Ultra-thin liquid film extraction based on a gas–liquid–liquid double emulsion in a microchannel device

Abstract

A new microfluidic extraction method using a gas–liquid–liquid double emulsion with ultra-thin solvent film as the working system was developed, overcoming the defect of low extraction efficiency at extreme phase ratios (R > 10) by significantly reducing the mass transfer distance. Interesting bubble coalescence in the emulsion generation was reported and laws of bubble diameter (0.73–1.08 mm) and film thickness (0.35–4.06 μm) were proposed. Simulated by a Sudan IV extraction process, the gas–liquid–liquid extraction showed 16–28.3 times working efficiency compared to liquid–liquid extraction, appropriate for application requiring fast analysis and detection.