Neutrophilic iron-oxidizing bacteria: occurrence and relevance in biological drinking water treatment

DEFF Research Database (Denmark)

Gülay, Arda; Musovic, Sanin; Albrechtsen, Hans-Jørgen

2013-01-01

Rapid sand filtration (RSF) is an economical way to treat anoxic groundwater around the world. It consists of groundwater aeration followed by passage through a sand filter. The oxidation and removal of ferrous iron, which is commonly found in anoxic groundwaters, is often believed to be a fully...... role of FeOB in iron removal at waterworks using RSF technologies....... physicochemical process. However, persistently low temperatures in RSF across Denmark may negatively affect the kinetics of chemical oxidation. The slower chemical oxidation of ferrous iron may increase the chances for iron bioconversion by neutrophilic iron-oxidizing bacteria (FeOB), which are found naturally...

Potential for microbial oxidation of ferrous iron in basaltic glass.

Science.gov (United States)

Xiong, Mai Yia; Shelobolina, Evgenya S; Roden, Eric E

2015-05-01

Basaltic glass (BG) is an amorphous ferrous iron [Fe(II)]-containing material present in basaltic rocks, which are abundant on rocky planets such as Earth and Mars. Previous research has suggested that Fe(II) in BG can serve as an energy source for chemolithotrophic microbial metabolism, which has important ramifications for potential past and present microbial life on Mars. However, to date there has been no direct demonstration of microbially catalyzed oxidation of Fe(II) in BG. In this study, three different culture systems were used to investigate the potential for microbial oxidation of Fe(II) in BG, including (1) the chemolithoautotrophic Fe(II)-oxidizing, nitrate-reducing "Straub culture"; (2) the mixotrophic Fe(II)-oxidizing, nitrate-reducing organism Desulfitobacterium frappieri strain G2; and (3) indigenous microorganisms from a streambed Fe seep in Wisconsin. The BG employed consisted of clay and silt-sized particles of freshly quenched lava from the TEB flow in Kilauea, Hawaii. Soluble Fe(II) or chemically reduced NAu-2 smectite (RS) were employed as positive controls to verify Fe(II) oxidation activity in the culture systems. All three systems demonstrated oxidation of soluble Fe(II) and/or structural Fe(II) in RS, whereas no oxidation of Fe(II) in BG material was observed. The inability of the Straub culture to oxidize Fe(II) in BG was particularly surprising, as this culture can oxidize other insoluble Fe(II)-bearing minerals such as biotite, magnetite, and siderite. Although the reason for the resistance of the BG toward enzymatic oxidation remains unknown, it seems possible that the absence of distinct crystal faces or edge sites in the amorphous glass renders the material resistant to such attack. These findings have implications with regard to the idea that Fe(II)-Si-rich phases in basalt rocks could provide a basis for chemolithotrophic microbial life on Mars, specifically in neutral-pH environments where acid-promoted mineral dissolution and

Preparation, physical characterization, and stability of Ferrous-Chitosan microcapsules using different iron sources

Science.gov (United States)

Handayani, Noer Abyor; Luthfansyah, M.; Krisanti, Elsa; Kartohardjono, Sutrasno; Mulia, Kamarza

2017-11-01

Dietary modification, supplementation and food fortification are common strategies to alleviate iron deficiencies. Fortification of food is an effective long-term approach to improve iron status of populations. Fortification by adding iron directly to food will cause sensory problems and decrease its bioavailability. The purpose of iron encapsulation is: (1) to improve iron bioavailability, by preventing oxidation and contact with inhibitors and competitors; and (2) to disguise the rancid aroma and flavor of iron. A microcapsule formulation of two suitable iron compounds (iron II fumarate and iron II gluconate) using chitosan as a biodegradable polymer will be very important. Freeze dryer was also used for completing the iron microencapsulation process. The main objective of the present study was to prepare and characterize the iron-chitosan microcapsules. Physical characterization, i.e. encapsulation efficiency, iron loading capacity, and SEM, were also discussed in this paper. The stability of microencapsulated iron under simulated gastrointestinal conditions was also investigated, as well. Both iron sources were highly encapsulated, ranging from 71.5% to 98.5%. Furthermore, the highest ferrous fumarate and ferrous gluconate loaded were 1.9% and 4.8%, respectively. About 1.04% to 9.17% and 45.17% to 75.19% of Fe II and total Fe, were released in simulated gastric fluid for two hours and in simulated intestinal fluid for six hours, respectively.

Neutrophilic Iron Oxidizing Bacteria: Occurrence and Relevance in Biological Drinking Water Treatment

DEFF Research Database (Denmark)

Gülay, Arda; Musovic, Sanin; Albrechtsen, Hans-Jørgen

Rapid sand filtration (RSF) is an economical way to treat anoxic groundwater around the world. It consists of groundwater aeration followed by passage through a sand filter. The oxidation and removal of ferrous iron, which is commonly found in anoxic groundwaters, is often believed to be a fully......, neutrophilic iron oxidizers were present at the level of up to 7 105 cells per gram sediment. The spatial abundance and diversity of FeOB inferred by DGGE fingerprinting differed greatly both between and within individual sand filters. The results suggest a larger than assumed role of FeOB in iron removal...... physicochemical process. However, persistently low temperatures in RSF across Denmark may negatively affect the kinetics of chemical oxidation. The slower chemical oxidation of ferrous iron may increase the chances for iron bioconversion by neutrophilic iron-oxidizing bacteria (FeOB), which are found naturally...

Evaluation of iron transport from ferrous glycinate liposomes using ...

African Journals Online (AJOL)

Background: Iron fortification of foods is currently a strategy employed to fight iron deficiency in countries. Liposomes were assumed to be a potential carrier of iron supplements. Objective: The objective of this study was to investigate the iron transport from ferrous glycinate liposomes, and to estimate the effects of liposomal ...

Arsenite and ferrous iron oxidation linked to chemolithotrophic denitrification for the immobilization of arsenic in anoxic environments

Science.gov (United States)

Sun, W.; Sierra-Alvarez, R.; Milner, L.; Oremland, R.; Field, J.A.

2009-01-01

The objective of this study was to explore a bioremediation strategy based on injecting NO3- to support the anoxic oxidation of ferrous iron (Fe(II)) and arsenite (As(III)) in the subsurface as a means to immobilize As in the form of arsenate (As(V)) adsorbed onto biogenic ferric (Fe(III)) (hydr)oxides. Continuous flows and filled columns were used to simulate a natural anaerobic groundwater and sediment system with co-occurring As(III) and Fe(II) in the presence (column SF1) or absence (column SF2) of nitrate, respectively. During operation for 250 days, the average influent arsenic concentration of 567 ??g L-1 was reduced to 10.6 (??9.6) ??g L-1 in the effluent of column SF1. The cumulative removal of Fe(II) and As(III) in SF1 was 6.5 to 10-fold higher than that in SF2. Extraction and measurement of the mass of iron and arsenic immobilized on the sand packing of the columns were close to the iron and arsenic removed from the aqueous phase during column operation. The dominant speciation of the immobilized iron and arsenic was Fe(III) and As(V) in SF1, compared with Fe(II) and As(III) in SF2. The speciation was confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results indicate that microbial oxidation of As(III) and Fe(II) linked to denitrification resulted in the enhanced immobilization of aqueous arsenic in anaerobic environments by forming Fe(III) (hydr)oxide coated sands with adsorbed As(V). ?? 2009 American Chemical Society.

Oral iron therapy in human subjects, comparative absorption between ferrous salts and iron polymaltose

International Nuclear Information System (INIS)

Jacobs, P.; Johnson, G.; Wood, L.

1984-01-01

Iron absorption was directly compared between equivalent doses of ferrous salts and a polymaltose complex using a twin-isotope technique in which each individual acts as his own control. In the first study, bioavailability of iron from ferrous sulfate and the complex was defined at physiologic doses of 5 mg (Group 1: n = 14) and therapeutic doses of 50 mg (Group 2: n = 13). In Group 1, mean absorption from salt was 47.77% (SD 14.58%) and from polymaltose, 46.56% SD 17.07%). In Group 2, mean absorption from salt was 32.92% (SD 13.42%) and from polymaltose, 27.07% (SD 6.50%). In a second study, 100 mg of iron in a chewable formulation was used to compare absorption between equal doses of ferrous fumarate and the polymaltose complex. Mean absorption from salt was 10.25% (SD 6.89%) and from polymaltose 10.68% (SD 4.68%). At all three dosage levels, iron is equally available from salt or polymaltose for hemoglobin synthesis (p greater than 0.20), and absorption negatively correlated with plasma ferritin (p less than 0.01). These two materials may be used interchangeably in the treatment of patients with absolute iron deficiency

Production of ferrous sulfate from residue from the iron mining

International Nuclear Information System (INIS)

Cardoso, K.A; Riella, H.G.; Abreu, E.F.; Carvalho, E.F. Urano de; Durazzo, M.

2012-01-01

This paper was developed from a residue obtained by processing iron ore exploited by the mining company Samarco S/A. The residue was characterized and the analyses showed that it contains about 70% of the mineral hematite (Fe 2 O 3 ) and also that some economically important products could be produced. One is the ferrous sulfate that can be used in pharmaceuticals and also that can be used in the treatment of iron deficiency anemia. The iron, in addition to is importance for the industrial production of steel and parts in general, also has great biological importance in all living beings. In order to produce ferrous sulfate from the byproduct in question, it was developed a obtaining route using metallic iron as hematite reductor and sulfuric acid to form the salt. (author)

Iron-oxidation processes in an electroflocculation (electrocoagulation) cell

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Sasson, Moshe Ben, E-mail: mosheinspain@hotmail.com [Department of Soil and Water Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot 76100 (Israel); Calmano, Wolfgang [Institute of Environmental Technology and Energy Economics, Technical University of Hamburg-Harburg, 21073 Hamburg (Germany); Adin, Avner [Department of Soil and Water Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot 76100 (Israel)

2009-11-15

The processes of iron oxidation in an electroflocculation cell were investigated for a pH range of 5-9 and electric currents of 0.05-0.4 A (equivalent current densities of 8.6-69 A/m{sup 2}). At all pH values and electric currents investigated, it was demonstrated and proven that for all practical purposes, the form of iron that dissolves from the anode is Fe{sup 2+} (ferrous). The difference between the amount of theoretical dissolution as calculated by Faraday's law and the amount of observed dissolved iron ions may indicate two phenomena in electrochemical cells. The first is possible dissolution of the anode even without the operation of an electric current; this led to higher theoretical dissolution rates at lower pH. The second is the participation of some of the electrons of the electric current in reactions other than anode dissolution which led to lower theoretical dissolution rates at higher pH. Those other reactions did not lead to an increase in the local oxidation saturation level near the anode and did not affect iron-oxidation rates in the electroflocculation processes. The oxidation rates of the dissolved Fe{sup 2+} (ferrous) to Fe{sup 3+} (ferric) ions in electroflocculation processes were strongly dependent on the pH and were similar to the known oxidation rates of iron in non-electrochemical cells.

Iron-oxidation processes in an electroflocculation (electrocoagulation) cell

International Nuclear Information System (INIS)

Sasson, Moshe Ben; Calmano, Wolfgang; Adin, Avner

2009-01-01

The processes of iron oxidation in an electroflocculation cell were investigated for a pH range of 5-9 and electric currents of 0.05-0.4 A (equivalent current densities of 8.6-69 A/m 2 ). At all pH values and electric currents investigated, it was demonstrated and proven that for all practical purposes, the form of iron that dissolves from the anode is Fe 2+ (ferrous). The difference between the amount of theoretical dissolution as calculated by Faraday's law and the amount of observed dissolved iron ions may indicate two phenomena in electrochemical cells. The first is possible dissolution of the anode even without the operation of an electric current; this led to higher theoretical dissolution rates at lower pH. The second is the participation of some of the electrons of the electric current in reactions other than anode dissolution which led to lower theoretical dissolution rates at higher pH. Those other reactions did not lead to an increase in the local oxidation saturation level near the anode and did not affect iron-oxidation rates in the electroflocculation processes. The oxidation rates of the dissolved Fe 2+ (ferrous) to Fe 3+ (ferric) ions in electroflocculation processes were strongly dependent on the pH and were similar to the known oxidation rates of iron in non-electrochemical cells.

IRON AND FREE RADICAL OXIDATIONS IN CELL MEMBRANES

Science.gov (United States)

Schafer, Freya Q.; Yue Qian, Steven; Buettner, Garry R.

2013-01-01

Brain tissue being rich in polyunsaturated fatty acids, is very susceptible to lipid peroxidation. Iron is well known to be an important initiator of free radical oxidations. We propose that the principal route to iron-mediated lipid peroxidations is via iron-oxygen complexes rather than the reaction of iron with hydrogen peroxide, the Fenton reaction. To test this hypothesis, we enriched leukemia cells (K-562 and L1210 cells) with docosahexaenoic acid (DHA) as a model for brain tissue, increasing the amount of DHA from approximately 3 mole % to 32 mole %. These cells were then subjected to ferrous iron and dioxygen to initiate lipid peroxidation in the presence or absence of hydrogen peroxide. Lipid-derived radicals were detected using EPR spin trapping with α-(4-pyridyl-1-oxide)-N-t-butylnitrone (POBN). As expected, lipid-derived radical formation increases with increasing cellular lipid unsaturation. Experiments with Desferal demonstrate that iron is required for the formation of lipid radicals from these cells. Addition of iron to DHA-enriched L1210 cells resulted in significant amounts of radical formation; radical formation increased with increasing amount of iron. However, the exposure of cells to hydrogen peroxide before the addition of ferrous iron did not increase cellular radical formation, but actually decreased spin adduct formation. These data suggest that iron-oxygen complexes are the primary route to the initiation of biological free radical oxidations. This model proposes a mechanism to explain how catalytic iron in brain tissue can be so destructive. PMID:10872752

COMPARATIVE STUDY OF EFFICACY OF FERROUS SULPHATE AND CARBONYL IRON IN ANEMIA OF ANTENATAL WOMEN

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Radhika

2015-03-01

Full Text Available Iron deficiency anemia is the most common and important public health problem all over the world in the risk group of antenatal women. Research is going on to improve the iron status of the pregnant women with different forms of iron available. In this regard, Carbonyl Iron is showing promising results in improving the red cell mass with better compliance. 120 antenatal women were recruited in this study. The study comprised of 6weeks for each patient. They were given Carbonyl Iron 100 mg/day and FeS04 100gm/day . Before and after treatment all the baseline and specific investigations were one. Results were tabulated, comparison and significance were tested by unpaired student ’s’ test and their 'p' value was calculated. Results were shown graphically also. Carbonyl Iron showed improvement in hemoglobin, PCV and better than ferrous Sulphate (P <0.001. Incidence of side effects were less with Carbonyl Iron than Ferrous Sulphate, better compliance was seen with Carbonyl Iron. In conclusion, the present study s howed that Carbonyl Iron had better efficacy and safety in the management of Iron deficiency anemia in antenatal women than ferrous Sulphate

Efficacy, Tolerability, and Acceptability of Iron Hydroxide Polymaltose Complex versus Ferrous Sulfate: A Randomized Trial in Pediatric Patients with Iron Deficiency Anemia

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Beril Yasa

2011-01-01

Full Text Available Iron polymaltose complex (IPC offers similar efficacy with superior tolerability to ferrous sulfate in adults, but randomized trials in children are rare. In a prospective, open-label, 4-month study, 103 children aged >6 months with iron deficiency anemia (IDA were randomized to IPC once daily or ferrous sulfate twice daily, (both 5 mg iron/kg/day. Mean increases in Hb to months 1 and 4 with IPC were 1.2±0.9 g/dL and 2.3±1.3 g/dL, respectively, (both P=0.001 versus baseline and 1.8±1.7 g/dL and 3.0±2.3 g/dL with ferrous sulfate (both P=0.001 versus baseline (n.s. between groups. Gastrointestinal adverse events occurred in 26.9% and 50.9% of IPC and ferrous sulfate patients, respectively (P=0.012. Mean acceptability score at month 4 was superior with IPC versus ferrous sulfate (1.63±0.56 versus 2.14±0.75, P=0.001. Efficacy was comparable with IPC and ferrous sulfate over a four-month period in children with IDA, but IPC was associated with fewer gastrointestinal adverse events and better treatment acceptability.

Iron-mediated anaerobic oxidation of methane in brackish coastal sediments.

Science.gov (United States)

Egger, Matthias; Rasigraf, Olivia; Sapart, Célia J; Jilbert, Tom; Jetten, Mike S M; Röckmann, Thomas; van der Veen, Carina; Bândă, Narcisa; Kartal, Boran; Ettwig, Katharina F; Slomp, Caroline P

2015-01-06

Methane is a powerful greenhouse gas and its biological conversion in marine sediments, largely controlled by anaerobic oxidation of methane (AOM), is a crucial part of the global carbon cycle. However, little is known about the role of iron oxides as an oxidant for AOM. Here we provide the first field evidence for iron-dependent AOM in brackish coastal surface sediments and show that methane produced in Bothnian Sea sediments is oxidized in distinct zones of iron- and sulfate-dependent AOM. At our study site, anthropogenic eutrophication over recent decades has led to an upward migration of the sulfate/methane transition zone in the sediment. Abundant iron oxides and high dissolved ferrous iron indicate iron reduction in the methanogenic sediments below the newly established sulfate/methane transition. Laboratory incubation studies of these sediments strongly suggest that the in situ microbial community is capable of linking methane oxidation to iron oxide reduction. Eutrophication of coastal environments may therefore create geochemical conditions favorable for iron-mediated AOM and thus increase the relevance of iron-dependent methane oxidation in the future. Besides its role in mitigating methane emissions, iron-dependent AOM strongly impacts sedimentary iron cycling and related biogeochemical processes through the reduction of large quantities of iron oxides.

Recycling of ferrous sulfate by the synthesis of a new super oxidant material 'Referox'

Energy Technology Data Exchange (ETDEWEB)

Evrard, O. [Universite Henri Poincare, Vandoeuvre (France); Dupre, B.; Jeannot, C.; Kanari, N.; Gaballah, I.; Ninane, L.; Verstraete, W.; Denomme, S.; Belsue, M.

2001-07-01

This European Union-sponsored project was initiated to develop a process to recycle industrial ferrous sulfate by the synthesis of a superoxidant containing hexavalent (FeVI) iron. Hexavalent iron, also called ferrates, can be used in decontamination of industrial effluents, decolorisation and purification of effluents from the textile and tanning industries, oxidation of cyanide to cyanates, soil remediation, water treatment and in a variety of other processes. Dry synthesis of potassium ferrate, using calcium hypochlorite as the oxidizing agent, was successful. By using chlorine instead of calcium hypochlorite and by partially substituting sodium hydroxide for potassium hydroxide the cost of the synthesis was significantly reduced. Recycling of ferrous sulfate at room temperature by the synthesis of potassium ferrate (FeVI) using gaseous chlorine instead of solid calcium hypochlorite was also successful. The yield of the synthesis was about 65 per cent for the used industrial ferrous sulfate samples. Large scale experimentation of the potassium ferrate synthesis was also carried out, obtaining potassium ferrate that remained stable for several months. The ferrates were used in the treatment of drinking water, wastewater, soil remediation, and effluent decontamination. Encouraging results were obtained. An additional benefit found was that use of the ferrates as bactericide for water treatment instead of chlorine gas eliminates the generation of halo-organic compounds which are suspected to be carcinogenic. 2 figs.

[Ferrous sulfate in the treatment of iron deficiency anemia: The positions continue].

Science.gov (United States)

Dvoretsky, L I

The paper discusses treatment strategy and tactics for iron deficiency anemia. It gives data on the comparative efficacy of different iron sulfate drugs, their bioavailability, effects on peroxidation processes, and side effects. The paper also considers the clinical significance of a dosage form of iron-containing drugs with a sustained iron release, as well as ways to reduce the frequency and magnitude of side effects when ferrous sulfate is used.

The role of iron species on the turbidity of oxidized phenol solutions in a photo-Fenton system.

Science.gov (United States)

Villota, Natalia; Camarero, Luis M; Lomas, Jose M; Perez-Arce, Jonatan

2015-01-01

This work aims at establishing the contribution of the iron species to the turbidity of phenol solutions oxidized with photo-Fenton technology. During oxidation, turbidity increases linearly with time till a maximum value, according to a formation rate that shows a dependence of second order with respect to the catalyst concentration. Next, the decrease in turbidity shows the evolution of second-order kinetics, where the kinetics constant is inversely proportional to the dosage of iron, of order 0.7. The concentration of iron species is analysed at the point of maximum turbidity, as a function of the total amount of iron. Then, it is found that using dosages FeT=0-15.0 mg/L, the majority iron species was found to be ferrous ions, indicating that its concentration increases linearly with the dosage of total iron. This result may indicate that the photo-reaction of ferric ion occurs leading to the regeneration of ferrous ion. The results, obtained by operating with initial dosages FeT=15.0 and 25.0 mg/L, suggest that ferrous ion concentration decreases while ferric ion concentration increases in a complementary manner. This fact could be explained as a regeneration cycle of the iron species. The observed turbidity is generated due to the iron being added as a catalyst and the organic matter present in the system. Later, it was found that at the point of maximum turbidity, the concentration of ferrous ions is inversely proportional to the concentration of phenol and its dihydroxylated intermediates.

Comparison of efficacy of ferrous and iron polymaltose salts in the treatment of childhood iron deficiency anemia

International Nuclear Information System (INIS)

Marwat, I.U.; Hassan, K.A.; Javed, T.; Chishti, A.L.

2013-01-01

Iron deficiency of anemia (IDA) is defined as reduced number of red blood cells, and / or reduced concentration hemoglobin (Hb) due to deficiency of iron. Treatment involves dietary modifications and inorganic iron salt supplements like ferrous sulfate (FS) or Iron polymaltose complex (IPC). The decision to select either drug rests on therapeutic efficacy, untoward side effects; cost of complete course, patient's compliance and discretion of physician. Both drugs can be prescribed in oral form. This study aimed at comparing the efficacy of two iron preparations (ferrous sulphate and iron polymaltose complex salts) in childhood iron deficiency anemia. Objective: To compare the efficacy of Ferrous Sulphate and Iron Polymaltose Complex salts in the treatment of childhood Iron Deficiency Anemia. Methodology: This randomized controlled trial was conducted at Department of Pediatric Medicine Unit-II Mayo Hospital, Lahore, for a period of 6 months. One hundred and fifty children aged 6 months to 5 years suffering from iron deficiency anemia were selected and randomly divided into two groups of 75 each (Group A and B prescribed FS and IPC respectively). Results were analyzed in terms of rise in Hb from the baseline after three months. Increase in Hb level 2 gm/dl after three months of treatment was considered as effective. Results were analyzed by SPSS version 17. Efficacy of both the drugs, was compared by chi square test. P value 0.05 was accepted as significant. Results: There were 34 cases (22.7%) in 6-12 months age, 77 cases (51.3%) between 1-3 years age and 39 cases (26%) between 3-5 years age. The number of male and female children was 82 (54.7%) and 68 (45.3%) respectively. The baseline hemoglobin of all study cases was 6.64+-1.08 gm/dl (6.59+-1.13 gm/dl in Group A and 6.69+-1.04 gm/dl in Group B). At completion of therapy, the mean hemoglobin of all study cases was 9.15+-1.21 gm/dl (9.20+9-1.17 gm/dl in Group A and 9.11+-1.25 gm/dl in Group B). The difference

The ferrous iron transporter FtrABCD is required for the virulence of Brucella abortus 2308 in mice.

Science.gov (United States)

Elhassanny, Ahmed E M; Anderson, Eric S; Menscher, Evan A; Roop, R Martin

2013-06-01

Iron transport has been linked to the virulence of Brucella strains in both natural and experimental hosts. The genes designated BAB2_0837-0840 in the Brucella abortus 2308 genome sequence are predicted to encode a CupII-type ferrous iron transporter homologous to the FtrABCD transporter recently described in Bordetella. To study the role of the Brucella FtrABCD in iron transport, an isogenic ftrA mutant was constructed from B. abortus 2308. Compared with the parental strain, the B. abortus ftrA mutant displays a decreased capacity to use non-haem iron sources in vitro, a growth defect in a low iron medium that is enhanced at pH 6, and studies employing radiolabelled FeCl3 confirmed that FtrABCD transports ferrous iron. Transcription of the ftrA gene is induced in B. abortus 2308 in response to iron deprivation and exposure to acid pH, and similar to other Brucella iron acquisition genes that have been examined the iron-responsiveness of ftrA is dependent upon the iron response regulator Irr. The B. abortus ftrA mutant exhibits significant attenuation in both cultured murine macrophages and experimentally infected mice, supporting the proposition that ferrous iron is a critical iron source for these bacteria in the mammalian host. © 2013 John Wiley & Sons Ltd.

Electron uptake by iron-oxidizing phototrophic bacteria

Energy Technology Data Exchange (ETDEWEB)

Bose, A; Gardel, EJ; Vidoudez, C; Parra, EA; Girguis, PR

2014-02-26

Oxidation-reduction reactions underlie energy generation in nearly all life forms. Although most organisms use soluble oxidants and reductants, some microbes can access solid-phase materials as electron-acceptors or -donors via extracellular electron transfer. Many studies have focused on the reduction of solid-phase oxidants. Far less is known about electron uptake via microbial extracellular electron transfer, and almost nothing is known about the associated mechanisms. Here we show that the iron-oxidizing photoautotroph Rhodopseudomonas palustris TIE-1 accepts electrons from a poised electrode, with carbon dioxide as the sole carbon source/electron acceptor. Both electron uptake and ruBisCo form I expression are stimulated by light. Electron uptake also occurs in the dark, uncoupled from photosynthesis. Notably, the pioABC operon, which encodes a protein system essential for photoautotrophic growth by ferrous iron oxidation, influences electron uptake. These data reveal a previously unknown metabolic versatility of photoferrotrophs to use extracellular electron transfer for electron uptake.

Bacterial Oxidation and Reduction of Iron in the Processes of Creation and Treatment of Acid Mining Waters

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Daniel Kupka

2004-12-01

Full Text Available Acid mine drainages (AMDs arise at the weathering of sulphidic minerals. The occurrence of acidic streams is commonly associated with the human mining activities. Due to the disruption and excavation of sulphide deposits, the oxidation processes have initiated. Acidic products of sulphide oxidation accelerate the degradation of accompanying minerals. AMDs typically contain high concentrations of sulfuric acid and soluble metals and cause serious ecological problems due to the water pollution and the devastation of adjacent country. Microbial life in these extremely acidic environments may be considerably diverse. AMDs are abundant in bacteria capable to oxidize and/or to reduce iron. The rate of bacterial oxidation of ferrous iron released from pyrite surfaces is up to one million times faster than the chemical oxidation rate at low pH. Bacterial regeneration of ferric iron maintains the continuity of pyrite oxidation and the production of AMDs. Another group of microorganisms living in these environments are acidophilic ferric iron reducing bacteria. This group of microorganisms has been discovered only relatively recently. Acidophilic heterotrophic bacteria reduce ferric iron in either soluble or solid forms to ferrous iron. The reductive dissolution of ferric iron minerals brings about a mobilization of iron as well as associated heavy metals. The Bacterial oxidation and reduction of iron play an important role in the transformation of either crystalline or amorphous iron-containing minerals, including sulphides, oxides, hydroxysulfates, carbonates and silicates. This work discusses the role of acidophilic bacteria in the natural iron cycling and the genesis of acidic effluents. The possibilities of application of iron bacteria in the remediation of AMDs are also considered.

Analytical applications of condensed phosphoric acid-I Determination of ferrous and total iron in iron ores after decomposition with condensed phosphoric acid.

Science.gov (United States)

Mizoguchi, T; Ishii, H

1978-06-01

A simple method is described for the determination of ferrous and total iron in iron ores. Iron ores are dissolved by condensed phosphoric acid (CPA) very rapidly without any tedious and time-consuming manipulations such as elimination of silica and filtration. Under the proposed conditions (amount of sample 100 mg, amount of CPA added 10 g, heating temperature 290 degrees , heating time 30 min), magnetite, limonite and hematite are completely dissolved. The iron content can be determined in the presence of condensed phosphoric acid by titration with dichromate solution, if a slight modification is made. The total iron in iron ores, determined by the present method, is in agreement with that found by the JIS method. The ferrous iron in iron ores can be determined by dissolving the samples with CPA in a nitrogen atmosphere and titrating with dichromate solution. Chelatometric titration of iron after solvent extraction with MIBK from solutions prepared by use of CPA is found to be accurate for samples such as pyrite cinder. The ability of CPA to dissolve various materials has been investigated.

Sorption of ferrous iron by EPS from the acidophilic bacterium Acidiphilium Sp.: A mechanism proposal

Energy Technology Data Exchange (ETDEWEB)

Tapia, J.M.; MuNoz, J.; Gonzlez, F.; Blazquez, M.L.; Ballester, A.

2016-07-01

The aim of this work was to assess the uptake of Fe(II) by extracellular polymeric substances (EPS) from the acidophilic bacterium Acidiphillium 3.2Sup(5). These EPS were extracted using EDTA. EPS of A. 3.2Sup(5) loaded in sorption tests with Fe(II), were characterized using the following experimental techniques: scanning electron microscopy (SEM) with energy dispersive X-ray microanalysis (EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The experimental results indicate that EPS adsorb ferrous iron according to Freundlich model with a metal sorption uptake of K = 1.14 mg1−1/n L1/n g−1 and a sorption intensity of 1/n = 1.26. In addition, ferrous iron sorption by EPS took place by preferential interaction with the carboxyl group which promotes the formation of ferrous iron oxalates (FeC2O4). Since the interaction reaction was reversible (Log K = 0.77 ± 0.33), that means that the cation sorption can be reversed at convenience. (Author)

Whey Peptide-Iron Complexes Increase the Oxidative Stability of Oil-in-Water Emulsions in Comparison to Iron Salts.

Science.gov (United States)

Caetano-Silva, Maria Elisa; Barros Mariutti, Lilian Regina; Bragagnolo, Neura; Bertoldo-Pacheco, Maria Teresa; Netto, Flavia Maria

2018-02-28

Food fortification with iron may favor lipid oxidation in both food matrices and the human body. This study aimed at evaluating the effect of peptide-iron complexation on lipid oxidation catalyzed by iron, using oil-in-water (O/W) emulsions as a model system. The extent of lipid oxidation of emulsions containing iron salts (FeSO 4 or FeCl 2 ) or iron complexes (peptide-iron complexes or ferrous bisglycinate) was evaluated during 7 days, measured as primary (peroxide value) and secondary products (TBARS and volatile compounds). Both salts catalyzed lipid oxidation, leading to peroxide values 2.6- to 4.6-fold higher than the values found for the peptide-iron complexes. The addition of the peptide-iron complexes resulted in the formation of lower amounts of secondary volatiles of lipid oxidation (up to 78-fold) than those of iron salts, possibly due to the antioxidant activity of the peptides and their capacity to keep iron apart from the lipid phase, since the iron atom is coordinated and takes part in a stable structure. The peptide-iron complexes showed potential to reduce the undesirable sensory changes in food products and to decrease the side effects related to free iron and the lipid damage of cell membranes in the organism, due to the lower reactivity of iron in the complexed form.

Ferrous Iron Up-regulation in Fibroblasts of Patients with Beta Propeller Protein-Associated Neurodegeneration (BPAN).

Science.gov (United States)

Ingrassia, Rosaria; Memo, Maurizio; Garavaglia, Barbara

2017-01-01

Mutations in WDR45 gene, coding for a beta-propeller protein, have been found in patients affected by Neurodegeneration with Brain Iron Accumulation, NBIA5 (also known as BPAN). BPAN is a movement disorder with Non Transferrin Bound Iron (NTBI) accumulation in the basal ganglia as common hallmark between NBIA classes (Hayflick et al., 2013). WDR45 has been predicted to have a role in autophagy, while the impairment of iron metabolism in the different NBIA subclasses has not currently been clarified. We found the up-regulation of the ferrous iron transporter (-)IRE/Divalent Metal Transporter1 and down-regulation of Transferrin receptor in the fibroblasts of two BPAN affected patients with splicing mutations 235+1G>A (BPAN1) and 517_519ΔVal 173 (BPAN2). The BPAN patients showed a concomitant increase of intracellular ferrous iron after starvation. An altered pattern of iron transporters with iron overload is highlighted in BPAN human fibroblasts, supporting for a role of DMT1 in NBIA. We here present a novel element, about iron accumulation, to the existing knowledge in field of NBIA. Attention is focused to a starvation-dependent iron overload, possibly accounting for iron accumulation in the basal ganglia. Further investigation could clarify iron regulation in BPAN.

Safety assessment of chronic oral exposure to iron oxide nanoparticles

International Nuclear Information System (INIS)

Chamorro, Susana; Vaquero, María Pilar; Brenes, Agustín; Gutiérrez, Lucía; Salas, Gorka; Luengo, Yurena; Verdoy, Dolores; José Teran, Francisco

2015-01-01

Iron oxide nanoparticles with engineered physical and biochemical properties are finding a rapidly increasing number of biomedical applications. However, a wide variety of safety concerns, especially those related to oral exposure, still need to be addressed for iron oxide nanoparticles in order to reach clinical practice. Here, we report on the effects of chronic oral exposure to low doses of γ-Fe 2 O 3 nanoparticles in growing chickens. Animal observation, weight, and diet intake reveal no adverse signs, symptoms, or mortality. No nanoparticle accumulation was observed in liver, spleen, and duodenum, with feces as the main excretion route. Liver iron level and duodenal villi morphology reflect the bioavailability of the iron released from the partial transformation of γ-Fe 2 O 3 nanoparticles in the acid gastric environment. Duodenal gene expression studies related to the absorption of iron from γ-Fe 2 O 3 nanoparticles indicate the enhancement of a ferric over ferrous pathway supporting the role of mucins. Our findings reveal that oral administration of iron oxide nanoparticles is a safe route for drug delivery at low nanoparticle doses. (paper)

Performance of nitrate-dependent anaerobic ferrous oxidizing (NAFO) process: a novel prospective technology for autotrophic denitrification.

Science.gov (United States)

Zhang, Meng; Zheng, Ping; Li, Wei; Wang, Ru; Ding, Shuang; Abbas, Ghulam

2015-03-01

Nitrate-dependent anaerobic ferrous oxidizing (NAFO) is a valuable biological process, which utilizes ferrous iron to convert nitrate into nitrogen gas, removing nitrogen from wastewater. In this work, the performance of NAFO process was investigated as a nitrate removal technology. The results showed that NAFO system was feasible for autotrophic denitrification. The volumetric loading rate (VLR) and volumetric removal rate (VRR) under steady state were 0.159±0.01 kg-N/(m(3) d) and 0.073±0.01 kg-N/(m(3) d), respectively. In NAFO system, the effluent pH was suggested as an indicator which demonstrated a good correlation with nitrogen removal. The nitrate concentration was preferred to be less than 130 mg-N/L. Organic matters had little influence on NAFO performance. Abundant iron compounds were revealed to accumulate in NAFO sludge with peak value of 51.73% (wt), and they could be recycled for phosphorus removal, with capacity of 16.57 mg-P/g VS and removal rate of 94.77±2.97%, respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

A procedure for oxidation during the acid leaching of non-ferrous ores, particularly uranium ores

International Nuclear Information System (INIS)

Zubcek, L.; Baloun, S.; Martinek, K.; Vebr, Z.; Krepelka, J.; Lasica, S.

1989-01-01

It is suggested that dust from the production of ferroalloys of manganese, particularly ferrosilicomanganese and ferromanganese, can be conveniently used for oxidation during the acid leaching of non-ferrous ores, particularly uranium ores. This dust contains 30 to 40% oxides of manganese, about one-half of this is MnO 2 . Iron in the dust is present in the trivalent form, and the dust is pefectly dry. The conventional grinding of oxidants for the ore processing is eliminated, the dust being available in particle size below 0.2 mm. The dust is added in amounts of 5 to 100 kg per ton of the ore, and the suspension is typically heated at 115 degC for 3.5 hr. (P.A.)

A modular continuous flow reactor system for the selective bio-oxidation of iron and precipitation of schwertmannite from mine-impacted waters.

Science.gov (United States)

Hedrich, Sabrina; Johnson, D Barrie

2012-02-01

A novel modular bioremediation system which facilitates the selective removal of soluble iron from extremely acidic (pH ∼2) metal-rich wastewaters by ferrous iron oxidation and selective precipitation of the ferric iron produced is described. In the first of the three modules, rapid ferrous iron oxidation was mediated by the recently-characterized iron-oxidizing autotrophic acidophile, "Ferrovum myxofaciens", which grew as long "streamers" within the reactor. Over 90% of the iron present in influent test liquors containing 280mg/L iron was oxidized at a dilution rate of 0.41h(-1), in a proton-consuming reaction. The ferric iron-rich solutions produced were pumped into a second reactor where controlled addition of sodium hydroxide caused the water pH to increase to 3.5 and ferric iron to precipitate as the mineral schwertmannite. Addition of a flocculating agent promoted rapid aggregation and settling of the fine-grain schwertmannite particles. A third passive module (a packed-bed bioreactor, also inoculated with "Fv. myxofaciens") acted as a polishing reactor, lowering soluble iron concentrations in the processed water to iron from a synthetic acidic (pH 2.1) mine water that contained soluble aluminum, copper, manganese and zinc in addition to iron. Schwertmannite was again produced, with little or no co-precipitation of other metals. Copyright © 2011 Elsevier Ltd. All rights reserved.

Ferrous Sulfate (Iron)

Science.gov (United States)

... are allergic to ferrous sulfate, any other medications tartrazine (a yellow dye in some processed foods and ... in, tightly closed, and out of reach of children. Store it at room temperature and away from ...

Variations of 57Fe hyperfine parameters in medicaments containing ferrous fumarate and ferrous sulfate

International Nuclear Information System (INIS)

Oshtrakh, M. I.; Novikov, E. G.; Dubiel, S. M.; Semionkin, V. A.

2010-01-01

Several commercially available medicaments containing ferrous fumarate (FeC 4 H 2 O 4 ) and ferrous sulfate (FeSO 4 ), as a source of ferrous iron, were studied using a high velocity resolution Mössbauer spectroscopy. A comparison of the 57 Fe hyperfine parameters revealed small variations for the main components in both medicaments indicating some differences in the ferrous fumarates and ferrous sulfates. It was also found that all spectra contained additional minor components probably related to ferrous and ferric impurities or to partially modified main components.

Variations of {sup 57}Fe hyperfine parameters in medicaments containing ferrous fumarate and ferrous sulfate

Energy Technology Data Exchange (ETDEWEB)

Oshtrakh, M. I., E-mail: oshtrakh@mail.utnet.ru; Novikov, E. G. [Ural Federal University (The former Ural State Technical University-UPI), Faculty of Physical Techniques and Devices for Quality Control (Russian Federation); Dubiel, S. M. [AGH University of Science and Technology, Faculty of Physics and Computer Science (Poland); Semionkin, V. A. [Ural Federal University (The former Ural State Technical University-UPI), Faculty of Physical Techniques and Devices for Quality Control (Russian Federation)

2010-04-15

Several commercially available medicaments containing ferrous fumarate (FeC{sub 4}H{sub 2}O{sub 4}) and ferrous sulfate (FeSO{sub 4}), as a source of ferrous iron, were studied using a high velocity resolution Moessbauer spectroscopy. A comparison of the {sup 57}Fe hyperfine parameters revealed small variations for the main components in both medicaments indicating some differences in the ferrous fumarates and ferrous sulfates. It was also found that all spectra contained additional minor components probably related to ferrous and ferric impurities or to partially modified main components.

Lactoferrin or ferrous salts for iron deficiency anemia in pregnancy: A meta-analysis of randomized trials.

