Liquid-liquid extraction is a complex chemical purification process, which is associated with many thermodynamic and kinetic values. This makes its application in the recycling industry difficult, as it deals with waste streams that have highly variable compositions. In this regard, modelling an extraction process using microfluidics proves to be a useful approach to allow rapid adaptation to such composition changes, if development can be shown to be more accurate, faster, and safer than the classical batch approach with separate analysis. Here, the first automated microfluidic tool integrated with online X-ray fluorescence (XRF) is reported to study liquid-liquid extraction processes by enabling metal concentration quantification. The measurement is automated and performed for both aqueous and organic phases to improve accuracy.Overall, this fully automated approach shows that: (i) Thermodynamic and kinetic values associated with these processes can rapidly and efficiently be obtained simultaneously (in less than 13 hours with a resulting liquid use of less than 20 mL). (ii) Numerical simulations are consistent with the experimental data and provide rare insights regarding the respective contributions to the overall kinetic of the extraction system.

Liquid-liquid extraction processes, characterized on-line by instrumented microfluidic platform, significantly enhance the development of predictive thermodynamic models, such as ienaics, and lay the foundations for new approaches to improve kinetic models which combine transport and chemistry. Instrumented microfluidics enables precise measurement of free energy of transfer of species at equilibria and their associated characteristic transfer times, faster and more accurately than its batch mode counterpart. Computer controlled and fully automatized, our platform illustrated the kinetic differences of high extraction's of Ytterbium (Yb) and Iron (Fe), two elements reported as having very different extraction efficiencies due to different molecular forces competing with complexation when modifiers are used together with extractants. Once collected and processed, the kinetics show two distinct behaviors of these two metallic elements: depending on the temperature, Fe could display a very slow extraction profile when compared to Yb.

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