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Dynamic adsorption of Cd (super 2+) onto acid-modified attapulgite from aqueous solution

Guo Na, Wang Jinsheng, Li Jian, Teng Yanguo and Zhai Yuanzheng
Dynamic adsorption of Cd (super 2+) onto acid-modified attapulgite from aqueous solution
Clays and Clay Minerals (October 2014) 62 (5): 415-424

Abstract

In the present study, acid-modified attapulgite was used, as an adsorbent, to remove as much Cd (super 2+) as possible from aqueous solution. Static adsorption experiments using powdered acid-modified attapulgite, and dynamic adsorption using granular acid-modifed attapulgite, were conducted to explore the practical application of modified attapulgite in the adsorption of Cd (super 2+) . The modified attapulgite had a larger specific surface area and thinner fibrous crystals than the unmodified version. No obvious differences were noted, in terms of the crystal structure, between the natural attapulgite and the modified version. The effects of initial concentration, pH, contact time, and ionic strength on the adsorption of Cd (super 2+) were investigated, and the results showed that the adsorption capacity of the modified attapulgite was increased with increasing pH and the initial Cd (super 2+) concentration. The adsorption properties were analyzed by means of dynamic adsorption tests with respect to various Cd (super 2+) concentrations and flow rates. The maximum adsorption capacity of 8.83 mg/g occurred at a flow rate of 1 mL/min and at an initial concentration of 75 mg/L. Because there was better accord between the data and a pseudo-second order model than a pseudo-first-order model, external mass transfer is suggested to be the rate-controlling process. The experimental data were also fitted for the intraparticle diffusion model, implying that the intraparticle diffusion of Cd (super 2+) onto the modified attapulgite was also important for controlling the adsorption process. The Bohart-Adams model was more suitable than the Thomas model for describing the dynamic behavior with respect to the flow rate and the initial Cd (super 2+) concentration. This research provided the theoretical basis for the dynamic adsorption of Cd (super 2+) on the modified attapulgite. Compared to the powdered modified attapulgite, the dynamic adsorption by granular modified attapulgite appeared more favorable in terms of practical application.


ISSN: 0009-8604
EISSN: 1552-8367
Coden: CLCMAB
Serial Title: Clays and Clay Minerals
Serial Volume: 62
Serial Issue: 5
Title: Dynamic adsorption of Cd (super 2+) onto acid-modified attapulgite from aqueous solution
Affiliation: Beijing Normal University, College of Water Sciences, Beijing, China
Pages: 415-424
Published: 201410
Text Language: English
Publisher: Clay Minerals Society, Chantilly, VA, United States
References: 49
Accession Number: 2015-091704
Categories: Geochemistry of rocks, soils, and sedimentsEnvironmental geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables
N30°45'00" - N35°00'00", E116°30'00" - E122°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Clay Minerals Society. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201539
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