从电子废弃物和稀贵金属溶液中提取钯金.pdf

Abstract Biomass of Desulfovibrio desulfuri- cans was used to recover Au(III) as Au(0) from test solutions and from waste electronic scrap leachate. Au(0) was precipitated extracellularly by a different mechanism from the biodeposi- tion of Pd(0). The presence of Cu2+ (~2000 mg/ l) in the leachate inhibited the hydrogenase- mediated removal of Pd(II) but pre-palladisa- tion of the cells in the absence of added Cu2+ facilitated removal of Pd(II) from the leachate and more than 95% of the Pd(II) was removed autocatalytically from a test solution supple- mented with Cu(II) and Pd(II). Metal recovery was demonstrated in a gas-lift electrobioreactor with electrochemically generated hydrogen, fol- lowed by precipitation of recovered metal under gravity. A 3-stage bioseparation process for the recovery of Au(III), Pd(II) and Cu(II) is proposed. Keywords Desulfovibrio desulfuricans ? Gold recovery ? Palladium recovery ? WEEE scrap Introduction Bioreduction and bioaccumulation of metals are well-documented with respect to the potential for using bioremediation for the treatment of wastes (e.g. see Gadd 1992; Gadd and White 1993; Lloyd 2003; Lloyd et al. 2003, 2005) and recent attention has turned to the biorecovery of precious metals. Silver biorecovery, via the microbial reduction of Ag(I) has been noted, e.g. Fu et al. (2000) reported biosorption of Ag(I) to a Lactobacillus sp. followed by reduction to Ag(0) by an unidentified mechanism, while Klaus et al. (1999) reported the formation of silver nanoparticles in the periplasmic space of Pseudomonas stutzeri. Biorecovery of platinum and palladium species onto biomass components and bacterial cells is also documented. Both metals are biosorbed onto biomass and biopolymer derivatives (e.g. De Vargas et al. 2004; Chassary et al. 2005). With Desulfovibrio desulfuricans uptakes of Pd and Pt of 19% and 9% of the biomass dry weight respectively were recorded at pH 3; some endogenous metal reduction was observed in the absence of a