Modeling the adsorption of divalent metallic cations onto multi-walled carbon nanotubes functionalized with COOH

•Application of physical model with two adsorption energies.•The adsorption is a multi-cationic process.•Determination of adsorption energies for both functional groups.•Study the impact of temperature on all model parameters. In this work, the adsorption of Cd2+, Pb2+, and Hg2+ ions onto multi-wall...

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Published in:Journal of molecular liquids 2022-11, Vol.366, p.120275, Article 120275
Main Authors: Sellaoui, Lotfi, Schnorr, Carlos E., Dhaouadi, Fatma, Taamalli, Sonia, Louis, Florent, El Bakali, Abderrahman, Dotto, Guilherme L., Silva, Luis F.O., Ben Lamine, Abdemottaleb, Rtimi, Sami, Erto, Alessandro
Format: Article
Language:English
Subjects:
Cadmium
Carbon nanotubes
Chemical Sciences
Lead
Mercury
Metal cations
Physics
Statistical physics modeling
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Summary:•Application of physical model with two adsorption energies.•The adsorption is a multi-cationic process.•Determination of adsorption energies for both functional groups.•Study the impact of temperature on all model parameters. In this work, the adsorption of Cd2+, Pb2+, and Hg2+ ions onto multi-walled carbon nanotubes (MWCNTs) functionalized with COOH is investigated as a function of temperature (298–328 K). For all the investigated ions, adsorption shows the classical exothermic behavior, as adsorption capacity decreases by increasing the temperature. Moreover, a saturation value of adsorption capacity is reached for all the metal cations, testifying the possible formation of a monolayer on the adsorbent surface. Two adsorption models derived from statistical physics are tested to address the investigated system's behavior. The monolayer with double functional groups is selected as the best fitting one. The analysis of model parameters shows that the adsorption of the investigated metals is multi-cationic, i.e. each functional group can adsorb several ions simultaneously. Moreover, an increase in temperature determines a decrease in the density of functional groups; for Cd2+ and Pb2+ ions it is associated with an adsorption capacity on the first functional group higher than the corresponding value obtained for the second, while for Hg2+ ions, an opposite result is retrieved. Finally, adsorption energies are determined for both the functional groups, resulting in the typical range of physical adsorption.
ISSN:0167-7322
1873-3166
DOI:10.1016/j.molliq.2022.120275