Title page for ETD etd-06062008-154507
|Type of Document
||Flinn, Darrin Heinz
||Modeling bubble-particle interactions in flotation using hydrophobic solid surfaces
||Mining and Minerals Engineering
|Davis, Richey M.
|Luttrell, Gerald H.
|Rabionovich, Yokov I.
|Wightman, James P.
- using a geometric mean combining rule. Asymmetric
- K131 and K232
- can be predicted from those of the symmetric inter
- and infrared transmission spectra showed that OTS
- AFM images
- surface forcesAn atomic force microscope (AFM) was
|Date of Defense
An atomic force microscope (AFM) was used to measure surface forces
between a glass sphere and a flat fused silica plate under a number of conditions.
Hydrophobic surfaces exhibiting contact angles ranging from 0 to 109° were prepared
by reacting silica with octadecyltrichlorosilane (OTS). Contact angles, AFM images,
and infrared transmission spectra showed that OTS forms clusters on the silica surface.
The presence of water in the reaction was shown to greatly influence the formation of
these clusters. Forces were measured between surfaces coated with identical
(symmetric) and different (asymmetric) amounts of OTS to determine contributions
from hydrophobic forces. The results showed that the hydrophobic force parameters of
the asymmetric interactions, K132, can be predicted from those of the symmetric
interactions, K131 and K232, using a geometric mean combining rule. Asymmetric force
measurements were conducted between a hydrophobized glass sphere and a bare silica
plate in dodecylamine hydrochloride (DARCl) solutions as a function of pH in an effort
to simulate the forces involved in bubble-particle interactions for the quartz-amine
flotation system. The appearance of the hydrophobic force in these measurements
correlates well with the pH range of maximum flotation recoveries for quartz-amine
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