Quantitative estimation of the capacity, selectivity, and phase miscibility in real extraction systems with two solvents

In the development of a number of technological processes based on two-solvent extraction of mixtures of coal-tar origin, such as isomers of phenols and bases, naphthalene and thionaphthene, etc., interphase mass transfer was investigated in real extraction systems including concentrated solutions and technical multicomponent mixtures as solvents and mixtures to be separated. The results of these investigations are correlated in this paper in order to examine the possibility of describing interphase mass transfer in relation to the composition of the extraction system. Comparison of the results of investigations of different types of mass transfer in a number of real extraction systems demonstrated the possibility of quantitative assessment of the selectivity, extractant capacity, and phase miscibility in relation to the composition of the system within the optimal ranges of variation of the factors characterizing that composition. The capacity and phase miscibility are determined by the character of the interaction and depend on all the factors characterizing the composition of the extraction mixture, while the selectivity depends only on the composition of the mixture to be separated.