High performance compatible thiazole-based polymeric blend cellulose acetate membrane as selective CO₂ absorbent and molecular sieve

Green blend membranes comprise of high thermal resistance ortho-linked thiazole-based polyimine (PM-4) including thioether linkage were fabricated in combination of glassy cellulose acetate (CA). The thermal stabilities of PMs were examined using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Morphological aspects and functional groups of the membranes were investigated via field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy–attenuated total reflectance (FTIR-ATR) analysis respectively. X-ray diffraction (XRD) and mechanical strength were determined as well. The effects of polyimine content, pressure and temperature were studied on CO₂ permeability (P) and selectivity. The pressure changes revealed exponentially increases on CO₂ permeability by plasticization, facilitated transfer and solution-diffusion mechanisms, but decreases on CH₄ and N₂ permeations. Remarkable permeation (P = 3000 Barrer) of CA/PM-4 (1:3 % w/w) and ideal selectivity ratios of CO₂/N₂ = 59, CO₂/CH₄ = 33.7 were obtained at 3 bar and 35 °C versus neat CA membrane.