Polymeric 1-vinyl-3-ethylimidazolium tetrafluoroborate ionic liquids modified microspheres of silica gel were prepared by free radical polymerization in toluene. Characterization with Fourier transform infrared (FTIR), elemental analysis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), gel permeation chromatography (GPC), thermogravimetric analysis (TGA), and 13C, 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) demonstrated that 1-vinyl-3-ethylimidazolium tetrafluoroborate had successfully loaded on the surface of silica gel and formed a stable polymer coating. Furthermore, to detect the potential desulfurization performance, a series of experiments of model fuel desulfurization with polymeric ionic liquid modified silica gel had been carried out. The desulfurization efficiency of modified silica gel was investigated by removing 2-methylthiophene, benzothiophene, and dibenzothiophene from model fuel (n-heptane/2-methylthiophene, benzothiophene, and dibenzothiophene) under tested conditions. It was shown that the modified silica gel exhibited remarkable desulfurization capacity for aromatic S-containing compounds and the sulfur removal selectivity followed the order of 2-methylthiophene < benzothiophene < dibenzothiophene due to the different density aromatic π-electrons.

SBA-15 functionalized with both zinc ions and ionic liquids was simply synthesized by sol–gel method. The characterization results of Fourier transform infrared spectroscopy, X-ray diffraction, elemental analysis, scanning electron microscopy, energy dispersive spectrometer, atomic absorption spectroscopy, and Brunauer–Emmett–Teller indicated that Zn2+ and imidazolium ionic liquid had been successfully immobilized on SBA-15, imidazolium as cation and [ZnCl3]- /[Zn2Cl5]- as complex anion. The immobilized Zn2+ and ionic liquid did not destroy the typical two-dimensional hexagonal mesoscopic structure of SBA-15 in this experimental research scope. But with the mass of Zn2+ and IL increasing, the mesoscopic order reduced, the pore diameter, pore volume and specific surface area decreased, whereas the wall thickness increased. The adsorption desulfurization experiments showed that the loaded Zn2+ and imidazolium ionic liquid improved the S-removal efficiency of SBA-15 especially for high aromatic sulfur compound.Open image in new window

•[Cn-3-Cnim]Br2 (n = 8, 10, 12) were synthesized and characterized.•[Cn-3-Cnim]Br2 with longer alkyl chain length had lower cmc.•They showed different micellization process within 293.15–313.15 K.•The micropolarity, Nagg of micelles decreased with alkyl chain length increasing.•The aggregation size of [C12-3-C12im]Br2 was distributed in a wide range.A novel class of Gemini imidazolium surfactants 1,3-bis(3-alkylimidazolium-1-yl) propane bromide [Cn-3-Cnim]Br2 (n = 8, 10, 12) were synthesized and characterized by FT-IR, 1H NMR and elemental analysis. The surface activity and aggregation behavior of [Cn-3-Cnim]Br2 (n = 8, 10, 12) were investigated by surface tension, conductivity and steady fluorescence methods. A series of surface active parameters, including cmc, Γmax, pC20, cmc/C20, Amin, γcmc and Πcmc were obtained from surface tension measurement. It was indicated that Gemini imidazolium surfactants with the longer alkyl chain showed the higher surface activity. The thermodynamic parameters of micellization process, namely, standard Gibbs free energy (ΔGmο), enthalpy (ΔHmο) and entropy (ΔSmο) were derived from conductivity measurement at different temperatures. The micropolarity and the mean aggregation number (Nagg) of micelles were evaluated from steady fluorescence spectra. The results revealed that the micropolarity and Nagg of micelles decreased with the increase of hydrocarbon chain length.

Three surfactant-like ionic liquids, 1-dodecyl-3-methylimidazolium tetrafluoroborate (C12mimBF4), 1-tetradecyl-3-methylimidazolium tetrafluoroborate (C14mimBF4), and 1-hexadecyl-3-methylimidazolium tetrafluoroborate (C16mimBF4) had been systematically studied by conductivity measurement, surface tension, steady-state fluorescence measurement and ultraviolet (UV) absorption spectra at 298.15 K. Micellization of the three ILs were certified by the above methods and aggregation number of micelles (Nagg) were determined by pyrene fluorescence quenching method. A comparison of CnmimBF4 with different alkyl chain lengths shows that that the critical micelle concentration (cmc) decreased remarkably with the increase of alkyl chain length, but the surface tensions at cmc (γcmc) were approximately the same, except for that of C16mimBF4. The effects of temperature, inorganic salt, and organic alcohols on the cmc of CnmimBF4 (n = 12, 14, 16) aqueous solution were also investigated. The results showed that the cmc values assumed a trend of increase along with the increase of temperature, and decreased remarkably with the presence of inorganic salt. For alcohol–water systems at lower temperature, the cmc values increased with the presence of short chain alcohols (ethanol, 1-propanol), but decreased or were invariable with long chain alcohols (1-butanol, 1-pentanol). Finally, the micellization thermodynamic parameters (ΔGm°, ΔHm°, ΔSm°) of CnmimBF4 (n = 12, 14, 16) showed that the micelle formation process of C12mimBF4 was entropy-driven, and the micellization behavior of C14mimBF4 and C16mimBF4 was found to be an enthalpy-driven process in the investigated temperature range.