Experimental quantification of interfacial convections at the water–nonaqueous‐phase liquid interface in microfluidic systems

Abstract Mass transfer rates at liquid–liquid interfaces are relevant for a broad range of processes in natural and technical systems. The objective this study was to characterize quantify convective flow along the interface between water nonaqueous‐phase liquids (NAPLs). Three NAPLs with different solubility were used: 1‐heptanol, 1‐octanol, 1‐nonanol. visualized recorded micromodel setup fluorescent particles an epifluorescence microscope. Individual trajectories evaluated obtain statistics particle velocities. We observed fast‐rotating convection current NAPL–water maximum velocity approximately 1,000 μm s −1 after 10 min. fluid motion showed persistent movement form rolling cell least 99 h, but decreasing rotation speed over time. attributed dynamics three mechanisms following kinetic rates: (a) short‐lived Marangoni flow, (b) medium‐lived dissolution‐driven (c) long‐lived evaporation‐driven flow. Upon initial contact NAPLs, differences surface tension caused rapid interface, which died out quickly as tensions equilibrated. superseded by dissolved aqueous phase. dissipated according first‐order rate law when mutually saturated. Evaporation long‐term slow interaction these enhanced mixing during multiphase transport.