Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Molecular dynamics simulation of NH4-montmorillonite interlayer hydration: Structure, energetics, and dynamics
https://orcid.org/0000-0002-4509-9249
Abstract The interaction of ammonium ions (NH4 +) with clay is closely associated with many geochemistry, engineering, and environment issues. Molecular dynamics (MD) simulations were performed to investigate to the structure, energetics, and dynamics properties of ammonium-montmorillonite (NH4-Mt) at different hydration levels. The simulation results show that the layer spacing, immersion and hydration energy, atomic density, coordination number, self-diffusion coefficient and residence time of NH4-Mt vary with the water contents. The one-layer hydrate is the most energetically favorable at the water content of 5 H2O/uc but up to three-layer hydrate of NH4-Mt can potentially be formed at the high water content (13 H2O/uc). As the water content increases, some NH4 + ions which adsorbed in inner-sphere (IS) complexes at low hydration level can change to outer-sphere (OS) complexes, and further to random ions in a diffuse aqueous layer, with the interaction between NH4 + ions and basal surfaces becoming weaker. The H-bonding of N-Hn···Os, donated by hydrogen atoms of NH4 + to surface oxygen atoms, contributes to the adsorption of NH4 + ions besides the electrostatic attraction. NH4 + ions in inner-sphere complexes can reside above the hexagonal cavities longer and have more stable hydration shell at the low hydration level.
Graphical abstract Display Omitted
Highlights Monolayer hydrate is the most energetically favorable for NH4-Mt. H-bonds between NH4 + and Mt. contribute to the adsorption of NH4 +. Interaction between NH4 + and Mt. weakens as the water content increases. NH4 + in IS complexes reside above surface cavity longer at low water content.
Molecular dynamics simulation of NH4-montmorillonite interlayer hydration: Structure, energetics, and dynamics
https://orcid.org/0000-0002-4509-9249
Abstract The interaction of ammonium ions (NH4 +) with clay is closely associated with many geochemistry, engineering, and environment issues. Molecular dynamics (MD) simulations were performed to investigate to the structure, energetics, and dynamics properties of ammonium-montmorillonite (NH4-Mt) at different hydration levels. The simulation results show that the layer spacing, immersion and hydration energy, atomic density, coordination number, self-diffusion coefficient and residence time of NH4-Mt vary with the water contents. The one-layer hydrate is the most energetically favorable at the water content of 5 H2O/uc but up to three-layer hydrate of NH4-Mt can potentially be formed at the high water content (13 H2O/uc). As the water content increases, some NH4 + ions which adsorbed in inner-sphere (IS) complexes at low hydration level can change to outer-sphere (OS) complexes, and further to random ions in a diffuse aqueous layer, with the interaction between NH4 + ions and basal surfaces becoming weaker. The H-bonding of N-Hn···Os, donated by hydrogen atoms of NH4 + to surface oxygen atoms, contributes to the adsorption of NH4 + ions besides the electrostatic attraction. NH4 + ions in inner-sphere complexes can reside above the hexagonal cavities longer and have more stable hydration shell at the low hydration level.
Graphical abstract Display Omitted
Highlights Monolayer hydrate is the most energetically favorable for NH4-Mt. H-bonds between NH4 + and Mt. contribute to the adsorption of NH4 +. Interaction between NH4 + and Mt. weakens as the water content increases. NH4 + in IS complexes reside above surface cavity longer at low water content.
Molecular dynamics simulation of NH4-montmorillonite interlayer hydration: Structure, energetics, and dynamics
https://orcid.org/0000-0002-4509-9249
Abstract The interaction of ammonium ions (NH4 +) with clay is closely associated with many geochemistry, engineering, and environment issues. Molecular dynamics (MD) simulations were performed to investigate to the structure, energetics, and dynamics properties of ammonium-montmorillonite (NH4-Mt) at different hydration levels. The simulation results show that the layer spacing, immersion and hydration energy, atomic density, coordination number, self-diffusion coefficient and residence time of NH4-Mt vary with the water contents. The one-layer hydrate is the most energetically favorable at the water content of 5 H2O/uc but up to three-layer hydrate of NH4-Mt can potentially be formed at the high water content (13 H2O/uc). As the water content increases, some NH4 + ions which adsorbed in inner-sphere (IS) complexes at low hydration level can change to outer-sphere (OS) complexes, and further to random ions in a diffuse aqueous layer, with the interaction between NH4 + ions and basal surfaces becoming weaker. The H-bonding of N-Hn···Os, donated by hydrogen atoms of NH4 + to surface oxygen atoms, contributes to the adsorption of NH4 + ions besides the electrostatic attraction. NH4 + ions in inner-sphere complexes can reside above the hexagonal cavities longer and have more stable hydration shell at the low hydration level.
Graphical abstract Display Omitted
Highlights Monolayer hydrate is the most energetically favorable for NH4-Mt. H-bonds between NH4 + and Mt. contribute to the adsorption of NH4 +. Interaction between NH4 + and Mt. weakens as the water content increases. NH4 + in IS complexes reside above surface cavity longer at low water content.
Molecular dynamics simulation of NH4-montmorillonite interlayer hydration: Structure, energetics, and dynamics
Peng, Chenliang (Autor:in) / Wang, Guanshi (Autor:in) / Qin, Lei (Autor:in) / Luo, Sihai (Autor:in) / Min, Fanfei (Autor:in) / Zhu, Xia (Autor:in)
Applied Clay Science ; 195
03.05.2020
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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