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Title: A comparative study of the adsorption of transition metals on kaolinite

Abstract

Adsorption of Pb(II), Cu(II), Zn(II), Co(II), and Mn(II) to kaolinite was measured at 25 C in the presence of 5 mM KNO{sub 3}. Adsorption edges (pH 3--10; total metal concentration 100 {micro}M) for Pb(II) and Cu(II) were sigmoid, but those for Zn(II) and Co(II) and especially Mn(II), were characterized by distinct steps after about 40% adsorption. Adsorption isotherms (concentrations up to 60 {micro}M; fixed pH) at pH 5.50 followed the simple Langmuir equation, but those at pH 7.50 (Zn(II), Co(II), and Mn(II)) required a two-site model. More protons were released during adsorption at the higher pH. All adsorption data, and the results of potentiometric titrations of kaolinite suspensions (alone and in the presence of metals at 100 {micro}M), can be fitted closely by a constant-capacitance surface complexation model that incorporates two bidentate surface complexes. One involves electrostatic attraction between transition metal ions and the permanent, negatively charged sites on the silanol faces of kaolinite. The other is an inner-sphere complex at the variable-charge surface hydroxyl groups situated at the crystal edges and on the aluminol faces.

Authors:
; ;
Publication Date:
Research Org.:
La Trobe Univ., Bendigo, Victoria (AU)
OSTI Identifier:
20000023
Resource Type:
Journal Article
Journal Name:
Journal of Colloid and Interface Science
Additional Journal Information:
Journal Volume: 217; Journal Issue: 2; Other Information: PBD: 15 Sep 1999; Journal ID: ISSN 0021-9797
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 54 ENVIRONMENTAL SCIENCES; KAOLINITE; SORPTIVE PROPERTIES; ADSORPTION; LEAD; COPPER; ZINC; MANGANESE; ENVIRONMENTAL TRANSPORT; ORE PROCESSING; WASTE PROCESSING

Citation Formats

Ikhsan, J., Johnson, B.B., and Wells, J.D. A comparative study of the adsorption of transition metals on kaolinite. United States: N. p., 1999. Web. doi:10.1006/jcis.1999.6377.
Ikhsan, J., Johnson, B.B., & Wells, J.D. A comparative study of the adsorption of transition metals on kaolinite. United States. doi:10.1006/jcis.1999.6377.
Ikhsan, J., Johnson, B.B., and Wells, J.D. Wed . "A comparative study of the adsorption of transition metals on kaolinite". United States. doi:10.1006/jcis.1999.6377.
@article{osti_20000023,
title = {A comparative study of the adsorption of transition metals on kaolinite},
author = {Ikhsan, J. and Johnson, B.B. and Wells, J.D.},
abstractNote = {Adsorption of Pb(II), Cu(II), Zn(II), Co(II), and Mn(II) to kaolinite was measured at 25 C in the presence of 5 mM KNO{sub 3}. Adsorption edges (pH 3--10; total metal concentration 100 {micro}M) for Pb(II) and Cu(II) were sigmoid, but those for Zn(II) and Co(II) and especially Mn(II), were characterized by distinct steps after about 40% adsorption. Adsorption isotherms (concentrations up to 60 {micro}M; fixed pH) at pH 5.50 followed the simple Langmuir equation, but those at pH 7.50 (Zn(II), Co(II), and Mn(II)) required a two-site model. More protons were released during adsorption at the higher pH. All adsorption data, and the results of potentiometric titrations of kaolinite suspensions (alone and in the presence of metals at 100 {micro}M), can be fitted closely by a constant-capacitance surface complexation model that incorporates two bidentate surface complexes. One involves electrostatic attraction between transition metal ions and the permanent, negatively charged sites on the silanol faces of kaolinite. The other is an inner-sphere complex at the variable-charge surface hydroxyl groups situated at the crystal edges and on the aluminol faces.},
doi = {10.1006/jcis.1999.6377},
journal = {Journal of Colloid and Interface Science},
issn = {0021-9797},
number = 2,
volume = 217,
place = {United States},
year = {1999},
month = {9}
}