Adsorption of Ions on the Surface of Tin Dioxide and Its Electrokinetic Characteristics in 1 : 1 Electrolyte Solutions

Bogdanova, N. F.; Klebanov, A. V.; Ермакова, Л. Э.; Sidorova, M. P.; Aleksandrov, Dmitry

doi:10.1023/b:coll.0000037445.08721.85

Cited by 13 publications

(4 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The IEP of zircon is higher than that of cassiterite. Bogdanova et al reported the IEP of cassiterite was located in the region of 3.8−5.5, depending on the sample origin, type of electrolyte, and the determination procedure [21]. In addition, the measured data of cassiterite and zircon were in excellent agreement with the results reported by Wang et al [22] and Moreno et al [23], respectively.…”

Section: Adsorption Testssupporting

confidence: 73%

Study on the Effect of Fe3+ on Zircon Flotation Separation from Cassiterite Using Sodium Oleate as Collector

Peng

Luo

et al. 2017

Minerals

View full text Add to dashboard Cite

The effect of ferric ions (Fe 3+ ) on the flotation of zircon and cassiterite using sodium oleate (NaOL) was investigated by single mineral flotation tests, adsorption density tests, zeta potential measurements, solution chemistry analyses, and FTIR analyses. It is difficult for zircon to be separated from cassiterite by using NaOL alone. Nevertheless, the flotation of zircon was activated while that of cassiterite was depressed in the presence of Fe 3+ . Adsorption density tests indicated that the addition of Fe 3+ enhanced the adsorption of NaOL on zircon surfaces, whereas it receded on cassiterite surfaces. Zeta potential measurements and solution chemistry analyses found that H(OL) − 2 was the predominant species to determine the flotation behaviors of zircon and cassiterite. Furthermore, the addition of Fe 3+ at pH < 8 reduced the negative charges on the zircon and cassiterite surfaces. It was confirmed that the positive charges of zircon were caused by the positively charged species of Fe 3+ , including Fe 3+ , Fe(OH) 2+ , and Fe(OH) + 2 . Meanwhile, these results revealed that the hydroxy complex and the precipitate of Fe(OH) 3 (s) adsorbed onto the cassiterite surfaces caused the flotation of cassiterite to be inhibited. It can be concluded from FTIR analyses that the peaks of zircon at 894.14 cm −1 and 611.65 cm −1 were strengthened and the adsorption on zircon surfaces was found to be chemisorption due to the addition of Fe 3+ , whereas both chemical and physical adsorptions of NaOL on cassiterite surfaces were weakened, resulting in the different flotation behaviors of zircon and cassiterite in the presence of Fe 3+ .Minerals 2017, 7, 108 2 of 18 first stage, and the product of zircon from the first stage then needs further processing. However, gravity separation methods will perform well only when the particle size meets the requirements [6]. Both too fine and coarse particle sizes will negatively affect the results. Hence, the fine fraction of zircon concentrate from gravity separation still contains large amounts of impurities which cannot be removed effectively. To improve the quality of products, zircon is further separated from other heavy minerals, such as magnetite, ilmenite, and cassiterite, by a series of magnetic and electrostatic separation processes. Usually, the removal of magnetite and ilmenite from zircon is easier to achieve via magnetic separation because these two minerals are magnetic. The electrostatic separation method [7] based on the different electric properties between the gangue and the valuable minerals requires clean mineral surfaces. The mineral surfaces of zircon are usually coated with some electric metal minerals which contain titanium, iron, and other materials such as clay. These contaminants make it very difficult to achieve an effective separation using electrostatic separation. According to the information mentioned above, the light minerals and magnetic minerals can be removed, and cassiterite as the main contaminant in zircon concentrate cannot be removed effecti...

show abstract

Section: Adsorption Testssupporting

confidence: 73%

Study on the Effect of Fe3+ on Zircon Flotation Separation from Cassiterite Using Sodium Oleate as Collector

Peng

Luo

et al. 2017

Minerals

View full text Add to dashboard Cite

show abstract

“…A pH znpc of ∼4.3 at 25 °C agrees well with previously reported values. Kosmulski gives a median value of 4.4 for SnO 2 at 25 °C, whereas Bogdanova et al found a pH znpc of 4.1 ± 0.1 at 20 °C in their study of nanosized SnO 2 . Bogdanova et al found no significant differences in the charging of SnO 2 in NaCl and KCl media, in accord with our findings in NaCl and RbCl media.…”

Section: Resultsmentioning

confidence: 88%

Charging Properties of Cassiterite (α-SnO₂) Surfaces in NaCl and RbCl Ionic Media

