Extraction liquide-liquide dans des gouttes à l’échelle microfluidique

There are several incentives to introduce microfluidic technology in the field of liquid liquid extraction: portabiliby, small sample size outstanding flow control, fast exchanges are advantages that may be exploited to design new efficient systems dedicated to the treatment of moderate volumes, or to screen many physico chemical conditions so as to optimize existing systems. Thus far, a limited number of systems have been considered: microfluidic coflow geometries, segmented flow or droplets trapped in microchambers. Here we concentrate on emulsion solvent extraction investigated in a microfluidic format.
We thus analyse aqueous droplets moving in microchannels and performing extraction: fluorescein afrom an organic phase (octanol) and the reactive extraction of Zn2+ from an aqueous phase. Additionally, we perform 2D numerical simulations. The influence of different parameters is analysed (microchannel dimensions, fluid viscosities, flow rates, drop size, droplet spacing…). Several extraction regimes are singled out. The time to perform extraction is found to agree with low Reynolds number transfer theory and with the numerical simulation. In practice, it takes a few seconds to perform extraction in this system which is much faster than in conventional systems.

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