Synthetic membranes, based on polymers or inorganic membranes, are now used in a wide variety of gas separations. For gas separation membranes, during the 1980’s, permeability data on six common gases were complied, and the tradeoff relationship was analyzed. The upper bound relationship was established empirically. Recognizing the exquisite permeability and selectivity of biological membranes and the deleterious nature of broad pore size distributions and flexibility of polymer chains on permeability/selectivity combinations, a number of approaches have been pursued to develop membranes with better transport and separation properties. There has been an evolution in design of materials for both gas and liquid separation membranes, brought about by advances in structural control of materials and by better understanding of natural membranes.

• 박호범(한양대학교 에너지공학과, Hanyang University, Department of Energy Engineering) | Ho Bum Park