Clays and Clay Minerals, Vol. 54, No. 4, 449-455, 2006.
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Authors
Harris, Rodney G.
Johnson, Bruce B.
Wells, John D.
Issue Date
2006
Type
Article
Language
en_US
Keywords
Periodicals , Geology , 9-aminoacridine , 6-diaminoacridine , Azure A , Clay , Displacement , Dye , Isotherm , Kaolin , Safranin O
Alternative Title
Competitive Adsorption of Cd and Dyes to Kaolinite
Abstract
The competitive adsorption to kaolinite between Cd(II) and four polyaromatic dyes (9- aminoacridine, 3,6-diaminoacridine, azure A and safranin O) was studied in 5 mM KNO3 at 25ëC. Under these conditions, Cd adsorbs to the silica face of kaolinite between about pH 4 and 6.5, but at higher pH, adsorbed Cd is progressively relocated to the crystal edges. In the presence of dye, less Cd adsorbed to kaolinite below pH 7. If sufficient dye was added to saturate the kaolinite surface, Cd adsorption was totally suppressed up to ~pH 6. At higher pH, Cd followed the characteristic pattern for edge adsorption. In separate experiments 9-aminoacridine and azure A displaced pre-adsorbed Cd from kaolinite. The displacement curves were initially linear, with one Cd ion being displaced for every 13 dye molecules adsorbed at pH 5.5, and one Cd ion for every 35 dye molecules at pH 7.5. The interpretation of these results is that the dyes bind to kaolinite much more strongly than Cd(II) does, but only to the silica face.
Description
gsccm-54-4-05-ha2.pdf 579KB PDF/A Document.
Citation
Clays and Clay Minerals, Vol. 54, No. 4, 449-455, 2006.
Publisher
The Clay Minerals Society
License
Copyright © 2006-2018.