TY - JOUR

T1 - Structure of bound water layer on montmorillonite surface: The role of trans- and cis- vacant sites

AU - Kasprzhitskii, Anton

AU - Kruglikov, Alexander

AU - Ermolov, Yakov

AU - Yavna, Victor

AU - Pleshko, Mikhail

AU - Lazorenko, Georgy

N1 - The research is carried out using the equipment of the shared research facilities of HPC computing resources at Lomonosov Moscow State University. The analysis of the energies of adsorbed water layer and charge change in the system was supported by the Russian Science Foundation (Grant No. 21-79-20005 ). The structure and bonding analysis of adsorbed water layer was funded by a grant Russian Science Foundation No. 19-79-10266 , https://rscf.ru/project/19-79-10266/. The models for the calculations were obtained with the support by a grant from the President of the Russian Federation for state support of young Russian scientists - candidates of science (project No. MK-578.2022.4). The analysis of partial density of states is supported by the grant from the Ministry of Science and Higher Education of Russian Federation (Agreement No. 075-15-2022-1111).

PY - 2024/1/1

Y1 - 2024/1/1

N2 - Bound water on the surface of clay minerals determines the nature of a wide class of phenomena, from the diffusion of interlayer cations to synthesizing prebiotic macromolecules during the early Earth. However, the nature of forming the bound water layer's spatial structure and properties has yet to be fully investigated. Many factors, including peculiarities of structural charge distribution, surface adsorption centers, and OH-groups of the octahedral sheet of the clay minerals, can affect it in natural clays. In this work the role of hydroxyl ligands and isomorphic substitutions of the octahedral sheet in trans- and cis- vacant sites in the formation of the bound water layer structure on the basal surface of montmorillonite was studied by the Density Functional Theory. It was found out that in the case of single isomorphic substitution in the octahedral sheet OH-groups in the cis-vacant sites provide higher adsorption energy of water molecules on the basal surface as compared to OH-groups in the trans-vacant sites. The double isomorphic substitution in the octahedral sheet creates a mutual enhancement effect due to the difference in the structural arrangement of the OH-groups. This leads to an increase in the interaction with adsorbed water molecules. The maximum increase in adsorption energy is observed for the case with isomorphic substitutions of Mg-cis and Fe-trans in the octahedral sheet. The results of the theoretical study contribute to explaining the experimental data available in the literature.

AB - Bound water on the surface of clay minerals determines the nature of a wide class of phenomena, from the diffusion of interlayer cations to synthesizing prebiotic macromolecules during the early Earth. However, the nature of forming the bound water layer's spatial structure and properties has yet to be fully investigated. Many factors, including peculiarities of structural charge distribution, surface adsorption centers, and OH-groups of the octahedral sheet of the clay minerals, can affect it in natural clays. In this work the role of hydroxyl ligands and isomorphic substitutions of the octahedral sheet in trans- and cis- vacant sites in the formation of the bound water layer structure on the basal surface of montmorillonite was studied by the Density Functional Theory. It was found out that in the case of single isomorphic substitution in the octahedral sheet OH-groups in the cis-vacant sites provide higher adsorption energy of water molecules on the basal surface as compared to OH-groups in the trans-vacant sites. The double isomorphic substitution in the octahedral sheet creates a mutual enhancement effect due to the difference in the structural arrangement of the OH-groups. This leads to an increase in the interaction with adsorbed water molecules. The maximum increase in adsorption energy is observed for the case with isomorphic substitutions of Mg-cis and Fe-trans in the octahedral sheet. The results of the theoretical study contribute to explaining the experimental data available in the literature.

KW - Bound water

KW - Cis-vacant site

KW - Clay minerals

KW - DFT

KW - Montmorillonite

KW - Trans-vacant site

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85172736309&origin=inward&txGid=a4771c45c4cd3d288d8c9b011cec877a

UR - https://www.mendeley.com/catalogue/0ee9c566-9484-3adb-8743-bbfe1d8eb473/

U2 - 10.1016/j.apsusc.2023.158565

DO - 10.1016/j.apsusc.2023.158565

M3 - Article

VL - 642

JO - Applied Surface Science

JF - Applied Surface Science

SN - 0169-4332

M1 - 158565

ER -