Pyrolysis kinetics of tetrabromobisphenol a (TBBPA) and electric arc furnace dust mixtures

This work assesses the decomposition kinetics and the overall pyrolysis behavior of Tetrabromobisphynol A (TBBPA) mixed with Electric Arc Furnace Dust (EAFD) using experimental data from thermogravimetric analysis (TGA). Mixtures of both materials with varying EAFD:TBBPA ratios (1:1, 1:2, 1:3 and 1:4) were pyrolyzed in an inert atmosphere under dynamic heating conditions at different heating rates (5, 10, 30 and 50 °C/min). The pyrolysis of pure TBBPA proceeded through two decomposition steps: debromination and volatilization of debromination products. This is followed by char formation that also involves release of volatile organic matter. However, the pyrolysis of EAFD:TBBPA mixture proves to be more complex in nature due to the occurrence of parallel solid-liquid reactions that result in the release of HBr and other volatile organic compounds (VOC) coupled with bromination of metal oxides. Subsequent chemical events encompass evaporation of metal bromides and finally reduction of the remaining metal oxides, most notably iron oxide, into their metallic form by the char. Three models, namely, Kissinger, Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS), were deployed to derive kinetics parameters. Generally, it was found that the presence of EAFD has led to an increase in the apparent activation energy for the first stage of TBBPA decomposition due to the reduced evaporation of TBBPA.