Azo dyes decomposition on new nitrogen-modified anatase TiO2 with high adsorptivity
Szczecin University of Technology, Institute of Chemical and Environment Engineering, Department of Water Technology and Environment Engineering, ul. Pułaskiego 10, 70-322 Szczecin, Poland Journal of hazardous materials
(Impact Factor: 4.53).
12/2008; 166(1):1-5. DOI: 10.1016/j.jhazmat.2008.11.024
New vis active photocatalyst was obtained by the modification of commercial anatase TiO2 (Police, Poland) in pressure reactor in an ammonia water atmosphere at 100 °C for 4 h. The photocatalytic activity of new material was tested during three azo dyes decomposition: monoazo (Reactive Read), diazo (Reactive Black) and poliazodye (Direct Green). Obtained photocatalyst had new bands at 1430–1440 cm−1 attributed to the bending vibrations of NH4+ and at 1535 cm−1 associated with NH2 groups or NO2 and NO. UV–vis/DR spectra of photocatalyst had also insignificant decrease in visible region. Fluorescence technique was used for studying the amount of hydroxyl radicals produced on TiO2 surface during visible light irradiation. The hydroxyl radicals produced react with coumarin present in the solution to form 7-hydroxycoumarin which has fluorescent capacity. Photocatalytic activity of modified TiO2 was compared with commercial titanium dioxide P25 (Degussa, Germany). The photocatalytic activity of TiO2/N was higher than that of unmodified material and P25 under visible light irradiation. The ability for dye adsorption (Reactive Red) on photocatalyst surface was also tested. Unmodified TiO2 and P25 has isotherm of adsorption by Freundlich model, and nitrogen-modified TiO2 by Langmuir model. The presence of nitrogen at the surface of TiO2 significantly increased adsorption capacity of TiO2 as well as OH radicals formation under visible radiation.
Available from: Jiangtao Feng
- "Recently, many studies have focused on the adsorption of TiO 2 for its low cost, simple preparation, good stability and non-toxic nature      . Belessi et al.  claimed that the TiO 2 they prepared had the adsorption capacity of 86.96 mg/g for Reactive Red 195. "
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ABSTRACT: While TiO2 has generated great interest in the removal of organic pollutants in recent years, the effect of the surface chemical property of TiO2 on the adsorption performance is unclear. Here, TiO2 samples were prepared in succinic (without hydroxyl group), malic (with one hydroxyl group) and tartaric acid (with two hydroxyl groups) by hydrolysis method and labeled as SU-TiO2, MA-TiO2 and TA-TiO2, respectively. Their adsorption performance for anionic dye-Acid Red G (ARG) and cationic dye-Methylene Blue (MB) was investigated. The adsorption study indicates that the adsorption amount of ARG or MB was proportional to the alkalinity or the acidity, which is related to the number of hydroxyl group of the used acids, of the as-prepared TiO2. Therefore, SU-TiO2 displayed the largest adsorption capacity for ARG, while TA-TiO2 had the highest adsorption capacity for MB. Furthermore, TA-TiO2 can be reused at least 5 times without losing its adsorption capacity.The results indicate that the adsorption mechanism involves in the electrostatic interaction and the electron acceptor-donor interaction.
Available from: Kenji Katayama
- "In contrast, reports on the decomposition of dyes, endocrine disruptors, or humic acid in an aqueous solution using visible light-induced photocatalysis are still fewer in number than those reporting their decomposition in air   . The activity of photocatalysts in water is significantly lower in general compared with that in air because of decreased photoabsorption and aggregation of the photocatalytic particles. "
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ABSTRACT: In this study, a photocatalytic plate bound to highly dispersible silica-doped titanium dioxide (SiT) on a trimethoxysilyl-propyldiethylenetriamine (dien)-coated glass plate (dien-plate) was newly synthesized, and was evaluated by a flow analytical (FA) system, which consists of a photocatalytic reactor and a spectrophotometer, to continuously monitor the absorbance of tested chemicals. The method was not required to collect any sample solution at a constant period. The SiT-dien-plate facilitated the photodecomposition of methylene blue (MB) and indigo carmine (InC) in aqueous solutions. Notably, MB was quantitatively photo-decomposed following 18 h of UV-light irradiation, related to the electrostatic adsorption of surface-bound particles. A water-treatment ability of visible-light-responsive vanadium-modified nitrogen/silica co-doped titanium dioxide fixed on the dien-plate was also evaluated by the FA system. It clarified to decompose MB and InC under visible-light irradiation. Finally, the decomposition of a humic substance dissolved from Middle West China peaty soils by the SiT-dien-plate under UV-irradiation was assessed as applying the FA system with a photocatalytic plate.
Available from: Antoni W Morawski
- "As it can be seen cellulose mixed with 10 wt% of TiO 2 /N catalyst absorbs light stronger than crystalline cellulose, increases absorption under UV to complete 100 % as well as under visible range (400–800 nm) up to 50 %. This could be assigned to the presence of nitrogen in the lattice of TiO 2 (Wawrzyniak and Morawski 2006; Janus et al. 2009) and also because of the yellow colour of new composite. The colour of obtained nanocomposite was noted to be more intensive than precipitated cellulose. "
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ABSTRACT: TiO2/N-cellulose nanocomposite wassuccessfully prepared in the (cyclohexyl)hexyldimethylammonium acetate–dimethyl sulfoxide solution. The obtained composite was characterized with various techniques like UV–Vis/DR, FTIR/DRS, X-ray diffraction, thermogravimetric analysis, DLS method and BET SSA measurements. TiO2/N-cellulose nanocomposite exhibited high UV–Vis light absorption with energy gap shifted to the visibleregion. Additive of TiO2/N photocatalyst to cellulose-IL-DMSO solution leads to obtaining the material with higher thermostability and limited photoactivity
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