Impact of gravity, collector surface roughness and fracture orientation on colloid retention kinetics in an artificial fracture

[Display omitted] The interaction of monodisperse fluorescent carboxylated polystyrene colloids (25nm and 1000nm diameter) with a cut granodiorite surface (Grimsel granodiorite; Switzerland) and with acrylic glass is investigated both experimentally and numerically. Colloid transport experiments are...

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Bibliographic Details
Published in:Journal of colloid and interface science 2016-08, Vol.475, p.171-183
Main Authors: Stoll, M., Huber, F.M., Darbha, G.K., Schill, E., Schäfer, T.
Format: Article
Language:English
Subjects:
Accumulators
Carboxylated latex spheres
Collectors
Colloid transport
Colloids
Fracture
Fracture mechanics
Mathematical models
Modeling
Orientation
Sedimentation
Surface roughness
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Summary:[Display omitted] The interaction of monodisperse fluorescent carboxylated polystyrene colloids (25nm and 1000nm diameter) with a cut granodiorite surface (Grimsel granodiorite; Switzerland) and with acrylic glass is investigated both experimentally and numerically. Colloid transport experiments are conducted in a parallel plate type fracture flow cell with an aperture of 0.75mm at pH5 under low ionic strength (1mM NaCl) and under laminar flow (7mL/h) conditions. The study focuses on the effect of residence time, colloid size, collector material and fracture orientation on colloid retention. Long colloid residence times are achieved by stop-flow experiments. Using atomic force microscopy and, more specifically, the colloid probe technique surface roughness and force distance information of the collector material (granodiorite or acrylic glass) as a function of probe size (cantilever) are obtained. The experiments are modeled using COMSOL Multiphysics® (2-D numerical simulations). The experimental and the modeled results lead to the conclusion that large colloids (1000nm diameter) undergo sedimentation and deposition on the surface during stop-flow. Collector interaction is not affected by the surface roughness variation. Contrariwise, for the investigated 25nm colloids sedimentation does not play a role under the experimental conditions and collector interaction is triggered by surface inhomogeneities such as surface roughness.
ISSN:0021-9797
1095-7103
DOI:10.1016/j.jcis.2016.04.045