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Adsorption of copper and zinc onto natural clay in single and binary systems
Sdiri, A. T.; Higashi, T. & Jamoussi, F.
Abstract
Calcareous and smectitic clay samples from the
Coniacian–Lower Campanian system, Tunisia, were used
as adsorbents for the removal of copper and zinc from
aqueous solutions in single and binary systems. Calcareous
clay sample was treated with acetic acid to obtain carbonate-
free sample that was also used for metals removal.
The adsorption of metal ions onto natural clay was tested in
a batch method by mixing 1 g/L of each sample with a
metal ion solution of zinc (300 μmol/L) and/or copper
600 μmol/L under the operating pH of 6, and agitation
speed of 200 rpm within the equilibrium time of 60 min at
25 °C for single and binary systems. Our results showed
that natural clay samples were mainly composed of silica,
alumina, iron, and magnesium oxides. Adsorption data
showed that the studied clay samples removed substantial
amounts of heavy metals in single and mixed systems.
Initial solution pH and carbonates contents enhanced the
removal capacities of the studied clay samples, confirming
their strong influencing effects. Thermodynamic parameters
indicated an endothermic adsorption for metals
removal by calcareous clay, but exothermic process for
the smectitic sample. These results suggest that the Late
Cretaceous clays, Tunisia, can be effectively used as natural
adsorbents for the removal of toxic heavy metals in
aqueous systems.
Keywords
Clays; Competitive Langmuir model; Heavy metals; Thermodynamic; Sorption
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