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Study of hydration of biocolloids
Hývnarová, Lucie ; Sedláček, Petr (referee) ; Klučáková, Martina (advisor)
The subject of this master’s thesis was to examine the hydration properties of selected biocolloids. Specifically, humic substances (fulvic and humic acids), hyaluronic acids in three molecular weights, dextran and chitosan were investigated. Hydration properties of selected biocolloid substances were studied by various methods. The influence of water content during the dissolution of substances and the different time for which water acted on biocolloids were studied. Differential scanning calorimetry DSC measurements resulted in enthalpies and crystallization and melting points. Heat fluxes resulted in the use of perfusion calorimetry. TGA thermogravimetric analysis was used to determine the moisture content of the bioolloids used, after measuring the perfusion calorimeter.
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Development of methods for fast soil analysis
Křivánková, Zuzana ; Doležalová Weissmannová, Helena (referee) ; Kučerík, Jiří (advisor)
The submitted diploma thesis aims to extend the use of thermogravimetry for the analysis of organic C and total N contents in soils. The advantages of thermogravimetry in comparison to conventional analytical methods are that it is a versatile technique that provides fast analysis, does not require sample pretreatment and chemicals– and can be used for the analysis of various soil types. The research work performed so far showed correlations between thermogravimetric data and some soil properties. In the past, intact soils exposed to 76% relative humidity (RH) were analyzed by thermogravimetry for these purposes. However, this humidity is problematic to achieve and maintain for most thermogravimeters. Recent work has shown that correlations can be observed in agricultural land exposed to lower RH. Therefore, it can be assumed that a correlation between TG data exists in soils exposed to any RH. TG could then be used to analyze soil properties under any known RH conditions. The aim of this work was to verify this hypothesis and try to incorporate knowledge of RH into the relationships between TG and soil properties. For this reason, intact soils exposed to the relative humidity of 30, 55, and 76% were analyzed in this work. It was demonstrated the dependence between organic C content and mass loss between 320 and 330°C as well as total nitrogen content and mass loss between 410 and 420°C independently of relative humidity. Based on that knowledge, we have derived equations enabling determination of the content of organic C and total N for RH ranging 43% - 76% using mass losses and knowledge of RH. Nevertheless, due to the low number of tested RH, the equations are still only preliminary and need to be improved by analyzing soil samples at a larger number of RH.
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Determination of moisture content in electrical insulating materials
Šebesta, Petr ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This work is based on determination of moisture content in electrical insulating materials materials and ways to measure the moisture. In the theoretical section describes the methods of thermal analysis, and subsequently described in detail Thermogravimetry method, which is used in the measurement. Measurements are made using the Moisture Analyzer RADWAG 60 W/H connected with a PC, using a variety of samples from inorganic to organic. A great variety of samples was chosen because of demonstrations thermogravimetric methods and a better understanding of wetting and drying of different materials.
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Detection of PET microplastics in soils
Kameníková, Eliška ; Doležalová Weissmannová, Helena (referee) ; Kučerík, Jiří (advisor)
The use of plastics leads to their gradual degradation and consequently to the formation of microplastics, i.e. the millimeter sized particles, which have been shown to cause environmental problems. Currently, the microplastics detection studies are focused on aquatic environments, but the investigation of microplastics in soils is still limited by the lack of appropriate analytical methods. The aim of this thesis was to verify the possibility to detect the PET microplastics in different soil types based on the results obtained by using thermogravimetry. Thermogravimetry data were evaluated in two ways, using a blank soil sample and using a recalibrated universal soil standard. The results showed that the thermo-oxidative properties of PET microplastics were not influenced by soil type, but vice versa, PET has affected the thermo-oxidative behavior of soils and soil processes. Furthermore, it was confirmed that recalibrated equations of the universal soil model can be used to analyze microplastics in soils.
