(698b) Modeling of Interfacial Properties and Interfacial Mass Transfer in Liquid-Liquid Extraction Systems
AIChE Annual Meeting
2019 AIChE Annual Meeting
Engineering Sciences and Fundamentals
Modeling of Interfacial Systems
Thursday, November 14, 2019 - 12:30pm to 12:45pm
In this work the influence of the target component on interfacial properties and interfacial mass transport in ternary liquid-liquid extraction systems is analyzed. The mass transfer across a liquid-liquid interface is governed by the liquid-liquid equilibrium (LLE) and the interfacial tension, hence, both properties have to be studied. The well-documented system water + toluene + acetone is chosen as a reference system . The target component, acetone, is then replaced by other molecules differing in size, polarity and structure. For this study, ethanol, tetrahydrofuran and acetonitrile are studied as other target components. Tie lines for the LLE of water + toluene + ethanol, water + toluene + tetrahydrofuran and water + toluene + acetonitrile are determined. The interfacial tension for the chosen tie lines is analyzed by the spinning drop method. Subsequently, mass transfer experiments are conducted in a Nitsch cell. Several experiments with different starting compositions are performed.
The experimental results are used to model the interfacial mass transfer applying the Density Gradient Theory (DGT) . For that purpose, the DGT is coupled with the Koningsveld-Kleintjens (KK) model as a gE-model . The model parameters of the KK model are fitted to the LLE of the respective ternary system. Stationary DGT is applied to calculate the interfacial tension and interfacial concentration profile for different equilibrium compositions of the ternary mixtures. These calculations predict different enrichment of the target components at the interface. Based on the equilibrium calculations the time dependent concentration profile is modeled by instationary DGT. Furthermore, interfacial properties for quaternary systems containing two of the studied molecules as target components in a water + toluene system are predicted. For that purpose, the DGT and KK model are extended to describe quaternary systems .
The experimental results are compared with previously conducted mass transfer experiments with acetone as the target component . Based on the predicted interfacial concentration profiles and experimental results for the interfacial mass transfer the influence of different target components can be discussed.
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