1 molar ratio of TiO2 /PMS was optimum for PFOA degradation. SO 4 – and photoinduced holes were the main active species. 100% PFOA in real wastewater was degraded within 2 h under UV light.