scholarly journals First-Principles Density Functional Theory Characterisation of the Adsorption Complexes of H3AsO3 on Cobalt Ferrite (Fe2CoO4) Surfaces

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 195
Author(s):  
Eloise C. Lewis ◽  
Nelson Y. Dzade

The mobility of arsenic in aqueous systems can be controlled by its adsorption onto the surfaces of iron oxide minerals such as cobalt ferrite (Fe2CoO4). In this work, the adsorption energies, geometries, and vibrational properties of the most common form of As(III), arsenous acid (H3AsO3), onto the low-index (001), (110), and (111) surfaces of Fe2CoO4 have been investigated under dry and aqueous conditions using periodic density functional theory (DFT) calculations. The dry and hydroxylated surfaces of Fe2CoO4 steadily followed an order of increasing surface energy, and thus decreasing stability, of (001) < (111) < (110). Consequently, the favourability of H3AsO3 adsorption increased in the same order, favouring the least stable (110) surface. However, by analysis of the equilibrium crystal morphologies, this surface is unlikely to occur naturally. The surfaces were demonstrated to be further stabilised by the introduction of H2O/OH species, which coordinate the surface cations, providing a closer match to the bulk coordination of the surface species. The adsorption complexes of H3AsO3 on the hydroxylated Fe2CoO4 surfaces with the inclusion of explicit solvation molecules are found to be generally more stable than on the dry surfaces, demonstrating the importance of hydrogen-bonded interactions. Inner-sphere complexes involving bonds between the surface cations and molecular O atoms were strongly favoured over outer-sphere complexes. On the dry surfaces, deprotonated bidentate binuclear configurations were most thermodynamically favoured, whereas monodentate mononuclear configurations were typically more prevalent on the hydroxylated surfaces. Vibrational frequencies were analysed to ascertain the stabilities of the different adsorption complexes and to assign the As-O and O-H stretching modes of the adsorbed arsenic species. Our results highlight the importance of cobalt as a potential adsorbent for arsenic contaminated water treatment.

2021 ◽  
Author(s):  
Hung Minh Le ◽  
Mariano Guagliardo ◽  
Anne E. V. Gorden ◽  
Aurora Clark

Umbrella-sampling density functional theory molecular dynamics (DFT-MD) has been employed to study the full catalytic cycle of the allylic oxidation of cyclohexene using a Cu(II) 7-amino-6-((2-hydroxybenzylidene)amino)quinoxalin-2-ol complex in acetonitrile to...


2018 ◽  
Vol 20 (10) ◽  
pp. 7342-7350 ◽  
Author(s):  
Li Liu ◽  
Jing Zhang ◽  
Shaonan Dong ◽  
Fuping Zhang ◽  
Ye Wang ◽  
...  

The most representative pathway with Nm′ = 6 for the water-exchange reactions in Al(H2O)63+ is obtained by the “One-by-one” method.


2018 ◽  
Vol 20 (6) ◽  
pp. 977-987 ◽  
Author(s):  
Nelson Y. Dzade ◽  
Nora H. de Leeuw

Reactions occurring at ferric oxyhydroxide surfaces play an important role in controlling arsenic bioavailability and mobility in natural aqueous systems.


2019 ◽  
Vol 21 (44) ◽  
pp. 24478-24488 ◽  
Author(s):  
Martin Gleditzsch ◽  
Marc Jäger ◽  
Lukáš F. Pašteka ◽  
Armin Shayeghi ◽  
Rolf Schäfer

In depth analysis of doping effects on the geometric and electronic structure of tin clusters via electric beam deflection, numerical trajectory simulations and density functional theory.


2000 ◽  
Vol 98 (20) ◽  
pp. 1639-1658 ◽  
Author(s):  
Yuan He, Jurgen Grafenstein, Elfi Kraka,

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