Analysis of compositions and fuel specifications of the aqueous emulsion fuels of gasoline (RON 90)-ethanol-water in stable emulsions at low temperatures

Many countries worldwide encounter the greatest difficulties in improving people's life quality since fossil fuel reserves are decreasing, causing fuel prices to rise drastically. This problem has made many countries, including Indonesia, struggle to import them from producers in the Middle East. Adding a small part of ethanol to gasoline is one of the solutions that has been investigated and developed. The previous works relating to blended fuels, gasoline and ethanol, generally employed absolute alcohol, which was expensive. A small surfactant was added to the mixture to stabilize the emulsion, and the blending was conducted in normal conditions (room temperature). If the composition of gasoline and aqueous ethanol is not precise, the components can be separated at a specific temperature. The present study is aimed to report the analysis of compositions and fuel specifications of aqueous emulsions of gasoline (RON 90)-ethanol-water in a single phase without using a synthetic surfactant in the temperature range of 0–25 °C. The procedures were as follows: fermentation, ethanol distillation and purification, cooling, blending, and characterization of fuel specifications. Components of gasoline (RON 90)-ethanol-water formed a stable emulsion in the composition range of 28.00‒99.79 %, 0.20‒67.97 %, and 0.01‒3.58 %. The observation found that continually increasing the amount of aqueous ethanol and temperature after one phase was attained would not lead to the separation of components. Therefore, gasoline and aqueous ethanol can form a single phase functioning as a surfactant binding water and fossil fuel. The decrease in temperature after the emulsion is stabilized can separate the components whereby it is caused by the faster density change of aqueous ethanol than gasoline