title: 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.
authors.affiliation: Laboratory of Microbial Ecology and Technology (LabMET), Ghent University , Coupure Links 653, B-9000 Gent, Belgium.
authors.forename: Simon
authors.initials: S
authors.lastname: De Corte
authors.forename: Tom
authors.initials: T
authors.lastname: Hennebel
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Fitts
authors.forename: Tom
authors.initials: T
authors.lastname: Sabbe
authors.forename: Vitaliy
authors.initials: V
authors.lastname: Bliznuk
authors.forename: Stephanie
authors.initials: S
authors.lastname: Verschuere
authors.forename: Daniel
authors.initials: D
authors.lastname: van der Lelie
authors.forename: Willy
authors.initials: W
authors.lastname: Verstraete
authors.forename: Nico
authors.initials: N
authors.lastname: Boon
mesh_terms: D001673:Biodegradation, Environmental; D002384:Catalysis; D011232:Chemical Precipitation; D004008:Diclofenac / Q000302:isolation & purification; D004785:Environmental Pollutants / Q000302:isolation & purification*; D006046:Gold / Q000737:chemistry*; D054879:Halogenation; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008670:Metals / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010165:Palladium / Q000737:chemistry*; D020592:Shewanella / Q000378:metabolism* / Q000648:ultrastructure; D013997:Time Factors; D014241:Trichloroethylene / Q000302:isolation & purification; D014961:X-Ray Diffraction
chemical_list: D004785:Environmental Pollutants; D008670:Metals; D004008:Diclofenac; D014241:Trichloroethylene; D010165:Palladium; D006046:Gold