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Hydration of biochar prepared by using microwave pyrolysis of municipal sludge
Miklasová, Marta ; Komendová, Renata (referee) ; Kučerík, Jiří (advisor)
Microwave pyrolysis represents a possible solution of municipal sludge disposal. One of the final products of pyrolysis is amorphous porous carbon material called biochar, which can be used in agriculture as a soil amendment. As a rule, biochar is hydrophobic, but its addition can lead to an increase in water holding capacity. However, reasons of this improvement cannot be explained only by its high porosity. This thesis aims to contribute to the understanding the interactions between biochar and water under various environmental-relevant conditions such as direct water addition method and water adsorption from ambient air at different relative humidity. The thermo-analytical methods are common for investigation of the relationship between water and organic materials. One of these methods, differential scanning calorimetry, was used in this thesis. The first experiment was focused on measuring of melting enthalpy of freezable water in biochar pores. The results reflect the influence of pore size and properties of ice structure. The extrapolation of concentration dependence to zero enthalpy was used to determine non-freezing water (0,13–0,15 mg·mg-1 biochar), which reflects microporosity of the biochar. The second experiment was focused on the determination of evaporation enthalpy of water from biochar, which is a measure of the strength of water binding in biochar. This value indirectly reflects the mechanisms of the intake and release of water by biochar. Comparing the results for bound and pure water showed that in biochar is water bound weaker about 10–20 %. This led to conclusion that biochar binds water relatively weakly and the water exchange between biochar and soil is fast, despite the biochar hydrophobicity.
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Influence of different forms of titanium dioxide nanoparticles on soil organic matter properties
Miklasová, Marta ; Řezáčová, Veronika (referee) ; Kučerík, Jiří (advisor)
Nanoparticles present potential risk for environmental compartments including soil. Previous works have been focused on negative effects of nanoparticles on soil biota, however studies about the influence of nanoparticles on soil properties are still limited. This thesis investigates an impact of 20 nm titanium dioxide nanoparticles on selected water properties in soil organic matter exposed to air with various relative humidity. Indeed, at 43, 70 and 95 % dominate different water types, i.e. water adsorbed on soil organic matter, water in water molecular bridges and phase water, respectively. Differential scanning calorimetry (DSC) was used in the study. An important finding is that nanoparticles reduce the stability of water molecular bridges under 70% relative air humidity and generally reduce evaporation enthalpy of water, which represents the ability of the soil to retain water. In the next part the influence of nanoparticles on total water in soil was observed. Under low relative humidity, rutile and anatase affected soil in different ways due to their various hydrophilicity. Under higher relative humidity this effect disappeared. In the last part, ice melting and water evaporation enthalpies of nanoparticle solutions were measured to confirm the presumed effect of nanoparticles on water. The ice melting enthalpy of the solutions was higher relatively to pure water, while the evaporation enthalpy showed a reverse trend (decrease). This confirmed the effects of nanoparticles both for pure water and soil water.
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Influence of different forms of titanium dioxide nanoparticles on soil organic matter properties
Miklasová, Marta ; Řezáčová, Veronika (referee) ; Kučerík, Jiří (advisor)
Nanoparticles present potential risk for environmental compartments including soil. Previous works have been focused on negative effects of nanoparticles on soil biota, however studies about the influence of nanoparticles on soil properties are still limited. This thesis investigates an impact of 20 nm titanium dioxide nanoparticles on selected water properties in soil organic matter exposed to air with various relative humidity. Indeed, at 43, 70 and 95 % dominate different water types, i.e. water adsorbed on soil organic matter, water in water molecular bridges and phase water, respectively. Differential scanning calorimetry (DSC) was used in the study. An important finding is that nanoparticles reduce the stability of water molecular bridges under 70% relative air humidity and generally reduce evaporation enthalpy of water, which represents the ability of the soil to retain water. In the next part the influence of nanoparticles on total water in soil was observed. Under low relative humidity, rutile and anatase affected soil in different ways due to their various hydrophilicity. Under higher relative humidity this effect disappeared. In the last part, ice melting and water evaporation enthalpies of nanoparticle solutions were measured to confirm the presumed effect of nanoparticles on water. The ice melting enthalpy of the solutions was higher relatively to pure water, while the evaporation enthalpy showed a reverse trend (decrease). This confirmed the effects of nanoparticles both for pure water and soil water.
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Hydration of biochar prepared by using microwave pyrolysis of municipal sludge
Miklasová, Marta ; Komendová, Renata (referee) ; Kučerík, Jiří (advisor)
Microwave pyrolysis represents a possible solution of municipal sludge disposal. One of the final products of pyrolysis is amorphous porous carbon material called biochar, which can be used in agriculture as a soil amendment. As a rule, biochar is hydrophobic, but its addition can lead to an increase in water holding capacity. However, reasons of this improvement cannot be explained only by its high porosity. This thesis aims to contribute to the understanding the interactions between biochar and water under various environmental-relevant conditions such as direct water addition method and water adsorption from ambient air at different relative humidity. The thermo-analytical methods are common for investigation of the relationship between water and organic materials. One of these methods, differential scanning calorimetry, was used in this thesis. The first experiment was focused on measuring of melting enthalpy of freezable water in biochar pores. The results reflect the influence of pore size and properties of ice structure. The extrapolation of concentration dependence to zero enthalpy was used to determine non-freezing water (0,13–0,15 mg·mg-1 biochar), which reflects microporosity of the biochar. The second experiment was focused on the determination of evaporation enthalpy of water from biochar, which is a measure of the strength of water binding in biochar. This value indirectly reflects the mechanisms of the intake and release of water by biochar. Comparing the results for bound and pure water showed that in biochar is water bound weaker about 10–20 %. This led to conclusion that biochar binds water relatively weakly and the water exchange between biochar and soil is fast, despite the biochar hydrophobicity.
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