Dimethyl Sulfoxide

CAS RN:67-68-5

Volatilization

The Henry's Law constant for dimethyl sulfoxide is 1.03X10-8 atm-cu m/mole at 25 deg C(SRC) based upon a measured air/water partition coefficient equation of 136,600-1570T where T is in deg C and the partition coefficient is in mol/kg-atm(1). This Henry's Law constant indicates that dimethyl sulfoxide is expected to be essentially nonvolatile from moist soil and water surfaces(2). The observation that the concentration of dimethyl sulfoxide in marine air is about 1/100 that of dimethyl sulfide suggests that little or no dimethyl sulfoxide is volatilizing from the sea surface(3). Dimethyl sulfoxide's Henry's Law constant indicates that volatilization from moist soil surfaces is not expected to be an important(SRC). Dimethyl sulfoxide is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure 0.60 mm Hg at 25 deg C(4).
The volatilization rate of a pool of dimethyl sulfoxide was measured at 0 and -17.5 deg C(1). The flux was found to be proportional to the cube root of the wind speed. At a wind speed of 1 m/s, the volatilization rate was approximately 1.2 and 9 ug/min at -17.5 and 0 deg C, respectively. The calculated volatilization rate at zero wind velocity is 0.8 and 0.07 ug/min at 0 and -20 deg C, respectively(1). For volatilization of droplets, as opposed to a pool, surface affects (droplet spreading), would be important(SRC).
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