Microemulsion based hybrid biofuels from Thevetia peruviana seed oil: Structural and dynamic investigations

Abstract

Abstract The structure and dynamics of microemulsion based hybrid biofuels (MHBFs) from Thevetia peruviana seed oil (TPO) were investigated for the first time in this study. Nonionic surfactants like fatty esters (FAME), oleyl alcohol (OA) and ethylene glycol butyl ether (EGBE) were introduced into the system to investigate their influence on MHBF characteristics. Introduction of these surfactants resulted in modification of structure and dynamics of simple systems comprising of vegetable oil, butan-2-ol and ethanol. The diffusion co-efficient increased from 0.13 × 10 −11 to 5.10 × 10 −11 m 2 /s, which indicated the formation of reverse micellar system. Besides, decrease in the rate of droplet coalescence from 10 −1 to 10 −5 times the collision factor signified the increase in physical stability of MHBFs. The number of droplets increased from 1.88 × 10 18 to 6.60 × 10 22 and average length of surface active agent decreased from 8.8 to 0.26 nm. The introduction of OA and FAME also increased the gross calorific value (GCV) (from 38.91 to 40.21 MJ/kg). Moreover, the introduction of EGBE resulted in decrease in pour points of MHBFs from 1 °C to −8 °C. Conclusively, the conversion of fatty acids to corresponding esters (FAMEs), introduction of long chain alcohol (like OA) and anti freezing agent (EGBE) contributed towards improvement in fuel quality of simple MHBF.