Octanol-Air Partitioning Coefficients

One problem with the use of pL as a key parameter in both adsorption and absorption is the difficulty in obtaining accurate values for pL for solid SOCs, since they are not experimentally accessible and must be estimated (e.g., see Finizio et al., 1997, and references therein). In addition, as discussed in the preceding section with respect to absorption into a liquid phase, slopes of 1 for plots of log Kp against log pL are only expected if the activity coefficients, y, do not change along a series of compounds. 

An alternate approach has been proposed that avoids the use of pL and introduces a ratio of activity coefficients rather than an absolute, single value. The advantage in terms of the activity coefficients is that the ratio 

The relationship between and KOA can be readily developed based on thermodynamic principles (e.g., see Finizio et al., 1997) see Box 9.4. 

gives the relationship between pL and the octanol-air partitioning coefficient, KOA. Rearranging Eq. (NNN) to obtain an expression for pL and substitution into Eq. (JJJ) give (Finizio et al., 

FIGURE 9.64 Plot of logKp for 10 PAHs in ambient air samples collected at seven sites worldwide as a function of calculated values of log KI)A. FLE fluorene, PH phenanthrene, AN anthracene, PY pyrene, FL fluoranthene, BaA benz a anthracene, CHR chrysene, BaP benzo a pyrene, BeP benzo e pyrene, BkF benzo k fluoranthene (adapted from Finizio ei al., 1997). 

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Finizio A, Mackay D, Bidleman T, Hamer T (2007) Octanol-air partition coefficient as a predictor of partitioning of semi-volatile organic chemicals to aerosols. Atmospheric Environment 31 2289-2296... 

Hamer, T. and Bidleman, T.F. (1996) Measurements of octanol-air partition coefficients for polychlorinated biphenyls. J. Chem. Eng. Data 41, 895-899. 

Hamer T. and Mackay, D. (1995) Measurement of octanol-air partition coefficients for chlorobenzenes, PCBs, and DDT. Environ. Sci. Technol. 29, 1599-1606. 

Shoeib, M., Harner,T. (2002) Using measured octanol-air partition coefficients to explain environmental partitioning of organochlorine pesticides. Environ. Toxicol. Chem. 21,984-990. 

Su,Y., Lei, D.L. Daly, G.,Wania, F. (2002) Determination of octanol-air partition coefficient (KqA) values for chlorobenzenes and polychlorinated naphthalenes from gas chromatographic retention times. J. Chem. Eng. Data, 47, 449 455. 

Reported Henry s law constants and octanol-air partition coefficients of n-pentane at various temperatures and temperature dependence equations... 

Octanol/Air Partition Coefficient, log KqA at 25°C or as indicated. Additional data at other temperatures designated are compiled at the end of this section ... 

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