Efficiency of sensitizing nanotitania with organi

Authors: Elena Savinkina Lubov Obolenskaya Galina Kuzmicheva

Publish Date: 2014/03/05

Volume: 5, Issue: 1, Pages: 125-133

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Abstract

A new method of sensitizing titania by treatment of the reaction mixture with Methylene Blue Methyl Red or hydrogen peroxide is developed the sensitizer was introduced into the reaction mixture while synthesizing nanosize TiO2 from titanyl sulfate The samples prepared by this method are compared to the samples prepared by cold impregnation of Methylene Blue Methyl Red or hydrogen peroxide on titania presynthesized by sulfate method or commercial Degussa P25 and Hombikat UV100 The samples were characterized by Xray diffraction their photocatalytic activity was studied in the model reaction of Methyl Orange decomposition in aqueous solution under UV and visible light The highest photocatalytic activity under visible light was found for titania sensitized with titanium peroxo complexes by the new method It is also active for photodegradation of salicylic acid under visible lightNanosize titania is the most promising photocatalyst due to efficient photoactivity high stability and low toxicity Titania has been used for energy conversion and photodegradation of many contaminants under UV radiation its photocatalytic properties in this region are well studied Hashimoto et al 2007 To utilize visible light various methods were used to modify TiO2 including doping and photosensitization Carp et al 2004 Banerjee 2011 Viswanathan and Krishnamurthy 2012Inorganic sensitizers organic dyes and coordination metal complexes are very effective sensitizers that were studied mostly Fujishima and Rao 1998 Sauvé et al 2000 Pei and Luan 2012 Zhou et al 2012 Epling and Lin 2002 investigated photoassisted bleaching of 15 dyes utilizing TiO2 and visible light good rate for Methylene Blue MeB decomposition can be explained by titania sensitization the MeB photobleaching rates were anatase  amorphous titania  rutile Hussein and Alkhateeb 2007 sensitized titanium dioxide by impregnation of organic dyes on the commercial photocatalyst Degussa P25 The photooxidation of benzyl alcohol was found to be in the sequence riboflavin  Safranin O  naked TiO2  Methyl Red MeR  Eosin B  Methylene Blue Dye sensitization is usually accompanied by such problems as dye desorption and backward transfer recombination during the photoreaction Zhang et al 2012 Houas et al 2001 presented a detailed reaction mechanism from the initial step of adsorption involving the cationic functional group of MeB molecule which is probably adsorbed perpendicularly to the surface down to the final products CO2 SO42− NH4+ and NO3−Titanium is known to form yellowcolored peroxo complexes Zou et al 2009 prepared H2O2sensitized sulfated titania nanoparticles with a response to visible light by introduction of hydrogen peroxide into a photoreactor containing titania and Methyl Orange MeO degradation of MeO was completed in 4 h A sol–gel technique using the peroxo titanic acid sol as a precursor for fabrication of the TiO2 photocatalytic films is reported the peroxo titanic acid sol was synthesized from titanyl sulfate Ge and Xu 2007 or titaniumIV tetrabutoxide Sonawane et al 2003 and H2O2 solution The films showed high photocatalytic activity under UV light however no experiments using visible light were carried out in these works Karuppuchamy and Jeong 2006 prepared amorphous powder of titanium peroxo complex from TiOSO4 and H2O2 at room temperature which was then converted to anatase by heat treating at 300 °C photocatalytic activity of the product was not studiedThe purpose of the work was to prepare sensitized photocatalysts on the basis of titanium dioxide using organic and inorganic compounds by various methods and studying their photocatalytic activity in the model reactions of MeO and salicylic acid degradation

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