Transformation of Magnetite to Goethite During Cr(VI) Reduction Under Alkaline pH Conditions
This study investigated Cr(VI) reduction by synthetic magnetite under alkaline pH conditions similar to high level wastes at the Hanford site. Cr(VI) reduction by magnetite is significantly inhibited at alkaline pH, compared to the complete sorption/reduction at acid and neutral pH. This is probably due to (1) trace amounts of O2 in the system which depletes Fe(II) available for Cr(VI) reduction, since O2 is much more reactive than Cr(VI) under high pH conditions and (2) a formation of a passivation layer of maghemite and/or goethite blocking the Fe2+ surface sites in magnetite. Our experiments showed magnetite was indeed transformed into maghemite by a well-known process. However, TEM and XRD analyses showed a prominent goethite phase was also formed and the intensity of goethite peaks in the XRD spectra increased with NaOH concentration. Goethite formation has implications for enhanced removal of metal contaminants in the tank waste through sorption processes.
- Research Organization:
- Ohio State University, Columbus, OH; University of California, Merced, CA (US)
- Sponsoring Organization:
- USDOE Office of Science (SC) (US)
- OSTI ID:
- 826000
- Country of Publication:
- United States
- Language:
- English
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