Unsteady-State Interphase Diffusion
Prepared by H. Binous
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This Demonstration considers the mass transfer of a substance A between two immiscible solvents I and II. The concentration in both phases is plotted versus position for various values of the diffusion coefficients (in  and , time (in seconds), and Henry law constant  (a dimensionless constant). When  the concentration of A is continuous at the interface, which is not typical. The concentration profiles are solutions of the following diffusion equations and boundary conditions:

,

,

 for ,

 for ,

at ,

at ,

at .

Using Laplace transforms, one can easily derive analytical expressions of the concentrations in phases I and II:

,

.