Aqueous Fe(II)-catalyzed iron oxide recrystallization: Fe redox cycling and atom exchange, mineralogical recrystallization and contributing factor

摘要

Iron (Fe) oxides can rapidly recrystallize in the presence of aqueous Fe(II) (Fe(II)(aq)) under anoxic conditions. Since different Fe oxides have diverse affinities and redox reactivities for metal(loid)s, nutrients, and organic matters, recrystallization of Fe oxides significantly alters their speciation and environmental behavior. Therefore, the major reaction steps, rates, and influencing factors of Fe(II)(aq)-catalyzed recrystallization have gained increasing attention. This paper aims to review the latest advances, especially in redox cycling between Fe(II)(aq) and Fe oxide and in the kinetics of Fe atom exchange. The mineralogical recrystallization pathways and intermediate processes of different Fe oxides when exposed to Fe(II)(aq) are discussed. The influencing factors such as morphological natures of Fe oxides and typical environmental substances governing the kinetics of isotopic exchange between Fe(II)(aq) and Fe oxides are summarized. Several major analytical methodologies in this realm are also illustrated. Finally, some unsolved issues and future research directions in the field of Fe(II)(aq)-catalyzed Fe oxide recrystallization are outlined.

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