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Adsorption Behaviour of Modified Organobentonite with Dithizone for Hg(II) in Water and Its Application for Concentration and Separation of Hg(II) in Surface Water
Corresponding Author(s) : Dong Zhang
Asian Journal of Chemistry,
Vol. 25 No. 17 (2013): Vol 25 Issue 17
Abstract
In this paper, the adsorption behaviour of modified organobentonite with dithizone (D-O-bentonite) for mercury(II) in water was investigated. Optimal experimental conditions for the adsorption of the mercury, including pH, contact time, eluent concentration and volume and co-existing ions have been studied. Moreover, the thermodynamics and kinetics of the adsorption were completely investigated. The result showed that the Hg(II) could be adsorbed on the D-O-bentonite. The adsorbed quantity was affected by the pH value of medium and contact time. The isothermal data was described by the Langmuir equation. The dynamic data followed the pseudo-second-order kinetic model well. The enthalpy change (DH) of the adsorption process was 14.20 kJ/mol. Gibbs free energy changes (DG) were negative and entropy changes (DS) were positive. The activation energy (Ea) was 14.06 kJ/mol for the adsorption. The mercury adsorbed on the D-O-bentonite could be completely eluated by using 3 mol/L HCl. The adsorption agent has been applied to the pre-concentration/ separation of Hg(II) in surface water samples with satisfied results.
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