Title of article :
The role of permeant molar volume in the solution-diffusion model transport equations
Author/Authors :
J.G. Wijmans، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2004
Pages :
12
From page :
39
To page :
50
Abstract :
The solution-diffusion model is the most widely used model of permeation in non-porous polymer membranes. The model allows the membrane separation processes of dialysis, reverse osmosis, gas separation and pervaporation to be described by a series of simple interrelated equations. To obtain these simple equations, a number of approximations and assumptions are made. One implicit assumption is that the molar volume of each permeant in the membrane phase is equal to the molar volume of the permeant in the liquid phases in contact with the membrane. Literature data, however, indicate that this assumption is not always valid. In this paper, the transport equations are derived for the case when the permeant molar volume in the membrane phase and the liquid phase are not equal. The difference between the complete equations and the usual approximate equations is called the molar volume correction factor. This factor is absent in the gas transport equation and is insignificant in dialysis and pervaporation applications. The correction factor can be significant, however, in high-pressure reverse osmosis processes. This is particularly true when relatively large molecules are present, for example, in the removal of solvent from solvent/oil mixtures. In such cases, the molar volume correction factor can significantly affect the dependence of the reverse osmosis flux on pressure.
Keywords :
Pervaporation , Gas separation , Solution-diffusion , Reverse osmosis , Dialysis
Journal title :
Journal of Membrane Science
Serial Year :
2004
Journal title :
Journal of Membrane Science
Record number :
1351381
Link To Document :
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