"Combined Experimental and Molecular Simulation Investigation of the In" by Zenghui Zhang, Paria Avij et al.

Faculty Publications

Title

Combined Experimental and Molecular Simulation Investigation of the Individual Effects of Corexit Surfactants on the Aerosolization of Oil Spill Matter

Authors

Zenghui Zhang, Cain Department of Chemical Engineering, Louisiana State University , Baton Rouge, Louisiana 70803, United States.
Paria Avij, Cain Department of Chemical Engineering, Louisiana State University , Baton Rouge, Louisiana 70803, United States.
Matt J. Perkins, Department of Environmental & Molecular Toxicology, Oregon State University , Corvallis, Oregon 97331, United States.
Thilanga P. Liyana-Arachchi, Department of Chemistry, University of Florida , Gainesville, Florida 32611, United States.
Jennifer A. Field, Department of Environmental & Molecular Toxicology, Oregon State University , Corvallis, Oregon 97331, United States.
Kalliat T. Valsaraj, Cain Department of Chemical Engineering, Louisiana State University , Baton Rouge, Louisiana 70803, United States.
Francisco R. Hung, Cain Department of Chemical Engineering, Louisiana State University , Baton Rouge, Louisiana 70803, United States.

Document Type

Article

Publication Date

8-4-2016

Abstract

We report laboratory aerosolization experiments and classical molecular dynamics (MD) simulations, with the objective of investigating the individual effects of the two Corexit surfactants Span 80 (nonionic) and dioctyl sodium sulfosuccinate (DOSS, ionic), on the aerosolization of oil spill matter to the atmosphere. Our simulation results show that Span 80, DOSS, and the oil alkanes n-pentadecane (C15) and n-triacontane (C30) exhibit deep free energy minima at the air/seawater interface. C15 and C30 exhibit deeper free energy minima at the interface when Span 80 is present, as compared to the situation when DOSS or no surfactants are at the interface. These results suggest that Span 80 makes these oil hydrocarbons more likely to be adsorbed at the surface of seawater droplets and carried out to the atmosphere, relative to DOSS or to the situation where no surfactants are present. These simulation trends are in qualitative agreement with our experimental observations in a bubble-column setup, where larger amounts of oil hydrocarbons are ejected when Span 80 is mixed with oil and injected into the column, as compared to when DOSS is used. Our simulations also indicate that Span 80 has a larger thermodynamic incentive than DOSS to move from the seawater phase and into the air/seawater interface. This observation is also in qualitative agreement with our experimental measurements, which indicate that Span 80 is ejected in larger quantities than DOSS. Our simulations also suggest that DOSS predominantly adopts a perpendicular orientation with respect to the air/seawater interface at a dispersant to oil ratio (DOR) of 1:20, but has a slight preference to lie parallel to the interfaces at a DOR = 1:5; in both cases, DOSS molecules have their tails wide open and stretched. In contrast, Span 80 has a slight preference to align parallel to the interfaces with a coiled conformation at both DOR values.

Publication Source (Journal or Book title)

The journal of physical chemistry. A

First Page

6048

Last Page

Recommended Citation

Zhang, Z., Avij, P., Perkins, M. J., Liyana-Arachchi, T. P., Field, J. A., Valsaraj, K. T., & Hung, F. R. (2016). Combined Experimental and Molecular Simulation Investigation of the Individual Effects of Corexit Surfactants on the Aerosolization of Oil Spill Matter. The journal of physical chemistry. A, 120 (30), 6048-58. https://doi.org/10.1021/acs.jpca.6b04988

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