Solute distribution between phases at equilibrium some examples

7 Solute distribution between phases at equilibrium some examples 

When two or more immiscible phases are at equilibrium, species generally distribute themselves between the phases such that the uniform and constant concentration of a species in one phase is different from those in other phases. Since there can be a large number of combinations of two-phase systems in equilibrium (see Table 3.3.1), the variety in distribution coefficient (k, ) relations is enormous. Our objective here is somewhat limited. We pick a few common two-phase systems in equilibrium and illustrate the relations between the concentrations of any solute between the phases at equilibrium. This will not only allow us to develop integrated flux expressions in multiphase 

From standard thermodynamics texts, the fugacity of species i in each phase may be expressed as 

If the gas phase behaves as an ideal gas and the liquid phase behaves as an ideal solution, we know that ig S 1, yu= and Pig — XigP. If the gas phase is distinctly in the nonvapor region (see item (5), Table 3.3.2), it is known from thermodynamics that 

If the gaseous phase can he considered as a vapor, then the distribution of a species between the vapor and liquid phase is of interest. Obviously, the species can be a major constituent of each phase here. The equilibrium ratio /C, of a component i is defined as (equation (1.4.1)) 

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