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Wyszukujesz frazę "computational calculations" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
Substitution mechanism of rare earths at fluorapatite characteristic sites : experimental and computational calculations
Autorzy:
Xie, Jun
Powiązania:
https://bibliotekanauki.pl/articles/24085936.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rare earth
phosphorite
doping
electronic properties
computational calculations
Opis:
Rare earths (REs) containing phosphate rock is a potential REs resource. The unclear occurrence mechanism of REs in phosphorite limits its further development and utilization. Fluorapatite (FAP) is the main REs-bearing target mineral in phosphorite, the microscopic mechanism of REs entering FAP still needs to be further studied from the electronic scale. In this paper, the doping mechanism of REs in FAP was studied by experiment combined with GGA+U calculation. The XRD, SEM, and FT-IR characterization results of hydrothermal synthesis products showed that REs (La, Ce, Nd, and Y) entered FAP crystal, and one of every 20 Ca atoms was replaced by a REs atom. The GGA+U calculation indicated that La-O/F, Ce-O/F, Nd-O/F, and Y-O/F were ionic bonds in general, and the bonding strength of La-O/F, Ce-O/F, Nd-O/F, and Y-O/F increased gradually with atomic number. The substitution difference of La, Ce, Nd, and Y was mainly caused by the gain and loss of electrons in f and d orbitals. The substitution mechanism of REs at the characteristic sites of Fap was studied, which provided a theoretical reference for the selective recovery of REs from phosphorus blocks.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 2; art. no. 163418
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of chlorine substitution on the adsorption of chlorophenols on HDTMA-modified halloysite in aqueous solutions
Autorzy:
Szczepanik, Beata
Kołbus, Anna
Słomkiewicz, Piotr
Czaplicka, Marianna
Powiązania:
https://bibliotekanauki.pl/articles/27311560.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
adsorption
mechanism
chlorophenols
HDTMA-halloysite adsorbent
computational calculations
adsorpcja
mechanizm
chlorofenol
kalkulacja
haloizyt
Opis:
This article focuses on discussing the adsorption process of phenol and its chloro-derivatives on the HDTMA-modified halloysite. Optimized chemical structures of phenol, 2-, 3-, 4-chlorophenol, 2,4-dichloro-, and 2,4,6-trichlorophenol were obtained with computational calculation (the Scigress program). Charge distributions and the hypothetical structure of the system HDTMA-modified halloysite are among their key features. The above-mentioned calculations are applied in order to explain adsorption mechanism details of chlorophenols on the HDTMA-modified halloysite in aqueous solutions. The results of electron density distribution and solvent accessible surface area calculations for phenol and chlorophenols molecules illustrate the impact of chlorine substitution position in a phenol molecule, both on the mechanism and the kinetics of their adsorption in aqueous solutions. Experimental adsorption data were sufficiently represented using the Langmuir multi-center adsorption model for all adsorbates. In addition, the relations between adsorption isotherm parameters and the adsorbate properties were discussed. This study also targets at explaining the role of meta position as a chlorine substituent for mono-chloro derivatives. Given the above findings, two possible mechanisms were utilized as regards chlorophenol adsorption on the HDTMA-modified halloysite, i.e., electrostatic and partition interactions when the chlorophenols exist in a molecular form.
Źródło:
Archives of Environmental Protection; 2023, 49, 2; 66--75
2083-4772
2083-4810
Pojawia się w:
Archives of Environmental Protection
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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