Comparison of Fuel Properties of Nanoemulsions of Diesel Fuel Dispersed with Solketal by Microwave Irradiation and Mechanical Homogenization Methods

Solketal chemically derived from bioglycerol was shown in this study to improve the fuel characteristics of ultralow sulfur diesel. Either microwave irradiation or mechanical homogenization method was applied to prepare the nano- or microemulsions of solketal-in-ultralow sulfur diesel. A nonionic surfactant mixture was used to reduce the surface tension of the interphase among the components to facilitate emulsion formation. The fuel properties of those emulsions were analyzed and compared. The experimental results show that a weight fraction of solketal lower than 5 wt % along with a surfactant mixture amounting to 15 wt % would produce a nanoemulsion that contains a mean droplet size of the dispersed phase in the range of nanometers. The nanoemulsion with 3 wt % solketal as a combustion improver for diesel fuel, prepared by a microwave-irradiating reactor, appeared to have the highest amount of heat release, combustion efficiency, and the lowest carbon residue due to the increase in the combustion efficiency and was thus considered to be the optimum composition for acquisition of superior fuel properties. In addition, the nano- and microemulsions formed by the mechanical homogenizer had a lower cold filter plugging point and a higher flash point. Higher solketal content in the emulsions caused an increase in the dispersed droplet size and reductions in the amount of heat release, carbon residue, the flash point, and the cold filter plugging point.