Ionic Liquid Modification Research Articles

Room temperature ionic liquid (RTIL)-decorated mesoporous silica SBA-15 for papain immobilization: RTIL increased the amount and activity of immobilized enzyme

Mesoporous materials, especially functionalized ones, have become a promising carrier for enzyme immobilization. We synthesized room temperature ionic liquid-decorated mesoporous SBA-15 (RTIL-SBA-15) for papain immobilization. The results of powder XRD, IR and N 2 adsorption–desorption isotherms have confirmed that ionic liquid [Simim +][Cl −] was successfully grafted on the surface of SBA-15. As a consequence of the electrostatic attraction between the cation [Simim +] and the negatively charged papain, RTIL-SBA-15 had an advantage over SBA-15 when papain was immobilized at pH = 9.00. The kinetic study showed that the interaction between papain and the carrier was stronger after ionic liquid modification. In the casein hydrolysis, the papain immobilized on RTIL-SBA-15 showed a higher specific activity than that on SBA-15, implying that the ionic liquid [Simim +][Cl −] was beneficial to improve the activity of the immobilized papain. The optimum pH of the immobilized papain was shifted to higher than that of free enzyme.

Visible Light Photocatalysis of BiOI and Its Photocatalytic Activity Enhancement by in Situ Ionic Liquid Modification

In this study, we investigate the photocatalysis mechanism of BiOI in detail and therefore demonstrate that the photocatalytic activity of BiOI could be enhanced greatly by in situ modification of an ionic liquid [Bmim]I (1-buty-3-methylimidazolium iodide). The ionic liquid modified BiOI (IL-BiOI) was prepared by reacting bismuth nitrate with [Bmim]I in water at 70 °C, where the ionic liquid could act as both iodine source and surface modified agent. On degradation of methyl orange (MO) under visible light irradiation (λ > 420 nm), IL-BiOI photocatalyst exhibited superior photocatalytic activity to the unmodified counterpart synthesized in the absence of [Bmim]I. The effects of ionic liquid modification on the photocatalytic activity enhancement were systematically investigated. We found that IL modification could trap the photoexcited electron at conduction band of BiOI to inhibit the recombination of photoinduced electron–hole pairs and thus enhance its photocatalytic activity on the degradation of orga...

The use of silica nanoparticles for gas chromatographic separation

A new IL-dispersed silica nanoparticles (IL-SNs) capillary column, combining properties of silica nanoparticles and ionic liquid (IL), was used for gas chromatographic separation. By dispersing silica nanoparticles in a conventional IL of 1-butyl-3-methylimidazolium hexafluorophosphate ([BuMIm][BF6]), a layer of homogeneous interconnected particulate silica networks (thickness: 0.4–0.6 μm) was formed on the inner surface of a capillary column. This coating integrates advantages of silica nanoparticles (high surface area, high dispersed behaviour) and IL (extended liquid-state temperature range, chemical stability), hence increasing interactions between stationary phase and analytes. It was demonstrated that mixtures of a wide range of organic compounds including alcohols, esters, alkanes, aromatic compounds, as well as isomers and non-polar compounds can be well separated using an IL-SNs capillary column. Comparing to traditional support coated open tubular columns, the IL-SNs capillary column displays retention behaviors of separating both polar and non-polar compounds. The much thinner coating film of IL-SNs capillary column, compared to the coating film of SNs capillary column, decreases the resistance to mass transfer, resulting a good column efficiency of 3030 theoretical plates per meter for n-butanol (which is about 5 times higher than for the SNs capillary column). Furthermore, the IL-SNs capillary column decreases the IL retention selectivity dominated by IL structures, and has a higher coating value than neat IL stationary phase. Moreover, the preparation is simple as no modification of ILs or adoption of additional reagents is needed in pretreatments. This manuscript is the first report on the use of silica nanoparticles for gas chromatography, which would expand the applicability of silica nanoparticles in analytical chemistry.

Enhancing Dye Adsorption of Wool Fibers with 1-butyl-3-methylimidazolium Chloride Ionic Liquid Processing

In this paper, 1-butyl-3-methylimidazolium chloride ionic liquid (IL) which has good solubility for wool keratin, was employed to treat the wool fibers. The characterization of IL treatment on the wool fibers was first investigated using scanning electron microscopy (SEM), the Allwörden reaction and X-ray diffraction (XRD) analysis. Then, the effect of the IL treatment on the wool adsorption properties for an acid dye was studied through the dyeing rate test. The IL treatment was proven to be an effective process for wool characterization. The scales of the IL-treated wool fibers were eroded and even dislodged when the treatment temperature was increased according to the SEM observations. The Allwörden reaction showed that the epicuticle of wool fibers was damaged and became incomplete after the IL treatment. XRD indicated that the IL treatments could cause the decrease in the degree of crystallinity of wool fibers. Furthermore, the adsorption and diffusion behaviors of the IL-treated wool samples showed that the ionic liquid modification could improve the sorption properties of the wool fibers as represented by the increases in the dyeing rate.

Ionic Liquid Modification of Layered Silicates for Enhanced Thermal Stability

AbstractA natural and synthetic layered silicate (LS) was modified with trihexyltetradecyl‐phosphonium tetrafluoroborate (an ionic liquid) via a cationic exchange reacation. The exchange reaction and loading of modifier was investigated using a combination of WAXD, inductively coupled plasma‐optical emmission spectroscopy (ICP‐OES) and thermogravimetric analysis (TGA). The thermal stability of the modified LS was enhanced by up to 150 °C, when compared with conventional quaternary ammonium cations, making melt mixing of such modified nanoclays possible with poly(ethylene‐terephthalate) (PET).magnified image

Liquid-Crystalline Formation and Functionalization of Ionic Liquids through Self-Organization Processes

Self-assembly of liquid-crystalline molecules that combine order and fluidity is one of promising approaches to the preparation of nanostructured functional materials. Here we present a development of liquid-crystalline materials exhibiting anisotropic ionic conductivities by self-organization of ionic liquids. A new class of liquid-crystalline materials with layered (smectic) and cylindrical (columnar) structures was prepared by supramolecular association of conventional ionic liquids and hydrogen-bonded mesogenic molecules and by the chemical modification of ionic liquids. These materials formed nano-segregated structures consisting of ion-conducting and insulating parts in the liquid-crystalline states. Anisotropic ionic conductivities were induced by the formation of a single domain in the liquid-crystalline phases and the macroscopic alignment of the ion-conductive paths. Free-standing ion-conductive polymer films were also prepared by fixation of aligned structures of polymerizable liquid-crystalline ionic liquids through photoirradiation.