Preferential positioning and phase exposure of granular particles at hydrophobic liquid-water interface

Abstract

The positioning of granular limestone and quartz particles at the hydrophobic liquid-water interfaces was evaluated and compared experimentally and analyzed by the theoretical analyses by considering the electrostatic interaction and gravitational effects. Experiments were performed with light hydrophobic liquids (tetradecane, silicone oil with viscosities 10 and 100 cSt, and South Louisiana crude oil) which were submerged by granular limestone and quartz with different particle sizes (average particle radius 0.25, 0.10, <0.004 mm). The particles of similar size but different materials (i.e., limestone, quartz) exhibited noticeably different behavior within the hydrophobic phase and in their positioning and transport towards the hydrophobic liquid-water interface. The comparison of the dimensionless Bond number for the systems evaluated showed discrepancies between the Bond number theory and experimental observations. The preferential behavior of less than millimeter sized granular particles at the hydrophobic liquid-water interface was found to be predominantly affected by the electrostatic force only.