Science.gov (United States)

Abu Hashim, Hatem; Foda, Osama; Ghayaty, Essam

2017-12-01

This systematic review and meta-analysis aimed to evaluate the efficacy of daily oral bovine lactoferrin versus daily oral ferrous iron preparations for treatment of iron deficiency anemia (IDA) during pregnancy. Searches were conducted on PubMed, ScienceDirect, ClinicalTrials.gov and CENTRAL databases from inception to February 2017 and the bibliographies of retrieved articles were screened. The PRISMA Statement was followed. Published English language randomized trials comparing lactoferrin with oral ferrous iron preparations in pregnant women with iron deficiency anemia were included. Quasi-randomized, non- randomized or studies including other known cause of anemia, gestational or pre-existent maternal diseases were excluded. Accordingly, 4 eligible trials (600 women) were analyzed. Primary outcome was change in hemoglobin level at 4 weeks of treatment. Secondary outcomes were; change in serum ferritin and iron, rates of gastrointestinal side effects, preterm birth, low birthweight, neonatal death and mean birthweight. Quality assessment was performed by the Cochrane risk of bias tool. Odds ratio and mean difference were used to integrate dichotomous and continuous outcomes respectively. Pooled estimates for change in hemoglobin levels at four weeks favored daily oral lactoferrin over daily oral ferrous sulphate (mean difference 0.77; 95% confidence interval [CI] 0.04-1.55; P=0.04, 4 trials, 600 women). However, after subgroup analysis (degree of anemia), no significant difference in hemoglobin levels were found between both groups in mild anemia (mean difference 0.80; 95% CI -0.21 to 1.82, 3 trials, 372 women), but a significant increase favoring lactoferrin was reported in moderate anemia (mean difference 0.68; 95% CI 0.53-0.83; P<0.00001, one trial, 228 women). Significantly less gastrointestinal side effects were reported with lactoferrin treatment. No significant differences existed with regard to other outcomes. In conclusion, for pregnant women with IDA

Oxidative dissolution of spent fuel and release of nuclides from a copper/iron canister. Model developments and applications

Energy Technology Data Exchange (ETDEWEB)

Longcheng Liu

2001-12-01

Three models have been developed and applied in the performance assessment of a final repository. They are based on accepted theories and experimental results for known and possible mechanisms that may dominate in the oxidative dissolution of spent fuel and the release of nuclides from a canister. Assuming that the canister is breached at an early stage after disposal, the three models describe three sub-systems in the near field of the repository, in which the governing processes and mechanisms are quite different. In the model for the oxidative dissolution of the fuel matrix, a set of kinetic descriptions is provided that describes the oxidative dissolution of the fuel matrix and the release of the embedded nuclides. In particular, the effect of autocatalytic reduction of hexavalent uranium by dissolved H{sub 2}, using UO{sub 2} (s) on the fuel pellets as a catalyst, is taken into account. The simulation results suggest that most of the radiolytic oxidants will be consumed by the oxidation of the fuel matrix, and that much less will be depleted by dissolved ferrous iron. Most of the radiolytically produced hexavalent uranium will be reduced by the autocatalytic reaction with H{sub 2} on the fuel surface. It will reprecipitate as UO{sub 2} (s) on the fuel surface, and thus very little net oxidation of the fuel will take place. In the reactive transport model, the interactions of multiple processes within a defective canister are described, in which numerous redox reactions take place as multiple species diffuse. The effect of corrosion of the cast iron insert of the canister and the reduction of dissolved hexavalent uranium by ferrous iron sorbed onto iron corrosion products and by dissolved H{sub 2} are particularly included. Scoping calculations suggest that corrosion of the iron insert will occur primarily under anaerobic conditions. The escaping oxidants from the fuel rods will migrate toward the iron insert. Much of these oxidants will, however, be consumed

Photoreductive dissolution of iron oxides trapped in ice and its environmental implications.

Science.gov (United States)

Kim, Kitae; Choi, Wonyong; Hoffmann, Michael R; Yoon, Ho-Il; Park, Byong-Kwon

2010-06-01

The availability of iron has been thought to be a main limiting factor for the productivity of phytoplankton and related with the uptake of atmospheric CO(2) and algal blooms in fresh and sea waters. In this work, the formation of bioavailable iron (Fe(II)(aq)) from the dissolution of iron oxide particles was investigated in the ice phase under both UV and visible light irradiation. The photoreductive dissolution of iron oxides proceeded slowly in aqueous solution (pH 3.5) but was significantly accelerated in polycrystalline ice, subsequently releasing more bioavailable ferrous iron upon thawing. The enhanced photogeneration of Fe(II)(aq) in ice was confirmed regardless of the type of iron oxides [hematite, maghemite (gamma-Fe(2)O(3)), goethite (alpha-FeOOH)] and the kind of electron donors. The ice-enhanced dissolution of iron oxides was also observed under visible light irradiation, although the dissolution rate was much slower compared with the case of UV radiation. The iron oxide particles and organic electron donors (if any) in ice are concentrated and aggregated in the liquid-like grain boundary region (freeze concentration effect) where protons are also highly concentrated (lower pH). The enhanced photodissolution of iron oxides should occur in this confined boundary region. We hypothesized that electron hopping through the interconnected grain boundaries of iron oxide particles facilitates the separation of photoinduced charge pairs. The outdoor experiments carried out under ambient solar radiation of Ny-Alesund (Svalbard, 78 degrees 55'N) also showed that the generation of dissolved Fe(II)(aq) via photoreductive dissolution is enhanced when iron oxides are trapped in ice. Our results imply that the ice(snow)-covered surfaces and ice-cloud particles containing iron-rich mineral dusts in the polar and cold environments provide a source of bioavailable iron when they thaw.

Bioavailability of elemental iron powders to rats is less than bakery-grade ferrous sulfate and predicted by iron solubility and particle surface area.

Science.gov (United States)

Swain, James H; Newman, Samuel M; Hunt, Janet R

2003-11-01

Foods are fortified with elemental forms of iron to reduce iron deficiency. However, the nutritional efficacy of current, commercially produced elemental iron powders has not been verified. We determined the bioavailability of six commercial elemental iron powders and examined how physicochemistry influences bioavailability. Relative biological value (RBV) of the iron powders was determined using a hemoglobin repletion/slope ratio method, treating iron-deficient rats with repletion diets fortified with graded quantities of iron powders, bakery-grade ferrous sulfate or no added iron. Iron powders were assessed physicochemically by measuring iron solubility in hydrochloric acid at pH 1.0 and 1.7, surface area by nitrogen gas adsorption and surface microstructure by electron microscopy. Bioavailability from the iron powders, based on absolute iron intake, was significantly less than from FeSO4 (100%; P Electrolytic (54%; A-131, U.S.) > Electrolytic (46%; Electrolytic Iron, India) > H-Reduced (42%; AC-325, U.S.) > Reduced (24%; ATOMET 95SP, Canada) > CO-Reduced (21%; RSI-325, Sweden). Solubility testing of the iron powders resulted in different relative rankings and better RBV predictability with increasing time at pH 1.7 (R2 = 0.65 at 150 min). The prediction was improved with less time and lower pH (R2 = 0.82, pH 1.0 at 30 min). Surface area, ranging from 90 to 370 m2/kg, was also highly predictive of RBV (R2 = 0.80). Bioavailability of iron powders is less than bakery-grade ferrous sulfate and varies up to three times among different commercial forms. Solubility at pH 1.0 and surface area were predictive of iron bioavailability in rats.

Insights into the iron and sulfur energetic metabolism of Acidithiobacillus ferrooxidans by microarray transcriptome profiling

Energy Technology Data Exchange (ETDEWEB)

R. Quatrini; C. Appia-Ayme; Y. Denis; J. Ratouchniak; F. Veloso; J. Valdes; C. Lefimil; S. Silver; F. Roberto; O. Orellana; F. Denizot; E. Jedlicki; D. Holmes; V. Bonnefoy

2006-09-01

Acidithiobacillus ferrooxidans is a well known acidophilic, chemolithoautotrophic, Gram negative, bacterium involved in bioleaching and acid mine drainage. In aerobic conditions, it gains energy mainly from the oxidation of ferrous iron and/or reduced sulfur compounds present in ores. After initial oxidation of the substrate, electrons from ferrous iron or sulfur enter respiratory chains and are transported through several redox proteins to oxygen. However, the oxidation of ferrous iron and reduced sulfur compounds has also to provide electrons for the reduction of NAD(P) that is subsequently required for many metabolic processes including CO2 fixation. To help to unravel the enzymatic pathways and the electron transfer chains involved in these processes, a genome-wide microarray transcript profiling analysis was carried out. Oligonucleotides corresponding to approximately 3000 genes of the A. ferrooxidans type strain ATCC23270 were spotted onto glass-slides and hybridized with cDNA retrotranscribed from RNA extracted from ferrous iron and sulfur grown cells. The genes which are preferentially transcribed in ferrous iron conditions and those preferentially transcribed in sulfur conditions were analyzed. The expression of a substantial number of these genes has been validated by real-time PCR, Northern blot hybridization and/or immunodetection analysis. Our results support and extend certain models of iron and sulfur oxidation and highlight previous observations regarding the possible presence of alternate electron pathways. Our findings also suggest ways in which iron and sulfur oxidation may be co-ordinately regulated. An accompanying paper (Appia-Ayme et al.) describes results pertaining to other metabolic functions.

In vitro evaluation of iron solubility and dialyzability of various iron fortificants and of iron-fortified milk products targeted for infants and toddlers.

Science.gov (United States)

Kapsokefalou, Maria; Alexandropoulou, Isidora; Komaitis, Michail; Politis, Ioannis

2005-06-01

The objectives of the present study were: to compare the solubility and dialyzability of various iron fortificants (iron pyrophosphate, ferrous bis-glycinate, ferrous gluconate, ferrous lactate, ferrous sulfate) added, in the presence of ascorbic acid, to pasteurized milk samples produced under laboratory conditions; and to compare the solubility and dialyzability of iron in commercial pasteurized, UHT and condensed milk products available in the Greek market fortified with various vitamins and minerals including iron and targeted towards infants (6-12 months old) and toddlers. Iron solubility and dialyzability were determined using a simulated gastrointestinal digestive system. Ferrous dialyzable iron (molecular weight lower than 8000) was used as an index for prediction of iron bioavailability. Ferrous dialyzable iron in pasteurized milk samples fortified with iron pyrophosphate, ferrous lactate and ferrous bis-glycinate was higher (P iron in products fortified with ferrous lactate was not different (P > 0.05) from those fortified with ferrous sulfate. Ferrous dialyzable iron in four condensed commercial milk products was higher (P iron was higher (P iron source, milk processing and the overall product composition affect formation of ferrous dialyzable iron and may determine the success and effectiveness of iron fortification of milk.

Effects of thermal treatment on mineralogy and heavy metal behavior in iron oxide stabilized air pollution control residues

DEFF Research Database (Denmark)

Sørensen, Mette Abildgaard; Bender-Koch, C.; Starckpoole, M. M.

2000-01-01

Stabilization of air pollution control residues by coprecipitation with ferrous iron and subsequent thermal treatment (at 600 and 900 °C) has been examined as a means to reduce heavy metal leaching and to improve product stability. Changes in mineralogy and metal binding were analyzed using various...... analytical and environmental techniques. Ferrihydrite was formed initially but transformed upon thermal treatment to more stable and crystalline iron oxides (maghemite and hematite). For some metals leaching studies showed more substantial binding after thermal treatment, while other metals either....... Thermal treatment of the stabilized residues produced structures with an inherently better iron oxide stability. However, the concentration of metals in the leachate generally increased as a consequence of the decreased solubility of metals in the more stable iron oxide structure....

Overview of the long distance iron ore slurry pipeline from Anglo Ferrous Brazil

Energy Technology Data Exchange (ETDEWEB)

Silva, Adarlan M.; Passos, Aline C.; Santos, Daniel; Orban, Eduardo M.; Lisboa, Helder D.; Goncalves, Nilton; Guimaraes, Robson C. [Anglo Ferrous Brazil, Rio de Janeiro, RJ (Brazil)

2009-07-01

The objective of this paper is to present an overview of the long distance iron ore slurry pipeline from Anglo Ferrous Brazil. Anglo Ferrous Brazil is a company of Anglo American plc that is one of the world's largest mining and natural resource company. Minas-Rio is a world class iron ore project which has been developed in Brazil aiming to produce 26.6 million tons per year of concentrate. The mine, concentrator and pump station 1 will be located in Conceicao do Mato Dentro, Minas Gerais state, and the terminal station will be located at Acu Port in Sao Joao da Barra, Rio de Janeiro state. The long distance iron ore slurry pipeline will be one of major differentials of Minas-Rio Project and its useful life was initially estimated in 20 years. The slurry pipeline has a total length of 525 kilometers and will be constructed from predominately 26 inches external diameter API 5L X70 pipes. From kilometer 314 to kilometer 480, 24 inches pipe will be installed to prevent slack flow downstream pump station 2. The pump station 1 is designed to provide the hydraulic head necessary to transport the concentrate iron ore slurry with 8 positive displacement pumps to pump station 2. The pump station 2, located 240 kilometers downstream pump station 1, is designed to operate with 10 positive displacement pumps. The valve station will be located at kilometer 347 and will be used to break the static head between pump station 2 and the terminal station during a slurry pipeline shutdown. (author)

Freezing-Enhanced Dissolution of Iron Oxides: Effects of Inorganic Acid Anions.

Science.gov (United States)

Jeong, Daun; Kim, Kitae; Min, Dae Wi; Choi, Wonyong

2015-11-03

Dissolution of iron from mineral dust particles greatly depends upon the type and amount of copresent inorganic anions. In this study, we investigated the roles of sulfate, chloride, nitrate, and perchlorate on the dissolution of maghemite and lepidocrocite in ice under both dark and UV irradiation and compared the results with those of their aqueous counterparts. After 96 h of reaction, the total dissolved iron in ice (pH 3 before freezing) was higher than that in the aqueous phase (pH 3) by 6-28 times and 10-20 times under dark and UV irradiation, respectively. Sulfuric acid was the most efficient in producing labile iron under dark condition, whereas hydrochloric acid induced the most dissolution of the total and ferrous iron in the presence of light. This ice-induced dissolution result was also confirmed with Arizona Test Dust (AZTD). In the freeze-thaw cycling test, the iron oxide samples containing chloride, nitrate, or perchlorate showed a similar extent of total dissolved iron after each cycling while the sulfate-containing sample rapidly lost its dissolution activity with repeating the cycle. This unique phenomenon observed in ice might be related to the freeze concentration of protons, iron oxides, and inorganic anions in the liquid-like ice grain boundary region. These results suggest that the ice-enhanced dissolution of iron oxides can be a potential source of bioavailable iron, and the acid anions critically influence this process.

Redox transformations of iron at extremely low pH: fundamental and applied aspects

Directory of Open Access Journals (Sweden)

D. Barrie eJohnson

2012-03-01

Full Text Available Many different species of acidophilic prokaryotes, widely distributed within the domains Bacteria and Archaea, can catalyze the dissimilatory oxidation of ferrous iron or reduction of ferric iron, or can do both. Microbially-mediated cycling of iron in extremely acidic environments (pH <3 is strongly influenced by the enhanced chemical stability of ferrous iron and far greater solubility of ferric iron under such conditions. Cycling of iron has been demonstrated in vitro using both pure and mixed cultures of acidophiles, and there is considerable evidence that active cycling of iron occurs in acid mine drainage streams, pit lakes and iron-rich acidic rivers, such as the Rio Tinto. Measurements of specific rates of iron oxidation and reduction by acidophilic microorganisms show that different species vary in their capacities for iron oxido-reduction, and that this is influenced by the electron donor provided and growth conditions used. These measurements, and comparison with corresponding data for oxidation of reduced sulfur compounds, also help explain why ferrous iron is usually used preferentially as an electron donor by acidophiles that can oxidize both iron and sulfur, even though the energy yield from oxidizing iron is much smaller than that available from sulfur oxidation. Iron-oxidizing acidophiles have been used in biomining (a technology that harness their abilities to accelerate the oxidative dissolution of sulfidic minerals and thereby facilitate the extraction of precious and base metals for several decades. More recently they have also been used to simultaneously remediate iron-contaminated surface and ground-waters and produce a useful mineral by-product (schwertmannite. Bioprocessing of oxidized mineral ores using acidophiles that bring about the reductive dissolution of ferric iron minerals such as goethite has also recently been demonstrated, and new biomining technologies based on this approach are being developed.

The effect of initial pH on the kinetics of ferrous-iron biooxidation at ...

African Journals Online (AJOL)

The general understanding in bioleaching of sulphide minerals is to keep pH low. A number of published articles have reported the effect of pH on biooxidation rates of ferrous-iron and/or sulphur by bioleaching microbes, although most of these studies were conducted at optimum or near optimum temperature for microbial ...

Ferrous ammonium phosphate (FeNH₄PO₄) as a new food fortificant: iron bioavailability compared to ferrous sulfate and ferric pyrophosphate from an instant milk drink.

Science.gov (United States)

Walczyk, Thomas; Kastenmayer, Peter; Storcksdieck Genannt Bonsmann, Stefan; Zeder, Christophe; Grathwohl, Dominik; Hurrell, Richard F

2013-06-01

The main purpose of this study was to establish bioavailability data in humans for the new (Fe) fortification compound ferrous ammonium phosphate (FAP), which was specially developed for fortification of difficult-to-fortify foods where soluble Fe compounds cannot be used due to their negative impact on product stability. A double-blind, randomized clinical trial with cross-over design was conducted to obtain bioavailability data for FAP in humans. In this trial, Fe absorption from FAP-fortified full-cream milk powder was compared to that from ferric pyrophosphate (FPP) and ferrous sulfate. Fe absorption was determined in 38 young women using the erythrocyte incorporation dual stable isotope technique (⁵⁷Fe, ⁵⁸Fe). Geometric mean Fe absorption from ferrous sulfate, FAP and FPP was 10.4, 7.4 and 3.3 %, respectively. Fe from FAP was significantly better absorbed from milk than Fe from FPP (p soluble reference compound (p = 0.0002). Absorption ratios of FAP and FPP relative to ferrous sulfate as a measure of relative bioavailability were 0.71 and 0.32, respectively. The results of the present studies show that replacing FPP with FAP in full-cream milk could significantly improve iron bioavailability.

Redox transformations of iron at extremely low pH: fundamental and applied aspects

OpenAIRE

Johnson, D. Barrie; Kanao, Tadayoshi; Hedrich, Sabrina

2012-01-01

Many different species of acidophilic prokaryotes, widely distributed within the domains Bacteria and Archaea, can catalyze the dissimilatory oxidation of ferrous iron or reduction of ferric iron, or can do both. Microbially-mediated cycling of iron in extremely acidic environments (pH <3) is strongly influenced by the enhanced chemical stability of ferrous iron and far greater solubility of ferric iron under such conditions. Cycling of iron has been demonstrated in vitro using both pure a...

Synthesis and Application of Carbon–Iron Oxide Microspheres’ Black Pigments in Electrophoretic Displays

Directory of Open Access Journals (Sweden)

Meng Xianwei

2010-01-01

Full Text Available Abstract Carbon–iron oxide microspheres’ black pigments (CIOMBs had been prepared via ultrasonic spray pyrolysis of aqueous solutions containing ferrous chloride and glucose. Due to the presence of carbon, CIOMBs not only exhibited remarkably acid resistance, but also could be well dispersed in both polar solvents and nonpolar solvent. Finally, dispersions of hollow CIOMBs in tetrachloroethylene had successfully been applied in electrophoretic displays.

RATES OF IRON OXIDATION AND ARSENIC SORPTION DURING GROUND WATER-SURFACE WATER MIXING AT A HAZARDOUS WASTE SITE

Science.gov (United States)

The fate of arsenic discharged from contaminated ground water to a pond at a hazardous waste site is controlled, in part, by the rate of ferrous iron oxidation-precipitation and arsenic sorption. Laboratory experiments were conducted using site-derived water to assess the impact...

Computational modeling and analysis of iron release from macrophages.

Directory of Open Access Journals (Sweden)

Alka A Potdar

2014-07-01

Full Text Available A major process of iron homeostasis in whole-body iron metabolism is the release of iron from the macrophages of the reticuloendothelial system. Macrophages recognize and phagocytose senescent or damaged erythrocytes. Then, they process the heme iron, which is returned to the circulation for reutilization by red blood cell precursors during erythropoiesis. The amount of iron released, compared to the amount shunted for storage as ferritin, is greater during iron deficiency. A currently accepted model of iron release assumes a passive-gradient with free diffusion of intracellular labile iron (Fe2+ through ferroportin (FPN, the transporter on the plasma membrane. Outside the cell, a multi-copper ferroxidase, ceruloplasmin (Cp, oxidizes ferrous to ferric ion. Apo-transferrin (Tf, the primary carrier of soluble iron in the plasma, binds ferric ion to form mono-ferric and di-ferric transferrin. According to the passive-gradient model, the removal of ferrous ion from the site of release sustains the gradient that maintains the iron release. Subcellular localization of FPN, however, indicates that the role of FPN may be more complex. By experiments and mathematical modeling, we have investigated the detailed mechanism of iron release from macrophages focusing on the roles of the Cp, FPN and apo-Tf. The passive-gradient model is quantitatively analyzed using a mathematical model for the first time. A comparison of experimental data with model simulations shows that the passive-gradient model cannot explain macrophage iron release. However, a facilitated-transport model associated with FPN can explain the iron release mechanism. According to the facilitated-transport model, intracellular FPN carries labile iron to the macrophage membrane. Extracellular Cp accelerates the oxidation of ferrous ion bound to FPN. Apo-Tf in the extracellular environment binds to the oxidized ferrous ion, completing the release process. Facilitated-transport model can

Ferrous and hemoglobin-59Fe absorption from supplemented cow milk in infants with normal and depleted iron stores

International Nuclear Information System (INIS)

Heinrich, H.C.; Gabbe, E.E.; Whang, D.H.; Bender-Goetze, C.; Schaefer, K.H.; Hamburg Univ.

1975-01-01

Small amounts of milk do inhibit ferrous iron absorption from a 5 mg 59 Fe 2+ dose in 1- to 18-month-old infants. Only 50 ml of 2/3 cow milk reduced the absorption from 18 to 3.8% in infants with normal iron stores (inhibition index 0.21) and from 26 to 8.5% in [de

Efficient Low-pH Iron Removal by a Microbial Iron Oxide Mound Ecosystem at Scalp Level Run.

Science.gov (United States)

Grettenberger, Christen L; Pearce, Alexandra R; Bibby, Kyle J; Jones, Daniel S; Burgos, William D; Macalady, Jennifer L

2017-04-01

Acid mine drainage (AMD) is a major environmental problem affecting tens of thousands of kilometers of waterways worldwide. Passive bioremediation of AMD relies on microbial communities to oxidize and remove iron from the system; however, iron oxidation rates in AMD environments are highly variable among sites. At Scalp Level Run (Cambria County, PA), first-order iron oxidation rates are 10 times greater than at other coal-associated iron mounds in the Appalachians. We examined the bacterial community at Scalp Level Run to determine whether a unique community is responsible for the rapid iron oxidation rate. Despite strong geochemical gradients, including a >10-fold change in the concentration of ferrous iron from 57.3 mg/liter at the emergence to 2.5 mg/liter at the base of the coal tailings pile, the bacterial community composition was nearly constant with distance from the spring outflow. Scalp Level Run contains many of the same taxa present in other AMD sites, but the community is dominated by two strains of Ferrovum myxofaciens , a species that is associated with high rates of Fe(II) oxidation in laboratory studies. IMPORTANCE Acid mine drainage pollutes more than 19,300 km of rivers and streams and 72,000 ha of lakes worldwide. Remediation is frequently ineffective and costly, upwards of $100 billion globally and nearly $5 billion in Pennsylvania alone. Microbial Fe(II) oxidation is more efficient than abiotic Fe(II) oxidation at low pH (P. C. Singer and W. Stumm, Science 167:1121-1123, 1970, https://doi.org/10.1126/science.167.3921.1121). Therefore, AMD bioremediation could harness microbial Fe(II) oxidation to fuel more-cost-effective treatments. Advances will require a deeper understanding of the ecology of Fe(II)-oxidizing microbial communities and the factors that control their distribution and rates of Fe(II) oxidation. We investigated bacterial communities that inhabit an AMD site with rapid Fe(II) oxidation and found that they were dominated by two

Fast and effective analysis of ferrous and non-ferrous alloys by X-ray fluorescence

International Nuclear Information System (INIS)

Gomez Serra, Abelardo

1987-01-01

An empirical method for the integral analysis of any kind of alloys, ferrous and non-ferrous, is described. The method is based on the intensities relation of the mixed elements and is independent of the size, shape and presentation of the sample. By this procedure, alloys with iron, copper, aluminium or magnesium base can be fastly classified. (S.M.) [es

Bacteria-assisted preparation of nano α-Fe2O3 red pigment powders from waste ferrous sulfate

International Nuclear Information System (INIS)

Li, Xiang; Wang, Chuankai; Zeng, Yu; Li, Panyu; Xie, Tonghui; Zhang, Yongkui

2016-01-01

Highlights: • A route to prepare nano α-Fe 2 O 3 red pigment from waste ferrous sulfate is proposed. • Acidithiobacillus ferrooxidans is introduced for accelerating iron oxidation. • The particle size of synthetic α-Fe 2 O 3 is ranged from 22 nm to 86 nm. • The prepared nano α-Fe 2 O 3 red pigment fulfills ISO 1248-2006. - Abstract: Massive ferrous sulfate with excess sulfuric acid is produced in titanium dioxide industry each year, ending up stockpiled or in landfills as solid waste, which is hazardous to environment and in urgent demand to be recycled. In this study, waste ferrous sulfate was used as a second raw material to synthesize nano α-Fe 2 O 3 red pigment powders with a bacteria-assisted oxidation process by Acidithiobacillus ferrooxidans. The synthesis route, mainly consisting of bio-oxidation, precipitation and calcination, was investigated by means of titration, thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray fluorescence (XRF) to obtain optimum conditions. Under the optimum conditions, nano α-Fe 2 O 3 red pigment powders contained 98.24 wt.% of Fe 2 O 3 were successfully prepared, with a morphology of spheroidal and particle size ranged from 22 nm to 86 nm and averaged at 45 nm. Moreover, the resulting product fulfilled ISO 1248-2006, the standards of iron oxide pigments.

Production of ferrous sulfate from residue from the iron mining; Producao de sulfato ferroso a partir de residuo proveniente da mineracao de ferro

Energy Technology Data Exchange (ETDEWEB)

Cardoso, K.A; Riella, H.G.; Abreu, E.F. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Engrenharia Quimica; Carvalho, E.F. Urano de; Durazzo, M. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Combustivel Nuclear

2012-11-15

This paper was developed from a residue obtained by processing iron ore exploited by the mining company Samarco S/A. The residue was characterized and the analyses showed that it contains about 70% of the mineral hematite (Fe{sub 2}O{sub 3}) and also that some economically important products could be produced. One is the ferrous sulfate that can be used in pharmaceuticals and also that can be used in the treatment of iron deficiency anemia. The iron, in addition to is importance for the industrial production of steel and parts in general, also has great biological importance in all living beings. In order to produce ferrous sulfate from the byproduct in question, it was developed a obtaining route using metallic iron as hematite reductor and sulfuric acid to form the salt. (author)

Absorption mechanisms for cationic and anionic mineral species on ferric iron polymer hydroxides and oxidation products of ferrous iron in aqueous media

International Nuclear Information System (INIS)

Gandon, Remi

1982-01-01

Adsorbents obtained by hydrolysing the Fe 3+ , 6H 2 O ion are made of polymers with aquo (H 2 O), hydroxo (-OH...) and oxo (...O...) ligands. Radioactive tracers reveal the importance of chemical mechanisms in adsorption phenomena on ferric oxide in aqueous media. Zn 2+ , Co 2+ and Mn 2+ cations are exchanged with hydrogen from hydroxo groups. CrO 4 2- , SeO 3 2- and Sb(OH) 6 - anions form covalent associations in place of iron ligands. The adsorption of hydrolyzed ions results in strong oxygen bridge bonds. In fresh water, Co and Mn participate alone in physical electrostatic adsorption. Iron II oxidation products generate chemical adsorptions. Zn 2+ and Sb(OH) 6 - associate with ferric hydroxides from oxidized Fe 2+ . 60 Co, 54 Mn and 51 Cr form covalent associations between unpaired 3d iron electrons and the adsorbed element. This process is not predominant with selenium IV or VI reduced to the metallic state or fixed on ferric hydroxide in the selenite form. These conclusions can be applied to pollutant analysis and to water purification and contribute to our understanding of the role of iron in the distribution of oligo-elements in aqueous media. (author) [fr

Treatment of highly polluted groundwater by novel iron removal process.

Science.gov (United States)

Sim, S J; Kang, C D; Lee, J W; Kim, W S

2001-01-01

The removal of ferrous iron (Fe(II)) in groundwater has been generally achieved by simple aeration, or the addition of an oxidizing agent. Aeration has been shown to be very efficient in insolubilization ferrous iron at a pH level greater than 6.5. In this study, pH was maintained over 6.5 using limestone granules under constant aeration to oxidize ferrous iron in groundwater in a limestone packed column. A sedimentation unit coupled with a membrane filtration was also developed to precipitate and filtrate the oxidized ferric compound simultaneously. Several bench-scale studies, including the effects of the limestone granule sizes, amounts and hydraulic retention time on iron removal in the limestone packed column were investigated. It was found that 550 g/L of the 7-8 mesh size limestone granules, and 20 min of hydraulic retention time in the limestone packed column, were necessary for the sufficient oxidation of 40 mg/L of iron(II) in groundwater. Long-term operation was successfully achieved in contaminated waters by removing the iron deposits on the surface of the limestone granule by continuous aeration from the bottom of the column. Periodic reverse flow helped to remove caking and fouling of membrane surface caused by the continuous filtration. Recycling of the treated water from the membrane right after reverse flow operation made possible an admissible limit of iron concentration of the treated water for drinking. The pilot-scale process was constructed and has been tested in the rural area of Korea.

Reaction mechanisms and evaluation of effective process operation for catalytic oxidation and coagulation by ferrous solution and hydrogen peroxide

Energy Technology Data Exchange (ETDEWEB)

Lee, S.H.; Moon, H.J.; Kim, Y.M. [Dept. of Environmental Engineering, Sangmyung Univ., Cheonan (Korea); Bae, W.K. [Dept. of Civil and Environmental Engineering, Hanyang Univ., Ansan, Kyounggi (Korea)

2003-07-01

This research was carried out to evaluate the removal efficiencies of COD{sub cr} and colour for the dyeing wastewater by ferrous solution and the different dosage of H{sub 2}O{sub 2} in Fenton process. In the case of H{sub 2}O{sub 2} divided dosage, 7:3 was more effective than 3:7 to remove COD{sub cr} and colour. The results showed that COD was mainly removed by Fenton coagulation, where the ferric ions are formed in the initial step of Fenton reaction. On the other hand colour was removed by Fenton oxidation rather than Fenton coagulation. This paper also aims at pursuing to investigate the effective removal mechanisms using ferrous ion coagulation, ferric ion coagulation and Fenton oxidation process. The removal mechanism of COD{sub cr} and colour was mainly coagulation by ferrous ion, ferric ion and Fenton oxidation. The removal efficiencies were dependent on the ferric ion amount at the beginning of the reaction. However the final removal efficiency of COD and colour was in the order of Fenton oxidation, ferric ion coagulation and ferrous ion coagulation. The reason of the highest removal efficiency by Fenton oxidation can be explained by the chain reactions with ferrous solution, ferric ion and hydrogen peroxide. (orig.)

[Effectiveness of iron amino acid chelate versus ferrous sulfate as part of a food complement in preschool children with iron deficiency, Medellín, 2011].

Science.gov (United States)

Rojas, Maylen Liseth; Sánchez, Juliana; Villada, Óscar; Montoya, Liliana; Díaz, Alejandro; Vargas, Cristian; Chica, Javier; Herrera, Ana Milena

2013-01-01

Iron depleted deposits are the first link in the chain of events leading to iron deficiency which is the most prevalent nutritional shortage and main cause of anemia worldwide. This situation can be prevented through food fortification. To compare the efficacy of amino acid chelate iron with ferrous sulfate as fortifier of a dietary complement in preschoolers with iron deficiency. This study was a blinded clinical trial with randomized groups. We analyzed 56 preschoolers with iron deficiency (ferritin children had respiratory tract infection, without statistical differences. Both compounds increased serum ferritin concentration, with a higher increase in those who were given milk with iron amino acid chelate. There were no differences in the adverse reactions and infections incidences between the groups.

A novel nanostructured iron oxide-gold bioelectrode for hydrogen peroxide sensing

Energy Technology Data Exchange (ETDEWEB)

Thandavan, Kavitha; Gandhi, Sakthivel; Sethuraman, Swaminathan; Krishnan, Uma Maheswari [Centre for Nanotechnology and Advanced Biomaterials, School of Chemical and Biotechnology, SASTRA University, Thanjavur 613 401 (India); Rayappan, John Bosco Balaguru, E-mail: umakrishnan@sastra.edu [Centre for Nanotechnology and Advanced Biomaterials, School of Electrical and Electronics Engineering, SASTRA University, Thanjavur 613 401 (India)

2011-07-01

Fe{sub 3}O{sub 4} nanoparticles covalently linked to a gold electrode have been used for immobilizing catalase (CAT) enzyme to sense the presence of various concentrations of H{sub 2}O{sub 2}. These nanoparticles ranging from 20 to 30 nm were synthesized by thermal co-precipitation of ferric and ferrous chlorides. SEM and XRD have been used for morphological and structural characterization of Fe{sub 3}O{sub 4} nanoparticles. CAT enzyme was linked covalently to the surface of iron oxide using carbodiimide in phosphate buffer (pH 7.4) at 4 deg. C. The enzyme-iron oxide link was confirmed by FT-IR spectroscopy. Sensing studies carried out using cyclic voltammetry showed a linear response of the CAT/nano Fe{sub 3}O{sub 4}/Au bioelectrode towards H{sub 2}O{sub 2} between 1.5 and 13.5 {mu}M with a very sharp response time of 2 s.

The production of iron oxide during peridotite serpentinization: Influence of pyroxene

Directory of Open Access Journals (Sweden)

Ruifang Huang

2017-11-01

Full Text Available Serpentinization produces molecular hydrogen (H2 that can support communities of microorganisms in hydrothermal fields; H2 results from the oxidation of ferrous iron in olivine and pyroxene into ferric iron, and consequently iron oxide (magnetite or hematite forms. However, the mechanisms that control H2 and iron oxide formation are poorly constrained. In this study, we performed serpentinization experiments at 311 °C and 3.0 kbar on olivine (with <5% pyroxene, orthopyroxene, and peridotite. The results show that serpentine and iron oxide formed when olivine and orthopyroxene individually reacted with a saline starting solution. Olivine-derived serpentine had a significantly lower FeO content (6.57 ± 1.30 wt.% than primary olivine (9.86 wt.%, whereas orthopyroxene-derived serpentine had a comparable FeO content (6.26 ± 0.58 wt.% to that of primary orthopyroxene (6.24 wt.%. In experiments on peridotite, olivine was replaced by serpentine and iron oxide. However, pyroxene transformed solely to serpentine. After 20 days, olivine-derived serpentine had a FeO content of 8.18 ± 1.56 wt.%, which was significantly higher than that of serpentine produced in olivine-only experiments. By contrast, serpentine after orthopyroxene had a slightly higher FeO content (6.53 ± 1.01 wt.% than primary orthopyroxene. Clinopyroxene-derived serpentine contained a significantly higher FeO content than its parent mineral. After 120 days, the FeO content of olivine-derived serpentine decreased significantly (5.71 ± 0.35 wt.%, whereas the FeO content of orthopyroxene-derived serpentine increased (6.85 ± 0.63 wt.% over the same period. This suggests that iron oxide preferentially formed after olivine serpentinization. Pyroxene in peridotite gained some Fe from olivine during the serpentinization process, which may have led to a decrease in iron oxide production. The correlation between FeO content and SiO2 or Al2O3 content in olivine- and

Iron absorption studies

International Nuclear Information System (INIS)

Ekenved, G.

1976-01-01

The main objective of the present work was to study iron absorption from different iron preparations in different types of subjects and under varying therapeutic conditions. The studies were performed with different radioiron isotope techniques and with a serum iron technique. The preparations used were solutions of ferrous sulphate and rapidly-disintegrating tablets containing ferrous sulphate, ferrous fumarate and ferrous carbonate and a slow-release ferrous sulphate tablet of an insoluble matrix type (Duroferon Durules). The serum iron method was evaluated and good correlation was found between the serum iron response and the total amount of iron absorbed after an oral dose of iron given in solution or in tablet form. New technique for studying the in-vivo release properties of tablets was presented. Iron tablets labelled with a radio-isotope were given to healthy subjects. The decline of the radioactivity in the tablets was followed by a profile scanning technique applied to different types of iron tablets. The release of iron from the two types of tablets was shown to be slower in vivo than in vitro. It was found that co-administration of antacids and iron tablets led to a marked reduction in the iron absorption and that these drugs should not be administered sumultaneously. A standardized meal markedly decreased the absorbability of iron from iron tablets. The influence of the meal was more marked with rapidly-disintegrating than with slow-release ferrous sulphate tablets. The absorption from rapidly-disintegrating and slow-release ferrous sulphate tablets was compared under practical clinical conditions during an extended treatment period. The studies were performed in healthy subjects, blood donors and patients with iron deficiency anaemia and it was found that the absorption of iron from the slow-release tablets was significantly better than from the rapidly-disintegrating tablets in all three groups of subjects. (author)

Population dynamics of iron-oxidizing communities in pilot plants for the treatment of acid mine waters.

Science.gov (United States)

Heinzel, Elke; Janneck, Eberhard; Glombitza, Franz; Schlömann, Michael; Seifert, Jana

2009-08-15

The iron-oxidizing microbial community in two pilot plants for the treatment of acid mine water was monitored to investigate the influence of different process parameters such as pH, iron concentration, and retention time on the stability of the system to evaluate the applicability of this treatment technology on an industrial scale. The dynamics of the microbial populations were followed using T-RFLP (terminal restriction fragment length polymorphism) over a period of several months. For a more precise quantification, two TaqMan assays specific for the two prominent groups were developed and the relative abundance of these taxa in the iron-oxidizing community was verified by real-time PCR. The investigations revealed that the iron-oxidizing community was clearly dominated by two groups of Betaproteobacteria affiliated with the poorly known and not yet recognized species "Ferrovum myxofaciens" and with strains related to Gallionella ferruginea, respectively. These taxa dominated the microbial community during the whole investigation period and accelerated the oxidation of ferrous iron despite the changing characteristics of mine waters flowing into the plants. Thus, it is assumed that the treatment technology can also be applied to other mine sites and that these organisms play a crucial role in such treatment systems.

Iron-Mediated Lysosomal Membrane Permeabilization in Ethanol-Induced Hepatic Oxidative Damage and Apoptosis: Protective Effects of Quercetin

Directory of Open Access Journals (Sweden)

Yanyan Li

2016-01-01

Full Text Available Iron, in its free ferrous states, can catalyze Fenton reaction to produce OH∙, which is recognized as a crucial role in the pathogenesis of alcoholic liver diseases (ALD. As a result of continuous decomposition of iron-containing compounds, lysosomes contain a pool of redox-active iron. To investigate the important role of intralysosomal iron in alcoholic liver injury and the potential protection of quercetin, male C57BL/6J mice fed by Lieber De Carli diets containing ethanol (30% of total calories were cotreated by quercetin or deferoxamine (DFO for 15 weeks and ethanol-incubated mice primary hepatocytes were pretreated with FeCl3, DFO, and bafilomycin A1 at their optimal concentrations and exposure times. Chronic ethanol consumption caused an evident increase in lysosomal redox-active iron accompanying sustained oxidative damage. Iron-mediated ROS could trigger lysosomal membrane permeabilization (LMP and subsequent mitochondria apoptosis. The hepatotoxicity was attenuated by reducing lysosomal iron while being exacerbated by escalating lysosomal iron. Quercetin substantially alleviated the alcoholic liver oxidative damage and apoptosis by decreasing lysosome iron and ameliorating iron-mediated LMP, which provided a new prospective of the use of quercetin against ALD.

