- Photocatalytic activity of TiO2 supported SiO2-Al2O3 aerogels prepared from industrial fly ash
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A ternary composite of TiO2 and a SiO2-Al2O3 aerogel with good photocatalytic activity was prepared by a simple sol-gel method with TiO2 nanoparticles and SiO2-Al2O3 aerogels derived from industrial fly ash. The structural features of the TiO2/SiO2-Al2O3 aerogel composite were investigated by X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, gas adsorption measurements and diffuse reflectance UV-visible spectroscopy. The optimal conditions for photocatalytic degradation of 2-sec-butyl-4,6-dinitrophenol (DNBP), included an initial DNBP concentration of 0.167 mmol/L at pH = 4.86 with a catalyst concentration of 6 g/L, under visible light irradiation for 5 h. A plausible mechanism is proposed for the photocatalytic degradation of DNBP. Our composite showed higher photocatalytic activity for DNBP degradation than that of pure TiO2. This indicates that this material can serve as an efficient photocatalyst for degradation of hazardous organic pollutants in wastewater.
- Wang, Hui-Long,Qi, Hui-Ping,Wei, Xiao-Na,Liu, Xiao-Yu,Jiang, Wen-Feng
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- Unusual thermo(photo)chromic properties of some mononitro- and dinitro- substituted 3′-alkyl indolospirobenzopyrans This paper is dedicated to the memory of Dr Thomas G. Nevell.
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Isomeric equilbria of dinitro-substituted indolospirobenzopyrans, possessing 3′-gem-methyl- or 3′-cyclohexyl-substitutents, have been investigated using 1H NMR spectroscopy at six temperatures, ranging from 298 K to 410 K; isomerisation processes in a methanolic solution have been monitored by spectrophotometry. For the mononitro-substituted compounds, equilibrium favoured the colourless spirocyclic isomers. Reversion of the coloured merocyanine isomers, generated by UV irradiation, followed first-order kinetics. For the dinitro-substituted compounds the coloured merocyanine isomers predominated. Following decolourisation by visible light photoirradiation, reversion towards the merocyanine structures were particularly slow, absorbances unusually increasing sigmoidally. UV. spectral observations for the gem-methyl- 1 and 3′-cyclohexyl-substituted systems 2 are qualitatively consistent with the simultaneous involvement of two relatively slow rate determining steps, possessing slowly forming and long-lived intermediates - postulated to be the oxygen protonated pyran-ring of the spirocyclic structure and TCC merocyanine isomer, the latter undergoing relatively slow isomerisation about the central β-alkenic bond to the TTC isomer.
- Abdullah, Ayse,Nevell, Thomas G.,Sammes, Peter G.,Roxburgh, Craig J.
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- Cold microwave chemistry: synthesis using pre-cooled reagents
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A novel experimental procedure for chemical reactions has been devised that involves mixing and then freezing the reagents (organic solvent-free) to a sub-zero temperature such as -30 °C. This frozen mixture is exposed to microwave irradiation for a brief period of time. The use of pre-cooled reagents may give a single product not obtained by traditional microwave irradiation at room temperature. Interestingly, such a product may provide information about mechanisms by identifying the first step of a multiple step reaction.
- Bose, Ajay K.,Ganguly, Subhendu N.,Manhas, Maghar S.,He, William,Speck, Jeffrey
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p. 3213 - 3215
(2007/10/03)
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- Ethylene polymerization by self-immobilized neutral nickel catalysts bearing allyl groups
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[Ni(Ph)(PPh3)(N,O)] complexes containing phenyliminophenolato ligands (N,O) (1: N,O = A; 2: N,O = B; 3: N,O = C; 4: N,O = D; 5: N,O = E) have been synthesized and characterized. The molecular structure of 4 was determined by singlecrystal X-ray analysis. Complexes 2-5 bearing allyl groups have been investigated as self-immobilized catalysts for ethylene polymerization without the use of co-catalysts. The high ethylene polymerization activities of ca. 105 g·PE mol-1 Ni·h-1 and high molecular weight (MW ≈ 105) of polyethylene could be accomplished by changing the ligand structures and reaction conditions. The self-immobilization of catalysts brings about a dramatic increase in the catalytic activities of ethylene polymerization. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Zhang, Dao,Jin, Guo-Xin,Hu, Ning-Hai
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p. 1570 - 1576
(2007/10/03)
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- Method for producing optically active salicylaldimine copper complex
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There is provided a method for producing an optically active salicylaldimine copper complex, which method is characterized in that an optically active amino alcohol compound represented by the following formula (1) is reacted with copper hydroxide (II) in an organic solvent. wherein R1 and R2 which are the same or different, each represent lower alkyl groups and the like which may be substituted, X1 and X2 which are the same or different, each represent a hydrogen atom, lower alkyl groups and the like, and the symbol * designates an asymmetric carbon atom.
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