Study On The Solubilization Capacity Of Bio-oil In Diesel By Microemulsion Technology With Rhamnolipid As Surfactant

The development and use of non-petroleum-based renewable fuels have received much attention in recent years due to concerns over current energy shortages and environmental restrictions. Some of the most notable renewable fuels include amongst others: water, solar and wind energy, and biofuels. Biofuel is derived from biomass that can convert to bio-oil by fast pyrolysis or liquefaction. Bio-oil is one option being considered for use as a promising renewable energy source as they have been shown to have some characteristics as combustion fuels used in boiler, engines or gas turbines and resources in chemical industries. But Bio-oils obtained from liquefaction/pyrolysis of biomass have undesired fuel properties, such as high contents of oxygen, low heating values, high water content(15-30 wt %), chemical and thermal instability, low p H values, and poor ignition and combustion properties. Therefore, many bio-oils cannot be accepted commercially and further work such as upgrading is required to be done to im prove the properties of bio-oils. Upgrading bio-oil through emulsification or microemulsification with diesel explores the possibility of replacing the petroleum-based fuels completely.In the study, we put an emphasis on the solubilizing bio-oil in diesel using reverse micellar(water-in-oil or W/O) microemulsions of diesel to produce a blend of bio-oil and diesel for further biofuel application. Synthetic bio-oil was upgraded by solubilizing bio-oil in diesel by microemulsion technology. Diesel microemul sions were formed with rhamnolipid(RL) as surfactant and different kinds of normal alcohols with varying carbon chain length as cosurfactants. Critical micelle concentration(CMC) of the diesel microemulsions was measured by the method of fluorescence probe with Rhoda Mine B as the fluorescent substance. According to the changes in the fluorescence emission intensity, CMC of the diesel microemulsions was measured at 4g/L. The effects of different microemulsion parameters on the solubilization capacity of bio-oil in diesel were investigated, which include initial bio-oil/diesel volume ratio(B/D ratio), surfactant concentration, cosurfactant type, and the mass ratio of cosurfactant/surfactant(C/R ratio). Experimental results indicated that the proper bio-oil/diesel volume ratio was 3:7, the optimal concentration of RL was 15g/L, and the ideal cosurfactant was heptanol with C/R ratio of 2.0. Bio-oil/diesel microemulsion formed under the optimal solubilization conditions was proven to have fuel properties comp arable to diesel.Meanwhile, fuel properties of bio-oil/diesel microemulsion were examined, which include elemental analysis, FT-IR analysis, thermogravimetric analysis, and other common fuel properties. Fuel products indicators include the heating value, density, viscosity, cloud point, pour point, acidity, water content, corrosivity and stability. Compared to the original bio-oil, the bio-oil/diesel microemulsion presented more desirable fuel properties closed to diesel. But it still had some unsatisfactory features, such as acidity.