title: Modified montmorillonite clay microparticles for stable oil-in-seawater emulsions.
abstract: Environmentally benign clay particles are of great interest for the stabilization of Pickering emulsions. Dodecane-in-synthetic seawater (SSW) emulsions formed with montmorillonite (MMT) clay microparticles modified with bis(2-hydroxyethyl)oleylamine were stable against coalescence, even at clay concentrations down to 0.1% w/v. Remarkably, as little as 0.001% w/v surfactant lowered the hydrophilicity of the clay to a sufficient level for stabilization of oil-in-SSW emulsions. The favorable effect of SSW on droplet size reduction and emulsion stability enhancement is hypothesized to be due to reduced electrostatic repulsion between adsorbed clay particles and a consequent increase in the continuous phase (an aqueous clay suspension) viscosity. Water/oil (W/O) emulsions were inverted to O/W either by decreasing the mass ratio of surfactant-to-clay (transitional inversion) or by increasing the water volume fraction (catastrophic inversion). For both types of emulsions, coalescence was minimal and the sedimentation or creaming was highly correlated with the droplet size. For catastrophic inversions, the droplet size of the emulsions was smaller in the case of the preferred curvature. Suspensions of concentrated clay in oil dispersions in the presence of surfactant were stable against settling. The mass transfer pathways during emulsification of oil containing the clay particles were analyzed on the droplet size/stability phase diagrams to provide insight for the design of dispersant systems for remediating surface and subsurface oceanic oil spills.
authors.affiliation: McKetta Department of Chemical Engineering, ‡Department of Chemistry and Biochemistry, and §Department of Petroleum and Geosystems Engineering, The University of Texas at Austin , Austin, Texas 78712-0231, United States.
authors.forename: Jiannan
authors.initials: J
authors.lastname: Dong
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Worthen
authors.forename: Lynn M
authors.initials: LM
authors.lastname: Foster
authors.forename: Yunshen
authors.initials: Y
authors.lastname: Chen
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Cornell
authors.forename: Steven L
authors.initials: SL
authors.lastname: Bryant
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Truskett
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Bielawski
authors.forename: Keith P
authors.initials: KP
authors.lastname: Johnston