Biosupported Bimetallic Pd–Au Nanocatalysts for Dechlorination of Environmental Contaminants

Abstract

Biologically produced monometallic palladium nanoparticles (bio-Pd) have been shown to catalyze the dehalogenation of environmental contaminants, but fail to efficiently catalyze the degradation of other important recalcitrant halogenated compounds. This study represents the first report of biologically produced bimetallic Pd/Au nanoparticle catalysts. The obtained catalysts were tested for the dechlorination of diclofenac and trichlorethylene. When aqueous bivalent Pd(II) and trivalent Au(III) ions were both added to concentrations of 50 mg L(-1) and reduced simultaneously by Shewanella oneidensis in the presence of H(2), the resulting cell-associated bimetallic nanoparticles (bio-Pd/Au) were able to dehalogenate 78% of the initially added diclofenac after 24 h; in comparison, no dehalogenation was observed using monometallic bio-Pd or bio-Au. Other catalyst-synthesis strategies did not show improved dehalogenation of TCE and diclofenac compared with bio-Pd. Synchrotron-based X-ray diffraction, (scanning) transmission electron microscopy and energy dispersive X-ray spectroscopy indicated that the simultaneous reduction of Pd and Au supported on cells of S. oneidensis resulted in the formation of a unique bimetallic crystalline structure. This study demonstrates that the catalytic activity and functionality of possibly environmentally more benign biosupported Pd-catalysts can be improved by coprecipitation with Au.

Engineering tailored nanoparticles with microbes: quo vadis?

“…In this study, the authors report the production of bimetallic nanoparticle catalysts, which were tested for dechlorination of diclofenac and trichloroethylene. (Reprinted with permission from Ref . Copyright 2011 American Chemical Society); (c) Field emission scanning electron microscopy (FE‐SEM) image of Micrococcus lylae bacteria used as biotemplates; (d) Morphology of a hierarchical, flower‐like, porous‐Co 3 O 4 nanostructure grown on a bacterial template.…”

Iron-Based Nanoparticles for Toxic Organic Degradation: Silica Platform and Green Synthesis

“…Smaller Pd particles have been synthesized by other methods, such as the use of polyligand stabilizers and ascorbic acid reduction, 45 as well as the in vivo synthesis of bio-Pd. 46 However, this simple method yields stable, small Pd or Fe/Pd NP. TEM of the ascorbic acid-synthesized particles at lower pH indicates the unusual growth of crystals with agglomerate diameter ~100 nm (Figure 7).…”

Optical Elemental Analysis of Metals Using Shewanella oneidensis

“…These results implied that the formation of NPs on the bacterial surface was controlled by the reduction rate and incubation conditions. 16,17 To apply S. oneidensis for elemental analysis, a better understanding of the reactivity of metal species and the stability of metal NPs, based on standard electrode potentials, nanoparticle forming abilities, and incubation conditions, is required.…”