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|Title: ||Zn(II) removal using natural bentonite:|
|Authors: ||A. ALDAYEL, O.|
M. ALANDIS, N.
K. MEKHEMER, W.
|Keywords: ||Heavy metals; adsorption; isotherms; natural bentonite; kinetics; thermodynamics ; heat treatment; desorption.|
|Issue Date: ||2008 |
|Publisher: ||Material Science Research India Vol. 55(1), 25-36 (2008)|
|Citation: ||Physical chemistry,|
|Abstract: ||This paper describes the adsorption of Zn(II) from aqueous solutions by commercial natural
bentonite (NB). The contact time, pH of the solution, metal ion concentration, Temperature, adsorbent
doses, bentonite treatment (calcinations of NB at 700°C and washing by deionized water to remove
the excess salt from bentonite surface) on the adsorption process were examined. The washed and
calcined bentonite samples were labeled by WB and CB respectively. The adsorption process follows
pseudo-second-order reaction kinetics. The Langmuir and Freundlich models were used to describe
the adsorption equilibrium of zinc on NB and the adsorption followed the Langmuir isotherm.
The Langmuir and Freundlich constants for adsorption of zinc on NB were determined. This work
discusses the thermodynamic parameters of the adsorption (the Gibbs free energy, entropy, and
enthalpy). Our results demonstrate that the adsorption process was spontaneous and endothermic
under natural conditions. The results show that adsorption behavior of NB was strongly depending on
the pH. The optimum pH for adsorption was found to be 6.0. Also the adsorption capacity of NB for Zn
(II) increases with increased bentonite dose. The adsorbed amount of Zn (II) on WB was increased by
100% compared NB and CB. The results generally showed that bentonite could be considered as a
potential adsorbent for Zn(II) removal from aqueous solutions especially WB.|
|Appears in Collections:||College of Science|
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