A comparative study of the adsorption of transition metals on kaolinite

Journal Article · Wed Sep 15 04:00:00 EDT 1999 · Journal of Colloid and Interface Science

DOI:https://doi.org/10.1006/jcis.1999.6377· OSTI ID:20000023

Ikhsan, J; Johnson, B B; Wells, J D

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.

• Research Organization: La Trobe Univ., Bendigo, Victoria (AU)
• OSTI ID: 20000023
• Journal Information: Journal of Colloid and Interface Science, Journal Name: Journal of Colloid and Interface Science Journal Issue: 2 Vol. 217; ISSN 0021-9797; ISSN JCISA5
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
54 ENVIRONMENTAL SCIENCES
ADSORPTION
COPPER
ENVIRONMENTAL TRANSPORT
KAOLINITE
LEAD
MANGANESE
ORE PROCESSING
SORPTIVE PROPERTIES
WASTE PROCESSING
ZINC