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Effect of Na+, Ca2+ on the hydration properties of quartz surface: a molecular dynamics simulation study

Liu Chunfu, Min Fan-fei, Chen Jun, Liu Ling-yun, Ren Bao, Lv Kai

Physicochemical Problems of Mineral Processing

2022

Vol. 58, iss. 3

art. no. 147452

Effects of metal ions on the surface hydration of fine quartz are investigated by the theoretical methodologies. The hydration layer on the quartz surface is made up of three layers of water molecules, about 8-10 Å. The interaction energy of ions changes from -1.071 eV in water to -1.821 eV (Na+) and -1.896 eV (Ca2+) when ions are present. Metal ions improve the interaction of water molecules with the quartz surface, allowing more water molecules to enter the second and third hydration layers. In the presence of Na+, the diffusivity of water molecules is greater than in Ca2+ solutions. Increased interaction between water molecules and surfaces in the order Ca2+ > Na+ is consistent with metal ions’ propensity to hydrate.

Adsorption of methylamine cations on kaolinite basal surfaces : A DFT study

Chen Jun, Min Fan-fei, Liu Ling-yun, Jia Fei-fei

Physicochemical Problems of Mineral Processing

2020

Vol. 56, iss. 2

338--349

To explore the interaction of alkylamine surfactants with kaolinite, the density functional theory (DFT) method was used to calculate the single adsorption of different methylamine cation on kaolinite basal surfaces and the competitive adsorption of methylamine cation and water molecule on kaolinite basal surfaces, respectively. Different methylamine cations can adsorb on kaolinite basal surfaces by electrostatic interaction and hydrogen bonds, and the methylamine cations more easily adsorbed on kaolinite Si-O surface. In the case of competitive adsorption with water molecule, the methylamine cation is capable of flushing out the surrounding water molecule to get rid of its steric effect and stably adsorbing on kaolinite basal surfaces, and the adsorption state of the competitive adsorption system is more stable. The adsorption mechanism of methylamine cation on kaolinite basal surface should be the result of electrostatic interaction and hydrogen bonds, and the electrostatic interaction plays the main role.