Influence of Continuous Phase Composition on Physical Properties of Diesel Fuel Emulsions

The objective of this research was to investigate the effects of continuous phase compositions, concentrations of surfactant and water, and duration of ultrasonication on the droplet size, viscosity, density, and stability of diesel fuel emulsions. Fuel emulsions contained kerosene or biodiesel in the continuous phase, and water and an anionic surfactant in the dispersed phase. A central composite in a cube (CCD) response surface experimental design was used for data collection and analysis. Dynamic light scattering analysis of the emulsions showed that the concentrations of surfactant and water and the duration of ultrasonication had significant effects (p < 0.05) on the average droplet size of emulsions containing biodiesel in the continuous phase. Water concentration and water-surfactant interaction had significant effects (p < 0.05) on the average droplet size of emulsions containing kerosene in the oil phase. The average droplet size of emulsions containing biodiesel was smaller than the average droplet size of emulsions containing kerosene; however, the viscosity of the biodiesel emulsions was higher than that of the kerosene emulsions. For both the biodiesel and kerosene diesel fuel emulsions, water-to-surfactant molar ratios of less than 31 produced nanoemulsions that were stable for 30 days of storage at room temperature.