Design of Magnetic Gelatine/Silica Nanocomposites by Nanoemulsification: Encapsulation versus in Situ Growth of Iron Oxide Colloids

Directory of Open Access Journals (Sweden)

Joachim Allouche

2014-07-01

Full Text Available The design of magnetic nanoparticles by incorporation of iron oxide colloids within gelatine/silica hybrid nanoparticles has been performed for the first time through a nanoemulsion route using the encapsulation of pre-formed magnetite nanocrystals and the in situ precipitation of ferrous/ferric ions. The first method leads to bi-continuous hybrid nanocomposites containing a limited amount of well-dispersed magnetite colloids. In contrast, the second approach allows the formation of gelatine-silica core-shell nanostructures incorporating larger amounts of agglomerated iron oxide colloids. Both magnetic nanocomposites exhibit similar superparamagnetic behaviors. Whereas nanocomposites obtained via an in situ approach show a strong tendency to aggregate in solution, the encapsulation route allows further surface modification of the magnetic nanocomposites, leading to quaternary gold/iron oxide/silica/gelatine nanoparticles. Hence, such a first-time rational combination of nano-emulsion, nanocrystallization and sol-gel chemistry allows the elaboration of multi-component functional nanomaterials. This constitutes a step forward in the design of more complex bio-nanoplatforms.

Pentachlorophenol dechlorination with zero valent iron: a Raman and GCMS study of the complex role of surficial iron oxides.

Science.gov (United States)

Gunawardana, Buddhika; Swedlund, Peter J; Singhal, Naresh; Nieuwoudt, Michel K

2018-04-20

The dechlorination of chlorinated organic pollutants by zero valent iron (ZVI) is an important water treatment process with a complex dependence on many variables. This complexity means that there are reported inconsistencies in terms of dechlorination with ZVI and the effect of ZVI acid treatment, which are significant and are as yet unexplained. This study aims to decipher some of this complexity by combining Raman spectroscopy with gas chromatography-mass spectrometry (GC-MS) to investigate the influence of the mineralogy of the iron oxide phases on the surface of ZVI on the reductive dechlorination of pentachlorophenol (PCP). Two electrolytic iron samples (ZVI-T and ZVI-H) were found to have quite different PCP dechlorination reactivity in batch reactors under anoxic conditions. Raman analysis of the "as-received" ZVI-T indicated the iron was mainly covered with the ferrous oxide (FeO) wustite, which is non-conducting and led to a low rate of PCP dechlorination. In contrast, the dominant oxide on the "as-received" ZVI-H was magnetite which is conducting and, compared to ZVI-T, the ZVI-H rate of PCP dechlorination was four times faster. Treating the ZVI-H sample with 1 N H 2 SO 4 made small change to the composition of the oxide layers and also minute change to the rate of PCP dechlorination. However, treating the ZVI-T sample with H 2 SO 4 led to the loss of wustite so that magnetite became the dominant oxide and the rate of PCP dechlorination increased to that of the ZVI-H material. In conclusion, this study clearly shows that iron oxide mineralogy can be a contributing factor to apparent inconsistencies in the literature related to ZVI performance towards dechlorination and the effect of acid treatment on ZVI reactivity.

Stabilization of Pb and As in soils by applying combined treatment with phosphates and ferrous iron.

Science.gov (United States)

Xenidis, Anthimos; Stouraiti, Christina; Papassiopi, Nymphodora

2010-05-15

The chemical immobilization of Pb and As in contaminated soil from Lavrion, Greece, using monocalcium phosphate and ferrous sulfate as stabilizing agents was investigated. Monocalcium phosphate was added to contaminated soil at PO(4) to Pb molar ratios equal to 0, 0.5, 1, 1.5 and 2.5, whereas ferrous sulfate was added at Fe to As molar ratios equal to 0, 2.5, 5, 10 and 20. Phosphates addition to contaminated soil decreased Pb leachability, but resulted in significant mobilization of As. Simultaneous immobilization of Pb and As was obtained only when soil was treated with mixtures of phosphates and ferrous sulfate. Arsenic uptake by plants was also seen to increase when soil was treated only with phosphates, but co-addition of ferrous sulfate was efficient in maintaining As phytoaccumulation at low levels. The addition of at least 1.5M/M phosphates and 10M/M iron sulfate to soil reduced the dissolved levels of Pb and As in the water extracts to values in compliance with the EU drinking water standards. However, both additives contributed in the acidification of soil, decreasing pH from 7.8 to values as low as 5.6 and induced the mobilization of pH sensitive elements, such as Zn and Cd. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Higher iron bioavailability of a human-like collagen iron complex.

Science.gov (United States)

Zhu, Chenhui; Yang, Fan; Fan, Daidi; Wang, Ya; Yu, Yuanyuan

2017-07-01

Iron deficiency remains a public health problem around the world due to low iron intake and/or bioavailability. FeSO 4 , ferrous succinate, and ferrous glycinate chelate are rich in iron but have poor bioavailability. To solve the problem of iron deficiency, following previous research studies, a thiolated human-like collagen-ironcomplex supplement with a high iron content was prepared in an anaerobic workstation. In addition, cell viability tests were evaluated after conducting an MTT assay, and a quantitative analysis of the thiolated human-like collagen-iron digesta samples was performed using the SDS-PAGE method coupled with gel filtration chromatography. The iron bioavailability was assessed using Caco-2 cell monolayers and iron-deficiency anemia mice models. The results showed that (1) one mole of thiolated human-like collagen-iron possessed approximately 35.34 moles of iron; (2) thiolated human-like collagen-iron did not exhibit cytotoxity and (3) thiolated human-like collagen- iron digesta samples had higher bioavailability than other iron supplements, including FeSO 4 , ferrous succinate, ferrous glycine chelate and thiolated human-like collagen-Fe iron. Finally, the iron bioavailability was significantly enhanced by vitamin C. These results indicated that thiolated human-like collagen-iron is a promising iron supplement for use in the future.

Characterization of incubation experiments and development of an enrichment culture capable of ammonium oxidation under iron reducing conditions

Science.gov (United States)

Huang, S.; Jaffé, P. R.

2014-08-01

Incubation experiments were conducted using soil samples from a forested riparian wetland where we have previously observed anaerobic ammonium oxidation coupled to iron reduction. Production of both nitrite and ferrous iron were measured repeatedly during incubations when the soil slurry was supplied with either ferrihydrite or goethite and ammonium chloride. Significant changes in the microbial community were observed after 180 days of incubation as well as in a continuous flow membrane reactor, using 16S rRNA gene PCR-denaturing gradient gel electrophoresis, 454-pyrosequencing, and real-time quantitative PCR analysis. We believe that one of the dominant microbial species in our system (an uncultured Acidimicrobiaceae bacterium A6), belonging to the Acidimicrobiaceae family, whose closest cultivated relative is Ferrimicrobium acidiphilum (with 92% identity) and Acidimicrobium ferrooxidans (with 90% identity), might play a key role in this anaerobic biological process that uses ferric iron as an electron acceptor while oxidizing ammonium to nitrite. After ammonium was oxidized to nitrite, nitrogen loss proceeded via denitrification and/or anammox.

Characterization of incubation experiments and development of an enrichment culture capable of ammonium oxidation under iron-reducing conditions

Science.gov (United States)

Huang, S.; Jaffé, P. R.

2015-02-01

Incubation experiments were conducted using soil samples from a forested riparian wetland where we have previously observed anaerobic ammonium oxidation coupled to iron reduction. Production of both nitrite and ferrous iron was measured repeatedly during incubations when the soil slurry was supplied with either ferrihydrite or goethite and ammonium chloride. Significant changes in the microbial community were observed after 180 days of incubation as well as in a continuous flow membrane reactor, using 16S rRNA gene PCR-denaturing gradient gel electrophoresis, 454 pyrosequencing, and real-time quantitative PCR analysis. We be Acidimicrobiaceae bacterium A6), belonging to the Acidimicrobiaceae family, whose closest cultivated relative is Ferrimicrobium acidiphilum (with 92% identity) and Acidimicrobium ferrooxidans (with 90% identity), might play a key role in this anaerobic biological process that uses ferric iron as an electron acceptor while oxidizing ammonium to nitrite. After ammonium was oxidized to nitrite, nitrogen loss proceeded via denitrification and/or anammox.

Magnetic and Moessbauer-spectroscopic studies of iron-clusters in zeolites. [Reduction of ferrous ions

Energy Technology Data Exchange (ETDEWEB)

Schmidt, F; Gunsser, W; Knappwost, A [Hamburg Univ. (F.R. Germany). Inst. fuer Physikalische Chemie

1975-12-01

Iron clusters have been prepared within zeolite holes by reduction of zeolites containing ferrous ions. The diameter of these particles must therefore be smaller that 13 A. They are superparamagnetic and their Moessbauer spectra show no HFS, even at 4K. The temperature dependence of the magnetic susceptibility of the unreduced zeolites obeys a Curie-Weiss law with p/sub eff/ = 4.45 ..mu..B and THETA = 105K. The Weiss curves of the reduced samples lie distinctly below those of the bulk material.

Bacteria-assisted preparation of nano α-Fe{sub 2}O{sub 3} red pigment powders from waste ferrous sulfate

Energy Technology Data Exchange (ETDEWEB)

Li, Xiang; Wang, Chuankai; Zeng, Yu; Li, Panyu; Xie, Tonghui; Zhang, Yongkui, E-mail: zhangyongkui@scu.edu.cn

2016-11-05

Highlights: • A route to prepare nano α-Fe{sub 2}O{sub 3} red pigment from waste ferrous sulfate is proposed. • Acidithiobacillus ferrooxidans is introduced for accelerating iron oxidation. • The particle size of synthetic α-Fe{sub 2}O{sub 3} is ranged from 22 nm to 86 nm. • The prepared nano α-Fe{sub 2}O{sub 3} red pigment fulfills ISO 1248-2006. - Abstract: Massive ferrous sulfate with excess sulfuric acid is produced in titanium dioxide industry each year, ending up stockpiled or in landfills as solid waste, which is hazardous to environment and in urgent demand to be recycled. In this study, waste ferrous sulfate was used as a second raw material to synthesize nano α-Fe{sub 2}O{sub 3} red pigment powders with a bacteria-assisted oxidation process by Acidithiobacillus ferrooxidans. The synthesis route, mainly consisting of bio-oxidation, precipitation and calcination, was investigated by means of titration, thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray fluorescence (XRF) to obtain optimum conditions. Under the optimum conditions, nano α-Fe{sub 2}O{sub 3} red pigment powders contained 98.24 wt.% of Fe{sub 2}O{sub 3} were successfully prepared, with a morphology of spheroidal and particle size ranged from 22 nm to 86 nm and averaged at 45 nm. Moreover, the resulting product fulfilled ISO 1248-2006, the standards of iron oxide pigments.

Inhibition of cellulase-catalyzed lignocellulosic hydrolysis by iron and oxidative metal ions and complexes.

Science.gov (United States)

Tejirian, Ani; Xu, Feng

2010-12-01

Enzymatic lignocellulose hydrolysis plays a key role in microbially driven carbon cycling and energy conversion and holds promise for bio-based energy and chemical industries. Cellulases (key lignocellulose-active enzymes) are prone to interference from various noncellulosic substances (e.g., metal ions). During natural cellulolysis, these substances may arise from other microbial activities or abiotic events, and during industrial cellulolysis, they may be derived from biomass feedstocks or upstream treatments. Knowledge about cellulolysis-inhibiting reactions is of importance for the microbiology of natural biomass degradation and the development of biomass conversion technology. Different metal ions, including those native to microbial activity or employed for biomass pretreatments, are often tested for enzymatic cellulolysis. Only a few metal ions act as inhibitors of cellulases, which include ferrous and ferric ions as well as cupric ion. In this study, we showed inhibition by ferrous/ferric ions as part of a more general effect from oxidative (or redox-active) metal ions and their complexes. The correlation between inhibition and oxidation potential indicated the oxidative nature of the inhibition, and the dependence on air established the catalytic role that iron ions played in mediating the dioxygen inhibition of cellulolysis. Individual cellulases showed different susceptibilities to inhibition. It is likely that the inhibition exerted its effect more on cellulose than on cellulase. Strong iron ion chelators and polyethylene glycols could mitigate the inhibition. Potential microbiological and industrial implications of the observed effect of redox-active metal ions on enzymatic cellulolysis, as well as the prevention and mitigation of this effect in industrial biomass conversion, are discussed.

Iron isotope biogeochemistry of Neoproterozoic marine shales

Science.gov (United States)

Kunzmann, Marcus; Gibson, Timothy M.; Halverson, Galen P.; Hodgskiss, Malcolm S. W.; Bui, Thi Hao; Carozza, David A.; Sperling, Erik A.; Poirier, André; Cox, Grant M.; Wing, Boswell A.

2017-07-01

, allowing a higher degree of partial oxidation, irrespective of increasing environmental oxygen levels. Alternatively, increasing oxygen levels would have led to a higher proportion of Fe(II) being oxidized, without decreasing the initial size of the ferrous seawater iron pool. We consider the latter explanation as the most likely. According to this hypothesis, the δ 56Fe record reflects the redox evolution of Earth's surface environments. δ 56Fe values in pre-Sturtian samples significantly heavier than bulk crust and hydrothermal iron imply partial oxidation of a ferrous seawater iron reservoir. In contrast, mean δ 56Fe values closer to that of hydrothermal iron in post-Sturtian shales reflects oxidation of a larger proportion of the ferrous seawater iron reservoir, and by inference, higher environmental oxygen levels. Nevertheless, significant iron isotopic variation in post-Sturtian shales suggest redox heterogeneity and possibly a dominantly anoxic deep ocean, consistent with results from recent studies using iron speciation and redox sensitive trace metals. However, the interpretation of generally increasing environmental oxygen levels after the Sturtian glaciation highlights the need to better understand the sensitivity of different redox proxies to incremental changes in oxygen levels to enable us to reconcile results from different paleoredox proxies.

The effect of change in pH on the solubility of iron bis-glycinate chelate and other iron compounds.

Science.gov (United States)

García-Casal, M N; Layrisse, M

2001-03-01

The effect of a pH change from 2 to 6 was tested on the solubility of ferrous sulfate, ferrous fumarate, iron bis-glycine chelate (Ferrochel) and sodium-iron ethylenediaminetetraacetic acid (NaFeEDTA). It was found that at pH 2 ferrous sulfate, Ferrochel and NaFeEDTA were completely soluble and only 75% of iron from ferrous fumarate was soluble. When pH was raised to 6, iron from amino acid chelate and NaFeEDTA remained completely soluble while solubility from ferrous sulfate and ferrous fumarate decreased 64 and 74%, respectively compared to the amount of iron initially soluble at pH 2. These results suggest that iron solubility from iron bis-glycine chelate and NaFeEDTA is not affected by pH changes within the ranges tested, probably because iron remained associated to the respective compounds.

Structure of Stenotrophomonas maltophilia FeoA complexed with zinc: a unique prokaryotic SH3-domain protein that possibly acts as a bacterial ferrous iron-transport activating factor

International Nuclear Information System (INIS)

Su, Yi-Che; Chin, Ko-Hsin; Hung, Hui-Chih; Shen, Gwan-Han; Wang, Andrew H.-J.; Chou, Shan-Ho

2010-01-01

The crystal structure of FeoA from Stenotrophomonas maltophilia has been determined to a resolution of 1.7 Å using an Se single-wavelength anomalous dispersion (Se-SAD) approach and revealed a unique dimer cross-linked by two zinc ions and six chloride ions. Iron is vital to the majority of prokaryotes, with ferrous iron believed to be the preferred form for iron uptake owing to its much better solubility. The major route for bacterial ferrous iron uptake is found to be via an Feo (ferrous iron-transport) system comprising the three proteins FeoA, FeoB and FeoC. Although the structure and function of FeoB have received much attention recently, the roles played by FeoA and FeoC have been little investigated to date. Here, the tertiary structure of FeoA from Stenotrophomonas maltophilia (Sm), a vital opportunistic pathogen in immunodepressed hosts, is reported. The crystal structure of SmFeoA has been determined to a resolution of 1.7 Å using an Se single-wavelength anomalous dispersion (Se-SAD) approach. Although SmFeoA bears low sequence identity to eukaryotic proteins, its structure is found to adopt a eukaryotic SH3-domain-like fold. It also bears weak similarity to the C-terminal SH3 domain of bacterial DtxR (diphtheria toxin regulator), with some unique characteristics. Intriguingly, SmFeoA is found to adopt a unique dimer cross-linked by two zinc ions and six anions (chloride ions). Since FeoB has been found to contain a G-protein-like domain with low GTPase activity, FeoA may interact with FeoB through the SH3–G-protein domain interaction to act as a ferrous iron-transport activating factor

Ferrous-activated persulfate oxidation of arsenic(III) and diuron in aquatic system.

Science.gov (United States)

Zhou, Lei; Zheng, Wei; Ji, Yuefei; Zhang, Jinfeng; Zeng, Chao; Zhang, Ya; Wang, Qi; Yang, Xi

2013-12-15

In situ chemical oxidation (ISCO) can be an effective technology for the remediation of soil and groundwater polluted by organic and inorganic contaminants. This study investigated the oxidation of arsenic(III) (As(III)) and diuron using ferrous activated persulfate-based ISCO. The results indicated that Fe(II)/persulfate oxidation could be an effective method to oxidize As(III) and diuron. Effects of pH, S2O8(2-) and Fe(II) amounts on the destruction of As(III) and diuron were examined in batch experiments. Acidic conditions favored the removal of As(III) and diuron. Four chelating agents, citric acid (CA), Na2S2O3, diethylene triamine pentaacetic acid (DTPA) and ethylene diamine tetraacetic acid disodium (EDTA-Na2) were used in attempt to maintain the quantity of ferrous ion in solution. In our experiments, CA and Na2S2O3 were found to be more effective than DTPA and EDTA-Na2. Our results also revealed a widely practical prospect of inorganic chelating agent Na2S2O3. Hydroxyl and sulfate radical were determined to play key roles in the oxidation process by using ethanol and tertiary butanol as molecular probes. Oxidation of As(III) yielded As(V) via the electron-transfer reaction. In the oxidation process of diuron, a stepwise nucleophilic substitution of chlorine by hydroxyl and a stepwise oxidation process of the methyl on the dimethylurea group by hydroxyl and sulfate radical were proposed. Copyright © 2013 Elsevier B.V. All rights reserved.

Higher Fe{sup 2+}/total Fe ratio in iron doped phosphate glass melted by microwave heating

Energy Technology Data Exchange (ETDEWEB)

Mandal, Ashis K., E-mail: ashis@cgcri.res.in [CSIR-Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata 700032 (India); Sinha, Prasanta K. [CSIR-Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata 700032 (India); Das, Dipankar [UGC-DAE Consortium for Scientific Research, Kolkata 700098 (India); Guha, Chandan [Department of Chemical Engineering, Jadavpur University, Kolkata 700032 (India); Sen, Ranjan [CSIR-Central Glass and Ceramic Research Institute, 196 Raja S.C. Mullick Road, Kolkata 700032 (India)

2015-03-15

Highlights: • Iron doped phosphate glasses prepared using microwave heating and conventional heating under air and reducing atmosphere. • Presence of iron predominantly in the ferrous oxidation state in all the glasses. • Significant concentrations of iron in the ferrous oxidation state on both octahedral and tetrahedral sites in all the glasses. • Ratio of Fe{sup 2+} with total iron is found higher in microwave prepared glasses in comparison to conventional prepared glasses. - Abstract: Iron doped phosphate glasses containing P{sub 2}O{sub 5}–MgO–ZnO–B{sub 2}O{sub 3}–Al{sub 2}O{sub 3} were melted using conventional resistance heating and microwave heating in air and under reducing atmosphere. All the glasses were characterised by UV–Vis–NIR spectroscopy, Mössbauer spectroscopy, thermogravimetric analysis and wet colorimetry analysis. Mössbauer spectroscopy revealed presence of iron predominantly in the ferrous oxidation state on two different sites in all the glasses. The intensity of the ferrous absorption peaks in UV–Vis–NIR spectrum was found to be more in glasses prepared using microwave radiation compared to the glasses prepared in a resistance heating furnace. Thermogravimetric analysis showed increasing weight gain on heating under oxygen atmosphere for glass corroborating higher ratio of FeO/(FeO + Fe{sub 2}O{sub 3}) in glass melted by direct microwave heating. Wet chemical analysis also substantiated the finding of higher ratio Fe{sup +2}/ΣFe in microwave melted glasses. It was found that iron redox ratio was highest in the glasses prepared in a microwave furnace under reducing atmosphere.

Phototrophs in high-iron-concentration microbial mats: physiological ecology of phototrophs in an iron-depositing hot spring

Science.gov (United States)

Pierson, B. K.; Parenteau, M. N.; Griffin, B. M.

1999-01-01

At Chocolate Pots Hot Springs in Yellowstone National Park the source waters have a pH near neutral, contain high concentrations of reduced iron, and lack sulfide. An iron formation that is associated with cyanobacterial mats is actively deposited. The uptake of [(14)C]bicarbonate was used to assess the impact of ferrous iron on photosynthesis in this environment. Photoautotrophy in some of the mats was stimulated by ferrous iron (1.0 mM). Microelectrodes were used to determine the impact of photosynthetic activity on the oxygen content and the pH in the mat and sediment microenvironments. Photosynthesis increased the oxygen concentration to 200% of air saturation levels in the top millimeter of the mats. The oxygen concentration decreased with depth and in the dark. Light-dependent increases in pH were observed. The penetration of light in the mats and in the sediments was determined. Visible radiation was rapidly attenuated in the top 2 mm of the iron-rich mats. Near-infrared radiation penetrated deeper. Iron was totally oxidized in the top few millimeters, but reduced iron was detected at greater depths. By increasing the pH and the oxygen concentration in the surface sediments, the cyanobacteria could potentially increase the rate of iron oxidation in situ. This high-iron-content hot spring provides a suitable model for studying the interactions of microbial photosynthesis and iron deposition and the role of photosynthesis in microbial iron cycling. This model may help clarify the potential role of photosynthesis in the deposition of Precambrian banded iron formations.

Ferrous-activated persulfate oxidation of arsenic(III) and diuron in aquatic system

International Nuclear Information System (INIS)

Zhou, Lei; Zheng, Wei; Ji, Yuefei; Zhang, Jinfeng; Zeng, Chao; Zhang, Ya; Wang, Qi; Yang, Xi

2013-01-01

Highlights: • Effective oxidation of As(III)/diuron is achieved by Fe(II)-activated persulfate. • Hydroxyl and sulfate radical play important roles in As(III) and diuron oxidation. • CA and Na 2 S 2 O 3 are efficient and environmental friendly chelating agents. • DFT calculation is found to be useful for degradation products prediction. -- Abstract: In situ chemical oxidation (ISCO) can be an effective technology for the remediation of soil and groundwater polluted by organic and inorganic contaminants. This study investigated the oxidation of arsenic(III) (As(III)) and diuron using ferrous activated persulfate-based ISCO. The results indicated that Fe(II)/persulfate oxidation could be an effective method to oxidize As(III) and diuron. Effects of pH, S 2 O 8 2− and Fe(II) amounts on the destruction of As(III) and diuron were examined in batch experiments. Acidic conditions favored the removal of As(III) and diuron. Four chelating agents, citric acid (CA), Na 2 S 2 O 3 , diethylene triamine pentaacetic acid (DTPA) and ethylene diamine tetraacetic acid disodium (EDTA-Na 2 ) were used in attempt to maintain the quantity of ferrous ion in solution. In our experiments, CA and Na 2 S 2 O 3 were found to be more effective than DTPA and EDTA-Na 2 . Our results also revealed a widely practical prospect of inorganic chelating agent Na 2 S 2 O 3 . Hydroxyl and sulfate radical were determined to play key roles in the oxidation process by using ethanol and tertiary butanol as molecular probes. Oxidation of As(III) yielded As(V) via the electron-transfer reaction. In the oxidation process of diuron, a stepwise nucleophilic substitution of chlorine by hydroxyl and a stepwise oxidation process of the methyl on the dimethylurea group by hydroxyl and sulfate radical were proposed

Consumption of galacto-oligosaccharides increases iron absorption from a micronutrient powder containing ferrous fumarate and sodium iron EDTA: a stable-isotope study in Kenyan infants.

Science.gov (United States)

Paganini, Daniela; Uyoga, Mary A; Cercamondi, Colin I; Moretti, Diego; Mwasi, Edith; Schwab, Clarissa; Bechtler, Salome; Mutuku, Francis M; Galetti, Valeria; Lacroix, Christophe; Karanja, Simon; Zimmermann, Michael B

2017-10-01

Background: Whether consumption of prebiotics increases iron absorption in infants is unclear. Objective: We set out to determine whether prebiotic consumption affects iron absorption from a micronutrient powder (MNP) containing a mixture of ferrous fumarate and sodium iron EDTA (FeFum+NaFeEDTA) in Kenyan infants. Design: Infants ( n = 50; aged 6-14 mo) consumed maize porridge that was fortified with an MNP containing FeFum+NaFeEDTA and 7.5 g galacto-oligosaccharides (GOSs) (Fe+GOS group, n = 22) or the same MNP without GOSs (Fe group, n = 28) each day for 3 wk. Then, on 2 consecutive days, we fed all infants isotopically labeled maize porridge and MNP test meals containing 5 mg Fe as 57 FeFum+Na 58 FeEDTA or ferrous sulfate ( 54 FeSO 4 ). Iron absorption was measured as the erythrocyte incorporation of stable isotopes. Iron markers, fecal pH, and bacterial groups were assessed at baseline and 3 wk. Comparisons within and between groups were done with the use of mixed-effects models. Results: There was a significant group-by-compound interaction on iron absorption ( P = 0.011). The median percentages of fractional iron absorption from FeFum+NaFeEDTA and from FeSO 4 in the Fe group were 11.6% (IQR: 6.9-19.9%) and 20.3% (IQR: 14.2-25.7%), respectively, ( P iron absorption was greater from the FeFum+NaFeEDTA ( P = 0.047) in the Fe+GOS group but not from the FeSO 4 ( P = 0.653). The relative iron bioavailability from FeFum+NaFeEDTA compared with FeSO 4 was higher in the Fe+GOS group than in the Fe group (88% compared with 63%; P = 0.006). There was a significant time-by-group interaction on Bifidobacterium spp. ( P = 0.008) and Lactobacillus / Pediococcus / Leuconostoc spp. ( P = 0.018); Lactobacillus / Pediococcus / Leuconostoc spp. decreased in the Fe group ( P = 0.013), and there was a nonsignificant trend toward higher Bifidobacterium spp. in the Fe+GOS group ( P = 0.099). At 3 wk, iron absorption was negatively correlated with fecal pH ( P iron absorption by 62

Surface oxidization-reduction reactions in Columbia Plateau basalts

International Nuclear Information System (INIS)

White, A.F.; Yee, A.

1984-01-01

Results are presented which define principal oxidation-reduction reactions expected between ground water and iron in the Umtanum and Cohassett basalt flows of south central Washington. Data include kinetics of aqueous iron speciation, rates of O 2 uptake and nature of oxyhydroxide precipitates. Such data are important in predicting behavior of radionuclides in basalt aquifers including determination of valence states, speciation, solubility, sorption, and coprecipitation on iron oxyhydroxide substrates and colloids. Analyses of the basalt by XPS indicates that ferrous iron is oxidized to ferric iron on the surface and that the total iron decreases as a function of pH during experimental weathering. Iron oxyhydroxide phases did not form surface coating on basalt surfaces but rather nucleated as separate plases in solution. No significant increases in Cs or Sr sorption were observed with increased weathering of the basalt. Concurrent increases in Fe(II) and decreases in Fe(III) in slightly to moderately acid solutions indicated continued oxidization of ferrous iron in the basalt. At neutral to basic pH, Fe(II) was strongly sorbed onto the basalt surface (Kd = 6.5 x 10 -3 1 x m 2 ) resulting in low dissolved concentrations even under anoxic conditions. The rate of O 2 uptake increased with decreasing pH. Diffusion rates (-- 10 -14 cm 2 x s -1 ), calculated using a one-dimensional analytical model, indicate grain boundary diffusion. Comparisons of Eh values calculated by Pt electrode, dissolved O 2 and Fe(II)/Fe(III) measurements showed considerable divergence, with the ferric-ferrous couple being the preferred method of estimating Eh

The Bradyrhizobium japonicum Ferrous Iron Transporter FeoAB Is Required for Ferric Iron Utilization in Free Living Aerobic Cells and for Symbiosis.

Science.gov (United States)

Sankari, Siva; O'Brian, Mark R

2016-07-22

The bacterium Bradyrhizobium japonicum USDA110 does not synthesize siderophores for iron utilization in aerobic environments, and the mechanism of iron uptake within symbiotic soybean root nodules is unknown. An mbfA bfr double mutant defective in iron export and storage activities cannot grow aerobically in very high iron medium. Here, we found that this phenotype was suppressed by loss of function mutations in the feoAB operon encoding ferrous (Fe(2+)) iron uptake proteins. Expression of the feoAB operon genes was elevated under iron limitation, but mutants defective in either gene were unable to grow aerobically over a wide external ferric (Fe(3+)) iron (FeCl3) concentration range. Thus, FeoAB accommodates iron acquisition under iron limited and iron replete conditions. Incorporation of radiolabel from either (55)Fe(2+) or (59)Fe(3+) into cells was severely defective in the feoA and feoB strains, suggesting Fe(3+) reduction to Fe(2+) prior to traversal across the cytoplasmic membrane by FeoAB. The feoA or feoB deletion strains elicited small, ineffective nodules on soybean roots, containing few bacteria and lacking nitrogen fixation activity. A feoA(E40K) mutant contained partial iron uptake activity in culture that supported normal growth and established an effective symbiosis. The feoA(E40K) strain had partial iron uptake activity in situ within nodules and in isolated cells, indicating that FeoAB is the iron transporter in symbiosis. We conclude that FeoAB supports iron acquisition under limited conditions of soil and in the iron-rich environment of a symbiotic nodule. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

21 CFR 186.1374 - Iron oxides.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Iron oxides. 186.1374 Section 186.1374 Food and... Substances Affirmed as GRAS § 186.1374 Iron oxides. (a) Iron oxides (oxides of iron, CAS Reg. No. 1332-37-2) are undefined mixtures of iron (II) oxide (CAS Reg. No. 1345-25-1, black cubic crystals) and iron (III...

Iron and steel industry and non-ferrous metal production - the electrical energy consumption and energy efficiency

International Nuclear Information System (INIS)

Blazhev, Blagoja; Sofeski, Slobodan

2002-01-01

Companies of iron and steel industry and non-ferrous metal production are the largest individual consumers of electricity and other forms of energy. This paper presents the electricity consumption in the last twenty-year period as well as data for their contribution in creating the gross domestic product (GDP) and engagement of labor force in the country. For some of the companies there is data for energy efficiency (kWh/t i.e. MJ/t) in last five years. (Original)

Iron and manganese in oxide minerals and in glasses: preliminary consideration of Eh buffering potential at Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Caporuscio, F.A.; Vaniman, D.T.

1985-04-01

The tuffs of Yucca Mountain at the Nevada Test Site are currently under investigation as a possible deep burial site for high-level radioactive waste disposal. One of the main concerns is the effect of oxidizing groundwater on the transport of radionuclides. Rock components that may affect the oxygen content of groundwater include Fe-Ti oxides, Mn oxides, and glasses that contain ferrous iron. Some phenocryst Fe-Ti oxides at Yucca Mountain are in reduced states, whereas groundmass Fe-Ti oxides have been oxidized to hematite, rutile, and pseudobrookite (Fe 3+ -bearing phases) exclusively. Estimates of Fe 2+ -bearing oxides indicate that less than 0.33 vol% phenocrysts is available to act as solid buffering agents of Eh. Of this percentage, significant amounts of Fe-Ti oxides are isolated from effective interaction with groundwater because they occur in densely welded, devitrified tuffs that have low interstitial permeability. Manganese oxides occur primarily along fractures in the ash-flow tuffs. Because the Mn oxides are concentrated along the same pathways (fractures) where transport has occurred in the past, these small volume percentages could act as buffers. However, the oxidation states of actual Mn-oxide phases are high (Mn 4+ ), and these minerals have virtually no potential for reducing groundwater Eh. Manganese oxides may even act as oxidizing agents. However, regardless of their poor capabilities as reducing agents, the Mn oxides could be important as sorbents of heavy metals at Yucca Mountain. The lack of accessible, pristine Fe-Ti oxides and the generally high oxidation states of Mn oxides seem to rule out these oxides as Eh buffers of the Yucca Mountain groundwater system. Reduction of ferrous iron within glassy tuffs may have some effect on Eh, but further study is needed. At present it is prudent to assume that minerals and glasses have little or no capacity for reducing oxygen-rich groundwater at Yucca Mountain. 25 refs., 3 figs., 12 tabs

A novel reverse osmosis membrane by ferrous sulfate assisted controlled oxidation of polyamide layer

Science.gov (United States)

Raval, Hiren D.; Raviya, Mayur R.; Gauswami, Maulik V.

2017-11-01

With growing desalination capacity, it is very important to evaluate the performance of thin film composite reverse osmosis (TFC RO) membrane in terms of energy consumption for desalination. There is a trade-off between salt rejection and water-flux of TFC RO membrane. This article presents a novel approach of analyzing the effect of mixture of an oxidizing agent sodium hypochlorite and a reducing agent ferrous sulfate on virgin TFC RO membrane. Experiments were carried out by varying the concentrations of both sodium hypochlorite and ferrous sulfate. The negative charge was induced on the membrane due to the treatment of combination of sodium hypochlorite and ferrous sulfate, thereby resulting in higher rejection of negative ions due to repulsive force. Membrane treated with 1000 mg l-1 sodium hypochlorite and 2000 mg l-1 ferrous sulfate showed the best salt rejection i.e. 96.23%. The characterization was carried out to understand the charge on the membrane surface by Zeta potential, morphology of membrane surface by scanning electron microscope (SEM), surface roughness features by atomic force microscope (AFM) and chemical structural changes by nuclear magnetic resonance (NMR) analysis.

The Use of Flow-Injection Analysis with Chemiluminescence Detection of Aqueous Ferrous Iron in Waters Containing High Concentrations of Organic Compounds

Directory of Open Access Journals (Sweden)

Carrick M. Eggleston

2009-06-01

Full Text Available An evaluation of flow-injection analysis with chemiluminescence detection (FIA-CL to quantify Fe2+(aq in freshwaters was performed. Iron-coordinating and/or iron-reducing compounds, dissolved organic matter (DOM, and samples from two natural water systems were used to amend standard solutions of Fe2+(aq. Slopes of the response curves from ferrous iron standards (1 – 100 nM were compared to the response curves of iron standards containing the amendments. Results suggest that FIA-CL is not suitable for systems containing ascorbate, hydroxylamine, cysteine or DOM. Little or no change in sensitivity occurred in solutions of oxalate and glycine or in natural waters with little organic matter.

Characterization and uranium bioleaching performance of mixed iron- and sulfur-oxidizers versus iron-oxidizers

International Nuclear Information System (INIS)

Qian Li; Jing Sun; Dexin Ding; Qingliang Wang; Wenge Shi; Eming Hu; Xiaoyu Jiang; University of South China, Hengyang; Xingxing Wang

2017-01-01

In order to develop and apply mixed iron- and sulfur-oxidizers in uranium bioleaching, the characteristics of a mixed iron- and sulfur-oxidizing consortium (Consortium ISO) were comparatively investigated versus an iron-oxidizing consortium (Consortium IO). The results showed, the Consortium ISO exerted stronger oxidative ability and acid-producing ability than Consortium IO did. The synergy of sulfur-oxidizers and iron-oxidizers could change the structure and properties of the passivation substance, and work positively for eliminating the accumulation of passivation substance. In the bioleaching process, the uranium bioleaching experiments showed the recovery percentage of uranium reached 99.5% with Consortium ISO, 6.3% more than that of Consortium IO. (author)

Report on assessment of the mechanism of bacterially assisted oxidation of pyritic uranium tailings

International Nuclear Information System (INIS)

Halbert, B.B.; Scharer, J.M.; Knapp, R.A.

1984-07-01

The oxidation of pyritic minerals has been shown to be catalyzed by the presence of iron- and sulphur-oxidizing bacteria. Thiobacillus ferroxidans plays the most significant role in the formation and propagation of acidic conditions. Optimum growth conditions for the T. ferroxidans occurs at a temperature of 35 degrees C and pH of 2 to 3. Bacterially assisted oxidation of pyrite involves both direct and indirect contact mechanisms. The direct contact mechanism entails enzymatic oxidation of the insoluble sulphide moiety. The indirect mechanism involves bacterial oxidation of the dissolved ferrous component to the ferric state. The ferric iron, in turn, acts as the prime oxidant of pyrite and is reduced to ferrous iron. The re-oxidation of the dissolved ferrous component which is catalyzed by bacterial activity, completes the cyclic process. The rate of bacterial oxidation is affected by: the geochemistry and reactivity of the pyritic material; the amount of pyrite present in the waste material and the exposed surface area of the pyritic component; the availability of oxygen and carbon dioxide; the pH and temperature of the leach solution; and the presence (or absence) of organic inhibitors. Of the above factors, oxygen has been frequently identified as the rate limiting reactant in tailings

Mechanisms of an increased level of serum iron in gamma-irradiated mice

International Nuclear Information System (INIS)

Xie, Li-hua; Zhang, Xiao-hong; Hu, Xiao-dan; Min, Xuan-yu; Zhou, Qi-fu; Zhang, Hai-qian

2016-01-01

The potential mechanisms underlying the increase in serum iron concentration in gamma-irradiated mice were studied. The gamma irradiation dose used was 4 Gy, and cobalt-60 ( 60 Co) source was used for the irradiation. The dose rate was 0.25 Gy/min. In the serum of irradiated mice, the concentration of ferrous ions decreased, whereas the serum iron concentration increased. The concentration of ferrous ions in irradiated mice returned to normal at 21 day post-exposure. The concentration of reactive oxygen species in irradiated mice increased immediately following irradiation but returned to normal at 7 day post-exposure. Serum iron concentration in gamma-irradiated mice that were pretreated with reduced glutathione was significant lower (p < 0.01) than that in mice exposed to gamma radiation only. However, the serum iron concentration was still higher than that in normal mice (p < 0.01). This change was biphasic, characterized by a maximal decrease phase occurring immediately after gamma irradiation (relative to the irradiated mice) and a recovery plateau observed during the 7th and 21st day post-irradiation, but serum iron recovery was still less than that in the gamma-irradiated mice (4 Gy). In gamma-irradiated mice, ceruloplasmin activity increased and serum copper concentration decreased immediately after irradiation, and both of them were constant during the 7th and 21st day post-irradiation. It was concluded that ferrous ions in irradiated mice were oxidized to ferric ions by ionizing radiation. Free radicals induced by gamma radiation and ceruloplasmin mutually participated in this oxidation process. The ferroxidase effect of ceruloplasmin was achieved by transfer of electrons from ferrous ions to cupric ions. (orig.)

Solubility Model for Ferrous Iron Hydroxide, Hibbingite, Siderite, and Chukanovite in High Saline Solutions of Sodium Chloride, Sodium Sulfate, and Sodium Carbonate

International Nuclear Information System (INIS)

Kim, Sungtae; Marrs, Cassandra; Nemer, Martin; Jang, Jay Je-Hun

2017-01-01

Here, a solubility model is presented for ferrous iron hydroxide (Fe(OH) 2 (s)), hibbingite (Fe 2 Cl(OH) 3 (s)), siderite (FeCO 3 (s)), and chukanovite (Fe 2 CO 3 (OH) 2 (s)). The Pitzer activity coefficient equation was utilized in developing the model to account for the excess free energies of aqueous species in the background solutions of high ionic strength. Solubility limiting minerals were analyzed before and after experiments using X-ray diffraction. Formation of Fe(OH) 2 (s) was observed in the experiments that were initiated with Fe 2 Cl(OH) 3 (s) in Na 2 SO 4 solution. Coexistence of siderite and chukanovite was observed in the experiments in Na 2 CO 3 + NaCl solutions. Two equilibrium constants that had been reported by us for the dissolution of Fe(OH) 2 (s) and Fe 2 Cl(OH) 3 (s) (Nemer et al.) were rederived in this paper, using newer thermodynamic data selected from the literature to maintain internal consistency of the series of our data analyses in preparation, including this paper. Three additional equilibrium constants for the following reactions were determined in this paper: dissolution of siderite and chukanovite and dissociation of the aqueous species Fe(CO 3 ) 2 –2 . Five Pitzer interaction parameters were derived in this paper: β (0) , β (1) , and C φ parameters for the species pair Fe +2 /SO 4 –2 ; β (0) and β (1) parameters for the species pair Na+/Fe(CO3)2–2. Our model predicts that, among the four inorganic ferrous iron minerals, siderite is the stable mineral in two WIPP-related brines (WIPP: Waste Isolation Pilot Plant), i.e., GWB and ERDA6 (Brush and Domski), and the electrochemical equilibrium between elemental iron and siderite provides a low oxygen fugacity (10 –91.2 atm) that can keep the actinides at their lowest oxidation states. (Nemer et al., Brush and Domski; references numbered 1 and 2 in the main text).

