(142ad) Microfluidic Generation of Ultra-Thin Oil Film On Inertia Bubble for the Enhancement of Microextraction At High Phase Ratio

Liquid-liquid extraction process plays very important role in chemical engineering processes. During recent years, microfluidic technologies have become effective tools to realize on-line microextraction or give fundamental study of mass transfer process at micrometer scale. For the mass transfer enhancement of liquid-liquid extraction process in microchannel at high phase ratio (Q_C/Q_D >10), inertia gas phase is added to the liquid-liquid system to form gas-in-oil-in-water styled microflow system in this work. The gas phase is injected in the dispersed oil by a dual-coflowing microfluidic device to help increase the phase ratio of dispersed phase and prepare ultra-thin oil films on inertia bubbles with thicknesses ranging from 0.3 μm to 4.1 μm, which can significantly reduce the mass transfer distance in the oil extractant. The mass transfer enhancing effect of this gas-in-oil-in-water styled microflow system is characterized by extracting Sudan Red IV from SDS-PVA-aqueous solution to PDMS-alkane solution and the results indicated the extraction efficiency of this gas-in-oil-in-water system is tens of times higher than the common oil-in-water system.