(232i) Phase Behaviors and Physical Properties of Microemulsion of Palm Oil and Ethanol Emulsified By Low HLB Type of Anionic and Cationic Surfactants

Microemulsion-based biodiesel could be a promising fuel product because of the limitation of petroleum sources in the future. The preparation technique requires less equipment and energy, no chemical reaction involved and catalyze-free. It is related to how to mix vegetable oil, ethanol, surfactant and co-surfactant with proper volumetric ratio to obtain the microemulsion (thermodynamical stability, transparent, and 10-100 nm droplet size) with good physical properties such as, lower kinematic viscosity and lower surface tension regarding to the standard or commercial biodiesel (FAME) prepared by esterification reaction. This work presents a feasibility study of biodiesel development by microemulsion technique using palm oil and ethanol emulsified by low HLB type of anionic surfactant (sodium dioctyl sulfosuccinate, AOT) and cationic surfactant (benzyldimethylhexadecyl ammonium chloride, BMHAC) together with co-surfactants (1-butanol and 1-octanol) at 40 ºC. The ternary phase diagrams reveal that surfactants used in this work could produce w/o and o/w types of microemulsion. The higher surfactant/co-surfactant, the more solubilize between palm oil and ethanol. The AOT/1-octanol mixture shows ability to solubilize palm oil and ethanol at the relatively low composition compared with BMHAC/1-butanol. The experimental results also reveal physical properties regarding to the ASTM standard temperature. For AOT/1-octanol mixture, it can be observed that increasing amount of ethanol results in increasing droplet size and lowering surface tension of microemulsion system due to AOT is more water dispersible (w/o) and surface tension of ethanol is relative low. However, increasing of palm oil results in higher viscosity. For BMHAC/1-butanol mixture, the physical properties show that increasing amount of ethanol results in lowering surface tension and viscosity while increasing amount of palm oil results in larger droplet size due to BMHAC is more oil dispersible (o/w).