1989 Volume 15 Issue 6 Pages 1057-1063
To develop a method for the selection of a diluent that increases DA, the distribution ratio for extraction of organic acid with amine, diluent effects on the extraction of acetic acid with tri-n-octylamine (TOA) were investigated. The experimental data show that DA depends on the kind of diluent and the mixing ratio of TOA to diluent.
A model composed of both dominant association and physical distribution is proposed to describe the extraction equilibrium. The equilibrium constants of the association involved in the model can be estimated on the basis of the excess volume with respect to the pseudo-binary mixture of TOA and acetic acid. The DA's predicted by the model are consistent with the experimental data. It is found that diluents of strong acceptors decrease the associating order of acetic acid with TOA, and make DA high in the region of low CA, aq. Finally, this paper proposes an approach to the selection of diluent based on these results.
