Gasoil/sunflower oil blend/water fuel microemulsions prepared with ionic liquids-type Gemini surfactants

Abstract

Finding more efficient surfactants for water emulsification in diesel or its blends with vegetable oil biodiesels, to resolve their environmental and technical issues is an important research field. Ionic liquid-type Gemini surfactants (ILGS), 1,2-bis[N-(N ´ -dodecyl imidazole)]ethane diacetate ([C12-2-im][2Ac]) and 1,5-bis[N-(N ´ -dodecyl imidazole)]pentane diacetate ([C12-5-im][2Ac]) are synthesized and evaluated for formulation of gasoil/sunflower oil (80:20) fuel microemulsions. ILGS have two connected head-groups on each molecule, a tunable chemical structure and emulsification performance, and it was expected that their structure can be designed to form highly stable micelles. The performance of Tween80, Span80 and ILGS were compared in formulation of a single-phase fuel microemulsions via titration with 1-butanol as cosurfactant. ILGS with longer spacer length ([C12-5-im][2Ac]) has exhibited better performance than [C12-2-im][2Ac] with shorter spacer length resulting to lower 1-butanol consumption, which is attributed to the formation of more stable micelles. The 70:27:3 mixture of Tween80:Span80:ILGS has been determined as optimum surfactant mixture resulting in samples which have been remained stable as a single phase for upto 6 months. A narrowly distributed DLS hydrodynamic water droplets size of 8 and 4 nm, and a kinematic viscosity of 6.4434 and 6.6055 mm2/s (comparable to diesel) were measured for samples prepared by [C12-2-im][2Ac] and [C12-5-im][2Ac].

Keywords

• Diesel fuels
• Diesel engines
• Microemulsions
• Ionic liquids
• Gemini surfactants
• Ternary phase diagram