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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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