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Influence of biodegradation of polyhydroxyalkanoates on soil properties and composition
Denková, Pavla ; Doležalová Weissmannová, Helena (referee) ; Kučerík, Jiří (advisor)
Biodegradable plastics are presented as a promising replacement for synthetic polymers. In soil, they are expected to be fully degraded by micro-organisms within a short time and to be inherently harmless to the environment. However, this assumption needs to be verified, and it is important to pay attention to the impact on soil´s biota as well as the effect of the biodegradation process could have on soil properties, composition and structure. In this work was studied the effect of biodegradation of poly(R-3-hydroxybutyrate), (P3HB), belonging to the group of polyhydroxyalkanoates, on the structure and physicochemical properties of soil. P3HB particles were mixed in different concentrations with soil in which biodegradation experiments were carried out under different conditions - i.e. with and without growing plant, with and without nitrogen fertilization. After 90 days, were soil analyzed. Thermogravimetry was used to determine the amount of residual non-degraded micro-bioplastics and to determine the effect of biodegradation on the properties of soil organic matter. Differential scanning calorimetry provided information on the effect of biodegradation on the evaporation enthalpy of adsorbed water from the soil, while the amount of water in the soil was also determined. Furthermore, the effect on field water holding capacity was determined and sieve analysis of individual samples was performed to characterize the effect of biodegradation on soil particle size distribution. Biodegradation conditions were shown to affect not only the rate of biodegradation but also some soil parameters. As expected, biodegradation of P3HB was proved to be faster in a nutrient-rich environment. In contrast, lack of nitrogen in soil with growing plant caused a decrease in the evaporation enthalpy of water and a reduction in the amount of water in soil, which can lead to easier soil drying and cause stress conditions for plant growth. Increased soil particle aggregation was observed in all sample series with P3HB compared to soils without P3HB addition.
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Mechanical properties and structure of blends of recycled polyethylene with linear low density polyethylene
Kocandová, Jana ; Poláček, Petr (referee) ; Bálková, Radka (advisor)
Recycled material produced during three months from packing polyethylene foils coming from three suppliers was analysed together with one recycled material under complaint from the point of melt flow index (MFI), composition and mechanical properties. The addition of linear low density polyethylene (LLDPE) into the recycled material was studied as well. It was measured melt flow index (MFI), Differential scanning calorimetry (DSC) together with Thermogravimetry methods were used to determine composition. Selected materials were pressed to obtain films with the thickness of 1 mm to determine tensile properties. Recycled materials contained 40–65% LLDPE, small amount of polypropylene as well as chalk. The content of LDPE and LLDPE varied within one supplier and thus mechanical properties did. The results showed the difference in quality of PE films separation among all suppliers. The problems with workability of material under complaint were caused by the material composition – the amount of LLDPE predominated. The addition of LLDPE into the recycled material in the range of 5–20 % increased MFI by 13-78%. Mechanical properties of blends rich in LLDPE were similar to those of clear LLDPE. The presence of LDPE influenced more markedly only the strength to break. The blends of LDPE and LLDPE were evaluated as immiscible but with high affinity of the components with increasing contend of LLDPE. No material was chemically degraded. The methods commonly performed in manufacture, especially MFI, are not able to differentiate LDPE form LLDPE – recommended is DSC.
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Identification of PET particles in soils and their influence on the environment
Šudomová, Lucie ; Svěrák, Tomáš (referee) ; Slovák, Václav (referee) ; Kučerík, Jiří (advisor)
This thesis is focused on several issues connected with plastics and their impact on the environment. Although plastics are produced for a relatively short time, they have taken a dominant position in almost all industries and aspects of everyday life. However, this causes significant challenges related especially to the waste management. If plastics are not handled properly, they can contaminate the environmental compartments where they are gradually defragmented and degraded, and macro and microplastics are formed. Both qualitative and quantitative analysis of microplastics in soil is a big challenge. In this work, it is introduced a new method based on mutual relationships between soil components called Soil Universal Model Method (SUMM). The method allowed to identify and quantify some types of microplastics in the untreated soil. It appeared to be effective in the analysis of PET, PVC and PP. A pilot study on the influence of PET microplastics on soil revealed negative effects, which include soil organic matter deterioration and faster desiccation. In addition, it was observed a gradual assimilation of PET into the soil matrix, and possible degradation, in particular at low pH values. To identify the origin of PET fragments occurring in nature it was developed a method based on PET thermophysical properties (determined using Differential Scanning Calorimetry, DSC) and advanced statistical methods. This method appeared to be effective also for the assessment of PET quality in recycling loop and classifies the PET into four groups. It was also found that controlled thermal degradation under laboratory conditions does not correlate with natural PET degradation (aging). A method based on spectroscopic parameters (FTIR) is also presented here, but it did not achieve such unambiguous results as using DSC, because it determines the molecular structure of the polymer, which proved to be insufficient for identifying changes during the PET recycling cycle.
