X-RAY PHOTOELECTRON-SPECTRA OF THE PALLADIUM-IRON BIMETALLIC SURFACE USED FOR THE RAPID DECHLORINATION OF CHLORINATED ORGANIC ENVIRONMENTALCONTAMINANTS
R. Muftikian et al., X-RAY PHOTOELECTRON-SPECTRA OF THE PALLADIUM-IRON BIMETALLIC SURFACE USED FOR THE RAPID DECHLORINATION OF CHLORINATED ORGANIC ENVIRONMENTALCONTAMINANTS, Environmental science & technology, 30(12), 1996, pp. 3593-3596
Palladized iron (Pd/Fe) has been successfully used for the rapid dechl
orination of organic environmental contaminants in aqueous solutions.
We have investigated the nature of the Pd/Fe surface by X-ray photoele
ctron spectroscopy. Our results indicate that the reactive Pd/Fe surfa
ce is formed by the stepwise reduction of Pd(IV) in solution to Pd(II)
, which replaces protons on the hydroxylated iron oxide surface and fo
rms Pd(II)-0-Fe bonds. These-bonds are unstable and collapse spontaneo
usly to yield the reactive palladized iron in which the palladium is i
n the elemental state. Prolonged exposure of this Pd/Fe surface to a s
aturated solution of aqueous TCE results in the growth of the hydroxyl
ated iron oxide film that deactivates the Pd/Fe surface. The thick hyd
roxylated iron oxide film can be removed, and the original activity of
the Pd/Fe surface can be restored by washing the surface with a dilut
e acid solution.