Comment on the Article "On the Nature of the Energetic Surface Heterogeneity in Ion Adsorption at a Water/Oxide Interface:Theoretical Studies of Some Special Features of Ion Adsorption at Low Ion Concentrations"

Langmuir ◽  
1994 ◽  
Vol 10 (10) ◽  
pp. 3916-3917 ◽  
Author(s):  
Johannes Luetzenkirchen ◽  
Philippe Behra
Keyword(s):  
Surface Heterogeneity ◽  
Ion Adsorption ◽  
Ion Concentrations

scholarly journals On the Nature of the Energetic Surface Heterogeneity in Ion Adsorption at an Electrolyte/Oxide Interface. Theoretical Studies of the Correlations between Binding-to-Surface Energies of Various Surface Complexes

1996 ◽  
Vol 14 (1) ◽  
pp. 25-38 ◽  
Author(s):  
Wladyslaw Rudziński ◽  
Robert Charmas ◽  
Wojciech Piasecki
Keyword(s):  
Surface Heterogeneity ◽  
Ion Adsorption ◽  
Surface Oxygen ◽  
Oxide Interface ◽  
Surface Complexes ◽  
Surface Energies ◽  
Outermost Surface ◽  
Energetic Heterogeneity ◽  
Total Lack ◽  
Oxide Electrolyte

When a metal oxide is brought into contact with an electrolyte, the outermost surface oxygens adsorb one or two protons, a cation or an aggregate composed of two protons and an anion. In this way, various surface complexes are formed. The actual surfaces are, as a rule, geometrically distorted. This causes a variation of the binding-to-surface energy from one surface oxygen to another for each of these complexes. This energetic heterogeneity of the actual oxide surfaces strongly affects the adsorption of ions within the electrical double layer formed at the oxide/electrolyte interface. The way in which the surface heterogeneity affects the adsorption of ions depends on the correlations between the binding-to-surface energies of the various surface complexes. To date, two extreme models have been considered by us; one assuming the existence of very high correlations, and the other one assuming a total lack of correlation between binding-to-surface energies in going from one surface oxygen to another. This paper presents a theoretical study of ion adsorption based on the assumption of a partial correlation between the binding-to-surface energies.

scholarly journals Removal of Cu2+ Ions from Aqueous Solutions by Carbon Nanotubes

2003 ◽  
Vol 21 (5) ◽  
pp. 475-485 ◽  
Author(s):  
Yan-Hui Li ◽  
Zhaokun Luan ◽  
Xu Xiao ◽  
Xiangwen Zhou ◽  
Cailu Xu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Adsorption Capacity ◽  
Kinetic Curve ◽  
Crystalline Form ◽  
Ion Adsorption ◽  
Ion Concentrations ◽  
Ion Removal ◽  
A Value

Carbon nanotubes (CNTs), a new crystalline form in the carbon family, have been shown to be an effective adsorbent for Cu2+ ion removal from aqueous solution. After oxidation with nitric acid, the adsorption capacity of the oxidized CNTs towards Cu2+ ions at a pH of 5.2 reached 27.6 mg/g, compared to a value of only 14.4 mg/g for the as-grown CNTs under the same circumstances. Increasing the pH to 5.4 led to 95% removal of Cu2+ ions with the oxidized CNTs, whereas with the as-grown CNTs it was necessary to increase the pH to 8.6 to achieve the same extent of removal. The Cu2+ ion adsorption capacity increased with increasing CNT dosage for the different initial Cu2+ ion concentrations. The kinetic curve for adsorption of the Cu2+ ions suggested that not only the outer surfaces but also inner cavities and inter-layers in the structures of the CNTs were responsible for the removal of the ion from aqueous solutions.

Effect of Ion Adsorption with Various Hydrolysis Characteristics on the Dewaterability of Fe2O3 Sludge

1993 ◽  
Vol 28 (7) ◽  
pp. 23-30 ◽  
Author(s):  
Yung-Hsu Hsieh
Keyword(s):  
Water Molecule ◽  
Surface Charge ◽  
Ion Concentration ◽  
Ion Adsorption ◽  
Ion Concentrations ◽  
Molecule Structure ◽  
Zeta Potentials

In the presence of ions with various hydrolysis characteristics, the water-molecule structure and surface charge on iron sludge colloids can be changed and the dewaterability of iron sludge will also be affected. Such effects were studied in the laboratory through determinations of zeta potentials and specific the resistance of Fe2O3 sludge particles. It was found from experiments in the presence of ions with various hydrolysis characteristics in the iron sludge solutions, that the dewaterabilities of iron sludges showed the orders Cl− > Br− > I− and IO3− > BrO3− > C1O3− for anions, and Li+ > Na+ > K+ > Rb+ > Cs+ and Mg2+ > Ca2+ > Sr2+ ∼ Ba2+ for cations. In the presence of ions of different concentrations, the change in zeta potentials and the improvement of dewaterabilities of iron sludge particles followed the order lO−2M > 10−3M > lO−M for both IO3− and Li+; although the change in zeta potentials increased with the ion concentration for I− and Cs+, the dewaterabilities of iron sludges were depressed with increasing ion concentrations.

Effects of surface heterogeneity on ion adsorption by metal oxides and by soils

Langmuir ◽  
1993 ◽  
Vol 9 (10) ◽  
pp. 2606-2611 ◽  
Author(s):  
N. J. Barrow ◽  
G. W. Bruemmer ◽  
R. Strauss
Keyword(s):  
Metal Oxides ◽  
Surface Heterogeneity ◽  
Ion Adsorption
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