Specific adsorption of halogen anions on hydrous γ-Al2O3 |
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Authors: | W Szczepaniak H Ko
cielna |
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Institution: | Department of Analytical Chemistry, Faculty of Chemistry, Adam Mickiewicz University, ul. Grunwaldzka 6, 60-780, Poznan, Poland |
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Abstract: | The paper reports results of a study on the specific adsorption of F−, Cl−, Br−, I−, ClO3−, BrO3−, IO3− and IO4− on hydrous γ-Al2O3. The isotherms of the anion adsorption and the adsorption dependencies on pH and the ionic strength of the solution have been determined under the equilibrium conditions. According to the degree of affinity to γ-Al2O3, the anions can be ordered as: I−3− −−3−3−4−−. It has been established that the sorption of IO4− and F− involves the formation of surface complexes in the inner co-ordination sphere, whereas that of Cl−, Br−, I−, ClO3−, BrO3− and IO3− takes place through formation of ion pair complexes in the outer co-ordination sphere. In the dynamic system, the exchange isoplanes and elution curves have been determined for selected anions on columns filled with Al2O3. It has been shown that γ-Al2O3 can be used for isolation and concentration of IO3− from natural waters in order to decrease the limit of the ions determination to 2 μg l−1. Using differential pulse voltammetry (DPV), after isolation and concentration on γ-Al2O3, the content of iodates has been determined in mineral, marine and tap water doped with these ions. |
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Keywords: | Hydrous γ-Al2O3 Anion adsorption Differential pulse voltammetry |
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