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Chemical and thermal stability of humic complexes
Nováková, Tereza ; Pospíšilová, Ľubica (referee) ; Klučáková, Martina (advisor)
The aim of this diploma thesis was the study of relation between chemical and thermal stability of complexes of humic acids with heavy metals, namely nickel, cobalt and copper. Complexes were prepared with metal solutions of three different initial concentrations. Through UV-VIS spectrophotometry were determined adsorbed amounts of incorporated metal ions in the structure of humic acid; it was affirmed that amount of bounded metal ions increases with increasing initial concentration. Chemical stability was determined as an amount of released metal ions, two of extraction agents were used (solution of MgCl2 and HCl), total bounded amount was distribute into three different fractions; residual fraction, strongly bound fraction and mobile and ion-exchangeable fraction. Changes that occured in the structure of humic acids after complexation and extraction were investigated by FT-IR spectrometry. Thermo-oxidative stability was tested through thermogravimetric analysis (TGA) and differential scanning calorimetry. The results of this diploma thesis has showed comparision of complexes of two different humic acids. They have confirmed an impact of each metal ion on thermo-oxidative stability of humic acids. The relation between chemical and thermal stability was compared through correlation of data obtained by these methods.
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Supercritical Fluid Extraction: A Green Method for the Isolation of Valuable Substances from the Various Biological Matrices.
Topiař, Martin ; Sajfrtová, Marie ; Šolcová, Olga ; Hradecký, J. ; Hůrková, K. ; Hajšlová, J.
Supercritical fluid extraction (SFE) using carbon dioxide is a sophisticated technology suitable for isolation of un-polar, high value biological active substances from the various biological matrices. In this study, it was used for the extraction of Magnolia x pruhoniciana flowers and Japonochytrium marinum fungus. Results obtained from the SFE were compared with those from conventional extraction methods. A total number of 37 compounds were identified in the magnolia isolate, from which α-pinene (18 % of peak area), cymene (14 % of peak area), β-pinene (13 % of peak area) and humulene (6 % of peak area) were its main components. Yield of valuable free fatty acids DHA and EPA obtained by the SFE of Japonochytrium marinum was more than 1.5 times higher in comparison with organic liquid extraction using mixture of methanol and dichloromethane.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_22317120815262 - PDF
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Chemical and thermal stability of humic complexes
Nováková, Tereza ; Pospíšilová, Ľubica (referee) ; Klučáková, Martina (advisor)
The aim of this diploma thesis was the study of relation between chemical and thermal stability of complexes of humic acids with heavy metals, namely nickel, cobalt and copper. Complexes were prepared with metal solutions of three different initial concentrations. Through UV-VIS spectrophotometry were determined adsorbed amounts of incorporated metal ions in the structure of humic acid; it was affirmed that amount of bounded metal ions increases with increasing initial concentration. Chemical stability was determined as an amount of released metal ions, two of extraction agents were used (solution of MgCl2 and HCl), total bounded amount was distribute into three different fractions; residual fraction, strongly bound fraction and mobile and ion-exchangeable fraction. Changes that occured in the structure of humic acids after complexation and extraction were investigated by FT-IR spectrometry. Thermo-oxidative stability was tested through thermogravimetric analysis (TGA) and differential scanning calorimetry. The results of this diploma thesis has showed comparision of complexes of two different humic acids. They have confirmed an impact of each metal ion on thermo-oxidative stability of humic acids. The relation between chemical and thermal stability was compared through correlation of data obtained by these methods.
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