Effects of Frothers and Oil at Saltwater–Air Interfaces for Oil Separation: Molecular Dynamics Simulations and Experimental Measurements

Journal Article · 16 June 2017 · Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry

DOI: https://doi.org/10.1021/acs.jpcb.7b03313 · OSTI ID:1404700

Chong, Leebyn  ^[1]; Lai, Yungchieh ^[1]; Gray, McMahan ^[1]; Soong, Yee ^[1]; Shi, Fan ^[2]; Duan, Yuhua ^[1]

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1. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
2. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); AECOM, South Park, PA (United States)

Separating oil from saltwater is a process relevant to some industries and may be aided by bubble and froth generation. Simulating saltwater–air interfaces adsorbed with surfactants and oil molecules can assist in understanding froth stability to improve separation. Here, combining with surface tension experimental measurements, in this work we employ molecular dynamics with a united-atom force field to linear alkane oil and three surfactant frothers, methyl isobutyl carbinol (MIBC), terpineol, and ethyl glycol butyl ether (EGBE), to investigate their synergistic behaviors for oil separation. The interfacial phenomena were measured for a range of frother surface coverages on saltwater. Density profiles of the hydrophilic and hydrophobic portions of the frothers show an expected orientation of alcohol groups adsorbing to the polar water. A decrease in surface tension with increasing surface coverage of MIBC and terpineol was observed and reflected in experiments where the frother concentration increased. Relations between surface coverage and bulk concentration were observed by comparing the surface tension decreases. Additionally, a range of oil surface coverages was explored when the interface has a thin layer of adsorbed frother molecules. Finally, the obtained results indicate that an increase in surface coverage of oil molecules led to an increase in surface tension for all frother types and the pair correlation functions depicted MIBC and terpineol as having higher distributions with water at closer distances than with oil.

• Research Organization: National Energy Technology Lab. (NETL), Pittsburgh, PA, and Morgantown, WV (United States). In-house Research
• Sponsoring Organization: USDOE; US Department of the Interior, Bureau of Safety and Environmental Enforcement
• Grant/Contract Number: E15PG00032
• OSTI ID: 1404700
• Report Number(s): NETL-PUB-21155
• Journal Information: Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry, Vol. 121, Issue 27; ISSN 1520-6106
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English