Inorganic contaminant diffusion and reaction within Fe oxides: Evaluation of the rate limiting process for leaching in subsurface environments

Conference · Fri Nov 01 04:00:00 EST 1996

OSTI ID:395366

Axe, L ^[1]; Anderson, P ^[2]

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1. Argonne National Lab., IL (United States)
2. Illinois Inst. of Tech., Chicago, IL (United States). Pritzker Dept. of Environmental Engineering

Although many models used to describe leaching processes are based on the assumption of a rapid equilibrium between the bulk aqueous and solid phases, they generally have not been successful at simulating contaminant distribution in subsurface environments. This lack of success stems from the failure to consider kinetic aspects of contaminant partitioning. Researchers have found that oxides of manganese and especially iron often control contaminant sorption. 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 sorbed 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. 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. The resulting parameters were used to model strontium and cadmium sorption by iron oxides.

• OSTI ID: 395366
• Report Number(s): CONF-9505206--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ADSORPTION
ADSORPTION ISOTHERMS
CADMIUM
IRON OXIDES
MATHEMATICAL MODELS
PERMEABILITY
PHYSICAL PROPERTIES
SOILS
SORPTIVE PROPERTIES
STRONTIUM