Mechanisms of Co-catalytic action of humic-like additives on pentachlorophenol oxidation by a Fe-porphyrin catalyst

Abstract

Gallic acid (3,4,5-trihydroxybenzoic acid, GA) which is a key component of humic acids in combination with imidazole affects the catalytic performance of pentachlorophenol (PCP) decomposition by a Fe-porphyrin catalyst via diverse mechanisms. GA can improve drastically the yield and the kinetics of the catalytic oxidation of PCP by a factor of 20. In the presence of GA, imidazole acts competitively with PCP consuming oxidative equivalents. The data of catalytic oxidation products indicate a mechanism where decomposition of PCP occurs through oxidative dechlorination, initialized by an oxo-ferryl porphyrin π-cation radical complex formed on the Fe-porphyrin catalyst.