Measurements of Saturated Solubility and Diffusion Coefficient of Pure Gases to a Mineral Oil.

Abstract

The present paper deals with precise measurements of the diffusion coefficients as well as the saturated solubilities of single component gases such as N2, O2 and CO2 to a mineral oil. The method to determine the diffusivity is based on measuring the pressure changes caused by the one-dimensional diffusion between the gas and the oil enclosed in an airtight container. For N2 and O2 the profiles of the measured pressure changes agree well with those predicted by the diffusion theory, whereas that is not the case with CO2. Although the reason why CO2 does not seem to obey the diffusion theory has yet to be studied, it may suggest the possibility that the diffusion coefficient varies with the pressure, considering that the range of pressure changes in the diffusivity measurement was much larger for CO2 than for the other two gases. The scattering of the diffusion coefficients obtained for N2 and O2 by this method fell to within +30% of the average. Moreover the solubility measurements have revealed that Henry's law holds true between the three pure gases and the oil tested, and that O2 and CO2 dissolve into the oil approximately two and ten times more, respectively, than N2.