2007

Štengl, V.; Bakardjieva, S.; Murafa, N.; Večerníková, E.; Šubrt, J.; Balek, V., Preparation and characterization of titania based nanowires. Journal of Nanoparticle Research 2007, 9 (3), 455-470.

Abstract: A new method for preparation of titania nanowires with diameter around 10 nm and length up to 2-3 mu m is described. The precursor was prepared from sodium titanate by adding ethylene glycole (EG) and heating at temperature of 198 degrees C for 6 h under reflux. The sodium titanate glycolate formed by this way aggregated into 1D nanostructures and was subsequently transformed into titania glycolate during a chemical treatment with 98% sulfuric acid. Titania nanowires with variable amount of anatase and rutile were prepared by heating to temperatures in the range 350-1000 degrees C. The precursor as well as titania based samples were characterized by X-ray diffraction, Infrared spectroscopy, Scanning electron microscopy, High resolution transmission microscopy, Thermogravimetry, Differential thermal analysis, Evolved gas analysis and Emanation thermal analysis. The nitrogen adsorption/desorption was used for surface area and porosity determination. The photoactivity of the prepared titania samples was assessed by the photocatalytic decomposition of 4-chlorophenol in an aqueous slurry under UV irradiation of 365 nm wavelength. Link

Štengl, V.; Bakardjieva, S.; Murafa, N.; Šubrt, J.; Měsťánková, H.; Jirkovský, J., Preparation, characterization and photocatalytic activity of optically transparent titanium dioxide particles. Materials Chemistry and Physics 2007, 105 (1), 38-46.

Abstract: The transparent particles of titanium dioxide (anatase or brookite modification) was prepared by hydrolysis of aqueous solution of titanium(III) chloride in the presence of polyethyleneglycol. The prepared samples were characterized by measurement of particle size distribution and selected area electron diffraction (SAED), morphology and microstructure were obtained by HRTEM. The crystallinity of the samples and its photocatalytic activity increased with the time of ageing in the aqueous solutions up to 60 days. Photocatalytic activity of prepared samples of titanium dioxide was determined by degradation of aqueous solution of Orange II dye under UV radiation, in comparison to Degussa P25 photocatalyst. Link

Houšková, V.; Štengl, V.; Bakardjieva, S.; Murafa, N.; Kalendová, A.; Opluštil, F., Zinc oxide prepared by homogeneous hydrolysis with thioacetamide, its destruction of warfare agents, and photocatalytic activity. Journal of Physical Chemistry A 2007, 111 (20), 4215-4221

Abstract: Zinc sulfide (ZnS) nanoparticles were prepared by homogeneous hydrolysis of zinc sulfate and thioacetamide (TAA) at 80 °C. After annealing at a temperature above 400 °C in oxygen atmosphere, zinc oxide (ZnO) nanoparticles were obtained. The ZnS and ZnO nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and Brunauer−Emmett−Teller (BET)/Barrett−Joyner−Halenda (BJH) methods were used for surface area and porosity determination. The photocatalytic activity of as-prepared zinc oxide samples was determined by decomposition of Orange II dye in aqueous solution under UV irradiation of 365 nm wavelength. Synthesized ZnO were evaluated for their non-photochemical degradation ability of chemical warfare agents to nontoxic products. Link

Houšková, V.; Kalendová, A.; Štengl, V.; Bakardjieva, S., Synthesis and properties of morphologically interesting particles of zincite and periclase. Journal of Physics and Chemistry of Solids 2007, 68 (5-6), 1198-1202.

Abstract: Various particles based on zincite and periclase were prepared by thermal methods. In dependence on starting compounds, particles varying in shape and size were obtained. Synthesized particles were identified and determined by X-ray diffraction and Scanning Electron Microscope (SEM). Morphologically interesting particles of ZnO, MgO and ZnO, MgO layers on selected mineral carriers were applied to organic coatings for determination of its anticorrosive properties. Link

Houšková, V.; Štengl, V.; Bakardjieva, S.; Murafa, N.; Kalendová, A.; Opluštil, F., Nanostructure materials for destruction of warfare agents and eco-toxins prepared by homogeneous hydrolysis with thioacetamide: Part 1 - zinc oxide. Journal of Physics and Chemistry of Solids 2007, 68 (5-6), 716-720.

Abstract: Zinc sulphide (ZnS) nanoparticles were prepared by homogeneous hydrolysis of zinc sulphate and thioacetamide (TAA) at 80 °C. After annealing at temperature above 400 °C in oxygen atmosphere, zinc oxide (ZnO) nanoparticles were obtained. The ZnS and ZnO nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission microscopy (HRTEM), selected area electron diffraction (SAED), by BET and BJH methods used for surface area and porosity determination. The photocatalytic activity of the as-prepared ZnO samples was determined by the decomposition of Orange II in the aqueous solution under UV irradiation of 365 nm of wavelength. Link

Danek, O.; Štengl, V.; Bakardjieva, S.; Murafa, N.; Kalendová, A.; Opluštil, F., Nanodispersive mixed oxides for destruction of warfare agents prepared by homogeneous hydrolysis with urea. Journal of Physics and Chemistry of Solids 2007, 68 (5-6), 707-711.

Abstract: Nanocrystalline mixed oxides of Ti, Zn, Al and Fe were prepared by a homogeneous hydrolysis of sulphates with urea at temperature of 100 °C in an aqueous solution. The prepared samples were characterized by BET and BJH measurements, an X-ray powder diffraction and scanning electron microscopy. These oxides were taken for an experimental evaluation of their reactivity with yperite (2,2′-dichloroethyl sulphide), soman (3,3-dimethyl-2-butyl methylphosphonofluoridate) and matter VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothionate). An excellent activity in decomposition of chemical warfare agents was observed in these materials (conversion degree higher then 96%/h). Link

Bakardjieva, S.; Štengl, V.; Šubrt, J.; Houšková, V.; Kalenda, P., Photocatalytic efficiency of iron oxides: Degradation of 4-chlorophenol. Journal of Physics and Chemistry of Solids 2007, 68 (5-6), 721-724

Abstract: The photocatalytic activity of ferrihydrite Fe5O7(OH)×4H2O synthesized by homogeneous precipitation with urea and products obtained by calcinations of as-precipitated ferrihydrite at different temperatures (200–1000 °C) was studied. The microstructure and surface properties of raw precipitate and all heated samples were characterized by means of HRTEM, SEM, BET/BJH and RTG analyses. Kinetics of disappearance of 4-chlorophenol (4-CP) in aqueous solution was used as a test reaction. We have found that hematite Fe2O3 obtained at 1000 °C exhibited satisfied photocatalytic efficiency on the degradation of 4-CP. Link

Štengl, V.; Bakardjieva, S.; Šubrt, J.; Opluštil, F.; Olšanská, M., Nanodisperse oxides and hydroxides for destruction of warfare agents. Chemicke Listy 2007, 101 (12), 1045-1050

Abstract: Homogeneous hydrolysis of titanyl sulfate and iron (III) sulfate have been used to prepare anatase and ferrihy- drite, respectively, with high specific surface areas. The resulting oxides were characterized by nitrogen adsorption (BET) and porosity (BJH), X-ray diffraction and scanning electron microscopy. The reactivity of the oxides with yperite, soman (1,2,2-trimethylpropyl methylphospho- nofluoridate) and VX(S-2-(diisopropylamino)ethyl O-ethyl methylphosphonothioate. The conversion to non- toxic products was highest for yperite (99 %). Link