Photochemistry of 2,2', 4,4', %,5'-hexabde (BDE-153) in THF and adsorbed on SiO2: first observation of OH reactivity of BDEs on aerosol

BDE-153 (2,2',4,4',5,5'-hexabromo diphenylether) is a component of the flame retardant mixtures penta- and octaBDE and a trace constituent of decaBDE. Furthermore, it may occur as a minor intermediate in the photolysis of decaBDE. We have previously studied the UV spectrum and quantum yield for the photolysis of BDE-153 in tetrahydrofuran (THF) solution3, and we now present a comparison of the photolytic degradation pathways of this symmetrical molecule in solution and adsorbed at sub-monlayer thickness on aerosol particles, made of fused silica (Aerosil 380), in an aerosol smog chamber facility. Furthermore, the aerosol smog chamber technique allows us to expose aerosol-borne compounds to OH radicals, which are known to clean the atmosphere efficiently from air pollutants. Atmospheric residence times of air pollutants can then be assessed from the rate constants for the reaction with OH radicals, and a first, preliminary result on BDE-153 + OH will be presented.