title: Sorption of ferrous and ferric iron by extracellular polymeric substances (EPS) from acidophilic bacteria.
abstract: The sorption of Fe(II) and Fe(III) by extracellular polymeric substances (EPS) of acidophilic bacteria Acidiphilium 3.2Sup(5) and Acidithiobacillus ferrooxidans, harvested from the ecosystem of the Tinto River (Huelva, Spain), was investigated. EPS from mixed cultures of both bacteria (EPS(mixed)) and pure cultures of A. 3.2Sup(5) (EPS(pure)) were extracted with ethylenediamine tetraacetic acid (EDTA) and were characterized by Fourier-transform infrared (FTIR), electron photoemission (XPS), x-ray diffraction (DRX), and energy dispersive x-ray (EDX) spectroscopy and scanning electron microscopy (SEM). EPS pure were loaded, in sorption tests, with Fe(II) and Fe(III). The results obtained indicate that the biochemical composition and structure of EPS(mixed) was very similar to that of EPS(pure). Besides, results indicate that EPS(mixed) adsorbed Fe(II) and Fe(III) by preferential interaction with the carboxyl group, which favored the formation of Fe(II)/Fe(III) oxalates. These species were also formed in EPS(pure) loaded with Fe(II)/Fe(III). All this behavior suggested that the sorption of iron by EPS(mixed) was similar to sorption of EPS(pure), which fitted the Freundlich model. Thus, the iron uptake of EPS(mixed) reached 516.7 ± 23.4 mg Fe/g-EPS at an initial concentration of 2.0 g/L of Fe(total) and Fe(II)/Fe(III) ratio of 1.0.
authors.affiliation: Faculty of Engineering and Architecture, Section of Aqueous Process in Metallurgy, University Arturo Prat, Iquique, Chile. jaime.tapia@unap.cl
authors.forename: Jaime M
authors.initials: JM
authors.lastname: Tapia
authors.forename: Jesús
authors.initials: J
authors.lastname: Muñoz
authors.forename: Felisa
authors.initials: F
authors.lastname: González
authors.forename: Maria L
authors.initials: ML
authors.lastname: Blázquez
authors.forename: Antonio
authors.initials: A
authors.lastname: Ballester
mesh_terms: D041801:Acidiphilium / Q000737:chemistry / Q000648:ultrastructure; D042763:Acidithiobacillus / Q000737:chemistry / Q000648:ultrastructure; D000327:Adsorption; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification; D005290:Ferric Compounds / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D011135:Polysaccharides, Bacterial / Q000737:chemistry* / Q000302:isolation & purification; D045483:Rivers / Q000382:microbiology; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D001426:Bacterial Proteins; D005290:Ferric Compounds; D005296:Ferrous Compounds; D011135:Polysaccharides, Bacterial; C020748:ferrous sulfate; C024823:ferric sulfate