Spectroscopic behavior of saytex 8010 under UV-visible light and comparative thermal study with some flame bromine retardant

• The decabromodiphenyl ethane (DBDPE/saytex 8010) is photolytically unstable in THF after a very short time.
• The effect of irradiation on decabromodiphenyl ethane (DBDPE/saytex 8010) as a solid powder has been well clarified using thermogravimetric analysis.
• The similarity of behaviors of both substances under UV–visible irradiation and thermal conditions, we urge us to deeply study their toxicological effects.

Decabromodiphenyl ethane (DBDPE; saytex 8010) is a replacement for the flame retardant chemical decabromodiphenyl ether (DBDPO; saytex 102E), and has been reported in the environment. The photolytic degradation of DBDPE was investigated in tetrahydrofuran solvent (THF) as well as in solid state phase under artificial ultraviolet–visible light using UV–visible spectroscopy and thermal analysis via differential scanning calorimetry (DSC), thermogravimetry analysis (TGA) and derivative thermogravimetry (DTG) monitoring. The degradation kinetic of DBDPE in THF seems to be a very fast reaction. High photolytic efficiency i.e. 63.18% has been achieved within the first 180 s of irradiation time. The experimental data were well described by the pseudo first order kinetic model with high regression coefficient (R2 = 0.9373). The thermal behavior of the irradiated powder of DBDPE for 2 h 30 min differs substantially compared with that of no irradiated DBDPE. The maximum degradation rate of no irradiated powder of DBDPE occurs at Td = 423.82 °C with 99.80% loss of weight and nearly of 0% of char residue was achieved at T = 600 °C. However, the melting temperature of the irradiated powder of DBDPE for 2 h 30 min reduces by about 46.91 °C, the weight loss ratio of DBDPE is about 11% and the maximum degradation rate at the maximum weight loss ratio decreases by about 54.30 °C. The onset and the maximum degradation rate were also assessed at 5% for different Albemarle flame retardants for comparison reason. Under inert atmosphere, the degradation of DBDPE and DBDPO fellow one stage and the melting temperature of DBDPE and DBDPO are located at T = 351.22 °C and T = 304.01 °C, respectively. The degradation of each ones is achieved with any residue. However, the thermal degradation of saytex HP800A begins at much lower temperature, whereas saytex BT93 shows slightly enhanced thermal stability and their thermal degradation occurred through two steps. When the temperature reached T = 680 °C, almost decomposed and 18.00% and 19.67% char residue were obtained for saytex BT93 and saytex HP800A, respectively. The degradation involves the formation of subsequently less bromine substituted congeners of DBDPE within the irradiation time. Further research is required to understand the photolytic degradation pattern of DBDPE and to facilitate the design of remediation processes as well as help to predict their fate in the environment.