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Influence of titanium dioxide nanoparticles on soil properties
Zoufalá, Anna ; Řezáčová, Veronika (referee) ; Kučerík, Jiří (advisor)
This masters thesis deals with the influence of TiO2 nanoparticles on soil properties. Even though synthetic nanoparticles pose potential environmental risk, their impact on the environment is not researched enough. TiO2 nanoparticles are one of the most used and widespread nanoparticles and contamination of the environment with these nanoparticles is inevitable. One of the properties, thanks to which these nanoparticles are used, is the possibility of photocatalysis when the nanoparticles are illuminated with light in the UV wavelength. During this process, especially in the presence of water, highly reactive radicals are formed, which can oxidize organic compounds, which is mainly used for the degradation of organic pollutants. Therefore it is possible that in soil contaminated with TiO2 nanoparticles photocatalytic degradation of soil organic matter could occur. On the other hand, it is possible that polymerization reactions occur too. Thus the aim of this work is to clarify which processes occur after irradiating soil contaminated with TiO2 nanoparticles. To asses the impact of TiO2 nanoparticles and UV irradiation were caried out experiments during which soil contaminated with TiO2 nanoparticles was irradiated at different humidities. These samples were analyzed using thermogravimetry and FTIR spectrometry. No changes caused by TiO2 nanoparticles and UV light were detectable using thermogravimetry. Data acquired from FTIR spectrometry were processed using two different statistical methods – correlation analysis and principal components analysis. Correlation analysis was found not to be suitable method of data evaluation for the purpose of this work. Principal components analysis proved, that higher concentration of nanoparticles (5 wt. %) in combination with UV light does have impact on the composition of soil organic matter and its decomposition occurs mainly.
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Study of hydration of biocolloids
Hývnarová, Lucie ; Sedláček, Petr (referee) ; Klučáková, Martina (advisor)
The subject of this master’s thesis was to examine the hydration properties of selected biocolloids. Specifically, humic substances (fulvic and humic acids), hyaluronic acids in three molecular weights, dextran and chitosan were investigated. Hydration properties of selected biocolloid substances were studied by various methods. The influence of water content during the dissolution of substances and the different time for which water acted on biocolloids were studied. Differential scanning calorimetry DSC measurements resulted in enthalpies and crystallization and melting points. Heat fluxes resulted in the use of perfusion calorimetry. TGA thermogravimetric analysis was used to determine the moisture content of the bioolloids used, after measuring the perfusion calorimeter.
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Influence of biodegradation of polyhydroxyalkanoates on soil properties and composition
Denková, Pavla ; Doležalová Weissmannová, Helena (referee) ; Kučerík, Jiří (advisor)
Biodegradable plastics are presented as a promising replacement for synthetic polymers. In soil, they are expected to be fully degraded by micro-organisms within a short time and to be inherently harmless to the environment. However, this assumption needs to be verified, and it is important to pay attention to the impact on soil´s biota as well as the effect of the biodegradation process could have on soil properties, composition and structure. In this work was studied the effect of biodegradation of poly(R-3-hydroxybutyrate), (P3HB), belonging to the group of polyhydroxyalkanoates, on the structure and physicochemical properties of soil. P3HB particles were mixed in different concentrations with soil in which biodegradation experiments were carried out under different conditions - i.e. with and without growing plant, with and without nitrogen fertilization. After 90 days, were soil analyzed. Thermogravimetry was used to determine the amount of residual non-degraded micro-bioplastics and to determine the effect of biodegradation on the properties of soil organic matter. Differential scanning calorimetry provided information on the effect of biodegradation on the evaporation enthalpy of adsorbed water from the soil, while the amount of water in the soil was also determined. Furthermore, the effect on field water holding capacity was determined and sieve analysis of individual samples was performed to characterize the effect of biodegradation on soil particle size distribution. Biodegradation conditions were shown to affect not only the rate of biodegradation but also some soil parameters. As expected, biodegradation of P3HB was proved to be faster in a nutrient-rich environment. In contrast, lack of nitrogen in soil with growing plant caused a decrease in the evaporation enthalpy of water and a reduction in the amount of water in soil, which can lead to easier soil drying and cause stress conditions for plant growth. Increased soil particle aggregation was observed in all sample series with P3HB compared to soils without P3HB addition.
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