Dehalogenation of chlorinated aromatic compounds using a hybrid bioinorganic catalyst on cells of Desulfiovibrio desulfuricans

A novel bioinorganic catalyst was obtained via reduction of Pd(II) to Pd-0 on to the surface of cells of Desufovibrio desulfuricans at the expense of H-2 Palladised biomass, supplied with formate or H-2 as an electron donor, catalysed the dehalogenation of 2-chlorophenol and polychlorinated biphenyls. In the example of 2,3,4,5-tetrachlorobiphenyl, the bioinorganic catalyst promoted a rate of chloride release of 9.33 +/- 0.17 nmol min(-1) mg(-1) and only similar to5% of this value was obtained using chemically reduced or commercially available Pd-0. In the case of 2,2',4,4',6,6'-hexachlorobiphenyl the rate was more than four orders of magnitude faster than the degradation reported using a sulfidogenic culture. Negligible chloride release occurred from any of the chloroaromatic compounds using biomass alone, or from palladised biomass challenged with hexane carrier solvent only. Analysis of the spent solution showed that in addition to catalysis of reductive dehalogenation the new material was able to remove very effectively the organic residua, with neither any PCB nor any breakdown products identifiable by GC/MS.