Olasehinde Owoseni1, Yueheng Zhang1, Marzhana Omarova1, Xin Li2, Jyotsana Lal2, Gary L McPherson3, Srinivasa R Raghavan4, Arijit Bose5, Vijay T John6. 1. Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA 70118, USA. 2. Louisiana Consortium for Neutron Scattering, Louisiana State University, Baton Rouge, LA 70803, USA. 3. Department of Chemistry, Tulane University, New Orleans, LA 70118, USA. 4. Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD 20742, USA. 5. Department of Chemical Engineering, University of Rhode Island, Kingston, RI 02881, USA. 6. Department of Chemical and Biomolecular Engineering, Tulane University, New Orleans, LA 70118, USA. Electronic address: vj@tulane.edu.
Abstract
HYPOTHESIS: Polyoxyethylene (20) sorbitan monooleate (Tween 80) can be incorporated into the gel-like phase formed by L-α-phosphatidylcholine (PC) and dioctyl sulfosuccinate sodium salt (DOSS) for potential application as a gel-like dispersant for oil spill treatment. Such gel-like dispersants offer advantages over existing liquid dispersants for mitigating oil spill impacts. EXPERIMENTS: Crude oil-in-saline water emulsions stabilized by the surfactant system were characterized by optical microscopy and turbidity measurements while interfacial tensions were measured by the spinning drop and pendant drop techniques. The microstructure of the gel-like surfactant mesophase was elucidated using small angle neutron scattering (SANS), cryo scanning electron microscopy (cryo-SEM), and 31P nuclear magnetic resonance (NMR) spectroscopy. FINDINGS: The gel-like phase consisting of PC, DOSS and Tween 80 is positively buoyant on water and breaks down on contact with floating crude oil layers to release the surfactant components. The surfactant mixture effectively lowers the crude oil-saline water interfacial tension to the 10-2 mN/m range, producing stable crude oil-in-saline water emulsions with an average droplet size of about 7.81 µm. Analysis of SANS, cryo-SEM and NMR spectroscopy data reveals that the gel-like mesophase has a lamellar microstructure that transition from rolled lamellar sheets to onion-like, multilamellar structures with increasing Tween 80 content.
HYPOTHESIS: Polyoxyethylene (20) sorbitan monooleate (Tween 80) can be incorporated into the gel-like phase formed by L-α-phosphatidylcholine (PC) and dioctyl sulfosuccinate sodium salt (DOSS) for potential application as a gel-like dispersant for oil spill treatment. Such gel-like dispersants offer advantages over existing liquid dispersants for mitigating oil spill impacts. EXPERIMENTS: Crude oil-in-salinewater emulsions stabilized by the surfactant system were characterized by optical microscopy and turbidity measurements while interfacial tensions were measured by the spinning drop and pendant drop techniques. The microstructure of the gel-like surfactant mesophase was elucidated using small angle neutron scattering (SANS), cryo scanning electron microscopy (cryo-SEM), and 31P nuclear magnetic resonance (NMR) spectroscopy. FINDINGS: The gel-like phase consisting of PC, DOSS and Tween 80 is positively buoyant on water and breaks down on contact with floating crude oil layers to release the surfactant components. The surfactant mixture effectively lowers the crude oil-salinewater interfacial tension to the 10-2 mN/m range, producing stable crude oil-in-salinewater emulsions with an average droplet size of about 7.81 µm. Analysis of SANS, cryo-SEM and NMR spectroscopy data reveals that the gel-like mesophase has a lamellar microstructure that transition from rolled lamellar sheets to onion-like, multilamellar structures with increasing Tween 80 content.