Journal
GEODERMA
Volume 213, Issue -, Pages 10-14Publisher
ELSEVIER
DOI: 10.1016/j.geoderma.2013.07.022
Keywords
Cr(III)-cit; Cr(III)-tar; Cr(VI); Oxidation; delta-MnO2
Categories
Funding
- Fundamental Research Funds for the Central Universities [KYZ201124]
- Science and Technology Program of ChangZhou (Applied Basic Research) [CJ20125003]
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Cr(III)-cit and Cr(III)-tar were synthesized and purified, and then their stability in the presence of delta-MnO2 was further investigated in batch experiments under different conditions to predict the potential oxidation behaviors of Cr(III)-organic acid complexes in the environment. The results indicated that although the rates and extents of Cr(III)-cit and Cr(III)-tar oxidation by delta-MnO2 were much lower than those of aqueous Cr(III), Cr(VI) could be gradually released through the whole reaction. The oxidations of Cr(III)-cit and Cr(III)-tar were affected by the initial concentrations of delta-MnO2, pH and co-existing ions. Lower pH and higher concentrations of delta-MnO2 markedly enhanced the production of Cr(VI). Ammonium ions significantly improved the oxidation of Cr(III)-cit and Cr(III)-tar, but phosphate ions demonstrated an opposite effect due to the formation of more stable CrPO4. The oxidation process of Cr(III)-cit and Cr(III)-tar by delta-MnO2 can be divided into two phases. At the initial phase, a relatively rapid reaction obeyed the first-order model, and then a zero-order one was followed. It was observed that in all the cases the extent of Cr(III)-cit oxidation was lower than that of Cr(III)-tar. Thus, it was concluded that the stability of Cr(III)-cit was higher than that of Cr(III)-tar. (C) 2013 Elsevier B.V. All rights reserved.
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