Photolytic decomposition of PFOS by electrospun nanofiber composites of Fe(III)/PVDF Under UV-C light

Abstract

Per- and polyfluoro alkyl substances (PFAS) are emerging pollutants that have contaminated various water streams of the world. Besides polluting the environment, it is related to several human diseases, including cancer. Various methods have been proposed to remove PFAS from water streams including, photocatalytic or photolytic decomposition of PFAS which decomposes PFAS in a quasi-perpetual fashion and does not generate secondary pollution. In this work, perfluoroctane sulfonic acid (PFOS) is used as a model PFAS to study its photolytic decomposition by nanofiber composites (NFC) of Fe (III) and polyvinylidene fluoride (PVDF) under ultraviolet (UV)-C light. The nanofiber composite was fabricated using an electrospinning technique with PVDF and iron precursor on the conductive surface of indium tin oxide (ITO) coated polyethylene terephthalate (PET) film. The composite was characterized with SEM-EDX, AFM, XRD, and TGA. It was found that a significant amount, 70 % of aqueous PFOS solution is decomposed by the composites in the presence of traces of hydrogen peroxide and UV-C light. The kinetics of PFOS degradation was fit with pseudo-first order rate constant of 0.056 hr−1. It is proposed that PFOS binds with Fe(III) to form an unstable complex that is decomposed under UV-C light and Fe(III) is reduced Fe(II). Hydrogen peroxide provides the simultaneous benefits of further decomposing the PFOS complex and regenerating Fe(III). The overall results suggest that this nanofiber composite can be used for the photolytic decomposition of PFOS. It is also revealed that two composite mats showed the optimal performance and the increase in concentration of hydrogen peroxide increased the degradation of PFOS monotonically.