Abstract:
In the present work we prepare blend membranes by incorporating the ionic liquid (3-(trimethoxysilyl) propan-1-aminium acetate ([APTMS][Ac])) as filler into polymers of intrinsic micro porosity PIM-1. The FTIR Spectroscopy and Scanning electron Microscopy (SEM) analysis indicated uniform dispersion and good polymer filler compatibility even with increase in loading i-e from 0 wt. % IL to 10 wt. % IL. The gas transport properties were investigated with filler loading of upto 10 wt. % of IL and results indicated that the blend membrane reduced permeability slightly but improved the selectivity. CO2 gas permeability of the pristine PIM-1 membrane was 4387 Barrer, which dropped to 2754 Barrer (37.22 % decrease) at 10% filler loading for the blend membrane. The ideal selectivity enhanced from 19.58 to 28.99 for CO2/CH4 and 20.89 to 31.66 for CO2/N2 by increasing the [APTMS] [Ac] content (0wt. % - 10wt. %). Binary gas mixtures gas separation measurements demonstrated same trend as obtained from single gas permeability measurements. For CO2/CH4 gas mixture, incorporation of IL in polymer matrix increased the selectivity by 58.62% and decreased permeability of CO2 by 40.44% as compared to the pristine PIM-1 membrane. For CO2/N2 gas mixture, incorporation of IL in polymer matrix increased the selectivity by 40.11% and decreased the permeability of CO2 by 39.07% as compared to pristine PIM-1 membrane. The permeability decrease can be credited to the filling of free volume voids in the PIM-1 polymer matrix by the IL [APTMS][Ac] whereas selectivity increase is due to the strong interaction and high solubility of CO2 in the ionic liquid. The solubility coefficient of CO2 increased with increasing concentration of ionic liquid therefore indicating high solubility of IL in polymer matrix. Hence studied PIM-1/[APTMS][Ac] blend membranes can be used ideally as selective layer intended for gas separation.
