Solubility and diffusivity of light gases in ethyl cellulose at elevated pressures Effects of ethoxy content

The solubility of He, O2, N2, CH4, and CO2 in ethyl cellulose (EC) membranes with ethoxy contents of 47.2, 47.9, and 49.6% was measured at 35.0°C and at pressures up to ca. 30 atm (3,040 kPa). Mean diffusion coefficients, D̄, for these gases in EC were obtained from the solubility measurements in conjunction with mean permeability coefficients determined in a previous study. The solubility coefficients, S, for the above-mentioned gases in EC increase in the gas order: S(He)⪡S(N2)<S(O2)<S(CH4)<S(CO2); this is also the order of increasing critical temperatures of these gases. The values of D̄ for He, O2, N2, and CH4 at low concentrations in EC increase in the order of decreasing ‘kinetic’ molecular diameters: D̄(CH4)<D̄(N2)