Investigation of performance of Pebax/ Poly(vinyl alcohol) blend membrane for carbon dioxide separation from nitrogen

Research subject: 

Selectivity and permeability are the major parameters of polymeric membranes in gas separation process. Hence, nowadays in order to improve aforementioned parameters, modification and enhancement issues for such membrane have been highly noticed.

Research approach: 

In this study, in order to improve the performance of polymeric membranes, the two-component blend membranes containing Pebax®1657 and PVA were synthesized for CO2 separation. The effect of different PVA concentrations within the Pebax matrix on structure, morphology and gas separation properties of resultant membranes was investigated. The chemical bonds, crystallinity and cross-sectional morphology studied through, Fourier transform infrared (FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), and were utilized.

The results of the thermal analysis indicated an increase in crystallinity and also glass transition temperature in presence of 5 – 15 wt.% PVA, while the membrane crystallinity decreased by increasing the PVA content up to 20 wt.%. FESEM images demonstrated a uniform cross-section without any cracks and defects for neat Pebax membrane but by adding PVA to Pebax matrix, appeared cracks and cave structures on the cross- section of blend membranes. The CO2/CH4 separation performance of membranes was measured using a constant volume set up at 30°C and feed pressure of 2, 6 and 10 bar. The obtained results revealed that the CO2 permeability in blend membranes improved as the PVA content increased within the membrane. The best obtained CO2 permeability was 204.64 Barrer which gained by Pebax/PVA (20wt.%) at feed pressure of 10 bar. Moreover, the highest selectivity of CO2/N2 for blend membrane with 15 wt.% of PVA was about 100.21 at 10 bar and 30°C.