Review on the development of defect‐free and ultrathin‐skinned asymmetric membranes for gas separation through manipulation of phase inversion and rheological factors

Abstract

Development of high-performance asymmetric membranes is a major breakthrough in membrane technology. A comprehensive study on original concepts and new advances in membrane formation process is necessary to generate defect-free and ultrathin-skinned asymmetric membranes with superior performance for gas separation process. Correlation of rheological factors with primary-phase inversion process is a novel approach in membrane research that provides a potential platform to improve membrane performance. The former controls general morphology of membrane, whereas the latter further affects molecular orientation in membrane.

High throughput study of phase inversion parameters for polyimide-based SRNF membranes

“…Conditions favoring delayed onset of demixing can reduce or even suppress their formation, e.g. by selecting a non-solvent with limited miscibility with the polymer solution, or by increasing the evaporation time before immersion of the cast film into the coagulation bath [2][3][4][5][6].…”

“…A wide variety of experimental parameters have a large impact on the final morphology of the membranes, and consequently on their performance [1][2][3]. These include the composition of the polymer solution (solvent, cosolvent, additives and their respective concentrations) [7][8][9][10][11], the type of support material (glass, polymer, metal, non-wovens, etc.)…”

The development of high performance P84 co-polyimide hollow fibers for pervaporation dehydration of isopropanol

“…With the significant advance in membrane material research and membrane fabrication in the last two decades, nowadays the phase inversion process is a proven technique to produce defect-free asymmetric membranes through proper control and adjustment of membrane preparation conditions (Chung et al, 1994;Koops et al, 1994;Clausi and Koros, 2000;Ismail and Yean, 2003). Hollow fiber configuration made by this process has been widely used in gas separation, reverse osmosis, ultrafiltration, microfiltration, and other membrane processes due to its large surface to volume ratio, mechanical self-support and high packing density.…”

Effect of coagulant bath on the gas permeation properties of cellulose acetate asymmetric membrane

“…The significant differences of gas permeance among membranes prepared from various solvent-non-solvent pairs could be explained by referring to their morphologies as shown by SEM images (figure 3). Since high value of permeability can be achieved in asymmetric membrane with very thin skin layer [11], it can be concluded that the rest of membranes have less porous substructure that did not allow gas to permeate well. Figure 4 shows selectivity of O 2 /N 2 gas towards CA membrane that prepared with different quench medium.…”