Kinetics and Mechanism of Electron Transfer to Heptavalent Manganese by DL-Aspartic Acid in Alkaline Aqueous and Micellar Media
The kinetics and mechanism of the electron transfer of dl-Aspartic acid (Asp) by Mn (VII) in alkaline medium has been studied spectrophotometrically over the range 2.0≤103[Asp] ≤5.0 mol dm−3; 0.01≤[OH-]≤0.05 mol dm−3; 298≤T≤318 K and I=0.05 mol dm−3 (KNO3). The reaction exhibits first-order dependen...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Hindawi Limited
2013-01-01
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| Series: | Journal of Chemistry |
| Online Access: | http://dx.doi.org/10.1155/2013/724505 |
| Summary: | The kinetics and mechanism of the electron transfer of dl-Aspartic acid (Asp) by Mn (VII) in alkaline medium has been studied spectrophotometrically over the range 2.0≤103[Asp] ≤5.0 mol dm−3; 0.01≤[OH-]≤0.05 mol dm−3; 298≤T≤318 K and I=0.05 mol dm−3 (KNO3). The reaction exhibits first-order dependence in [MnO4-]T but shows fractional-order dependence in both [Asp]T and [OH−]T. The reaction was studied in the presence of sodium dodecyl sulfate (SDS); an increase in the rate with the increase in the micellar concentration was observed. The products were characterized by spectral analysis. A mechanism involving free radicals is proposed. Asp binds MnO4- to form a complex that subsequently decomposes to products. Activation parameters ΔH° (kJ mol−1) and ΔS° (JK−1 mol−1) for the reaction are 5.62 ± 0.35 and −227.65 ± 1.1, respectively. The negative value of ΔS° indicates that oxidation occurs via inner sphere mechanism. |
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| ISSN: | 2090-9063 2090-9071 |