Structure and transport properties of cation exchange gel membranes: facilitated transport of ethene with silver ions as carriers

The transition time t(a) of the rate of transport of gaseous ethene to reach a stationary value across two types of cation exchange gel membranes shows a characteristic dependence on the mole fraction (x) over tilde(Ag+) of silver counter ions present in the gel phase. Silver ions are carriers for ethene. The corresponding dependence of the characteristic time of adsorption t(0.9) of ethene by the same gels shows similar features. Both curves exhibit a maximum at about the same (small) value of (x) over tilde(Ag+). The adsorption kinetics is studied using a gravimetric method. It is concluded that these phenomena reflect structural inhomogeneities of the gel matrix which have been detected in independent small-angle and ultra small-angle X-ray scattering (SAXS and USAXS) experiments. (C) 2000 Elsevier Science B.V. All rights reserved.