Phase behavior and physicochemical properties of sodium octyl sulfate/n-decane/1-hexanol/aqueous AlCl[sub 3] middle-phase microemulsion

Journal Article · Sun Mar 01 04:00:00 EST 1992 · Langmuir; (United States)

DOI:https://doi.org/10.1021/la00039a017· OSTI ID:5652188

Abe, Masahiko; Yamazaki, Tadao; Ogino, Keizo ^[1]

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1. Science Univ. of Tokyo (Japan)

The phase behavior and physicochemical properties of sodium octyl sulfate/n-decane/1-hexanol/aqueous AlCl[sub 3] middle-phase microemulsion have been studied as a function of salinity to develop an experimental investigation for better understanding of the microstructure of a middle-phase microemulsion. The system exhibits a Winsor-type phase transition (Winsor I [leftrightarrow] Winsor III [leftrightarrow] Winsor II) with increasing salinity. Over an appreciable salinity (from 0.50% to 9.2%), the formation of Winsor III, composed of a middle-phase microemulsion in equilibrium with the excess water and oil phases, was observed. It has been observed that as the salinity is increased, the phase volume of the middle-phase microemulsion undergoes a drastic decrease at a specific brine concentration (3.8%). Furthermore, the physicochemical properties such as water content, electrical conductivity, diffusion coefficient, and solubilization of 1-hexanol in the AlCl[sub 3] middle-phase microemulsion all show abrupt changes at this salinity. The drastic change in the phase volume and physicochemical properties at the specific salinity of 3.8% may be attributed to a phase inversion of the AlCl[sub 3] middle-phase microemulsion from oil-rich to water-rich continuous phase with increasing AlCl[sub 3] concentration, which is quite a different behavior from that observed for monovalent and divalent salt systems. Specifically, it may be assumed that a fluctuating structure of bicontinuous type and a liquid crystal structure overcome the droplet structure in the phase equilibrium at a certain salinity during the increase in the trivalent salt concentration. 25 refs., 10 figs.

• OSTI ID: 5652188
• Journal Information: Langmuir; (United States), Journal Name: Langmuir; (United States) Vol. 8:3; ISSN LANGD5; ISSN 0743-7463
• Country of Publication: United States
• Language: English

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CHEMISTRY
COLLOIDS
DISPERSIONS
EMULSIONS
ENHANCED RECOVERY
MICROEMULSIONS
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