Liquid-liquid extraction based on droplet flow in a vertical microchannel

In this work, the flow patterns and mass transfer characteristics of immiscible fluids based on droplet flow in a vertical microchannel are investigated experimentally. Water-succinic acid-n-butanol is chosen for the working system. An opposite-flowing T-shaped microchannel has been proposed to form favourable monodispersed droplet flow in a wide range of volume flow rate ratio. Experiments were performed at volume flow rate ratios between 1.2 and 24, and droplet flow and plug flow were observed in the main channel. The droplet flow occurs at volume flow rate ratio of 3-24, and plug flow occurs at volume flow rate ratio of 1.2-2. For droplet flow regime, monodispersed organic droplets with average diameters of 123-532 mu m were generated, and the volumetric mass transfer coefficients were in the ranges of 0.012-0.082 s(-1). In addition, the effects of various operating conditions such as volume flow rate ratio, total flow velocity, and the inner diameter of the main channel on the droplet coalescence, average droplet diameter, extraction efficiency and volumetric mass transfer coefficient are also been studied. An empirical correlation is developed to predict the volumetric mass transfer coefficients. Crown Copyright (c) 2013 Published by Elsevier Inc. All rights reserved.