Hydration mechanisms of scheelite from adsorption isotherms and ab initio molecular dynamics simulations

Foucaud, Yann; Canevesi, Rafael Luan Sehn; Celzard, Alain; Fierro, Vanessa; Badawi, Michaël

doi:10.1016/j.apsusc.2021.150137

Cited by 26 publications

(7 citation statements)

References 92 publications

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“…The adsorption energy of a single water on the (001) surface is -83.80 kJ/mol, this is in good agreement with the typical values for the adsorption of the water molecules on metals/minerals surfaces, e.g. -89 kJ/mol for calcite (Rahaman et al, 2008), -80 kJ/mol for the (001) surface of scheelite (Foucaud et al, 2021b), −91.0 kJ/mol and−94.2 kJ/mol for the adsorption on magnesium and calcium cations on dolomite surface, respectively (Semmeq et al, 2021). This indicates that the fluorapatite has a strong affinity for water molecule, so the surface of natural fluorapatite is hydrophilic.…”

Section: Computational Modelssupporting

confidence: 85%

“…An et al (2021) found that the essence of synergetic mechanism of oleic acid-dodecane was that they formed a relatively ordered "supramolecular structure" on the low rank coal surface. Foucaud et al (2021b) indicated through DFT calculation that during the hydration process of scheelite, Ca 2+ ions on the mineral surface can adsorb water molecules. Mkhonto et al (2006) demonstrated Ca 2+ ions play a key role in the adsorption process of reagents and fluorapatite surface.…”

Section: Introductionmentioning

confidence: 99%

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DFT study of coadsorption of fatty acid and kerosene on fluorapatite (001) surface

Du¹,

Li²,

Zhang³

2023

Physicochem. Probl. Miner. Process.

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The adsorption of fatty acid, kerosene and fatty acid-kerosene on fluorapatite (001) surface were investigated by density functional theory (DFT) calculations. The results showed that the single fatty acid could form stable chemisorption on fluorapatite (001) surface by the O of fatty acids bonding with Ca1 site. The single kerosene could not be stably adsorbed on fluorapatite (001) surface because the H of kerosene did not form hydrogen bond with the O of PO43- on (001) surface (Osurf). For the coadsorption conformation, the chemisorption of fatty acid-kerosene on fluorapatite (001) surface was contributed by the interaction between O of fatty acids and Ca1, the H of kerosene did not bond with the Osurf, but the carbon chain length of kerosene has a large influence on the coadsorption. Compared with the coadsorption of fatty acid-decane, the adsorption of butyric acid-tetradecane and octanoic acid-tetradecane on fluorapatite (001) surface have greater adsorption energies and overlapping region of DOS between O 2p and Ca 4d, indicating that there is a synergistic effect between fatty acid and tetradecane. Meanwhile, the collaborative effects exist between the molecules of fatty acids. The interpenetrating adsorption of fatty acid and kerosene on the fluorapatite surface could improve the adsorption strength and density. The flotation test further confirmed that the single kerosene could not collect fluorapatite, but it could be collected by the single fatty acid. Besides, the synergistic effect between fatty acid and kerosene could increase the flotation recovery of fluorapatite.

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Section: Computational Modelssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

DFT study of coadsorption of fatty acid and kerosene on fluorapatite (001) surface

Du¹,

Li²,

Zhang³

2023

Physicochem. Probl. Miner. Process.

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“…Besides, when adsorption models were used, we systematically applied the dual-site Freundlich–Langmuir (DSFL) equation to fit the experimental models with good accuracy. This model combines the robustness of the Langmuir isotherm, with a better description given by the Freundlich isotherm for high equilibrium pressures, and considers the possible existence of multiple adsorption sites . The general equation for the DSFL adsorption model is as follows: n = a 1 · b 1 · p c 1 1 + b 1 · p c 1 + a 2 · b 2 · p c 2 1 + b 2 · p c 2 where n is the adsorbed amount (mol·kg –1 ), p (bar) is the equilibrium pressure (bar), a (mol·kg –1 ) is the maximum uptake, b (bar –c ) is the affinity constant between the adsorbent and the adsorbate, and c (dimensionless) is the heterogeneity exponent.…”

Section: Methodsmentioning

confidence: 99%

“…This model combines the robustness of the Langmuir isotherm, 64 with a better description given by the Freundlich isotherm 65 for high equilibrium pressures, and considers the possible existence of multiple adsorption sites. 66 The general equation for the DSFL adsorption model is as follows:…”

Section: Calculation Of the Isosteric Enthalpy Of Adsorptionmentioning

confidence: 99%

“…For this point, the calculated isosteric enthalpy of adsorption is approximate −90 kJ•mol −1 , which is consistent with the values reported for the adsorption of molecules on polar mineral surfaces. 66,95,96 The isosteric enthalpy of adsorption decreases significantly with the adsorbed volume, which corresponds to the formation of several layers (Figure 6). The second layer presents an average ΔH ads between −55 kJ•mol −1 (from models) and − 47 kJ•mol −1 (from experimental points) and the third layer has an average ΔH ads between −50 kJ•mol −1 (from models) and − 46 kJ•mol −1 (from experimental points).…”

Section: Isosteric Enthalpy Of Adsorptionmentioning

confidence: 99%

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Hydration Mechanisms of Tungsten Trioxide Revealed by Water Adsorption Isotherms and First-Principles Molecular Dynamics Simulations

Foucaud

Jannet

Caramori³

et al. 2023

J. Phys. Chem. C

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WO3 is one of the most interesting materials for photocatalysis due to its optical absorption in UV–vis, good charge carrier transport, and stability against photocorrosion. A detailed knowledge of the hydration state of WO3 is indispensable to gain more precise mechanistic insights into its photocatalytic activity. To the best of our knowledge, the hydration process of WO3 has been scarcely studied so far and only from a theoretical point of view, mostly by means of static density functional theory calculations. Here, we use manometric gas sorption experiments combined with extensive ab initio molecular dynamics simulations to investigate the hydration mechanisms of WO3 at room temperature. We demonstrate that water adsorbs molecularly in a two-step mechanism: the first water sublayer interacts with the under-coordinated surface tungsten atoms through electrostatic interactions, and, in a second step, a full layer is formed through hydrogen bonds established with the pre-adsorbed water molecules and with the under-coordinated surface oxygen atoms. The computed value of −90 kJ·mol–1 for the isosteric enthalpy of adsorption of the first water molecules is in excellent agreement with the experimental value estimated using the Clausius–Clapeyron approach from the experimental adsorption isotherms. The isosteric enthalpy of adsorption steadily decreases in absolute value when the surface coverage is increased to tend toward the enthalpy of condensation of water after three adsorption layers.

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Flotation separation depressants for scheelite and calcium-bearing minerals: A review

Wang,

Feng,

Chen

2023

Int J Miner Metall Mater

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Hydration mechanisms of scheelite from adsorption isotherms and ab initio molecular dynamics simulations

Cited by 26 publications

References 92 publications

DFT study of coadsorption of fatty acid and kerosene on fluorapatite (001) surface

DFT study of coadsorption of fatty acid and kerosene on fluorapatite (001) surface

Hydration Mechanisms of Tungsten Trioxide Revealed by Water Adsorption Isotherms and First-Principles Molecular Dynamics Simulations

Flotation separation depressants for scheelite and calcium-bearing minerals: A review

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