CMV laboratoř biokoloidů

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    Biochar Texture – A Parameter Influencing Physicochemical Properties, Morphology, and Agronomical Potential
    (MDPI, 2022-07-28) Kalina, Michal; Sovová, Šárka; Hajzler, Jan; Kubíková, Leona; Trudičová, Monika; Smilek, Jiří; Enev, Vojtěch
    Biochar represents a stable form of carbon-rich organic material produced by the pyrolysis of various biomass residues. It has the potential to stabilize organic carbon in the soil and improve soil fertility, water retention, and enhance plant growth. Despite its potential, there is limited information on the mutual relation of biochar texture with its physicochemical characteristics, morphology, and the content of organic matter. For these reasons, we studied three biochar samples with potential use in agriculture as soil supplements (NovoCarbo, Sonnenerde, Bi-ouhel.cz). Our experimental approach performed on the individual sieved fraction of studied biochars (<0.5; 0.5–2.0; 2.0–4.0 and >4.0 mm) confirmed the importance of a selection of optimal source biomass material as the content of lignin, cellulose, and hemicellulose, together with the conditions of pyrolysis (temperature of pyrolysis), play a crucial role in the managing of the properties of produced biochar. Agronomically more stable biochars containing a higher con-tent of organic matter and organic carbon, with alkaline pH response and well-developed aro-matic porous structure, could be produced from lignin-based biomass residues at higher pyroly-sis temperatures, which is an important finding taking into account the possible utilization of biochar in soils as a soil conditioner.
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    Thermodynamic Analysis of the Landolt-Type Autocatalytic System
    (MDPI, 2021-10-28) Pekař, Miloslav
    A recent work demonstrated on the example of the Landolt-type reaction system how the simplest autocatalytic loop is described by the kinetic mass action law and proper parametrization of direct and autocatalytic pathways. Using a methodology of non-equilibrium thermodynamics the thermodynamic consistency of that kinetic model is analyzed and the mass action description generalized including an alternative description by the empirical rate equation. Relationships between independent and dependent reactions and their rates are given. The mathematical modeling shows that following the time evolution of reaction rates provides additional insight into autocatalytic behavior. A brief note on thermodynamic driving forces and coupling with diffusion is added. In summary, this work extends and generalizes the kinetic description of the Landolt-type system placing it within the framework of non-equilibrium thermodynamics and demonstrating its thermodynamic consistency.