A high aspect ratio membrane reactor for liquid–liquid extraction

In the present study, a high aspect ratio membrane reactor was evaluated in terms of extraction efficiency in co- and countercurrent flow using 2 different membrane types (Teflon® and polycarbonate). Using the parallel plate Poiseuille expression to approximate the flow profile in flat rectangular channels with high aspect ratios an analytical solution was established to describe the concentration profiles in the microcontactor for non-miscible mixtures, which was numerically and experimentally validated. Fast and uniform mass transfer could be enabled by providing ordered spacers of 100 and 200 μm in the reactor substrate. With the flow rates in this optimization being limited by the Laplace pressure of the membrane, a pressure driven alternative mimicked by adapting the flow rates inversely to the liquid viscosity ratios is analyzed and experimentally validated for co-current mode. Using the device in co-current mode, the system has the potential to serve as a fast screening tool to determine partition coefficients requiring 5–15 min per combination only. It was furthermore analyzed how the channel depth should be adapted when aiming to maximize the extracted mass. Similarly, also the optimal depth to achieve a preset concentration specification was analyzed.

► A high aspect ratio membrane micro-contactor is characterized.
► The mass transfer is described analytically and validated.
► Co- and counter-current extractions are experimentally performed and interpreted.
► Channel depths to reach maximum concentration or mass of analyte are derived.