Partitioning of Fluorotelomer Alcohols to Octanol and Different Sources of Dissolved Organic Carbon
2008-09-01T00:00:00Z (GMT) by
Interest in the environmental fate of fluorotelomer alcohols (FTOHs) has spurred efforts to understand their equilibrium partitioning behavior. Experimentally determined partition coefficients for FTOHs between soil/water and air/water have been reported, but direct measurements of partition coefficients for dissolved organic carbon (DOC)/water (<i>K</i><sub>doc</sub>) and octanol/water (<i>K</i><sub>ow</sub>) have been lacking. Here we measured the partitioning of 8:2 and 6:2 FTOH between one or more types of DOC and water using enhanced solubility or dialysis bag techniques, and also quantified <i>K</i><sub>ow</sub> values for 4:2 to 8:2 FTOH using a batch equilibration method. The range in measured log <i>K</i><sub>doc</sub> values for 8:2 FTOH using the enhanced solubility technique with DOC derived from two soils, two biosolids, and three reference humic acids is 2.00−3.97 with the lowest values obtained for the biosolids and an average across all other DOC sources (biosolid DOC excluded) of 3.54 ± 0.29. For 6:2 FTOH and Aldrich humic acid, a log <i>K</i><sub>doc</sub> value of 1.96 ± 0.45 was measured using the dialysis technique. These average values are ∼1 to 2 log units lower than previously indirectly estimated <i>K</i><sub>doc</sub> values. Overall, the affinity for DOC tends to be slightly lower than that for particulate soil organic carbon. Measured log <i>K</i><sub>ow</sub> values for 4:2 (3.30 ± 0.04), 6:2 (4.54 ± 0.01), and 8:2 FTOH (5.58 ± 0.06) were in good agreement with previously reported estimates. Using relationships between experimentally measured partition coefficients and C-atom chain length, we estimated <i>K</i><sub>doc</sub> and <i>K</i><sub>ow</sub> values for shorter and longer chain FTOHs, respectively, that we were unable to measure experimentally.