Electronic simulations of alanine and water coadsorption over Defect-free and Sulfur-depleted sphalerite surfaces

Emerging Trends of Computational Chemistry and Molecular Modeling in Froth Flotation: A Review

“…A DFT study on the adsorption of alanine on the ZnS surface further suggested that solvated alanine cannot be chemically adsorbed on the defect-free ZnS surface, while surface sulfur vacancy prompts alanine adsorption on the ZnS surface through the formation of monodentate bond with the undercoordinated Zn atoms around the vacancy site. 51 Alteration of the adsorption modes, from chemisorption in the vacuum to physisorption in the presence of water molecules, was also reported in the case of sodium dimethyl dithiocarbamate (SDD) and butyl xanthate (BX) collectors adsorption on the sphalerite (110) surface. 368 All of these examples emphasize the need to consider water molecules to reflect true interactions in modeling flotation systems.…”

“…Despite the intriguing findings, one should be aware that excluding solvation and surface complexation in an aqueous environment could cause uncertainties in the results, thereby compromising their practical applicability. 50,51 Sutton et al 171 ranked the interactions of 20 bis-phosphinate ligands toward calcite (104) and Ce-bastnasite (100) surfaces using a combination of DFT and MD calculations. Covalent bonds were revealed for four ligand-surface configurations, namely, bidentate, repeated monodentate, staggered monodentate, and neighboring monodentate.…”

“…However, for complexes containing larger adsorbate molecules and/or surfaces with local disorder (such as a deficiency), it is highly plausible to miss a key initial mode, leading to inaccurate prediction of the globally optimized adsorption configuration. Alizadeh Sahraei and Larachi − suggested that the grand canonical Monte Carlo (GCMC) method could be a robust framework for searching all the potential initial configurations in DFT calculations. Their procedure was tested on the adsorption of a molecule, a monolayer and a multilayer of water, and a solvated or nonsolvated amino acid on sphalerite surfaces with and without defects.…”

“…Real minerals almost always contain defects in the form of impurities or vacancies in their crystal lattice or surfaces. Quantum-based molecular modeling techniques are able to describe the electronic properties of deficient mineral surfaces. − ,,,− The role of vacancies on the wettability of sphalerite depends on the type of surface vacancies (Zn or S) as demonstrated by DFT calculations integrated with the GCMC method on the (110) cleavage plane of sphalerite (Figure ). − The S (Zn) vacancy produces a hydrophobic (hydrophilic) region around the deficient site, thereby potentially changing the dominant adsorption pattern of a reagent on the surface .…”

Insight into the Binding Mechanisms of Quartz-Selective Peptides: Toward Greener Flotation Processes

“…Many of today’s synthetically produced reagents are problematic in terms of environmental acceptability, and their replacement for greener flotation practices has become imperative. In this context, there has been a recent surge of research toward exploiting the potential of biomolecules, chiefly amino acids and peptides, as alternatives. − Developing new biobased alternatives will depend on how well one can distinguish peptides according to their selective binding to specific minerals. A failure to understand the peptide–inorganic interactions would fundamentally limit progress in the rational design of the peptide chains that are optimized for each technological application.…”