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In this study, we evaluated the feasibility of using ferric salts including FeCl 3 and Fe(NO 3 ) 3 as extracting and oxidizing agents for a soil washing process to remediate Pb-contaminated soils. We treated various Pb minerals including PbO, PbCO 3 , Pb 3 (CO 3 ) 2 (OH) 2 , PbSO 4 , PbS, and Pb 5 (PO 4 ) 3 (OH) using ferric salts, and compared our results with those obtained using common washing agents of HCl, HNO 3 , disodium-ethylenediaminetetra-acetic acid (Na 2 -EDTA), and citric acid. The use of 50 mM Fe(NO 3 ) 3 extracted significantly more Pb (above 96% extraction) from Pb minerals except PbSO 4 (below 55% extraction) compared to the other washing agents. In contrast, washing processes using FeCl 3 and HCl were not effective for extraction from Pb minerals because of PbCl 2 precipitation. Yet, the newly formed PbCl 2 could be dissolved by subsequent wash with distilled water under acidic conditions. When applying our washing method to remediate field-contaminated soil from a shooting range that had high concentrations of Pb 3 (CO 3 ) 2 (OH) 2 and PbCO 3 , we extracted more Pb (approximately 99% extraction) from the soil using 100 mM Fe(NO 3 ) 3 than other washing agents at the same process conditions. Our results show that ferric salts can be alternative washing agents for Pb-contaminated soils in view of their extracting and oxidizing abilities. [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus is a halophilic bacterium endemic to coastal areas, and its pathogenicity has caused widespread seafood poisoning. In our previous research, the protein expression of V. parahaemolyticus in Fe medium was determined using isobaric tags for relative and absolute quantitation (iTRAQ). Here, nuclear magnetic resonance (NMR) was used to detect changes in the V. parahaemolyticus metabolome. NMR spectra were obtained using methanol-water extracts of intracellular metabolites from V. parahaemolyticus under various culture conditions, and 62 metabolites were identified, including serine, arginine, alanine, ornithine, tryptophan, glutamine, malate, NAD, NADP, oxypurinol, xanthosine, dCTP, uracil, thymine, hypoxanthine, and betaine. Among these, 21 metabolites were up-regulated after the stimulation of the cells by ferric iron, and 9 metabolites were down-regulated. These metabolites are involved in amino acid and protein synthesis, energy metabolism, DNA and RNA synthesis and osmolality. Based on these results, we conclude that Fe influences the metabolite profiles of V. parahaemolyticus. [ABSTRACT FROM AUTHOR]

Iron- and aluminum-bearing MgSiO3 bridgmanite is the most abundant mineral in the Earth's interior; hence its crystal chemistry is fundamental to expanding our knowledge of the deep Earth and its evolution. In this study, the valence and spin state of iron in well-characterized Al-free Fe3+-rich bridgmanite were investigated by means of Mössbauer spectroscopy to understand the effect of ferric iron on the spin state. We found that a minor amount of Fe3+ is in the low-spin state above 36 GPa and that its proportion does not increase substantially with pressure up to 83 GPa. This observation is consistent with recent experimental studies that used Mössbauer and X-ray emission spectroscopy. In the Earth's deep lower mantle, Fe3+ spin crossover may take place at depths below 900 and 1200 km in pyrolite and MORB, respectively. However, the effect of spin crossover on physical properties may be small due to the limited amount of Fe3+ in the low-spin state. [ABSTRACT FROM AUTHOR]

Given that secondary magnetite is common in serpentinites, it is clear that serpentinites are oxidized rocks. Questions remain, however, concerning the distribution of ferric iron among magnetite and serpentine minerals and the role of ferric iron-rich serpentine in the formation of secondary magnetite. Direct determination of ferric iron in serpentine is not possible using an electron microprobe. We show, however, that the stoichiometic effects of ferric iron substitutions are detectable, although not quantifiable, by microprobe. First, we demonstrate that for studies that provide both microprobe analyses of major elements of serpentine and Mössbauer analysis of ferric iron, substitution effects are obvious. Next, it is equally clear that the early veins forming at the onset of olivine hydration (type 1 veins) show no indication of the presence of ferric serpentine, although a small amount of ferric ‘brucite’ may occur. Finally, we show that secondary (type 2) veins, which form as the system becomes open to fluids in equilibrium with plagioclase or pyroxene, contain, in addition to significant alumina, stoichiometric indications of ferric iron substitution. The serpentine in these veins is magnesian, usually with Mg#s around 96–98. Thus, even if a significant proportion of this iron is ferric, it comprises only a small fraction of the total ferric iron budget of the rock. Given that reduced iron is known to be abundant in early-formed brucite and early-formed serpentine and given that brucite, in particular, is absent from evolved serpentine veins, we propose that most magnetite in serpentinites forms as a tertiary product via oxidation of brucite. [ABSTRACT FROM PUBLISHER]

