Interfacial water structure and the wetting of mineral surfaces

Abstract

Advanced tools, including atomic force microscopy (AFM), sum frequency vibrational spectroscopy (SFVS), and molecular dynamics simulations (MDS), are being used to describe interfacial water structure and to contrast the structure of water at a hydrophilic mineral surface with that at a hydrophobic mineral surface. Specifically, this contrast is revealed from interfacial water features based on the extent of H-bonding, dipole orientation, exclusion zone thickness, and residence time. Progress in our understanding of interfacial water structure and wetting phenomena is reported for different mineral classes including sulfides, oxides/hydroxides, layered silicates (phyllosilicates), and salt-type minerals, including both semi-soluble and soluble salts.

Probing the Interaction Mechanism between Benzohydroxamic Acid and Mineral Surface in the Presence of Pb2+ Ions by AFM Force Measurements and First-Principles Calculations

“…To better unveil the interaction mechanism, the first-principles density functional theory (DFT) calculation was employed to validate the AFM force measurement results. In an aqueous solution, a hydration layer was formed by the adsorption of water molecules on oxide and silicate mineral surfaces, , which is of fundamental importance for mineral surfaces interacting with flotation reagents, ,,,− solid particles , and air bubbles. − In our DFT simulation model, a hydration layer containing 50 water molecules was first placed onto the spodumene (110) surface for running MD relaxation for 2 ns and then only 12 water molecules were retained. After geometry optimization, the dissociation–adsorption of water on the spodumene (110) surface was energetically favorable, resulting in abundant free OH – functional groups.…”

Effects of the Goethite Surface Hydration Microstructure on the Adsorption of the Collectors Dodecylamine and Sodium Oleate

“…Iron oxide minerals have strong hydrophilicity, and their surface can be reconstructed by water molecules . Miller et al found that the experimental contact angles of goethite are 0 at both pH 5.5 and 10.6, while those of hematite are 48 and 0° at pH 5.5 and 10.6, respectively, which indicate that goethite is more hydrophilic than hematite. De Leeuw and Cooper analyzed the hydroxylation behavior of water molecules on the surface of structured-Fe­(OH) 2 , goethite, and hematite through surface energy; they pointed out that the dissociative adsorption of water molecules on the surface of goethite released more hydration energy than that of hematite, and water molecules showed a tendency for molecular adsorption only on the goethite (010) surface.…”

Density Functional Theory Study of Water Molecule Adsorption on the α-Quartz (001) Surface with and without the Presence of Na+, Mg2+, and Ca2+

“…This process plays an important role in colloidal chemistry, 1 wastewater treatment, 2 and mineral processing. 3 For instance, with highly muddied coal slurry containing a large amount of hydrophilic quartz and clay mineral particles, slurry’s sedimentation and dewatering becomes more difficult owing to mineral hydration. 4,5 The reason for this is the strong hydration repulsion and stereohindrance effect being produced and making the dispersion system stable.…”

“…Water molecules are adsorbed on the hydrophilic mineral’s surface (e.g., quartz and clay minerals) and arranged in a certain order which is referred to as mineral hydration. This process plays an important role in colloidal chemistry, wastewater treatment, and mineral processing . For instance, with highly muddied coal slurry containing a large amount of hydrophilic quartz and clay mineral particles, slurry’s sedimentation and dewatering becomes more difficult owing to mineral hydration. , The reason for this is the strong hydration repulsion and stereohindrance effect being produced and making the dispersion system stable. − For this reason, the mineral surface hydration characteristics have emerged as the critical aspect of solving problems dealing with how to treat coal slurry.…”