“Colloid 2000”
Lehigh University, Bethlehem, Pennsylvania
June 19-21, 2000

Sponsored by the American Chemical Society Division of Colloid and Surface Chemistry

Authors of Paper:
D. Eric Aston, John C. Berg, Dept. of Chemical Engineering, University of Washington, Box 351750, Seattle, WA, 98195-1750, USA
Title of Paper:  COLLOID FORCES AT OIL-WATER INTERFACES WITH AFM.

Abstract: The interactions of silanated-glass and polystyrene microspheres (5-20 mm) with oil-water interfaces are observed using atomic force microscopy (AFM) and interpreted in light of extended DLVO theory for systems expected to exhibit long-range hydrophobic attractions.  Successful deconvolution of force-distance data for these poorly constrained systems is accomplished through electrolyte titration of double layer forces and careful consideration of the conforming interface.  The effects of electrolyte concentration, adsorbed polymer, and unperturbed interfacial curvature on film stability, drainage and rupture (wetting), and particle detachment are quantified.  Actual surface separation is deduced from theoretical relationships for interfacial displacement and fitted with semi-empirical, nonlinear correlations for closed-form calculations.  These experiments are directed toward understanding the behavior of oil-assisted agglomeration as applied to toner-printed paper recycling, mineral flotation, mixed waste separation, plastics recycling, and other dispersion related processes.