Effect of external factors on the increase in the extraction rate in a vibration treatment on the dynamic interfacial layer

Vibration treatment of a dynamic interfacial layer in the extraction system constituted by an aqueous solution of a salt of a rare-earth element and a solution of di-(2-ethylhexyl)phosphoric acid in heptane (toluene) results in an increase in the process rate. This increase is characterized by an acceleration coefficient defined as the ratio between the lanthanide concentrations in the organic phase after equal intervals of time in systems with and without vibrations. It is shown that the acceleration coefficient depends on the concentration of the extractive agent, initial concentration of an element being extracted, solution pH, and phase contact duration. The observed behavior is explained in terms of the process model suggested by the authors. According to this model, the effect depends on the relative contributions made by a number of interfacial phenomena accompanying the extraction of a lanthanide with solutions of di-(2-ethylhexyl)phosphoric acid in diluents and, in particular, by the spontaneous surface convection and structuring in the interfacial layer.