Ab Initio Molecular Dynamics Study of a Monomolecular Water Layer on Octahedral and Tetrahedral Kaolinite Surfaces

Abstract

The structure and dynamics of a monomolecular water layer on the octahedral and tetrahedral surfaces of the kaolinite layer have been investigated using short-time ab initio molecular dynamics. The arrangement and the structure of the water layer differ significantly on both surfaces. On the octahedral side the water layer forms relatively strong hydrogen bonds with the surface hydroxyl groups. This interaction significantly influences the layout of the water molecules in this case. On the other hand, the water molecules on the tetrahedral surface have the tendency to aggregate, forming hydrogen bonds among themselves. Only weak hydrogen bonds with the basal oxygen atoms of the tetrahedral surface are formed. Thus, the octahedral and tetrahedral surfaces of the kaolinite layer are of different chemical nature and can be considered as hydrophilic and hydrophobic, respectively.

A molecular dynamics investigation into the adsorption behavior inside {001} kaolinite and {1014} calcite nano-scale channels: the case with confined hydrocarbon liquid, acid gases, and water

“…2B, b). The results for z-density of oxygen atoms over {001} octahedral kaolinite surface are in good agreement with previous computational reports (Feibelman 2013;Tunega et al 2004). The adsorption profiles (Fig.…”

“…Nevertheless, those researches pinpoint to the complexity of wetting behavior existent in different types of minerals. For instance, octahedral and tetrahedral surfaces of {001} kaolinite are discovered with hydrophilic and hydrophobic characteristics, respectively (Ni and Choi 2012;Š olc et al 2011;Tunega et al 2004). In addition, hydroxylated surfaces of mineral surfaces can reportedly be different in wetting properties (Chai et al 2009;Liascukiene et al 2014).…”

Structure and bonding nature of [PbCl]+ adsorption on the kaolinite(0 0 1) surface in aqueous system

“…Three types of hydrogen bonds formed: Surface oxygen "O l " with hydrogen of aqua ligands ("O l · · ·H w "), ligand of chlorine with hydrogen of surface "O u H" groups ("Cl· · ·H u ") and oxygen of aqua ligands with hydrogen of "O u H" groups ("O w · · ·H u "). Surface "O l " exhibited strong attraction to hydrogen in aqua ligands of Pb(II) with short "O l · · ·H w " bond lengths of 1.61-1.71Å (Table 2), consistent with the corresponding average value of 1.621Å in an ab initio molecular dynamics study [31]. However, repulsion was the dominant interaction between surface "O u H" groups and the aqua ligands, where hydrogen bond of "O w · · ·H u " was relatively weak (values did not show in Table 2) and was less of a factor for the stability of complex.…”

Atomic scale structures of interfaces between kaolinite edges and water

“…For kaolinite, many simulation studies have been conducted to investigate the chemistry of basal surfaces. With FPMD (first principles molecular dynamics), Tunega et al (2004aTunega et al ( , 2004b) studied the adsorption of water and phenoxyacetic acid herbicides on basal surfaces and they quantified the H-bonding structures. Vasconcelos et al (2007) applied classical molecular dynamics to investigate the adsorption of metal cations on basal surfaces of kaolinite.…”