Emulsified fuels based on fatty acid distillates and rapeseed oil: A physicochemical characterization

The emulsification of water in vegetable oils is one of the most promising techniques reported in order to reach an engine-friendly fuel with proper physicochemical properties, allowing improvements in the atomization process and exhaust emissions. For this reason, the scope of this investigation is to formulate and characterize emulsified fuels using different continuous phases, as well as to analyze the influence of the increase of the surfactant concentration on the system stability. The emulsified systems were formulated using ultrasonic equipment and consisted of continuous phase rapeseed oil and fatty acid distillates mixed with diesel fuel. Additional components such as deionized water, ethanol and octanol, as well as sorbitan monooleate and polyoxyethylene sorbitan monooleate as surfactant, were used. The formulated dispersed systems were covered under different experimental factors and summarized in ternary diagrams. Several stable dispersed systems were achieved (emulsions and microemulsions); but only with the introduction of diesel fuel to the formulations, proper viscosity values were achieved. An increase of the viscosity with increasing the amount of water was noted. The water droplets sizes of emulsified rapeseed oil were smaller than in the emulsified fatty acid distillates. Finally, an increase of surfactant percentage in the emulsification process improved the dispersed systems' stability and their optical appearance, whereas also slight differences in density, viscosity and surface tension values were noted.