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Abstract
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In this work, application of silica nanoparticles for wettability
alteration of initially oil-wet calcite was investigated through analysis of
surface forces and DLVO theory. Doing so, the wettability and zeta potential
of calcite surfaces were measured through the sessile drop method and an inhouse
experimental setup, respectively. Primary evaluation indicated that
incorporating DLVO terms in the Frumkin?Derjaguin model was not
sufficient to describe the wettability in an oil-wet calcite/nanofluid system.
Sensitivity analysis showed that calculating the double-layer interaction using
constant potential-constant potential boundaries along with structural
hydrophobic forces (non-DLVO interaction) incorporation improved the
modeling performance. Considering hydrophobic interactions through linear correlation between hydrophobicity and
wettability change for both single-exponential and harmonic equations provided some confidence on the modeling approach.
Moreover, structural forces were suggested to be introduced as a combination of hydrophobic/hydrophilic interactions
corresponding to stearic acid-coated/silica nanoparticle-covered sites, respectively; which in turn demonstrated a successful
prediction of measured wettability data.
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