Methodologies for the analytical determination of ferrate(VI): A Review

Abstract

This paper reviewed different analytical techniques to determine concentrations of the environmentally-friendly oxidant ferrate(VI) (Fe^VIO²⁻ ₄, Fe(VI)) anion in solid and solution samples. The techniques included volumetric (chromite and arsenite), electrochemical (cyclic voltammetry and potentiometry), and spectrophotometric methods (Fourier transform infrared, Mössbauer, UV-Visible, 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonate (ABTS), and fluorescence). The importance of the techniques were briefly described. This paper also presented a newly developed method for the determination of low concentrations (0.25 μM) of Fe(VI)) using the reaction between Fe(VI) and iodide (I⁻), which formed the yellowish color of I⁻ ₃ that could be measured spectrophotometrically at 351 nm. The increase in I⁻ ₃ was linear with respect to Fe(VI) added (0.25−76 μM) in buffered solutions at pH 5.5–9.3. The linearity was not affected by the ions present in tap water.

Keywords:

• Ferrate
• colorimetric technique
• electrochemical methods
• Mossbauer spectra

Acknowledgments

V.K. Sharma wishes to acknowledge partial support of NATO Collaborative Linkage Grant (CBP.EAP.CLG.983119). V.K. Sharma also acknowledges the partial support of U.S. National Science Foundation grant (CHE 0706834). Authors wish to thank Dr. Mary Sohn and anonymous reviewers for their comments which improved the paper greatly.