Potentiometric and electrokinetic signatures of iron(II) interactions with (a,y)-Fe2O3

Journal Article · Fri May 29 00:00:00 EDT 2015 · Physical Chemistry Chemical Physics. PCCP (Print)

DOI:https://doi.org/10.1039/C5CP03106K· OSTI ID:1244818

Toczydlowska, Diana; Kedra-Krolik, Karolina; Nejbert, Krzysztof; Preocanin, Tajana; Rosso, Kevin M.; Zarzycki, Piotr P.

The role of surface electrostatics on the reductive dissolution of iron (III) oxides is poorly understood, despite its importance in controlling the amount of mobilized iron. We report the potentiometric titration of the a; y -Fe2O3 oxides exposed to reductants and complexing ligands (Fe(II), ascorbate, oxalate, malonate). We monitored in situ surface and potentials, the ratio of mobilized ferric to ferrous ions, and periodically analyzed nanoparticle crystal structure using X-ray diffraction. We found that addition of Fe2+ ions produces a response consistent with the iron solubilityactivity curve, whereas the presence of ascorbate significantly decreases the amount of mobilized Fe(III) due to reduction to Fe(II). In addition, XRD analysis proved that y-Fe2O3 particles remain structurally unchanged along the titration pathway despite iron cycling between aqueous and solid reservoirs. Our studies, suggest that the surface redoxactivity of iron oxides is primarily governed by the balance between Fe(III) and Fe(II) ions in aqueous phase, which may be easily altered by complexing and reducing agents.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1244818
• Report Number(s): PNNL-SA-103997; KC0302060
• Journal Information: Physical Chemistry Chemical Physics. PCCP (Print), Vol. 17, Issue 39; ISSN 1463-9076
• Publisher: Royal Society of Chemistry
• Country of Publication: United States
• Language: English