Polymeric and mixed matrix membranes for gas separation

This study deals with Polyethersulfone (representative glassy polymer) and PEBAX-1657 (representative rubbery polymer) membranes for gas separation. Fundamental understanding of transport behavior of pure (CO2, O2 and N2) and binary gas (CO2/N2 and O2/N2) mixtures are performed through systematic pressure and composition study. Modelling studies are conducted to bridge the gap between pure and mixed gas permeation mechanism in the context of condensable (e.g., CO2) and non-condensable (O2 and N2) gases. For glassy polymer, dual mode sorption and partial immobilization theory is used to understand mechanism through competitive and non-competitive models. Whereas, for rubbery polymer, Flory-Huggins estimations are used to understand the relative contributions of solubility and diffusivity values for the observed permeability. Further, effect of ZIF-8 (Zeolitic Imidazolate Framework) filler is studied in the glassy and rubbery membrane with pure and mixed gas studies to enhance gas permeation properties of membranes, which are called Mixed Matrix Membranes. MMM studies are performed for the compositions of CO2/N2 (11/89 vol%) and O2/N2 (21/79 vol%) membranes, which are representing the compositions of flue gas and air. Pycnometry and SEM studies are carried out for quantitative identification of different phases (polymer, filler and void) present in the MMM. Dispersed (e.g. Maxwell) and resistance modelling (e.g. Henis and Tripodi) studies are carried out for estimating permeability of gases in MMM with the aid of quantitative phase estimations.