ROLE OF SURFACE FREE-ENERGY IN A SOLID-SURFACE DURING COLLECTORLESS LIQUID-LIQUID-EXTRACTION

To determine the efficiency of liquid-liquid extraction for recovery of fine solid particles, the transfer of fine solid particles from a water phase to an oil/water interface, or to the oil phase, were investigated without using a collector. The tests were performed with solids of dissimilar hydrophobicity and n-heptane as the oil phase. High recovery levels of the solids having inherently hydrophobic surfaces were obtained. From contact-angle measurements and calculations of the surface free energies of the solids, the polar component of the surface free energy of the solid surface was found to govern the oil-solid adhesion, Moreover, the recovery levels of the collectorless liquid-liquid extraction method correlated with the work of adhesion, particularly, its polar component.