Mechanistic investigations of Se(VI) treatment in anoxic groundwater using granular iron and organic carbon: An EXAFS study

Reductive removal of selenate by zero-valent iron: The roles of aqueous Fe2+ and corrosion products, and selenate removal mechanisms

“…Increased selenate and Fe 2þ loadings and an elongated reaction time were used to prepare XPS samples, which might result in transformation of more adsorbed selenite and elemental Se to selenide. In the past, Se 0 and/or FeSe were also detected during selenate reduction by ZVI without Fe 2þ supplied externally (Gibson et al, 2012;Klas and Kirk, 2013;Yoon et al, 2011).…”

“…However, the iron surface passivation by ferric coating is the biggest challenge for its long-term application. It has also been proved that ZVI (Yoon et al, 2011;Gibson et al, 2012) or nano-ZVI (Olegario et al, 2010) was effective for Se VI removal from wastewater by reducing to more adsorptive Se IV and/or to insoluble Se species (i.e., Se 0 , Se ÀI and Se ÀII ). However, most of previous studies primarily focused on the effects of co-existent ions, contaminants, and the operational parameters such as pH, dissolved oxygen and reagent concentration (Klas and Kirk, 2013;Puranen et al, 2009).…”

Efficient selenate removal by zero-valent iron in the presence of weak magnetic field

“…Depending on its concentration, selenium can act as an essential micro-nutrient protecting against reactive oxygen species damages, or as a toxic compound [2]. Se pollution is a worldwide problem and mainly originates from agricultural practices, manufacture processes, coal combustion and mining processes [3].…”

“…However, the iron filings or microscale iron powder had low reactivity toward Se(VI) removal. A huge dosage of micron-sized ZVI (50-100 g L À1 ) was necessary to sequester Se(VI) and the removal capacity of ZVI for Se(VI) was very low [2,10]. To improve the removal rate of Se(VI) by ZVI, nano-sized ZVI (nZVI) and NiFe bimetal were used [11].…”

Bentonite modification with hexadecylpyridinium and aluminum polyoxy cations and its effectiveness in Se(IV) removal

“…Selenite, selenate and selenomethionine are among the most acutely toxic selenium compounds (SCF/CS/NUT/UPPLEV/25 2000). The oxidized forms of Se, the selenite and selenate are the most soluble and predominating forms in natural water systems where they are more available for plants and potentially toxic to aquatic organisms (Gibson et al, 2012;Mechora et al, 2011). For these reasons, selenium should be removed from the environment.…”