Advances in electrochemical Fe(VI) synthesis and analysis

Abstract

Hexavalent iron species (Fe(VI)) have been known for over a century, and have long-time been investigated as the oxidant for water purification, as the catalysts in organic synthesis and more recently as cathodic charge storage materials. Conventional Fe(VI) syntheses include solution phase oxidation (by hyphchlorite) of Fe(III), and the synthesis of less soluble super-irons by dissolution of FeO 4 2-, and precipitation with alternate cations. This paper reviews a new electrochemical Fe(VI) synthesis route including both in situ and ex situ syntheses of Fe(VI) salts. The optimized electrolysis conditions for electrochemical Fe(VI) synthesis are summarized. Direct electrochemical synthesis of Fe(VI) compounds has several advantages of shorter synthesis time, simplicity, reduced costs (no chemical oxidant is required) and providing a possible pathway towards more electro-active and thermal stable Fe(VI) compounds. Fe(VI) analytical methodologies summarized in this paper are a range of electrochemical techniques. Fe(VI) compounds have been explored as energy storage cathode materials in both aqueous and non-aqueous phase in ''super-iron'' battery configurations. In this paper, electrochemical synthesis of reversible Fe(VI/III) thin film towards a rechargeable super-iron cathode is also summarized.

Removal of selected endocrine disrupting chemicals (EDCs) and pharmaceuticals and personal care products (PPCPs) during ferrate(VI) treatment of secondary wastewater effluents

“…In addition, Fe(VI) salts are costly as their production requires multiple chemical processes and long time synthesis, which has limited its use in water and wastewater treatment applications (Jiang and Lloyd, 2002;Sharma, 2002). But recent development in the in situ production of Fe(VI) using an electrochemical method makes it a promising oxidant for the practical application in water and wastewater treatment plants (Yu and Licht, 2008;Alsheyab et al, 2009;Macova et al, 2009).…”

Kinetics modeling and reaction mechanism of ferrate(VI) oxidation of benzotriazoles

“…Due to its dual functions of an oxidant and a subsequent coagulant/precipitant as ferric hydroxide (Fe(III)) (Jun and Wei, 2002), Fe(VI) is regarded as an environmentally friendly oxidant in water and wastewater treatment process (Jiang and Lloyd, 2002;Sharma, 2002Sharma, , 2010Jiang, 2007). However the instability of Fe(VI) has limited its use in water treatment applications, but recent development in the production of Fe(VI) in situ using the electrochemical method makes it a promising oxidant for the real application of Fe(VI) in water and wastewater treatment plants (Yu and Licht, 2008;Alsheyab et al, 2009;Macova et al, 2009). As the oxidant of iron series, Fenton reactions compose reactions of peroxides with iron ions to form active oxygen species at the low pH of 2.8e3.0 that limit their widespread usage (Pignatello et al, 2006) 2-are the predominant species with the oxidizing power of these oxidants increasing in the order nonprotonated ferrate < monoprotonated ferrate < diprotonated ferrate (Kamachi et al, 2005).…”

Treatment of Combined Sewer Overflows Using Ferrate (VI)

“…The enhanced oxidation properties and unique performance ability brought ferrate (VI) back into attention in late 20 th century. There are three methods for synthesis of ferrate (VI) Tiwari et al, 2005;Yu and Licht, 2008):…”