Selective solvent evaporation from binary mixtures of water and tetrahydrofuran using a falling film microreactor

In this work, a falling film micro reactor was investigated regarding its ability to continuously eliminate tetrahydrofuran (THF) out of a THF-water mixture via nitrogen stripping. Mass transfer measurements were performed at different temperatures and flow rates. The residual content of THF in the eluate was quantified with high precision (<0.1%) via density measurements. Remarkably, complete elimination of THF could be achieved for liquid volume flow rates smaller than 2 ml/min and nitrogen volume flow rates larger than 400 ml/min at all three investigated temperatures (55°C, 60°C, and 65°C). In order to assist future design processes of such binary microstripping systems, we further developed a mass transfer model for this separation process extending an existing model for evaporation of a pure liquid. The good agreement of experimental data and calculations in the overall investigated parameter range (<20%, for gas flow rates below 500 ml/min <11%) shows the potential of the model for the prediction of alternative operational parameter settings, e.g. at different THF entrance concentrations.