Influence of high-frequency AC fields on mass transfer in solvent extraction

The influence of high-frequency AC fields on mass transfer from aqueous pendant and moving droplets into a continuous organic phase is investigated. Results are compared with those of applied DC voltage and those with no electric field present. Experiments are carried out in a low viscosity water–toluene system with acetone as the solute and in a high viscosity water–isotridecanol system with 1-propanol as the solute. AC and DC effects on Marangoni phenomena at pendant droplets are studied. High-frequency AC voltage is found to depress Marangoni phenomena whereas DC voltage enhances or initially induces Marangoni phenomena. Mass transfer from moving droplets could not be enhanced by the use of electric fields (AC or DC) at constant droplet size. The experimentally achieved concentration–time profiles are compared with those calculated from different mass transfer models for single droplets.