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Investigations into the kinetics and thermodynamics of Sb(III) adsorption on goethite (α-FeOOH)

Watkins, Rhyadd ; Weiss, Dominik ; Dubbin, William ; Peel, Kate ; Coles, Barry and Arnold, Tim LU (2006) In Journal of Colloid and Interface Science 303(2). p.639-646
Abstract

This study reports thermodynamic and kinetic data of Sb(III) adsorption from single metal solutions onto synthetic aqueous goethite (α-FeOOH). Batch equilibrium sorption experiments were carried out at 25 °C over a Sb:Fe molar range of 0.005-0.05 and using a goethite concentration of 0.44 g Fe/L. Experimental data were successfully modelled using Langmuir (R2 ≥ 0.891) and Freundlich (R2 ≥ 0.990) isotherms and the following parameters were derived from triplicate experiments: Kf = 1.903 ± 0.030 mg / g and 1 / n = 0.728 ± 0.019 for the Freundlich model and b = 0.021 ± 0.003 L / mg and Qmax = 61 ± 8 mg / g for the Langmuir model. The thermodynamic parameters determined were the equilibrium... (More)

This study reports thermodynamic and kinetic data of Sb(III) adsorption from single metal solutions onto synthetic aqueous goethite (α-FeOOH). Batch equilibrium sorption experiments were carried out at 25 °C over a Sb:Fe molar range of 0.005-0.05 and using a goethite concentration of 0.44 g Fe/L. Experimental data were successfully modelled using Langmuir (R2 ≥ 0.891) and Freundlich (R2 ≥ 0.990) isotherms and the following parameters were derived from triplicate experiments: Kf = 1.903 ± 0.030 mg / g and 1 / n = 0.728 ± 0.019 for the Freundlich model and b = 0.021 ± 0.003 L / mg and Qmax = 61 ± 8 mg / g for the Langmuir model. The thermodynamic parameters determined were the equilibrium constant, Keq = 1.323 ± 0.045, and the Gibb's free energy, Δ G0 = - 0.692 ± 0.083 kJ / mol. The sorption process is very fast. At a Sb:Fe molar ratio of 0.05, 40-50% of the added Sb is adsorbed within 15 min and a steady state is achieved. The experimental data also suggest that desorption can occur within 24 h of reaction due to the oxidation of Sb(III) on the goethite surface. Finally, calculated pH of the aqueous solution using MINTEQ2 agrees well with the measured pH (3.9 ± 0.7; n = 30). At pH 4, the dominant Sb species in solution are Sb(OH)3 and HSbO2 which both likely adsorb as inner sphere complexes to the positively charged goethite surface.

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author
; ; ; ; and
publishing date
type
Contribution to journal
publication status
published
keywords
Adsorption, Goethite, Isotherms, Kinetics, Sb(III), Sb(V), Speciation, Thermodynamics
in
Journal of Colloid and Interface Science
volume
303
issue
2
pages
8 pages
publisher
Elsevier
external identifiers
  • pmid:16989849
  • scopus:33749617709
ISSN
0021-9797
DOI
10.1016/j.jcis.2006.08.044
language
English
LU publication?
no
id
aea82519-3ad6-4f05-af62-e3dcfb0e27c0
date added to LUP
2024-10-22 10:22:28
date last changed
2025-01-14 18:35:47
@article{aea82519-3ad6-4f05-af62-e3dcfb0e27c0,
  abstract     = {{<p>This study reports thermodynamic and kinetic data of Sb(III) adsorption from single metal solutions onto synthetic aqueous goethite (α-FeOOH). Batch equilibrium sorption experiments were carried out at 25 °C over a Sb:Fe molar range of 0.005-0.05 and using a goethite concentration of 0.44 g Fe/L. Experimental data were successfully modelled using Langmuir (R<sup>2</sup> ≥ 0.891) and Freundlich (R<sup>2</sup> ≥ 0.990) isotherms and the following parameters were derived from triplicate experiments: K<sub>f</sub> = 1.903 ± 0.030 mg / g and 1 / n = 0.728 ± 0.019 for the Freundlich model and b = 0.021 ± 0.003 L / mg and Q<sub>max</sub> = 61 ± 8 mg / g for the Langmuir model. The thermodynamic parameters determined were the equilibrium constant, K<sub>eq</sub> = 1.323 ± 0.045, and the Gibb's free energy, Δ G<sup>0</sup> = - 0.692 ± 0.083 kJ / mol. The sorption process is very fast. At a Sb:Fe molar ratio of 0.05, 40-50% of the added Sb is adsorbed within 15 min and a steady state is achieved. The experimental data also suggest that desorption can occur within 24 h of reaction due to the oxidation of Sb(III) on the goethite surface. Finally, calculated pH of the aqueous solution using MINTEQ2 agrees well with the measured pH (3.9 ± 0.7; n = 30). At pH 4, the dominant Sb species in solution are Sb(OH)<sub>3</sub> and HSbO<sub>2</sub> which both likely adsorb as inner sphere complexes to the positively charged goethite surface.</p>}},
  author       = {{Watkins, Rhyadd and Weiss, Dominik and Dubbin, William and Peel, Kate and Coles, Barry and Arnold, Tim}},
  issn         = {{0021-9797}},
  keywords     = {{Adsorption; Goethite; Isotherms; Kinetics; Sb(III); Sb(V); Speciation; Thermodynamics}},
  language     = {{eng}},
  month        = {{11}},
  number       = {{2}},
  pages        = {{639--646}},
  publisher    = {{Elsevier}},
  series       = {{Journal of Colloid and Interface Science}},
  title        = {{Investigations into the kinetics and thermodynamics of Sb(III) adsorption on goethite (α-FeOOH)}},
  url          = {{http://dx.doi.org/10.1016/j.jcis.2006.08.044}},
  doi          = {{10.1016/j.jcis.2006.08.044}},
  volume       = {{303}},
  year         = {{2006}},
}