title: Biosynthesis of nanocrystal akaganéite from FeCl2 solution oxidized by Acidithiobacillus ferrooxidans cells.
abstract: Akaganéite (beta-FeOOH) is a major iron oxyhydroxide component in some soils, marine concretions, and acid mine drainage environments. Recently, synthetic beta-FeOOH has been found to be a promising absorbent in the treatment of metal-contaminated water. It has been recognized in previous study that akaganéite could be formed via FeCl2 chemical oxidation under specific conditions. Here we report a novel and simple method for akaganéite bioformation from FeCl2 solution oxidized by Acidithiobacillus ferrooxidans LX5 cells at 28 degrees C. After acclimation in modified 9K medium containing 0.2 M chloride, Acidithiobacillus ferrooxidans cells had great potential for oxidization of Fe2+ as FeCl2 solution, and then resulted in the formation of precipitates. The resulting precipitates were identified by powder X-ray diffraction and transmission FT-IR analyses to be akaganéite. Scanning electron microscopy images showed the akaganéite was spindle-shaped, approximately 200 nm long with an axial ratio of about 5, and the spindles had a rough surface. X-ray energy-dispersive spectral analyses indicated the chemical formula of the crystalloid akaganéite could be expressed as Fe8O8(OH)7.1(Cl)0.9 with Fe/Cl molar ratio of 8.93. The biogenetic akaganéite had a specific surface area of about 100 m2 g(-1) determined by BET method.
authors.affiliation: College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, P.R. China.
authors.forename: Huixin
authors.initials: H
authors.lastname: Xiong
authors.forename: Yuehua
authors.initials: Y
authors.lastname: Liao
authors.forename: Lixiang
authors.initials: L
authors.lastname: Zhou
authors.forename: Yiqun
authors.initials: Y
authors.lastname: Xu
authors.forename: Shimei
authors.initials: S
authors.lastname: Wang
mesh_terms: D042763:Acidithiobacillus / Q000378:metabolism*; D005290:Ferric Compounds / Q000378:metabolism*; D005296:Ferrous Compounds / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000648:ultrastructure; D010084:Oxidation-Reduction; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D005290:Ferric Compounds; D005296:Ferrous Compounds; D012996:Solutions; C473845:akaganeite; C029451:ferrous chloride