Reactive liquid-liquid extraction in segmented flows in microsystems

The intensification of liquid-liquid extraction systems has been studied for the screening of new extractants and the optimization of the parameters governing extraction processes (temperature, pH, and concentrations). The aim of this PhD is to understand and develop a model of mass transfer associated to reactive liquid-liquid extraction processes in segmented flow microsystems. Thanks to micro-fluidic properties, the consumption of reactants is reduced, the specific interfacial area is monitorable, and the diffusive resistance to mass transfer can be minimized. The hydrodynamics of segmented flows were first studied and allowed the determination of reference cartographies for T and cross junctions for two liquid-liquid extraction chemical systems, Eu(III) in [HNO₃] = 4 mol.L^-1/N,N'-dimethyl-N,N'-dibutyl-2-tetradecyl-malonamide (DMDBTDMA) and U(VI) in [HCl]= 5 mol.L^-1/tri-n-octylmethylammonium chloride (Aliquat 336), leading to the proposal and validation of a predictive model in the dripping regime, hence allowing the determination and maximization of the specific interfacial area. Consequently, the study of mass transfer for the Eu(III)/DMDBTDMA system in T junctions lead to the definition of both a new analytical and numerical model for segmented flow in microsystems ensuring a proper description of interfacial kinetics. The numerical model was applied to the implementation of an innovative process for the determination of the liquid-liquid extraction reaction coefficient kf in segmented flow microsystems in both chemical and diffusional regime, on one side, and to the implementation of a process for micro-chip prototyping on the other side. (author)