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.