Time filter

Source Type

Ústí nad Labem, Czech Republic

Cmelik J.,Research Institute of Inorganic Chemistry Inc. | Nainarova Z.,J.E. Purkyne University in Usti nad Labem | Rysanek P.,Research Institute of Inorganic Chemistry Inc.
International Journal of Environmental Analytical Chemistry | Year: 2015

The developed and tested method is based on the acid volatile sulphur (AVS) releasing from a sample of sediment by acidification with hydrochloric acid and sequential absorption of released hydrogen sulphide into the absorption solution of sodium hydroxide. Total sulphur absorbed in the absorption solution is subsequently determined by inductively coupled plasma optical emission spectrometry (ICP-OES) technique. The method was tested using both model and real samples of the river sediment. Obtained results were compared with the results of iodometric determination as the method routinely used for the AVS determination. In case of using ICP-OES with purge and trap, there is no spectral interference of calcium; therefore for the determination of sulphur, it is possible to use atomic emission line of sulphur S I 180.7 nm. The tested method provides the results comparable with the iodometric method within the range of tested concentrations. The detection limit (LOD) of this method is 0.09 mg· S2 − ∙ L−1 in the absorption solution which corresponds to 0.23 mg S2 −·kg−1 in a sediment. Value of LOD is comparable with the iodometric determination. © 2015 Taylor & Francis. Source

Bortnovsky O.,Research Institute of Inorganic Chemistry Inc. | Bezucha P.,Research Institute of Inorganic Chemistry Inc. | Sazama P.,J. Heyrovsky Institute of Physical Chemistry | Dedecek J.,J. Heyrovsky Institute of Physical Chemistry | And 2 more authors.
Ceramic Engineering and Science Proceedings | Year: 2010

Geopolymers are generally XRD-amorphous materials; however recent research has proved that they contain nanometer particles probably with zeolitic structure. It has also been confirmed in our investigation that sodium in metakaolin-based geopolymer could be easily exchanged for other cations such as ammonium, cobalt, copper etc. Moreover, according to UV-VIS spectra of Co-geopolymer, it has been proven that the local arrangements of Co 2+- extraframework ions in cationic positions correspond to those known in high-silica zeolites, such as mordenite, ZSM-5 or beta. A similar high level of ion exchange with various ions of transition metals has also been reached for metakaolin-slag-based geopolymers. Accordingly, it could be truly expected that these metal-exchanging geopolymers would show similar properties and potential applications as zeolites, while keeping the advantages of the geopolymers, such as simple synthesis procedure, easy molding into complicated shapes or forming thin highly adhesive layers. These novel applications, such as heterogeneous catalysis for environmental applications and active antibacterial thin coating of metal-geopolymers will be presented and discussed. Source

Stekrova M.,Abo Akademi University | Stekrova M.,Research Institute of Inorganic Chemistry Inc. | Stekrova M.,Institute of Chemical Technology Prague | Kumar N.,Abo Akademi University | And 6 more authors.
Reaction Kinetics, Mechanisms and Catalysis | Year: 2013

High selectivity (82 %) to 3-methyl-6-(prop-1-en-2-yl)cyclohex-3-ene- 1,2-diol, a potent anti-Parkinson drug, was achieved in the isomerization of verbenol oxide at the conversion level of 96 % in N,N-dimethylacetamide at 140 °C over a metal modified zeolite, Fe-Beta-300 with SiO2 to Al2O3 ratio of 300. This catalyst exhibits both weak and medium strong Brønsted and Lewis acid sites. © 2013 Akadémiai Kiadó, Budapest, Hungary. Source

Stekrova M.,Abo Akademi University | Stekrova M.,Institute of Chemical Technology Prague | Stekrova M.,Research Institute of Inorganic Chemistry Inc. | Kumar N.,Abo Akademi University | And 3 more authors.
Catalysis Today | Year: 2014

The isomerisation of α-pinene oxide has been intensively investigated for selective preparation of campholenic aldehyde, a compound used in the synthesis of fragrances. Selective preparation of another product of α-pinene oxide rearrangement, trans-carveol, still remains a challenging task. Trans-carveol is a highly valuable compound used in perfume bases, food flavour compositions and as an active pharmaceutical substance in chemoprevention of mammary carcinogenesis. In the present work zeolite beta with different SiO2/Al2O3 molar ratios was modified by iron, characterised and tested per se and in the modified form for trans-carveol preparation from α-pinene oxide. The isomerisation reaction was carried out in a polar basic solvent N,N-dimethylacetamide at 140 °C. The activities and selectivities of the catalysts were correlated with their acid properties and with the iron content. © 2014 Elsevier B.V. All rights reserved. Source

Stekrova M.,Abo Akademi University | Stekrova M.,Institute of Chemical Technology Prague | Stekrova M.,Research Institute of Inorganic Chemistry Inc. | Kumar N.,Abo Akademi University | And 8 more authors.
Applied Catalysis A: General | Year: 2014

α-Pinene oxide, an oxygenated derivative of α-pinene, can be converted into various valuable substances useful as flavour, fragrance and pharmaceutical compounds. Campholenic aldehyde is one of the most desired products of α-pinene oxide isomerization being a valuable intermediate for the production of sandalwood-like fragrances. Iron modified zeolites Beta-75 and ZSM-5, mesoporous material MCM-41, silica and alumina were prepared by two methods (impregnation and solid-state ion exchange) and tested for selective preparation of campholenic aldehyde by isomerization of α-pinene oxide. The characterization of tested catalyst was carried out using scanning electron microscope analysis, nitrogen adsorption measurements, pyridine adsorption-desorption with FTIR, X-ray absorption spectroscopy measurements, XPS-analysis, 29Si MAS NMR and 27Al MAS NMR and X-ray diffraction. The isomerization of α-pinene oxide was carried out in toluene as a solvent at 70 C. The main properties influencing the activity and the selectivity are the acidic and structural properties of the tested catalysts. The highest selectivity of 66% was achieved at complete conversion of α-pinene oxide with Fe-MCM-41. © 2013 Elsevier Ltd. All rights reserved. Source

Discover hidden collaborations