In this study,a generalized expression for gas permeance is developed for both liquid membranes and fixed carrier membranes.The expression is convenient and practical to demonstrate the relationship between the permeance and the partial pressure of the targeted gas.The generalized expression was used to calculate the facilitated transport parameters of a liquid membrane and a fixed carrier membrane,including diffusion coefficient of uncomplexed solute and solute-carrier complex as well as reaction equilibrium constant,by fitting the experimental data of the permeance varying with the partial feed pressure.The calculated parameters were agreed well with those in the literature.To check the proposed expression,the gas permeances of three different facilitated transport membranes were predicted.The predicted results were found to be in satisfactory agreement with the experimental results.Besides,with this model,the prediction for the effects of membrane thickness,carrier concentrat