Acetic Acid (alias of Vinegar acid)

CAS RN: 64-19-7

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an experimentally derived Koc value of 1.0(2,3), indicates that acetic acid is expected to have very high mobility in soil(SRC). No detectable sorption was measured for acetic acid using the OECD Guideline 106 method in three different soils(4). The pKa of acetic acid is 4.76(5), indicating that this compound will exist predominantly in anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(6). Volatilization of acetic acid from moist soil surfaces is not expected to be an important fate process(SRC) given a Henry's Law constant of 1.43X10-7 atm-cu m/mole(7). Acetic acid is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 15.7 mm Hg at 25 deg C(8). Using a modified Organization of Economic Cooperation and Development (OECD) protocol, 75% degradation was reported in 14 days using garden soil as an inoculum(9), indicating that biodegradation is an important environmental fate process in soil(SRC).
AQUATIC FATE: Based on a classification scheme(1), a Koc value of 1.0(2,3), indicates that acetic acid is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(4) based upon a Henry's Law constant of 1.43X10-7 atm-cu m/mole(5). The pKa of acetic acid is 4.76(6), indicating that this compound will exist predominantly in anion form at an environmental pH range of 5-9. According to a classification scheme(7), an estimated BCF of 3(SRC), from its log Kow of -0.71(8) and a regression-derived equation(9), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Hydrolysis is not expected to be an important environmental fate process(SRC) since this compound lacks functional groups that hydrolyze under environmental conditions(4). Utilizing the Japanese MITI test, a 74% of theoretical BOD in 2 weeks using activated sludge(10) indicates that biodegradation is an important environmenal fate process in water(SRC).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), acetic acid, which has a vapor pressure of 15.7 mm Hg at 25 deg C(2), is expected to exist solely as a vapor in the ambient atmosphere. The pure compound is a solid below 68 deg F(3). Particulate-phase acetic acid will be removed from the atmosphere by wet and dry deposition. Vapor-phase acetic acid 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 22 days(SRC), calculated from its measured rate constant of 7.4X10-13 cu cm/molecule-sec at 25 deg C(4). Particulate-phase acetic acid will be removed from the atmosphere by wet and dry deposition. Acetic acid does not absorb light with wavelengths >290 nm(5) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC). Acetic acid occurs in rainwater, cloud water and fog(6-8) and can be removed from the atmosphere by wet deposition(SRC).
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