Wetting Behavior of Nanoscale Thin Films of Selected Organic Compounds and Water on Model Basal Surfaces of Kaolinite

Abstract

Molecular dynamics (MD) simulation and density functional theory (DFT) were applied to study the wetting behavior of nanoscale thin films of n-heptane, toluene, pyridine, and water at different thicknesses on the two model basal surfaces of kaolinite at room temperature. Despite the hydrophilicity of the basal surfaces, water exhibited the lowest affinity for them, but was statistically comparable to that of nheptane, as quantified by the corresponding calculated monomolecular layer works of adhesion. The results are consistent with the simulations in which water molecules in monomolecular layer originally sandwiched between a monomolecular layer of aromatic compounds and the two basal surfaces departed from the surfaces, while the aromatic molecules migrated to the surfaces. However, such behavior was not observed in the cases in which water thin films contained multiple molecular layers of water. Interestingly, the corresponding calculated multimolecular layer works of adhesion of water were the highest among the compounds of interest. Analysis of the simulation data on both basal surfaces suggests that such observation is attributed to the water/water long-range charge−charge (69%, averaged over the two basal surfaces) and shortrange hydrogen-bond (31%) interactions. Here, interfacial hydrogen bonds play a relatively minor role in the wetting behavior of water.

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

“…5) may lead us to an important finding that adsorption layer of water molecules over calcite surface (in S2 systems) looks more ordered than its adsorption layer counterpart over the kaolinite surface, albeit kaolinite's hydrophilicity. The accumulation of hydrocarbon molecules in the middle of simulation box can be a result of hydrophilicity of {001} octahedral kaolinite surface and this behavior is in agreement with previous results (Ni and Choi 2012). To obtain accurate results, the system should have reached equilibrium prior to sampling the simulation box.…”

“…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).…”

Novel Synthesis of Choline-Based Amino Acid Ionic Liquids and Their Applications for Separating Asphalt from Carbonate Rocks

“…The more negative the interaction energy is, the stronger the adsorption is. The detailed procedures can be found elsewhere [28,32].…”

Effects of the N, O, and S heteroatoms on the adsorption and desorption of asphaltenes on silica surface: A molecular dynamics simulation

“…Particularly, the hydrogen bonds formed between the water molecules and the hydroxyl groups on the silica surface contribute to the adsorption of water molecules. The hydrogen bonding network within these water molecules also facilitate the affinity and stabilization of the water layer on the silica surface [46].…”