The compounds 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), hexabromobenzene (HBB), pentabromobenzene (PBB), 2-ethylhexyl 2,3,4,5-tetrabenzoate (TBB), and bis(2-ethylhexyl) tetrabromophthalate (TBPH) are among a group of novel brominated flame retardants that have replaced polybrominated diphenyl ethers (PBDEs). To date, most of the physicochemical and partitioning properties of these compounds have been estimated based upon their structures using various linear free energy relationships and these values have yet to be corroborated by experimental data. For this study, we measured the aqueous solubility, n-octanol-water (KOW), and dissolved organic carbon partition coefficients (KDOC) for these five novel brominated flame retardants. Measurements were conducted using batch equilibrium approaches and compared to values estimated using both single and poly parameter LFERs. DOM used in this study included both an International Humic Substances Society reference material (Suwannee River Natural Organic Matter) and organic matter isolated from the Arctic. We observed Suwannee River KDOC values for BTBPE, HBB, and PBB of 58000 L/kg, 42000 L/kg, and 10000 L/kg, respectively. These values roughly correspond to their hydrophobicity. The aqueous solubilities for BTBPE, HBB, and PBB were observed to be 5.1nM, 3.4nM, and 25.0nM, respectively. Work is ongoing to determine the remaining aqueous solubilities, octanol-water partition coefficients, and KDOC values, as well as how they compare to LFER estimated values.

Physicochemical and dissolved organic matter partitioning properties of novel brominated flame retardants

ACS Spring 2022

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