Ferrous-activated persulfate oxidation of arsenic(III) and diuron in aquatic system

Energy Technology Data Exchange (ETDEWEB)

Zhou, Lei [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Zheng, Wei [Jiangsu Product Quality Supervision and Inspection Research Institute, Nanjing 210007 (China); Ji, Yuefei [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Université Lyon 1, UMR CNRS 5256, Institut de recherches sur la catalyse et l’environnement de Lyon (IRCELYON), 2 Avenue Albert Einstein, F-69626 Villeurbanne (France); Zhang, Jinfeng; Zeng, Chao; Zhang, Ya; Wang, Qi [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Yang, Xi, E-mail: yangxi@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China)

2013-12-15

Highlights: • Effective oxidation of As(III)/diuron is achieved by Fe(II)-activated persulfate. • Hydroxyl and sulfate radical play important roles in As(III) and diuron oxidation. • CA and Na{sub 2}S{sub 2}O{sub 3} are efficient and environmental friendly chelating agents. • DFT calculation is found to be useful for degradation products prediction. -- Abstract: In situ chemical oxidation (ISCO) can be an effective technology for the remediation of soil and groundwater polluted by organic and inorganic contaminants. This study investigated the oxidation of arsenic(III) (As(III)) and diuron using ferrous activated persulfate-based ISCO. The results indicated that Fe(II)/persulfate oxidation could be an effective method to oxidize As(III) and diuron. Effects of pH, S{sub 2}O{sub 8}{sup 2−} and Fe(II) amounts on the destruction of As(III) and diuron were examined in batch experiments. Acidic conditions favored the removal of As(III) and diuron. Four chelating agents, citric acid (CA), Na{sub 2}S{sub 2}O{sub 3}, diethylene triamine pentaacetic acid (DTPA) and ethylene diamine tetraacetic acid disodium (EDTA-Na{sub 2}) were used in attempt to maintain the quantity of ferrous ion in solution. In our experiments, CA and Na{sub 2}S{sub 2}O{sub 3} were found to be more effective than DTPA and EDTA-Na{sub 2}. Our results also revealed a widely practical prospect of inorganic chelating agent Na{sub 2}S{sub 2}O{sub 3}. Hydroxyl and sulfate radical were determined to play key roles in the oxidation process by using ethanol and tertiary butanol as molecular probes. Oxidation of As(III) yielded As(V) via the electron-transfer reaction. In the oxidation process of diuron, a stepwise nucleophilic substitution of chlorine by hydroxyl and a stepwise oxidation process of the methyl on the dimethylurea group by hydroxyl and sulfate radical were proposed.

Thermodynamic data for iron (II) in high-saline solutions at temperatures up to 90 C

Energy Technology Data Exchange (ETDEWEB)

Munoz, Andres G.; Scharge, Tina; Moog, Helge C.

2013-12-15

For natural aqueous systems in general and for the near field of underground nuclear waste repositories in particular thermodynamic properties of iron species and solid phases are of predominant importance. Regardless of the question of the host rock, nuclear waste containment in Germany will be based on massive steel canisters. The total mass of iron present in a repository can be, dependent on the applied variant, sum up to more than 100 000 tons. The overall geochemical milieu including pH and EH will be dominated by the overall abundance of metallic, ferrous, and ferric iron, their aqueous speciation and solid iron-phases. This milieu is imposed on all other equilibria of interest, including those which determine radionuclide solubility. In addition to this, iron bearing corrosion phases due to their shear mass may exhibit a significant sink for radionuclides in terms of incorporation or sorption. As to the evolution of EH it is important to note that application of the Nernst equation requires knowing the electrochemical activities of the involved reactants. Iron is present in aqueous solutions in two oxidation states: +II (ferrous iron) and +III (ferric iron). Ferric iron exhibits a much more complex speciation behavior than ferrous iron, where from a conceptual point of view many species may be neglected. Ferric iron, on the contrary, is subject to considerable complex formation with chloride, sulfate, and - most importantly - with hydroxide. For this reason, experimental and theoretical treatment of ''iron'' at GRS in high saline solutions proceeded along two strings, one for each oxidation state, with the ultimate goal to deliver a thermodynamic model for ''iron'' in high saline solutions.

Iron precipitations in the Lusatian lignite district. Pt. 1: water pumpage and water drainage in the opencast mine of Nochten, hydrochemistry of mine water; Eisenausfaellungen im Lausitzer Braunkohlerevier. T. 1: Wasserhebung und -ableitung im Tagebau Nochten, Hydrochemie der Suempfungswaesser

Energy Technology Data Exchange (ETDEWEB)

Arnold, I. [LAUBAG, Senftenberg (Germany); Uhlmann, W. [IWB - Institut fuer Wasser und Boden, Dresden (Germany)

2002-09-01

Opencast lignite mines are subject to permanent drainage. Due to iron disulphide weathering, drainage waters are acidic and rich in ferrous iron and sulphate. In the case of the mine Nochten (Lusatia, East Germany) the originating water is directed from the mine through several open ditches and finally through a pipeline to reach to purification plant at a distance of 14 km. During this course part of the ferrous iron is oxidised to form ferric iron, which precipitates as Fe(III)-minerals. The iron loss in the drainage system between the open cast Nochten to the purification plant Schwarze Pumpe is 30-37% under summer conditions and 18% under winter conditions. Especially for the pipeline these precipitates represent a serious problem, as they result in incrustations and therefore in decreased discharge rates. This article focuses on the hydrochemical processes occurring during the discharge of water to the purification plant. Investigations were based on hydrochemical measurements in the drainage systems as well as on laboratory experiments on the oxidation kinetics of ferrous iron. These resulted in the following findings: (1) The oxidation of ferrous iron in the acidic waters is slow even at oxygen concentrations near saturation. Thus, oxygen is not the limiting factor for the oxidation process. (2) Oxidation kinetics are strongly dependent on temperature. Conclusively, a reduction of iron precipitates may be achieved firstly by shortening the distance of the transport course and secondly by preventing a warming up of waters in summer. (orig.)

Investigation of iron-containing complexes of deoxyribonucleic acid nucleosides by Moessbauer spectroscopy

International Nuclear Information System (INIS)

Greguskova, M.; Novotny, J.; Cernohorsky, I.; Cirak, J.

1975-01-01

DNA and nucleoside complexes with ferric and ferrous ions were investigated for the concentration of iron ions, ionic strength, temperature, and the nature and spatial configuration of neighbouring atoms of the iron ions in the complexes. Moessbauer spectroscopy was used. The Moessbauer measurements were conducted on lyophilized samples at room temperature (300 K) and on frozen solutions at liquid nitrogen temperature (77 K). Quadrupole splitting was found in all spectra obtained by a Pd(Co) source, with the exception of thymidine, thus indicating that the formation of complexes had not affected the oxidation state of iron ions. A decrease in isomer shift and an increase in quadrupole splitting were found in all spectra obtained by an iron(III) chloride source as well as in all spectra obtained by an iron chloride tetrahydrate source. UV irradiation of the samples prior to the Moessbauer measurements was found to have no effect on the Moessbauer spectra but to result in changes in the oxidation state of iron ions, mainly their valency and the ferrous/ferric ion ratio. The results are shown in a table and in graphs. (L.O.)

Oxidation of Dodecanoate Intercalated Iron(II)–Iron(III) Layered Double Hydroxide to Form 2D Iron(III) (Hydr)oxide Layers

DEFF Research Database (Denmark)

Huang, Li‐Zhi; Ayala‐Luis, Karina B.; Fang, Liping

2013-01-01

hydroxide planar layer were preserved during the oxidation, as shown by FTIR spectroscopy. The high positive charge in the hydroxide layer produced by the oxidation of iron(II) to iron(III) is partially compensated by the deprotonation of hydroxy groups, as shown by X‐ray photoelectron spectroscopy...... between the alkyl chains of the intercalated dodecanoate anions play a crucial role in stabilizing the structure and hindering the collapse of the iron(II)–iron(III) (hydr)oxide structure during oxidation. This is the first report describing the formation of a stable planar layered octahedral iron......(III) (hydr)oxide. oxGRC12 shows promise as a sorbent and host for hydrophobic reagents, and as a possible source of single planar layers of iron(III) (hydr)oxide....

Immobilization of Acidithiobacillus ferrooxidans on sulfonated microporous poly(styrene-divinylbenzene) copolymer with granulated activated carbon and its use in bio-oxidation of ferrous iron.

Science.gov (United States)

Koseoglu-Imer, Derya Yuksel; Keskinler, Bulent

2013-01-01

The immobilization efficiencies of Acidithiobacillus ferrooxidans cells on different immobilization matrices were investigated for biooxidation of ferrous iron (Fe(2+)) to ferric iron (Fe(3+)). Six different matrices were used such as the polyurethane foam (PUF), granular activated carbon (GAC), raw poly(styrene-divinylbenzene) copolymer (rawSDVB), raw poly(styrene-divinylbenzene) copolymer with granular activated carbon (rawSDVB-GAC), sulfonated poly(styrene-divinylbenzene) copolymer (sulfSDVB) and sulfonated poly(styrene-divinylbenzene) copolymer with granular activated carbon (sulfSDVB-GAC). The sulfSDVB-GAC polymer showed the best performance for Fe(2+) biooxidation. It was used at packed-bed bioreactor and the kinetic parameters were obtained. The highest Fe(2+) biooxidation rate (R) was found to be 4.02 g/L h at the true dilution rate (Dt) of 2.47 1/h and hydraulic retention time (τ) of 0.4 h. The sulfSDVB-GAC polymer was used for the first time as immobilization material for A. ferrooxidans for Fe(2+) biooxidation. Copyright © 2012 Elsevier B.V. All rights reserved.

21 CFR 73.2250 - Iron oxides.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Iron oxides. 73.2250 Section 73.2250 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2250 Iron oxides. (a) Identity. The color additives iron oxides consist of any one or any combination of synthetically prepared iron oxides, including the...

Sugars increase non-heme iron bioavailability in human epithelial intestinal and liver cells.

Directory of Open Access Journals (Sweden)

Tatiana Christides

Full Text Available Previous studies have suggested that sugars enhance iron bioavailability, possibly through either chelation or altering the oxidation state of the metal, however, results have been inconclusive. Sugar intake in the last 20 years has increased dramatically, and iron status disorders are significant public health problems worldwide; therefore understanding the nutritional implications of iron-sugar interactions is particularly relevant. In this study we measured the effects of sugars on non-heme iron bioavailability in human intestinal Caco-2 cells and HepG2 hepatoma cells using ferritin formation as a surrogate marker for iron uptake. The effect of sugars on iron oxidation state was examined by measuring ferrous iron formation in different sugar-iron solutions with a ferrozine-based assay. Fructose significantly increased iron-induced ferritin formation in both Caco-2 and HepG2 cells. In addition, high-fructose corn syrup (HFCS-55 increased Caco-2 cell iron-induced ferritin; these effects were negated by the addition of either tannic acid or phytic acid. Fructose combined with FeCl3 increased ferrozine-chelatable ferrous iron levels by approximately 300%. In conclusion, fructose increases iron bioavailability in human intestinal Caco-2 and HepG2 cells. Given the large amount of simple and rapidly digestible sugars in the modern diet their effects on iron bioavailability may have important patho-physiological consequences. Further studies are warranted to characterize these interactions.

CD/MCD/VTVH-MCD Studies of Escherichia coli Bacterioferritin Support a Binuclear Iron Cofactor Site.

Science.gov (United States)

Kwak, Yeonju; Schwartz, Jennifer K; Huang, Victor W; Boice, Emily; Kurtz, Donald M; Solomon, Edward I

2015-12-01

Ferritins and bacterioferritins (Bfrs) utilize a binuclear non-heme iron binding site to catalyze oxidation of Fe(II), leading to formation of an iron mineral core within a protein shell. Unlike ferritins, in which the diiron site binds Fe(II) as a substrate, which then autoxidizes and migrates to the mineral core, the diiron site in Bfr has a 2-His/4-carboxylate ligand set that is commonly found in diiron cofactor enzymes. Bfrs could, therefore, utilize the diiron site as a cofactor rather than for substrate iron binding. In this study, we applied circular dichroism (CD), magnetic CD (MCD), and variable-temperature, variable-field MCD (VTVH-MCD) spectroscopies to define the geometric and electronic structures of the biferrous active site in Escherichia coli Bfr. For these studies, we used an engineered M52L variant, which is known to eliminate binding of a heme cofactor but to have very minor effects on either iron oxidation or mineral core formation. We also examined an H46A/D50A/M52L Bfr variant, which additionally disrupts a previously observed mononuclear non-heme iron binding site inside the protein shell. The spectral analyses define a binuclear and an additional mononuclear ferrous site. The biferrous site shows two different five-coordinate centers. After O2 oxidation and re-reduction, only the mononuclear ferrous signal is eliminated. The retention of the biferrous but not the mononuclear ferrous site upon O2 cycling supports a mechanism in which the binuclear site acts as a cofactor for the O2 reaction, while the mononuclear site binds the substrate Fe(II) that, after its oxidation to Fe(III), migrates to the mineral core.

Synthesis and analysis of some iron vitamins

International Nuclear Information System (INIS)

Nimir, H.; Salah Eldin, E.; Mohammed, K.

2009-01-01

Ferrous sulfate tablets and syrup were prepared according to the pharmaceutical methods. Two types of biologically related iron salts, namely ferrous citrate and glycinate were prepared as potential iron supplements. The quantitative analysis of iron in these samples was determined using two techniques, atomic absorption spectrophotometery and uv-visible spectroscopy. The amount of iron was found to be 0.52-0.60 mg in tablet and 0.805-0.840g/100 ml in the syrup respectively. The percentage of Fe in the two ferrous citrate samples and ferrous glycinate sample were found to be 88.65%, 26.22% and 60.63% respectively. (Author)

Microbial reduction of iron ore

Science.gov (United States)

Hoffmann, M.R.; Arnold, R.G.; Stephanopoulos, G.

1989-11-14

A process is provided for reducing iron ore by treatment with microorganisms which comprises forming an aqueous mixture of iron ore, microorganisms operable for reducing the ferric iron of the iron ore to ferrous iron, and a substrate operable as an energy source for the microbial reduction; and maintaining the aqueous mixture for a period of time and under conditions operable to effect the reduction of the ore. Preferably the microorganism is Pseudomonas sp. 200 and the reduction conducted anaerobically with a domestic wastewater as the substrate. An aqueous solution containing soluble ferrous iron can be separated from the reacted mixture, treated with a base to precipitate ferrous hydroxide which can then be recovered as a concentrated slurry. 11 figs.

Effect of three Electron Shuttles on Bioreduction of Ferric Iron in two Acidic and Calcareous soils

Directory of Open Access Journals (Sweden)

Setareh Sharifi

2017-01-01

Full Text Available Introduction: Iron cycle is one of the most important biogeochemical processes which affect the availability of iron in soils. Ferric iron oxides are the most abundant forms of iron in soils and sediments. Ferric iron is highly insoluble at circumneutral pH. Present investigations have shown that the structural ferric iron bound in clay minerals is reduced by some microorganisms. Anaerobic bacteria reduce ferric iron which bound to soil clay minerals under anaerobic conditions. They have the ability to use ferric iron as a terminal electron acceptor. Many studies presented that dissimilatory iron reducing bacteria (DIRB mediate the transfer of electrons from small organic molecules like acetate and glucose to various humic materials (electron shuttles which then pass electrons abiotically to ferric iron oxyhydroxide and phyllosilicate minerals. Electron shuttles like AQDS, a tricyclic quinone, increase the rate of iron reduction by iron reducing bacteria on sites of iron oxides and oxyhydroxides. By increasing the rate of bioreduction of ferric iron, the solubility and availability of iron enhanced meaningfully. Royer et al. (2002 showed that bioreduction of hematite (common iron mineral in soils increased more than three times in the presence of AQDS and Shewanella putrefaciens comparedto control treatments. Previous works have mostly used synthetic minerals as electron acceptor in bioreduction process. Furthermore, the effect of quinones as electron acceptor for microorganisms were studied with poorly crystalline ferric iron oxides . The main objective of this study was to study the effect of AQS, humic acid and fulvic acid (as electron shuttle and Shewanella sp. and Pseudomonas aeruginosa, on bioreduction of native ferric iron in two acidic and calcareous soils. Materials and Methods: An experiment was conducted in a completely randomized design with factorial arrangement and three replications in vitro condition. The soil samples collected

Reduction enhances yields of nitric oxide trapping by iron-diethyldithiocarbamate complex in biological systems.

NARCIS (Netherlands)

Vanin, A.F.; Bevers, L.M.; Mikoyan, V.D.; Poltorakov, A.P.; Kubrina, L.N.; Faassen, E. van

2007-01-01

The mechanism of NO trapping by iron-diethylthiocarbamate complexes was investigated in cultured cells and animal and plant tissues. Contrary to common belief, the NO radicals are trapped by iron-diethylthiocarbamates not only in ferrous but in ferric state also in the biosystems. When DETC was

Facile and sustainable synthesis of shaped iron oxide nanoparticles: effect of iron precursor salts on the shapes of iron oxides.

Science.gov (United States)

Sayed, Farheen N; Polshettiwar, Vivek

2015-05-05

A facile and sustainable protocol for synthesis of six different shaped iron oxides is developed. Notably, all the six shapes of iron oxides can be synthesised using exactly same synthetic protocol, by simply changing the precursor iron salts. Several of the synthesised shapes are not reported before. This novel protocol is relatively easy to implement and could contribute to overcome the challenge of obtaining various shaped iron oxides in economical and sustainable manner.

Evaluation of effects of Maṇḍurabhasma on structural and functional integrity of small intestine in comparison with ferrous sulfate using an experimental model of iron deficiency anemia

Directory of Open Access Journals (Sweden)

Suchita Rajanikant Gawde

2015-01-01

Conclusion: Rats receiving a high dose of MB have shown improvement in hematinic and lactase levels comparable to those receiving ferrous sulfate. However, it causes lesser oxidative damage as compared to ferrous sulfate. This is an encouraging finding because it indicates the potential of MB to cause lesser gastrointestinal side effects compared to ferrous sulfate.

Reduction of ferric iron by acidophilic heterotrophic bacteria: evidence for constitutive and inducible enzyme systems in Acidiphilium spp.

Science.gov (United States)

Johnson, D B; Bridge, T A M

2002-01-01

To compare the abilities of two obligately acidophilic heterotrophic bacteria, Acidiphilium acidophilum and Acidiphilium SJH, to reduce ferric iron to ferrous when grown under different culture conditions. Bacteria were grown in batch culture, under different aeration status, and in the presence of either ferrous or ferric iron. The specific rates of ferric iron reduction by fermenter-grown Acidiphilium SJH were unaffected by dissolved oxygen (DO) concentrations, while iron reduction by A. acidophilum was highly dependent on DO concentrations in the growth media. The ionic form of iron present (ferrous or ferric) had a minimal effect on the abilities of harvested cells to reduce ferric iron. Whole cell protein profiles of Acidiphilium SJH were very similar, regardless of the DO status of the growth medium, while additional proteins were present in A. acidophilum grown microaerobically compared with aerobically-grown cells. The dissimilatory reduction of ferric iron is constitutive in Acidiphilium SJH while it is inducible in A. acidophilum. Ferric iron reduction by Acidiphilium spp. may occur in oxygen-containing as well as anoxic acidic environments. This will detract from the effectiveness of bioremediation systems where removal of iron from polluted waters is mediated via oxidation and precipitation of the metal.

Influence of iron on plutonium absorption by the adult and neonatal rat

International Nuclear Information System (INIS)

Sullivan, M.F.; Ruemmler, P.S.; Buschbom, R.L.

1986-01-01

To determine how iron affects plutonium absorption, adult rats were gavaged with 238 Pu nitrate (pH 2) after they had been fed an iron-deficient diet or treated with iron supplements. Neonatal rats born to dams on an iron-deficient diet were also gavaged with 238 Pu. An iron-deficient diet resulted in enhanced 238 Pu absorption both in the adults and in neonates born to iron-deficient dams. Ferric iron increased 238 Pu absorption 12-fold in adult rats; injected iron-dextran reduced that increase; gavaged ferrous iron reduced 238 Pu absorption to one-third of the control value. Rat neonates absorbed 30 to 40 times as much 238 Pu as adults; absorption was lowered in groups that received iron supplements: Iron-dextran caused a 50% reduction; ferric iron, 95%; and ferrous iron, greater than 95%. The results demonstrate an effect of the oxidation state of iron on plutonium absorption in adult rats different from that observed in suckling rats. The results suggest that the high rate of 238 Pu absorption by neonatal animals is due not only to the permeability of their intestines but also to their high demand for iron

Superparamagnetic iron oxides for MRI

International Nuclear Information System (INIS)

Weissleder, R.; Reimer, P.

1993-01-01

Pharmaceutical iron oxide preparations have been used as MRI contrast agents for a variety of purposes. These agents predominantly decrease T2 relaxation times and therefore cause a decrease in signal intensity of tissues that contain the agent. After intravenous administration, dextran-coated iron oxides typically accumulate in phagocytic cells in liver and spleen. Clinical trials have shown that iron oxide increases lesion/liver and lesion/spleen contrast, that more lesions can be depicted than on plain MRI or CT, and that the size threshold for lesion detection decreases. Decreased uptake of iron oxides in liver has been observed in hepatitis and cirrhosis, potentially allowing the assessment of organ function. More recently a variety of novel, target-specific monocrystalline iron oxides compounds have been used for receptor and immunospecific images. Future development of targeted MRI contrast agents is critical for organ- or tissue-specific quantitative and functional MRI. (orig.)

Superparamagnetic iron oxides for MRI

Energy Technology Data Exchange (ETDEWEB)

Weissleder, R [MGH-NMR Center, Dept. of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Reimer, P [MGH-NMR Center, Dept. of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); [Inst. fuer Klinische Radiologie, Zentrale Roentgendiagnostik, Westfaelische-Wilhelms-Univ., Muenster (Germany)

1993-06-01

Pharmaceutical iron oxide preparations have been used as MRI contrast agents for a variety of purposes. These agents predominantly decrease T2 relaxation times and therefore cause a decrease in signal intensity of tissues that contain the agent. After intravenous administration, dextran-coated iron oxides typically accumulate in phagocytic cells in liver and spleen. Clinical trials have shown that iron oxide increases lesion/liver and lesion/spleen contrast, that more lesions can be depicted than on plain MRI or CT, and that the size threshold for lesion detection decreases. Decreased uptake of iron oxides in liver has been observed in hepatitis and cirrhosis, potentially allowing the assessment of organ function. More recently a variety of novel, target-specific monocrystalline iron oxides compounds have been used for receptor and immunospecific images. Future development of targeted MRI contrast agents is critical for organ- or tissue-specific quantitative and functional MRI. (orig.)

Nanocompounds of iron and zinc: their potential in nutrition

NARCIS (Netherlands)

Zimmermann, M.B.; Hilty, F.M.

2011-01-01

Recent studies suggest nanostructured oxides and phosphates of Fe and atomically mixed Fe/Zn may be useful for nutritional applications. These compounds may have several advantages over existing fortificants, such as ferrous sulfate (FeSO(4)), NaFeEDTA and electrolytic iron. Because of their very

Hydroxylamine-induced oxidation of ferrous carbonylated truncated hemoglobins from Mycobacterium tuberculosis and Campylobacter jejuni is limited by carbon monoxide dissociation.

Science.gov (United States)

Ascenzi, Paolo; Ciaccio, Chiara; Gasperi, Tecla; Pesce, Alessandra; Caporaso, Lucia; Coletta, Massimo

2017-08-01

Hydroxylamine (HA) is an oxidant of ferrous globins and its action has been reported to be inhibited by CO, even though this mechanism has not been clarified. Here, kinetics of the HA-mediated oxidation of ferrous carbonylated Mycobacterium tuberculosis truncated hemoglobin N and O (Mt-trHbN(II)-CO and Mt-trHbO(II)-CO, respectively) and Campylobacter jejuni truncated hemoglobin P (Cj-trHbP(II)-CO), at pH 7.2 and 20.0 °C, are reported. Mixing Mt-trHbN(II)-CO, Mt-trHbO(II)-CO, and Cj-trHbP(II)-CO solution with the HA solution brings about absorption spectral changes reflecting the disappearance of the ferrous carbonylated derivatives with the concomitant formation of the ferric species. HA oxidizes irreversibly Mt-trHbN(II)-CO, Mt-trHbO(II)-CO, and Cj-trHbP(II)-CO with the 1:2 stoichiometry. The dissociation of CO turns out to be the rate-limiting step for the oxidation of Mt-trHbN(II)-CO, Mt-trHbO(II)-CO, and Cj-trHbP(II)-CO by HA. Values of the second-order rate constant for HA-mediated oxidation of Mt-trHbN(II)-CO, Mt-trHbO(II)-CO, and Cj-trHbP(II)-CO range between 8.8 × 10 4 and 8.6 × 10 7 M -1 s -1 , reflecting different structural features of the heme distal pocket. This study (1) demonstrates that the inhibitory effect of CO is linked to the dissociation of this ligand, giving a functional basis to previous studies, (2) represents the first comparative investigation of the oxidation of ferrous carbonylated bacterial 2/2 globins belonging to the N, O, and P groups by HA, (3) casts light on the correlation between kinetics of HA-mediated oxidation and carbonylation of globins, and (4) focuses on structural determinants modulating the HA-induced oxidation process.

O2-mediated oxidation of ferrous nitrosylated human serum heme-albumin is limited by nitrogen monoxide dissociation

International Nuclear Information System (INIS)

Ascenzi, Paolo; Gullotta, Francesca; Gioia, Magda; Coletta, Massimo; Fasano, Mauro

2011-01-01

Research highlights: → Human serum heme-albumin displays globin-like properties. → O 2 -mediated oxidation of ferrous nitrosylated human serum heme-albumin. → Allosteric modulation of human serum heme-albumin reactivity. → Rifampicin is an allosteric effector of human serum heme-albumin. → Human serum heme-albumin is a ROS and NOS scavenger. -- Abstract: Human serum heme-albumin (HSA-heme-Fe) displays globin-like properties. Here, kinetics of O 2 -mediated oxidation of ferrous nitrosylated HSA-heme-Fe (HSA-heme-Fe(II)-NO) is reported. Values of the first-order rate constants for O 2 -mediated oxidation of HSA-heme-Fe(II)-NO (i.e., for ferric HSA-heme-Fe formation) and for NO dissociation from HSA-heme-Fe(II)-NO (i.e., for NO replacement by CO) are k = 9.8 x 10 -5 and 8.3 x 10 -4 s -1 , and h = 1.3 x 10 -4 and 8.5 x 10 -4 s -1 , in the absence and presence of rifampicin, respectively, at pH = 7.0 and T = 20.0 o C. The coincidence of values of k and h indicates that NO dissociation represents the rate limiting step of O 2 -mediated oxidation of HSA-heme-Fe(II)-NO. Mixing HSA-heme-Fe(II)-NO with O 2 does not lead to the formation of the transient adduct(s), but leads to the final ferric HSA-heme-Fe derivative. These results reflect the fast O 2 -mediated oxidation of ferrous HSA-heme-Fe and highlight the role of drugs in modulating allosterically the heme-Fe-atom reactivity.

Formation of iron oxides from acid mine drainage and magnetic separation of the heavy metals adsorbed iron oxides

Energy Technology Data Exchange (ETDEWEB)

Kwon, Hee Won; Kim, Jeong Jin; Kim, Young Hun [Andong National University, Andong (Korea, Republic of); Ha, Dong Woo [Korea Electrotechnology Research Institute, Changwon (Korea, Republic of)

2016-03-15

There are a few thousand abandoned metal mines in South Korea. The abandoned mines cause several environmental problems including releasing acid mine drainage (AMD), which contain a very high acidity and heavy metal ions such as Fe, Cu, Cd, Pb, and As. Iron oxides can be formed from the AMD by increasing the solution pH and inducing precipitation. Current study focused on the formation of iron oxide in an AMD and used the oxide for adsorption of heavy metals. The heavy metal adsorbed iron oxide was separated with a superconducting magnet. The duration of iron oxide formation affected on the type of mineral and the degree of magnetization. The removal rate of heavy metal by the adsorption process with the formed iron oxide was highly dependent on the type of iron oxide and the solution pH. A high gradient magnetic separation (HGMS) system successfully separated the iron oxide and harmful heavy metals.

Effect of dietary iron source and iron status on iron bioavailability tests in the rat

International Nuclear Information System (INIS)

Zhang, D.; Hendricks, D.G.; Mahoney, A.W.

1986-01-01

Weanling male rats were made anemic in 7 days by feeding a low iron diet and bleeding. Healthy rats were fed the low iron diet supplemented with ferrous sulfate (29 ppm Fe). Each group was subdivided and fed for 10 days on test diets containing about 29 ppm iron that were formulated with meat:spinach mixtures or meat:soy mixtures to provided 100:0, 75:25, 50:50, 25:75, or 0:100% of the dietary iron from these sources or from a ferrous sulfate diet. After 3 days on the diets all rats were dosed orally with 2 or 5 micro curries of 59 Fe after a 18 hour fast and refeeding for 1.5 hours. Iron status influenced liver iron, carcass iron, liver radio activity and percent of radioactive dose retained. Diet influenced fecal iron and apparent absorption of iron. In iron bioavailability studies assessment methodology and iron status of the test subject greatly influences the estimates of the value of dietary sources of iron

Combined chemical-biological treatment for prevention/rehabilitation of clogged wells by an iron-oxidizing bacterium.

Science.gov (United States)

Gino, Efrat; Starosvetsky, Jeanna; Kurzbaum, Eyal; Armon, Robert

2010-04-15

Groundwater wells containing large concentrations of ferrous iron face serious clogging problems as a result of biotic iron oxidation. Following a short time after their start off, wells get clogged, and their production efficiency drop significantly up to a total obstruction, making cleanup and rehabilitation an economic burden. The present study was undertaken to test an experimental combined treatment (chemical and biological) for future prevention or rehabilitation of clogged wells. Sphaerotilus natans (an iron-oxidizing bacterium) freshly isolated from a deep well was grown to form biofilms on two systems: coupons and sand buried miniature wedge wire screen baskets. A combined chemical-biological treatment, applied at laboratory scale by use of glycolic acid (2%) and isolated bacteriophages against Sphaerotilus natans (SN1 and ER1-a newly isolated phage) at low multiplicity of infection (MOI), showed inhibition of biofilm formation and inactivation of the contaminant bacteria. In addition to complete inactivation of S. natans planktonic bacteria by the respective phages, earlier biofilm treatment with reduced glycolic acid concentration revealed efficient exopolysaccharide (EPS) digestion allowing phages to be increasingly efficient against biofilm matrix bacteria. Utilization of this combined treatment revealed clean surfaces of a model stainless steel wedge wire screen baskets (commonly used in wells) for up to 60 days.

Accelerated dissolution of iron oxides in ice

Directory of Open Access Journals (Sweden)

D. Jeong

2012-11-01

Full Text Available Iron dissolution from mineral dusts and soil particles is vital as a source of bioavailable iron in various environmental media. In this work, the dissolution of iron oxide particles trapped in ice was investigated as a new pathway of iron supply. The dissolution experiments were carried out in the absence and presence of various organic complexing ligands under dark condition. In acidic pH conditions (pH 2, 3, and 4, the dissolution of iron oxides was greatly enhanced in the ice phase compared to that in water. The dissolved iron was mainly in the ferric form, which indicates that the dissolution is not a reductive process. The extent of dissolved iron was greatly affected by the kind of organic complexing ligands and the surface area of iron oxides. The iron dissolution was most pronounced with high surface area iron oxides and in the presence of strong iron binding ligands. The enhanced dissolution of iron oxides in ice is mainly ascribed to the "freeze concentration effect", which concentrates iron oxide particles, organic ligands, and protons in the liquid like ice grain boundary region and accelerates the dissolution of iron oxides. The ice-enhanced dissolution effect gradually decreased when decreasing the freezing temperature from −10 to −196 °C, which implies that the presence and formation of the liquid-like ice grain boundary region play a critical role. The proposed phenomenon of enhanced dissolution of iron oxides in ice may provide a new pathway of bioavailable iron production. The frozen atmospheric ice with iron-containing dust particles in the upper atmosphere thaws upon descending and may provide bioavailable iron upon deposition onto the ocean surface.

Synthesis, characterization and mechanistic insights of mycogenic iron oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Bhargava, Arpit; Jain, Navin; Manju Barathi L [Birla Institute of Technology and Science, Centre for Biotechnology, Department of Biological Sciences (India); Akhtar, Mohd Sayeed [Jimma University, Department of Applied Microbiology, College of Natural Sciences (Ethiopia); Yun, Yeoung-Sang [Chonbuk National University, Division of Environmental and Chemical Engineering (Korea, Republic of); Panwar, Jitendra, E-mail: drjitendrapanwar@yahoo.co.in [Birla Institute of Technology and Science, Centre for Biotechnology, Department of Biological Sciences (India)

2013-11-15

In the present study, extracellular synthesis of iron oxide nanoparticles (IONPs) was achieved using Aspergillus japonicus isolate AJP01. The isolate demonstrated its ability to hydrolyze the precursor salt solution, a mixture of iron cyanide complexes, under ambient conditions. Hydrolysis of these complexes released ferric and ferrous ions, which underwent protein-mediated coprecipitation and controlled nucleation resulting in the formation of IONPs. Transmission electron microscopy, selected area electron diffraction pattern, energy dispersive spectroscopy and grazing incidence X-ray diffraction analysis confirmed the mycosynthesis of IONPs. The synthesized particles were cubic in shape with a size range of 60–70 nm with crystal structure corresponding to magnetite. Scanning electron microscopy analysis revealed the absence of IONPs on fungal biomass surface, indicating the extracellular nature of synthesis. Fourier transform infrared spectroscopy confirmed the presence of proteins on as-synthesised IONPs, which may confer their stability. Preliminary investigation indicated the role of proteins in the synthesis and stabilization of IONPs. On the basis of present findings, a probable mechanism for synthesis of IONPs is suggested. The simplicity and versatility of the present approach can be utilized for the synthesis of other nanomaterials.

Monothioarsenate Occurrence in Bangladesh Groundwater and Its Removal by Ferrous and Zero-Valent Iron Technologies.

Science.gov (United States)

Planer-Friedrich, Britta; Schaller, Jörg; Wismeth, Fabian; Mehlhorn, Judith; Hug, Stephan J

2018-05-15

In most natural groundwaters, sulfide concentrations are low, and little attention has been paid to potential occurrence of thioarsenates (As V S n -II O 4- n 3- with n = 1-4). Thioarsenate occurrence in groundwater could be critical with regard to the efficiency of iron (Fe)-based treatment technologies because previous studies reported less sorption of thioarsenates to preformed Fe-minerals compared to arsenite and arsenate. We analyzed 273 groundwater samples taken from different wells in Bangladesh over 1 year and detected monothioarsenate (MTA), likely formed via solid-phase zero-valent sulfur, in almost 50% of all samples. Concentrations ranged up to >30 μg L -1 (21% of total As). MTA removal by locally used technologies in which zero-valent or ferrous Fe is oxidized by aeration and As sorbs or coprecipitates with the forming Fe(III)hydroxides was indeed lower than for arsenate. The presence of phosphate required up to three times as much Fe(II) for comparable MTA removal. However, in contrast to previous sorption studies on preformed Fe minerals, MTA removal, even in the presence of phosphate, was still higher than that of arsenite. The more efficient MTA removal is likely caused by a combination of coprecipitation and adsorption rendering the tested Fe-based treatment technologies suitable for As removal also in the presence of MTA.

Iron, Oxidative Stress and Gestational Diabetes

Directory of Open Access Journals (Sweden)

Taifeng Zhuang

2014-09-01

Full Text Available Both iron deficiency and hyperglycemia are highly prevalent globally for pregnant women. Iron supplementation is recommended during pregnancy to control iron deficiency. The purposes of the review are to assess the oxidative effects of iron supplementation and the potential relationship between iron nutrition and gestational diabetes. High doses of iron (~relative to 60 mg or more daily for adult humans can induce lipid peroxidation in vitro and in animal studies. Pharmaceutical doses of iron supplements (e.g., 10× RDA or more for oral supplements or direct iron supplementation via injection or addition to the cell culture medium for a short or long duration will induce DNA damage. Higher heme-iron intake or iron status measured by various biomarkers, especially serum ferritin, might contribute to greater risk of gestational diabetes, which may be mediated by iron oxidative stress though lipid oxidation and/or DNA damage. However, information is lacking about the effect of low dose iron supplementation (≤60 mg daily on lipid peroxidation, DNA damage and gestational diabetes. Randomized trials of low-dose iron supplementation (≤60 mg daily for pregnant women are warranted to test the relationship between iron oxidative stress and insulin resistance/gestational diabetes, especially for iron-replete women.

Ferroxidase-Mediated Iron Oxide Biomineralization

DEFF Research Database (Denmark)

Zeth, Kornelius; Hoiczyk, Egbert; Okuda, Mitsuhiro

2016-01-01

Iron oxide biomineralization occurs in all living organisms and typically involves protein compartments ranging from 5 to 100nm in size. The smallest iron-oxo particles are formed inside dodecameric Dps protein cages, while the structurally related ferritin compartments consist of twice as many......, translocation, oxidation, nucleation, and storage, that are mediated by ferroxidase centers. Thus, compartmentalized iron oxide biomineralization yields uniform nanoparticles strictly determined by the sizes of the compartments, allowing customization for highly diverse nanotechnological applications....... identical protein subunits. The largest known compartments are encapsulins, icosahedra made of up to 180 protein subunits that harbor additional ferritin-like proteins in their interior. The formation of iron-oxo particles in all these compartments requires a series of steps including recruitment of iron...

Roentgenoelectronic investigation into oxidation of iron-chromium and iron-chromium-nickel alloys

International Nuclear Information System (INIS)

Akimov, A.G.; Rozenfel'd, I.L.; Kazanskij, L.P.; Machavariani, G.V.

1978-01-01

Kinetics of iron-chromium and iron-chromium-nickel alloy oxidation (of the Kh13 and Kh18N10T steels) in oxygen was investigated using X-ray electron spectroscopy. It was found that according to X-ray electron spectra chromium oxidation kinetics in the iron-chromium alloy differs significantly from oxidation kinetics of chromium pattern. Layer by layer X-ray electron analysis showed that chromium is subjected to a deeper oxidation as compared to iron, and accordingly, Cr 2 O 3 layer with pure iron impregnations is placed between the layer of mixed oxide (Fe 3 O 4 +Cr 2 O 3 ) and metal. A model of the iron-chromium alloy surface is suggested. The mixed oxide composition on the steel surface is presented as spinel Fesub(2+x)Crsub(1-x)Osub(y)

Gene Identification and Substrate Regulation Provide Insights into Sulfur Accumulation during Bioleaching with the Psychrotolerant Acidophile Acidithiobacillus ferrivorans

Science.gov (United States)

Liljeqvist, Maria; Rzhepishevska, Olena I.

