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Kaneva N.V.,Laboratory of Nanoparticle Science and Technology | Yordanov G.G.,Laboratory of Nanoparticle Science and Technology | Dushkin C.D.,Laboratory of Nanoparticle Science and Technology
Bulletin of Materials Science | Year: 2010

Patterned thin films, ZnO, are successfully prepared on glass substrates by the sol-gel method using dip-coating technique. The films, formed of ZnO nanocrystallites with hexagonal crystal structure, are characterized by means of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The as obtained ZnO films are studied with respect to photo-initiated bleaching of malachite green in aqueous solutions. The bleaching process is investigated at various initial concentrations of malachite green in the aqueous solutions by using ZnO films of different thicknesses. The obtained results are promising for the development of ZnO photocatalysts by the sol-gel method. © Indian Academy of Sciences.

Kaneva N.V.,Laboratory of Nanoparticle Science and Technology | Dushkin C.D.,Laboratory of Nanoparticle Science and Technology | Bojinova A.S.,Laboratory of Nanoparticle Science and Technology
Bulgarian Chemical Communications | Year: 2012

Here we present thin films of ZnO with photocatalytic application in purifying water from organic pollutants. The films were obtained from stable colloidal precursor sol, prepared by two sol-gel methods (A and B) using zinc acetate and varying the solvents. These sols are deposited on glass substrates via dip-coating technique. The films are characterized by different methods (XRD, SEM, FTIR). By XRD was established that the zinc oxide is of hexagonal crystal structure. A comparison of the determined morphology, composition and structure for the prepared by two different method films is studied. The morphology of films obtained with 1-propanol and 1-butanol, as shown is not homogeneous. The film surface is not uniform and there are many cracks and bubbles. Layers in such films is very easy to peel off after their ignition. Therefore, a third synthesis of the sol-gel method A is performed, with any changes in the formulation, only alcohol is substituted by 2-propanol. There is ganglia typical surface structure of the so obtained film, which is established by SEM. They are evenly distributed over the entire film surface. The film surface in the sol-gel B was investigated by SEM. The film surface has characteristic ganglia-like patterns. The resulting samples are more uniform, show much better adhesion of the layers and higher density, compared to films from the sol-gel method A. The difference in the films morphology has influence their photocatalytic performance. © 2012 Bulgarian Academy of Sciences, Union of Chemists in Bulgaria.

Siuleiman S.,Laboratory of Nanoparticle Science and Technology | Kaneva N.,Laboratory of Nanoparticle Science and Technology | Bojinova A.,Laboratory of Nanoparticle Science and Technology | Papazova K.,Laboratory of Nanoparticle Science and Technology | And 2 more authors.
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2014

The present study is focused on photocatalytic degradation of the organic azo-dye Orange II in water solutions using TiO2 and ZnO powders or bare and TiO2 doped ZnO nanowire thin films. Commercial anatase TiO2 and ZnO are used for the photocatalytic experiments in slurry. The ZnO seeded substrates are prepared by repetition of four seed deposition cycles from zinc acetate solution using spin coating technique. The ZnO nanowires array films are obtained via wet chemical method. The ZnO and TiO2 doped ZnO nanowire thin films are investigated by SEM and X-ray diffraction. The photocatalytic tests are performed in cylindrical glass reactors under UV or visible light irradiation. The pollutants concentrations are 20ppm Orange II for slurry and 10ppm for film photocatalysis. The dyes photodegradation is observed spectrophotometrically. © 2014 Elsevier B.V.

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