Reduction of Ag(I), Au(III), Cu(II), and Hg(II) by Fe(II)/Fe(III) hydroxysulfate green rust.
Green rusts are mixed Fe(II)/Fe(III) hydroxides that are found in many suboxic environments where they are believed to play a central role in the biogeochemical cycling of iron. X-ray absorption fine structure analysis of hydroxysulfate green rust suspensions spiked with aqueous solutions of AgCH(3)COO, AuCl(n)(OH)(4-n), CuCl(2), or HgCl(2) showed that Ag(I), Au(III), Cu(II), and Hg(II) were readily reduced to Ag(0), Au(0), Cu(0), and Hg(0). Imaging of the resulting solids from the Ag(I)-, Au(III)-, and Cu(II)-amended green rust suspensions by transmission electron microscopy indicated the formation of submicron-sized particles of Ag(0), Au(0), and Cu(0). The facile reduction of Ag(I), Au(III), Cu(II), and Hg(II) to Ag(0), Au(0), Cu(0), and Hg(0), respectively, by green rust suggests that the presence of green rusts in suboxic soils and sediments can have a significant impact on the biogeochemistry of silver, gold, copper, and mercury, particularly with respect to their mobility.
O'Loughlin
Edward J
EJ
Argonne National Laboratory, 9700 South Cass Ave., Argonne, IL 60439-4843, USA. oloughlin@anl.gov
Kelly
Shelly D
SD
Kemner
Kenneth M
KM
Csencsits
Roseann
R
Cook
Russell E
RE
D004577:Electron Probe Microanalysis; D005290:Ferric Compounds / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry*; D008854:Microscopy, Electron; D010084:Oxidation-Reduction
D005290:Ferric Compounds; D005296:Ferrous Compounds; D019216:Metals, Heavy