2013-01-01

The psychrotolerant acidophile Acidithiobacillus ferrivorans has been identified from cold environments and has been shown to use ferrous iron and inorganic sulfur compounds as its energy sources. A bioinformatic evaluation presented in this study suggested that Acidithiobacillus ferrivorans utilized a ferrous iron oxidation pathway similar to that of the related species Acidithiobacillus ferrooxidans. However, the inorganic sulfur oxidation pathway was less clear, since the Acidithiobacillus ferrivorans genome contained genes from both Acidithiobacillus ferrooxidans and Acidithiobacillus caldus encoding enzymes whose assigned functions are redundant. Transcriptional analysis revealed that the petA1 and petB1 genes (implicated in ferrous iron oxidation) were downregulated upon growth on the inorganic sulfur compound tetrathionate but were on average 10.5-fold upregulated in the presence of ferrous iron. In contrast, expression of cyoB1 (involved in inorganic sulfur compound oxidation) was decreased 6.6-fold upon growth on ferrous iron alone. Competition assays between ferrous iron and tetrathionate with Acidithiobacillus ferrivorans SS3 precultured on chalcopyrite mineral showed a preference for ferrous iron oxidation over tetrathionate oxidation. Also, pure and mixed cultures of psychrotolerant acidophiles were utilized for the bioleaching of metal sulfide minerals in stirred tank reactors at 5 and 25°C in order to investigate the fate of ferrous iron and inorganic sulfur compounds. Solid sulfur accumulated in bioleaching cultures growing on a chalcopyrite concentrate. Sulfur accumulation halted mineral solubilization, but sulfur was oxidized after metal release had ceased. The data indicated that ferrous iron was preferentially oxidized during growth on chalcopyrite, a finding with important implications for biomining in cold environments. PMID:23183980

21 CFR 73.3125 - Iron oxides.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Iron oxides. 73.3125 Section 73.3125 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3125 Iron oxides. (a) Identity and specifications. The color additive iron oxides (CAS Reg. No. 1332-37-2), Color Index No. 77491, shall conform in...

Preparation of Magnetite Nanocrystals from Ferrous Sulphate Solution

International Nuclear Information System (INIS)

Cho Yu Mon; Tint Tint Kywe; Moe Moe Kyaw

2010-12-01

Magnetite (Fe3O4) nanoparticle were prepared by hydrothermal process in two ways, which would be used for production of copier toner.In this investigation, the first process was made from ferrous sulphate (FeSO4 . 7H2O) by using 10 M sodium hydroxide solution. In this method, magnetite nanoparticles were prepared by changing aeration time from 1 to 3 hr and heated at 90C for 15 min. The alternative process was carried out from ferrous sulphate (FeSO4.7H2O) by using 6.6 M sodium hydroxide solution and sodium silicate solution.Magnetite (black iron oxide) was synthesized by using different aeration times and reaction times. Aeration time was changed from 1 to 2 hr and reaction time was changed from 1 to 5.5 hr at 85 C. The magnetites obtained were examined by X-ray Diffraction (XRD) analysis and Scanning Electron Microscopy (SEM) technique. The average particle size range of magnetite nanoprticles were 90-120 nm and 120-150 nm in each process. The maximum yied percentages of magnetite based on FeSO4 in both processing were found to be 46.30% and 60.72%. The precent yields of magnetite in both preparation based on theoretical yields were 91.02% and 94.83% respectively.

Continuous sulfidogenic wastewater treatment with iron sulfide sludge oxidation and recycle.

Science.gov (United States)

Deng, Dongyang; Lin, Lian-Shin

2017-05-01

This study evaluated the technical feasibility of packed-bed sulfidogenic bioreactors dosed with ferrous chloride for continuous wastewater treatment over a 450-day period. In phase I, the bioreactors were operated under different combinations of carbon, iron, and sulfate mass loads without sludge recycling to identify optimal treatment conditions. A COD/sulfate mass ratio of 2 and a Fe/S molar ratio of 1 yielded the best treatment performance with COD oxidation rate of 786 ± 82 mg/(L⋅d), which resulted in 84 ± 9% COD removal, 94 ± 6% sulfate reduction, and good iron retention (99 ± 1%) under favorable pH conditions (6.2-7.0). In phase II, the bioreactors were operated under this chemical load combination over a 62-day period, during which 7 events of sludge collection, oxidation, and recycling were performed. The collected sludge materials contained both inorganic and organic matter with FeS and FeS 2 as the main inorganic constituents. In each event, the sludge materials were oxidized in an oxidizing basin before recycling to mix with the wastewater influent. Sludge recycling yielded enhanced COD removal (90 ± 6% vs. 75 ± 7%), and better effluent quality in terms of pH (6.8 ± 0.1 vs. 6.5 ± 0.2), iron (0.7 ± 0.5 vs. 1.9 ± 1.7 mg/L), and sulfide-S (0.3 ± 0.1 vs. 0.4 ± 0.1 mg/L) removal compared to the baseline operation without sludge recycling during phase II. This process exhibited treatment stability with reasonable variations, and fairly consistent sludge content over long periods of operation under a range of COD/sulfate and Fe/S ratios without sludge recycling. The bioreactors were found to absorb recycling-induced changes efficiently without causing elevated suspended solids in the effluents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Physiological Levels of Nitric Oxide Diminish Mitochondrial Superoxide. Potential Role of Mitochondrial Dinitrosyl Iron Complexes and Nitrosothiols

Directory of Open Access Journals (Sweden)

Sergey I. Dikalov

2017-11-01

Full Text Available Mitochondria are the major source of superoxide radicals and superoxide overproduction contributes to cardiovascular diseases and metabolic disorders. Endothelial dysfunction and diminished nitric oxide levels are early steps in the development of these pathological conditions. It is known that physiological production of nitric oxide reduces oxidative stress and inflammation, however, the precise mechanism of “antioxidant” effect of nitric oxide is not clear. In this work we tested the hypothesis that physiological levels of nitric oxide diminish mitochondrial superoxide production without inhibition of mitochondrial respiration. In order to test this hypothesis we analyzed effect of low physiological fluxes of nitric oxide (20 nM/min on superoxide and hydrogen peroxide production by ESR spin probes and Amplex Red in isolated rat brain mitochondria. Indeed, low levels of nitric oxide substantially attenuated both basal and antimycin A-stimulated production of reactive oxygen species in the presence of succinate or glutamate/malate as mitochondrial substrates. Furthermore, slow releasing NO donor DPTA-NONOate (100 μM did not change oxygen consumption in State 4 and State 3. However, the NO-donor strongly inhibited oxygen consumption in the presence of uncoupling agent CCCP, which is likely associated with inhibition of the over-reduced complex IV in uncoupled mitochondria. We have examined accumulation of dinitrosyl iron complexes and nitrosothiols in mitochondria treated with fast-releasing NO donor MAHMA NONOate (10 μM for 30 min until complete release of NO. Following treatment with NO donor, mitochondria were frozen for direct detection of dinitrosyl iron complexes using Electron Spin Resonance (ESR while accumulation of nitrosothiols was measured by ferrous-N-Methyl-D-glucamine dithiocarbamate complex, Fe(MGD2, in lysed mitochondria. Treatment of mitochondria with NO-donor gave rise to ESR signal of dinitrosyl iron complexes while ESR

Bismuth iron oxide thin films using atomic layer deposition of alternating bismuth oxide and iron oxide layers

Energy Technology Data Exchange (ETDEWEB)

Puttaswamy, Manjunath; Vehkamäki, Marko [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Kukli, Kaupo, E-mail: kaupo.kukli@helsinki.fi [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); University of Tartu, Institute of Physics, W. Ostwald 1, EE-50411 Tartu (Estonia); Dimri, Mukesh Chandra [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, EE-12618 Tallinn (Estonia); Kemell, Marianna; Hatanpää, Timo; Heikkilä, Mikko J. [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland); Mizohata, Kenichiro [University of Helsinki, Department of Physics, P.O. Box 64, FI-00014 Helsinki (Finland); Stern, Raivo [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, EE-12618 Tallinn (Estonia); Ritala, Mikko; Leskelä, Markku [University of Helsinki, Department of Chemistry, P.O. Box 55, FI-00014 Helsinki (Finland)

2016-07-29

Bismuth iron oxide films with varying contributions from Fe{sub 2}O{sub 3} or Bi{sub 2}O{sub 3} were prepared using atomic layer deposition. Bismuth (III) 2,3-dimethyl-2-butoxide, was used as the bismuth source, iron(III) tert-butoxide as the iron source and water vapor as the oxygen source. The films were deposited as stacks of alternate Bi{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} layers. Films grown at 140 °C to the thickness of 200–220 nm were amorphous, but crystallized upon post-deposition annealing at 500 °C in nitrogen. Annealing of films with intermittent bismuth and iron oxide layers grown to different thicknesses influenced their surface morphology, crystal structure, composition, electrical and magnetic properties. Implications of multiferroic performance were recognized in the films with the remanent charge polarization varying from 1 to 5 μC/cm{sup 2} and magnetic coercivity varying from a few up to 8000 A/m. - Highlights: • Bismuth iron oxide thin films were grown by atomic layer deposition at 140 °C. • The major phase formed in the films upon annealing at 500 °C was BiFeO{sub 3}. • BiFeO{sub 3} films and films containing excess Bi favored electrical charge polarization. • Slight excess of iron oxide enhanced saturative magnetization behavior.

Carbon-Supported Iron Oxide Particles

DEFF Research Database (Denmark)

Meaz, T.; Mørup, Steen; Koch, C. Bender

1996-01-01

A carbon black ws impregnated with 6 wt% iron using an aqueous solution of iron nitrate. The impregnated carbon was initially dried at 125 C. The effect of heating of the iron oxide phase was investigated at temperatures between 200 and 600 C using Mossbauer spectroscopy. All heat treatments were...... done in an oxygen-containing atmosphere. Ferrihydrite is formed and is stable at and below a temperature of 300 C. At 600 C small particles of maghemite is the dominant iron oxide. A transformation reaction is suggested....

Preparation of yttrium iron garnet (YIG) by modified domestic iron oxide

International Nuclear Information System (INIS)

Mozaffari, M.; Amighian

2002-01-01

Iron oxide by product of a local steel complex was modified to use for preparation of Yttrium iron garnet (YIG). The improvement was necessary to reduce impurities, especially the Si0 2 and Cl contents, which have deteriorative effects on magnetic properties and equipment used for preparation of the samples. The modified iron oxide was then mixed with Yttrium oxide of Merck Company in appropriate proportion to obtain a stoichiometric single phase YIG, using the conventional ceramic technique. XRD and SEM equipments were used to identify the resulting phases and microstructure respectively. Magnetic parameters were measured by VSM. Curie temperature of the samples was obtained by DTG (M) method. The results were compared with those obtained from samples that made by Merck iron oxide. There are small differences between the results. This was discussed according to extra pores and minute secondary phase in the samples made by domestic iron oxide. (Author)

Serum iron test

Science.gov (United States)

Fe+2; Ferric ion; Fe++; Ferrous ion; Iron - serum; Anemia - serum iron; Hemochromatosis - serum iron ... A blood sample is needed. Iron levels are highest in the morning. Your health care provider will likely have you do this test in the morning.

Application of tracer techniques and technical means in ferrous, non-ferrous and hydrometallurgy

International Nuclear Information System (INIS)

Chizhek, L.; Myshak, F.; Shtrba, J.

1979-01-01

Brief data are given about the results of joint investigations and developments of the problems of radioisotope methods and technical means application in ferrous and hydrometallurgy, obtained during the period of 1976-1977. Development of these problems was done in the frameworks of the plan of scientific and technical cooperation of the CMEA member-states and Yugoslavia. Results are given of the development of following themes: investigation of metallurgic processes by means of activation analysis; investidations of metallurgic processes by means of autoradiography and X-ray feuorescent analysis; control and automatization of metallurgic processes by means of radioisotope instruments; investigation of processes of melting of cast iron and steel as well as of processes of treatment of metals by means of the radioactive indicators method, activation analysis and radioisotope instruments; application of the radioisotope methods and technical means for investigation of processes of production of non-ferrous metals; application of the radioisotope methods for investigations of the hydrometallurgy processes [ru

Core-shell iron-iron oxide nanoparticles

DEFF Research Database (Denmark)

Kuhn, Luise Theil; Bojesen, A.; Timmermann, L.

2004-01-01

We present studies of the magnetic properties of core-shell iron-iron oxide nanoparticles. By combining Mossbauer and X-ray absorption spectroscopy we have been able to measure the change from a Fe3O4-like to a gamma-Fe2O3-like composition from the interface to the surface. Furthermore, we have...

Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

Science.gov (United States)

Scholz, Florian; Löscher, Carolin R.; Fiskal, Annika; Sommer, Stefan; Hensen, Christian; Lomnitz, Ulrike; Wuttig, Kathrin; Göttlicher, Jörg; Kossel, Elke; Steininger, Ralph; Canfield, Donald E.

2016-11-01

Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface. Even in the anoxic water of oxygen minimum zones, where iron solubility should be enhanced, most of the iron is rapidly re-precipitated. To constrain the mechanism(s) of iron removal in anoxic ocean regions we explored the sediment and water in the oxygen minimum zone off Peru. During our sampling campaign the water column featured two distinct redox boundaries separating oxic from nitrate-reducing (i.e., nitrogenous) water and nitrogenous from weakly sulfidic water. The sulfidic water mass in contact with the shelf sediment contained elevated iron concentrations >300 nM. At the boundary between sulfidic and nitrogenous conditions, iron concentrations dropped sharply to <20 nM coincident with a maximum in particulate iron concentration. Within the iron gradient, we found an increased expression of the key functional marker gene for nitrate reduction (narG). Part of this upregulation was related to the activity of known iron-oxidizing bacteria. Collectively, our data suggest that iron oxidation and removal is induced by nitrate-reducing microbes, either enzymatically through anaerobic iron oxidation or by providing nitrite for an abiotic reaction. Given the important role that iron plays in nitrogen fixation, photosynthesis and respiration, nitrate-dependent iron oxidation likely represents a key-link between the marine biogeochemical cycles of nitrogen, oxygen and carbon.

When Density Functional Approximations Meet Iron Oxides.

Science.gov (United States)

Meng, Yu; Liu, Xing-Wu; Huo, Chun-Fang; Guo, Wen-Ping; Cao, Dong-Bo; Peng, Qing; Dearden, Albert; Gonze, Xavier; Yang, Yong; Wang, Jianguo; Jiao, Haijun; Li, Yongwang; Wen, Xiao-Dong

2016-10-11

Three density functional approximations (DFAs), PBE, PBE+U, and Heyd-Scuseria-Ernzerhof screened hybrid functional (HSE), were employed to investigate the geometric, electronic, magnetic, and thermodynamic properties of four iron oxides, namely, α-FeOOH, α-Fe 2 O 3 , Fe 3 O 4 , and FeO. Comparing our calculated results with available experimental data, we found that HSE (a = 0.15) (containing 15% "screened" Hartree-Fock exchange) can provide reliable values of lattice constants, Fe magnetic moments, band gaps, and formation energies of all four iron oxides, while standard HSE (a = 0.25) seriously overestimates the band gaps and formation energies. For PBE+U, a suitable U value can give quite good results for the electronic properties of each iron oxide, but it is challenging to accurately get other properties of the four iron oxides using the same U value. Subsequently, we calculated the Gibbs free energies of transformation reactions among iron oxides using the HSE (a = 0.15) functional and plotted the equilibrium phase diagrams of the iron oxide system under various conditions, which provide reliable theoretical insight into the phase transformations of iron oxides.

Iron oxide surfaces

Science.gov (United States)

Parkinson, Gareth S.

2016-03-01

The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe3O4), maghemite (γ-Fe2O3), haematite (α-Fe2O3), and wüstite (Fe1-xO) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. Fe diffuses in and out from the bulk in response to the O2 chemical potential, forming sometimes complex intermediate phases at the surface. For example, α-Fe2O3 adopts Fe3O4-like surfaces in reducing conditions, and Fe3O4 adopts Fe1-xO-like structures in further reducing conditions still. It is argued that known bulk defect structures are an excellent starting point in building models for iron oxide surfaces. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe3O4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment. It is also an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed. The best understood iron oxide surface at present is probably Fe3O4(100); the structure is

Moessbauer Study of Electrodeposited Fe/Fe-Oxide Multilayers

International Nuclear Information System (INIS)

Kuzmann, E.; Homonnay, Z.; Klencsar, Z.; Vertes, A.; Lakatos-Varsanyi, M.; Miko, A.; Varga, L.K.; Kalman, E.; Nagy, F.

2005-01-01

Iron has been deposited electrochemically by short current pulses in Na-saccharin containing FeII-chloride and sulphate solution electrolytes. Combined electrochemical techniques with initial pulse plating of iron nanolayer and its subsequent anodic oxidation under potential control have been used for production of Fe/Fe-oxide multilayers. 57Fe CEM spectra of pulse plated iron revealed the presence of a minor doublet attributed mainly to γ-FeOOH in addition to the dominant sextet of α-iron. In the case of anodically oxidized pulse plated iron and of samples after repeated deposition of anodically oxidized pulse plated iron an additional minor doublet, assigned to ferrous chloride, also appears in the Moessbauer spectra. A significant change in the magnetic anisotropy of α-iron was observed with the anodic oxidation. The thickness of the layers were estimated from the CEM spectrum data by a modified computer program of the Liljequist method. The coercive field and the power loss versus frequency data showed that the pulse plated iron cores are good inductive elements up to several kHz frequencies

Bioavailability and the mechanisms of intestinal absorption of iron from ferrous ascorbate and ferric polymaltose in experimental animals

International Nuclear Information System (INIS)

Johnson, G.; Jacobs, P.

1990-01-01

The comparative bioavailability from matching quantities of iron in the form of ferrous ascorbate or ferric polymaltose was defined in rats. Studies were carried out in the intact animals under basal conditions and also when requirements for this metal were either increased or decreased by manipulating stores or erythropoietic activity. No significant difference was found in the total quantity of iron absorbed from either salt or complex under any of these circumstances, suggesting that the mucosal mechanism regulating the overall process was common to both. However, the rate of transfer from the lumen into portal blood was distinctive, reaching a maximum with salt at 30 min compared to 24 h for the complex. To explore the possibility that iron from the two sources was initially handled by different subcellular pathways, the radiolabeled compounds were instilled into loops of bowel that had been isolated between ligatures in vivo. Enterocytes were harvested and fractionated, and incorporation into ferritin and transferrin was determined using RIA. From salt, iron appeared rapidly in duodenal but not ileal ferritin, whereas mucosal transferrin increased under conditions of stimulated absorption, suggesting that this protein may act as a shuttle for the metal. In contrast, iron from polymaltose showed a cumulative incorporation into duodenal ferritin over time that correlated with iron absorption, defined by the appearance of radiolabel in the serum and in the carcass; a similar pattern was demonstrable in ileal mucosal cells. Conversely, binding of iron to transferrin was minimal. No iron polymaltose was found within the mucosal cells. It is suggested that the low rate of iron transfer from this ferric complex may reflect its extracellular breakdown in the lumen of the gastrointestinal tract

Temporal patterning of the potential induced by localized corrosion of iron passivity in acid media. Growth and breakdown of the oxide film described in terms of a point defect model.

Science.gov (United States)

Sazou, Dimitra; Pavlidou, Maria; Pagitsas, Michael

2009-10-21

This work analyses the nature of temporal patterning of the anodic potential induced by chlorides during polarization of iron under current-controlled conditions in acid solutions. It is shown that potential oscillations emerged as a result of the local chloride attack of a thin oxide layer, which covers the iron surface in its passive state. The mechanism by which both the local oxide breakdown and the subsequent localized active dissolution (pitting) occur is explained by considering a point defect model (PDM) developed to describe the oxide growth and breakdown. According to the PDM, chlorides occupy oxygen vacancies resulting in the inhibition of oxide growth and autocatalytic generation of cation vacancies that destabilize the oxide layer. Simultaneous transformation of the outer surface of the inner oxide layer to non-adherent ferrous chloride or oxo-chloride species leads to a further thinning of the oxide layer and its lifting-on from the iron surface. The process repeats again yielding sustained oscillations of the anodic potential. Analysis of the oscillatory response obtained under current-controlled conditions as a function of either the current or the time allows the suggestion of a set of alternate diagnostic criteria, which might be used to characterize localized corrosion of iron in acid solutions.

21 CFR 73.1200 - Synthetic iron oxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Synthetic iron oxide. 73.1200 Section 73.1200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically prepared...

21 CFR 73.200 - Synthetic iron oxide.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Synthetic iron oxide. 73.200 Section 73.200 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.200 Synthetic iron oxide. (a) Identity. (1) The color additive synthetic iron oxide consists of any one or any combination of synthetically prepared...

Photoinduced Oxidation of Arsenite to Arsenate on Ferrihydrite

Energy Technology Data Exchange (ETDEWEB)

N Bhandari; R Reeder; D Strongin

2011-12-31

The photochemistry of an aqueous suspension of the iron oxyhydroxide, ferrihydrite, in the presence of arsenite has been investigated using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray absorption near edge structure (XANES), and solution phase analysis. Both ATR-FTIR and XANES show that the exposure of ferrihydrite to arsenite in the dark leads to no change in the As oxidation state, but the exposure of this arsenite-bearing surface, which is in contact with pH 5 water, to light leads to the conversion of the majority of the adsorbed arsenite to the As(V) bearing species, arsenate. Analysis of the solution phase shows that ferrous iron is released into solution during the oxidation of arsenite. The photochemical reaction, however, shows the characteristics of a self-terminating reaction in that there is a significant suppression of this redox chemistry before 10% of the total iron making up the ferrihydrite partitions into solution as ferrous iron. The self-terminating behavior exhibited by this photochemical arsenite/ferrihydrite system is likely due to the passivation of the ferrihydrite surface by the strongly bound arsenate product.

Prospects for Ukrainian ferrous metals in the post-soviet period

Science.gov (United States)

Levine, R.M.; Bond, A.R.

1998-01-01

Two specialists on the mineral industries of the countries of the former USSR survey current problems confronting producers of ferrous metals in Ukraine and future prospects for domestic production and exports. A series of observations documenting the importance of ferrous metals production to Ukraine's economy is followed by sections describing investment plans and needs in the sector, and the role played by Ukraine within the iron and steel industry of the Soviet Union. The focus then turns to assessment of the current regional and global competitive position of Ukrainian producers for each of the major commodities of the sector-iron ore, manganese ore, ferroalloys, steel, and the products of the machine manufacturing and metal working industries. In conclusion, the paper discusses a potential regional industrial integration strategy analogous to that employed in the United States' Great Lakes/Midwest region, which possesses similar types of iron ore deposits and similar transport cost advantages and metallurgical and manufacturing industries. Journal of Economic Literature, Classification Numbers: F14, L61, L72. 1 table, 26 references.

Comparative study on the pharmacokinetics of inorganic and organic iron compounds in broiler chickens

Directory of Open Access Journals (Sweden)

Dimitrichka Dimitrova

2014-03-01

Full Text Available The pharmacokinetics of ferrous methionate and ferrous sulphate was investigated in broiler chickens after intravenous injection and crop intubation. The iron compounds were injected intravenously in v. brachialis. After 20-day “wash-out” period the ferrous methionate and ferrous sulphate were administered again by an elastic silicone tube into the crop. The serum concentrations of the iron were determined with bioanalyser. Two pharmacokinetic approaches were used – compartmental and non-compartmental analysis. After i.v. injection we found statistically significantly longer and better distribution of the iron contained in the ferrous methionate compared to the ferrous sulphate. The АUC0→∞ was statistically significantly higher in the ferrous methionate. In the alimentary tract of broiler chickens, ferrous methionate was absorbed more rapidly than ferrous sulfate. It was also distributed at a higher volume as compared to the ferrous sulfate.

Iron absorption in relation to iron status

International Nuclear Information System (INIS)

Magnusson, B.; Bjoern-Rasmussen, E.; Hallberg, L.; Rossander, L.

1981-01-01

The absorption from a 3 mg dose of ferrous iron was measured in 250 male subjects. The absorption was related to the log concentration of serum ferritin in 186 subjects of whom 99 were regular blood donors (r= -0.76), and to bone marrow haemosiderin grading in 52 subjects with varying iron status. The purpose was to try and establish a percentage absorption from such a dose that is representative of subjects who are borderline iron deficient. This information is necessary for food iron absorption studies in order (1) to calculate the absorption of iron from the diet at a given iron status and (2) compare the absorption of iron from different meals studied in different groups of subjects by different investigarors. The results suggest that an absorption of about 40% of a 3 mg reference dose of ferrous iron is given in a fasting state, roughly corresponds to the absorption in borderline-iron-deficient subjects. The results indicate that this 40% absorption value corresponds to a serum ferritin level of 30 μg/l and that food iron absorption in a group of subjects should be expressed preferably as the absorption corresponding to a reference-dose absorption of 45%, or possibly a serum ferritin level of 30 μg/l. (author)

Thermally stimulated iron oxide transformations and magnetic behaviour of cerium dioxide/iron oxide reactive sorbents

Energy Technology Data Exchange (ETDEWEB)

Luňáček, J., E-mail: jiri.lunacek@vsb.cz [Department of Physics, VŠB – Technical University of Ostrava, 17, listopadu 15/2172, 708 33 Ostrava-Poruba (Czech Republic); Department 606, VŠB – Technical University of Ostrava, 17, listopadu 15/2172, 708 33 Ostrava-Poruba (Czech Republic); Životský, O. [Department of Physics, VŠB – Technical University of Ostrava, 17, listopadu 15/2172, 708 33 Ostrava-Poruba (Czech Republic); Department 606, VŠB – Technical University of Ostrava, 17, listopadu 15/2172, 708 33 Ostrava-Poruba (Czech Republic); Jirásková, Y. [CEITEC IPM, Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Žižkova 22, 616 62 Brno (Czech Republic); Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Žižkova 22, 616 62 Brno (Czech Republic); Buršík, J. [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Žižkova 22, 616 62 Brno (Czech Republic); Janoš, P. [Faculty of the Environment, University of Jan Evangelista Purkyně, Králova Výšina 7, 400 96 Ústí nad Labem (Czech Republic)

2016-10-15

The present paper is devoted to detailed study of the magnetically separable sorbents based on a cerium dioxide/iron oxide composite annealed at temperatures T{sub a} = 773 K, 873 K, and 973 K. The X-ray diffraction and high resolution transmission electron microscopy are used to determine the phase composition and microstructure morphology. Mössbauer spectroscopy at room (300 K) and low (5 K) temperatures has contributed to more exact identification of iron oxides and their transformations Fe{sub 3}O{sub 4} → γ-Fe{sub 2}O{sub 3} (ε-Fe{sub 2}O{sub 3}) → α-Fe{sub 2}O{sub 3} in dependence on calcination temperature. Different iron oxide phase compositions and grain size distributions influence the magnetic characteristics determined from the room- and low-temperature hysteresis loop measurements. The results are supported by zero-field-cooled and field-cooled magnetization measurements allowing a quantitative estimation of the grain size distribution and its effect on the iron oxide transformations. - Highlights: •Magnetically separable sorbents based on a CeO{sub 2}/Fe{sub 2}O{sub 3} composite were investigated. •Microstructure of sorbents was determined by XRD, TEM and Mössbauer spectroscopy. •Magnetic properties were studied by hysteresis loops at room- and low-temperatures. •Phase transitions of iron oxides with increasing annealing temperature are observed.

Incorporating Geochemical And Microbial Kinetics In Reactive Transport Models For Generation Of Acid Rock Drainage

Science.gov (United States)

Andre, B. J.; Rajaram, H.; Silverstein, J.

2010-12-01

Acid mine drainage, AMD, results from the oxidation of metal sulfide minerals (e.g. pyrite), producing ferrous iron and sulfuric acid. Acidophilic autotrophic bacteria such as Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans obtain energy by oxidizing ferrous iron back to ferric iron, using oxygen as the electron acceptor. Most existing models of AMD do not account for microbial kinetics or iron geochemistry rigorously. Instead they assume that oxygen limitation controls pyrite oxidation and thus focus on oxygen transport. These models have been successfully used for simulating conditions where oxygen availability is a limiting factor (e.g. source prevention by capping), but have not been shown to effectively model acid generation and effluent chemistry under a wider range of conditions. The key reactions, oxidation of pyrite and oxidation of ferrous iron, are both slow kinetic processes. Despite being extensively studied for the last thirty years, there is still not a consensus in the literature about the basic mechanisms, limiting factors or rate expressions for microbially enhanced oxidation of metal sulfides. An indirect leaching mechanism (chemical oxidation of pyrite by ferric iron to produce ferrous iron, with regeneration of ferric iron by microbial oxidation of ferrous iron) is used as the foundation of a conceptual model for microbially enhanced oxidation of pyrite. Using literature data, a rate expression for microbial consumption of ferrous iron is developed that accounts for oxygen, ferrous iron and pH limitation. Reaction rate expressions for oxidation of pyrite and chemical oxidation of ferrous iron are selected from the literature. A completely mixed stirred tank reactor (CSTR) model is implemented coupling the kinetic rate expressions, speciation calculations and flow. The model simulates generation of AMD and effluent chemistry that qualitatively agrees with column reactor and single rock experiments. A one dimensional reaction

Exploring Microbial Iron Oxidation in Wetland Soils

Science.gov (United States)

Wang, J.; Muyzer, G.; Bodelier, P. L. E.; den Oudsten, F.; Laanbroek, H. J.

2009-04-01

Iron is one of the most abundant elements on earth and is essential for life. Because of its importance, iron cycling and its interaction with other chemical and microbial processes has been the focus of many studies. Iron-oxidizing bacteria (FeOB) have been detected in a wide variety of environments. Among those is the rhizosphere of wetland plants roots which release oxygen into the soil creating suboxic conditions required by these organisms. It has been reported that in these rhizosphere microbial iron oxidation proceeds up to four orders of magnitude faster than strictly abiotic oxidation. On the roots of these wetland plants iron plaques are formed by microbial iron oxidation which are involved in the sequestering of heavy metals as well organic pollutants, which of great environmental significance.Despite their important role being catalysts of iron-cycling in wetland environments, little is known about the diversity and distribution of iron-oxidizing bacteria in various environments. This study aimed at developing a PCR-DGGE assay enabling the detection of iron oxidizers in wetland habitats. Gradient tubes were used to enrich iron-oxidizing bacteria. From these enrichments, a clone library was established based on the almost complete 16s rRNA gene using the universal bacterial primers 27f and 1492r. This clone library consisted of mainly α- and β-Proteobacteria, among which two major clusters were closely related to Gallionella spp. Specific probes and primers were developed on the basis of this 16S rRNA gene clone library. The newly designed Gallionella-specific 16S rRNA gene primer set 122f/998r was applied to community DNA obtained from three contrasting wetland environments, and the PCR products were used in denaturing gradient gel electrophoresis (DGGE) analysis. A second 16S rRNA gene clone library was constructed using the PCR products from one of our sampling sites amplified with the newly developed primer set 122f/998r. The cloned 16S rRNA gene

Long distance electron transmission couples sulphur, iron, calcium and oxygen cycling in marine sediment

DEFF Research Database (Denmark)

Risgaard-Petersen, Nils; Nielsen, Lars Peter

sulfide oxidation leads to electric field formation, sulfide depletion and acidification of the upper centimeters of the sediment. This promoted ion migration and dissolution of carbonates and iron sulfides. Sulfide released from iron sulfides was the major e-donor in the system. Ferrous iron released...... from iron sulfides was to a large extend deposited in the oxic zone as iron oxides and Ca2+ eventually precipitates at the surface as due to high pH caused by cathodic oxygen reduction. The result show how long distance electron transmission allows oxygen to drive the allocation of important minerals...... geochemical alterations in the upper centimetres of the anoxic sediment: Sulphides were oxidized to sulphate in anoxic sediment layers. Electrons from this half-reaction were passed to the oxic layers cm above. In this way the domain of oxygen was extended far beyond it’s physically presence. Bioelectrical...

Comparison of bio-dissolution of spent Ni-Cd batteries by sewage sludge using ferrous ions and elemental sulfur as substrate.

Science.gov (United States)

Zhao, Ling; Zhu, Nan-Wen; Wang, Xiao-Hui

2008-01-01

Bioleaching of spent Ni-Cd batteries using acidified sewage sludge was carried out in a continuous flow two-step leaching system including an acidifying reactor and a leaching reactor. Two systems operated about 30d to achieve almost complete dissolution of heavy metals Ni, Cd and Co in four Ni-Cd batteries. Ferrous sulphate and elemental sulfur were used as two different substrates to culture indigenous thiobacilli in sewage sludge. pH and ORP of the acidifying reactor was stabilized around 2.3 and 334mV for the iron-oxidizing system and 1.2 and 390mV for the sulfur-oxidizing system. It was opposite to the acidifying reactor, the pH/ORP in the leaching reactor of the iron-oxidizing system was relatively lower/higher than that of the sulphur-oxidizing system in the first 17d. The metal dissolution, in the first 12-16d, was faster in the iron-oxidizing system than in the sulphur-oxidizing system due to the lower pH. In the iron-oxidizing system, the maximum solubilization of cadmium (2500mg l(-1)) and cobalt (260mg l(-1)) can be reached at day 6-8 and the most of metal nickel was leached in the first 16d. But in the sulphur-oxidizing system there was a lag period of 4-8d to reach the maximum solubilization of cadmium and cobalt. The maximum dissolution of nickel hydroxide (1400mg l(-1)) and metallic nickel (2300mg l(-1)) occurred at about day 12 and day 20, respectively.

Ferrous ion oxidations by ·H, ·OH and H2O2 in aerated FBX dosimetry system

International Nuclear Information System (INIS)

Gupta, B.L.; Nilekani, S.R.

1998-01-01

In the ferrous ion, benzoic acid and xylenol orange (FBX) dosimetric system, benzoic acid (BA) increases the G(Fe 3+ ) value. Xylenol orange (XO) controls the BA sensitized chain reaction as well as forms a complex with Fe 3+ . In the aerated FBX system each ·H, ·OH and H 2 O 2 oxidizes 8.5, 6.6 and 7.6 Fe 2+ ions, respectively; and these values respectively increase to 11.3, 7.6 and 8.6 in oxygenated solution. About 8% ·OH reacts with XO and the remaining with BA. The above fractional values are due to this competition. This ·OH reaction with XO oxidizes 1.8% and 2.1% ferrous ions only in aerated and oxygenated solutions, respectively. There is a competition between ·H reactions with O 2 and with BA, but both lead to the production of H 2 O 2 . The oxidation of Fe 2+ by ·OH reactions at different concentrations of H 2 O 2 is linear with absorbed dose while the ·H reactions make the oxidation of Fe 2+ non-linear with dose. This is due to competition reaction of H-adduct of BA between O 2 and Fe 3+

Bio-inspired Iron Catalysts for Hydrocarbon Oxidations

Energy Technology Data Exchange (ETDEWEB)

Que, Jr., Lawrence [Univ. of Minnesota, Minneapolis, MN (United States)

2016-03-22

Stereoselective oxidation of C–H and C=C bonds are catalyzed by nonheme iron enzymes. Inspired by these bioinorganic systems, our group has been exploring the use of nonheme iron complexes as catalysts for the oxidation of hydrocarbons using H2O2 as an environmentally friendly and atom-efficient oxidant in order to gain mechanistic insights into these novel transformations. In particular, we have focused on clarifying the nature of the high-valent iron oxidants likely to be involved in these transformations.

Direct Biohydrometallurgical Extraction of Iron from Ore

Energy Technology Data Exchange (ETDEWEB)

T.C. Eisele

2005-10-01

A completely novel approach to iron extraction was investigated, based on reductive leaching of iron by anaerobic bacteria. Microorganisms were collected from an anaerobic bog where natural seepage of dissolved iron was observed. This mixed culture was used to reduce insoluble iron in a magnetite ore to the soluble ferrous (Fe{sup +2}) state. While dissolution rates were slow, concentrations of dissolved iron as high as 3487 mg/l could be reached if sufficient time was allowed. A factorial study of the effects of trace nutrients and different forms of organic matter indicated that the best dissolution rates and highest dissolved iron concentrations were achieved using soluble carbohydrate (sucrose) as the bacterial food source, and that nutrients other than nitrogen, phosphorus, potassium, sodium, and acetate were not necessary. A key factor in reaching high levels of dissolved iron was maintaining a high level of carbon dioxide in solution, since the solubility of iron carbonates increases markedly as the quantity of dissolved carbon dioxide increases. Once the iron is dissolved, it has been demonstrated that the ferrous iron can then be electroplated from solution, provided that the concentration of iron is sufficiently high and the hydrogen ion concentration is sufficiently low. However, if the leaching solution is electrolyzed directly, organic matter precipitates at the cathode along with the metallic iron. To prevent this problem, the ferrous iron should be separated from the bulk solution in a more concentrated, purified form. One route to accomplishing this is to take advantage of the change in solubility of ferrous iron as a function of carbon dioxide concentration. By cycling the concentration of carbon dioxide in solution, it is possible to produce an iron-rich concentrate that should be suitable for electrolysis. This represents the first viable hydrometallurgical method for leaching iron directly from ore and producing metallic iron.

Method of removing nitrogen monoxide from a nitrogen monoxide-containing gas using a water-soluble iron ion-dithiocarbamate, xanthate or thioxanthate

Science.gov (United States)

Liu, D. Kwok-Keung; Chang, Shih-Ger

1987-08-25

The present invention relates to a method of removing of nitrogen monoxide from a nitrogen monoxide-containing gas which method comprises contacting a nitrogen oxide-containing gas with an aqueous solution of water soluble organic compound-iron ion chelate complex. The NO absorption efficiency of ferrous urea-dithiocarbamate and ferrous diethanolamine-xanthate as a function of time, oxygen content and solution ph is presented. 3 figs., 1 tab.

Amorphous structure of iron oxide of bacterial origin

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, Hideki; Fujii, Tatsuo [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); Kohara, Shinji [Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198 (Japan); Asaoka, Hiroshi [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); Kusano, Yoshihiro [Department of Fine and Applied Arts, Kurashiki University of Science and the Arts, Kurashiki, Okayama 712-8505 (Japan); Ikeda, Yasunori [Research Institute for Production Development, Sakyo-ku, Kyoto 606-0805 (Japan); Nakanishi, Makoto [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); Benino, Yasuhiko; Nanba, Tokuro [Graduate School of Environmental Science, Okayama University, Okayama 700-8530 (Japan); Takada, Jun, E-mail: jtakada@cc.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); JST, CREST, Okayama 700-8530 (Japan)

2012-12-14

In nature, there are various iron oxides produced by the water-habitant bacterial group called 'iron-oxidizing bacteria'. These iron oxides have been studied mainly from biological and geochemical perspectives. Today, attempts are made to use such iron oxides as novel functional materials in several applications. However, their quantitative structural characteristics are still unclear. We studied the structure of iron oxide of microtubular form consisting of amorphous nanoparticles formed by an iron-oxidizing bacterium, Leptothrix ochracea, using a combination of high-energy X-ray diffraction and reverse Monte Carlo simulation. We found that its structure consists of a framework of corner- and edge-sharing distorted FeO{sub 6} octahedral units, while SiO{sub 4} tetrahedral units are isolated in the framework. The results reveal the atomic arrangement of iron oxide of bacterial origin, which is essential for investigating its potential as a functional material. -- Highlights: Black-Right-Pointing-Pointer The amorphous structure of bacterial iron oxide was investigated. Black-Right-Pointing-Pointer The structure was simulated by high-energy X-ray diffraction and reverse Monte Carlo simulation. Black-Right-Pointing-Pointer The structure was constructed of a framework of corner- and edge-sharing distorted FeO{sub 6} octahedral units. Black-Right-Pointing-Pointer SiO{sub 4} tetrahedral units were distributed isolatedly in the framework of FeO{sub 6} octahedral units.

Diffusion of hydrogen in iron oxides

International Nuclear Information System (INIS)

Bruzzoni, P.

1993-01-01

The diffusion of hydrogen in transitions metals oxides has been recently studied at room temperature through the permeability electrochemical technique. This work studies thin oxide layers grown in air or in presence of oxidizing atmospheres at temperatures up to 200 deg C. The substrate was pure iron with different superficial treatments. It was observed that these oxides reduce up to three magnitudes orders, the hydrogen stationary flux through membranes of usual thickness in comparison with iron membranes free of oxide. (Author)

The GENIALL process for generation of nickel-iron alloys from nickel ores or mattes

International Nuclear Information System (INIS)

Diaz, G.; Frias, C.; Palma, J.

