Effect Of Ultrasound And Surfactant On Diesel Oil Micro-emulsification

Emulsification of diesel oil by making micro-water-droplet dispersed in oil is considered as one of the promising techniques to save energy and reduce air pollution. It can be used as an alternative fuel for diesel engines. More and more researchers pay their attention to this technique, since the energy and environment concerning problems become very essential for development of the society and people's life. As the result of the micro-explosions of water droplets in emulsion, diesel oil can be atomized and the contact area of the oil droplets atmosphere increases. Therefore, the effect of the micro-explosions can reduce the imperfect combustion of diesel and its exhaust emission.Ultrasound s one of the new-style means of emulsion. Ultrasonic cavitation is an important effect to assist micro-emulsification. It can reduce emulsifier dosage and change the properties of micro-emulsion, such as reducing the water size of the micro-emulsion to improve the stability of the micro-emulsion.The key to the preparation of diesel-water micro-emulsion is the selection of the emulsifier. Through the experimental ultrasonic emulsification, Cetyltrimethyl Ammonium Bromide (CTAB) was selected as emulsifier and 1-octyl alcohol/1-butyl alcohol as the optimal co-emulsifier were used to prepare the micro-emulsion of water-in-diesel oil. The two techniques of stirrer and ultrasound were compared in this paper. Ultrasound technique is better than stirring, for the average diameter of the water particles in diesel produced by the former was only 30% of that of the latter. The ultrasound effect is studied and a series of ultrasonic parameters are optimized in the research. The optimum ultrasonic condition to get the micro-emulsion was obtained: the ultrasonic frequency 40kHz, the ultrasonic intensity 0.266 W/cm"2, and the treatment time 20min. Then the average diameter of the water particles was 45.3nm in this condition.The representations of the micro-emulsion's stability were studied. The viscosity index method and the high temperature sedimentary time method were used tocompare the stabilities of the micro-emulsion prepared.The built emulsifier prepared with CTAB was studied to reduce the cost of the emulsifier. By the large numbers of experimental test, the built emulsifier Span80/CTAB(3:2)> Span80/CTAB(7:3), Span60/CTAB(l:l)> ABS/CTAB(1:4) were selected to prepare the micro-emulsion of diesel-water. Using the built emulsifier made the dosage of the emulsifier reached 2% of the mass of micro-emulsion. The price of the micro-emulsion diesel oil was estimated to be under 4070 Y/t. The micro-emulsion is transparent and its stable time can keep at least 6 months. The combustion test of the micro-emulsion demonstrated that the micro-emulsion oil could reduce air pollution.