title: Using non-invasive magnetic resonance imaging (MRI) to assess the reduction of Cr(VI) using a biofilm-palladium catalyst.
abstract: Industrial waste streams may contain contaminants that are valuable like Pd(II) and/or toxic and mutagenic like Cr(VI). Using Serratia sp. biofilm the former was biomineralized to produce a supported nanocrystalline Pd(0) catalyst, and this biofilm-Pd heterogeneous catalyst was then used to reduce Cr(VI) to less dangerous Cr(III) at room temperature, with formate as the electron donor. Cr(VI)((aq)) is non-paramagnetic while Cr(III)((aq)) is paramagnetic, which enabled spatial mapping of Cr species concentrations within the reactor cell using non-invasive magnetic resonance (MR) imaging experiments. Spatial reactivity heterogeneities were thus examined. In batch reactions, these could be attributed primarily to heterogeneity of Pd(0) distribution and to the development of gas bubbles within the reactor. In continuous flow reactions, spatial reactivity heterogeneities resulted primarily from heterogeneity of Cr(VI) delivery.
authors.affiliation: Department of Chemical Engineering, University of Cambridge, UK.
authors.forename: D A
authors.initials: DA
authors.lastname: Beauregard
authors.forename: P
authors.initials: P
authors.lastname: Yong
authors.forename: L E
authors.initials: LE
authors.lastname: Macaskie
authors.forename: M L
authors.initials: ML
authors.lastname: Johns
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D002384:Catalysis; D002857:Chromium / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D012705:Serratia / Q000166:cytology* / Q000378:metabolism*; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods
chemical_list: D002857:Chromium; C074702:chromium hexavalent ion; D010165:Palladium