LAUSR

Abstract We present a visualized measurement of the transient Marangoni effect occurring in interfacial mass transfer processes by using a planner laser-induced fluorescence (PLIF) technique. Since acidity increased remarkably and linearly the fluorescent intensity of Rhodamine B, the concentration distribution of acidic solute inside a drop was obtained by PLIF. Thus, based on the concentration contours of solute, we could probe into the bulk flow and occurrence of the Marangoni effect. The Marangoni effect has been known to be affected by the physical properties of the test system, initial solute concentration, the operating conditions and device configurations. With existence of neutralization reaction in the extraction system, the Marangoni effect was declined as for the acetic acid being consumed rapidly. Last, we found that the density effect of solute coupled with Marangoni effect, which further affected the distribution of solute and then influenced the location and evolution of Marangoni effect.