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 HFeO_4^{-}and FeO_4^{2-}with E3 have been determined. The results show that the reactivity of HFeO_4^{-} with dissociated and undissociated E3 is greater than that of FeO_4^{2-}, and that E3 is more reactive in its dissociated state.

Key words： ferrate; estriol; endocrine disruptor; kinetics; oxidation

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.

References

1 Fry D M. Reproductive effects in birds exposed to pesticides and industrial chemicals. Environ Sci Technol, 1995, 311: 65-171

2 Sumpter J P. Feminized responses in fish to environmental estrogens. Toxicol Lett, 1995, 82-83: 737–742

3 Jiang J Q, Lloyd B. Progress in the development and use of ferrate(VI) salt as an oxidant and coagulant for water and wastewater treatment. Wat Res, 2002, 36: 1397-1408

4 Sharma V K, Rivera W, Joshi V N, Millero F J, Oconnor D. Ferrate(VI) oxidation of thiourea. Environ Sci Technol, 1999, 33: 2645-2650

5 Jiang J Q, Wang S. Enhanced coagulation with potassium ferrate(VI) for removing humic substances. Environ Eng Sci, 2003, 20: 627-635

6 Huang H, Sommerfeld D, Dunn B C, Eyring E M, Lioyd C R. Ferrate(VI) oxidation of aqueous phenol: kinetics and mechanism. J Phys Chem A, 2001, 105: 3536-3541

7 Bielski B H J, Thomas M J. Studies of hypervalent iron in aqueous solutions. 1. readiation induced reduction of iron(VI) to iron(V) by CO2-. J Am Chem Soc, 1987, 109: 7761-7764

8 Li C, Li X Z, Graham N. A study of the preparation and reactivity of potassium ferrate. Chemosphere, 2005, 61: 537-543

9 Jiang J Q, Lloyd B, Grigore L. Preparation and evaluation of potassium ferrate as an oxidant and coagulant for potable water treatment. Environ Eng Sci, 2001, 18: 323-328

10 Licht S, Naschitz V, Halperin L, Halperin N, Lin L, Chen J J, Ghosh S, Liu B. Analysis of ferrate (VI) compounds and super-iron Fe(VI) battery cathodes: FTIR, ICP, titrimetric, XRD, UV/VIS, and electrochemical characterization. J Power Sources, 2001, 101: 167-176

11 Sharma V K. Potassium ferrate(VI): an environmentally friendly oxidant. Adv Environ Res, 2002, 6: 143-156

12 Graham N, Jiang C C, Li X Z, Jiang J Q, Ma J. The influence of pH on the degradation of phenol and chlorophenols by potassium ferrate. Chemosphere, 2004, 56: 949-956

13 Hoigné J, Bader H. Rate constants of reactions of ozone with organic and inorganic compounds in water. II: dissociating organic compounds. Water Res, 1983, 17: 185-194

14 Langlais B, Reckhow D A, Brink R B, eds. Ozone in water treatment: application and engineering. New York: Lewis Publishers, 1991, 43-45

15 Pinkston K E, Sedlak D L. Transformation of aromatic ether and amine containing pharmaceuticals during chlorine disinfection. Environ Sci Technol, 2004, 38: 4019-4025

16 Li C, Li X Z, Graham N, Gao N Y. The aqueous degradation of bisphenol a and steroid estrogens by ferrate. Water Research, 2008, 42(1-2): 109-120