Synthesis and Characterization of Ferrate(VI) Alkali Metal by Electrochemical Method

Abstract

This works aims at preparing at room stable Na 2 FeO 4 and tracking its degradation over time. The synthetic, during this step, was carried out by electrochemical method. The latter was given maximum focus because of its simplicity and the high degree of purity of the resulting product with respect to wet and dry method. This paper reviews the development of the electrochemical method applied to the synthesis of stable at room Na 2 FeO 4 , optimizing the parameters impacting the performance of the oxidation of iron(II) in to iron(VI) in alkaline NaOH, saturated at a temperature of 61˚C and a current density of 1.4 A/dm 2 , in order to simplify the synthesis process, to minimize the cost and to improve the production of iron(VI) to meet the growing demand of ferrate(VI) useful for water treatment. The supervision of the degradation of synthesized Na 2 FeO 4 shows its stability over a period of 10 months, which makes storage and transport easier. The phases obtained were characterized by IR spectrometry, X-ray, Mössbauer, spectroscopy and thermogravimeric analysis.

The History and the Current Revival of the Oxo Chemistry of Iron in its Highest Oxidation States: FeVI – FeVIII

“…Sodium ferrate(VI) , Na 2 [FeO 4 ], even though readily available in alkaline aqueous solution through all dry and wet or electrochemical processes, is not accessible in pure crystalline form by the conventional methods (precipitation from water or other solvents). Most preparations yield severely contaminated solid products . Pure polycrystalline samples were first obtained by M. Malchus and M. Jansen : A column or a batch of an acidic ion exchange resin was loaded with NaOH and treated with an aqueous solution of K 2 [FeO 4 ] (2.5 × 10 –2 m ) at 0 °C for short periods of time.…”

“…Generation of ferrate(VI) solutions by electrosynthesis . The red color of [FeO 4 ] 2– is developed in the anolyte.…”

“…The sample is also reported to release water at 100 °C and to undergo an endothermic loss of oxygen between 210 and 310 °C (TGA). However, the quality of these samples is unknown and the results are at variance with observations with pure samples , …”

Desalination of Water Using ZVI (Fe0)

“…Ferrate(IV) salts form at temperatures of <30 °C [251,252] , and the current efficiency increases as the carbon content of the Fe increases, e.g., a current efficiency of >70% applies when the Fe contains >0.9% C [252]. The formation of the ferrate salt is facilitated by the presence of ClO [253]). The ferrate formation is facilitated by the analyte (pore water) containing >0.02 wt % Cl − , and is optimized by a weight ratio in the pore waters of NaOH:NaCl (or OH:Cl) of between 25:1 and 5000:1 [254].…”

An Overview on Production and Applications of Ferrate(VI)

“…For example, in some cases, the maximum allowed temperature was 60°C. Increasing the electrolysis interval can also increase the interval for reaction, which would ultimately increase the efficiency (30). Basic principles of ferrate(VI) are shown in the following equations:…”