| Volatilization | The Henry's Law constant for formaldehyde is 3.37X10-7 atm-cu m/mole(1). This Henry's Law constant indicates that formaldehyde is expected to be essentially nonvolatile from water surfaces(2). Formaldehyde's Henry's Law constant indicates that volatilization from moist soil surfaces is not expected to be an important fate process(SRC). Formaldehyde is a gas under ambient conditions(3), therefore, volatilization from dry soil surfaces will occur(SRC).
Literature: (1) Betterton EA, Hoffmann MR; Environ Sci Technol 22: 1415-8 (1988) (2) Lyman WJ et al; Handbook of Chemical Property Estimation Methods. Washington, DC: Amer Chem Soc pp. 15-1 to 15-29 (1990) (3) Boublik T et al; The Vapor Pressures of Pure Substances. Vol. 17. Amsterdam, The Netherlands: Elsevier Sci. Publ p. 44 (1984) |
| Soil Adsorption | The Koc of formaldehyde is estimated as 8(SRC), using a log Kow of 0.35(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that formaldehyde is expected to have very high mobility in soil(SRC). Formaldehyde gas adsorbs on clay minerals to a degree at high gas concentrations which is an important quality in its use as a soil fumigant(4). In addition, formaldehyde may interact with humic substances in soil(5) resulting in decreased mobility.
Literature: (1) Hansch C et al; Exploring QSAR. Hydrophobic, Electronic, and Steric Constants. ACS Prof Ref Book. Heller SR, consult. ed., Washington, DC: Amer Chem Soc p. 3 (1995) (2) US EPA; Estimation Program Interface (EPI) Suite. Ver. 4.11. Nov, 2012. Available from, as of Dec 23, 2014: http://www.epa.gov/oppt/exposure/pubs/episuitedl.htm (3) Swann RL et al; Res Rev 85: 17-28 (1983) (4) De SK, Chandra K; Sci Cult 44: 462-4 (1978) (5) Cooke CM et al; Bull Environ Contam Toxicol 70: 761-8 (2003) |
| Vapor Pressure | | Pressure | Reference |
|---|
| 3,890 mm Hg at 25 deg C /100% formaldehyde/ | Boublik, T., Fried, V., and Hala, E., The Vapour Pressures of Pure Substances. Second Revised Edition. Amsterdam: Elsevier, 1984., p. 44 |
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