Sulphate-reducing bacteria, palladium and the reductive dehalogenation of chlorinated aromatic compounds

The surfaces of cells of Desulfovibrio desulfuricans, Desulfovibrio vulgaris and a new strain, Desulfovibrio sp. 'Oz-7' were used to manufacture a novel bioinorganic catalyst via the reduction of Pd(II) to Pd(0) at the cell surface using hydrogen as the electron donor. The ability of the palladium coated (palladised) cells to reductively dehalogenate chlorophenol and polychlorinated biphenyl species was demonstrated. Dried, palladised cells of D. desulfuricans, D. vulgaris and Desulfovibrio sp. 'Oz-7' were more effective bioinorganic catalysts than Pd(II) reduced chemically under H2 or commercially available finely divided Pd(0). Differences were observed in the catalytic activity of the preparations when compared with each other. Negligible chloride release occurred from chlorophenol and polychlorinated biphenyls using biomass alone.