Abstract
Photodegradation in the absence of externally added chemicals could be an attractive solution for the removal of perfluorooctane sulfonate (PFOS) in aqueous environment, but the low decomposition rate presents a severe challenge and the underlying mechanisms are unclear. In this study, we demonstrated that PFOS could be effectively degraded in a catalyst-free aqueous solution via a reduction route. Under appropriate pH and temperature conditions, a rapid PFOS photodegradation, with a pseudo-first-order decomposition rate constant of 0.91 h−1, was achieved. In addition, hydrated electrons were considered to be the major photo-generated reductive species responsible for PFOS photodegradation in this system. Its production and reduction ability could be significantly affected by the environmental conditions such as pH, temperature and presence of oxidative species. This study gives insights into the PFOS photodegradation process and may provide useful information for developing catalyst-free photodegradation systems for decomposing PFOS and other persistent water contaminants.
Highlights
Photodegradation in the absence of externally added chemicals could be an attractive solution for the removal of perfluorooctane sulfonate (PFOS) in aqueous environment, but the low decomposition rate presents a severe challenge and the underlying mechanisms are unclear
Photodegradation without chemical-dosing in aqueous solution is a promising process to treatment PFOS, but a low degradation efficiency presents a severe limitation at the present stage[10,13]
This study attempts to find out the reason behind such a slow PFOS degradation
Summary
Photodegradation in the absence of externally added chemicals could be an attractive solution for the removal of perfluorooctane sulfonate (PFOS) in aqueous environment, but the low decomposition rate presents a severe challenge and the underlying mechanisms are unclear. We demonstrated that PFOS could be effectively degraded in a catalyst-free aqueous solution via a reduction route. P erfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) have been widely used in the industrial production sectors over decades, due to their excellent thermal, chemical stability and surface activity[1]. They are environmentally persistent and bio-accumulative[2,3], and have high developmental toxicity, immunotoxicity, and hepatotoxicity[4,5,6]. This study aims to shed light on the photodegradation process of PFOS in a catalyst-free aqueous solution and elucidate the underlying mechanisms. The findings in this study may provide useful information and guidance for future optimization of PFOS photodegradation processes
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