Effects of high-pressure carbon dioxide on the demulsification of O/W emulsion

A new process for the demulsification of oil-in-water (O/W) emulsion with high-pressure carbon dioxide (CO₂) was proposed. For the confirmation of the concept, demulsification of O/W emulsion formed with a nonionic surfactant, Tween 20, was conducted. The behavior of O/W emulsion under high-pressure CO₂ was examined with a visual observation and an electrical conductivity measurement of the emulsions. Efficiency of the demulsification was evaluated by the oil content of water-rich phases and the amount of water-rich phases separated from the emulsion by the creaming of the oil phases. Experimental results revealed that the high-pressure CO₂ acts as a swelling reagent that lowers the density of the dispersed oil phase to induce the floatation of the oil droplet that leads to an efficient demulsification.