Settling in aggregating colloidal suspension: Analysis of cell inclination influence
D. Senis - L. Gorre-Talini - C. Allain
Laboratoire FAST, Bât. 502 - Campus Universitaire,
91405 Orsay Cedex, France
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Received 13 July 1999
Abstract
We present the study of the settling of a colloidal gel
in a cell tilted at an angle 
.
In suspensions of non-colloidal
particles, the inclination of the sedimentation cell
leads to a large enhancement of the settling velocity known as
"Boycott effect'' well described by the PNK model. We show that
the specific mechanical properties of a colloidal gel can give way
to kinetics of settling very different from usual suspensions
which can no longer be described using a simple PNK model. In
particular, we study the influence of the very voluminous sediment
generally formed in such systems. We thus propose a complete
description of the kinetics of a settling colloidal gel according
to its volume fraction and to the cell inclination angle. In the
experimental section, the predicted settling regimes are compared
to experimental results obtained with calcium carbonate
suspensions. The agreement between theoretical expressions and
experiments is good which shows that our results are relevant to
most experimental studies of tenuous colloidal gels.
PACS
82.70.Dd Colloids - 47.20.Bp Buoyancy-driven
instability
Copyright EDP Sciences, Società Italiana di Fisica, Springer-Verlag
