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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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Influence of bioplastics´ biodegradation on soil quality
Paluchová, Natálie ; Doležalová Weissmannová, Helena (referee) ; Kučerík, Jiří (advisor)
V poslední době se pozornost polečnosti obrátila k mikroplastům. Jsou produkovány různými odvětvími a šíří se napříč prostředím. Po dlouhou dobu byly považovány za inertní, bez dalšího vlivu na rostliny a jiné živé organismy, avšak jak zjistily nedávné studie, mohly by představovat vážnou hrozbu. Několik vědců, včetně nás, se proto začalo soustředit na jejich transport a transformace v životním prostředí. Většina se však zaměřuje pouze na jejich přítomnost v mořských a sladkých vodách, a proto jejich chování ve vzduchu a půdě zůstává nejasné. Kromě toho byla pozornost soustředěna i na bioplasty. Jsou prezentována jako ekologická alternativa, která má vyřešit všechny dosud zmíněné problémy (a další). Avšak často se zapomíná, že jejich hlavní výhoda může být zároveň nevýhodou. Z tohoto důvodu se tato diplomová práce zaměřuje na negativní účinky spojené s přítomností mikroplastů (konkrétně bioplastu poly-(R)-3-hydroxybutyrátu) v půdě jako jejich běžný receptor. Kombinovali jsme respirometrii, elementární analýzu, termogravimetrii a enzymatické testy, abychom zkoumali fyzikálně-chemické změny v půdě vyvolané přítomností bioplastu. Naše výsledky ukázaly negativní vliv na půdní organickou hmotu a zadržování vody v půdě. V tomto smyslu byl zkoumán i tzv. "priming effect", jelikož docházelo k urychlení a také zpomalení rozkladu půdní organické hmoty. Zaznamenali jsme rozdílný vliv vybraných koncentrací biopolymeru na půdu a také vliv půdních vlastností na průběh degradace. V neposlední řadě zvýšení enzymatické aktivity jasně naznačovalo vliv přítomnosti biopolymeru na mikrobiální komunitu. Na základě takových zjištění jsme došli k závěru, že přidání biopolymeru vede k dlouhodobému dopadu na řadu funkcí půdního ekosystému.
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Derivatization of Sodium Hyaluronate as a Possible Tool for Increasing of the Stability of Model Artificial Synovial Fluid
Hrochová, Eliška ; Mravec, Filip (referee) ; Kalina, Michal (advisor)
This master thesis deals with the optimization of the procedure of modification of hyaluronic acid structure for the use in the artificial synovial liquids. Based on the literature research, the amino acid alanine was used for the modification of carboxylic group in the glucuronic acid. The main subject of study is the improvement of the stability and mechanical properties of synovial liquid. DLS microrheology, macrorheology, thermogravimetric analysis (TGA), multi-angle light scattering with flow-field flow fractionation (AF4-MALS) and infrared spectroscopy (FTIR) were used for characterization. The theoretical part of this theses submits review of the musculoskeletal system, role of hyaluronic acid in metabolism and summary of synovial liquid. The experimental part focuses on the measurement of the stability and mechanical properties of three artificial samples (first with no modification, second with modified hyaluronic acid and third with modified hyaluronic acid and chondroitin sulphate). These samples were compared with real horse synovial fluid and artificial viscosupplement Orthovisc®.
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Fate of microplastics in soil
Kameníková, Eliška ; Řezáčová, Veronika (referee) ; Kučerík, Jiří (advisor)
The problems with microplastics, small plastic particles contaminating the environment, is a subject of heated discussions today. It has been recognized that the microplastics are not inert, but instead they have an impact on all enviromnental compartments. There are studies describing the negative effects of microplastics, for example on fauna and flora or on human health, but the effects on soil quality have not been sufficiently described. The aim of this thesis was to assess the short and medium term effects that microplastics could have on the soil. In this work, a series of experiments were performed to elucidate the fate of microplastics in the soil. Changes in soil organic matter thermal properties, soil respiration, amount of water and soil aggregation depending on the incubation time were monitored. Three types of agricultural land (chernozem, cambisol and phaeozem), which were contaminated with different concentrations od PET and tyre rubber, were tested. The results confirmed the specific effects of microplastics on soil properties, which were observed in non-incubated samples (i.e. at the time of incubation 0 months), microplastics did not behave inertly in the soil and affected, for example, soil properties, texture and respiration.
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Pyrolytic graphite
Chýlková, Adéla ; Adam, Ondřej (referee) ; Němec, Karel (advisor)
The purpose of this bachelor thesis was to write a literature search summarizing knowledge about carbon-based materials and experimental determination of thermal expansion and thermal balance of samples of various types of graphite and evaluation of measured data. The research part of the work describes most of the currently known types of carbonaceous materials, with a more thorough study of pyrolytic graphite. The whole next chapter was devoted to a more thorough study of pyrolytic graphite. The second part of the thesis is focused on the experimental determination of thermal expansion and thermal balance on selected graphite samples (natural, expanded, pressed expanded and pyrolytic graphite). We used dilatometric analysis and thermogravimetry to solve this task. Finally, the measurement data were processed into graphs and relevant tables and conclusions were deduced.
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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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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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Analysis of biodegradable polymers in soils
Paluchová, Natálie ; Řezáčová, Veronika (referee) ; Kučerík, Jiří (advisor)
Currently, there is a growing interest in usage of biodegradable polymers, regardless of their possible risk of generation of residues. The methods that are used for determination of residues usually include pre-treatment and are expensive and time consuming. Therefore, this bachelor thesis focuses on the development and verification of analytical method that would identify and quantify of biodegradable polymer residues in soils to eliminate the problems arising from sample pre-treatment. Therefore, thermogravimetry, which appears to satisfy the above conditions, was used for the analysis. The area of polymer degradation in three types of soils during thermal oxidation and the effect of polymer on soil during the analysis was investigated. Poly(3 hydroxybutyrate) was chosen to be the representative biodegradable polymer and there were two approaches used to its detection and quatification. The methods were tested for 6 concentrations of poly(3–hydroxybutyrate) (0,1; 0,5; 1; 2; 3; 5 %). The first approach concentrated on the usage of polymer analysis in the presence of a blank (without contaminat), which was subtracted from the blank. Using this method, the temperature interval of polymer degradation and weigh loss changes in this interval were observed. The second method focused on a soil universal model, that allows the identification and quatification of samples when the blank is not present. The blank is simulated by 19 equations, that allow the identification of intervals, in which degradation of samples occurs and also it provides the possibility to determinate the type of the polymer. However, the principle component analysis indicated that the method is sensitive to the type of soil and therefore it needs adjustments. Samples were incubated for 4 months, to verify the sensitivity of the method, in case of partial or complete decomposition of samples by soil microorganisms,. Thereafter, the concentrations of poly(3-hydroxybutryrate) in soil determined by respirometry and thermogravimetry were compared. The results indicated that accelerated degradation caused by poly(3-hydroxybutrylate) or contamination of the sample with the surrounding atmosphere during respiration may have occurred. Residual poly(3–hydroxybutyrate) was thermogravimetrically verified and results were compared to respirometry. According to the results it can be observed that there was an interaction between the soil organic matter and biota or contamination of the sample with the surrounding atmosphere. The results revealed, that there is a possibility of determination of biodegradable polymers in soils by thermogravimetric analysis. There are good results using the blank method, but it is limited by the existence of a blank. The method that is using the soil universal model (without blank) has a great potential in the future, but adjustments still need to be done.
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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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