Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Liquid-liquid equilibrium data for butyric acid (BA) extraction by phosphonium decanoate ionic liquid (IL) were measured and modelled. Extended more general extraction mechanism taking into account differences in IL anion basicities was suggested. The overall extraction mechanism involving three sub-mechanisms of competitive and non-competitive extraction of BA and water co-extraction, were successfully applied to the system with phosphonium decanoate. Formation of (p, 1) complexes with p up to 16 molecules of BA with one ion pair of IL, was supposed. Three times lower value of stability constant of the first ILBA bond in decanoate compared to phosphinate ILs could result in easier regeneration of acid loaded IL in vacuum distillation. Aggregation and micellar structures in water saturated IL were confirmed by DLS measurements. Concentration dependence of equilibrium solvent phase viscosities goes through a maximum which corresponds with a minimum in the dependences of density and water content due to changes in solvent phase composition. The tested IL can be an effective extractant for the separation of organic acids from production media of the fermentation process.