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Gallic acid mediated oxidation of pentachlorophenol by the Fenton reaction under mild oxidative conditions
Author(s) -
Christoforidis Konstantinos C,
Vasiliadou Ioanna A,
Louloudi Maria,
Deligiannakis Yiannis
Publication year - 2018
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.5529
Subject(s) - pentachlorophenol , chemistry , electron paramagnetic resonance , redox , radical , catalysis , gallic acid , degradation (telecommunications) , decomposition , reaction mechanism , chelation , hydroxyl radical , inorganic chemistry , nuclear chemistry , photochemistry , antioxidant , organic chemistry , telecommunications , physics , nuclear magnetic resonance , computer science
BACKGROUND The present study demonstrates the decomposition of pentachlorophenol (PCP) by the Fenton reaction in the presence of gallic acid (GA). Unlike other studies, catalytic Fe 2+ concentrations were used with respect to PCP in an effort to evaluate an environmentally benign Fenton system, studying the effect of phenolic‐type compounds widely found in the environment. The effect of operating variables was evaluated. RESULTS At initial reaction times or at low H 2 O 2 and Fe concentrations, GA enhanced PCP removal. At high H 2 O 2 and Fe concentrations GA enhanced PCP removal only at initial reaction times. GA was the determinant factor controlling activity acting both as a chelating agent and reducer of Fe 3+ . Electron paramagnetic resonance (EPR) spectroscopy was applied to shed light on mechanistic aspects, verifying the interaction of GA with Fe ions. GA accelerated significantly the Fe 3+ /Fe 2+ redox cycling. This enhanced the formation of hydroxyl radicals (HO · ) as confirmed by in situ EPR spin trap experiments. A reaction mechanism was proposed including the redox cycle of GA quinoide forms. CONCLUSION The operational variables of a GA modified Fenton system are provided and mechanistic steps are discussed including PCP degradation, GA/Fe interaction, Fe 3+ /Fe 2+ redox cycling and HO · formation. GA concentration controls the catalytic degradation of PCP. © 2017 Society of Chemical Industry