2001-01-01

A new process, called GENIALL (acronym of Generation of Nickel Alloys), for nickel recovery as ferronickel alloys from ores or mattes without previous smelting is presented in this paper. Its core technology is a new electrolytic concept, the ROSEL cell, for electrowinning of nickel-iron alloys from concentrated chloride solutions. In the GENIALL Process the substitution of iron-based solid wastes as jarosite, goethite or hematite, by saleable ferronickel plates provides both economic and environmental attractiveness. Another advantage is that no associated sulfuric acid plant is required. The process starts with leaching of the raw material (ores or mattes) with a solution of ferric chloride. The leachate liquor is purified by conventional methods like cementation or solvent extraction, to remove impurities or separate by-products like copper and cobalt. The purified solution, that contains a mixture of ferrous and nickel chlorides is fed to the cathodic compartment of the electrowinning cell, where nickel and ferrous ions are reduced together to form an alloy. Simultaneously, ferrous chloride is oxidized to ferric chloride in the anodic compartment, from where it is recycled to the leaching stage. The new electrolytic equipment has been developed and scaled up from laboratory to pilot prototypes with commercial size electrodes of 1 m 2 . Process operating conditions have been established in continuous runs at bench and pilot plant scale. The technology has shown a remarkable capacity to produce nickel-iron alloys of a wide range of compositions, from 10% to 80% nickel, just by adjusting the operating parameters. This emerging technology could be implemented in many processes in which iron and other non-ferrous metals are harmful impurities to be removed, or valuable metals to be recovered as a marketable iron alloy. Other potential applications of this technology are regeneration of spent etching liquors, and iron removal from aqueous effluents. (author)

Oxygen in the Martian atmosphere: Regulation of PO2 by the deposition of iron formations on Mars

Science.gov (United States)

Burns, Roger G.

1992-01-01

During Earth's early history, and prior to the evolution of its present day oxygenated atmosphere, extensive iron rich siliceous sedimentary rocks were deposited, consisting of alternating layers of silica (chert) and iron oxide minerals (hematite and magnetite). The banding in iron formations recorded changes of atmosphere-hydrosphere interactions near sea level in the ancient ocean, which induced the oxidation of dissolved ferrous iron, precipitation of insoluble ferric oxides and silica, and regulation of oxygen in Earth's early atmosphere. Similarities between the Archean Earth and the composition of the present day atmosphere on Mars, together with the pervasive presence of ferric oxides in the Martian regolith suggest that iron formation might also have been deposited on Mars and influenced the oxygen content of the Martian atmosphere. Such a possibility is discussed here with a view to assessing whether the oxygen content of the Martian atmosphere has been regulated by the chemical precipitation of iron formations on Mars.

Iron deficiency up-regulates iron absorption from ferrous sulphate but not ferric pyrophosphate and consequently food fortification with ferrous sulphate has relatively greater efficacy in iron-deficient individuals

NARCIS (Netherlands)

Zimmermann, M.B.; Biebinger, R.; Egli, I.; Zeder, C.; Hurrell, R.F.

2011-01-01

Fe absorption from water-soluble forms of Fe is inversely proportional to Fe status in humans. Whether this is true for poorly soluble Fe compounds is uncertain. Our objectives were therefore (1) to compare the up-regulation of Fe absorption at low Fe status from ferrous sulphate (FS) and ferric

Selectivity in the oxidative dehydrogenation of butene on zinc-iron oxide catalyst

Energy Technology Data Exchange (ETDEWEB)

Kung, H.H.; Kundalkar, B.; Kung, M.C.; Cheng, W.H.

1980-02-21

Adsorption, temperature-programed desorption, and pulse reaction studies of cis-2-butene and butadiene on spinel zinc ferrite by previously described methods provided evidence that the selectivity for oxidative dehydrogenation of butenes increases when zinc is added to the iron oxide catalyst because selective oxidation and complete oxidation proceed on separate sites, as they do on pure iron; because the density of sites for selective oxidation is higher and the density of sites for complete combustion is lower than on pure iron oxide; and because the activity of the combustion sites is lower.

The nanosphere iron mineral(s) in Mars soil

Science.gov (United States)

Banin, A.; Ben-Shlomo, T.; Margulies, L.; Blake, D. F.; Mancinelli, R. L.; Gehring, A. U.

1993-01-01

A series of surface-modified clays containing nanophase (np) iron/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these 'Mars-soil analogs' were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (gamma-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxyl mineral such as 'green rust', or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable meaghemite (gamma-Fe203) by mild heat treatment and then to nanophase hematite (aplha-Fe203) by extensive heat treatment. Their chemical reactivity offers a plausible mechanism for the somewhat puzzling observations of the Viking biology experiments. Their unique chemical reactivities are attributed to the combined catalytic effects of the iron oxide/oxyhydroxide and silicate phase surfaces. The mode of formation of these (nanophase) iron oxides on Mars is still unknown.

A sustainable process to utilize ferrous sulfate waste from titanium oxide industry by reductive decomposition reaction with pyrite

International Nuclear Information System (INIS)

Huang, Penghui; Deng, Shaogang; Zhang, Zhiye; Wang, Xinlong; Chen, Xiaodong; Yang, Xiushan; Yang, Lin

2015-01-01

Highlights: • A newly developed treating process of ferrous sulfate was proposed. • The reaction process was discussed by thermodynamic analysis. • Thermodynamic analysis was compared with experiments results. • The kinetic model of the decomposition reaction was determined. • The reaction mechanism of autocatalytic reactions was explored. - Abstract: Ferrous sulfate waste has become a bottleneck in the sustainable development of the titanium dioxide industry in China. In this study, we propose a new method for the reductive decomposition of ferrous sulfate waste using pyrite. Thermodynamics analysis, tubular reactor experiments, and kinetics analysis were performed to analyze the reaction process. The results of the thermodynamic simulation showed that the reaction process and products were different when molar ratio of FeSO_4/FeS_2 was changed. The suitable molar ratio of FeSO_4/FeS_2 was 8–12. The reaction temperature of ferrous sulfate with pyrite was 580–770 K and the main products were Fe_3O_4 and SO_2. The simulation results agreed well with the experimental results. The desulphurization rate reached 98.55% and main solid products were Fe_3O_4 at 823.15 K when mole ratio of FeSO_4/FeS_2 was 8. Nano-sized magnetite was obtained at this condition. The kinetic model was investigated by isoconversional methods. The average E value was 244.34 kJ mol"−"1. The ferrous sulfate decomposition process can be treated as autocatalytic reaction mechanism, which corresponded to the expanded Prout–Tompson (Bna) model. The reaction mechanism of autocatalytic reactions during the process of ferrous sulfate decomposition were explored, the products of Fe oxide substances are the catalyst components.

Electrochemical oxidation of iron and alkalinity generation for efficient sulfide control in sewers.

Science.gov (United States)

Lin, Hui-Wen; Kustermans, Caroline; Vaiopoulou, Eleni; Prévoteau, Antonin; Rabaey, Korneel; Yuan, Zhiguo; Pikaar, Ilje

2017-07-01

The addition of iron salts is one of the most commonly used dosing strategies for sulfide control in sewers. However, iron salts decrease the sewage pH which not only reduces the effectiveness of sulfide precipitation but also enhances the release of residual sulfide to the sewer atmosphere. Equally important, concentrated iron salt solutions are corrosive and their frequent transport, handling, and on-site storage often come with Occupational Health and Safety (OH&S) concerns. Here, we experimentally demonstrated a novel sulfide control approach using electrochemical systems with parallel placed iron electrodes. This enabled combining anodic dissolved iron species release with cathodic hydroxyl anion production, which alleviates all the aforementioned concerns. A long-term experiment was successfully carried out achieving an average sulfide removal efficiency of 95.4 ± 4.4% at low voltage input of 2.90 ± 0.54 V over the course of 8 weeks. This electrochemical method was demonstrated to successfully achieve efficient sulfide control. In addition, it increases the sewage pH, thereby overcoming the drawbacks associated with the pH decrease in the case of conventional iron salt dosing. Ferrous ions were produced at an overall coulombic efficiency (CE) of 98.2 ± 1.2%, whereas oxygen evolution and direct sulfide oxidation were not observed. Short-term experiments showed that increasing either inter-electrode gap or current density increased the cell voltage associated with the increase in the ohmic drop of the system. Overall, this study highlights the practical potential of in-situ generation of dissolved iron species and simultaneous hydroxyl anion generation for efficient sulfide control in sewers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of Microwave Heating on the Dielectric Properties and Components of Iron-Fortified Milk

Directory of Open Access Journals (Sweden)

Xiao-shu Tang

2017-01-01

Full Text Available With the iron-fortified milk as research object, this paper makes a research on the influence of iron on the dielectric properties and wave absorption properties and effect of nutritional components, such as casein and whey protein in milk, and thermostability in the process of microwave heating, and rapid heat transfer method in ferrous gluconate–milk and ferrous chloride–milk, respectively. The results show that the iron of ionic form has greater influence to convert microwave to heat energy and the effect of microwave absorption properties was greater for ferrous chloride than for ferrous gluconate at high concentration. The effect of different forms of iron on the composition of milk was different, and the composition of milk systems was more stable by microwave heating, but the rapid heat transfer method is superior in the aim of increasing the nutritional value of milk. The ferrous gluconate–milk system has a better thermal stability than ferrous chloride–milk system. From the aspect of dielectric induction, the paper discovers the response rules of iron and evaluates the microwave thermal safety of the traditional and the iron-fortified products by microwave heating.

Iron oxide reduction in methane-rich deep Baltic Sea sediments

DEFF Research Database (Denmark)

Egger, Matthias; Hagens, Mathilde; Sapart, Celia J.

2017-01-01

/L transition. Our results reveal a complex interplay between production, oxidation and transport of methane showing that besides organoclastic Fe reduction, oxidation of downward migrating methane with Fe oxides may also explain the elevated concentrations of dissolved ferrous Fe in deep Baltic Sea sediments...... profiles and numerical modeling, we propose that a potential coupling between Fe oxide reduction and methane oxidation likely affects deep Fe cycling and related biogeochemical processes, such as burial of phosphorus, in systems subject to changes in organic matter loading or bottom water salinity....

Metal ion binding to iron oxides

Science.gov (United States)

Ponthieu, M.; Juillot, F.; Hiemstra, T.; van Riemsdijk, W. H.; Benedetti, M. F.

2006-06-01

The biogeochemistry of trace elements (TE) is largely dependent upon their interaction with heterogeneous ligands including metal oxides and hydrous oxides of iron. The modeling of TE interactions with iron oxides has been pursued using a variety of chemical models. The objective of this work is to show that it is possible to model the adsorption of protons and TE on a crystallized oxide (i.e., goethite) and on an amorphous oxide (HFO) in an identical way. Here, we use the CD-MUSIC approach in combination with valuable and reliable surface spectroscopy information about the nature of surface complexes of the TE. The other objective of this work is to obtain generic parameters to describe the binding of the following elements (Cd, Co, Cu, Ni, Pb, and Zn) onto both iron oxides for the CD-MUSIC approach. The results show that a consistent description of proton and metal ion binding is possible for goethite and HFO with the same set of model parameters. In general a good prediction of almost all the collected experimental data sets corresponding to metal ion binding to HFO is obtained. Moreover, dominant surface species are in agreement with the recently published surface complexes derived from X-ray absorption spectroscopy (XAS) data. Until more detailed information on the structure of the two iron oxides is available, the present option seems a reasonable approximation and can be used to describe complex geochemical systems. To improve our understanding and modeling of multi-component systems we need more data obtained at much lower metal ion to iron oxide ratios in order to be able to account eventually for sites that are not always characterized in spectroscopic studies.

Geochemical patterns and microbial contribution to iron plaque formation in the rice plant rhizosphere

Science.gov (United States)

Maisch, Markus; Murata, Chihiro; Unger, Julia; Kappler, Andreas; Schmidt, Caroline

2015-04-01

Rice is the major food source for more than half of the world population and 80 percent of the worldwide rice cultivation is performed on water logged paddy soils. The establishment of reducing conditions in the soil and across the soil-water interface not only stimulates the microbial production and release of the greenhouse gas methane. These settings also create optimal conditions for microbial iron(III) reduction and therefore saturate the system with reduced ferrous iron. Through the reduction and dissolution of ferric minerals that are characterized by their high surface activity, sorbed nutrients and contaminants (e.g. arsenic) will be mobilized and are thus available for uptake by plants. Rice plants have evolved a strategy to release oxygen from their roots in order to prevent iron toxification in highly ferrous environments. The release of oxygen to the reduced paddy soil causes ferric iron plaque formation on the rice roots and finally increases the sorption capacity for toxic metals. To this date the geochemical and microbiological processes that control the formation of iron plaque are not deciphered. It has been hypothesized that iron(II)-oxidizing bacteria play a potential role in the iron(III) mineral formation along the roots. However, not much is known about the actual processes, mineral products, and geochemical gradients that establish within the rhizosphere. In the present study we have developed a growth set-up that allows the co-cultivation of rice plants and iron(II)-oxidizing bacteria, as well as the visual observation and in situ measurement of geochemical parameters. Oxygen and dissolved iron(II) gradients have been measured using microelectrodes and show geochemical hot spots that offer optimal growth conditions for microaerophilic iron(II) oxidizers. First mineral identification attempts of iron plaque have been performed using Mössbauer spectroscopy and microscopy. The obtained results on mineraology and crystallinity have been

Structural and magnetic properties of core-shell iron-iron oxide nanoparticles

DEFF Research Database (Denmark)

Kuhn, Luise Theil; Bojesen, A.; Timmermann, L.

2002-01-01

We present studies of the structural and magnetic properties of core-shell iron-iron oxide nanoparticles. alpha-Fe nanoparticles were fabricated by sputtering and subsequently covered with a protective nanocrystalline oxide shell consisting of either maghaemite (gamma-Fe2O3) or partially oxidized...... magnetite (Fe3O4). We observed that the nanoparticles were stable against further oxidation, and Mossbauer spectroscopy at high applied magnetic fields and low temperatures revealed a stable form of partly oxidized magnetite. The nanocrystalline structure of the oxide shell results in strong canting...... of the spin structure in the oxide shell, which thereby modifies the magnetic properties of the core-shell nanoparticles....

Iron oxides characterization by Moessbauer spectroscopy

International Nuclear Information System (INIS)

Basurto Sanchez, R.

1993-01-01

In this work rust development on low carbon wire surface after the conformation process at different temperatures was studied by Moessbauer spectroscopy. The characterization was made by determining the following spectral parameters; 1) Quadrupole splitting, 2) Isomer shift, and 3) Magnetic splitting. The area quantification determined the percentage amount of three different iron oxides. These iron oxides were: a) Wustite (Fe O), b) Hematite (Fe 2 O 3 ), and c) Magnetite (Fe 3 O 4 ) which were present in the rust studied. With the results it was possible to establish the best temperature to favor the development of each of these iron oxides. (Author)

Wastewater engineering applications of BioIronTech process based on the biogeochemical cycle of iron bioreduction and (biooxidation

Directory of Open Access Journals (Sweden)

Volodymyr Ivanov

2014-12-01

Full Text Available Bioreduction of Fe(III and biooxidation of Fe(II can be used in wastewater engineering as an innovative biotechnology BioIronTech, which is protected for commercial applications by US patent 7393452 and Singapore patent 106658 “Compositions and methods for the treatment of wastewater and other waste”. The BioIronTech process comprises the following steps: 1 anoxic bacterial reduction of Fe(III, for example in iron ore powder; 2 surface renovation of iron ore particles due to the formation of dissolved Fe2+ ions; 3 precipitation of insoluble ferrous salts of inorganic anions (phosphate or organic anions (phenols and organic acids; 4 (biooxidation of ferrous compunds with the formation of negatively, positively, or neutrally charged ferric hydroxides, which are good adsorbents of many pollutants; 5 disposal or thermal regeration of ferric (hydroxide. Different organic substances can be used as electron donors in bioreduction of Fe(III. Ferrous ions and fresh ferrous or ferric hydroxides that are produced after iron bioreduction and (biooxidation adsorb and precipitate diferent negatively charged molecules, for example chlorinated compounds of sucralose production wastewater or other halogenated organics, as well as phenols, organic acids, phosphate, and sulphide. Reject water (return liquor from the stage of sewage sludge dewatering on municipal wastewater treatment plants represents from 10 to 50% of phosphorus load when being recycled to the aeration tank. BioIronTech process can remove/recover more than 90% of phosphorous from this reject water thus replacing the conventional process of phosphate precipitation by ferric/ferrous salts, which are 20–100 times more expensive than iron ore, which is used in BioIronTech process. BioIronTech process can remarkably improve the aerobic and anaerobic treatments of municipal and industrial wastewaters, especially anaerobic digestion of lipid- and sulphate-containing food-processing wastewater. It

Fabrication and characterization of iron oxide dextran composite layers

Science.gov (United States)

Iconaru, S. L.; Predoi, S. A.; Beuran, M.; Ciobanu, C. S.; Trusca, R.; Ghita, R.; Negoi, I.; Teleanu, G.; Turculet, S. C.; Matei, M.; Badea, Monica; Prodan, A. M.

2018-02-01

Super paramagnetic iron oxide nanoparticles such as maghemite have been shown to exhibit antimicrobial properties [1-5]. Moreover, the iron oxide nanoparticles have been proposed as a potential magnetically controllable antimicrobial agent which could be directed to a specific infection [3-5]. The present research has focused on studies of the surface and structure of iron oxide dextran (D-IO) composite layers surface and structure. These composite layers were deposited on Si substrates. The structure of iron oxide dextran composite layers was investigated by X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) while the surface morphology was evaluated by Scanning Electron Microscopy (SEM). The structural characterizations of the iron oxide dextran composite layers revealed the basic constituents of both iron and dextran structure. Furthermore, the in vitro evaluation of the antifungal effect of the complex layers, which have been shown revealed to be active against C. albicans cells at distinct intervals of time, is exhibited. Our research came to confirm the fungicidal effect of iron oxide dextran composite layers. Also, our results suggest that iron oxide dextran surface may be used for medical treatment of biofilm associated Candida infections.

Enhancing the electrochemical oxidation of acid-yellow 36 azo dye using boron-doped diamond electrodes by addition of ferrous ion

International Nuclear Information System (INIS)

Villanueva-Rodriguez, M.; Hernandez-Ramirez, A.; Peralta-Hernandez, J.M.; Bandala, Erick R.; Quiroz-Alfaro, Marco A.

2009-01-01

This work shows preliminary results on the electrochemical oxidation process (EOP) using boron-doped diamond (BDD) electrode for acidic yellow 36 oxidation, a common azo dye used in textile industry. The study is centred in the synergetic effect of ferrous ions and hydroxyl free radicals for improving discoloration of azo dye. The assays were carried out in a typical glass cell under potentiostatic conditions. On experimental conditions, the EOP was able to partially remove the dye from the reaction mixture. The reaction rate increased significantly by addition of Fe 2+ (1 mM as ferrous sulphate) to the system and by (assumed) generation of ferrate ion [Fe(VI)] over BDD electrode. Ferrate is considered as a highly oxidizing reagent capable of removing the colorant from the reaction mixture, in synergistic action with the hydroxyl radicals produced on the BDD surface. Further increases in the Fe 2+ concentration lead to depletion of the reaction rate probably due to the hydroxyl radical scavenging effect of Fe 2+ excess in the system.

Iron appetite and latent learning in rats.

Science.gov (United States)

Woods, S C; Vasselli, J R; Milam, K M

1977-11-01

Two experiments are reported which show that rats are capable of forming an association between the presence of iron in a solution when it is not specifically needed and a subsequent state of iron deficiency. Specifically, rats were trained to lever press for water while thirsty. One group received ferrous ions in addition to the water. When these rats were subsequently rendered iron deficient, they lever pressed more under extinction conditions as a graded function of lower hemoglobin levels. Controls that either did not receive ferrous ions during training or received solutions other than ferrous solutions during training did not respond this way under extinction conditions. This is therefore a type of latent learning previously demonstrated only for sodium appetite.

Deactivation of iron oxide used in the steam-iron process to produce hydrogen

NARCIS (Netherlands)

Bleeker, M.F.; Veringa, H.J.; Kersten, Sascha R.A.

2009-01-01

In the steam-iron process pure hydrogen can be produced from any hydrocarbon feedstock by using a redox cycle of iron oxide. One of the main problems connected to the use of the iron oxide is the inherent structural changes that take place during oxygen loading and unloading leading to severe

Potentiometric and electrokinetic signatures of iron(II) interactions with (α,γ)-Fe2O3.

Science.gov (United States)

Toczydłowska, Diana; Kędra-Królik, Karolina; Nejbert, Krzysztof; Preočanin, Tajana; Rosso, Kevin M; Zarzycki, Piotr

2015-10-21

The electrochemical signatures of Fe(II) interactions with iron(III) oxides are poorly understood, despite their importance in controlling the amount of mobilized iron. Here, we report the potentiometric titration of α,γ-Fe2O3 oxides exposed to Fe(II) ions. We monitored in situ surface and ζ potentials, the ratio of mobilized ferric to ferrous, and the periodically analyzed nanoparticle crystal structure using X-ray diffraction. Electrokinetic potential reveals weak but still noticeable specific sorption of Fe(II) to the oxide surface under acidic conditions, and pronounced adsorption under alkaline conditions that results in a surface potential reversal. By monitoring the aqueous iron(II/III) fraction, we found that the addition of Fe(II) ions produces platinum electrode response consistent with the iron solubility-activity curve. Although, XRD analysis showed no evidence of γ-Fe2O3 transformations along the titration pathway despite iron cycling between aqueous and solid reservoirs, the magnetite formation cannot be ruled out.

Ceruloplasmin-ferroportin system of iron traffic in vertebrates

Institute of Scientific and Technical Information of China (English)

Giovanni; Musci; Fabio; Polticelli; Maria; Carmela; Bonaccorsi; di; Patti

2014-01-01

Safe trafficking of iron across the cell membrane is a delicate process that requires specific protein carriers. While many proteins involved in iron uptake by cells are known, only one cellular iron export protein has been identified in mammals: ferroportin(SLC40A1). Ceruloplasmin is a multicopper enzyme endowed with ferroxidase activity that is found as a soluble isoform in plasma or as a membrane-associated isoform in specific cell types. According to the currently accepted view, ferrous iron transported out of the cell by ferroportin would be safely oxidized by ceruloplasmin to facilitate loading on transferrin. Therefore, the ceruloplasminferroportin system represents the main pathway for cellular iron egress and it is responsible for physiological regulation of cellular iron levels. The most recent findings regarding the structural and functional features of ceruloplasmin and ferroportin and their relationship will be described in this review.

Studies on the absorption of iron after oral administration in piglets

International Nuclear Information System (INIS)

Thoren-Tolling, K.

1975-01-01

72 newborn piglets from 9 litters were used to determinate the retention and distribution in the body of labelled iron given either orally as ferrous fumarate (100 mg Fe 2+ ) or iron dextran (200 mg Fe 3+ ), or by injection as iron dextran (100 mg Fe 3+ ). About 25-30 % of the radioiron from a single oral dose of labelled ferrous fumarate (100 mg Fe 2+ ), and about 55-60 % from a single oral dose of labelled iron dextran (200 mg Fe 3+ ) were absorbed by the body. As iron is excreted throughout the experiment, only about 20% and 40-50% respectively of the radio-iron from these iron compounds were recovered 3 weeks after treatment. The total amounts of labelled iron retained in the body after oral administration of the same doses of these iron compounds, alone or in combination, were compared. A slight retardation of the absorption of ferrous iron was observed when iron dextran was administered simultaneeously. The absorption of iron dextran was not influenced by the simultaneous administration of ferrous fumarate. The importance of the liver as the main iron storage site was shown, and the rapid utilization of iron from storage sites, about 2-3 weeks after treatment was demonstrated. The concentration of labelled iron in urine and some lymphglands was measured. Only minute quantities of radio-iron were excreted in the urine throughout the entire experiment. The lymph nodes seem to act as iron stones after administration of iron dextran. The importance of the lymphatic tissue in absorption and storage of labelled iron is discussed. (author)

On the crystalline structures of iron oxides formed during the removal process of iron in water

International Nuclear Information System (INIS)

Cho, Bongyeon; Fujita, Kenji; Oda, Katsuro; Ino, Hiromitsu

1993-01-01

The iron oxide samples collected from both filtration and batch reactors were analysed by X-ray diffraction and Moessbauer spectroscopy. In the filtration of water containing iron, the oxidized form of iron was determined to be ferrihydrite. In contrast, in the batch experiment without filtration, iron was oxidized to microcrystalline goethite. (orig.)

Reactive oxygen species-related activities of nano-iron metal and nano-iron oxides.

Science.gov (United States)

Wu, Haohao; Yin, Jun-Jie; Wamer, Wayne G; Zeng, Mingyong; Lo, Y Martin

2014-03-01

Nano-iron metal and nano-iron oxides are among the most widely used engineered and naturally occurring nanostructures, and the increasing incidence of biological exposure to these nanostructures has raised concerns about their biotoxicity. Reactive oxygen species (ROS)-induced oxidative stress is one of the most accepted toxic mechanisms and, in the past decades, considerable efforts have been made to investigate the ROS-related activities of iron nanostructures. In this review, we summarize activities of nano-iron metal and nano-iron oxides in ROS-related redox processes, addressing in detail the known homogeneous and heterogeneous redox mechanisms involved in these processes, intrinsic ROS-related properties of iron nanostructures (chemical composition, particle size, and crystalline phase), and ROS-related bio-microenvironmental factors, including physiological pH and buffers, biogenic reducing agents, and other organic substances. Copyright © 2014. Published by Elsevier B.V.

Defluoridation by Bacteriogenic Iron Oxides: Sorption Studies

Science.gov (United States)

Evans, K.; Ferris, F.

2009-05-01

At concentrations above 1 mg/L, fluoride in drinking water can lead to dental and skeletal fluorosis, a disease that causes mottling of the teeth, calcification of ligaments, crippling bone deformities and many other physiological disorders that can, ultimately, lead to death. Conservative estimates are that fluorosis afflicts tens of millions of people worldwide. As there is no treatment for fluorosis, prevention is the only means of controlling the disease. While numerous defluoridation techniques have been explored, no single method has been found to be both effective and inexpensive enough to implement widely. Our research began in India, with a large-scale geochemical study of the groundwater in a fluoride-contaminated region of Orissa. Having developed a better understanding of the geochemical relationships that exist between fluoride and other parameters present in an affected area, as well as the complex relationships that arise among those parameters that can impact the presence of fluoride, we began investigating certain remediation scenarios involving iron oxides. A common approach to remediation involves the partitioning of fluoride from groundwater by sorption onto a variety of materials, one of the most effective of which is iron oxide whose surface area acts as a scavenger for fluoride. In the presence of iron oxidizing bacteria, the oxidation rate of iron has been shown to be ˜6 times greater than in their absence; fluoride should, therefore, be removed from an aqueous environment by bacteriogenic iron oxides (BIOS) much more quickly than by abiotic iron oxides. Most recently, sorption studies have been conducted using both BIOS and synthetic hydrous ferric oxides in order to compare the behavior between biotic and abiotic sorbents. These studies have provided sorption isotherms that allow comparison of fluoride removed by sorption to BIOS versus synthetic iron oxides. Sorption affinity constants have also been determined, which allow for the

Decoupling photochemical Fe(II) oxidation from shallow-water BIF deposition

DEFF Research Database (Denmark)

Konhauser, Kurt; Amskold, Larry; Lalonde, Stefan

2007-01-01

to the rise of atmospheric oxygen and the development of a protective ozone layer, the Earth's surface was subjected to high levels of ultraviolet radiation. Bulk ocean waters that were anoxic at this time could have supported high concentrations of dissolved Fe(II). Under such conditions, dissolved ferrous...... for biology [Fran??ois, L.M., 1986, Extensive deposition of banded iron formations was possible without photosynthesis. Nature 320, 352-354]. Here, we evaluate the potential importance of photochemical oxidation using a combination of experiments and thermodynamic models. The experiments simulate......-type systems, then we are driven to conclude that oxide-facies BIF are the product of a rapid, non-photochemical oxidative process, the most likely candidates being direct or indirect biological oxidation, and that a significant fraction of BIF could have initially been deposited as ferrous minerals. ?? 2007...

Reduction Behaviors of Carbon Composite Iron Oxide Briquette Under Oxidation Atmosphere

Energy Technology Data Exchange (ETDEWEB)

Lee, Ki-Woo; Kim, Kang-Min; Kwon, Jae-Hong; Han, Jeong-Whan [Inha University, Incheon (Korea, Republic of); Son, Sang-Han [POSCO, Pohang (Korea, Republic of)

2017-01-15

The carbon composite iron oxide briquette (CCB) is considered a potential solution to the upcoming use of low grade iron resources in the ironmaking process. CCB is able to reduce raw material cost by enabling the use of low grade powdered iron ores and coal. Additionally, the fast reduction of iron oxides by direct contact with coal can be utilized. In this study, the reduction behaviors of CCB were investigated in the temperature range of 200-1200 ℃ under oxidizing atmosphere. Briquettes were prepared by mixing iron ore and coal in a weight ratio of 8:2. Then reduction experiments were carried out in a mixed gas atmosphere of N{sub 2}, O{sub 2}, and CO{sub 2}. Compressive strength tests and quantitative analysis were performed by taking samples at each target temperature. In addition, the reduction degree depending on the reaction time was evaluated by off-gas analysis during the reduction test. It was found that the compressive strength and the metallization degree of the reduced briquettes increased with increases in the reaction temperature and holding time. However, it tended to decrease when the re-oxidation phenomenon was caused by injected oxygen. The degree of reduction reached a maximum value in 26 minutes. Therefore, the re-oxidation phenomenon becomes dominant after 26 minutes.

Genomic insights into microbial iron oxidation and iron uptake strategies in extremely acidic environments.

Science.gov (United States)

Bonnefoy, Violaine; Holmes, David S

2012-07-01

This minireview presents recent advances in our understanding of iron oxidation and homeostasis in acidophilic Bacteria and Archaea. These processes influence the flux of metals and nutrients in pristine and man-made acidic environments such as acid mine drainage and industrial bioleaching operations. Acidophiles are also being studied to understand life in extreme conditions and their role in the generation of biomarkers used in the search for evidence of existing or past extra-terrestrial life. Iron oxidation in acidophiles is best understood in the model organism Acidithiobacillus ferrooxidans. However, recent functional genomic analysis of acidophiles is leading to a deeper appreciation of the diversity of acidophilic iron-oxidizing pathways. Although it is too early to paint a detailed picture of the role played by lateral gene transfer in the evolution of iron oxidation, emerging evidence tends to support the view that iron oxidation arose independently more than once in evolution. Acidic environments are generally rich in soluble iron and extreme acidophiles (e.g. the Leptospirillum genus) have considerably fewer iron uptake systems compared with neutrophiles. However, some acidophiles have been shown to grow as high as pH 6 and, in the case of the Acidithiobacillus genus, to have multiple iron uptake systems. This could be an adaption allowing them to respond to different iron concentrations via the use of a multiplicity of different siderophores. Both Leptospirillum spp. and Acidithiobacillus spp. are predicted to synthesize the acid stable citrate siderophore for Fe(III) uptake. In addition, both groups have predicted receptors for siderophores produced by other microorganisms, suggesting that competition for iron occurs influencing the ecophysiology of acidic environments. Little is known about the genetic regulation of iron oxidation and iron uptake in acidophiles, especially how the use of iron as an energy source is balanced with its need to take up

Synthesis and characterization of dextran-coated iron oxide nanoparticles

Science.gov (United States)

Predescu, Andra Mihaela; Matei, Ecaterina; Berbecaru, Andrei Constantin; Pantilimon, Cristian; Drăgan, Claudia; Vidu, Ruxandra; Predescu, Cristian; Kuncser, Victor

2018-03-01

Synthesis and characterization of iron oxide nanoparticles coated with a large molar weight dextran for environmental applications are reported. The first experiments involved the synthesis of iron oxide nanoparticles which were coated with dextran at different concentrations. The synthesis was performed by a co-precipitation technique, while the coating of iron oxide nanoparticles was carried out in solution. The obtained nanoparticles were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectrometry, Fourier transform infrared spectroscopy and superconducting quantum interference device magnetometry. The results demonstrated a successful coating of iron oxide nanoparticles with large molar weight dextran, of which agglomeration tendency depended on the amount of dextran in the coating solution. SEM and TEM observations have shown that the iron oxide nanoparticles are of about 7 nm in size.

One step paired electrochemical synthesis of iron and iron oxide nanoparticles

Directory of Open Access Journals (Sweden)

Ordoukhanian Juliet

2016-09-01

Full Text Available In this study, a new one step paired electrochemical method is developed for simultaneous synthesis of iron and iron oxide nanoparticles. iron and iron oxide are prepared as cathodic and anodic products from iron (ii sulfate aqueous solution in a membrane divided electrolytic cell by the pulsed current electrosynthesis. Because of organic solvent-free and electrochemical nature of the synthesis, the process could be considered as green and environmentally friendly. The reduction of energy consumption and low cost are the other significant advantages of this new method that would have a great application potential in the chemical industry. The nanostructure of prepared samples was characterized by Fourier transform infrared spectroscopy (FT-IR, X-ray diffraction (XRD, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The magnetic properties were studied by vibrating sample magnetometer (VsM.

Preparation and characterization of polyindole - iron oxide nanocomposite electrolyte

International Nuclear Information System (INIS)

Rajasudha, G.; Stephen, A.; Narayanan, V.

2009-01-01

Full text: A novel polyindole-iron oxide containing LiClO 4 solid polymer electrolyte has been prepared. The diverse property of magnetic nanoparticle has elicited wide interest from the point of view of technological applications. Their properties are known to be strongly dependent on size, anisotropy and inter particle interactions. The proton conducting materials has received considerable attention as electrolyte materials in technological applications such as fuel cells, sensors and electrochromic display. In this work, polyindole-iron oxide nanocomposite containing LiClO 4 was prepared by in situ polymerization. The indole was polymerized in the presence of iron oxide, using ammonium peroxy disulphate as an oxidizing agent. The polyindole-iron oxide nanocomposite was characterized by XRD, IR, SEM, TGA and TEM. The iron oxide nano particles was incorporated into polyindole and was confirmed by XRD and Fourier transform infrared (FTIR) spectroscopy. The surface Morphology and thermal stability were studied by thermogravimetric analysis (TGA) and SEM respectively. The ionic conductivity of polyindole electrolyte was analyzed from impedance spectrum. The prepared polyindole-iron oxide nanocomposite could be used as solid electrolyte in lithium ion batteries

Direct Biohydrometallurgical Extraction of Iron from Ore. Final Technical Report

International Nuclear Information System (INIS)

T.C. Eisele

2005-01-01

A completely novel approach to iron extraction was investigated, based on reductive leaching of iron by anaerobic bacteria. Microorganisms were collected from an anaerobic bog where natural seepage of dissolved iron was observed. This mixed culture was used to reduce insoluble iron in a magnetite ore to the soluble ferrous (Fe +2 ) state. While dissolution rates were slow, concentrations of dissolved iron as high as 3487 mg/l could be reached if sufficient time was allowed. A factorial study of the effects of trace nutrients and different forms of organic matter indicated that the best dissolution rates and highest dissolved iron concentrations were achieved using soluble carbohydrate (sucrose) as the bacterial food source, and that nutrients other than nitrogen, phosphorus, potassium, sodium, and acetate were not necessary. A key factor in reaching high levels of dissolved iron was maintaining a high level of carbon dioxide in solution, since the solubility of iron carbonates increases markedly as the quantity of dissolved carbon dioxide increases. Once the iron is dissolved, it has been demonstrated that the ferrous iron can then be electroplated from solution, provided that the concentration of iron is sufficiently high and the hydrogen ion concentration is sufficiently low. However, if the leaching solution is electrolyzed directly, organic matter precipitates at the cathode along with the metallic iron. To prevent this problem, the ferrous iron should be separated from the bulk solution in a more concentrated, purified form. One route to accomplishing this is to take advantage of the change in solubility of ferrous iron as a function of carbon dioxide concentration. By cycling the concentration of carbon dioxide in solution, it is possible to produce an iron-rich concentrate that should be suitable for electrolysis. This represents the first viable hydrometallurgical method for leaching iron directly from ore and producing metallic iron

Direct Biohydrometallurgical Extraction of Iron from Ore. Final technical report

International Nuclear Information System (INIS)

T.C. Eisele

2005-01-01

A completely novel approach to iron extraction was investigated, based on reductive leaching of iron by anaerobic bacteria. Microorganisms were collected from an anaerobic bog where natural seepage of dissolved iron was observed. This mixed culture was used to reduce insoluble iron in a magnetite ore to the soluble ferrous (Fe +2 ) state. While dissolution rates were slow, concentrations of dissolved iron as high as 3487 mg/l could be reached if sufficient time was allowed. A factorial study of the effects of trace nutrients and different forms of organic matter indicated that the best dissolution rates and highest dissolved iron concentrations were achieved using soluble carbohydrate (sucrose) as the bacterial food source, and that nutrients other than nitrogen, phosphorus, potassium, sodium, and acetate were not necessary. A key factor in reaching high levels of dissolved iron was maintaining a high level of carbon dioxide in solution, since the solubility of iron carbonates increases markedly as the quantity of dissolved carbon dioxide increases. Once the iron is dissolved, it has been demonstrated that the ferrous iron can then be electroplated from solution, provided that the concentration of iron is sufficiently high and the hydrogen ion concentration is sufficiently low. However, if the leaching solution is electrolyzed directly, organic matter precipitates at the cathode along with the metallic iron. To prevent this problem, the ferrous iron should be separated from the bulk solution in a more concentrated, purified form. One route to accomplishing this is to take advantage of the change in solubility of ferrous iron as a function of carbon dioxide concentration. By cycling the concentration of carbon dioxide in solution, it is possible to produce an iron-rich concentrate that should be suitable for electrolysis. This represents the first viable hydrometallurgical method for leaching iron directly from ore and producing metallic iron

Development and optimization of iron- and zinc-containing nanostructured powders for nutritional applications

Energy Technology Data Exchange (ETDEWEB)

Hilty, F M; Hurrell, R F; Zimmermann, M B [Human Nutrition Laboratory, Institute of Food Science and Nutrition, ETH Zurich (Switzerland); Teleki, A; Buechel, R; Pratsinis, S E [Particle Technology Laboratory, Department of Mechanical and Process Engineering, ETH Zurich (Switzerland); Krumeich, F, E-mail: michael.zimmermann@ilw.agrl.ethz.c [Electron Microscopy Center (EMEZ), ETH Zurich (Switzerland)

2009-11-25

Reducing the size of low-solubility iron (Fe)-containing compounds to nanoscale has the potential to improve their bioavailability. Because Fe and zinc (Zn) deficiencies often coexist in populations, combined Fe/Zn-containing nanostructured compounds may be useful for nutritional applications. Such compounds are developed here and their solubility in dilute acid, a reliable indicator of iron bioavailability in humans, and sensory qualities in sensitive food matrices are investigated. Phosphates and oxides of Fe and atomically mixed Fe/Zn-containing (primarily ZnFe{sub 2}O{sub 4}) nanostructured powders were produced by flame spray pyrolysis (FSP). Chemical composition and surface area were systematically controlled by varying precursor concentration and feed rate during powder synthesis to increase solubility to the level of ferrous sulfate at maximum Fe and Zn content. Solubility of the nanostructured compounds was dependent on their particle size and crystallinity. The new nanostructured powders produced minimal color changes when added to dairy products containing chocolate or fruit compared to the changes produced when ferrous sulfate or ferrous fumarate were added to these foods. Flame-made Fe- and Fe/Zn-containing nanostructured powders have solubilities comparable to ferrous and Zn sulfate but may produce fewer color changes when added to difficult-to-fortify foods. Thus, these powders are promising for food fortification and other nutritional applications.

