Quantitative Analysis of Ferrate(VI) and Its Degradation Products in Electrochemically Produced Potassium Ferrate for Waste Water Treatment

Featured Application Our results demonstrate the easy and accurate control of the amount of active ingredient relative to its degradation product in waste water treatment materials containing ferrate(VI).Abstract Potassium ferrate(VI) (K2FeO4) as a particularly strong oxidant represents an effective and environmentally friendly waste water treatment material. When produced by anodic oxidation in highly alkaline aqueous solution, the K2FeO4 product is separated and sealed in inert plastic bags with the retention of some liquid phase with high pH. This method proved to be excellent for long-term storage at moderately low temperature (5 degrees C) for industrial applications. It is still imperative to check the ferrate(VI) content of the product whenever it is to be used. Fe-57 M & ouml;ssbauer spectroscopy is an excellent tool for checking the ratio of ferrate(VI) to the degradation product iron(III) in a sample. For this purpose, normally the spectral areas of the corresponding subspectra are considered; however, this approximation neglects the possible differences in the corresponding M & ouml;ssbauer-Lamb factors. In this work, we have successfully determined the M & ouml;ssbauer-Lamb factors for the ferrate(VI) and for the most common iron(III) degradation products observed. We have found superparamagnetic behavior and low-temperature phase transformation for another iron(III) degradation product that made the determination of the M & ouml;ssbauer-Lamb factors impossible in that case. The identities of a total of three different iron(III) degradation products have been confirmed.