University of Surrey

Test tubes in the lab Research in the ATI Dance Research

The interferometric study of liquid transport across membranes.

Bansal, A. (1988) The interferometric study of liquid transport across membranes. Doctoral thesis, University of Surrey (United Kingdom)..

[img]
Preview
Text
10797615.pdf
Available under License Creative Commons Attribution Non-commercial Share Alike.

Download (7MB) | Preview

Abstract

A Twyman-Green interferometer was used to study the selective transport of ethanol-water mixtures of various concentration across a nonporous homogeneous silicone rubber membrane at 25°C. The instrument developed enabled the measurement of the transient concentration profiles within the boundary layers bathing the membrane. Measurements as close as 5um from the membrane surface were possible. The majority of the reported interferometric studies of liquid/membrane transport have been limited to the observation of the fringes and stop short of a full theoretical analysis. Such analysis is complicated by the optical effects of light deflection and the computational burden involved in the transient solution of the mathematical models required to describe membrane transport. A rigorous treatment of light deflection was developed on the basis of Fermat's principle of least time. The transient numerical solution of the model equations was accomplished by the application of the method of lines. To decouple the equilibrium and kinetic phenomena in membrane transport requires the independent measurement of the sorption isotherm. Traditional techniques for measuring the extent and composition of the imbibed phase involve removing the membrane from the liquid and are therefore limited by the inherent difficulties of obtaining a 'clean' separation. This was circumvented by measuring the excess (relative) sorption isotherm without removing the membrane from the liquid. The data was analysed in terms of Flory-Huggins thermodynamics which was fitted to the measured excess isotherm across the entire concentration range. For a binary mixture, transport across a homogeneous membrane involves two simultaneous fluxes which can be coupled through kinetic and/or equilibrium interactions. A measure of the extent of coupling was obtained by comparing the results from a simplified 'decoupled' flux model with those based on a 'coupled' flux model allowing for equilibrium interactions. Such interactions were found to have little effect on the flux of ethanol but strongly influenced the flux of water across silicone rubber. In particular, coupling through equilibrium interaction was found to be responsible for as much as 75% of the total flux of water. The diffusion coefficients of both ethanol and water in silicone rubber were shown to decrease strongly with alcohol concentration.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
NameEmailORCID
Bansal, A.
Date : 1988
Contributors :
ContributionNameEmailORCID
http://www.loc.gov/loc.terms/relators/THS
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 1988.
Depositing User : EPrints Services
Date Deposited : 22 Jun 2018 09:50
Last Modified : 06 Nov 2018 16:52
URI: http://epubs.surrey.ac.uk/id/eprint/847237

Actions (login required)

View Item View Item

Downloads

Downloads per month over past year


Information about this web site

© The University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom.
+44 (0)1483 300800