Ethanol

CAS RN: 64-17-5

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), a log Koc value of 0.20(2), indicates that ethanol is expected to have very high mobility in soil. Volatilization of ethanol from moist soil surfaces is expected(SRC) given a Henry's Law constant of 5.0X10-6 atm-cu m/mole(3). Ethanol is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 59.3 mm Hg at 25 deg C(4). Ethanol, present at 100 mg/L, reached 89% of its Theoretical BOD in 2 weeks using an activated sludge inoculum at 30 mg/L in the Japanese MITI test(5). Ethanol, present at 100 mg/L, was completely degraded in 5-8 days in an aerobic sandy soil/groundwater microcosm(6).
AQUATIC FATE: Based on a classification scheme(1), a log Koc value of 0.20(2), indicates that ethanol is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon a Henry's Law constant of 5.0X10-6 atm-cu m/mole(4). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 5 and 39 days, respectively(SRC). Ethanol is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(3). According to a classification scheme(5), an estimated BCF of 3(SRC), from its log Kow of -0.31(6) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is low. Biodegradation of ethanol in water is expected based on degradation half-lives on the order of a few days in aquatic studies conducted using microcosms constructed with a low organic sandy soil and groundwater(8).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), ethanol, which has a vapor pressure of 59.3 mm Hg at 25 deg C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase ethanol is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 5 days(SRC), calculated from its rate constant of 3.27X10-12 cu cm/molecule-sec at 25 deg C(3). Ethanol does not contain chromophores that absorb at wavelengths >290 nm(4) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).
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