Preparation of finely dispersed O/W emulsion from fatty acid solubilized in subcritical water

Pramote Khuwijitjaru, Yukitaka Kimura, Ryuichi Matsuno, Shuji Adachi

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


A novel method for preparing a finely dispersed oil-in-water emulsion is proposed. Octanoic acid dissolved in water at a high temperature of 220 or 230°C at 15 MPa was combined with an aqueous solution of a surfactant and then the mixture was cooled. When a nonionic surfactant, decaglycerol monolaurate (ML-750) or polyoxyethylene sorbitan monolaurate (Tween 20), was used, fine emulsions with a median oil droplet diameter of 100 nm or less were successfully prepared at ML-750 and Tween 20 concentrations of 0.083% (w/v) and 0.042%, respectively, or higher. The diameters were much smaller than those of oil droplets prepared by the conventional homogenization method using a rotor/stator homogenizer. However, an anionic surfactant, sodium dodecyl sulfate, was not adequate for the preparation of such fine emulsions by the proposed method. Although the interfacial tensions between octanoic acid and the surfactant solutions were measured at different temperatures, they were not an indication for selecting a surfactant for the successful preparation of the fine emulsion by the proposed method.

Original languageEnglish
Pages (from-to)192-197
Number of pages6
JournalJournal of Colloid And Interface Science
Issue number1
Publication statusPublished - Oct 1 2004
Externally publishedYes


  • Droplet size
  • Interfacial tension
  • Octanoic acid
  • Oil-in-water emulsion
  • Subcritical water

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry


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