A new bioinorganic process for the remediation of Cr(VI)

Palladised biomass of Desulfovibrio desulfuricans ATCC 29577 (bio-Pd(0)) effected reduction of Cr(VI) to Cr(III) under conditions where biomass alone or chemically-prepared Pd(0) were ineffective. Reduction of 500 mumol dm(-3) Cr(VI) by 0.4 mg cm(-3) bio-Pd(0) (Pd:biomass ratio of 1: 1) was achieved from 1 mol dm(-3) formate/acetate buffer at pH 1-7 at room temperature; the optimum pH was 3.0. The ratio of mass of Pd: dry mass of biomass, and the need for finely ground bio-Pd(0) were important parameters for optimal Cr(VI) reduction, with a ratio of 1:1 giving 100% reduction of 500 mumol dm(-3) Cr(VI) within 6 h at room temperature, decreasing to 30 min following heat treatment of the Pd(0)-loaded biomass. The reduced Cr was recovered quantitatively as soluble Cr(III) at pH 3.0 with no poisoning of the bioinorganic catalyst with respect to continued reduction of Cr(VI). (C) 2002 Society of Chemical Industry.