AbstractPermeation behavior of pure CO2, O2, and N2and separation characteristics of CO2–air mixtures were examined using hollow fiber modules of asymmetric cellulose triacetate membrane at 30°C. The ideal separation factor for CO2relative to N2ranged from 21 to 24. Permeation behavior for pure CO2was interpreted in terms of the total immobilization model, i.e., a limiting case of the dual‐mode mobility model for glassy polymer, where the diffusion coefficient for Henry's law mode is not assumed to be constant and depends on gas pressure via a modified free‐volume model. Based on pure gas permeabilities to CO2, O2, and N2, simulation for the separation of CO2–air mixtures was made using a counter‐current plug flow model, and the result fitted the corresponding experimental data fairly well. Membrane plasticization induced by CO2had negligible effect on permeation to mixture of CO2and air in the range of CO2composition up to 50 and upstream total pressure up
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