Phase behavior of AOT microemulsions in compressible liquids. [AOT = bis(2-ethylhexyl) sodium sulfosuccinate]

Journal Article · Thu Jun 13 00:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100165a052· OSTI ID:5990918

McFann, G J; Johnston, K P ^[1]

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1. Univ. of Texas, Austin (United States)

The phase behavior of bis(2-ethylhexyl) sodium sulfosuccinate (AOT)-alkane-brine systems is described over a wide range of pressure, temperature, and salinity for alkanes from ethane to dodecane. The partitioning of AOT between the oil, middle, and brine phases is reported for propane in order to determine the natural curvature. This is important for understanding separation processes with water-in-oil microemulsions. For the lighter, more compressible alkanes, the pressure effect on the hydrophilicity of the surfactant is much larger and in the opposite direction as for the heavier, less compressible ones. In propane at constant temperature and salinity, water-in-oil (w/o) microemulsions have been converted to middle phase microemulsions and then to oil-in-water (o/w) microemulsions by decreasing the pressure. These phase inversions are described in terms of the immiscibilities in the binary systems, and the molecular interactions at the surfactant interface. Although temperature and salinity are used commonly to manipulate interactions primarily on the water side of the interface, these results show it is possible to control interactions on the oil side by adjusting the pressure. The well-established trends in the phase behavior and size of microemulsion drops for dodecane through hexane are not observed for the lighter alkanes. For butane through ethane, a new unusual behavior is identified and attributed to a significant decrease in the strength of the attractive interactions between the surfactant tails and the alkane.

• OSTI ID: 5990918
• Journal Information: Journal of Physical Chemistry; (United States), Vol. 95:12; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
MICROEMULSIONS
PHASE STUDIES
ALKANES
BRINES
EXPERIMENTAL DATA
HIGH PRESSURE
MEDIUM PRESSURE
ORGANIC OXYGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PARTITION
PRESSURE DEPENDENCE
SURFACTANTS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
COLLOIDS
DATA
DISPERSIONS
EMULSIONS
HYDROCARBONS
INFORMATION
NUMERICAL DATA
ORGANIC COMPOUNDS
TEMPERATURE RANGE
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