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The excited triplet state of 1-nitronaphthalene, 1NN, (31NN) is able to oxidise nitrite to NO2, with a second-order rate constant that varies from (3.56 ± 0.11) × 108M−1s−1(μ ± σ) at pH 2.0 to (3.36 ± 0.28) × 109M−1s−1at pH 6.5. The polychromatic quantum yield of NO2photogeneration by 1NN in neutral solution is ΦNO21NN≥ (5.7 ± 1.5) × 107× [NO2−]/{(3.4 ± 0.3) × 109× [NO2−] + 6.0 × 105} in the wavelength interval of 300–440 nm. Irradiated 1NN is also able to produce OH, with a polychromatic quantum yield ΦOH1NN= (3.42 ± 0.42) × 10−4. In the presence of 1NN and NO2−/HNO2under irradiation, excited 1NN (probably its triplet state) would react with NO2to yield two dinitronaphthalene isomers, 15DNN and 18DNN. The photonitration of 1NN is maximum around pH 3.5. At higher pH the formation rate of NO2by photolysis of NO2−/HNO2would be lower, because the photolysis of nitrite is less efficient than that of HNO2. At lower pH, the reaction between 31NN and NO2is probably replaced by other processes (involving e.g.31NN-H+) that do not yield the dinitronaphthalenes. [ABSTRACT FROM AUTHOR]

The influence of different magnesium (Mg) weight percentages (1, 2.5, 5, 7.5 and 10) over silver (3 wt%) impregnated alumina (SA) catalyst was investigated for the reduction of NO by C3H6. Mg doped SA catalysts were prepared by conventional impregnation method and characterized by XRD, BET-SA, ICP-MS, XPS, SEM, UV-DRS, H2-TPR and O2-TPD. The existence of MgO and MgAl2O4 phases on Mg doped SA catalysts were observed from XRD and XPS analyses. Existence of high percentage MgAl2O4 phase on 5% Mg doped SA catalyst (Mg (5) SA) enhances the dispersion and stabilization of silver phases (Ag2O). Mg (5) SA catalyst shows a 51% of high selectivity (NO to N2) in presence of SO2 (80 ppm) at low temperatures (350 °C) and maintained high selectivity’s with a wide temperature window (350–500 °C). An optimal high surface availability of Ag0 and Ag+ species were observed from XPS analysis over Mg (5) SA catalyst. H2-TPR analysis shows high temperature reduction peak over Mg (5) SA compared to SA catalyst. XPS analysis confirms the high percent availability of MgAl2O4 species over Mg (5) SA catalyst. DRIFTS study reveals the molecular evidences for the evolution of enolic species during NO reduction over the highly active Mg (5) SA catalyst at low temperatures. It also confirms further transformation of enolic species into –NCO species with NO + O2 and finally into N2 and CO2. [ABSTRACT FROM AUTHOR]

Photocatalytic bactericidal activity of TiO2, and supported over HY, Hβ, HZSM-5 and SiO2–Al2O3 systems were investigated by taking Escherichia coli as a water pathogenic bacterial pollutant indicator. TiO2 of 0.75 g/L was the optimum concentration for higher bactericidal activity. Among HY, Hβ, HZSM-5 and SiO2–Al2O3 supports, Hβ supported system showed highest bacterial adsorption. This may be due to high surface area of Hβ compared to others and its hydrophobic nature of zeolite that attracts the organic bacterial pollutants than the binary SiO2–Al2O3. Different loading of TiO2, ranging from 2 to 15 wt.% supported on Hβ zeolite samples are evaluated for dark adsorption measurements and photocatalytic bactericidal activity studies. Increasing the TiO2 percentages onto zeolite support resulted decrease of bacterial adsorption. It is observed that 5 wt.% of TiO2/Hβ system exhibited high photocatalytic bactericidal activity compared to other catalysts. This higher bactericidal activity over 5 wt.% of TiO2/Hβ in comparison with TiO2 alone is due to the greater adsorption of bacteria and optimum dispersion of TiO2 on Hβ zeolite facilitating higher OH• radical formation and attack of Escherichia coli bacteria. [ABSTRACT FROM AUTHOR]

Abstract: To get the low temperature sulfur resistant V2O5/TiO2 catalysts quantum chemical calculation study was carried out. After selecting suitable promoters (Se, Sb, Cu, S, B, Bi, Pb and P), respective metal promoted V2O5/TiO2 catalysts were prepared by impregnation method and characterized by X-ray diffraction (XRD) and Brunner Emmett Teller surface area (BET-SA). Se, Sb, Cu, S promoted V2O5/TiO2 catalysts showed high catalytic activity for NH3 selective catalytic reduction (NH3-SCR) of NO x carried at temperatures between 150 and 400°C. The conversion efficiency followed in the order of Se>Sb>S>V2O5/TiO2 >Cu but Se was excluded because of its high vapor pressure. An optimal 2wt% ‘Sb’ loading was found over V2O5/TiO2 for maximum NO x conversion, which also showed high resistance to SO2 in presence of water when compared to other metal promoters. In situ electrical conductivity measurement was carried out for Sb(2%)/V2O5/TiO2 and compared with commercial W(10%)V2O5/TiO2 catalyst. High electrical conductivity difference (ΔG) for Sb(2%)/V2O5/TiO2 catalyst with temperature was observed. SO2 deactivation experiments were carried out for Sb(2%)/V2O5/TiO2 and W(10%)/V2O5/TiO2 at a temperature of 230°C for 90h, resulted Sb(2%)/V2O5/TiO2 was efficient catalyst. BET-SA, X-ray photoelectron spectroscopy (XPS) and carbon, hydrogen, nitrogen and sulfur (CHNS) elemental analysis of spent catalysts well proved the presence of high ammonium sulfate salts over W(10%)/V2O5/TiO2 than Sb(2%)/V2O5/TiO2 catalyst. [Copyright &y& Elsevier]