We report a highly selective method for identification and detection of iron (III) (ferric iron, Fe 3+ ) using Nile red (NR) as a complexing agent. Fe 3+ preferentially binds with NR in dimethylformamide (DMF)/water (1:1) solution over other cations such as Fe 2+ , Cu 2+ , Pb 2+ , Hg 2+ , Mn 2+ , Ni 2+ , Zn 2+ , Co 2+ and Cd 2+ at room temperature. In the presence of Fe 3+ , the color of NR solution changes from purple to dark brown, which is detectable with bare eyes. Using UV–vis spectroscopy, we could measure the amount of Fe 3+ in the sample solution by monitoring changes in absorption from 540 to 580 nm; the linear range and the limit of detection are 30–1000 µM and 24.9 µM, respectively. Taking advantage of the NR selectivity, we treated partially oxidized graphene sheets (po-Gr) with NR to obtain po-Gr-NR dispersion by ultrasonication. The NR-treated po-Gr flakes (po-Gr-NR) were characterized by UV–vis, FT-IR, and Raman spectroscopies and FE-SEM, which indicated attachment of NR on po-Gr sheets. The po-Gr-NR hybrid film deposited glassy carbon electrode (po-Gr-NR/GCE) served as the Fe 3+ sensor. Differential pulse voltammetry was used to investigate the detection of Fe 3+ in 0.05 M HCl+0.05 M KCl solution. The linear range and the limit of detection of Fe 3+ were from 37.5 nM to 21.53 µM and 18.7 nM, respectively. Furthermore, this sensor was successfully used to measure Fe 3+ content in red wine samples. [ABSTRACT FROM AUTHOR]

Background: Randomized trials have demonstrated that a phosphate binder ferric citrate (FeC) increases iron parameters in comparison with other phosphate binders, but the doses for FeC to improve iron stores safely have not been clarified. Methods: We examined changes of iron parameters and blood hemoglobin (Hb) in 7 iron-deficient hemodialysis (HD) patients taking FeC 750 mg/day as a phosphate binder. Results: The median serum transferrin saturation and ferritin increased from 13% (interquartile range (IQR) 7-18) to 28% (IQR 22-31; p = 0.010) and from 17 ng/ml (IQR 11-60) to 106 ng/ml (IQR 58-176; p = 0.015) by 2 and 3 months respectively. With the persistence of these levels thereafter, the FeC administration reduced the usage of erythropoiesis-stimulating agents while maintaining adequate blood Hb levels. Conclusion: Oral FeC 750 mg/day improves iron stores without inducing iron overload in hyperphosphatemic HD patients. [ABSTRACT FROM AUTHOR]

Glyphosate, the most used herbicide in the world, has a residue problem that cannot be ignored. However, glyphosate itself does not have fluorescence emission and lacks the conditions for fluorescence detection. In this work, a rapid and selective fluorescence detection method of glyphosate was designed by an 'on-off-on' fluorescent switch based on a luminous covalent organic framework (L-COF). Only the fixed concentration of Fe 3+ as an intermediate could trigger the fluorescent switch and no incubation step was required. The proposed method showed good accuracy with a correlation coefficient of 0.9978. The method's limits of detection and quantitation were 0.88 and 2.93 μmol/L, which were lower than the maximum allowable residue limits in some regulations. Environmental water samples and tomatoes were selected as actual samples to verify the application in a complex matrix. A satisfactory mean recovery from 87% to 106% was gained. Furthermore, Fe 3+ could induce fluorescence quenching of L-COF through the photo-induced electron transfer (PET) effect, while the addition of glyphosate could block the PET effect to achieve detection. These results demonstrated the proposed method had abilities to detect glyphosate and broaden the application of L-COF., (© 2023 John Wiley & Sons, Ltd.)

