TABLE OF CONTENTS Gas separation by synthetic polymer membranes has long been studied. [233] To obtain a high separation factor for a specific gas, polymer membranes containing specific fixed carriers are used, e.g. cobaltporphyrin for oxygen gas permselectivity [234] and poly[(vinylcyclopentadienyl)manganese for nitrogen gas permselectivity. [235] The permeability coefficient of a gas through the membrane ( P) is the product of the diffusion coefficient ( D) of a gas through the membrane and the solubility constant ( S) of the gas in the membrane: P = D S. The separation factor ( ? ij) of two gases can be expressed as the ratio of the pure component permeability coefficient of the gas pair: ? ij = ( P i/ P j) = ( D i S i/ D j S j).
Acidic gas has been removed from mixed gas by using an ion exchange membrane ion exchanged with a suitable carrier. Namely, when the carrier is ion exchanged with ion exchange groups of the membrane and one surface of the membrane contacts the mixed gas, the carrier forms a complex with a specific gas, migrates through the membrane and releases the gas at the opposite side of the membrane. This means there is an increase in the solubility constant ( S) of the specific gas in the membrane. When amines such as ethylenediamine are ion exchanged with sulfonic acid groups of a...
