Use of Span 80 and Tween 80 for blending gasoline and alcohol in spark ignition engines

Span 80 and Tween 80 are biodegradable surfactants that can be added to blended fuels such as hydrated bioethanol-gasoline and methanol-gasoline. They increase the fuels' water tolerance and reduce their corrosive properties, without altering their fuel characteristics. For this study, a mixture of surfactants Span 80 and Tween 80 was added to create an emulsion and the optimum hydrophilic:lipophilic balance (HLB) was determined. The effect of this additive mixture on spark ignition (SI) engines and the resulting gas emissions were also investigated. Four kinds of fuel mixtures were tested in this study. They were: 10% denatured (DN) ethanol mixed with 90% commercial unleaded gasoline 92 (E10); a blend of 63% commercial unleaded gasoline 92, 17% straight-run naphtha and 20% DN ethanol (E20); 75% commercial unleaded gasoline 80 and 25% DN ethanol (E25); and 9% methanol with 91% commercial unleaded gasoline 92 (M9). The four product blends were compliant with the international standards EN-228 and ASTM-D4814. They also produced good engine performance and reduced amounts of carbon monoxide (CO) and nitrogen oxide (NOx) emissions compared with standard fuels.