Δημοσιεύσεις

Project Acronym: THERMOCLAY2
Title: Thermo-physical, configuration and dynamic properties of clay/kerogens systems
Affiliation: national center for scientific research demokritos
Pi: Ioannis Economou
Research Field: chemical sciences and materials

Molecular Dynamics Simulation of Water-Based Fracturing Fluids in Kaolinite Slit Pores
by Papavasileiou, Konstantinos D., Michalis, Vasileios K., Peristeras, Loukas D., Vasileiadis, Manolis, Striolo, Alberto and Economou, Ioannis G.
Abstract:
The adsorption behavior inside kaolinite mesopores of aqueous solutions of various salts and additives is investigated using Molecular Dynamics simulations. In particular, we examine the various combinations of water + salt, water + additive, and water + salt + additive mixtures, where the salts are NaCl, CsCl, SrCl2, and RaCl2 and the additives are methanol and citric acid. Citric acid is modeled in two forms, namely, fully protonated (H3A) and fully deprotonated (A3–), the latter being prevalent in neutral pH conditions, in accordance with the kaolinite structure employed. The force fields used for the individual system components include CLAYFF for the kaolinite mesopores, SPC/E for water, parameters optimized for the SPC/E water model based on hydration free energies (HFE) for ions, and general Amber force field (GAFF) for the additives. The spatial distributions along the kaolinite pore are delineated and reveal the preferential adsorption behavior of the various species with respect to the gibbsite and siloxane surface, as well as the effect on this behavior of the interactions between the various species. Furthermore, we examine the hydrogen bonds formed between the kaolinite surfaces and water molecules as well as the additives. For the case of citric acid, which tends to aggregate, a cluster analysis is also carried out, in order to examine the effect of the various ions on the cluster formation. Finally, through the calculation of lateral diffusion coefficients and mean residence times, we provide insights on the mobility of the various species inside the kaolinite mesopores.
Reference:
Molecular Dynamics Simulation of Water-Based Fracturing Fluids in Kaolinite Slit Pores (Papavasileiou, Konstantinos D., Michalis, Vasileios K., Peristeras, Loukas D., Vasileiadis, Manolis, Striolo, Alberto and Economou, Ioannis G.), In The Journal of Physical Chemistry C, volume 122, 2018.
Bibtex Entry:
@article{doi:10.1021-acs.jpcc.8b03552,
 author = {Papavasileiou, Konstantinos D. and Michalis, Vasileios K. and Peristeras, Loukas D. and Vasileiadis, Manolis and Striolo, Alberto and Economou, Ioannis G.},
 title = {Molecular Dynamics Simulation of Water-Based Fracturing Fluids in Kaolinite Slit Pores},
 journal = {The Journal of Physical Chemistry C},
 volume = {122},
 number = {30},
 pages = {17170-17183},
 year = {2018},
 bibyear = {2018},
 doi = {10.1021/acs.jpcc.8b03552},
 url = {https://doi.org/10.1021/acs.jpcc.8b03552},
 eprint = {https://doi.org/10.1021/acs.jpcc.8b03552},
 abstract = { The adsorption behavior inside kaolinite mesopores of aqueous solutions of various salts and additives is investigated using Molecular Dynamics simulations. In particular, we examine the various combinations of water + salt, water + additive, and water + salt + additive mixtures, where the salts are NaCl, CsCl, SrCl2, and RaCl2 and the additives are methanol and citric acid. Citric acid is modeled in two forms, namely, fully protonated (H3A) and fully deprotonated (A3–), the latter being prevalent in neutral pH conditions, in accordance with the kaolinite structure employed. The force fields used for the individual system components include CLAYFF for the kaolinite mesopores, SPC/E for water, parameters optimized for the SPC/E water model based on hydration free energies (HFE) for ions, and general Amber force field (GAFF) for the additives. The spatial distributions along the kaolinite pore are delineated and reveal the preferential adsorption behavior of the various species with respect to the gibbsite and siloxane surface, as well as the effect on this behavior of the interactions between the various species. Furthermore, we examine the hydrogen bonds formed between the kaolinite surfaces and water molecules as well as the additives. For the case of citric acid, which tends to aggregate, a cluster analysis is also carried out, in order to examine the effect of the various ions on the cluster formation. Finally, through the calculation of lateral diffusion coefficients and mean residence times, we provide insights on the mobility of the various species inside the kaolinite mesopores. },
}