Selection of Selective Solvents

The selectivities, at infinite dilution are usually used for the selection of selective solvents. These values can be calculated from activity coefficients at infinite dilution (extractive distillation, extraction) or from Henry coefficients (absorption). 

The required activity coefficients can either be calculated (predicted) with the help of thermodynamic models (group contribution methods) or obtained from factual data banks. The procedure for the selection of selective solvents for extractive distillation processes is given in refs. 4 and 5. The capacity C, of extractants can be estimated using activity coefficients at infinite dilution. 

For absorption processes, the partition coefficients and the separation factors at infinite dilution can be calculated directly using Henry coefficients. 

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