Behavior and mechanism of Cd(II) adsorption on loess-modifi ed clay liner

Cadmium is a toxic heavy metal which is common in landfi ll leachate and it has caused seriouspublic health problems. It is necessary to fi nd a cost effective method to deal with landfi ll leachatecontaining Cd(II). The loess-modifi ed clay is proved to be effective to remove Cd(II) removalfrom lan...

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Bibliographic Details
Published in:Desalination and water treatment 2012-02, Vol.39 (1-3), p.10-20
Main Authors: Yanga, Qinglei, Zhang, Jinli, Yang, Qing, Yu, Yongxian, Yang, Gang
Format: Article
Language:English
Subjects:
Adsorption
Cadmium
Isotherm
Kinetics
Landfill liners
Loess-modifi ed clay
Thermodynamics
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Summary:Cadmium is a toxic heavy metal which is common in landfi ll leachate and it has caused seriouspublic health problems. It is necessary to fi nd a cost effective method to deal with landfi ll leachatecontaining Cd(II). The loess-modifi ed clay is proved to be effective to remove Cd(II) removalfrom landfi ll leachate. The adsorption capacity of loess-modifi ed clay towards Cd(II) has beendetermined to be about 7.08 mg/g. Factors affecting the adsorption of Cd(II) include loess proportion,slurry concentration, initial solution pH, temperature and event duration. The adsorptionisotherms and kinetic data are well fi t with the Langmuir model and pseudo-second orderkinetics model, respectively. The thermodynamic behavior reveals that the adsorption processis spontaneous and endothermic and the system disorder increases with time. The adsorptionof Cd(II) on loess-modifi ed clay involves chemical reaction and surface complexation with clayminerals. Chemical precipitation is considered as the dominant mechanism at pH>9. Furtherstudies using X-ray diffraction, Fourier transform infrared spectra have confi rmed the adsorptionmechanism. The material used in this paper is economic and environmental protection,which is proved to be appropriate for landfi ll liner material.
ISSN:1944-3986
DOI:10.5004/dwt.2012.2160