INFLUENCE OF ELECTROLYTES ON LIQUID-LIQUID-EXTRACTION

The strong influence of electrolytes on the partition behavior of char ged species is demonstrated in aqueous and aqueous-organic two-phase s ystems used for extraction. The effects are modeled with an extended A lbertsson model which takes into account the electrostatic potential d ifference between coexisting phases. The partition coefficient of a sp ecies regarded may change by a factor of 50 by the addititon of differ ent salts. The electrostatic potential close to the interface is then described by direct integration of the Poisson equation. The results a gree with those for the Galvani potential between the bulk phases obta ined from the Albertsson model. The influence of ionic species includi ng surfactants on the mass transfer in extraction is discussed. Finall y, the coalescence of Liquid dispersions is investigated with electrol ytes present in the system. The settling times can be varied by a fact or of 1000 in some systems, if appropriate salts ave added at concentr ations around 1 mol/m(3). The experimental results are again interpret ed on a microscopic level on the basis of the diffusive double layers at the interface.