Transformation of Two-Line Ferrihydrite to Goethite and Hematite as a Function of pH and Temperature

Das, Soumya; Hendry, M. Jim; Essilfie-Dughan, Joseph

doi:10.1021/es101903y

Cited by 336 publications

(275 citation statements)

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“…This could be what triggers limited desorption by ion exchange in this case, due to the difference in electric charge between the electrolyte and ferrihydrite PZC (Table S2). Ferrihydrite transformation to goethite should not affect the results of this study (~1% transformed after 500 h [64]). …”

Section: Arsenic Release From Ferrihydritementioning

confidence: 70%

Liberation of Adsorbed and Co-Precipitated Arsenic from Jarosite, Schwertmannite, Ferrihydrite, and Goethite in Seawater

2014

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Sea level rise is able to change the geochemical conditions in coastal systems. In these environments, transport of contaminants can be controlled by the stability and adsorption capacity of iron oxides. The behavior of adsorbed and co-precipitated arsenic in jarosite, schwertmannite, ferrihydrite, and goethite in sea water (common secondary minerals in coastal tailings) was investigated. The aim of the investigation was to establish As retention and transport under a marine flood scenario, which may occur due to climate change. Natural and synthetic minerals with co-precipitated and adsorbed As were contacted with seawater for 25 days. During this period As, Fe, Cl, SO 4 , and pH levels were constantly measured. The larger retention capability of samples with co-precipitated As, in relation with adsorbed As samples, reflects the different kinetics between diffusion, dissolution, and surface exchange processes. Ferrihydrite and schwertmannite showed good results in retaining arsenic, although schwertmannite holding capacity was enhanced due its buffering capacity, which prevented reductive dissolution throughout the experiment. Arsenic desorption from goethite could be understood in terms of ion exchange between oxides and electrolytes, due to the charge difference generated by a low point-of-zero-charge and the change in stability of surface complexes between synthesis conditions and natural media. OPEN ACCESSMinerals 2014, 4 604

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Section: Arsenic Release From Ferrihydritementioning

confidence: 70%

Liberation of Adsorbed and Co-Precipitated Arsenic from Jarosite, Schwertmannite, Ferrihydrite, and Goethite in Seawater

2014

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“…Iron oxide transforming process is related to pH, temperature, the presence of ferrous ions, and the type of anions, such as chloride sulphate and oxyanions. Iron(hydro)oxide system is also redox sensitive (Lin et al 2008;Das et al 2011).…”

Section: Resultsmentioning

confidence: 99%

Iron oxides as weathering indicator and the origin of Luvisols from the Vistula glaciation region in Poland

2015

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Purpose The aim of the research was to determine the effect of lithogenic and pedogenic processes on the formation of Luvisols from the area of Vistula glaciation on the base of profile distribution of iron oxides and total iron in relation to texture and physicochemical properties. The indices of weathering of the soil material in genetic horizons were calculated, and changes in the content and forms of iron oxides were evaluated. Materials and methods The predominant type of soil in the study area is Luvisols under agricultural use, formed from silt formations on loam. The analyses were made applying the following methods: grain size composition using the sieve method and hydrometer method, the interpretation of the results was performed according to the World Reference Base for Soil Resources classification, the pH of soils was measured with the potentiometric method, C-organic with the WalkleyBlack dichromate method, the content of the following iron forms was determined (total iron (Fe t ) after the mineralization of soils in the mixture of HF and HClO 4 acids), free iron oxides were extracted using dithionite-citrate-bicarbonate method, and amorphous iron oxides after the ammonium oxalate extraction (using the Philips 9100PU apparatus). The clay mineralogy was estimated by X-ray diffraction analysis. Results and discussion It was observed that total iron enrichment occurs in argic horizons accompanied by iron depletion in luvic horizons, while the profile distribution of iron is similar to the distribution of clay. The (Fe d /Fe t ) ratio indicates a low degree of weathering; the highest values were observed in argic (Bt) horizons, which confirms the effect of the process of pedogenesis on the value of that index. In the soils investigated, crystalline iron oxides generally dominate over the amorphous forms. The mineralogical composition of clay fraction separated from the upper part of soils was different as compared to the underlying material. Conclusions The results of the study showed that iron contents (together with the other indicators) and its forms can be used to distinguish soil layers of different origin. The depth distribution of Fe d , Fe o and Fe t within soil profiles indicates that the soil material may be of different lithogenic origin in the studied pedons.

