(55p) Electrocoalescence of Water-Oil Mixtures Induced By Corona Discharge

Commercially available methods of oil/water separation are mostly energy inefficient, time consuming, and costly. This study considers a contactless method of electrocoalescence via corona discharge. Using a pin-to-plate configuration and pure/pulsed DC sources, non­–uniform electric fields form which generate corona discharges. Applying the corona discharge to oil/water mixture results in a smooth separation of the two distinct phases. Considering the different processing parameters, it is possible to tune the effect of effective forces, i.e. electrophoresis or migratory coalescence (EP), dipole–dipole interaction (DDI), etc., acting on water droplets to facilitate the separation process. It is observed that the corona discharge significantly enhances the coalescence in concentrated W/O emulsions (made with silicone oil 350 cSt and 2 wt.% water content). After only 120 seconds of processing, it is observed that the two phases were separated into nearly two distinct phases. In the second part of the study, the effect of corona discharge on coalescence rate of water droplets in silicone oil 3000 cSt were investigated. Depending on the initial distance between the water droplets, coalescence could occur due to DDI for close distances or EP for far away droplets. For the case of DDI, it is shown that pulsed DC fields are preferred rather than pure DC. The coalescence times measured were 7, 3, 6, and 18 seconds for pure DC and pulsed DC with frequencies of 1, 10, and 20 Hz. For the case of EP, it was observed that pure DC performs better with coalescence times of 20, 40, 29, and 80 seconds for pure DC and pulsed DC in frequencies of 1, 10, and 20 Hz.