Sr diffusion and reaction within Fe oxides: Evaluation of the rate-limiting mechanism for sorption
Journal Article
·
· Journal of Colloid and Interface Science
- New Jersey Inst. of Tech., Newark, NJ (United States). Dept. of Civil and Environmental Engineering
- Illinois Inst. of Tech., Chicago, IL (United States). Pritzker Dept. of Environmental Engineering
Sorption studies were conducted to study intraparticle diffusion of strontium in amorphous iron oxide. Oxides of manganese and especially iron often control contaminant sorption in the subsurface environment. In the two-step sorption of inorganics by oxide minerals, the first step is a fast, reversible reaction between the bulk aqueous phase and the adsorbent external surface sites. The second step is a slow process wherein the contaminant at the surface slowly diffuses into the interior of the oxide particle. During intraparticle transport, the contaminant diffuses through micropores along interior surface sites. This configurational surface diffusion is the rate-controlling mechanism in the sorption process. Experimental studies were used to determine adsorbent and sorption characteristics. Ferrihydrite characteristics evaluated were porosity, pore size distribution, site density, size, and shape. Isotherm and constant boundary condition studies were used to observe the sorption process at the external and internal surface sites, respectively. By fitting the diffusion model to experimental data, a value of 4 {times} 10{sup {minus}13} cm{sup 2}/s was found for Sr surface diffusivity. Strontium, the contaminant selected for this study, is a concern at several US Department of Energy facilities. The radioisotope strontium-90 is important due to its prevalence in the environment from anthropogenic sources and its significant toxicity.
- OSTI ID:
- 118828
- Journal Information:
- Journal of Colloid and Interface Science, Journal Name: Journal of Colloid and Interface Science Journal Issue: 1 Vol. 175; ISSN 0021-9797; ISSN JCISA5
- Country of Publication:
- United States
- Language:
- English
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