Adsorption mechanisms of metal cations from water on an oxidized carbon surface

Acidity constant distributions at 288 K ( ▪) and 308 K ( ▪) of the surface oxygen groups of the oxidized activated carbon. Adsorption of Cr(III), Mn(II), Cu(II) and Zn(II) on an oxidized activated carbon cloth was studied. Its surface chemistry was characterized by potentiometric titration. This tec...

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Bibliographic Details
Published in:Journal of colloid and interface science 2010-05, Vol.345 (2), p.461-466
Main Authors: Moreno-Castilla, C., Álvarez-Merino, M.A., Pastrana-Martínez, L.M., López-Ramón, M.V.
Format: Article
Language:English
Subjects:
Activated carbon
Adsorbents
Adsorption
Carbon
Cations
Chemistry
Cloth
Colloidal state and disperse state
Divalent cations
Exact sciences and technology
General and physical chemistry
Inner-sphere mechanism
Metal ion adsorption
Outer-sphere mechanism
Oxidized carbon surface
Surface chemistry
Surface physical chemistry
Titration
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Summary:Acidity constant distributions at 288 K ( ▪) and 308 K ( ▪) of the surface oxygen groups of the oxidized activated carbon. Adsorption of Cr(III), Mn(II), Cu(II) and Zn(II) on an oxidized activated carbon cloth was studied. Its surface chemistry was characterized by potentiometric titration. This technique revealed the amount of surface oxygen functionalities and their acidity constant distribution. The acidity constant range involved in the metal cation adsorption was obtained from this distribution. Metal cation adsorption increased with higher adsorption temperature due to the increase in the negative surface charge of the oxidized activated carbon. Adsorption was by proton exchange and the number, amount and strength of the surface acid groups involved could be obtained. The proton exchange was by an inner-sphere or outer-sphere surface metal complex formation mechanism. In the case of divalent cation adsorption, the increase in temperature changed the adsorption mechanism from outer-sphere to inner-sphere. However, the adsorption mechanism of Cr(III) was outer-sphere and independent of temperature. Adsorption capacity augmented with the increase in the charge-to-size ratio of the hexa-aquo cations. In addition, the adsorption capacity of divalent cations increased with the rise in stability of the surface metal complex formed.
ISSN:0021-9797
1095-7103
DOI:10.1016/j.jcis.2010.01.062