Synthesis of TiO2 Materials Using Ionic Liquids and Its Applications for Sustainable Energy and Environment.

Titanium dioxide (TiO2) has received significant attention because of the global climate change and the consumption of fossil fuel resources. Specifically, using TiO2 in photocatalytic applications, such as the removal of organic pollutants and a hydrogen production has become an important issue. Thus, many researchers have attempted to prepare highly active TiO2 materials using various synthetic approaches. Modifications of the conventional sol-gel method, such as the addition of surfactants, have been employed in synthetic procedures. Moreover, hydrothermal, solvothermal, sonochemical and microwave methods have also been used as alternative approaches. Recently, the use of ionic liquids represents a burgeoning direction in inorganic material synthesis. Ionic liquids are exceptional solvents consisting of ions possessing low vapor pressure and tunable solvent properties. This article reviews the preparation of TiO2 materials using ionic liquids with various synthetic approaches. Also, sustainable energy and environmental cleanup applications of TiO2 materials, including the treatment of hazardous organic substances and hydrogen energy derived from electrochemical methods, are discussed.

Effect of calcination temperature on catalytic activity of Pd/C particle prepared by ionic liquid for hexafluoropropylene hydrogenation.

Palladium particles were simply synthesized using 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6]). The morphology of the particles was significantly affected by the ionic liquid. Palladium was impregnated on a carbon powder for hexafluoropropylene hydrogenation catalysts. Catalytic activity was varied by the calcination temperature. Under the identical conditions, the catalyst prepared using the ionic liquid after calcined at 500 degrees C was the most active in this reaction.

Activity and characterization of mixed organic compounds extracted from Rhodobacter sphaeroides as alternative materials to serum for mammalian cell growth.

Photosynthetic microorganisms produce relatively large amounts of physiologically active materials which stimulate the physiological activity of other organisms. In this study, mammalian HeLa cells were cultured in different culture media which were Dulbecco's modified Eagle medium (DMEM) with newborn calf serum (NCS), and DMEM including different types of physiologically activating compounds (PACs) extracted from Rhodobacter sphaeroides grown under various culture conditions. R. sphaeroides was grown under the following five different culture conditions: anaerobically in the light, anaerobically in the dark and treated with dimethyl sulfoxide, aerobically in the dark for 48 h, in the light for 48 h, and in the light for 24 h and changed after previous culturing in the dark for 24 h. The growth of HeLa cell was measured by cell counting using a hemocytometer, and the fluorescent intensities of cellular lysosomes were measured to check the level of cellular stress caused by adding PACs. The growth of HeLa cells cultured in DMEM with PACs extracted from R. sphaeroides aerobically grown under dark conditions was enhanced compared to that of cells grown with NCS. We also found that a high concentration of pigments such as bacteriochlorophylls and carotenoids and a high concentration of arginine produced by R. sphaeroides aerobically grown in the dark were implicated in increased growth of the HeLa cells. Therefore, our results suggest that PACs extracted from R. sphaeroides aerobically cultured in dark conditions can enhance the physiological activity of mammalian cells and serve as nontoxic and bioavailable materials.

Effect of glucose on xylose utilization in Saccharomyces cerevisiae harboring the xylose reductase gene.

We have constructed recombinant Saccharomyces cerevisiae JH1 harboring a xylose reductase gene (xyl1) isolated from Pichia stipitis. However, JH1 still utilizes glucose more easily than xylose. Therefore, in this study, we characterized the effect of a glucose supplement on xylose utilization, the expression level of xylose reductase as a recombinant gene in JH1, and the expression levels of two hexose transporters (Hxt4 and Hxt7) due to co-fermentation of different concentrations of glucose and xylose. Co-fermentation using 20 g/l of glucose increased xylose consumption up to 11.7 g/l, which was 7.9-fold that of xylose fermentation without a glucose supplement. In addition, we found xyl1 mRNA levels dramatically increased as cells grew under co-fermentation conditions with supplementary glucose; this result is consistent with a significant decrease in the xylose concentration 48 h after cultivation. In addition, the expression levels of Hxt4 and Hxt7 were strongly activated by the presence of glucose and xylose; in particular, Hxt7 showed a 2.9-fold increased expression relative to that of recombinant S. cerevisiae JHM with only a backbone vector, pYES2. The results of this study suggest that xylose utilization would be improved by activation of hexose transporters induced by glucose (rather than xylose) reductase expression.

