Effect of contact time, pH, and ionic strength on Cd(II) adsorption from aqueous solution onto bentonite from Gaomiaozi, China

Bentonite has been studied extensively because of its strong adsorption capacity. The Gaomiaozi (GMZ) bentonite is selected as the first choice of Chinese buffer materials for the high-level radioactive waste repository. The adsorption of Cd(II) on the GMZ bentonite as a function of contact time, pH...

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Bibliographic Details
Published in:Environmental earth sciences 2011-09, Vol.64 (2), p.329-336
Main Authors: Chen, Yong-Gui, Ye, Wei-Min, Yang, Xiao-Min, Deng, Fei-Yue, He, Yong
Format: Article
Language:English
Subjects:
Adsorption
Aqueous solutions
Bentonite
Biogeosciences
buffers
Cadmium
Clay
Earth and Environmental Science
Earth Sciences
Earth, ocean, space
Engineering and environment geology. Geothermics
Environmental Science and Engineering
Exact sciences and technology
Geochemistry
Geology
Hazardous wastes
Hydrology/Water Resources
Ion exchange
Kinetics
Original Article
Pollution, environment geology
Radioactive wastes
Terrestrial Pollution
Waste materials
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Summary:Bentonite has been studied extensively because of its strong adsorption capacity. The Gaomiaozi (GMZ) bentonite is selected as the first choice of Chinese buffer materials for the high-level radioactive waste repository. The adsorption of Cd(II) on the GMZ bentonite as a function of contact time, pH, ionic strength, bentonite content, and Cd(II) concentration was studied by using batch technique. The adsorption process achieved equilibrium within 50 min, and the adsorption capacity of Cd(II) by the raw GMZ bentonite was about 3.16 mg/g under the given experimental conditions. The adsorption ability of the GMZ bentonite increases with increasing pH at 2–12 but decreases with increasing ionic strength from 0.01 to 0.1 M KNO 3 . The uptake of Cd(II) on this bentonite increases in response to an increase of the bentonite content. Chemisorption was considered to be a key of process and adsorption mechanism could be concluded to be complexation, ion exchange, and electrostatic interaction. The equilibrium adsorption data were fitted to the second-order kinetic equation. Furthermore, the Langmuir adsorption isotherm model was used for the description of the adsorption process very well.
ISSN:1866-6280
1866-6299
DOI:10.1007/s12665-010-0850-6