| A series of Gemini surfactants with different spacer group were synthesized in order to lower the cost of diesel microemulsion. A surfactant with the best emulsification was chosen to apply in diesel microemulsion. The best factors were chosen to prepare the diesel microemulsion by orthogonal test. The microemulsion phase diagrams and evaluation of the application properties of diesel microemulsion were also studied in this paper.The overall results as following:1. Heavy alkylbenzene was used as the raw material. A series of intermediates with different spacer group were prepared and sulfonated with chlorosulfuric acid, and then neutralized with sodium hydroxide and triethanolamine respectively to obtain two series of Gemini surfactants with different spacer groups. The structures of the Gemini surfactants were confirmed by IR and ESI-MS.2. Cmc,γcmc, and C20 of Gemini surfactants were studied. Cmc can reach 10-5 mol·L-1 and shows high surface activity. Forγcmc only, Gemini surfactants didn't show great advantages over monomeric ones. However, they were more efficient in declining surface tension of the water form C20 values.3. The influence of counterion on cmc was studied. Results showed that the surfactants neutralized with triethanolamine have much higer surface activity than with sodium hydroxide. The effect of spacer group on cmc was also studied in this paper. It can be seen that cmc increases unlinely for methylene spacer group, when s was between 1 and 3. And cmc reached the maximum for polyoxyethlene spacer group, when s was 6.4. Diesel microemulsion was prepared with these nine different Gemini surfactants. Through orthogonal test, phase programe, and single factor test, it was determined that the best factors used in diesel microemulsion were Gemini C2, n-butyl aclohol,1% sodium chloride. The diesel microemulsion includes 64.9% diesel, 18.9% water and 16.2% surfactants. It can stabilize for half a year. But the viscosity can't satisfy the requirement from GB 252-77.
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