Asymmetric polysulfone gas separation membranes treated by low pressure DC glow discharge plasmas

摘要

Asymmetric polysulfone (PSF) gas separation membranes were prepared at different conditions such as non-solvent concentration, evaporation time (ET) and coagulation bath temperature (CBT). In addition, effects of low-pressure DC glow discharge plasma on the characteristics of PSF membranes were investigated. PSF membranes both before and after plasma treatment were characterized by several techniques, including contact angle measurement, scanning electron microscope (SEM), dynamic mechanical thermal analysis (DMTA), and atomic force microscopy (AFM). Furthermore, the performance of membranes was evaluated in terms of permeability of CO2, CH4, O-2,O- and N-2 gases. The ideal selectivity of CO2/CH4 and O-2/N-2 and surface free energy was calculated. Results showed that the EtOH concentration, ET and CBT affect the morphology of PSF membranes. For membranes prepared from a casting solution consisting of PSF 26.0, NMP 28.0, THF 28.0, and EtOH 18.0 wt % and ET for 3 min, the maximum selectivity of untreated membrane is about 69.76 and 12.59 for CO2/CH4 and O-2/N-2, respectively. After plasma treatment, the ideal selectivity is receded; however, the CO2/CH4 is still higher than 40.41 at pressure of 5 bars. Finally, preparation conditions and DC glow discharge plasmas have significant effects on the characteristics of the PSF membranes and result in an increase of the gas permeation. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42116.