The effect of smectite on the corrosion of iron metal
Balko, Barbara A. (Lewis and Clark College. Chemistry Department)
Bossé, Stephanie A. (Lewis and Clark College. Chemistry Department)
Cade, Anne E. (Lewis and Clark College. Chemistry Department)
Jones-Landry, Elise F. (Lewis and Clark College. Chemistry Department)
Amonette, James E. (Pacific Northwest National Laboratory. Fundamental and Computational Sciences Directorate)
Daschbach, John L. (Pacific Northwest National Laboratory. Environmental Molecular Sciences Laboratory)

Data:	2012
Resum:	The combination of zero-valent iron (ZVI) and a clay-type amendment is often observed to have a synergistic effect on the rate of reduction reactions. In the present study, electrochemical techniques were used to determine the mechanism of interaction between the iron (Fe) and smectite clay minerals. Iron electrodes coated with an evaporated smectite suspension (clay-modified iron electrodes, CMIEs) were prepared using five different smectites: SAz-1, SWa-1, STx-1, SWy-1, and SHCa-1. All the smectites were exchanged with Na and one sample of SWy-1 was also exchanged with Mg . Potentiodynamic polarization scans and cyclic voltammograms were taken using the CMIEs and uncoated but passivated Fe electrodes. These electrochemical experiments, along with measurements of the amount of Fe and Fe sorbed in the smectite coating, suggested that the smectite removed the passive layer of the underlying Fe electrode during the evaporation process. Cyclic voltammograms taken after the CMIEs were biased at the active-passive transition potential for varying amounts of time suggested that the smectite limited growth of a passive layer, preventing passivation. These results are attributed to the Brønsted acidity of the smectite as well as to its ability to sorb Fe cations. Oxides that did form on the surface of the Fe in the presence of the smectite when it was biased anodically were reduced at a different electrochemical potential from those that form on the surface of an uncoated Fe electrode under otherwise similar conditions; this difference suggested that the smectite reacted with the Fe / the underlying Fe. No significant correlation could be found between the ability of the smectite to remove the Fe passive film and the smectite type. The results have implications for the mixing of sediments and Fe particles in permeable reactive barriers, underground storage of radioactive waste in steel canisters, and the use of smectite supports in preventing aggregation of nano-sized zero-valent iron.
Drets:	Aquest material està protegit per drets d'autor i/o drets afins. Podeu utilitzar aquest material en funció del que permet la legislació de drets d'autor i drets afins d'aplicació al vostre cas. Per a d'altres usos heu d'obtenir permís del(s) titular(s) de drets.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Clay Barrier ; FeClay Interactions ; Fe Corrosion ; Montmorillonite ; Permeable Reactive Barrier ; Smectite ; Zero-Valent Iron
Publicat a:	Clays and Clay Minerals, Vol. 60, Núm. 2 (2012) , p. 136-152, ISSN 1552-8367

DOI: 10.1346/CCMN.2012.0600204

17 p, 871.8 KB  Accés restringit a la UAB

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