Monopersulfate oxidation of tetrabromobisphenol A by an iron(III)-phthalocyaninetetrasulfate catalyst coordinated to imidazole functionalized silica particles

An iron(III)-phthalocyaninetetrasulfate (FePcTS) was axially coordinated to a series of imidazole functionalized silica, 3-(1-imidazolyl)propylcarbamoyl-3'-aminopropylsilica (IPS) particles. Among the prepared FePcTS/IPS catalysts, catalytic activity for the oxidation of tetrabromobisphenol A (TBBPA) for the smallest sized particle (<30 mu m) was more effective than larger sizes (145 mu m< and 45-145 mu m). The catalytic activity of FePcTS/IPS was compared with that of a structural analogue, iron(III)-tetrakis(p-sulfonatephenyl)porphyrin (FeTPPS) supported IPS (FeTPPS/IPS). The TOF values for the oxidation of TBBPA by FePcTS/IPS (11-17 h(-1)) were much larger than the corresponding values for FeTPPS/IPS (0.7-3.5 h(-1)) in the absence and presence of humic acid, a major coexistent substance in landfill leachates. To investigate the reasons for the differences in catalytic activities between the FePcTS and FeTPPS systems, the influence of ethanol, a SO4 center dot- scavenger, on the oxidation of TBBPA oxidation was tested. The TOF values for FePcTS/IPS decreased with increasing ethanol concentration, while the catalytic activities for FeTPPS/IPS were not affected by adding ethanol. These results suggest that the higher catalytic activity of the FePcTS catalytic system can be attributed to the contribution of radical species, which can be generated via the homolysis of O-O bonding in the Fe(III)-peroxo species. (C) 2015 Elsevier B.V. All rights reserved.