Interfacial reactions of Cu(ii) adsorption and hydrolysis driven by nano-scale confinement

Abstract

Spatial confinement of silica surfaces leads to increased polymerization of adsorbed copper(ii) species.

Interplay of physically different properties leading to challenges in separating lanthanide cations – an ab initio molecular dynamics and experimental study

“…The experiments were performed on silica surfaces with ∼2 SiOH groups per nm 2 of surface, as discussed in our earlier publication. 28 The lanthanide adsorption data was fit using the Langmuir isotherm model. Based on the fitting, the maximum adsorption coverage for Eu 3+ was estimated at 20.4 µmoles/g, and the Langmuir constant K L was 0.102 L/g.…”

“…We used commercially available fumed silica (Sigma Aldrich) with surface area of 192±3 m 2 g −1 as reported in our earlier work. 28 No background electrolyte or buffer were used. Milli-Q water with the resistivity of 18 MΩ•cm was used for all stock solutions and experiments.…”

First-principles Molecular Dynamics maps out complete mineral surface acidity landscape

“…Another emerging topic of interest is pH-dependent ion dimerization and polymerization on mineral surfaces, which involve more than a single ion and may mark the onset of heterogeneous nucleation and precipitation. Cu(II) in Cu-dimers on silica nanopores are found to be linked by two hydroxide bridges (Knight et al 2020). Similar behavior is seen in Al(III) dimers in water (Schenter et al 2018).…”

Ab initio molecular dynamics free energy study of enhanced copper (II) dimerization on mineral surfaces

“…A dsorption and trapping of metal cations on to material and mineral surfaces at low ion coverages are key geochemical topics that are much studied for mineral growth and dissolution 1,2 , ion exchange 3 , toxic ion remediation 4 , particle attachment 5 , harvesting Li or actinides from sea water 6 , and other applications related to critical elements [7][8][9][10][11] . The surface density and speciation of adsorbed metal cations depend on the material surface chemistry, binding sites, electric double layers, pH, and salt concentrations.…”

“…At intermediate surface coverage, divalent and trivalent metal cation clusters ("dimers") and polymeric species have been demonstrated to adsorb on mineral surfaces, clay edges, and in confined aqueous media using X-ray absorption fine structure (XAFS) spectroscopy measurements 4,[17][18][19][20][21][22][23][24][25] . The surface concentration of dimers strongly affects cation uptake, especially as pH varies 23 .…”