Preparation of mesostructured barium sulfate with high surface area by dispersion method and its characterization.

The spherical and cubic mesoporous BaSO(4) particles with high surface area were successfully produced via one-step process through precipitation reaction in aqueous solution of Ba(OH)(2) and H(2)SO(4) with ethylene glycol (n-HOCH(2)CH(2)OH) as a modifying agent. The BaSO(4) nanomaterial revealed that the high surface area and the mesoporous was stable up to 400 degrees C. Agglomerate mesoporous barium sulfate nanomaterials were obtained by the reaction of Ba(2+) and SO(2-)(4) with ethylene glycol aqueous solution. The ethylene glycol was used to control the BaSO(4) particle size and to modify the surface property of the particles produced from the precipitation. The dried and calcined mesoporous BaSO(4) nanomaterials were characterized by X-ray diffraction (XRD), BET surface area and N(2) adsorption-desorption isotherm, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared resonance (FTIR) and thermogravimetric analysis (TGA). The as-prepared mesoporous dried BaSO(4) possesses a high BET surface area of 91.56 m(2) g(-1), pore volume of 0.188 cm(3) g(-1) (P/P(0)=0.9849) and pore size of 8.22 nm. The SEM indicates that the morphology of BaSO(4) nanomaterial shows shell like particles up to 400 degrees C, after that there is drastically change in the material due to agglomeration. Synthesis of mesoporous BaSO(4) nanomaterial is of significant importance for both sulphuric acid decomposition and oxidation of methane to methanol.

Effect of Ionic Liquids on Synthesis of Ag/TiO2 Catalyst in Water Electrolysis.

Effective Ag/TiO2 catalyst was synthesized using ionic liquids in water electrolysis. Silver was impregnated on TiO2 particles with various ionic liquids to examine the electrocatalytic activity in acid solution. Among the ionic liquids, [Bmim][CF3SO3] was most effective to prepare Ag/TiO2 particle in cyclic voltammograms. The current density over the sample was higher than 0.02 A/cm2. Furthermore, the catalyst synthesized using TiO2 particle prepared using binary ionic liquid (Ag/TiO2-IL) showed better electocatalytic activity, 0.023 A/cm2, under identical conditions.

Structural Effect of Palladium on Carbon Catalyst for Hexafluoropropylene Hydrogenation.

Palladium was impregnated on carbon particles with various structures using 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF6]) to synthesize a catalyst for hexafluoropropylene hydrogenation. Under the identical reaction conditions (1 bar and 120 °C), the catalyst with mesoporosity (pore size > 500 nm) showed higher than 80% reactant conversion. However, the conversion over the catalyst possessed small pore size was very low. Moreover, the catalyst prepared with ionic liquids was more stable than without ionic liquids.

Growth response of Avena sativa in amino-acids-rich soils converted from phenol-contaminated soils by Corynebacterium glutamicum.

The biodegradation of phenol in laboratory-contaminated soil was investigated using the Gram-positive soil bacterium Corynebacterium glutamicum. This study showed that the phenol degradation caused by C. glutamicum was greatly enhanced by the addition of 1% yeast extract. From the toxicity test using Daphnia magna, the soil did not exhibit any hazardous effects after the phenol was removed using C. glutamicum. Additionally, the treatment of the phenolcontaminated soils with C. glutamicum increased various soil amino acid compositions, such as glycine, threonine, isoleucine, alanine, valine, leucine, tyrosine, and phenylalanine. This phenomenon induced an increase in the seed germination rate and the root elongation of Avena sativa (oat). This probably reflects that increased soil amino acid composition due to C. glutamicum treatment strengthens the plant roots. Therefore, the phenol-contaminated soil was effectively converted through increased soil amino acid composition, and additionally, the phenol in the soil environment was biodegraded by C. glutamicum.