title: Stabilization of carbon dioxide-in-water emulsions with silica nanoparticles.
abstract: Stable carbon dioxide-in-water emulsions were formed with silica nanoparticles adsorbed at the interface. The emulsion stability and droplet size were characterized with optical microscopy, turbidimetry, and measurements of creaming rates. The increase in the emulsion stability as the silica particle hydrophilicity was decreased from 100% SiOH to 76% SiOH is described in terms of the contact angles and the resulting energies of attachment for the silica particles at the water-CO(2) interface. The emulsion stability also increased with an increase in the particle concentration, CO(2) density, and shear rate. The dominant destabilization mechanism was creaming, whereas flocculation, coalescence, and Ostwald ripening played only a minor role over the CO(2) densities investigated. The ability to stabilize these emulsions with solid particles at CO(2) densities as low as 0.739 g/mL is particularly relevant in practical applications, given the difficulty in stabilizing these emulsions with surfactants, because of the unusually weak solvation of the surfactant tails by CO(2).
authors.affiliation: Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA.
authors.forename: Jasper L
authors.initials: JL
authors.lastname: Dickson
authors.forename: Bernard P
authors.initials: BP
authors.lastname: Binks
authors.forename: Keith P
authors.initials: KP
authors.lastname: Johnston
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004655:Emulsions / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D004655:Emulsions; D014867:Water; D002245:Carbon Dioxide; D012822:Silicon Dioxide