title: Phase and sedimentation behavior of oil (octane) dispersions in the presence of model mineral aggregates.
abstract: Adsorption of suspended particles to the interface of surfactant-dispersed oil droplets can alter emulsion phase and sedimentation behavior. This work examines the effects of model mineral aggregates (silica nanoparticle aggregates or SNAs) on the behavior of oil (octane)-water emulsions prepared using sodium bis(2-ethylhexyl) sulfosuccinate (DOSS). Experiments were conducted at different SNA hydrophobicities in deionized and synthetic seawater (SSW), and at 0.5mM and 2.5mM DOSS. SNAs were characterized by thermogravimetric analysis (TGA) and dynamic light scattering (DLS), and the emulsions were examined by optical and cryogenic scanning electron microscopy. In deionized water, oil-in-water emulsions were formed with DOSS and the SNAs did not adhere to the droplets or alter emulsion behavior. In SSW, water-in-oil emulsions were formed with DOSS and SNA-DOSS binding through cation bridging led to phase inversion to oil-in-water emulsions. Droplet oil-mineral aggregates (OMAs) were observed for hydrophilic SNAs, while hydrophobic SNAs yielded quickly sedimenting agglomerated OMAs.
authors.affiliation: Department of Chemistry & Biology, Department of Engineering, Mathematics, and Physics, Texas A&M International University, 5201 University Blvd, Laredo, TX 78041, United States.
authors.forename: Anju
authors.initials: A
authors.lastname: Gupta
authors.affiliation: Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd, Kingston, RI 02881, United States.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Sender
authors.affiliation: Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd, Kingston, RI 02881, United States.
authors.forename: Sarah
authors.initials: S
authors.lastname: Fields
authors.affiliation: Department of Chemical Engineering, University of Rhode Island, 16 Greenhouse Rd, Kingston, RI 02881, United States. Electronic address: bothun@egr.uri.edu.
authors.forename: Geoffrey D
authors.initials: GD
authors.lastname: Bothun
mesh_terms: D000327:Adsorption; D004143:Dioctyl Sulfosuccinic Acid; D004655:Emulsions; D057927:Hydrophobic and Hydrophilic Interactions; D053758:Nanoparticles / Q000737:chemistry*; D009795:Octanes / Q000737:chemistry*; D012623:Seawater / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D004655:Emulsions; D009795:Octanes; D013501:Surface-Active Agents; D004143:Dioctyl Sulfosuccinic Acid; D012822:Silicon Dioxide; C026728:octane
keywords: AOT; DOSS; Oil dispersion; Oil–mineral aggregates; Silica nanoparticles