Photocatalytic degradation and mineralization of perfluorooctanoic acid (PFOA) using a composite TiO2 -rGO catalyst

Beatriz Gomez-Ruiz; Paula Ribao; Nazely Diban; Maria J Rivero; Inmaculada Ortiz; Ane Urtiaga

doi:10.1016/j.jhazmat.2017.11.048

Photocatalytic degradation and mineralization of perfluorooctanoic acid (PFOA) using a composite TiO₂ -rGO catalyst

J Hazard Mater. 2018 Feb 15:344:950-957. doi: 10.1016/j.jhazmat.2017.11.048. Epub 2017 Nov 28.

Authors

Beatriz Gomez-Ruiz¹, Paula Ribao¹, Nazely Diban¹, Maria J Rivero¹, Inmaculada Ortiz¹, Ane Urtiaga²

Affiliations

¹ Department of Chemical and Biomolecular Engineering, Universidad de Cantabria, Av. de Los Castros s/n, 39005 Santander, Spain.
² Department of Chemical and Biomolecular Engineering, Universidad de Cantabria, Av. de Los Castros s/n, 39005 Santander, Spain. Electronic address: urtiaga@unican.es.

PMID: 29197229
DOI: 10.1016/j.jhazmat.2017.11.048

Abstract

The inherent resistance of perfluoroalkyl substances (PFASs) to biological degradation makes necessary to develop advanced technologies for the abatement of this group of hazardous substances. The present work investigated the photocatalytic decomposition of perfluorooctanoic acid (PFOA) using a composite catalyst based on TiO₂ and reduced graphene oxide (95% TiO₂/5% rGO) that was synthesized using a facile hydrothermal method. The efficient photoactivity of the TiO₂-rGO (0.1gL^-1) composite was confirmed for PFOA (0.24mmolL^-1) degradation that reached 93±7% after 12h of UV-vis irradiation using a medium pressure mercury lamp, a great improvement compared to the TiO₂ photocatalysis (24±11% PFOA removal) and direct photolysis (58±9%). These findings indicate that rGO provided the suited properties of TiO₂-rGO, possibly as a result of acting as electron acceptor and avoiding the high recombination electron/hole pairs. The release of fluoride and the formation of shorter-chain perfluorocarboxilyc acids, that were progressively eliminated in a good match with the analysed reduction of total organic carbon, is consistent with a step-by-step PFOA decomposition via photogenerated hydroxyl radicals. Finally, the apparent first order rate constants of the TiO₂-rGO UV-vis PFOA decompositions, and the intermediate perfluorcarboxylic acids were found to increase as the length of the carbon chain was shorter.

Keywords: Graphene oxide; PFOA; Perfluorooctanoic acid; Photocatalysis; TiO(2)-rGO; Titanium dioxide.