J. Nalaskowski et al., Interactions between fossil resin and coal in the presence of anionic and cationic surfactants, COLL SURF A, 154(1-2), 1999, pp. 103-113
Citations number
32
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
Interaction forces between resin spheres and a polished coal, surface were
measured by atomic force microscopy (AFM). Spherical resin particles, used
for these measurements, were obtained from naturally occurring fossil resin
present in Wasatch Plateau coal (Utah, USA) using a special preparation te
chnique. Force measurements were made in solutions of sodium dodecyl sulfat
e and dodecylamine hydrochloride as a function of concentration. Electropho
resis and transmittance studies of coal and resin suspensions were performe
d for the same conditions as for the force measurements. As expected, for b
oth surfactants, repulsive forces were observed. However, in 10(-5) M and 1
0(-4) M DDAH repulsive forces were not observed at distances from the surfa
ce beyond 10 nm. This concentration is very close to the point of zero char
ge (pzc) for resin and coal as determined by electrophoresis measurements.
The force/radius values versus separation distance were plotted against con
centration values as a 3D map. The trends observed were in very good agreem
ent with electrophoresis and transmittance plots. The results show that the
pzc and suspension stability can be estimated from AFM force measurements
even for non-ideal surfaces, as typically encountered in many industrial pr
ocesses. (C) 1999 Elsevier Science B.V. All rights reserved.