Figure 5. (a) Gas permeation properties and CO2/CH4 selectivities of the (I) pristine PSF membrane, (II) MOF-NP/PSF, (III) pMOF-MS/PSF, and (IV) pUiO-66-MS/PSF MMMs. (b) CO2 and CH4adsorption isotherms with the corresponding fitting lines by dual sorption model. (c) Solubility and CO2/CH4 solubility selectivity of different membranes. (d) Diffusivity and CO2/CH4 diffusivity selectivity of different membranes.