Ústav chemie

Browse

Recent Submissions

Now showing 1 - 5 of 52
  • Thumbnail Image
    Item
    Relationship Between Centrifugation and Drying of Sludge and The Organic Halogenes
    (Mendel University in Brno, 2010-05-01) Hrich, Karel; Groda, Bořivoj
    This work is focused on determination of adsorbable organic halogens (AOX) concentration in the digested sludge from the sewage treatment plant and the losses of this component during dewatering and drying of sludge.
  • Thumbnail Image
    Item
    Content changes of adsorbable organically bound halogens during sludge centrifugation and drying
    (Czech Academy of Agricultural Sciences, 2011-03-31) Hrich, Karel; Groda, Bořivoj
    The aim of this work was to calculate the material balance in the treatment process (centrifugation and drying). Control places were chosen and then samples of water and sludge (at the inlet and outlet of the system) were collected. The adsorbable organically bound halogens concentration was detected in these samples by the coulometric method.
  • Thumbnail Image
    Item
    Suitability of denitrifying woodchip bioreactor outflows for use in irrigation
    (Mendel University in Brno, 2017-11-08) Schrimpelová, Kateřina; Malá, Jitka; Bílková, Zuzana; Hrich, Karel
    The contribution is focused on aplication of denitrifying woodchip bioreactor outflow for irrigation of drained area.
  • Thumbnail Image
    Item
    Impedance spectroscopy – comparison of dielectric model with experimental results
    (IOP Publishing, 2023-08-25) Kusák, Ivo; Luňák, Miroslav; Mizerová, Cecílie; Rovnaník, Pavel
    Impedance measurements of building materials have been gaining popularity especially in the last twenty years. No electrical component has only resistance, capacitance or inductance, as there is an interplay of these parameters. This is compounded in the case of building materials, which contain a significant number of different phases that vary in chemical composition, crystalline structure and properties. It is, therefore, necessary to choose a connection and measurement system that provides the most accurate information about the building material. This information is primarily meant to include the complex impedance, its components and the quantities derived from them. The derived quantities are electrical resistance or electrical capacitance. Using these quantities we can point out the composition of the material, its conductivity and identify the percolation threshold or describe its sensory properties in more detail. For measurements, an alternating electric field is crucial, and the range of frequencies depends on the instruments used. For materials characterization, the most used frequency range is 100 Hz to 100 kHz; however, we can measure down to 1 MHz.
  • Thumbnail Image
    Item
    Effect of De-Icing Chemicals on Concrete Scaling: The Role of Storage Water
    (MDPI, 2023-07-10) Misák, Petr; Kocáb, Dalibor; Bayer, Patrik; Vymazal, Tomáš; Rovnaníková, Pavla
    This paper deals with the effect of the character of the water used for the water storage of concrete test specimens on the results of tests for resistance to de-icing chemicals. Two experiments were conducted to investigate the effect of the content of free CO2 in water and leaching of calcium hydroxide from concrete on the test results. In the first experiment, the resistance of mortars to water and de-icing chemicals was investigated. It was found that the character of the water storage, i.e., fresh water vs. previously used water, can significantly affect the test results. The second experiment focused on investigating the effect of the content of free CO2 in water on the test results. It was found that the content of free CO2 in the water can statistically significantly influence the test results. In conclusion, the paper shows that the character of the water used for water storage of concrete test specimens and the content of free CO2 in water are essential factors that can significantly affect the results of concrete resistance tests to de-icing chemicals. Further research is needed to understand these influences and their potential use to improve the resistance of concrete.