Iron(III)‐Complexes Engaged in the Biochemical Processes in Seawater. II. Voltammetry of Fe(III)‐Malate Complexes in Model Aqueous Solution |
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| Authors: | Petra Vukosav Vladislav Tomišić Marina Mlakar |
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| Affiliation: | 1. Rueer Bo?kovi? Institute, Department for Marine and Environmental Research, Bijeni?ka st. 54, P.?O. Box 180, 10000?Zagreb, Croatia;2. Laboratory of Physical Chemistry, Faculty of Science, University of Zagreb, Horvatovac st. 102a, 10000?Zagreb, Croatia. |
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| Abstract: | Characteristics of iron(III) complexes with malic acid in 0.55 mol L?1 NaCl were investigated by voltammetric techniques. Three iron(III)‐malate redox processes were detected in the pH range from 4.5 to 11: first one at ?0.11 V, second at ?0.35 V and third at ?0.60 V. First process was reversible, so stability constants of iron(III) and iron(II) complexes were calculated: log K1(FeIII(mal))=12.66±0.33, log β2(FeIII(mal)2)=15.21±0.25, log K1(FeII(mal))=2.25±0.36, and log β2(FeII(mal)2)=3.18±0.32. In the case of second and third reduction process, conditional cumulative stability constants of the involved complexes were determined using the competition method: log β(Fe(mal)2(OH)x)=15.28±0.10 and log β(Fe(mal)2(OH)y)=27.20±0.09. |
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| Keywords: | Iron(III) Malic acid Voltammetry Iron(III)‐malate complexes UV‐Vis spectrophotometry |
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