Study of the reactions between tetrabromobisphenol A and PbO and Fe2O3 in inert and oxidizing atmospheres by various thermal methods

• Mechanism of bromination reaction in TBBPA + PbO and TBBPA + Fe2O3 mixtures.
• Fate of Pb and Fe studied in inert and oxidizing atmospheres by thermal techniques.
• Catalytic effect of PbO and Fe2O3 on TBBPA decomposition by TG–MS method.

DSC, TG, and TG–MS techniques were used to investigate the reactivity of PbO and Fe2O3 with HBr from thermal degradation of tetrabromobisphenol A under inert and oxidizing atmospheres. The HBr acted as an excellent brominating agent for PbO and separated Pb as a volatile bromide (79 and 90% in He and He + 5 vol% O2, respectively) from the solid up to 580 °C. For Fe2O3, the amount of vaporized bromide was only 20 and 13% under inert and oxidizing atmospheres, respectively. In inert atmosphere the formed char acted as a reducing agent for converting the remaining oxides into metallic forms. For TBBPA + PbO, about 3% of metallic Pb remained in the residue as most of the oxide vaporized below 970 °C. The unreacted Fe2O3 underwent progressive reduction into metallic Fe (75%), which remained in the residue. In oxidizing atmosphere, the unreacted PbO vaporized completely, while the Fe2O3 remained unchanged in the residue. The organic char decomposed and vaporized as carbon mono- and di-oxides. Simultaneous TG–MS measurements indicated that the presence of PbO and Fe2O3 strongly accelerated TBBPA degradation and enhanced char formation.