The pathogenic bacterium Aeromonas hydrophila has been shown to exclusively utilize a ligand exchange mechanism for siderophore-mediated iron uptake, with a single nonspecific siderophore receptor facilitating iron exchange. However, the genes involved in this process, including the gene encoding the nonspecific receptor, are unknown. Here we identify and characterize a novel gene, nsr1, from A. hydrophila that encodes a putative protein with high homology and significant predicted structural similarities to the FhuA protein and other known ferric-siderophore receptors. This protein appears to localize on the cell membrane and is likely to be the receptor involved in the ligand exchange siderophore-mediated iron uptake mechanism of A. hydrophila. It is expected that this information may lead to the development of new antibiotics targeting either nsr1 or its gene product for use in controlling A. hydrophila infection.

[Display omitted] • Fe(Ш) (10–50 mg/L) inhibited NO 3 – removal and caused NO 2 – accumulation of SPD. • Continuous Fe(Ш) addition changed the microbial community structure. • Fe(Ш) had obvious inhibition to aerobic denitrifying genes (e.g. napA/B). • Fe(Ш) inhibited the genes related to electron carrier generation in C metabolism. The effect of ferric iron (Fe(Ш)) on the performance of heterotrophic solid-phase denitrification (SPD) using biodegradable polymer composite as the electron donor was investigated. The results of continuous batch experiments showed that the addition of over 10 mg/L Fe(Ш) significantly inhibited nitrate removal and led to the accumulation of nitrite. The addition of Fe(Ш) reduced the microbial community diversity and shifted the community dominated by complete denitrifiers (e.g. Thauera) to that dominated by incomplete denitrifiers (e.g. Thermomonas , Stenotrophomonas and Sphingomonas). The predicted analysis of microbial function by PICRUSt2 indicated that the relative abundance of denitrifying genes, including napA/B , nirS and nosZ , were remarkably reduced in the Fe(Ш) groups comparing with the control group. In addition, Fe(Ш) inhibited the genes related to the generation of electron carriers, NADH and FADH 2 , in TCA cycle and glycolysis processes, which could result in a lower carbon utilization efficiency for microbial denitrification. [ABSTRACT FROM AUTHOR]

We describe a new methodology to collect energy domain Mössbauer spectra of inclusions in natural diamonds using a Synchrotron Mössbauer Source (SMS). Measurements were carried out at the Nuclear Resonance beamline ID18 at the European Synchrotron Radiation Facility (Grenoble, France). We applied this non-destructive approach to collect SMS spectra of a ferropericlase inclusion still contained within its diamond host from Juina (Brazil). The high spatial resolution of the measurement (~ 15 μm) enabled multiple regions of the 190 × 105 μm 2 inclusion to be sampled and showed that while Fe 3 + /Fe tot values in ferropericlase were below the detection limit (0.02) overall, there was a magnetic component whose abundance varied systematically across the inclusion. Hyperfine parameters of the magnetic component are consistent with magnesioferrite, and the absence of superparamagnetism allows the minimum particle size to be estimated as ~ 30 nm. Bulk Fe 3 + /Fe tot values are similar to those reported for other ferropericlase inclusions from Juina, and their variation across the inclusion can provide constraints on its history. [ABSTRACT FROM AUTHOR]

Hydrocarbon seepages bring oil and gas from petroleum reservoirs to the surface, these hydrocarbons can generate various kinds of rock alterations, including bleaching of red beds and mineralogical changes. Satellite and airborne remote sensing techniques have been utilized in the detection of rock alterations and hydrocarbon seepages; however, they have limited resolutions and are unable to map vertical outcrops. Ground-based remote sensing techniques hold great potential to characterize rocks with great precisions and resolutions. This study used ground-based Specim hyperspectral data to detect hydrocarbon-induced rock alterations of the Rush Springs sandstone at the Cement field in southeast Anadarko basin, Oklahoma. Hyperspectral data of outcrops and hand specimens were examined, and spectral angle mapper technique was used to compare spectral similarity between image pixels and reference spectra. Laboratory spectroscopy was used to assist with mineral identification and image classification. Remote sensing data detected bleaching of red beds and carbonate cementation. Combining lithological, spectroscopic, remote sensing and geochemical data, this study built a model for petroleum seepage and related rock alterations, and provided a workflow for employing remote sensing techniques in resource exploration. [ABSTRACT FROM AUTHOR]

