Effect of dodeca-tungstophosphric acid on morphology and performance of polyethersulfone membrane for gas separation

In the present paper, organic/inorganic membrane has been prepared for gas separation by incorporating 12-phosphotungstic acid (PWA) into the base polymer. Flat-sheet composite membranes were produced via phase inversion method. The PVA/PWA skin layer was synthesized on the PES/PWA membranes as a sub layer, using dip-coating technique. The sub layers were prepared from quaternary (PES/PWA/DMAc/water) and ternary (PES/PWA/DMAc) systems by wet and dry techniques. The permeability and selectivity of H2, N2, O2 and air were tested. The morphology of the prepared membranes was investigated by scanning electron microscopy (SEM). The presence of PWA in the top and sub layers (2 wt.% to 6 wt.%) causes a great increase for the selectivity of H2/O2 pair. This is related to decrease flux for O2 and increase flux for H2. The presence of PWA particles in the network of PES membrane allows higher permeation of N2 compared to O2 molecules. The percentage of O2 in the air is about 79%, this leads to that the flux of air is higher than O2 and it is lower than N2 gas. The performance of prepared composite membranes (sub layer prepared by dry procedure) with higher PWA concentration demonstrated better performance compared to the other compositions.

Keywords:

morphology , gas separation , polyethersulfone , polyvinylalcohol , polytungstophosphric acid