Pattern of oxidation products derived from tetrabromobisphenol A in a catalytic system comprised of iron(III)-tetrakis(p-sulfophenyl)porphyrin, KHSO5 and humic acids

Abstract

Tetrabromobisphenol A (TBBPA), a commercially used brominated flame retardant, also functions as an endocrine disruptor and is of serious concern in terms of environmental pollution. TBBPA has been detected in leachates from landfills, because hydrophobic interactions with humic acids (HAs) result in an increase in its solubility. In the present study, the oxidation of TBBPA was examined using a biomimetic catalytic system comprised of a combination of iron(III)-tetrakis(p-sulfophenyl)porphyrin (FeTPPS) and KHSO5. Although more than 90% of TBBPA was oxidized at pH 8 in the absence and presence of HAs, no debromination was observed. An analysis of the oxidation products by GC/MS indicated that 4-(2-hydroxyisopropyl)-2,6-dibromophenol was the main byproduct. However, only about 6–12% of the TBBPA was degraded. In the presence of HAs, the remaining byproducts from TBBPA may be incorporated into HAs via a variety of interactions. Thus, HA fractions in the reaction mixture were separated, and analyzed for their Br content. Based on the analyses, the majority of the Br species (70–80%) were found to be incorporated into HAs after oxidation with TBBPA. In addition, coupling compounds between brominated intermediates from TBBPA and phenolic moieties in HAs were detected by pyrolysis–GC/MS. These results lead to the conclusion that the oxidation of TBBPA in the presence of HAs via catalytic oxidation using FeTPPS resulted in the incorporation of brominated intermediates into the polymeric structures of HAs.