| Volatilization | The Henry's Law constant for hexadecane is estimated as 21 atm-cu m/mole(SRC) derived from its vapor pressure, 0.00149 mm Hg(1), and water solubility, 2.1X10-5 mg/L(2). This Henry's Law constant indicates that hexadecane is expected to volatilize rapidly from water surfaces(3). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(3) is estimated as 4 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(3) is estimated as 6 days(SRC). However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column. The estimated volatilization half-life from a model pond is approximately 24 months if adsorption is considered(4). n-Hexadecane's estimated Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). Hexadecane is not expected to volatilize from dry soil surfaces based upon its vapor pressure(SRC).
Literature: (1) Daubert TE, Danner RP; Physical and Thermodynamic Properties of Pure Dhemicals: Data Compilation. Design Institute for Physical Property Data, American Institute of Chemical Engineers. Taylor & Francis, Washington, DC (1999) (2) Coates M et al; Environ Sci Technol 19: 628-32 (1985) (3) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 15-1 to 15-29 (1990) (4) US EPA; EXAMS II Computer Simulation (1987) |
| Soil Adsorption | Using a structure estimation method based on molecular connectivity indices(1), the Koc of hexadecane can be estimated to be 53,000(SRC). According to a classification scheme(2), this estimated Koc value suggests that hexadecane is expected to be immobile in soil(SRC). From the experimental value of Freundlich adsorption constants and organic carbon contents in three Canadian soils (Wendover 16.2% OC; Vaudreil 10.0% OC; Grimsby 1.0% OC)(3), Koc values can be estimated to be in the range of approximately 50-400(SRC). The experimental data of other investigators suggest that less than 20% of hexadecane from solution is adsorbed in soil, sludge and sediment(4-6). However, in all the adsorption experiments(3-6), the concentration of hexadecane solution used for the adsorption study far exceeded the aqueous solubility of hexadecane making the results questionable(SRC).
Literature: (1) US EPA; Estimation Program Interface (EPI) Suite. Ver. 4.11. Nov, 2012. Available from, as of Nov 17, 2015: http://www2.epa.gov/tsca-screening-tools (2) Swann RL et al; Res Rev 85: 23 (1983) (3) Nathwani JS, Phillips CR; Chemosphere 6: 157-62 (1977) (4) Meyers PA, Quinn JG; Nature 244: 23-4 (1973) (5) Kanatharana P, Grob RL; J Environ Sci Health A18: 59-77 (1985) (6) Lee RF; pp. 611-6 in Proc 1977 Oil Spill Conf. New Orleans, LA: American Petroleum Institute (1977) |
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