Mao,Y., Pham,A.N.P., Rose,A.L. and Waite,T.D.(2011): Influence of phosphate on the oxidation kinetics of nanomolar Fe(II) in aqueous solution at circumneutral pH. Geochimica et Cosmochimica Acta, 75, 4601-4610.

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wAbstract
@The oxygenation kinetics of nanomolar concentrations of Fe(II) in aqueous solutions have been studied in the absence and presence of millimolar concentrations of phosphate over the pH range 6.0-7.8. At each phosphate concentration investigated, the overall oxidation rate constant varied linearly with pH, and increased with increasing phosphate concentration. A model based on equilibrium speciation of Fe(II) was found to satisfactorily explain the results obtained. From this model, the rate constants for oxygenation of the Fe(II)-phosphate species FeH2PO4+, FeHPO4 and FePO4- have been determined for the first time. FePO4- was found to be the most kinetically reactive species at circumneutral pH with an estimated oxygenation rate constant of (2.2}0.2)~10 M-1 s-1. FeH2PO4+ and FeHPO4 were found to be less reactive with oxygen, with rate constants of (3.2}2)~10-2 M-1 s-1 and (1.2}0.8)~10-1 M-1 s-1, respectively.x

1. Introduction
2. Materials and methods
@2.1. Reagent preparation
@2.2. Fe(II) analysis
@2.3. Fe(II) oxidation experiments
@2.4. Fe(II) speciation calculations
@2.5. Estimation of individual oxidation rate constants
3. Results and discussion
@3.1. Overall Fe(II) oxidation rate constants
@3.2. The speciation model
@3.3. Evaluation of rate constants in the context of Marcus Theory
4. Conclusions
Acknowledgments
Appendix A. Supplementary data
References


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