A new ternary Pebax®1657/maltitol/ZIF-8 mixed matrix membrane for efficient CO2 separation

In this study, a novel high-performance mixed matrix membrane (MMM) based on poly(ether-b-amide) was fabricated in which the synthesized ZIF-8 nanoparticles embedded into a maltitol-modified Pebax®1657. Maltitol (as an inexpensive low molecular weight additive) provides a good CO2 affinity. Moreover, an existence of selective affinity in ZIF-8 nanoparticles toward CO2, enhances the CO2 permeability and its selectivity over other penetrants. The synthesized ZIF-8 nanoparticles were added (0–10 wt%) into the Pebax/maltitol (20 wt%) matrix to prepare the Pebax/maltitol/ZIF-8 MMMs. Field Emission Scanning electron microscopy (FESEM) was applied to evaluate the MMM morphology, where excellent dispersion was shown. Thermogravimetric analysis (TGA) was used to determine the thermal properties of prepared membranes. The TGA results indicated that the decomposition temperature of membranes raised as the ZIF-8 loading increased within the Pebax matrix. Differential scanning calorimetry (DSC) implied the disruptive role of MOF on polymer chain mobility which reduces the overall crystallinity and increases the glass transition temperature of MMMs. The analysis of gas permeability at 30 °C and 10 bar revealed that Pebax/maltitol (20 wt%)/ZIF-8 (10 wt%) membrane showed the highest CO2 permeability of 429.57 Barrer. In addition, the highest selectivity values of 69.31 and 26.59 for CO2/N2 and CO2/CH4 separation, respectively; obtained by Pebax/maltitol (20 wt%)/ZIF-8 (5 wt%) at 30 °C and 10 bar. Finally, the performance of Pebax/maltitol (20 wt%)/ZIF-8 (5 wt%) membrane was able to surpass the Robeson upper bound for the CO2/N2 separation and Robeson prior bound for CO2/CH4 one.