พรทิพย์ เหลืองรุจิวงศ์. Investigation of Carrier Saturation Phenomenon in Facilitated Transport Membranes. Master's Degree(Chemical Engineering). King Mongkut's University of Technology Thonburi. : King Mongkut's University of Technology Thonburi, 2005.
Investigation of Carrier Saturation Phenomenon in Facilitated Transport Membranes
Abstract:
This research was performed to investigate carrier saturation phenomenon in facilitated transport membranes
by determining the permeation fluxes of unsaturated hydrocarbons through the membranes containing Ag+-ion as a carrier. The
effects of carrier loading and complex stability were studied from the permeation experiments of four liquid olefins through
Nafion?117 membranes containing either Na+-ion or various amount of Ag+-ion. Single-component facilitated transports of
ethylbenzene, styrene, cyclohexene and 1-hexene were carried out using the feed concentrations ranging from 0.5 M to pure.
Equilibrium constants of the Ag+-solute complex formation, determined by distribution method, were 0.7, 2.2, 32.0, 129.1 M-1,
respectively. Carrier saturation was not found with the membrane incorporated with 2.67 M Ag+-ion. As the carrier concentration
was reduced to 0.51 M, increase in the feed concentration beyond 4.5 M had very little effect on ethylbenzene flux, suggesting the
onset of carrier saturation. Styrene and cyclohexene underwent the carrier saturation when the carrier loading was 0.25 M, while
a complete saturation was not observed with 1-hexene. Extraction of solute from the membranes revealed that less than 50 percent
of Ag+-ions were occupied when the carrier saturation occurred. It was also found that the ability of solute to use available Ag+-ions
in the membrane was dependent on the equilibrium constant. In addition, the effect of carrier mobility on carrier saturation was observed
from measurement of ethylene fluxes through the poly(vinyl alcohol)-based membranes in mobile-carrier and fixed-carrier form. For the
membranes containing 0.49 M Ag+-ion, the fluxes obtained from the mobile-carrier membrane were higher than those obtained from the
fixed-carrier membrane. It was also found that the fixed-carrier membrane was more susceptible to the carrier saturation than the mobile-
carrier membrane. However, the effect of carrier mobility on permeation flux and carrier saturation was not noticed as the carrier concent
ration was increased. Finally, the mathematical model proposed by Al-Marzouqi was applied to demonstrate the effects of carrier mobility
on permeation flux and carrier saturation. The results from the model were in agreement with the experimental results.