Effect of low‐frequency oxygen plasma on polysulfone membranes for CO2/CH4 Separation

Abstract

AbstractLow‐frequency O2 plasma was used to modify the surface of polysulfone gas‐separation membranes. The effects of the treatment time and plasma power input on the membranes were also investigated. Pure CO2 and CH4 gas‐permeation measurements were performed before and after plasma treatment. The results show the increase of permeability of the treated membranes due to surface ablation and surface polarization up to 5.63 and 68.80 gas‐permeation units for CH4 and CO2, respectively, whereas, the CO2/CH4 selectivity of the treated membranes varied from 7.7 to 45.3, depending on the treatment conditions. Attenuated total reflection–Fourier transform infrared spectroscopy determined the introduction of oxygen‐containing polar groups on the surface of the membranes following treatment. Water contact angle measurements also showed a significant increase in the wettability of the membranes after plasma treatment. Furthermore, the morphology of the surface of the membranes was studied by scanning electron microscopy. The images displayed a gradual smoothness of the surface under mild treatment conditions. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012