Attachment efficiencies of rough, angular, methylated quartz particles with
nitrogen bubbles are derived from experimental capture efficiency data in
conjunction with a collision model termed the Generalized Sutherland Equati
on (GSE). The methylated quartz particles ranged in size from 7.5 to 70 mu
m equivalent diameter and had advancing contact angles between 33 degrees a
nd 74 degrees. They heterocoagulated with nitrogen bubbles between 0.77 and
1.52 mm in diameter in 0, 0.01, or 0.1 mol dm(-3) KCl. The attachment effi
ciencies decreased with increasing particle size and bubble size, but incre
ased with particle contact angle and KCl electrolyte concentration. These a
ttachment efficiency data were then used to test the Dobby-Finch attachment
model for potential flow conditions. The latter model was modified so that
the conditions of approach of the particle toward the bubble surface are t
he same as those defined previously in the GSE collision model (Dai et at,
1998, J. Colloid Interface Sci. 197, 275). Satisfactory agreement was obtai
ned between the experimental attachment efficiencies obtained in this study
and those calculated with the Dobby-Finch model. In the attachment efficie
ncy calculations, the induction time (t(ind)) varied with particle size (d(
p)) according to the well-known equation, t(ind) = Ad(p)(B). The parameter
B, with a value of 0.6, was found to be independent of particle size, parti
cle contact angle, bubble size, and KCl electrolyte concentration. Converse
ly, the value of the parameter A was dependent on the particle contact angl
e, especially for contact angles smaller than 50 degrees, and on the bubble
size but to a lesser extent on the electrolyte concentration. The value of
A decreased with an increase in particle contact angle and an increase in
bubble size. The values of the induction time obtained in this study are in
a reasonable agreement with experimental and calculated induction times re
ported in the literature. (C) 1999 Academic Press.