FE-SEM Study of Microbially Formed Jarosites by <I>Acidithiobacillus ferrooxidans</I>

Abstract

Morphological characterization of jarosite groups formed from Fe(III) biologically oxidized with different numbers of Acidithiobacillus ferrooxidans was conducted using FE-SEM. The higher population of A. ferrooxidans resulted in more distinct jarosite mineral shape, and stronger Raman intensities for potassium jarosite, ammoniojarosite and argentojarosite. The morphology of the jarosites might be dependent on iron-oxidizing activity of A. ferrooxidans.The technique was applied to identify jarosite compounds formed during microbially mediated dissolution of arsenopyrite by A. ferrooxidans. It is difficult to identify this jarosite compound by X-ray diffraction and Raman spectroscopy because amounts are typically low and the crystallization is poor in minerals formed by microbially mediated oxidation. However, FE-SEM image provided helpful information for identification of jarosite compounds.The results suggest that morphology would provide useful information for identification and history of jarosite minerals as geochemical samples.

Biogeochemical Cycling of Silver in Acidic, Weathering Environments

“…The occurrence of argentojarosite (AgFe 3 (SO 4 ) 2 (OH) 6 ) is rare relative to other jarosite-group endmembers; however, it accounts for a substantial fraction of Ag within gossan and is thought to reflect the early phases of gossanization [23,24]. Under acidic weathering conditions, such as those occurring within and around open pit mine sites, dissolved Fe 3+ , H + and SO 4 2− can form jarosite-group minerals that could act as a "sink" for Ag + [25][26][27][28][29][30]. …”

Biosynthesis of natrojarosite by immobilized iron-oxidizing bacteria

“…4 shows a FTIR spectrum with different vibration modes. It indicated that: the absorption peak at 3353 cm −1 was ascribed to the O\H stretching; the ν4, ν3, ν2 and ν1 vibrations of sulfate were represented in the wavenumbers of 626 cm and 1006 cm −1 , respectively (Henao and Godoy, 2010); the vibration peaks of FeO 6 octahedron were observed in the wavenumbers of 511 cm −1 and 473 cm −1 (Sasaki et al, 2006). Consequently, the above results prove the precipitates bio-mediated to be jarosites.…”

“…It is crucial to minimize jarosite formation in order to increase efficiency (Chung et al, 2005;Wang et al, 2007). So the formation of jarosite during the oxidation of ferrous iron by A. ferrooxidans was studied (Sasaki et al, 2006;Liao et al, 2009;Daoud and Karamanev, 2006). On the other side jarosite is an excellent mineral pigment in mural paintings, tiles and ceramic products.…”

Terraced Iron Formations: Biogeochemical Processes Contributing to Microbial Biomineralization and Microfossil Preservation

“…Acidophilic, iron-oxidizing bacteria produce increased H + concentrations as well as schwertmannite and hydronium jarosite ((H 3 O)Fe 3 (SO 4 ) 2 (OH) 6 ) as by-products of their active metabolism. These IOM precipitates occur as pseudoacicular and euhedral crystal morphologies, respectively [11,17,18,29,30]. The average pH of the bacterial enrichments was determined, and IOM precipitates were collected, air dried for 24 h, and weighed to obtain an average mass.…”

“…From a biogeochemical perspective, acidophilic, iron-oxidizing bacteria, e.g., Acidithiobacillus ferrooxidans and Leptospirillum ferriphilum, are known to colonize and accelerate the dissolution of metal sulfides. In doing so, they form secondary iron oxyhydroxide mineral (IOM) precipitates, such as schwertmannite, which comprises TIFs [1][2][3][4][5][6][7][8][9][10][11][12]. In addition to chemolithotrophic bacteria, iron oxidation has also been attributed to phototrophic microbes, such as cyanobacteria and algae, which produce oxygen as by-products [2].…”