The influence of temperature on the adsorption of cadmium(II) and cobalt(II) on goethite

Journal Article · Mon Mar 15 04:00:00 EST 1999 · Journal of Colloid and Interface Science

DOI:https://doi.org/10.1006/jcis.1998.6010· OSTI ID:338564

Angove, M J; Wells, J D; Johnson, B B ^[1]

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1. La Trobe Univ., Bendigo, Victoria (Australia). Div. of Physical Sciences and Engineering

The adsorption of Cd(II) and Co(II) onto goethite was measured at five temperatures between 10 and 70 C. For both cations the amount adsorbed at any given pH increased as the temperature was increased. Cd(II) adsorbed at a slightly lower pH at each temperature than Co(II). Adsorption isotherms at pH 7.00 for Cd(II) could be fitted closely by a simple Langmuir model, but a two-site Langmuir model was needed for Co(II). Potentiometric titrations of goethite suspensions in the presence and absence of added cation could be modeled closely by a constant-capacitance surface complexation model that assumed the adsorption reactions M{sup 2+} + SOH {r_equilibrium} SOM{sup +} + H{sup +} and M{sup 2+} + SOH + H{sub 2}O {r_equilibrium} SOMOH + 2H{sup +}, where M represents Cd or Co. This model also fitted the experimental data from the adsorption edge and adsorption isotherm experiments. Thermodynamic parameters estimated from both Langmuir and surface complexation models showed that the adsorption of both metals was endothermic. Values obtained for the adsorption enthalpies from both modeling schemes were similar for both cations. Estimates of the adsorption entropies were model-dependent: Langmuir parameters yielded positive entropies, while some of the surface complexation parameters generated negative adsorption entropies.

• OSTI ID: 338564
• Journal Information: Journal of Colloid and Interface Science, Journal Name: Journal of Colloid and Interface Science Journal Issue: 2 Vol. 211; ISSN 0021-9797; ISSN JCISA5
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ADSORPTION
ADSORPTION ISOTHERMS
CADMIUM
COBALT
ENVIRONMENTAL TRANSPORT
GOETHITE
MATHEMATICAL MODELS
PH VALUE
SOILS
SORPTIVE PROPERTIES
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES