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Production and characterization of regenerated humic acids
Uhrová, Anna ; Daniela,, Šmejkalová (oponent) ; Kučerík, Jiří (vedoucí práce)
A fraction of South Moravian lignite mined in Mír Mikulčice, Lignit Ltd. was modified by two oxidizers (HNO3, H2O2) and two “amphiphilic-like” agents (acetic and citric acids, respectively). Alkali extraction was used to obtain both humic acids from non-treated lignite and so-called regenerated humic acids. Several methods were used for characterization of obtained samples. Based on the results of elemental analysis, the C/O and C/H ratios were calculated and completed by FTIR measurement; that provided the information on aromaticity/aliphaticity of the samples and degree of carbon oxidation. To assess the distribution of molecular dimensions of humic aggregates the High Performance Size Exclusion Chromatography was used. To elucidate the mechanisms of processes occurring in the surface layer of water solutions the surface tension measurement was carried out. Obtained data were fitted with Szyszkowski equation to get parameters characterizing the surfactant efficiency of humic acids and indicating the nature of humic molecules responsible for their surface activity. Finally, the Pearson correlation was used to search the interrelationships among results obtained by the above-mentioned techniques.
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Remediation Potential of Humic Acids
Uhrová, Anna ; Lehocký,, Marián (oponent) ; Pospíšilová,, Lubica (oponent) ; Kučerík, Jiří (vedoucí práce)
In this work, we tested the modified lignite humic acids for their remediation capability of agricultural soils. Prior to the extraction of humic acids, the parental raw lignite was modified by ten organic acids. The pre-treatment was aimed to simulate similar processes that occur in rhizosphere, i.e. small-chain organic acids induce the reconformation of soil organic matter thereby releasing biologically active aggregates/molecules promoting the plant growth. In the first step, the produced modified humic acids (MHA) were characterised for their physico-chemical properties and molecular structure of by using elemental analysis (EA), Fourier-transformed infrared (FTIR) spectroscopy, high-pressure size exclusion chromatography (HPSEC), surface tension measurement and gas chromatography-mass spectrometry (GC-MS) analysis. In the second step, the parameters of biological activity were obtained from experiments oriented to both higher plants and remediation of microbiological activity in used soil. The biological activity towards higher plants was conducted on maize seeds and represented by total mass and length increments of roots, root division and sugars and protein contents. The influence on used soil was determined by laboratory soil incubation (CO2 production) and soil water repellency measurement (contact angle). All results were subjected to statistical analysis using Pearson´s correlation coefficient to find relationship between physico-chemical properties and biological activity of studied HAs samples. The results showed correlations between biological activity and physico-chemical properties of humic acids. On the contrary, the surface properties did not show any correlations with physical-chemical properties of studied HAs. The most efficient modifier in terms of biological activity was 20% formic acid and the less efficient was 20% propionic acid.
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Remediation Potential of Humic Acids
Uhrová, Anna ; Lehocký,, Marián (oponent) ; Pospíšilová,, Lubica (oponent) ; Kučerík, Jiří (vedoucí práce)
In this work, we tested the modified lignite humic acids for their remediation capability of agricultural soils. Prior to the extraction of humic acids, the parental raw lignite was modified by ten organic acids. The pre-treatment was aimed to simulate similar processes that occur in rhizosphere, i.e. small-chain organic acids induce the reconformation of soil organic matter thereby releasing biologically active aggregates/molecules promoting the plant growth. In the first step, the produced modified humic acids (MHA) were characterised for their physico-chemical properties and molecular structure of by using elemental analysis (EA), Fourier-transformed infrared (FTIR) spectroscopy, high-pressure size exclusion chromatography (HPSEC), surface tension measurement and gas chromatography-mass spectrometry (GC-MS) analysis. In the second step, the parameters of biological activity were obtained from experiments oriented to both higher plants and remediation of microbiological activity in used soil. The biological activity towards higher plants was conducted on maize seeds and represented by total mass and length increments of roots, root division and sugars and protein contents. The influence on used soil was determined by laboratory soil incubation (CO2 production) and soil water repellency measurement (contact angle). All results were subjected to statistical analysis using Pearson´s correlation coefficient to find relationship between physico-chemical properties and biological activity of studied HAs samples. The results showed correlations between biological activity and physico-chemical properties of humic acids. On the contrary, the surface properties did not show any correlations with physical-chemical properties of studied HAs. The most efficient modifier in terms of biological activity was 20% formic acid and the less efficient was 20% propionic acid.
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Production and characterization of regenerated humic acids
Uhrová, Anna ; Daniela,, Šmejkalová (oponent) ; Kučerík, Jiří (vedoucí práce)
A fraction of South Moravian lignite mined in Mír Mikulčice, Lignit Ltd. was modified by two oxidizers (HNO3, H2O2) and two “amphiphilic-like” agents (acetic and citric acids, respectively). Alkali extraction was used to obtain both humic acids from non-treated lignite and so-called regenerated humic acids. Several methods were used for characterization of obtained samples. Based on the results of elemental analysis, the C/O and C/H ratios were calculated and completed by FTIR measurement; that provided the information on aromaticity/aliphaticity of the samples and degree of carbon oxidation. To assess the distribution of molecular dimensions of humic aggregates the High Performance Size Exclusion Chromatography was used. To elucidate the mechanisms of processes occurring in the surface layer of water solutions the surface tension measurement was carried out. Obtained data were fitted with Szyszkowski equation to get parameters characterizing the surfactant efficiency of humic acids and indicating the nature of humic molecules responsible for their surface activity. Finally, the Pearson correlation was used to search the interrelationships among results obtained by the above-mentioned techniques.
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