ADSORPTION OF ZINC AND COPPER IONS ON NATURAL AND ETHYLENEDIAMINE MODIFIED MONTMORILLONITE

The adsorption of the zinc and copper ions on montmorillonite (MMT) was investigated. In all the experiments performed at pH 6.4 to 4.8, the Langmuir-Freundlich isotherm was the best fit for the adsorption data and confirmed a monolayer formation by the metals. The maximum amounts of the adsorbed me...

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Bibliographic Details
Published in:Ceramics (Praha) 2010-01, Vol.54 (1), p.78-84
Main Authors: Kozak, O, Praus, P, Machovic, V, Klika, Z
Format: Article
Language:English
Subjects:
Adsorption
Copper
Ethylenediamine
Interlayers
Montmorillonite
Spectrometry
Spectroscopy
Zinc
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Summary:The adsorption of the zinc and copper ions on montmorillonite (MMT) was investigated. In all the experiments performed at pH 6.4 to 4.8, the Langmuir-Freundlich isotherm was the best fit for the adsorption data and confirmed a monolayer formation by the metals. The maximum amounts of the adsorbed metals did not exceed the cation exchange capacity (CEC) of MMT. UV-VIS diffuse reflectance spectrometry revealed no complexes between Zn2+ or Cu2+ and MMT and thus the metal uptake took part only by ion exchange. XRD indicated an intercalation of the metal ions into the montmorillonite interlayer. TGA and IR spectrometry showed that the intercalated metals created aqua complexes [Zn(H2O)6]2+ and [Cu(H2O)6]2+. To increase the adsorbed amounts of Zn2+ and Cu2+, MMT was pre-intercalated with ethylenediamine (EDA-MMT). EDA caused an increase in the adsorbed amount of copper ions to about 28% due to the formation of [Cu(EDA)2]2+ in the interlayer as confirmed by IR spectrometry. The adsorbed amount of zinc ions on EDA-MMT was 3-4 times higher than by CEC but no complex with EDA was observed. This effect was explained by the expansion of a space between the montmorillonite layers, which facilitated the intercalation of the zinc ions and nitrate compensating for the excessive positive charge.
ISSN:0862-5468