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A comparison of three models for the diffusion of oxygen in electrolyte solutions
Author(s) -
Holtzapple Mark T.,
Eubank Philip T.,
Matthews Michael A.
Publication year - 1989
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260340711
Subject(s) - diffusion , oxygen , aqueous solution , electrolyte , chemistry , thermodynamics , work (physics) , flux (metallurgy) , mole fraction , salt (chemistry) , oxygen transport , electrode , organic chemistry , physics
Diffusion of oxygen through aqueous solutions is of great importance in biological systems. In this work, three models for the diffusion of oxygen through aqueous salt solutions are compared. One model uses mole fraction as the driving force (Fick's Law) and another uses chemical potential. The third model uses the gradient in oxygen activity as the driving force. This new model was chosen because of the availability of oxygen electrodes which directly measure oxygen activity in aqueous solution. These models have been used to reevaluate the technique of measuring O 2 diffusivities. We show that Pick's Law diffusion coefficients do not vary strongly with salt concentration as was erroneously reported in the literature. In addition, we compare the predicted O 2 fluxes of the three models over a wide range in O 2 concentrations. For oxygen concentrations of biological interest, the three models give identical predictions of the flux.