title: Ion adsorption-induced wetting transition in oil-water-mineral systems.
abstract: The relative wettability of oil and water on solid surfaces is generally governed by a complex competition of molecular interaction forces acting in such three-phase systems. Herein, we experimentally demonstrate how the adsorption of in nature abundant divalent Ca(2+) cations to solid-liquid interfaces induces a macroscopic wetting transition from finite contact angles (≈ 10°) with to near-zero contact angles without divalent cations. We developed a quantitative model based on DLVO theory to demonstrate that this transition, which is observed on model clay surfaces, mica, but not on silica surfaces nor for monovalent K(+) and Na(+) cations is driven by charge reversal of the solid-liquid interface. Small amounts of a polar hydrocarbon, stearic acid, added to the ambient decane synergistically enhance the effect and lead to water contact angles up to 70° in the presence of Ca(2+). Our results imply that it is the removal of divalent cations that makes reservoir rocks more hydrophilic, suggesting a generalizable strategy to control wettability and an explanation for the success of so-called low salinity water flooding, a recent enhanced oil recovery technology.
authors.affiliation: University of Twente, MESA+ Institute for Nanotechnology, Physics of Complex Fluids, P.O. Box 217, 7500AE Enschede (The Netherlands).
authors.forename: Frieder
authors.initials: F
authors.lastname: Mugele
authors.affiliation: University of Twente, MESA+ Institute for Nanotechnology, Physics of Complex Fluids, P.O. Box 217, 7500AE Enschede (The Netherlands).
authors.forename: Bijoyendra
authors.initials: B
authors.lastname: Bera
authors.affiliation: University of Twente, MESA+ Institute for Nanotechnology, Physics of Complex Fluids, P.O. Box 217, 7500AE Enschede (The Netherlands).
authors.forename: Andrea
authors.initials: A
authors.lastname: Cavalli
authors.affiliation: University of Twente, MESA+ Institute for Nanotechnology, Physics of Complex Fluids, P.O. Box 217, 7500AE Enschede (The Netherlands).
authors.forename: Igor
authors.initials: I
authors.lastname: Siretanu
authors.affiliation: University of Twente, MESA+ Institute for Nanotechnology, Physics of Complex Fluids, P.O. Box 217, 7500AE Enschede (The Netherlands).
authors.forename: Armando
authors.initials: A
authors.lastname: Maestro
authors.affiliation: University of Twente, MESA+ Institute for Nanotechnology, Physics of Complex Fluids, P.O. Box 217, 7500AE Enschede (The Netherlands).
authors.forename: Michel
authors.initials: M
authors.lastname: Duits
authors.affiliation: University of Twente, MESA+ Institute for Nanotechnology, Physics of Complex Fluids, P.O. Box 217, 7500AE Enschede (The Netherlands).
authors.forename: Martien
authors.initials: M
authors.lastname: Cohen-Stuart
authors.affiliation: University of Twente, MESA+ Institute for Nanotechnology, Physics of Complex Fluids, P.O. Box 217, 7500AE Enschede (The Netherlands).
authors.forename: Dirk
authors.initials: D
authors.lastname: van den Ende
authors.affiliation: BP Exploration Operation Company Ltd., Chertsey Road, Sunbury-on-Thames, TW16 7LN, (United Kingdom).
authors.forename: Isabella
authors.initials: I
authors.lastname: Stocker
authors.affiliation: BP Exploration Operation Company Ltd., Chertsey Road, Sunbury-on-Thames, TW16 7LN, (United Kingdom).
authors.forename: Ian
authors.initials: I
authors.lastname: Collins