Авторы: Bransfield S., CWIERTNY D., Roberts A.

2006 г.

Env.Sci.Techn.

      Although iron-based bimetallic reductants offer promise in treating organohalides, the influence of additive mass loading and two-dimensional surface coverage on reductant reactivity has not been fully elucidated. In this study we examine 1,1,1-trichloroethane reduction by Cu/Fe bimetals as a function of Cu loading and surface coverage. Information from a suite of complementary techniques (Xray photoelectron spectroscopy, Auger electron spectroscopy, and cross-sectional energy-dispersive X-ray spectroscopy) indicates that displacement plating produces a heterogeneous metallic copper overlayer on iron. The dependence of pseudo-first-order rate constants (kobs values) for 1,1,1-trichloroethane reduction on Cu loading exhibits two distinct regimes. At Cu loadings less than 1 monolayer equivalent (10 ímol Cu/g Fe), a pronounced increase inkobs is associated with a corresponding increase in the twodimensional surfacecoverage of Cu. A weaker dependence of kobs on Cu mass is exhibited at loadings in excess of 1 monolayer equivalent, which we ascribe to an increase in the volume of the metallic overlayer. The observed relationship between kobs and loading suggests that 1,1,1- trichloroethane reduction occurs on the Cu surface rather than at the interface between the Cu overlayer and the iron substrate.

Файл: 628.pdf