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“…Although ferrihydrite is comparatively bioavailable and is found in a wide range of environments, it is metastable and often undergoes phase transitions to more crystalline ferric iron oxides (e.g., hematite and goethite). Studies have shown that accelerated transformation of ferrihydrite to hematite and/or goethite occurs under conditions of elevated temperature and salt concentration, typical of a kilometer-deep-subsurface environment (65,66). Therefore, these more crystalline ferric iron minerals may be more representative of the Fe(III) oxide minerals found in deep-subsurface environments and are likely to be available to sustain survival and growth of the DMRB.…”

Section: Discussionmentioning

confidence: 99%

Orenia metallireducens sp. nov. Strain Z6, a Novel Metal-Reducing Member of the Phylum Firmicutes from the Deep Subsurface

Dong

Sanford

Boyanov

et al. 2016

Appl Environ Microbiol

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A novel halophilic and metal-reducing bacterium, Orenia metallireducens strain Z6, was isolated from briny groundwater extracted from a 2.02 km-deep borehole in the Illinois Basin, IL. This organism shared 96% 16S rRNA gene similarity with Orenia marismortui but demonstrated physiological properties previously unknown for this genus. In addition to exhibiting a fermentative metabolism typical of the genus Orenia, strain Z6 reduces various metal oxides [Fe(III), Mn(IV), Co(III), and Cr(VI)], using H 2 as the electron donor. Strain Z6 actively reduced ferrihydrite over broad ranges of pH (6 to 9.6), salinity (0.4 to 3.5 M NaCl), and temperature (20 to 60°C). At pH 6.5, strain Z6 also reduced more crystalline iron oxides, such as lepidocrocite (␥- IMPORTANCEA novel iron-reducing species, Orenia metallireducens sp. nov., strain Z6, was isolated from groundwater collected from a geological formation located 2.02 km below land surface in the Illinois Basin, USA. Phylogenetic, physiologic, and genomic analyses of strain Z6 found it to have unique properties for iron reducers, including (i) active microbial iron-reducing capacity under broad ranges of temperatures (20 to 60°C), pHs (6 to 9.6), and salinities (0.4 to 3.5 M NaCl), (ii) lack of c-type cytochromes typically affiliated with iron reduction in Geobacter and Shewanella species, and (iii) being the only member of the Halanaerobiales capable of reducing crystalline goethite and hematite. This study expands the scope of phylogenetic affiliations, metabolic capacities, and catalytic mechanisms for iron-reducing microbes.T he reduction of ferric [Fe(III)-bearing] minerals by microorganisms is widespread in both terrestrial and marine environments (1, 2) and is potentially one of the earliest forms of metabolism (3, 4). Due to the abundance of ferric minerals in the Earth's crust and the ubiquity of dissimilatory metal-reducing bacteria (DMRB), Fe(III) reduction is of global environmental significance, particularly in the subsurface. A phylogenetic variety of organisms has been reported for the capacity to reduce iron in a dissimilatory manner (1, 5). Dissimilatory iron reduction can be classified into two major groups. Many of the iron-reducing organisms (e.g., fermentative iron reducers) use Fe(III) as a minor side reaction in their metabolism but do not appear to conserve energy to support growth from this electron transfer. In comparison, the respiratory iron reducers conserve energy to support growth from Fe(III) via an electron transfer chain (1,5). DMRB strongly influence the biogeochemical cycling of metals and mineralization of organic matter in aquatic and sedimentary environments (1,(6)(7)(8). In addition, DMRB play a key role in the bioremediation of hazardous contaminants, such as heavy metals, radionuclides, and hydrocarbons (9). DMRB capable of reducing ferric minerals have previously been isolated from gold mines, petroleum reservoirs, and other

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Transformation of Two-Line Ferrihydrite to Goethite and Hematite as a Function of pH and Temperature

Cited by 336 publications

References 45 publications

Liberation of Adsorbed and Co-Precipitated Arsenic from Jarosite, Schwertmannite, Ferrihydrite, and Goethite in Seawater

Liberation of Adsorbed and Co-Precipitated Arsenic from Jarosite, Schwertmannite, Ferrihydrite, and Goethite in Seawater

Iron oxides as weathering indicator and the origin of Luvisols from the Vistula glaciation region in Poland

Orenia metallireducens sp. nov. Strain Z6, a Novel Metal-Reducing Member of the Phylum Firmicutes from the Deep Subsurface

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