Studium glycin nitrátových procesů pro přípravu nanomateriálů na bázi oxidů lanthanidů

Abstract

The dissertation thesis describes the study of glycine-nitrate processes of the preparation of nano-based lanthanide oxides. Firstly, several samples of Gd2O3, Sm2O3, and Er2O3 were synthesized using four amino acids (alanine, glycine, proline, and serine) to observe the effect of the amino acid used on the nature and morphology of the final product. The samples were prepared via thermal decomposition of a complex formed in situ from Ln(NO3)3·n H2O and selected amino acid. The resulting products were characterized by SEM/EDS, PS/PSD, FTIR, and XRPD analysis. It was found that the type of amino acid does not significantly affect the morphology, but only its crystallographic structure. To elucidate the reaction mechanism(s) of the glycine-nitrate combustion process for the synthesis of Gd2O3, Sm2O3, and Er2O3, a series of meso-stages samples of these syntheses were prepared and characterized. SEM/EDS analysis revealed a slow transformation of the lanthanide glycine nitrate gel to a more organized network morphology clearly associated with increasing calcination temperature. XRPD and FTIR analyzes revealed that the glycine-nitrate combustion process consists of at least two chemical processes. The first is a synproportionation process between (NVO3)-anions and -N-IIIH2 organic groups and the second is oxidative decarboxylation. Furthermore, selected samples of Gd2O3, Sm2O3, and Er2O3 were tested for antibacterial activity (against S. aureus, E. faecalis, E. coli, P. aeruginosa), for acute aquatic toxicity (C. vulgaris), and for lipoperoxidation and protein carbonylation. The lowest MICs were determined against E. coli and P. aeruginosa (5.6 mg·ml−1). The EC50 parameter againts C. vulgaris was determined to be 2.43 g·l-1 of nanocrystalline Sm2O3. Consequently, none of the Ln2O3 exhibits the ability of lipid peroxidation and protein carbonylation in a cell-free environment. Finally, it was found that the nanocrystalline oxides Gd2O3, Sm2O3, and Er2O3 are not photocatalytically active.