Solubility of water in water-in-oil microemulsions stabilized by cetyltrimethylammonium: Effects of the surfactant counterion, the nature and composition of the oil, and the salinity of the droplets

Journal Article · Tue Jun 01 04:00:00 EDT 1993 · Journal of Colloid and Interface Science; (United States)

DOI:https://doi.org/10.1006/jcis.1993.1237· OSTI ID:6343766

Abuin, E B; Rubio, M A; Lissi, E A ^[1]

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1. Univ. de Santiago de Chile (Chile)

The solubility of water in water-in-oil microemulsions stabilized by cetyltrimethylammonium (CTA) has been investigated as a function of the nature of the surfactant counterion (bromide; CTAB/chloride; CTAC), the composition of the oil (chloroform and chloroform/heptane mixtures), the salinity of the droplets, and the nature of the salt employed to modify it. Changing the composition of the oil from neat chloroform to a 500% mixture with heptane produces an increase of the water solubility in the microemulsions stabilized by CATB and decreases it in the CTAC microemulsions. Strong alterations of the solubility of water were found to occur upon mixing of the surfactants. Solubility increases abruptly on going from either CTAC- or CTAB-stabilized microemulsions to mixtures of both surfactants, reaching a maximum at CTAC mole fractions of 0.5 and 0.4 for solutions of the surfactants in chloroform and chloroform/heptane, respectively. Mixtures of CTAC and CATB in a solvent comprising 500% chloroform/heptane show a different behavior. In this system, water solubility continuously decreases when the CTAC/CTAB ratio increases. Solubility increases with salinity in the CTAC-stabilized microemulsions and decreases in the CTAB-stabilized microemulsions. Nevertheless, the magnitude of the effects observed is dependent on the nature of the salt employed to modify the salinity of the droplets. The results obtained are explained in terms of the model of Shah and coworkers by considering that, due to the stronger binding of bromide than of chloride to the surfactant heads at the micellar interface, water solubility in solutions of CTAB or CTAC in chloroform is determined by different factors: the curvature of the surfactant film (CTAB) and the interaction between droplets (CTAC).

• OSTI ID: 6343766
• Journal Information: Journal of Colloid and Interface Science; (United States), Journal Name: Journal of Colloid and Interface Science; (United States) Vol. 158:1; ISSN 0021-9797; ISSN JCISA5
• Country of Publication: United States
• Language: English

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BROMIDES
BROMINE COMPOUNDS
CHLORIDES
CHLORINATED ALIPHATIC HYDROCARBONS
CHLORINE COMPOUNDS
CHLOROFORM
COLLOIDS
COMPARATIVE EVALUATIONS
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EMULSIONS
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FLUIDS
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HALOGENATED ALIPHATIC HYDROCARBONS
HEPTANE
HYDROCARBONS
HYDROGEN COMPOUNDS
MICROEMULSIONS
MIXTURES
OILS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OTHER ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PERFORMANCE
RESERVOIR ENGINEERING
SALINITY
SOLVENT PROPERTIES
STABILIZATION
SURFACTANTS
WATER