We report herein the use of ferric iron (Fe 3+ ) and sulfite (SO 3 2− ) to activate persulfate (S 2 O 8 2− ). Decolorization and mineralization of reactive Brilliant Red X-3B (a model azo dye) by an Fe(III)/sulfite/persulfate triple system have been investigated in aqueous solutions. Initial pH and dissolved oxygen are important factors influencing X-3B decolorization in this system. The rapid decolorization process occurred in 30 min and about 85% of X-3B was decolorized in this triple system at initial pH 6.0. Moreover, about 66.4% of the TOC was removed through reaction for 36 h. The generation of SO 4 •− and HO • were identified through radical quenching experiments and by electron spin resonance (ESR), which contributed to 61.1% and 28.9% of the oxidation process. Degradation products of X-3B were identified by LC-ESI-MS, and the degradation pathway was proposed. Furthermore, other organic pollutants, such as Orange II, metoprolol, imipramine, naproxen, estradiol, and amitriptyline, could also be efficiently degraded in this triple system. The results of the present work suggest that the Fe(III)/sulfite/persulfate triple system can be used for the rapid decolorization and partial mineralization of dyeing wastewater at near-neutral pH values. [ABSTRACT FROM AUTHOR]

The short- and long-term influences of ferric iron (Fe(III)) on nutrients removal and nitrous oxide (NO) emission during SNDPR process were evaluated. According to the continuous cycle experiments, it was concluded that the addition of Fe(III) could lower the nitrogen removal of the following cycle during SNDPR process, which was mainly induced by the chemical removal of phosphorus. However, the impacts were transitory, and simultaneous nitrogen and phosphorus removal would recover from the inhibition of Fe(III) after running certain cycles. Moreover, the addition of Fe(III) could stimulate NO emission transitorily during SNDPR process. However, if Fe(III) was added into reactor continuously, the nitrogen removal would be improved, especially at low Fe load condition. It was because that the activity of NO reductase was enhanced by the addition of Fe. However, the low Fe load in reactor would induce more NO emission. When Fe(III) load was 40 mg/L in the reactor, the NO yield was 10 % higher than control. The TN removal was weakened when Fe(III) load reached to 60 mg/L, and the NO yield was lower than control, due to the inhibition of the high Fe load on denitrification enzymes. [ABSTRACT FROM AUTHOR]

A highly selective method has been proposed for the determination of iron cation (Fe 3+ ). (Nitriloacetic acid-nickel)-layered double hydroxide ((NTA-Ni)-LDH) was successfully synthesized and used as dissolvable sorbent in dispersive solid-phase extraction to pre-concentrate and separate Fe 3+ from aqueous phase. Since Fe 3+ has a larger formation constant with NTA compared to Ni 2+ , subsequently ion exchange occurred when (NTA-Ni)-LDH was added to the sample solution. The resultant (NTA-Fe)-LDH sol was isolated and transferred in an acidic medium containing potassium thiocyanate (KSCN). Since (NTA-Fe)-LDH could be dissolved in acidic conditions, Fe 3+ was released and reacted with SCN − to form an Fe-SCN complex. The resulting product was measured by ultraviolet-visible spectrometry for quantitative detection of Fe 3+ . Extraction factors, including sample pH, reaction pH, extraction temperature, extraction time, reaction time and concentration of KSCN were optimized. This method achieved a low limit of detection of 15.2 nM and a good linear range from 0.05 to 50 μM (r 2 =0.9937). A nearly 18-fold enhancement of signal intensity was achieved after selective extraction. The optimized conditions were validated by applying the method to determine Fe 3+ in seawater samples. [ABSTRACT FROM AUTHOR]

