Degradation of organic extractants analyzed by quantum mechanical simulation methods

V rámci této disertační práce byly provedeny počítačové simulace na bázi metody funkcionálu hustoty za účelem teoretické analýzy chemické stability vybraných organických extraktantů typu DGA a BTBP. S použitím programů Gaussian a DMol3 byly vyhodnoceny deskriptory stability založené na elektronové a orbitalové struktuře. Konkrétně byla studována zejména stabilita vůči nepřímé radiolýze. Sada vypočítaných fyzikálně chemických vlastností vztahujících se ke stabilitě zahrnuje strukturu hraničních orbitalů, Fukuiho funkce, elektrostatické vlastnosti, nebo řády vazeb. Dále jsou prezentovány energetické profiIn this dissertation, computer simulations based on density functional theory (DFT) were performed in order to theoretically analyze the molecular stability of chosen DGA-type and BTBP-type organic extractants. Gaussian and DMol3 computational codes were used to evaluate the stability descriptors based on the electronic and orbital structure. In particular, the stability against indirect radiolysis was predominantly studied. The set of calculated physico-chemical properties related to stability includes structure of frontier orbitals, Fukui functions, electrostatic properties, and bond orders. In addition, energy profiles and reaction energy barriers of degradation reaction pathways are presented. These results will support the further development of the organic extractants, and of the whole sustainable nuclear fuel cycle

Simulation of UV/Vis Spectra of CyMe4BTBP and Some of its Degradation Products

Wet extraction and selective separation methods of actinide elements from highly active spent nuclear fuel constitutes a key step in the current waste reprocessing technologies. The quadridentate 6,6‘-bis(1,2,4-triazin-3-yl)-2,2‘-bipyridine ligands (BTBPs) form a very promising group of extraction agents investigated at recent. Radiation decay process of one of the BTBPs representatives, CyMe4BTBP, is indirectly analyzed by simulating the UV-Visible absorption spectra of the original compound and one proposed possible CyMe4BTBP and 1-octanol adduct and comparing the obtained courses with experimentally observed data. Ab-initio TDDFT approach using 6-31++G(d,p) basis set and wB97X, CAM-B3LYP, LC-wPBE functionals is applied. Partial agreement of the simulated and experimental data is found and discussed