Intensification of mass transfer and reaction in electrically disturbed liquid-liquid systems

- Visualization of electrically induced disturbances during mass transfer.
- Promotion of electrically induced interfacial turbulence is accurately predicted.
- Evidence of time dependent mass transfer is confirmed.
- Simulations successfully match the visual disturbance patterns and rates observed.
- Electrostatic intensification of interfacial enzymatic activity demonstrated.

A new study of electrically induced disturbances and mass transfer at a liquid-liquid interface as a means of process intensification is presented. Visualization of electrically induced disturbances during mass transfer of ethanol from an aqueous phase into an extracting solvent, n-decanol is demonstrated. Mass transfer rates were measured for extraction of ethanol from an aqueous electrically charged pendant droplet into a continuous phase of n-decanol. In a second part, mass transfer rates of ethanol into n-decanol across a planar interface in the presence of a DC electrical field are presented. Thirdly, results are presented of electrostatic spraying of aqueous enzyme solutions into an immiscible triglyceride ester oil phase. The effect of electrical field on specific interfacial rate of reaction was determined. The first part of the study demonstrated the positive effect of electrical disturbance on mass transfer rate from the pendant droplet. Time dependent mass transfer was also shown, consistent with earlier mass transfer studies with uncharged pendant drops. The mass transfer study using the planar interface provided further confirmation of the positive effect of electrically induced interfacial turbulence on mass transfer. The experimental data are successfully compared with simulations based on rigorous numerical solutions of the controlling equations. The visual disturbance pattern at the interface and rates of mass transfer were accurately predicted. The reactor experiments clearly show a significant positive effect of electrical charge on the specific rate of hydrolysis. This latter finding opens up the possibility of intensification of enzymatic catalytic activity using electrical fields. The potential for electrically induced enhancement of other reaction systems involving liquid-liquid interfaces such as in the case of phase-transfer catalysis is highlighted.