Junchun Li

Microemulsions with ionic liquid polar domains

In this work 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4], an ionic liquid)/Triton X-100 (TX-100)/cyclohexane microemulsions have been prepared and characterized by phase behavior, conductivity measurement, dynamic light scattering, freeze-fracturing electron microscopy, and UV-vis techniques, and our attention is concentrated on the microemulsions with the ionic liquid as the nano-sized polar domains.

Preparation of room-temperature ionic liquids by neutralization of 1,1,3,3-tetramethylguanidine with acids and their use as media for mannich reaction

Abstract New room‐temperature ionic liquids (ILs) were prepared by neutralization of 1,1,3,3‐tetramethylguanidine with different acids under ambient condition. The density, viscosity, decomposition temperature, electronic conductivity, and miscibility with some commonly used solvents were determined. As an example of the applications of the new ILs, the reaction of benzaldehyde, aniline, and acetophenone was carried out in the ILs. The ILs are easily prepared in large scale.

Compressed CO2-enhanced solubilization of 1-butyl-3-methylimidazolium tetrafluoroborate in reverse micelles of Triton X-100

We carried out the first study about the effect of a compressed gas on the properties of reverse micellar solutions with ionic liquid (IL) polar cores. And the properties of compressed CO2/cyclohexane/1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4])/Triton X-100 (TX-100) system were investigated at 288.2, 293.2, 298.2, 308.2 K and different pressures by using phase behavior measurement, small-angle x-ray scattering, and UV-Vis techniques. The concentration of the surfactant in the solution was 0.3 mol/l (M). It was found that compressed CO2 could enhance solubilization of the IL in the reverse micelles considerably at suitable pressures, and formation of the reverse micelles could be controlled easily by pressure. Increase of CO2 pressure resulted in decrease of the micellar sizes at fixed [bmim][BF4]-to-surfactant molar ratios (w), and the size of the reverse micelles increased with the increase of w values. The polarity of the IL cores increased continuously with increasing w value.

Mimic oil recovery with a SDBS–dodecane–silica gel system

Abstract The wettability of the solid powder of silica gel was determined via a modified Washburn equation expressed as contact angles. The interfacial tension ( γ ) between the dodecane and the dilute sodium dodecyl benzene sulfonate (SDBS) aqueous solution was obtained using the spinning drop ( γ −1 ) or drop volume methods ( γ >10 mN m −1 ). Contact angle changes for SDBS aqueous solutions on the surface of a silica gel powder were studied. The average aggregation number of SDBS micelles in aqueous solution was determined using the fluorescence quenching method. The relationship between the wettability of the powder surface, the critical micelle concentration (CMC) of SDBS and the mimic oil recovery of the resident oil on the powder surface has been explored. It has been found that good residual oil recovery was achieved by surface wettability changes at the interfacial tensions around 4–5 mN m −1 , which is far from the ‘ultra low’ condition (≤10 −3 mN m −1 ).

Effect of compressed CO2 on the chloroperoxidase catalyzed halogenation of 1,3-dihydroxybenzene in reverse micelles

The effect of compressed CO2 on the specific activity of chloroperoxidase (CPO) to catalyze the chlorination of 1,3-dihydroxybenzene in cetyltrimethylammonium chloride (CTAC)/H2O/octane/pentanol reverse micellar solution was studied. The results show that the specific activity of the enzyme can be enhanced significantly by compressed CO2, and the specific activity can be tuned continuously by changing pressure. The mechanism for the specific activity enhancement of the enzyme by CO2 was also studied. We believe that compressed CO2 can be utilized to tune some other enzyme catalytic reactions in different reverse micellar systems with potential advantages.