Modeling the aqueous reaction kinetics of estriol with ferrate

Abstract

In this study the aqueous oxidation kinetics of estriol (E3) by potassium ferrate (K₂FeO₄), a chemical for its strong oxidizing power and for producing a coagulant from its reduced state (i.e. Fe(III)), was evaluated in the range of pH 8-12 with different molar ratios of the reactants. As the degree of Fe(VI) protonation varies with the solution pH, it was found that a first order model was not suitable to describe the oxidation reaction. This paper describes a theoretical representation that closely models the reaction kinetics of E3 and ferrate. From this modeling, the reaction rates of HFe$O_4^{-}$and Fe$O_4^{2-}$with E3 have been determined. The results show that the reactivity of HFe$O_4^{-}$ with dissociated and undissociated E3 is greater than that of Fe$O_4^{2-}$, and that E3 is more reactive in its dissociated state.

Keywords

ferrate / estriol / endocrine disruptor / kinetics / oxidation

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Acknowledgements

The authors are grateful for the financial support of National Key Technology R&D Program in the 11th Five year Plan of China(2006BAJ08B06), National Important Project (2008ZX07421-002), State Key Laboratory of Pollution Control and Resource Reuse Project (PCRRF08005), Shanghai Science and Technology Foundation “Innovation Plan of 2007” (No. 072312001) and the Research Committee of the Hong Kong Polytechnic University in providing a Ph.D scholarship for Cong Li and the China Postdoc Foundation.

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