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Appendix

Simple methodi for determination of the diffusivity

in gas and liquid phase

In diffusion of gas A in gas B, or the opposite of gas B in gas A, the
value of diffusivity DG can be determined using the equation

0.00155T s/3
D
a= ]
M A M B

where T is the absolute temperature in K;
P- the pressure in bar;
M A and Mg- mol mass of the components A and B;
VA and Vg - mol volume of the components A and B, determined as a sum of the
atom volumes of the elements in the gas molecules. The values of VA for some
atoms and molecules are presented in Table 1 A, [40].
In case of more complex compounds for calculating the mol volume,
the respective structure constants, given below, must be added to the sum of the
atom volumes.

Structure Structure constants
Benzene ring 15
Naphthalene 30
Anthracene 47.5

From Eq. (1A) is easy to see, that if the diffusivity for a given system
Dai is known to a temperature T t at a pressure Pi, the diffusivity D G2 for the
same system at temperature T 3 and pressure J°j can be calculated by the
equation.

(2A)