Influence of the oxidizing species on the reactivity of iron-based Bimetallic reductants.

Anticipating which pollutants are amenable to treatment by iron-based bimetallic reductants requires an understanding of the mechanism(s) driving pollutant reduction. Here, batch studies with six bimetals (Au/Fe, Co/Fe, Cu/Fe, Ni/ Fe, Pd/Fe, and Pt/Fe) and four oxidants (alkyl polyhalides, vinyl polyhalides, alkynes, and water) explored the influence of the electron acceptor on reductant reactivity. Bimetals exhibited disparate reactivity toward some oxidant classes.

Exploring the influence of granular iron additives on 1,1,1-trichloroethane reduction.

Bimetallic reductants are frequently more reactive toward organohalides than unamended iron and can also alter product distributions, yet a molecular-level explanation for these phenomena remains elusive. In this study, surface characterization of six iron-based bimetallic reductants (Au/Fe, Co/Fe, Cu/Fe, Ni/Fe, Pd/Fe, and Pt/Fe) revealed that displacement plating produced a non-uniform overlayer of metallic additive on iron. Batch studies demonstrated that not all additives enhanced rates of 1,1,1-trichloroethane (1,1,1-TCA) reduction nor was there any clear periodic trend in the observed reactivity (Ni/Fe approximately Pd/Fe > Cu/Fe > Co/ Fe > Au/Fe approximately Fe > Pt/Fe).

Influence of copper loading and surface coverage on the reactivity of granular iron toward 1,1,1-trichloroethane.

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 (X-ray 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.