Development and optimization of iron- and zinc-containing nanostructured powders for nutritional applications

International Nuclear Information System (INIS)

Hilty, F M; Hurrell, R F; Zimmermann, M B; Teleki, A; Buechel, R; Pratsinis, S E; Krumeich, F

2009-01-01

Reducing the size of low-solubility iron (Fe)-containing compounds to nanoscale has the potential to improve their bioavailability. Because Fe and zinc (Zn) deficiencies often coexist in populations, combined Fe/Zn-containing nanostructured compounds may be useful for nutritional applications. Such compounds are developed here and their solubility in dilute acid, a reliable indicator of iron bioavailability in humans, and sensory qualities in sensitive food matrices are investigated. Phosphates and oxides of Fe and atomically mixed Fe/Zn-containing (primarily ZnFe 2 O 4 ) nanostructured powders were produced by flame spray pyrolysis (FSP). Chemical composition and surface area were systematically controlled by varying precursor concentration and feed rate during powder synthesis to increase solubility to the level of ferrous sulfate at maximum Fe and Zn content. Solubility of the nanostructured compounds was dependent on their particle size and crystallinity. The new nanostructured powders produced minimal color changes when added to dairy products containing chocolate or fruit compared to the changes produced when ferrous sulfate or ferrous fumarate were added to these foods. Flame-made Fe- and Fe/Zn-containing nanostructured powders have solubilities comparable to ferrous and Zn sulfate but may produce fewer color changes when added to difficult-to-fortify foods. Thus, these powders are promising for food fortification and other nutritional applications.

Development and optimization of iron- and zinc-containing nanostructured powders for nutritional applications.

Science.gov (United States)

Hilty, F M; Teleki, A; Krumeich, F; Büchel, R; Hurrell, R F; Pratsinis, S E; Zimmermann, M B

2009-11-25

Reducing the size of low-solubility iron (Fe)-containing compounds to nanoscale has the potential to improve their bioavailability. Because Fe and zinc (Zn) deficiencies often coexist in populations, combined Fe/Zn-containing nanostructured compounds may be useful for nutritional applications. Such compounds are developed here and their solubility in dilute acid, a reliable indicator of iron bioavailability in humans, and sensory qualities in sensitive food matrices are investigated. Phosphates and oxides of Fe and atomically mixed Fe/Zn-containing (primarily ZnFe2O4) nanostructured powders were produced by flame spray pyrolysis (FSP). Chemical composition and surface area were systematically controlled by varying precursor concentration and feed rate during powder synthesis to increase solubility to the level of ferrous sulfate at maximum Fe and Zn content. Solubility of the nanostructured compounds was dependent on their particle size and crystallinity. The new nanostructured powders produced minimal color changes when added to dairy products containing chocolate or fruit compared to the changes produced when ferrous sulfate or ferrous fumarate were added to these foods. Flame-made Fe- and Fe/Zn-containing nanostructured powders have solubilities comparable to ferrous and Zn sulfate but may produce fewer color changes when added to difficult-to-fortify foods. Thus, these powders are promising for food fortification and other nutritional applications.

Radiation-induced synthesis of gold, iron-oxide composite nanoparticles

International Nuclear Information System (INIS)

Seino, Satoshi; Yamamoto, Takao; Nakagawa, Takashi; Kinoshita, Takuya; Kojima, Takao; Taniguchi, Ryoichi; Okuda, Shuichi

2007-01-01

Composite nanoparticles consisting of magnetic iron oxide nanoparticles and gold nanoparticles were synthesized using gamma-rays or electron beam. Ionizing irradiation induces the generation of reducing species inside the aqueous solution, and gold ions are reduced to form metallic Au nanoparticles. The size of Au nanoparticles depended on the dose rate and the concentration of support iron oxide. The gold nanoparticles on iron oxide nanoparticles selectively adsorb biomolecules via Au-S bonding. By using magnetic property of the support iron oxide nanoparticles, the composite nanoparticles are expected as a new type of magnetic nanocarrier for biomedical applications. (author)

Hydrothermal oxidation in the Biwabik Iron Formation, MN, USA

Science.gov (United States)

Losh, Steven; Rague, Ryan

2018-02-01

Precambrian iron formations throughout the world, notably in Australia, Brazil, and South Africa, show evidence of hypogene (≥ 110 °C, mostly > 250 °C) oxidation, alteration, and silica dissolution as a result of tectonic or magmatic activity. Although hydrothermal oxidation has been proposed for the prototype Lake Superior-type iron formation, the Biwabik Iron Formation in Minnesota (USA), it has not been documented there. By examining oxidized and unoxidized Biwabik Iron Formation in three mines, including material from high-angle faults that are associated with oxidation, we document an early hypogene oxidation event ( 175 °C) involving medium-salinity aqueous fluids (8.4 ± 4.9 wt% NaCl equiv) that infiltrated iron formation along high-angle faults. At the Hibbing Taconite Mine, hydrothermal fluids oxidized iron carbonates and silicates near faults, producing goethite ± quartz. In contrast with much of the oxidized iron ores on the Mesabi Range, silica was not removed but rather recrystallized during this event, perhaps lying in a rock-dominated system at low cumulative fluid flux. During the hydrothermal oxidation event in the Hibbing Taconite deposit, quartz-filled microfractures and irregular inclusions commonly formed in coarse variably oxidized magnetite, currently the ore mineral: these inclusions degrade the ore by introducing excess silica in magnetic concentrate. Hydrothermal oxidation at Hibbing Taconite Mine is overprinted by later, relatively minor supergene oxidation both along faults and near the surface, which locally dissolved quartz. At the Fayal Reserve Mine, widespread silicate and carbonate gangue dissolution and iron oxidation was followed by precipitation of pyrite, Mn-siderite, apatite, and other minerals in void spaces, which prevented post-oxidation compaction and significant volume loss in the sampled rocks. Although definitive temperature data for this assemblage are needed, the weight of evidence indicates that this

Active removal of ibuprofen by Money plant enhanced by ferrous ions.

Science.gov (United States)

Chehrenegar, Behdad; Hu, Jiangyong; Ong, Say Leong

2016-02-01

In this study, the removal of ibuprofen (IBP), a pharmaceutical compound, from aqueous media by Money plant (Epipremnum aureum) was investigated. The effect of ferrous iron (Fe(2+)) on enhancing the IBP removal rate was also analyzed. The first-order removal rate constants showed higher values for lower IBP initial concentrations in the range of 0.20-0.28 d(-1) for an initial concentration of 125 μg L(-1) to 0.03-0.13 d(-1) for an initial concentration of 1000 μg L(-1). Introducing ferrous iron to the aqueous media enhanced the first-order removal rate constant up to 6.5 times in a 3 d time period. Along with the removal of IBP from the media, the endogenous concentration of H2O2 also decreased presumably by the production of hydroxyl radical (·OH). Reduction in the endogenous H2O2 concentration was recorded to be 38% and 98% in the absence and presence of Fe(2+) respectively in the first day and the H2O2 level remained considerably low until day 7 which then gradually increased slightly. Simultaneous reduction of IBP and endogenous H2O2 concentration could be due to the reaction of IBP with ·OH and presumably ·OH production itself accelerated via Fenton reaction. In addition, presence of sodium bicarbonate (NaHCO3) as ·OH scavenger in the system showed reduction of first-order removal rate constant from 1.30 d(-1) to 0.07 d(-1) which could be a possible evidence of biological advanced oxidation process which is believed to play an important role in phytoremediation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Oxidative Stress and the Homeodynamics of Iron Metabolism

Science.gov (United States)

Bresgen, Nikolaus; Eckl, Peter M.

2015-01-01

Iron and oxygen share a delicate partnership since both are indispensable for survival, but if the partnership becomes inadequate, this may rapidly terminate life. Virtually all cell components are directly or indirectly affected by cellular iron metabolism, which represents a complex, redox-based machinery that is controlled by, and essential to, metabolic requirements. Under conditions of increased oxidative stress—i.e., enhanced formation of reactive oxygen species (ROS)—however, this machinery may turn into a potential threat, the continued requirement for iron promoting adverse reactions such as the iron/H2O2-based formation of hydroxyl radicals, which exacerbate the initial pro-oxidant condition. This review will discuss the multifaceted homeodynamics of cellular iron management under normal conditions as well as in the context of oxidative stress. PMID:25970586

Sulfidation of alumina-supported iron and iron-molybdenum oxide catalysts

NARCIS (Netherlands)

Ramselaar, W.L.T.M.; Crajé, M.W.J.; Hadders, R.H.; Gerkema, E.; Beer, de V.H.J.; Kraan, van der A.M.

1990-01-01

The transition of alumina-supported iron and iron-molybdenum catalysts from the oxidic precursor to the sulfided catalysts was systematically studied by means of in-situ Mössbauer spectroscopy at room temperature. This enabled the adjudgement of various sulfidic phases in the sulfided catalysts. The

Iron Oxide Deposition from Aqueous Solution and Iron Formations on Mars

Science.gov (United States)

Catling, David; Moore, Jeff

2000-01-01

Iron formations are ancient, laminated chemical sediments containing at least 15 wt% Fe. We discuss possible mechanisms for their formation in aqueous environments on early Mars. Such iron oxide deposits may be detectable today.

Rare earths in iron and steelmaking and gaseous desulphurisation

International Nuclear Information System (INIS)

Kay, D.A.R.; Subramanian, S.V.; Meng, V.; Kumar, R.V.

1985-01-01

Rare earth (RE) additions, either as mischmetal or rare earth silicide, are used in many ladle treatment processes in modern ferrous metallurgy. In ironmaking they provide the basis for the control of graphite morphology in cast irons and in steelmaking additions are made to aluminum-killed steels for desulphurisation and the control of inclusion composition and morphology. Rare earth oxides may also be used in the desulphurisation of medium calorific value gaseous fuels and stack gases. In this paper, Ce-S-O and La-S-O phase stability diagrams are used to determine the role of the rare earths in the external processing of iron and steel, and gaseous desulphurisation

Phosphorus Retention (32P) by synthetic iron oxides

International Nuclear Information System (INIS)

Bittencourt, V.C.; Montanheiro, M.N.S.

1975-02-01

The P retention by iron oxides was characterized as a chemical adsorption process followed by a physical adsorption. The former process was very intense with initial amounts of added P but after a certain surface saturation is reached physical interaction occurs. It was supposed that the chemically adsorbed phosphate confers a negative charge on the iron oxides particles, which repels any further physical adsorbtion of the anion. However due to diffusion of phosphate ions into the internal layers of the iron oxides, their surface can retain further amounts of P [pt

Effects of sulfur in flooded paddy soils: Implications for iron chemistry and arsenic mobilization

Science.gov (United States)

Avancha, S.; Boye, K.

2013-12-01

In the Mekong delta in Cambodia, naturally occurring arsenic (amplified by erosion in the Himalaya Mountains) in paddy soils is mobilized during the seasonal flooding. As a consequence, rice grown on the flooded soils may take up arsenic and expose people eating the rice to this carcinogenic substance. Iron and sulfur both interact strongly with arsenic in paddy soils: iron oxides are strong adsorbents for arsenic in oxic conditions, and sulfur (in the form of sulfide) is a strong adsorbent under anoxic conditions. In the process of reductive dissolution of iron oxides, arsenic, which had been adsorbed to the iron oxides, is released. Therefore, higher levels of reduced iron (ferrous iron) will likely correlate with higher levels of mobilized arsenic. However, the mobilized arsenic may then co-precipitate with or adsorb to iron sulfides, which form under sulfate-reducing conditions and with the aid of certain microbes already present in the soil. In a batch experiment, we investigated how these processes correlate and which has the greatest influence on arsenic mobilization and potential plant availability. The experiment was designed to measure the effects of various sources of sulfur (dried rice straw, charred rice straw, and gypsum) on the iron and arsenic release in an arsenic-contaminated paddy soil from Cambodia under flooded conditions. The two types of rice straw were designed to introduce the same amount of organic sulfur (7.7 μg/g of soil), but different levels of available carbon, since carbon stimulates microbial activity in the soil. In comparison, two different levels of gypsum (calcium sulfate) were used, 7.7 and 34.65 μg/g of soil, to test the effect of directly available inorganic sulfate without carbon addition. The soil was flooded with a buffer solution at pH 7.07 in airtight serum vials and kept as a slurry on a shaker at 25 °C. We measured pH, alkalinity, ferrous iron, ferric iron, sulfide, sulfate, total iron, sulfur, and arsenic in the

Oral Iron Prophylaxis in Pregnancy: Not Too Little and Not Too Much!

Directory of Open Access Journals (Sweden)

Nils Milman

2012-01-01

Full Text Available An adequate supply of iron is essential for normal development of the fetus and newborn child. Iron deficiency and iron deficiency anemia (IDA during pregnancy increase the risk of preterm birth and low birth weight. Iron is important for development of the fetal brain and cognitive abilities of the newborn. Children born to iron-deficient mothers will start their lives suffering from iron deficiency or even IDA. Oral iron prophylaxis to pregnant women improves iron status and prevents development of IDA. The Danish National Board of Health has since 1992 recommended prophylactic oral iron supplements to all pregnant women and the currently advocated dose is 40–50 mg ferrous iron taken between meals from 10 weeks gestation to delivery. However, 30–40 mg ferrous iron is probably an adequate dose in most affluent societies. In developed countries, individual iron prophylaxis guided by iron status (serum ferritin has physiological advantages compared to general iron prophylaxis. In contrast, in most developing countries, general iron prophylaxis is indicated, and higher doses of oral iron, for example, 60 mg ferrous iron or even more should be recommended, according to the present iron status situation in the specific populations of women of fertile age and pregnant women.

Genome-Wide Search for Genes Required for Bifidobacterial Growth under Iron-Limitation

Science.gov (United States)

Lanigan, Noreen; Bottacini, Francesca; Casey, Pat G.; O'Connell Motherway, Mary; van Sinderen, Douwe

2017-01-01

Bacteria evolved over millennia in the presence of the vital micronutrient iron. Iron is involved in numerous processes within the cell and is essential for nearly all living organisms. The importance of iron to the survival of bacteria is obvious from the large variety of mechanisms by which iron may be acquired from the environment. Random mutagenesis and global gene expression profiling led to the identification of a number of genes, which are essential for Bifidobacterium breve UCC2003 survival under iron-restrictive conditions. These genes encode, among others, Fe-S cluster-associated proteins, a possible ferric iron reductase, a number of cell wall-associated proteins, and various DNA replication and repair proteins. In addition, our study identified several presumed iron uptake systems which were shown to be essential for B. breve UCC2003 growth under conditions of either ferric and/or ferrous iron chelation. Of these, two gene clusters encoding putative iron-uptake systems, bfeUO and sifABCDE, were further characterised, indicating that sifABCDE is involved in ferrous iron transport, while the bfeUO-encoded transport system imports both ferrous and ferric iron. Transcription studies showed that bfeUO and sifABCDE constitute two separate transcriptional units that are induced upon dipyridyl-mediated iron limitation. In the anaerobic gastrointestinal environment ferrous iron is presumed to be of most relevance, though a mutation in the sifABCDE cluster does not affect B. breve UCC2003's ability to colonise the gut of a murine model. PMID:28620359

Genome-Wide Search for Genes Required for Bifidobacterial Growth under Iron-Limitation

Directory of Open Access Journals (Sweden)

Noreen Lanigan

2017-05-01

Full Text Available Bacteria evolved over millennia in the presence of the vital micronutrient iron. Iron is involved in numerous processes within the cell and is essential for nearly all living organisms. The importance of iron to the survival of bacteria is obvious from the large variety of mechanisms by which iron may be acquired from the environment. Random mutagenesis and global gene expression profiling led to the identification of a number of genes, which are essential for Bifidobacterium breve UCC2003 survival under iron-restrictive conditions. These genes encode, among others, Fe-S cluster-associated proteins, a possible ferric iron reductase, a number of cell wall-associated proteins, and various DNA replication and repair proteins. In addition, our study identified several presumed iron uptake systems which were shown to be essential for B. breve UCC2003 growth under conditions of either ferric and/or ferrous iron chelation. Of these, two gene clusters encoding putative iron-uptake systems, bfeUO and sifABCDE, were further characterised, indicating that sifABCDE is involved in ferrous iron transport, while the bfeUO-encoded transport system imports both ferrous and ferric iron. Transcription studies showed that bfeUO and sifABCDE constitute two separate transcriptional units that are induced upon dipyridyl-mediated iron limitation. In the anaerobic gastrointestinal environment ferrous iron is presumed to be of most relevance, though a mutation in the sifABCDE cluster does not affect B. breve UCC2003's ability to colonise the gut of a murine model.

Iron-mediated soil carbon response to water-table decline in an alpine wetland

Science.gov (United States)

Wang, Yiyun; Wang, Hao; He, Jin-Sheng; Feng, Xiaojuan

2017-06-01

The tremendous reservoir of soil organic carbon (SOC) in wetlands is being threatened by water-table decline (WTD) globally. However, the SOC response to WTD remains highly uncertain. Here we examine the under-investigated role of iron (Fe) in mediating soil enzyme activity and lignin stabilization in a mesocosm WTD experiment in an alpine wetland. In contrast to the classic `enzyme latch' theory, phenol oxidative activity is mainly controlled by ferrous iron [Fe(II)] and declines with WTD, leading to an accumulation of dissolvable aromatics and a reduced activity of hydrolytic enzyme. Furthermore, using dithionite to remove Fe oxides, we observe a significant increase of Fe-protected lignin phenols in the air-exposed soils. Fe oxidation hence acts as an `iron gate' against the `enzyme latch' in regulating wetland SOC dynamics under oxygen exposure. This newly recognized mechanism may be key to predicting wetland soil carbon storage with intensified WTD in a changing climate.

No effect of H2O degassing on the oxidation state of hydrous rhyolite magmas: a comparison of pre- and post-eruptive Fe2+ concentrations in six obsidian samples from the Mexican and Cascade arcs

Science.gov (United States)

Waters, L.; Lange, R. A.

2011-12-01

The extent to which degassing affects the oxidation state of arc magmas is widely debated. Several researchers have examined how degassing of mixed H-C-O-S-Cl fluids may change the Fe3+/FeT ratio of magmas, and it has been proposed that degassing may induce either oxidation or reduction depending on the initial oxidation state. A commonly proposed oxidation reaction is related to H2O degassing: H2O (melt) + 2FeO (melt) = H2 (fluid) + Fe2O3 (melt). Another mechanism by which H2O degassing can affect the iron redox state is if dissolved water affects the activity of ferrous and/or ferric iron in the melt. Although Moore et al. (1995) presented experiments showing no evidence of an affect of dissolved water on the activity of the ferric-ferrous ratio in silicate melts, other experimental results (e.g., Baker and Rutherford, 1996; Gaillard et al., 2001; 2003) indicate that there may be such an effect in rhyolite liquids. It has long been understood that rhyolites, owing to their low total iron concentrations, are more sensitive than other magma types to degassing-induced change in redox state. Therefore, a rigorous test of whether H2O degassing affects the redox state of arc magmas is best evaluated on rhyolites. In this study, a comparison is made between the pre-eruptive (pre-degassing) Fe2+ concentrations in six, phenocryst-poor (volatiles, as indicated by the low loss on ignition values (LOI ≤ 0.7 wt%). In order to test how much oxidation of ferrous iron occurred as a consequence of that degassing, we measured the ferrous iron concentration in the bulk samples by titration, using the Wilson (1960) method, which was successfully tested again three USGS and one Canadian Geological Survey standards. Our results indicate no detectable change within analytical error between pre- and post-eruptive FeO concentrations, with an average deviation of 0.09 wt% and a maximum deviation of 0.15 wt%. Our results show that H2O degassing has no effect on the redox state of

Iron oxides as a cause of GPR reflections

NARCIS (Netherlands)

van Dam, R.L.; Schlager, W.; Dekkers, M.; Huisman, J.A.

2002-01-01

Iron oxides frequently occur as secondary precipitates in both modern and ancient sediments and may form bands or irregular patterns. We show from time-domain reflectometry (TDR) field studies that goethite iron-oxide precipitates significantly lower the electromagnetic wave velocity of sediments.

Oxidation of Fe(II) in rainwater.

Science.gov (United States)

Willey, J D; Whitehead, R F; Kieber, R J; Hardison, D R

2005-04-15

Photochemically produced Fe(II) is oxidized within hours under environmentally realistic conditions in rainwater. The diurnal variation between photochemical production and reoxidation of Fe(II) observed in our laboratory accurately mimics the behavior of ferrous iron observed in field studies where the highest concentrations of dissolved Fe(ll) occur in afternoon rain during the period of maximum sunlight intensity followed by gradually decreasing concentrations eventually returning to early morning pre-light values. The experimental work presented here, along with the results of kinetics studies done by others, suggests thatthe primary process responsible for the decline in photochemically produced Fe(II) concentrations is oxidation by hydrogen peroxide. This reaction is first order with respect to both the concentrations of Fe(II) and H2O2. The second-order rate constant determined for six different authentic rain samples varied over an order of magnitude and was always less than or equal to the rate constant determined for this reaction in simple acidic solutions. Oxidation of photochemically produced ferrous iron by other oxidants including molecular oxygen, ozone, hydroxyl radical, hydroperoxyl/superoxide radical, and hexavalent chromium were found to be insignificant under the conditions present in rainwater. This study shows that Fe(II) occurs as at least two different chemical species in rain; photochemically produced Fe(II) that is oxidized over time periods of hours, and a background Fe(II) that is protected against oxidation, perhaps by organic complexation, and is stable against oxidation for days. Because the rate of oxidation of photochemically produced Fe(II) does not increase with increasing rainwater pH, the speciation of this more labile form of Fe(II) is also not controlled by simple hydrolysis reactions.

Labeling Efficacy of Superparamagnetic Iron Oxide Nanoparticles to Human Neural Stem Cells: Comparison of Ferumoxides, Monocrystalline Iron Oxide, Cross-linked Iron Oxide (CLIO)-NH2 and tat-CLIO

International Nuclear Information System (INIS)

Song, Mi Yeoun; Moon, Woo Kyung; Kim, Yun Hee; Song, In Chan; Yoon, Byung Woo; Lim, Dong Yeol

2007-01-01

We wanted to compare the human neural stem cell (hNSC) labeling efficacy of different superparamagnetic iron oxide nanoparticles (SPIONs), namely, ferumoxides, monocrystalline iron oxide (MION), cross-linked iron oxide (CLIO)-NH 2 and tat-CLIO. The hNSCs (5x10 5 HB1F3 cells/ml) were incubated for 24 hr in cell culture media that contained 25 μg/ml of ferumoxides, MION or CLIO-NH 2 , and with or without poly-L-lysine (PLL) and tat-CLIO. The cellular iron uptake was analyzed qualitatively with using a light microscope and this was quantified via atomic absorption spectrophotometry. The visibility of the labeled cells was assessed with MR imaging. The incorporation of SPIONs into the hNSCs did not affect the cellular proliferations and viabilities. The hNSCs labeled with tat-CLIO showed the longest retention, up to 72 hr, and they contained 2.15± 0.3 pg iron/cell, which are 59 fold, 430 fold and six fold more incorporated iron than that of the hNSCs labeled with ferumoxides, MION or CLIO-NH 2 , respectively. However, when PLL was added, the incorporation of ferumoxides, MION or CLIO-NH 2 into the hNSCs was comparable to that of tat-CLIO. For MR imaging, hNSCs can be efficiently labeled with tat-CLIO alone or with a combination of ferumoxides, MION, CLIO-NH 2 and the transfection agent PLL

Labeling Efficacy of Superparamagnetic Iron Oxide Nanoparticles to Human Neural Stem Cells: Comparison of Ferumoxides, Monocrystalline Iron Oxide, Cross-linked Iron Oxide (CLIO)-NH2 and tat-CLIO

Science.gov (United States)

Song, Miyeoun; Kim, Yunhee; Lim, Dongyeol; Song, In-Chan; Yoon, Byung-Woo

2007-01-01

Objective We wanted to compare the human neural stem cell (hNSC) labeling efficacy of different superparamagnetic iron oxide nanoparticles (SPIONs), namely, ferumoxides, monocrystalline iron oxide (MION), cross-linked iron oxide (CLIO)-NH2 and tat-CLIO. Materials and Methods The hNSCs (5 × 105 HB1F3 cells/ml) were incubated for 24 hr in cell culture media that contained 25 µg/ml of ferumoxides, MION or CLIO-NH2, and with or without poly-L-lysine (PLL) and tat-CLIO. The cellular iron uptake was analyzed qualitatively with using a light microscope and this was quantified via atomic absorption spectrophotometry. The visibility of the labeled cells was assessed with MR imaging. Results The incorporation of SPIONs into the hNSCs did not affect the cellular proliferations and viabilities. The hNSCs labeled with tat-CLIO showed the longest retention, up to 72 hr, and they contained 2.15 ± 0.3 pg iron/cell, which are 59 fold, 430 fold and six fold more incorporated iron than that of the hNSCs labeled with ferumoxides, MION or CLIO-NH2, respectively. However, when PLL was added, the incorporation of ferumoxides, MION or CLIO-NH2 into the hNSCs was comparable to that of tat-CLIO. Conclusion For MR imaging, hNSCs can be efficiently labeled with tat-CLIO alone or with a combination of ferumoxides, MION, CLIO-NH2 and the transfection agent PLL. PMID:17923778

High pressure Moessbauer spectroscopy of perovskite iron oxide

International Nuclear Information System (INIS)

Nasu, Saburo; Suenaga, Tomoya; Morimoto, Shotaro; Kawakami, Takateru; Kuzushita, Kaori; Takano, Mikio

2003-01-01

High-pressure 57 Fe Moessbauer spectroscopy using a diamond anvil cell has been performed for perovskite iron oxides SrFeO 3 , CaFeO 3 and La 1/3 Sr 2/3 O 3 . The charge states and the magnetic dependency to pressure were determined. Pressure magnetic phase diagrams of these perovskite iron oxides are determined up to about 70 GPa. To be clear the magnetic ordered state, they are measured up to 7.8 T external magnetic fields at 4.5K. The phase transition of these perovskite oxides to ferromagnetisms with high magnetic ordered temperature is observed. In higher pressure, high spin-low spin transition of oxides besides CaFeO 3 is generated. The feature of Moessbauer spectroscopy, perovskite iron oxide and Moessbauer spectroscopy under high pressure are explained. (S.Y.)

Iron oxide nanoparticle synthesis in aqueous and membrane systems for oxidative degradation of trichloroethylene from water

Energy Technology Data Exchange (ETDEWEB)

Gui Minghui; Smuleac, Vasile [University of Kentucky, Department of Chemical and Materials Engineering (United States); Ormsbee, Lindell E. [University of Kentucky, Department of Civil Engineering (United States); Sedlak, David L. [University of California at Berkeley, Department of Civil and Environmental Engineering (United States); Bhattacharyya, Dibakar, E-mail: db@engr.uky.edu [University of Kentucky, Department of Chemical and Materials Engineering (United States)

2012-05-15

The potential for using hydroxyl radical (OH{sup Bullet }) reactions catalyzed by iron oxide nanoparticles (NPs) to remediate toxic organic compounds was investigated. Iron oxide NPs were synthesized by controlled oxidation of iron NPs prior to their use for contaminant oxidation (by H{sub 2}O{sub 2} addition) at near-neutral pH values. Cross-linked polyacrylic acid (PAA) functionalized polyvinylidene fluoride (PVDF) microfiltration membranes were prepared by in situ polymerization of acrylic acid inside the membrane pores. Iron and iron oxide NPs (80-100 nm) were directly synthesized in the polymer matrix of PAA/PVDF membranes, which prevented the agglomeration of particles and controlled the particle size. The conversion of iron to iron oxide in aqueous solution with air oxidation was studied based on X-ray diffraction, Moessbauer spectroscopy and BET surface area test methods. Trichloroethylene (TCE) was selected as the model contaminant because of its environmental importance. Degradations of TCE and H{sub 2}O{sub 2} by NP surface generated OH{sup Bullet} were investigated. Depending on the ratio of iron and H{sub 2}O{sub 2}, TCE conversions as high as 100 % (with about 91 % dechlorination) were obtained. TCE dechlorination was also achieved in real groundwater samples with the reactive membranes.

Iron oxide nanoparticle synthesis in aqueous and membrane systems for oxidative degradation of trichloroethylene from water

International Nuclear Information System (INIS)

Gui Minghui; Smuleac, Vasile; Ormsbee, Lindell E.; Sedlak, David L.; Bhattacharyya, Dibakar

2012-01-01

The potential for using hydroxyl radical (OH • ) reactions catalyzed by iron oxide nanoparticles (NPs) to remediate toxic organic compounds was investigated. Iron oxide NPs were synthesized by controlled oxidation of iron NPs prior to their use for contaminant oxidation (by H 2 O 2 addition) at near-neutral pH values. Cross-linked polyacrylic acid (PAA) functionalized polyvinylidene fluoride (PVDF) microfiltration membranes were prepared by in situ polymerization of acrylic acid inside the membrane pores. Iron and iron oxide NPs (80–100 nm) were directly synthesized in the polymer matrix of PAA/PVDF membranes, which prevented the agglomeration of particles and controlled the particle size. The conversion of iron to iron oxide in aqueous solution with air oxidation was studied based on X-ray diffraction, Mössbauer spectroscopy and BET surface area test methods. Trichloroethylene (TCE) was selected as the model contaminant because of its environmental importance. Degradations of TCE and H 2 O 2 by NP surface generated OH • were investigated. Depending on the ratio of iron and H 2 O 2 , TCE conversions as high as 100 % (with about 91 % dechlorination) were obtained. TCE dechlorination was also achieved in real groundwater samples with the reactive membranes.

Structural transformations of heat-treated bacterial iron oxide

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, Hideki, E-mail: hideki-h@cc.okayama-u.ac.jp [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); JST, CREST, Okayama 700-8530 (Japan); Fujii, Tatsuo [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); Kohara, Shinji [Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198 (Japan); Nakanishi, Koji [Office of Society-Academia Collaboration for Innovation, Kyoto University, Uji 611-0011 (Japan); Yogi, Chihiro [SR Center, Ritsumeikan University, Kusatsu, Shiga 525-8577 (Japan); Peterlik, Herwig [Faculty of Physics, University of Vienna, A-1090 Vienna (Austria); Nakanishi, Makoto [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); Takada, Jun [Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530 (Japan); JST, CREST, Okayama 700-8530 (Japan)

2015-04-01

A bacterial siliceous iron oxide microtubule (diameter: ca. 1 μm, 15Fe{sub 2}O{sub 3}·8SiO{sub 2}·P{sub 2}O{sub 5}·30H{sub 2}O) produced by Leptothrix ochracea was heat treated in air and its structural transformation was investigated in detail by microscopy, diffractometry, and spectroscopy. Although the heat-treated bacterial iron oxide retained its original microtubular structure, its nanoscopic, middle-range, and local structures changed drastically. Upon heat treatment, nanosized pores were formed and their size changed depending on temperature. The Fe–O–Si linkages were gradually cleaved with increasing temperature, causing the progressive separation of Fe and Si ions into iron oxide and amorphous silicate phases, respectively. Concomitantly, global connectivity and local structure of FeO{sub 6} octahedra in the iron oxide nanoparticles systematically changed depending on temperature. These comprehensive investigations clearly revealed various structural changes of the bacterial iron oxide which is an important guideline for the future exploration of novel bio-inspired materials. - Highlights: • Structural transformation of a bacterial iron oxide microtubule was investigated. • Si–O–Fe was cleaved with increasing temperature to form α-Fe{sub 2}O{sub 3}/silicate composite. • Crystallization to 2Fh started at 500 °C to give α-Fe{sub 2}O{sub 3} >700 °C. • FeO{sub 6} octahedra were highly distorted <500 °C. • Formation of face-sharing FeO{sub 6} was promoted >500 °C, releasing the local strain of FeO{sub 6}.

The fate of arsenic adsorbed on iron oxides in the presence of arsenite-oxidizing bacteria.

Science.gov (United States)

Zhang, Zhennan; Yin, Naiyi; Du, Huili; Cai, Xiaolin; Cui, Yanshan

2016-05-01

Arsenic (As) is a redox-active metalloid whose toxicity and mobility in soil depend on its oxidation state. Arsenite [As(III)] can be oxidized by microbes and adsorbed by minerals in the soil. However, the combined effects of these abiotic and biotic processes are not well understood. In this study, the fate of arsenic in the presence of an isolated As(III)-oxidizing bacterium (Pseudomonas sp. HN-1, 10(9) colony-forming units (CFUs)·ml(-1)) and three iron oxides (goethite, hematite, and magnetite at 1.6 g L(-1)) was determined using batch experiments. The total As adsorption by iron oxides was lower with bacteria present and was higher with iron oxides alone. The total As adsorption decreased by 78.6%, 36.0% and 79.7% for goethite, hematite and magnetite, respectively, due to the presence of bacteria. As(III) adsorbed on iron oxides could also be oxidized by Pseudomonas sp. HN-1, but the oxidation rate (1.3 μmol h(-1)) was much slower than the rate in the aqueous phase (96.2 μmol h(-1)). Therefore, the results of other studies with minerals only might overestimate the adsorptive capacity of solids in natural systems; the presence of minerals might hinder As(III) oxidation by microbes. Under aerobic conditions, in the presence of iron oxides and As(III)-oxidizing bacteria, arsenic is adsorbed onto iron oxides within the adsorption capacity, and As(V) is the primary form in the solid and aqueous phases. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of properties of iron compounds on the catalytic activity in direct coal liquefaction; Tetsu kagobutsu no keitai to sekitan ekika kassei

Energy Technology Data Exchange (ETDEWEB)

Kaneko, T.; Tazawa, K. [Mitsubishi Chemical Corp., Tokyo (Japan); Shimasaki, K. [Kobe Steel Ltd. (Japan)

1998-08-20

When considering merchandising scale of the coal liquefaction process, it is a preliminary condition that metal used for its catalyst is rich in resource volume, cheap in production cost, without pollution, and so forth, and application of cheap iron ore and ferrous compounds to disposable catalyst is desired. As liquefaction activity of the iron ore was hitherto improved by its micro crushing, its mechanical crush had a limit of about 2 {mu}m in mean particle diameter. However, together with recent crushing technique, crushers with high performance were developed, and then micro crushing by sub-micron became possible industri8ally even for iron ore. In this study, three kinds of Australian iron ores such as limonite of ferric hydroxide type iron ore, pyrite of ferrous sulfide type, and hematite of ferric oxide type were micro crushed to examine coal liquefaction activity and hydrogenation reaction activity of 1-methyl naphthalene (1-MN) and also relationship between properties and activity of catalyst for the latter before and after reaction. 11 refs., 8 figs., 5 tabs.

Maximum stellar iron core mass

Indian Academy of Sciences (India)

60, No. 3. — journal of. March 2003 physics pp. 415–422. Maximum stellar iron core mass. F W GIACOBBE. Chicago Research Center/American Air Liquide ... iron core compression due to the weight of non-ferrous matter overlying the iron cores within large .... thermal equilibrium velocities will tend to be non-relativistic.

Stabilization and functionalization of iron oxide nanoparticles for biomedical applications

Science.gov (United States)

Amstad, Esther; Textor, Marcus; Reimhult, Erik

2011-07-01

Superparamagnetic iron oxide nanoparticles (NPs) are used in a rapidly expanding number of research and practical applications in the biomedical field, including magnetic cell labeling separation and tracking, for therapeutic purposes in hyperthermia and drug delivery, and for diagnostic purposes, e.g., as contrast agents for magnetic resonance imaging. These applications require good NP stability at physiological conditions, close control over NP size and controlled surface presentation of functionalities. This review is focused on different aspects of the stability of superparamagnetic iron oxide NPs, from its practical definition to its implementation by molecular design of the dispersant shell around the iron oxide core and further on to its influence on the magnetic properties of the superparamagnetic iron oxide NPs. Special attention is given to the selection of molecular anchors for the dispersant shell, because of their importance to ensure colloidal and functional stability of sterically stabilized superparamagnetic iron oxide NPs. We further detail how dispersants have been optimized to gain close control over iron oxide NP stability, size and functionalities by independently considering the influences of anchors and the attached sterically repulsive polymer brushes. A critical evaluation of different strategies to stabilize and functionalize core-shell superparamagnetic iron oxide NPs as well as a brief introduction to characterization methods to compare those strategies is given.Superparamagnetic iron oxide nanoparticles (NPs) are used in a rapidly expanding number of research and practical applications in the biomedical field, including magnetic cell labeling separation and tracking, for therapeutic purposes in hyperthermia and drug delivery, and for diagnostic purposes, e.g., as contrast agents for magnetic resonance imaging. These applications require good NP stability at physiological conditions, close control over NP size and controlled surface

Iron from nanocompounds containing iron and zinc is highly bioavailable in rats without tissue accumulation.

Science.gov (United States)

Hilty, Florentine M; Arnold, Myrtha; Hilbe, Monika; Teleki, Alexandra; Knijnenburg, Jesper T N; Ehrensperger, Felix; Hurrell, Richard F; Pratsinis, Sotiris E; Langhans, Wolfgang; Zimmermann, Michael B

2010-05-01

Effective iron fortification of foods is difficult, because water-soluble compounds that are well absorbed, such as ferrous sulphate (FeSO(4)), often cause unacceptable changes in the colour or taste of foods. Poorly water-soluble compounds, on the other hand, cause fewer sensory changes, but are not well absorbed. Here, we show that poorly water-soluble nanosized Fe and Fe/Zn compounds (specific surface area approximately 190 m(2) g(-1)) made by scalable flame aerosol technology have in vivo iron bioavailability in rats comparable to FeSO(4) and cause less colour change in reactive food matrices than conventional iron fortificants. The addition of Zn to FePO(4) and Mg to Fe/Zn oxide increases Fe absorption from the compounds, and doping with Mg also improves their colour. After feeding rats with nanostructured iron-containing compounds, no stainable Fe was detected in their gut wall, gut-associated lymphatics or other tissues, suggesting no adverse effects. Nanosizing of poorly water-soluble Fe compounds sharply increases their absorption and nutritional value.

Iron accumulation with age, oxidative stress and functional decline.

Directory of Open Access Journals (Sweden)

Jinze Xu

2008-08-01

Full Text Available Identification of biological mediators in sarcopenia is pertinent to the development of targeted interventions to alleviate this condition. Iron is recognized as a potent pro-oxidant and a catalyst for the formation of reactive oxygen species in biological systems. It is well accepted that iron accumulates with senescence in several organs, but little is known about iron accumulation in muscle and how it may affect muscle function. In addition, it is unclear if interventions which reduced age-related loss of muscle quality, such as calorie restriction, impact iron accumulation. We investigated non-heme iron concentration, oxidative stress to nucleic acids in gastrocnemius muscle and key indices of sarcopenia (muscle mass and grip strength in male Fischer 344 X Brown Norway rats fed ad libitum (AL or a calorie restricted diet (60% of ad libitum food intake starting at 4 months of age at 8, 18, 29 and 37 months of age. Total non-heme iron levels in the gastrocnemius muscle of AL rats increased progressively with age. Between 29 and 37 months of age, the non-heme iron concentration increased by approximately 200% in AL-fed rats. Most importantly, the levels of oxidized RNA in gastrocnemius muscle of AL rats were significantly increased as well. The striking age-associated increase in non-heme iron and oxidized RNA levels and decrease in sarcopenia indices were all attenuated in the calorie restriction (CR rats. These findings strongly suggest that the age-related iron accumulation in muscle contributes to increased oxidative damage and sarcopenia, and that CR effectively attenuates these negative effects.

Chronic exposure to iron oxide, chromium oxide, and nickel oxide fumes of metal dressers in a steelworks

Science.gov (United States)

Jones, J. Graham; Warner, C. G.

1972-01-01

Graham Jones, J., and Warner, C. G. (1972).Brit. J. industr. Med.,29, 169-177. Chronic exposure to iron oxide, chromium oxide, and nickel oxide fumes of metal dressers in a steelworks. Occupational and medical histories, smoking habits, respiratory symptoms, chest radiographs, and ventilatory capacities were studied in 14 steelworkers employed as deseamers of steel ingots for periods of up to 16 years. The men were exposed for approximately five hours of each working shift to fume concentrations ranging from 1·3 to 294·1 mg/m3 made up mainly of iron oxide with varying proportions of chromium oxide and nickel oxide. Four of the men, with 14 to 16 years' exposure, showed radiological evidence of pneumoconiosis classified as ILO categories 2 or 3. Of these, two had pulmonary function within the normal range and two had measurable loss of function, moderate in one case and mild in the other. Many observers would diagnose these cases as siderosis but the authors consider that this term should be reserved for cases exposed to pure iron compounds. The correct diagnosis is mixed-dust pneumoconiosis and the loss of pulmonary function is caused by the effects of the mixture of metallic oxides. It is probable that inhalation of pure iron oxide does not cause fibrotic pulmonary changes, whereas the inhalation of iron oxide plus certain other substances obviously does. Images PMID:5021996

With regard to the fact that the microbial bio-oxidation of ferrous iron ...

