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

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 Capacitive deionization: a promising technology for water defluoridation: a review

2021 ◽  
Author(s):  
Tusekile Alfredy ◽  
Joyce Elisadiki ◽  
Yusufu Abeid Chande Jande
Keyword(s):  
Metal Oxides ◽  
High Selectivity ◽  
Electrode Materials ◽  
Review Paper ◽  
High Surface ◽  
High Surface Area ◽  
Ionic Species ◽  
Ion Adsorption ◽  
Capacitive Deionization ◽  
Commercial Scale

Abstract Capacitive deionization (CDI) is among the promising technologies employed for water purification. CDI has been studied for the removal of various ionic species from water including fluoride ion (F−) with promising results. However, there is no comprehensive literature that summarizes the use of CDI for water defluoridation applications. Therefore, this review paper critically analyzes different electrode materials that have been studied for water defluoridation, their electrosorption capacities and F− removal efficiencies. It further discussed the parameters that influence CDI efficiency during defluoridation and point out the issues of F− selectivity when coexisting with other ions in the solution. We can conclude that different electrode materials have shown different abilities in electrosorption of F−. The carbon-based materials possess high surface area and good electrical conductivity which is paramount for ion adsorption but lack selectivity for F− removal. Metal oxides and hydroxides have been reported with improved electrosorption capacity and high selectivity to F− due to the ion exchange between the F− and the hydroxyls surface of the metal oxides/hydroxides. Apart from the good performance of these materials for defluoridation, the discovery of actual practicability use of the electrode materials for defluoridation for commercial scale is still a need.

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