The transport phenomena of oxygen and nitrogen across a pure polycar bonate
(PC) and CoAlPO4-5/PC membranes were studied. Various CoAlPO4-5 membranes
with different cobalt content were added to polycarbonate membranes to impr
ove the gas transport performance. Oxygen and nitrogen isotherms were studi
ed. Solubility of oxygen and nitrogen was greatly increased by adding CoAlP
O4-5 to the membranes, which also resulted in a higher solubility ratio of
oxygen to nitrogen. It might be that a pinhole of the membrane caused the i
ncrease in diffusivity and a decrease in selectivity when excess CoAlPO4-5
was added. The results also showed that CoAlPO4-5 with a higher cobalt cont
ent would more effectively increase the gas solubility, but make only a min
or change in the solubility ratio of oxygen to nitrogen. It was found that
the increase in oxygen to nitrogen selectivity was mainly due to an increas
ed diffusivity ratio of oxygen to nitrogen when CoAlPO4-5 was added into th
e membranes. (C) 2000 John Wiley & Sons, Inc.