Commercial steel wool used for Zero Valent Iron and as a source of dissolved iron in a combined red-ox process for pentachlorophenol degradation in tap water

Abstract

Abstract Pentachlorophenol solutions in tap water were treated with a combined process of zero valent iron (ZVI) reduction followed by a photo-Fenton oxidation. Commercial steel wool was used as ZVI source, demonstrating its effectivity for pentachlorophenol de-chlorination at acidic pH values. The reductive pathway was monitored by the use of excitation emission matrices, showing the transformation of the initial compound into the fluorescent species 4-chlorophenol and phenol. While the use of tap water represented a drawback in photo-Fenton oxidative reactions (at least half kinetic constants values) an improvement was achieved when the reductive stage was applied in the studied pH range. The transformation of pentachlorophenol into phenol produced an increase in oxidative stage rate of about 8 times. This fact could be related to the treatment time and hydrogen peroxide consumption of the photo-Fenton process, enhancing the economic viability. Furthermore, the de-chlorination of the pentachlorophenol minimized the possibility of releasing toxic by-products in the photo-Fenton process.