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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 ([C 12 -2-im][2Ac]) and 1,5-bis[N-(N ´ -dodecyl imidazole)]pentane diacetate ([C 12 -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 ([C 12 -5-im][2Ac]) has exhibited better performance than [C 12 -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 [C 12 -2-im][2Ac] and [C 12 -5-im][2Ac]. [Display omitted] • Ionic liquids type Gemini surfactants (ILGS) of varying spacer lengths are prepared. • Gasoil/sunflower oil microemulsions usable in diesel engines are prepared using ILGS. • ILGS structure can be designed to tune their emulsification performance. • ILGS based fuel microemulsions were stable for upto 6 months on the shelf. • Physicochemical properties of prepared fuel microemulsion were in the optimum range. [ABSTRACT FROM AUTHOR]

The formulation of an economical diesel/colza oil/water microemulsion fuel is reported. The modification of diesel fuel significantly improves its fuel properties as well as environmental pollution issues. To investigate the possibility of using colza oil with diesel fuel and adding water to reduce emissions of diesel combustion, the phase diagrams of the system were constructed using titration method with co‐surfactant. n‐Butanol is selected as co‐surfactant among the investigated alcohols with different chain lengths as it formed wide single phase area. Using of n‐butanol was helped to tune solubilizing of water in diesel/colza oil blend and to reduce its viscosity. Here, a 4:1 blend of diesel:colza oil, 5% water and n‐butanol was selected as base system which was then optimized to obtain a reasonably economical formulation with acceptable physical properties. According to the measurements of physical properties, such as viscosity, temperature stability, water droplet size and considering an economical point of view, the optimum microemulsion system was composed of 75% diesel/colza oil (4:1), 5% water, 10% n‐butanol, 8% Brij 30 and 2% Tween 80, and was prepared in room temperature (21–25) °C by stirring with 500 rpm for 5 min. The optimum system was stable up to 45°C. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1762–1769, 2018 [ABSTRACT FROM AUTHOR]

In recent decades, using of vegetable oils has gained major attention as an alternative and renewable fuel source. But, the high viscosity of vegetable oils makes them to be problematic for the fuel engines in long-term use. Blending of vegetable oils with diesel as modified diesel fuel has been considered as the most common method for reducing the negative effects of vegetable oils, such as high viscosity. The main purpose of this research is to study the phase behavior of new w/o microemulsion systems with focus on formulating an optimized fuel system. The effects of several parameters such as surfactant, co-surfactant, blends of several surfactants (HLB), temperature, stirring speed and stirring time on the physical properties of the studied systems, such as viscosity, water droplet sizes were examined. The optimum system formulated here was composed of diesel/colza oil blend (80:20 wt%) 44 wt%, Span 80 as surfactant 4 wt%, 1-butanol as co-surfactant 47 wt% and 5 wt% water. The size of water droplets in the formulated optimum system has been about 4.6 nm and the system showed no phase separation for up to 9 months on the shelf. [ABSTRACT FROM AUTHOR]

The fuel microemulsions of water in a 4:1 (v:v) blend of gasoil and sunflower oil (respectively) by using of 1-dodecyl-3-methylimidazolium nitrate ([C12mim][NO 3) and 1-butyl-3-methyl imidazolium nitrate ([Bmim][NO 3) ionic liquids as surfactant and 1-butanol as co-surfactant. Also, the performance of 50:50 wt% blend of the mentioned ionic liquids with Span 80 as surfactant was evaluated in this work. The comparison of the phase diagrams of the samples has revealed a larger single phase region for samples prepared with ionic liquids than the conventional Span 80 surfactant or their blends with Span 80. The dynamic viscosity, and density of two samples with high oily phase content was measured according to the standards showing very close values to the net diesel fuel. DLS analysis indicated a water droplets of 9 nm (up to 70%) for [Bmim][NO 3 , 3–6 nm (up to 64–82%) for [C12mim][NO 3 , and 331 nm (up to 53%) for systems prepared by Span 80. Meanwhile, a very narrow size distribution was observed for the samples prepared by ionic liquids. No phase separation has been observed for the prepared samples over 6 months on the shelf. • Methylimidazolium based ionic liquids is used as surfactant in emulsifying of water in diesel/sunflower oil blend. • The prepared microemulsions has been stable for 9 months on the shelf. • The ionic liquids exhibited performances comparable to the commercial surfactants such as Span 80. [ABSTRACT FROM AUTHOR]