Biosupported Bimetallic Pd-Au Nanocatalysts for Dechlorination of Environmental Contaminants

摘要

Biologically produced monometallic palladium nanoparb-cles (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 nanopartide catalysts. The obtained catalysts were tested for the dechlorination of diclofe-nac 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 Shtwanella oneedensis in the presence of H2 the resulting cell-associated bimetallic nanoparticles (bio-Pd/Au) were able to dehalo-genate 78% of the initially added diclofenac after 24 h; in comparison, no dehalogenation was observed using monometallic bio-Pd or bio-Ail. Other catalyst-synthesis strategies did not show improved dehalogenarJon 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 redaction of Pd and Au supported on cells of S. otuidatsis 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-catarysts can be improved by coprecipitation with An.