Ostwald ripening of water-in-hydrocarbon emulsions

• Published in: Journal of colloid and interface science Vol. 264; no. 2; pp. 509 - 516
• Main Authors: Jiao, Jim, Burgess, Diane J
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 15.08.2003; Elsevier
• Subjects: Chemistry; Colloidal state and disperse state; Emulsions; Emulsions. Microemulsions. Foams; Exact sciences and technology; General and physical chemistry; Micelle; Ostwald ripening; Particle size; Surfactant Span 83; Micelle; Particle size; Emulsions; Surfactant Span 83; Ostwald ripening; Interface properties; Water oil emulsion; Hydrocarbon; Interface tension; Non ionic surfactant; Kinetic parameter; Polyol
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/S0021-9797(03)00276-5

The purposes of this study are to determine Ostwald ripening rates in water-in-oil (W/O) emulsions and evaluate the potential application of the LSW theory to W/O emulsions. Water-in-oil emulsions were prepared by mixing water and hydrocarbon phases containing Span 83 and homogenizing. n-Heptane, n-decane, n-dodecane, and n-tetradecane were used to obtain a range of solubilities. A linear increase in the cube of the droplet size with time was observed (within the initial period of 1–2 h after emulsion preparation), supporting the LSW theory. Based on this linear relationship, Ostwald ripening rates were determined to be 3.0×10 −24, 2.3×10 −24, 1.8×10 −24, and 5.8×10 −25 m 3 s −1 for water-in-heptane, water-in-decane, water-in-dodecane, and water-in-tetradecane emulsions, respectively. These values are in agreement with theoretical predictions calculated using the LSW equation. It was observed that the ripening process gradually slowed, resulting in deviations from the LSW theory. This was attributed to the effect of the interfacial surfactant film through which the dispersed material has to diffuse during Ostwald ripening. This effect is not taken into consideration by the LSW theory. The results showed that Ostwald ripening of W/O emulsions was less sensitive to the nature of oil used and slower compared to O/W emulsions consisting of the same hydrocarbons.