pH-dependence of selenate removal from liquid phase by reductive Fe(II)–Fe(III) hydroxysulfate compound, green rust

The reduction of selenium(IV) by hydrogen sulfide in aqueous solutions

“…Many authors (Myneni et al, 1997;Scheinost et al, 2008;Chen et al, 2009) questioned the ability of Fe 2+ to reduce Se(IV) in aqueous solutions because of similar standard potentials for the couples Fe 3+ /Fe 2+ (E 0 = +0.771 V) and HSeO 3 À / Se(0) (E 0 = +0.774 V). Indeed Fe(II) adsorbed by clay minerals such as montmorillonite or calcite or present in a number of solids like siderite, mackinawite, magnetite, pyrite, triolite, green rust was found to be able to reduce selenite (Refait et al, 2000;Charlet et al, 2007;Scheinost et al, 2008;Hayashi et al, 2009;Chakraborty et al, 2010). Possible reductants for Se(IV) also include zerovalent iron (Olegario et al, 2010), sodium dithionite (Geoffroy and Demopoulos, 2009), ascorbic acid (Shaker, 1996) and iodide (Ericzon et al, 1990).…”

Neptunyl (Np) interaction with green rust,

“…Green rust is known to react with a number of redox sensitive species, including chromium, uranium, selenium and technetium (Roh et al, 2000b;Bond and Fendorf, 2003;Dodge et al, 2003;O'Loughlin et al, 2003a;Pepper et al, 2003;Legrand et al, 2004;Skovbjerg et al, 2006;Hayashi et al, 2009). Studies of the reaction between GR SO 4 and chromate (CrO 4 2À ) showed that the reaction mechanism depended on the geometry of the anion (Skovbjerg et al, 2006).…”

Reduction of selenite and selenate on anoxically corroded iron and the synergistic effect of uranyl reduction

“…This can be rationalized by the observations that magnetite is among the iron oxides formed when selenate is reduced by Fe(II)/(III) oxyhydroxides [7,39], so that the surface in the present case repassivates itself towards selenate immobilization by reformation of a magnetite layer. Maghemite, c-Fe 2 O 3 , another candidate passifying oxide which can form from the topotactic oxidation of the Fe(II) in magnetite was also observed by Raman spectroscopy in sample 250SeVI/420U (Fig.…”