Liquid liquid extraction under electrical field: external electrode contactor

This document presents two versions of the same thesis. After presenting their operating mechanisms and the areas to which they apply, the liquid-liquid extraction columns under an electric field are classified into three categories. The criticism of these devices led to design a contactor equipped with electrodes insulated from fluids by a dielectric coating and powered by an adjustable high-voltage frequency generator. Hydrodynamic study: - the scattered-phase retention measurement allows the analysis of the contactor functioning, which reaches the electrostatic dispersal regime at 4 kilovolts per centimeter. The following points are shown: Electrode coating introduces a narrowing of the field, increasing with the conductivity of the continuous phase and the variable phase with frequency. The electrostatic Weber number is the similarity invariant, determining the required field to disperse the di-phasic medium. Frequency does not affect retention. - the of phase flow is characterized by analyzing the distribution of stay times, thanks to a technique of tracing by a dye soluble technique in the continuous organic phase: the electrostatic dispersion ensures the minimization of the phenomenon of re-mixing. Electrical behavior: the contactor is equivalent to a capacity, the value of which reflects the level of retention in the dispersed phase. Transfer of matter: - for an isolated drop to which a periodic solicitation is applied by means of a pulse field, the gain is significant only to the small diameters; it does not appear very much at the contactor level. In an electrostatic dispersal regime, the contactor reaches very reduced stage times. Frequency has a notable influence, with the number of transfer units doubling between 50 and 800 Hertz. Global efficiency is linked to the exchange area as well as to the rapidity of break-coalescence cycles. (author)