title: Interfacial adsorption and surfactant release characteristics of magnetically functionalized halloysite nanotubes for responsive emulsions.
abstract: Magnetically responsive oil-in-water emulsions are effectively stabilized by a halloysite nanotube supported superparamagnetic iron oxide nanoparticle system. The attachment of the magnetically functionalized halloysite nanotubes at the oil-water interface imparts magnetic responsiveness to the emulsion and provides a steric barrier to droplet coalescence leading to emulsions that are stabilized for extended periods. Interfacial structure characterization by cryogenic scanning electron microscopy reveals that the nanotubes attach at the oil-water interface in a side on-orientation. The tubular structure of the nanotubes is exploited for the encapsulation and release of surfactant species that are typical of oil spill dispersants such as dioctyl sulfosuccinate sodium salt and polyoxyethylene (20) sorbitan monooleate. The magnetically responsive halloysite nanotubes anchor to the oil-water interface stabilizing the interface and releasing the surfactants resulting in reduction in the oil-water interfacial tension. The synergistic adsorption of the nanotubes and the released surfactants at the oil-water interface results in oil emulsification into very small droplets (less than 20μm). The synergy of the unique nanotubular morphology and interfacial activity of halloysite with the magnetic properties of iron oxide nanoparticles has potential applications in oil spill dispersion, magnetic mobilization and detection using magnetic fields.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA 70118, USA.
authors.forename: Olasehinde
authors.initials: O
authors.lastname: Owoseni
authors.affiliation: Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Nyankson
authors.affiliation: Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA 70118, USA.
authors.forename: Yueheng
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Advanced Materials Research Institute, University of New Orleans, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Adams
authors.affiliation: Coordinated Instrumentation Facility, Tulane University, New Orleans, LA 70118, USA.
authors.forename: Jibao
authors.initials: J
authors.lastname: He
authors.affiliation: Advanced Materials Research Institute, University of New Orleans, USA.
authors.forename: Leonard
authors.initials: L
authors.lastname: Spinu
authors.affiliation: Department of Chemistry, Tulane University, New Orleans, LA 70118, USA.
authors.forename: Gary L
authors.initials: GL
authors.lastname: McPherson
authors.affiliation: Department of Chemical Engineering, University of Rhode Island, Kingston, RI 02881, USA.
authors.forename: Arijit
authors.initials: A
authors.lastname: Bose
authors.affiliation: Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.
authors.forename: Ram B
authors.initials: RB
authors.lastname: Gupta
authors.affiliation: Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA 70118, USA. Electronic address: vj@tulane.edu.
authors.forename: Vijay T
authors.initials: VT
authors.lastname: John
keywords: Emulsion; Encapsulation; Halloysite nanotubes; Interfacial tension; Iron oxide; Magnetic responsiveness; Release; Surfactant