Upgrading Bio-oil through Emulsification with Biodiesel: Thermal Stability

Storage properties and thermal stability of fuels are important background information when dealing with a new potential fuel. Following the first paper on the preparation and characterization of the fuel mixture produced through emulsification of bio-oil and biodiesel, the second part of this investigation reports on the storage and thermal stability of the bio-oil/biodiesel mixture. The physicochemical properties of the samples stored at different temperatures (60 and 80 degrees C) for up to 180 h are measured. Fuel properties, such as viscosity, water content, acid number, and average molecular weight of the bio-oil/biodiesel mixture, are measured before and after aging. In contrast to the aging properties of bio-oil alone, very little changes in water content and viscosity are shown for the mixtures aged at 80 degrees C for 180 h. Overall, a slight decrease in acid numbers is observed for the aged mixtures. Chemical changes are characterized using gel permeation chromatography (GPC), showing a slight increase in the molecular weight over time, possibly because of some polymerization and condensation reactions during storage. Further confirmation of the changes is shown through a Fourier transform infrared spectrometer (FTIR), thermal decomposition analysis using a thermogravimetric analyzer (TGA), and proton assignment using proton nuclear magnetic residence (H-1 NM R) spectroscopy. Finally, the study indicates that the bio-oil/biodiesel mixture is stable within the conditions tested as a fuel.