Pillared cloisite 15A as an enhancement filler in polysulfone mixed matrix membranes for CO2/N2 and O2/N2 gas separation

Abstract

The Cloisite 15A (C‒15A), an organically modified montmorillonite clay, was further modified with iron (Fe) pillars. Mixed matrix membranes (MMMs) were fabricated by incorporating Fe pillared Cloisite 15A (P–C15A) at different loading percentage of 0.1–1.5 wt% within the polysulfone (PSf) matrix. Fabricated membranes were characterized using thermal studies (TGA and DSC) and scanning electron microscopy (SEM). The morphological studies of fabricated MMMs confirmed that the P–C15A was well embedded through the PSf matrix. To investigate the effect of P–C15A incorporation, MMMs were tested for their gas permeation behavior using pure CO2, N2, and O2 gases. The gas permeation of MMMs was increased with the increase in loading percentage of P–C15A, whereas the gas selectivity was maintained at par to that of neat PSf membrane until it diminished at 1.5 wt% percentage of P–C15A causing mineral agglomeration. PSf/P–C15A (1 wt%) MMMs exhibited 232% and 274% increase in CO2 and O2 gas permeability respectively, while showing minimal variation in the selectivity of O2/N2 and CO2/N2 compared to that of neat PSf membrane. Furthermore, the gas separation performance of neat and P–C15A incorporated MMMs were compared with the Robeson upper bound. The PSf/P–C15A (1 wt%) MMM shown to have CO2 permeability of 18.01 barrer with the CO2/N2 and O2/N2 gas pair selectivities of 4.95 and 18.34 respectively, which depicted closeness towards the Robeson upper bound.