Vapor pressures, aqueous solubilities, and Henry's law constants of some brominated flame retardants



The subcooled liquid vapor pressures (P°L,25s) and aqueous solubilities (Sw,25s) were determined and Henry's law constants (H25s) were estimated for a number of brominated flame retardants (BFRs) at 25°C. The established methods of the gas chromatography-retention time and generator column techniques were used to experimentally determine Pmath image and Sw,25 for hexabromobenzene and a series of brominated diphenyl ether (BDE) congeners. The H25 was estimated as the ratio of Pmath image to the subcooled liquid aqueous solubility. Values of Pmath image obtained ranged from 0.000000282 Pa (BDE-190) to 0.259 Pa (BDE-3); Sw,25 ranged from 0.00000087 g/L (BDE-153 and BDE-154) to 0.00013 g/L (BDE-15); and H25 ranged from 0.0074 Pa m3/mol (BDE-183) to 21 Pa m3/mol (BDE-15). An increase in the bromine content of polybrominated diphenyl ether congeners resulted in significant decreases of Pmath image, Sw,25, and H25. A simple four-compartment equilibrium distribution model suggested that the majority of BFRs being released into the environment would reside in soil and sediment and have localized distributions. The model also suggested that lower brominated congeners tend to be somewhat more mobile. Degradative debromination reactions that yield these congeners would mobilize them environmentally, and ultimately affect the fate and distribution of BFRs.