Isopropanol

CAS RN: 67-63-0

Volatilization

The Henry's Law constant for isopropanol is 8.10X10-6 atm-cu m/mole at 25 deg C(1). This Henry's Law constant indicates that isopropanol is expected to volatilize from water surfaces(2). 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)(2) is estimated as 86 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)(2) is estimated as 29 days(SRC). Isopropanol's Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). Isopropanol is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 45.2 mm Hg at 25 deg C(3). The volatilization of isopropanol from a runoff tank of an industrial wastewater treatment facility was measured; the volatilization rate of isopropanol ranged between 0.64-0.69 mg/sq m-min(4). The evaporation rate of a 1:1 isopropanol:water mixture from a shallow pool was 1.5 kg/sq-m per hour at a wind speed of 4.5 m/s and pool temperature of 20 deg C and an ambient air temperature of 22 deg C(5). Laboratory studies demonstrated that isopropanol will volatilize from water to air in the absence of wind(6).
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