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

Abstract

Low-frequency O 2 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 CO 2 and CH 4 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 CH 4 and CO 2 , respectively, whereas, the CO 2 /CH 4 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. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 124: E199-E204, 2012

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

“…For plasma treated membranes, the selectivity values of the gases tend to be lower; however, the CO 2 /CH 4 selectivity is still higher than 40.41 for O 2 ‐treated plasma as reported in Ref. . In contrast, the permeation of all gases through all membranes increased significantly as shown in Figure .…”

“…The polymer solution was casted on a clear and smooth glass plate to a thickness of about 200 μm. To enhance the gas separation performance of the membranes, preparing conditions were adapted from literatures . These conditions comprised of ET in the normal ambient air for 3 min and an immersion time in a double coagulation bath of deionized water at about 20°C for 15 min, and of MeOH at about 15°C for 2.5 h. After the immersion in the MeOH bath, the membranes were dried in the normal air (about 24–25°C) for 24 h and were dried in an electric oven at 60°C for 3 h before use.…”

“…Lastly, PSF membrane for CO 2 /CH 4 separation was modified by low frequency O 2 ‐plasma. The permeability of plasma treated membrane increased to 5.63 and 68.80 GPU for CH 4 and CO 2 , respectively, whereas, the CO 2 /CH 4 selectivity varied from 7.7–45.3, depending on the treatment conditions …”

“…[1][2][3] Furthermore, the separation and plasticization properties of PSF are in acceptable levels. 3,4 Therefore, many research groups are intensively working on the enhancement of membranes properties and performances; mainly utilizing two types of techniques. 5 The first technique is the modification of the membrane bulk structure by chemical processes.…”

Surface modification of polyamide composite membranes by corona air plasma for gas separation applications

“…Furthermore, some researchers applied the cold plasma methods to directly modify different polymeric membranes for use in the membrane processes such as microltration, ultraltration and membrane distillation. 25) and PSf 26,27 in order to improve their permeation performance for use in the gas separation process. Also, Sadeghi et al 14 applied the corona air plasma to modify the surface of the PES ultraltration membrane to enhance the surface hydrophilicity and permeation properties of the membrane.…”