This study systematically evaluated the effect of ferric iron on sulfate reduction to sulfide, feed digestion and fermentation, methane production, and populations of select ruminal microbes using in vitro rumen cultures. Ferric oxide (Fe 2 O 3 ) and ferric citrate (C 6 H 5 FeO 7 ) at six concentrations (0, 25, 50, 100, 150, and 200 mg/L as Fe 3+ ) were tested. Ferric iron decreased production of both H 2 S gas in culture headspace (up to 71.9%) and aqueous sulfide (up to 80.8%), without adversely affecting other fermentation parameters, with ferric citrate being more effective than ferric oxide. Total archaeal population was increased by ferric citrate, but methane production was not affected significantly. The population of sulfate reducing bacteria was affected differently by ferric oxide than by ferric citrate. The results of this study could guide future in vivo studies to develop effective solutions to abate sulfur-associated polioencephalomalacia in cattle fed high-sulfur diet such as dried distiller’s grains with solubles. [ABSTRACT FROM AUTHOR]

Numerous techniques are available to determine the amount of Fe2+ and Fe3+ in minerals. Calculating Fe2+ and Fe3+ by charge-balance using electron probe microanalysis (EPMA) data is the most common method, but several studies question the usefulness and accuracy of this approach (Canil and O'Neill 1996; Dyar et al. 1993, 2012; Lalonde et al. 1998; Li et al. 2005; McGuire et al. 1989; Schingaro et al. 2016; Schmid et al. 2003; Sobolev et al. 2011). We compile and compare data for natural garnets that have been analyzed by both EPMA and Mössbauer spectroscopy. Comparison of Fe3+/ΣFe determined by charge-balance vs. Mössbauer spectroscopy shows an approximate 1:1 correlation. The EPMA data set of Dyar et al. (2012) is reexamined and it is shown that disagreement between EPMA and Mössbauer for their data is not nearly as bad as reported. Data for charge-balance vs. Mössbauer spectroscopy are compared and show that the EPMA/charge-balance approach provides a suitable alternative when other methods are not practical. [ABSTRACT FROM AUTHOR]

Using large volume press, samples of bridgmanites (Bg) in equilibrium with both silicate melt and liquid Fe-alloy were synthesized to replicate the early period of core-mantle segregation and magma ocean crystallization. We observe that the Fe partition coefficient between Bg and silicate melt (DFeBg/melt) varies strongly with the degree of partial melting (F). It is close to 1 at very low F and adopts a constant value of ~0.3 for F values above 10 wt%. In the context of a partially molten mantle, a larger F (closer to liquidus) should yield Fe-depleted Bg grains floating in the liquid mantle. In contrast, a low F (closer to solidus) should yield buoyant pockets of silicate melt in the dominantly solid mantle. We also determined the valence state of Fe in these Bg phases using X-ray absorption near-edge spectroscopy (XANES). Combining our results with all available data sets, we show a redox state of Fe in Bg more complex than generally accepted. Under the reducing oxygen fugacities (fO2) of this study ranging from IW-1.5 and IW-2, the measured Fe3+ content of Bg is found moderate (Fe3+/ΣFe = 21 ± 4%) and weakly correlated with Al content. When fO2 is comprised between IW-1 and IW, this ratio is correlated with both Al content and oxygen fugacity. When fO2 remains between IW and Re/ReO2 buffers, Fe3+/ΣFe ratio becomes independent of fO2 and exclusively correlated with Al content. Due to the incompatibility of Fe in Bg and the variability of its partition coefficient with the degree of melting, fractional crystallization of the magma ocean can lead to important chemical heterogeneities that will be attenuated ultimately with mantle stirring. In addition, the relatively low-Fe3+ contents found in Bg (21%) at the reducing conditions (IW-2) prevailing during core segregation seem contradictory with the 50% previously suggested for the actual Earth's lower mantle. This suggests the presence of 1.7 wt% Fe3+ in the lower mantle, which reduces the difference with the value observed in the upper mantle (0.3 wt%). Reaching higher concentrations of trivalent Fe requires additional oxidation processes such as the late arrival of relatively oxidized material during the Earth accretion or interaction with oxidized subducting slabs. [ABSTRACT FROM AUTHOR]