A core-annular liquid-liquid microextractor for continuous processing

A core-annular liquid-liquid microextractor (CALLME) has been applied to 10 vol% acetone-toluene and a mixture of alpha-methylbenzylamine/acetophenone-n-heptane extraction pairs as a robust screening tool for process development. In the CALLME, a stretchable helix wire was placed at the core position for the aqueous stream, and it was surrounded by the organic solvent to ensure a stable aqueous-organic contact interface. A theoretical governing equation for the operational pressure was formulated for device design. The CALLME has a large contact surface area and demonstrated > 90% extraction efficiency within 10 min. Further, we demonstrated its high operability in flow rate control, compatibility with different model systems, and scalability. Correlations relating the overall volumetric mass transfer coefficients to the residence time, flow rate ratio, and contact surface area are presented for both the CALLME and a bench-scale extraction continuous stirred-beaker reactor. The CALLME operates in a continuous flow mode, beneficial for rapid process characterization.