I'm working on absorption of SO2 and NO2 with chemical reaction in NaOH solution. To make it easier, the reaction with NO2 does not exist, and only the reaction SO2+NaOH-> proceed irreversibly and with infinite speed. The mass transfer on the side of gas is easily estimated, however, on the side of liquid it could be troublesome. Two mass transfer fluxes are required, thus two diffusivities are needed:
1) Diffusivity of SO2 (Na2SO3 because of conditions assumed) in the mixture
2) Diffusivity of NO2 in the mixture
The literature tells me that it's hard to predict overall diffusivity (properties of gases and liquids) and suggest the ways of thinking by:
- Kooijmann and Taylor
- Keit and Anderson
- Bandrowski and Kubaczka
The first pair predict the solution of binary diffusivities of all components referring to the self-diffusivities of each, not giving the diffusivity of the solution at all. The two last articles are not available for me. In general, articles refer to a multicomponent SM equation where diffusivities are binary in matrix form, whereas I need to estimate diffusivity in the mixture (treating the mixture as one component). Does anyone have a solution to such a problem? Has anyone of you estimated the diffusivity of such a complex mixture?
This is a difficult problem due to the reactions involved. It is a multi-component system, so unless the gas concentrations are very low, it does need to be treated as such. The flow or diffusion of any one component sets up flows or diffusion of the other components: hence the need for a diffusion matrix to fully describe the system. For a three component system this is 2 x 2.
A good book is E. L. Cussler, Diffusion, CUP, 2009. A paper relevant to your problem is Leaist, D. G. Journal of Physical Chemistry (1983), 87(24), 4936-9, Gas absorption with instantaneous chemical reaction. Absorption of sulfur dioxide by aqueous sodium bisulfite
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