et al. 2009

View full text Add to dashboard Cite

The acid-base properties of cassiterite (alpha-SnO2) surfaces at 10-50 degrees C were studied using potentiometric titrations of powder suspensions in aqueous NaCl and RbCl media. The proton sorption isotherms exhibited common intersection points in the pH range of 4.0-4.5 under all conditions, and the magnitude of charging was similar but not identical in NaCl and RbCl. The hydrogen bonding configuration at the oxide-water interface, obtained from classical molecular dynamics (MD) simulations, was analyzed in detail, and the results were explicitly incorporated in calculations of protonation constants for the reactive surface sites using the revised MUSIC model. The calculations indicated that the terminal SnOH2 group is more acidic than the bridging Sn2OH group, with protonation constants (log KH) of 3.60 and 5.13 at 25 degrees C, respectively. This is contrary to the situation on the isostructural alpha-TiO2 (rutile), apparently because of the difference in electronegativity between Ti and Sn. MD simulations and speciation calculations indicated considerable differences in the speciation of Na+ and Rb+, despite the similarities in overall charging. Adsorbed sodium ions are almost exclusively found in bidentate surface complexes, whereas adsorbed rubidium ions form comparable numbers of bidentate and tetradentate complexes. Also, the distribution of adsorbed Na+ between the different complexes shows a considerable dependence on the surface charge density (pH), whereas the distribution of adsorbed Rb+ is almost independent of pH. A surface complexation model (SCM) capable of accurately describing both the measured surface charge and the MD-predicted speciation of adsorbed Na+/Rb+ was formulated. According to the SCM, the deprotonated terminal group (SnOH(-0.40)) and the protonated bridging group (Sn2OH+0.36) dominate the surface speciation over the entire pH range of this study (2.7-10). The complexation of medium cations increases significantly with increasing negative surface charge, and at pH 10, roughly 40% of the terminal sites are predicted to form cation complexes, whereas anion complexation is minor throughout the studied pH range.

show abstract

“…In terms of experimental values, Bogdanova et al found a PZC of 4.1 at 20 °C from potentiometric titrations with nanosized SnO 2 , and Rosenqvist et al obtained a similar PZC value of ∼ 4.3 at 25 °C for tin oxide power using the same titration method. In an earlier work, Ahmed and Maksimov determined the PZC for crystalline cassiterite to be in the range 4.8–5.5.…”

Section: Results and Discussionmentioning

confidence: 97%

Computing Surface Acidity Constants of Proton Hopping Groups from Density Functional Theory-Based Molecular Dynamics: Application to the SnO₂(110)/H₂O Interface

Jia

Zhang

Cox

et al. 2020

J. Chem. Theory Comput.

View full text Add to dashboard Cite

Proton transfer at metal oxide/water interfaces plays an important role in electrochemistry, geochemistry and environmental science. The key thermodynamic quantity to characterize this process is the surface acidity constant. An ab initio method that combines density functional theory based molecular dynamics (DFTMD) and free energy perturbation theory has been established for computing surface acidity constants. However, it involves a reversible proton insertion procedure in which frequent proton hopping, e.g. for strong bases and some oxide surfaces (e.g. SnO2), can cause instability issues in electronic structure calculation. In the original implementation, harmonic restraining potentials are imposed on all O-H bonds (denoted by the VrH scheme) to prevent proton hopping, and thus may not be applicable for systems involving spontaneous proton hopping. In this work, we introduce an improved restraining scheme with a repulsive potential Vrep to compute the surface acidities of systems in which proton hopping is spontaneous and fast. In this Vrep scheme, a Buckingham-type repulsive potential Vrep is applied between the deprotonation site and all other protons in DFTMD simulations. We first verify the Vrep scheme by calculating the pKa's of H2O and aqueous HSsolution (i.e. strong conjugate bases), and then apply it to the SnO2(110)/H2O interface. It is found that the Vrep scheme leads to a prediction of the point of zero charge (PZC) of 4.6, which agrees well with experiment. The intrinsic individual pKa of terminal five-coordinated Sn site (Sn5cOH2) and bridge oxygen site (Sn2ObrH + ) are 4.4 and 4.7, respectively, both being almost the same as the PZC. The similarity of the two pKa values indicate that dissociation of terminal water has almost zero free energy at this proton hopping interface (i.e. partial water dissociation), as expected from the acid-base equilibrium on SnO2.

show abstract

Adsorption of Ions on the Surface of Tin Dioxide and Its Electrokinetic Characteristics in 1 : 1 Electrolyte Solutions

Cited by 13 publications

References 8 publications

Study on the Effect of Fe3+ on Zircon Flotation Separation from Cassiterite Using Sodium Oleate as Collector

Study on the Effect of Fe3+ on Zircon Flotation Separation from Cassiterite Using Sodium Oleate as Collector

Charging Properties of Cassiterite (α-SnO₂) Surfaces in NaCl and RbCl Ionic Media

Computing Surface Acidity Constants of Proton Hopping Groups from Density Functional Theory-Based Molecular Dynamics: Application to the SnO₂(110)/H₂O Interface

Contact Info

Product

Resources

About

Adsorption of Ions on the Surface of Tin Dioxide and Its Electrokinetic Characteristics in 1 : 1 Electrolyte Solutions

Cited by 13 publications

References 8 publications

Study on the Effect of Fe3+ on Zircon Flotation Separation from Cassiterite Using Sodium Oleate as Collector

Study on the Effect of Fe3+ on Zircon Flotation Separation from Cassiterite Using Sodium Oleate as Collector

Charging Properties of Cassiterite (α-SnO2) Surfaces in NaCl and RbCl Ionic Media

Computing Surface Acidity Constants of Proton Hopping Groups from Density Functional Theory-Based Molecular Dynamics: Application to the SnO2(110)/H2O Interface

Contact Info

Product

Resources

About

Charging Properties of Cassiterite (α-SnO₂) Surfaces in NaCl and RbCl Ionic Media

Computing Surface Acidity Constants of Proton Hopping Groups from Density Functional Theory-Based Molecular Dynamics: Application to the SnO₂(110)/H₂O Interface