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

摘要

In the present paper, organic/inorganic membrane has been prepared for gas separation by incorporating heteropolyacids (HPA) such as 12-phosphotungstic acid (PWA) into the base polymer. Flat-sheet membranes were prepared using polyethersulfone (PES) dissolved in N, N-dimethylacetamide (DMAc) with and without the addition of PWA. The membranes were prepared from quaternary (PES/PWA/DMAc/water) and ternary (PES/PWA/DMAc) systems by wet and dry (solvent evaporation) techniques. Composite membranes were produced via a two-stage wet phase inversion method. The skin layer was synthesized from ternary (PVA/PWA/H_2O) system on the surface of PES membrane as the sub layer, using dip coating technique. The permeability and selectivity of H_2, N_2, O_2 and air were tested. In dry method, the porosity of the prepared membrane was slightly increased by addition of PWA. The increased porosity results in flux improvement. By increasing the concentration of PWA in the wet procedure, the channel-like structure appeared. The presence of PWA in the casting solution results in lower flux for O_2 gas and higher selectivity for H_2/O_2 pair.