1,2 Hexanediol as an Alternative Cosurfactant for Preparing Palm-Based Microemulsions for Practical Applications

Abstract

Microemulsions (µE) were prepared with palm fatty acid esters (PFAME) as solvents stabilised by fatty alcohol ethoxylates (hydrophilic-lipophilic balance, HLB value ∼12.8), and 1,2 hexanediol as a co-surfactant. The effects of co-surfactant on the ternary phase systems were studied only at 10, 15, 20, 25, and 30% (w/w) of surfactant concentrations. The ratio of PFAME/water was chosen at 30:70 only. The mixtures were mixed vigorously and then kept at ambient temperature (25°C) for few days. The emulsions (two-phase), µE and liquid crystalline phases were observed using the polarised light. In addition, the physical stability (accelerated test/month at 45°C),conductivity and viscosity for µE solutions were measured. The effects of co-surfactant on the ternary phase systems for PFAME/non-ionic surfactant/water were constructed at 25 and 45°C. The result showed that larger µE region was formed with PFAME 1 than the PFAME 2 at 30:70 ratio of oil to water. The minimum concentration of surfactant for producing clear, low viscosity and thermodynamically stable µE solutions was 10% (w/w) for both PFAME 1 and PFAME 2 at 25°C. However, the concentration of co-surfactant used to produce µE solutions was 12.5% for PFAME 1 but was 30% (w/w) for PFAME 2. Furthermore, the conductivity and viscosity measurements indicated types of µE, that is, O/W or W/O formed.

Keywords:

• Agro and industrial applications
• 1,2 hexanediol
• microemulsions (µE)
• palm fatty acid methyl esters

The author wish to thank the Director General of the Malaysian Palm Oil Board (MPOB) for his approval to publish the manuscript, and to Dr O.T. Lye and Dr H.A. Hassan for their invaluable comments on the article.