title: Microbial reduction of Fe(III) in hematite nanoparticles by Geobacter sulfurreducens.
abstract: The rates of microbial Fe(III) reduction of three sizes of hematite nanoparticles by Geobacter sulfurreducens were measured under two H2 partial pressures (0.01 and 1 atm) and three pH (7.0, 7.5, and 8.0) conditions. Hematite particles with mean primary particle sizes of 10, 30, and 50 nm were synthesized by a novel aerosol method that allows tight control of the particle size distribution. The mass-normalized reduction rates of the 10 and 30 nm particles were comparable to each other and higher than the rate for the 50 nm particles. However, the surface area-normalized rate was highest for the 30 nm particles. Consistent with a previously published model, the reduction rates are likely to be proportional to the bacteria-hematite contact area and not to the total hematite surface area. Surface area-normalized iron reduction rates were higher than those reported in previous studies, which may be due to the sequestration of Fe(II) through formation of vivianite. Similar initial reduction rates were observed under all pH and H2 conditions studied.
authors.affiliation: Department of Energy, Environmental, and Chemical Engineering, Center for Materials Innovation, Washington University in St. Louis, Missouri 63130, USA.
authors.forename: Beizhan
authors.initials: B
authors.lastname: Yan
authors.forename: Brian A
authors.initials: BA
authors.lastname: Wrenn
authors.forename: Soubir
authors.initials: S
authors.lastname: Basak
authors.forename: Pratim
authors.initials: P
authors.lastname: Biswas
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Giammar
mesh_terms: D005290:Ferric Compounds / Q000737:chemistry / Q000378:metabolism*; D045302:Geobacter / Q000378:metabolism* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles; D010084:Oxidation-Reduction
chemical_list: D005290:Ferric Compounds; C000499:ferric oxide