Effect of diols as co-surfactants in partial ternary phase behaviour of palm oil-based Microemulsions

Microemulsions (μe) were prepared with palm fatty acid methyl esters (pfame) as solvents,and stabilised by ethoxylated non-ionic surfactants,i.e.,dehydol ls 7 and dehydol ls 2 as sa and sb with the hydrophiliclipophilic balance (hlb) values at ∼12.8 and ∼7.3,respectively. the co-surfactants chosen were 1,2-hexanediol,1,2-butanediol,1,2-ethanediol and glycerol. the effects of the co-surfactants on the partial ternary phase diagrams were studied at 10%,15%,20%,25%,30% and 40% (w/w) concentrations. the ratio of pfame to water was either 25:75 or 50:50. the mixtures were agitated vigorously,and then kept at ambient temperature (25°c) for one to two days. the emulsions (two-phase),the μe and liquid crystalline phases were observed using polarised light. in addition,the physical stability of the μe solutions was determined at 45°c over a period of one month. the effects of the co-surfactants on the ternary phase systems for pfame/non-ionic surfactants/water were studied and mapped out at 25°c and 45°c,respectively.