Effect of aging on reversibility of nickel and lead partitioning to iron oxides
- Clemson Univ., SC (United States)
Hydrous iron oxides can play a significant role in controlling the mobility of trace metals in the environment. Metals adsorbed to or coprecipitated with the poorly-crystalline ferrihydrite may form solid solutions with goethite and hematite as solid aging progresses. This will lead to a fraction of partitioned metal resistant to desorption. The magnitude of this fraction will depend on the extent of metal miscibility (ionic radius) and the stability of the metal-ferrihydrite complex (logK{sup surf}{sub int}). In Fe-Ni and Fe-Pb int binary systems, an apparent miscibility limit is exceeded at (Pb)t = 5x10{sup -4} M and (Fe)t = 0.01 M as measured by increasing (Pb)aq with aging, contrary to the behavior of Ni. Extraction of the solid phase with an acidic oxalate solution to remove ferrihydrite indicates that 70% of (Ni)t is nonreversibly associated with hematite and goethite. However, x-ray diffraction indicates that both Ni and Pb are substituted into these crystalline iron oxides.
- OSTI ID:
- 126401
- Report Number(s):
- CONF-950402--
- Country of Publication:
- United States
- Language:
- English
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