African Journals Online (AJOL)

User

2011-02-28

Feb 28, 2011 ... bioleaching microbes, although most of these studies were conducted at optimum or near optimum temperature for ... activity (2.13 x10-3 h-1) obtained at pH 1.37 was more than 10 times lower than the corresponding activity at optimum ... sub-processes viz: the leaching of the sulfide mineral by ferric iron ...

Manganese and iron oxidation by fungi isolated from building stone.

Science.gov (United States)

de la Torre, M A; Gomez-Alarcon, G

1994-01-01

Acid and nonacid generating fungal strains isolated from weathered sandstone, limestone, and granite of Spanish cathedrals were assayed for their ability to oxidize iron and manganese. In general, the concentration of the different cations present in the mineral salt media directly affected Mn(IV) oxide formation, although in some cases, the addition of glucose and nitrate to the culture media was necessary. Mn(II) oxidation in acidogenic strains was greater in a medium containing the highest concentrations of glucose, nitrate, and manganese. High concentrations of Fe(II), glucose, and mineral salts were optimal for iron oxidation. Mn(IV) precipitated as oxides or hydroxides adhered to the mycelium. Most of the Fe(III) remained in solution by chelation with organic acids excreted by acidogenic strains. Other metabolites acted as Fe(III) chelators in nonacidogenic strains, although Fe(III) deposits around the mycelium were also detected. Both iron and manganese oxidation were shown to involve extracellular, hydrosoluble enzymes, with maximum specific activities during exponential growth. Strains able to oxidize manganese were also able to oxidize iron. It is concluded that iron and manganese oxidation reported in this work were biologically induced by filamentous fungi mainly by direct (enzymatic) mechanisms.

Mechanistic Study of Monodisperse Iron Oxide Nanocrystals ...

African Journals Online (AJOL)

To gain better insight into the formation of iron oxide nanocrystals from the solution phase thermal decomposition of iron (III) oleate complex, different reaction conditions including time, heating ramp, as well as concentrations of iron oleate precursor and oleic acid ligand were systematically varied and the resulting ...

Fabrication of a Functionalized Magnetic Bacterial Nanocellulose with Iron Oxide Nanoparticles.

Science.gov (United States)

Arias, Sandra L; Shetty, Akshath R; Senpan, Angana; Echeverry-Rendón, Mónica; Reece, Lisa M; Allain, Jean Paul

2016-05-26

In this study, bacterial nanocellulose (BNC) produced by the bacteria Gluconacetobacter xylinus is synthesized and impregnated in situ with iron oxide nanoparticles (IONP) (Fe3O4) to yield a magnetic bacterial nanocellulose (MBNC). The synthesis of MBNC is a precise and specifically designed multi-step process. Briefly, bacterial nanocellulose (BNC) pellicles are formed from preserved G. xylinus strain according to our experimental requirements of size and morphology. A solution of iron(III) chloride hexahydrate (FeCl3·6H2O) and iron(II) chloride tetrahydrate (FeCl2·4H2O) with a 2:1 molar ratio is prepared and diluted in deoxygenated high purity water. A BNC pellicle is then introduced in the vessel with the reactants. This mixture is stirred and heated at 80 °C in a silicon oil bath and ammonium hydroxide (14%) is then added by dropping to precipitate the ferrous ions into the BNC mesh. This last step allows forming in situ magnetite nanoparticles (Fe3O4) inside the bacterial nanocellulose mesh to confer magnetic properties to BNC pellicle. A toxicological assay was used to evaluate the biocompatibility of the BNC-IONP pellicle. Polyethylene glycol (PEG) was used to cover the IONPs in order to improve their biocompatibility. Scanning electron microscopy (SEM) images showed that the IONP were located preferentially in the fibril interlacing spaces of the BNC matrix, but some of them were also found along the BNC ribbons. Magnetic force microscope measurements performed on the MBNC detected the presence magnetic domains with high and weak intensity magnetic field, confirming the magnetic nature of the MBNC pellicle. Young's modulus values obtained in this work are also in a reasonable agreement with those reported for several blood vessels in previous studies.

Synthesis and magnetic characterizations of uniform iron oxide nanoparticles

International Nuclear Information System (INIS)

Jiang, FuYi; Li, XiaoYi; Zhu, Yuan; Tang, ZiKang

2014-01-01

Uniform iron oxide nanoparticles with a cubic shape were prepared by the decomposition of homemade iron oleate in 1-octadecene with the presence of oleic acid. The particle shape and size uniformity are sensitive to the quantity of oleic acid. XRD, HRTEM and SAED results indicated that the main phase content of as-prepared iron oxide nanoparticles is Fe 3 O 4 with an inverse spinel structure. Magnetic measurements revealed that the as-prepared iron oxide nanoparticles display a ferromagnetic behavior with a blocking temperature of 295 K. At low temperatures the magnetic anisotropy of the aligned nanoparticles caused the appearance of a hysteresis loop.

Iron(III) species formed during iron(II) oxidation and iron-core formation in bacterioferritin of Escherichia coli

International Nuclear Information System (INIS)

Hawkins, C.; Treffry, A.; Mackey, J.; Williams, J.M.; Andrews, S.C.; Guest, J.R.; Harrison, P.M.

1996-01-01

This paper describes a preliminary investigation of the mechanisms of Fe(II) oxidation and storage of Fe(III) in the bacterioferritin of Escherichia coli (EcBFR). Using Moessbauer spectroscopy to examine the initial oxidation of iron by EcBFR it is confirmed that this ferritin exhibits 'ferroxidase' activity and is shown that dimeric and monomeric iron species are produced as intermediates. The characteristics of ferroxidase activity in EcBFR is compare d with those of human H-chain ferritin (HuHF) and discuss the different Moessbauer parameters of their dimeric iron with reference to the structures of their di-metal sites. In addition, it is presented preliminary findings suggesting that after an initial 'burst', the rate of oxidation is greatly reduced, possibly due to blockage of the ferroxidase centre by bound iron. A new component, not found in HuHF and probably representing a small cluster of Fe(III) atoms, is reported

The nanophase iron mineral(s) in Mars soil

Science.gov (United States)

Banin, A.; Ben-Shlomo, T.; Margulies, L.; Blake, D. F.; Mancinelli, R. L.; Gehring, A. U.

1993-01-01

A series of surface-modified clays containing nanophase (np) iron oxide/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these "Mars-soil analogs" were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging, specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The clay acted as an effective matrix, both chemically and sterically, preventing the major part of the synthesized iron oxides from ripening, i.e., growing and developing larger crystals. The precipitated iron oxides appear as isodiametric or slightly elongated particles in the size range 1-10 nm, having large specific surface area. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (gamma-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxy mineral such as "green rust," or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable maghemite (gamma-Fe2O3) by mild heat treatment and then to nanophase hematite (alpha-Fe2O3) by extensive heat treatment. After mild heating, the iron-enriched clay became slightly magnetic, to the extent that it adheres to a hand-held magnet, as was observed with Mars soil. The chemical reactivity of the iron-enriched clays strongly resembles, and offers a plausible mechanism

Effect of excess dietary iron as ferrous sulfate and excess dietary ascorbic acid on liver zinc, copper and sulfhydryl groups and the ovary

International Nuclear Information System (INIS)

Edwards, C.H.; Adkins, J.S.; Harrison, B.

1986-01-01

Female guinea pigs of the NIH 13/N strain, weighing between 475 and 512 g, were fed diets supplemented with 50 to 2500 mg of iron per kg of diet as ferrous sulfate and 0.2 to 8.0 g of ascorbic acid per kg of diet. A significant effect was observed on tissue copper and zinc, ovary weight and liver protein sulfhydryl groups. The mean ovary weight for guinea pigs fed 2500 mg of iron was significantly less than that of animals fed 50 mg of iron, 0.045 +/- 0.012 g and 0.061 +/- 0.009 g, respectively. Liver zinc content of animals fed 2500 mg of iron and 200 mg of ascorbic acid per kg of diet was significantly less than that of animals fed 50 mg of iron and 200 mg of ascorbic acid, 16.3 +/- 3.3 μg and 19.6 +/- 1.6 μg, respectively. There was no difference in liver copper due to dietary iron, but when dietary ascorbic acid was increased to 8 g per kg of diet, there was a significant decrease (from 22.8 +/- 8.1 μg to 10.5 +/- 4.8 μg) in liver copper. Excess dietary ascorbic acid decreased ovarian zinc significantly when increased to 8 g per kg of diet, 2929 +/- 919 μg vs 1661 +/- 471 μg, respectively, when compared to the control group

Magnetic and gravity gradiometry framework for Mesoproterozoic iron oxide-apatite and iron oxide-copper-gold deposits, southeast Missouri, USA

Science.gov (United States)

McCafferty, Anne E.; Phillips, Jeffrey; Driscoll, Rhonda L.

2016-01-01

High-resolution airborne magnetic and gravity gradiometry data provide the geophysical framework for evaluating the exploration potential of hidden iron oxide deposits in Mesoproterozoic basement rocks of southeast Missouri. The data are used to calculate mineral prospectivity for iron oxide-apatite (IOA) ± rare earth element (REE) and iron oxide-copper-gold (IOCG) deposits. Results delineate the geophysical footprints of all known iron oxide deposits and reveal several previously unrecognized prospective areas. The airborne data are also inverted to three-dimensional density and magnetic susceptibility models over four concealed deposits at Pea Ridge (IOA ± REE), Boss (IOCG), Kratz Spring (IOA), and Bourbon (IOCG). The Pea Ridge susceptibility model shows a magnetic source that is vertically extensive and traceable to a depth of greater than 2 km. A smaller density source, located within the shallow Precambrian basement, is partly coincident with the magnetic source at Pea Ridge. In contrast, the Boss models show a large (625-m-wide), vertically extensive, and coincident dense and magnetic stock with shallower adjacent lobes that extend more than 2,600 m across the shallow Precambrian paleosurface. The Kratz Spring deposit appears to be a smaller volume of iron oxides and is characterized by lower density and less magnetic rock compared to the other iron deposits. A prospective area identified south of the Kratz Spring deposit shows the largest volume of coincident dense and nonmagnetic rock in the subsurface, and is interpreted as prospective for a hematite-dominant lithology that extends from the top of the Precambrian to depths exceeding 2 km. The Bourbon deposit displays a large bowl-shaped volume of coincident high density and high-magnetic susceptibility rock, and a geometry that suggests the iron mineralization is vertically restricted to the upper parts of the Precambrian basement. In order to underpin the evaluation of the prospectivity and three

Expression of Critical Sulfur- and Iron-Oxidation Genes and the Community Dynamics During Bioleaching of Chalcopyrite Concentrate by Moderate Thermophiles.

Science.gov (United States)

Zhou, Dan; Peng, Tangjian; Zhou, Hongbo; Liu, Xueduan; Gu, Guohua; Chen, Miao; Qiu, Guanzhou; Zeng, Weimin

2015-07-01

Sulfate adenylyltransferase gene and 4Fe-4S ferredoxin gene are the key genes related to sulfur and iron oxidations during bioleaching system, respectively. In order to better understand the bioleaching and microorganism synergistic mechanism in chalcopyrite bioleaching by mixed culture of moderate thermophiles, expressions of the two energy metabolism genes and community dynamics of free and attached microorganisms were investigated. Specific primers were designed for real-time quantitative PCR to study the expression of these genes. Real-time PCR results showed that sulfate adenylyltransferase gene was more highly expressed in Sulfobacillus thermosulfidooxidans than that in Acidithiobacillus caldus, and expression of 4Fe-4S ferredoxin gene was higher in Ferroplasma thermophilum than that in S. thermosulfidooxidans and Leptospirillum ferriphilum. The results indicated that in the bioleaching system of chalcopyrite concentrate, sulfur and iron oxidations were mainly performed by S. thermosulfidooxidans and F. thermophilum, respectively. The community dynamics results revealed that S. thermosulfidooxidans took up the largest proportion during the whole period, followed by F. thermophilum, A. caldus, and L. ferriphilum. The CCA analysis showed that 4Fe-4S ferredoxin gene expression was mainly affected (positively correlated) by high pH and elevated concentration of ferrous ion, while no factor was observed to prominently influence the expression of sulfate adenylyltransferase gene.

Magnetic composites based on hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides

International Nuclear Information System (INIS)

Braga, Tiago P.; Vasconcelos, Igor F.; Sasaki, Jose M.; Fabris, J.D.; Oliveira, Diana Q.L. de; Valentini, Antoninho

2010-01-01

Materials containing hybrid spheres of aluminum oxide and superparamagnetic nanoparticles of iron oxides were obtained from a chemical precursor prepared by admixing chitosan and iron and aluminum hydroxides. The oxides were first characterized with scanning electron microscopy, X-ray diffraction, and Moessbauer spectroscopy. Scanning electron microscopy micrographs showed the size distribution of the resulting spheres to be highly homogeneous. The occurrence of nano-composites containing aluminum oxides and iron oxides was confirmed from powder X-ray diffraction patterns; except for the sample with no aluminum, the superparamagnetic relaxation due to iron oxide particles were observed from Moessbauer spectra obtained at 298 and 110 K; the onset six line-spectrum collected at 20 K indicates a magnetic ordering related to the blocking relaxation effect for significant portion of small spheres in the sample with a molar ratio Al:Fe of 2:1.

Evaluation of the properties of iron oxide-filled castor oil polyurethane

Directory of Open Access Journals (Sweden)

Eleonora Mussatti

2013-02-01

Full Text Available The aim of this study was to obtain and evaluate the electrical, thermal and mechanical properties of iron oxide-filled castor oil polyurethane (PU/Fe2O3. The iron oxide used in this study was a residue derived from the steel pickling process of a Brazilian steel rolling industry. Polymeric composites with different iron oxide volume fractions (2.5, 5.0, 7.5, 10.0 and 12.5% were prepared through the casting process followed by compression molding at room temperature. The composites were analyzed by FTIR, XRD and densities, tensile strength, Young's modulus, electrical and thermal conductivities measurements. By increasing the iron oxide content, the apparent density, tensile strength, Young's modulus and electrical conductivity values of the composites were also increased. The iron oxide additions did not change significantly the value of thermal conductivity (from 0.191 W.mK-1 for PU up to 0.340 W.mK-1 for PU enriched with 12.5% v/v of iron oxide. Thus, even at the higher iron oxide concentration, the compounds as well as the pure polyurethane can be classified as thermal insulators.

Evaluation of the Properties of Iron Oxide-Filled Castor Oil Polyurethane

Directory of Open Access Journals (Sweden)

Eleonora Mussatti

2012-01-01

Full Text Available The aim of this study was to obtain and evaluate the electrical, thermal and mechanical properties of iron oxide-filled castor oil polyurethane (PU/Fe2O3. The iron oxide used in this study was a residue derived from the steel pickling process of a Brazilian steel rolling industry. Polymeric composites with different iron oxide volume fractions (2.5, 5.0, 7.5, 10.0 and 12.5% were prepared through the casting process followed by compression molding at room temperature. The composites were analyzed by FTIR, XRD and densities, tensile strength, Young's modulus, electrical and thermal conductivities measurements. By increasing the iron oxide content, the apparent density, tensile strength, Young's modulus and electrical conductivity values of the composites were also increased. The iron oxide additions did not change significantly the value of thermal conductivity (from 0.191 W.mK-1 for PU up to 0.340 W.mK-1 for PU enriched with 12.5% v/v of iron oxide. Thus, even at the higher iron oxide concentration, the compounds as well as the pure polyurethane can be classified as thermal insulators.

High pressure Moessbauer spectroscopy of perovskite iron oxide

CERN Document Server

Nasu, S; Morimoto, S; Kawakami, T; Kuzushita, K; Takano, M

2003-01-01

High-pressure sup 5 sup 7 Fe Moessbauer spectroscopy using a diamond anvil cell has been performed for perovskite iron oxides SrFeO sub 3 , CaFeO sub 3 and La sub 1 sub / sub 3 Sr sub 2 sub / sub 3 O sub 3. The charge states and the magnetic dependency to pressure were determined. Pressure magnetic phase diagrams of these perovskite iron oxides are determined up to about 70 GPa. To be clear the magnetic ordered state, they are measured up to 7.8 T external magnetic fields at 4.5K. The phase transition of these perovskite oxides to ferromagnetisms with high magnetic ordered temperature is observed. In higher pressure, high spin-low spin transition of oxides besides CaFeO sub 3 is generated. The feature of Moessbauer spectroscopy, perovskite iron oxide and Moessbauer spectroscopy under high pressure are explained. (S.Y.)

Comparative evaluation of nephrotoxicity and management by macrophages of intravenous pharmaceutical iron formulations.

Directory of Open Access Journals (Sweden)

James R Connor

Full Text Available There is a significant clinical need for effective treatment of iron deficiency. A number of compounds that can be administered intravenously have been developed. This study examines how the compounds are handled by macrophages and their relative potential to provoke oxidative stress.Human kidney (HK-2 cells, rat peritoneal macrophages and renal cortical homogenates were exposed to pharmaceutical iron preparations. Analyses were performed for indices of oxidative stress and cell integrity. In addition, in macrophages, iron uptake and release and cytokine secretion was monitored.HK-2 cell viability was decreased by iron isomaltoside and ferumoxytol and all compounds induced lipid peroxidation. In the renal cortical homogenates, lipid peroxidation occurred at lowest concentrations with ferric carboxymaltose, iron dextran, iron sucrose and sodium ferric gluconate. In the macrophages, iron sucrose caused loss of cell viability. Iron uptake was highest for ferumoxytol and iron isomaltoside and lowest for iron sucrose and sodium ferric gluconate. Iron was released as secretion of ferritin or as ferrous iron via ferroportin. The latter was blocked by hepcidin. Exposure to ferric carboxymaltose and iron dextran resulted in release of tumor necrosis factor α.Exposure to iron compounds increased cell stress but was tissue and dose dependent. There was a clear difference in the handling of iron from the different compounds by macrophages that suggests in vivo responses may differ.

Evaluation of iron transport from ferrous glycinate liposomes using ...

African Journals Online (AJOL)

2017-09-03

Sep 3, 2017 ... Insufficient dietary intake and low iron bio- availability in foods ... pared with common iron supplements, iron liposomes can obviously ... to inhibit iron absorption in humans and in cell culture models11. ..... ical nutrition issues. The effects of .... of approximately 2-100 nm could play an active role in mediating ...

X-Ray Photoelectron Spectroscopic Characterization of Iron Oxide Nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Radu, T., E-mail: Teodora.Radu@itim-cj.ro [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293, Cluj Napoca (Romania); Iacovita, C. [Department of Pharmaceutical Physics-Biophysics, Faculty of Pharmacy, “Iuliu Hatieganu” University of Medicine and Pharmacy, 400349, Cluj-Napoca (Romania); Benea, D. [Faculty of Physics, Babes Bolyai University, 400271, Cluj-Napoca (Romania); Turcu, R. [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat Street, 400293, Cluj Napoca (Romania)

2017-05-31

Highlights: • Characterization of three types of iron oxides magnetic nanoparticles. • A correlation between valence band XPS and the degree of iron oxidation is proposed. • Theoretical contributions of Fe in tetragonal and octahedral environment are shown. - Abstract: We report X-ray photoelectron spectroscopy (XPS) results on iron oxide magnetic nanoparticle (Fe{sub 3}O{sub 4}) synthesized using solvothermal reduction in the presence of polyethylene glycol. The magnetite obtained was employed as precursor for the synthesis of γ-Fe{sub 2}O{sub 3} (by oxygen dissociation) which in turn was transformed into α-Fe{sub 2}O{sub 3}. We confirmed the magnetite, maghemite and hematite structure by Fourier Transformed Spectroscopy (FTIR) and X-ray diffraction (XRD). The analysis of the XPS core level and valence band (VB) photoemission spectra for all investigated samples is discussed in terms of the degree of iron oxidation. This is of fundamental importance to better understand the electronic structure of the obtained iron oxide nanoparticles in order to control and improve their quality for specific biomedical applications. Moreover, theoretical band structure calculations are performed for magnetite and the separate contributions of Fe in tetragonal and octahedral environment are shown.

Near-IR MCD of the nonheme ferrous active site in naphthalene 1,2-dioxygenase: correlation to crystallography and structural insight into the mechanism of Rieske dioxygenases.

Science.gov (United States)

Ohta, Takehiro; Chakrabarty, Sarmistha; Lipscomb, John D; Solomon, Edward I

2008-02-06

Near-IR MCD and variable temperature, variable field (VTVH) MCD have been applied to naphthalene 1,2-dioxygenase (NDO) to describe the coordination geometry and electronic structure of the mononuclear nonheme ferrous catalytic site in the resting and substrate-bound forms with the Rieske 2Fe2S cluster oxidized and reduced. The structural results are correlated with the crystallographic studies of NDO and other related Rieske nonheme iron oxygenases to develop molecular level insights into the structure/function correlation for this class of enzymes. The MCD data for resting NDO with the Rieske center oxidized indicate the presence of a six-coordinate high-spin ferrous site with a weak axial ligand which becomes more tightly coordinated when the Rieske center is reduced. Binding of naphthalene to resting NDO (Rieske oxidized and reduced) converts the six-coordinate sites into five-coordinate (5c) sites with elimination of a water ligand. In the Rieske oxidized form the 5c sites are square pyramidal but transform to a 1:2 mixture of trigonal bipyramial/square pyramidal sites when the Rieske center is reduced. Thus the geometric and electronic structure of the catalytic site in the presence of substrate can be significantly affected by the redox state of the Rieske center. The catalytic ferrous site is primed for the O2 reaction when substrate is bound in the active site in the presence of the reduced Rieske site. These structural changes ensure that two electrons and the substrate are present before the binding and activation of O2, which avoids the uncontrolled formation and release of reactive oxygen species.

Characterization of arsenic resistant and arsenopyrite oxidizing Acidithiobacillus ferrooxidans from Hutti gold leachate and effluents.

Science.gov (United States)

Dave, Shailesh R; Gupta, Kajal H; Tipre, Devayani R

2008-11-01

Four arsenic resistant ferrous oxidizers were isolated from Hutti Gold Mine Ltd. (HGML) samples. Characterization of these isolates was done using conventional microbiological, biochemical and molecular methods. The ferrous oxidation rates with these isolates were 16, 48, 34 and 34 mg L(-1)h(-1) and 15, 47, 34 and 32 mg L(-1)h(-1) in absence and presence of 20 mM of arsenite (As3+) respectively. Except isolate HGM 8, other three isolates showed 2.9-6.3% inhibition due to the presence of 20 mM arsenite. Isolate HGM 8 was able to grow in presence of 14.7 g L(-1) of arsenite, with 25.77 mg L(-1)h(-1) ferrous oxidation rate. All the four isolates were able to oxidize iron and arsenopyrite from 20 g L(-1) and 40 g L(-1) refractory gold ore and 20 g L(-1) refractory gold concentrate. Once the growth was established pH adjustment was not needed inspite of ferrous oxidation, which could be due to concurrent oxidation of pyrite. Isolate HGM 8 showed the final cell count of as high as 1.12 x 10(8) cells mL(-1) in 40 g L(-1) refractory gold ore. The isolates were grouped into one haplotypes by amplified ribosomal DNA restriction analysis (ARDRA). The phylogenetic position of HGM 8 was determined by 16S rDNA sequencing. It was identified as Acidithiobacillus ferrooxidans and strain name was given as SRHGM 1.

Anoxic and Oxic Oxidation of Rocks Containing Fe(II)Mg-Silicates and Fe(II)-Monosulfides as Source of Fe(III)-Minerals and Hydrogen. Geobiotropy.

Science.gov (United States)

Bassez, Marie-Paule

2017-12-01

In this article, anoxic and oxic hydrolyses of rocks containing Fe (II) Mg-silicates and Fe (II)-monosulfides are analyzed at 25 °C and 250-350 °C. A table of the products is drawn. It is shown that magnetite and hydrogen can be produced during low-temperature (25 °C) anoxic hydrolysis/oxidation of ferrous silicates and during high-temperature (250 °C) anoxic hydrolysis/oxidation of ferrous monosulfides. The high-T (350 °C) anoxic hydrolysis of ferrous silicates leads mainly to ferric oxides/hydroxides such as the hydroxide ferric trihydroxide, the oxide hydroxide goethite/lepidocrocite and the oxide hematite, and to Fe(III)-phyllosilicates. Magnetite is not a primary product. While the low-T (25 °C) anoxic hydrolysis of ferrous monosulfides leads to pyrite. Thermodynamic functions are calculated for elementary reactions of hydrolysis and carbonation of olivine and pyroxene and E-pH diagrams are analyzed. It is shown that the hydrolysis of the iron endmember is endothermic and can proceed within the exothermic hydrolysis of the magnesium endmember and also within the exothermic reactions of carbonations. The distinction between three products of the iron hydrolysis, magnetite, goethite and hematite is determined with E-pH diagrams. The hydrolysis/oxidation of the sulfides mackinawite/troilite/pyrrhotite is highly endothermic but can proceed within the heat produced by the exothermic hydrolyses and carbonations of ferromagnesian silicates and also by other sources such as magma, hydrothermal sources, impacts. These theoretical results are confirmed by the products observed in several related laboratory experiments. The case of radiolyzed water is studied. It is shown that magnetite and ferric oxides/hydroxides such as ferric trihydroxide, goethite/lepidocrocite and hematite are formed in oxic hydrolysis of ferromagnesian silicates at 25 °C and 350 °C. Oxic oxidation of ferrous monosulfides at 25 °C leads mainly to pyrite and ferric oxides/hydroxides such as

Iron oxide redox chemistry and nuclear fuel disposal

International Nuclear Information System (INIS)

Jobe, D.J.; Lemire, R.J.; Taylor, P.

1997-04-01

Solubility and stability data for iron (III) oxides and aqueous Fe(II) and Fe(III) species are reviewed, and selected values are used to calculate potential-pH diagrams for the iron system at temperatures of 25 and 100 deg C, chloride activities {C1 - } = 10 -2 and 1 mol/kg, total carbonate activity {C T } = 10 -3 mol/kg, and iron(III) oxide/oxyhydroxide solubility products (25 deg C values) K sp = {Fe 3+ }{OH - } 3 = 10 -38.5 , 10 -40 and 10 -42 . The temperatures and anion concentrations bracket the range of conditions expected in a Canadian nuclear fuel waste disposal vault. The three solubility products represent a conservative upper limit, a most probable value, and a minimum credible value, respectively, for the iron oxides likely to be important in controlling redox conditions in a disposal vault for CANDU nuclear reactor fuel. Only in the first of these three cases do the calculated redox potentials significantly exceed values under which oxidative dissolution of the fuel may occur. (author)

Ferrite grade iron oxides from ore rejects

Indian Academy of Sciences (India)

Iron oxyhydroxides and hydroxides were synthesized from chemically beneficiated high SiO2/Al2O3 low-grade iron ore (57.49% Fe2O3) rejects and heated to get iron oxides of 96–99.73% purity. The infrared band positions, isothermal weight loss and thermogravimetric and chemical analysis established the chemical ...

Magnetization measurements and XMCD studies on ion irradiated iron oxide and core-shell iron/iron-oxide nanomaterials

Energy Technology Data Exchange (ETDEWEB)

Kaur, Maninder; Qiang, You; Jiang, Weilin; Pearce, Carolyn; McCloy, John S.

2014-12-02

Magnetite (Fe3O4) and core-shell iron/iron-oxide (Fe/Fe3O4) nanomaterials prepared by a cluster deposition system were irradiated with 5.5 MeV Si2+ ions and the structures determined by x-ray diffraction as consisting of 100% magnetite and 36/64 wt% Fe/FeO, respectively. However, x-ray magnetic circular dichroism (XMCD) indicates similar surfaces in the two samples, slightly oxidized and so having more Fe3+ than the expected magnetite structure, with XMCD intensity much lower for the irradiated core-shell samples indicating weaker magnetism. X-ray absorption spectroscopy (XAS) data lack the signature for FeO, but the irradiated core-shell system consists of Fe-cores with ~13 nm of separating oxide crystallite, so it is likely that FeO exists deeper than the probe depth of the XAS (~5 nm). Exchange bias (Hex) for both samples becomes increasingly negative as temperature is lowered, but the irradiated Fe3O4 sample shows greater sensitivity of cooling field on Hex. Loop asymmetries and Hex sensitivities of the irradiated Fe3O4 sample are due to interfaces and interactions between grains which were not present in samples before irradiation as well as surface oxidation. Asymmetries in the hysteresis curves of the irradiated core/shell sample are related to the reversal mechanism of the antiferromagnetic FeO and possibly some near surface oxidation.

Amyloid fibril systems reduce, stabilize and deliver bioavailable nanosized iron

Science.gov (United States)

Shen, Yi; Posavec, Lidija; Bolisetty, Sreenath; Hilty, Florentine M.; Nyström, Gustav; Kohlbrecher, Joachim; Hilbe, Monika; Rossi, Antonella; Baumgartner, Jeannine; Zimmermann, Michael B.; Mezzenga, Raffaele

2017-07-01

Iron-deficiency anaemia (IDA) is a major global public health problem. A sustainable and cost-effective strategy to reduce IDA is iron fortification of foods, but the most bioavailable fortificants cause adverse organoleptic changes in foods. Iron nanoparticles are a promising solution in food matrices, although their tendency to oxidize and rapidly aggregate in solution severely limits their use in fortification. Amyloid fibrils are protein aggregates initially known for their association with neurodegenerative disorders, but recently described in the context of biological functions in living organisms and emerging as unique biomaterial building blocks. Here, we show an original application for these protein fibrils as efficient carriers for iron fortification. We use biodegradable amyloid fibrils from β-lactoglobulin, an inexpensive milk protein with natural reducing effects, as anti-oxidizing nanocarriers and colloidal stabilizers for iron nanoparticles. The resulting hybrid material forms a stable protein-iron colloidal dispersion that undergoes rapid dissolution and releases iron ions during acidic and enzymatic in vitro digestion. Importantly, this hybrid shows high in vivo iron bioavailability, equivalent to ferrous sulfate in haemoglobin-repletion and stable-isotope studies in rats, but with reduced organoleptic changes in foods. Feeding the rats with these hybrid materials did not result in abnormal iron accumulation in any organs, or changes in whole blood glutathione concentrations, inferring their primary safety. Therefore, these iron-amyloid fibril hybrids emerge as novel, highly effective delivery systems for iron in both solid and liquid matrices.

Ultrafine ferromagnetic iron oxide nanoparticles: Facile synthesis by low temperature decomposition of iron glycerolate

Energy Technology Data Exchange (ETDEWEB)

Bartůněk, Vilém, E-mail: vilem.bartunek@vscht.cz [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic); Průcha, David [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic); Švecová, Marie [Department of Analytical Chemistry, Faculty of Chemical Engineering, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic); Ulbrich, Pavel [Department of Biochemistry and Microbiology, Faculty of Food and Biochemical Technology, University of Chemistry and Technology, Technická 3, 166 28 Prague 6 (Czech Republic); Huber, Štěpán; Sedmidubský, David; Jankovský, Ondřej [Department of Inorganic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Technická 5, 166 28 Prague 6 (Czech Republic)

2016-09-01

We synthesized dark colored ultrafine – sub 10 nm iron oxide nanoparticles by a facile and low temperature process based on thermal decomposition of an affordable precursor – iron glycerolate. Simultaneous thermal analysis (STA) was used to study the thermal behaviour during the decomposition. The iron glycerolate was thoroughly analysed by various methods. The size of the iron nanoparticles was determined from XRD patterns and by transmission electron microscopy (TEM) and their composition has been confirmed by XPS. Magnetic properties of the nanoparticles were studied by vibrating sample magnetometry. The prepared single phase material exhibiting ferromagnetic properties is usable in a wide range of applications and may be suitable even for large scale industrial applications. - Highlights: • Iron glycerolate prepared and characterised. • Iron oxide nanoparticles prepared by thermal decomposition of iron glycerolate. • STA used to study the decomposition. • Products characterised by XRD, XPS, FT-IR, SEM and TEM. • Magnetic behaviour of monophasic samples determined.

Iron oxide and gold nanoparticles in cancer therapy

Energy Technology Data Exchange (ETDEWEB)

Gotman, Irena, E-mail: gotman@technion.ac.il; Gutmanas, Elazar Y., E-mail: gutmanas@technion.ac.il [Department of Materials Science and Engineering, Technion-Israel Institute of Technology, Haifa, 32000 Israel (Israel); Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Psakhie, Sergey G. [Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Lozhkomoev, Aleksandr S. [Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

2016-08-02

Continuous research activities in the field of nanomedicine in the past decade have, to a great extent, been focused on nanoparticle technologies for cancer therapy. Gold and iron oxide nanoparticles (NP) are two of the most studied inorganic nanomaterials due to their unique optical and magnetic properties. Both types of NPs are emerging as promising systems for anti-tumor drug delivery and for nanoparticle-mediated thermal therapy of cancer. In thermal therapy, localized heating inside tumors or in proximity of tumor cells can be induced, for example, with Au NPs by radiofrequency ablation heating or conversion of photon energy (photothermal therapy) and in iron oxide magnetic NPs by heat generation through relaxation in an alternating magnetic field (magnetic hyperthermia). Furthermore, the superparamagnetic properties of iron oxide nanoparticles have led to their use as potent MRI (magnetic resonance imaging) contrast agents. Surface modification/coating can produce NPs with tailored and desired properties, such as enhanced blood circulation time, stability, biocompatibility and water solubility. To target nanoparticles to specific tumor cells, NPs should be conjugated with targeting moieties on the surface which bind to receptors or other molecular structures on the cell surface. The article presents several approaches to enhancing the specificity of Au and iron oxide nanoparticles for tumor tissue by appropriate surface modification/functionalization, as well as the effect of these treatments on the saturation magnetization value of iron oxide NPs. The use of other nanoparticles and nanostructures in cancer treatment is also briefly reviewed.

Inactivation of 1-aminocyclopropane-1-carboxylate oxidase involves oxidative modifications.

Science.gov (United States)

Barlow, J N; Zhang, Z; John, P; Baldwin, J E; Schofield, C J

1997-03-25

1-Aminocyclopropane-1-carboxylate (ACC) oxidase catalyzes the final step in the biosynthesis of the plant signaling molecule ethylene. It is a member of the ferrous iron dependent family of oxidases and dioxygenases and is unusual in that it displays a very short half-life under catalytic conditions, typically less than 20 min, and a requirement for CO2 as an activator. The rates of inactivation of purified, recombinant ACC oxidase from tomato under various combinations of substrates and cofactors were measured. Inactivation was relatively slow in the presence of buffer alone (t1/2 > 1 h), but fast in the presence of ferrous iron and ascorbate (t1/2 approximately 10 min). The rate of iron/ascorbate-mediated inactivation was increased by the addition of ACC, unaffected by the addition of CO2 at saturation (supplied as bicarbonate) but decreased by the addition of catalase or ACC + CO2 at saturation (supplied as bicarbonate). Iron/ascorbate-mediated inactivation was accompanied by partial proteolysis as observed by SDS-PAGE analysis. The fragmentation pattern was altered when ACC was also included, suggesting that ACC can bind to ACC oxidase in the absence of bicarbonate. N-terminal sequencing of fragments resulted in identification of an internal cleavage site which we propose is proximate to active-site bound iron. Thus, ACC oxidase inactivates via relatively slow partial unfolding of the catalytically active conformation, oxidative damage mediated via hydrogen peroxide which is catalase protectable and oxidative damage to the active site which results in partial proteolysis and is not catalase protectable.

Correlation of flow accelerated corrosion rate with iron solubility

International Nuclear Information System (INIS)

Fujiwara, K.; Domae, M.; Yoneda, K.; Inada, F.; Ohira, T.; Hisamune, K.; Takiguchi, H.

2009-01-01

Flow Accelerated Corrosion (FAC) of carbon steel is one of the most important subjects in coolant systems of power plants. FAC is influenced by material, flow condition, temperature, and water chemistry. It is considered that solubility is the most important factor to determine the effect of water chemistry on FAC. In the present study, effect of specific oxide on FAC rate was studied from the thermodynamic solubility of iron. The effects of temperature and pH on the iron solubility were evaluated by taking into consideration hydrolysis reactions of ferrous iron, dissolution equilibria of Fe 3 O 4 , FeO, and Fe(OH) 2 , and charge balance. The correlation between the iron solubility and FAC behavior was evaluated by using the normalized mass transfer coefficient. It is clarified that the product of iron solubility equilibrated with Fe 3 O 4 and normalized mass transfer coefficient can explain the temperature and pH dependence of FAC. These results indicate presence of magnetite on the surface of carbon steel. Diffusion of iron from the saturated layer determines the FAC rate from water chemistry aspect. (author)

Acid monolayer functionalized iron oxide nanoparticle catalysts

Science.gov (United States)

Ikenberry, Myles

Superparamagnetic iron oxide nanoparticle functionalization is an area of intensely active research, with applications across disciplines such as biomedical science and heterogeneous catalysis. This work demonstrates the functionalization of iron oxide nanoparticles with a quasi-monolayer of 11-sulfoundecanoic acid, 10-phosphono-1-decanesulfonic acid, and 11-aminoundecanoic acid. The carboxylic and phosphonic moieties form bonds to the iron oxide particle core, while the sulfonic acid groups face outward where they are available for catalysis. The particles were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), potentiometric titration, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectrometry (XPS), and dynamic light scattering (DLS). The sulfonic acid functionalized particles were used to catalyze the hydrolysis of sucrose at 80° and starch at 130°, showing a higher activity per acid site than the traditional solid acid catalyst Amberlyst-15, and comparing well against results reported in the literature for sulfonic acid functionalized mesoporous silicas. In sucrose catalysis reactions, the phosphonic-sulfonic nanoparticles (PSNPs) were seen to be incompletely recovered by an external magnetic field, while the carboxylic-sulfonic nanoparticles (CSNPs) showed a trend of increasing activity over the first four recycle runs. Between the two sulfonic ligands, the phosphonates produced a more tightly packed monolayer, which corresponded to a higher sulfonic acid loading, lower agglomeration, lower recoverability through application of an external magnetic field, and higher activity per acid site for the hydrolysis of starch. Functionalizations with 11-aminoundecanoic acid resulted in some amine groups binding to the surfaces of iron oxide nanoparticles. This amine binding is commonly ignored in iron oxide

Monomeric Yeast Frataxin is an Iron-Binding Protein

International Nuclear Information System (INIS)

Cook, J.; Bencze, K.; Jankovic, A.; Crater, A.; Busch, C.; Bradley, P.; Stemmler, A.; Spaller, M.; Stemmler, T.

2006-01-01

Friedreich's ataxia, an autosomal cardio- and neurodegenerative disorder that affects 1 in 50 000 humans, is caused by decreased levels of the protein frataxin. Although frataxin is nuclear-encoded, it is targeted to the mitochondrial matrix and necessary for proper regulation of cellular iron homeostasis. Frataxin is required for the cellular production of both heme and iron-sulfur (Fe-S) clusters. Monomeric frataxin binds with high affinity to ferrochelatase, the enzyme involved in iron insertion into porphyrin during heme production. Monomeric frataxin also binds to Isu, the scaffold protein required for assembly of Fe-S cluster intermediates. These processes (heme and Fe-S cluster assembly) share requirements for iron, suggesting that monomeric frataxin might function as the common iron donor. To provide a molecular basis to better understand frataxin's function, we have characterized the binding properties and metal-site structure of ferrous iron bound to monomeric yeast frataxin. Yeast frataxin is stable as an iron-loaded monomer, and the protein can bind two ferrous iron atoms with micromolar binding affinity. Frataxin amino acids affected by the presence of iron are localized within conserved acidic patches located on the surfaces of both helix-1 and strand-1. Under anaerobic conditions, bound metal is stable in the high-spin ferrous state. The metal-ligand coordination geometry of both metal-binding sites is consistent with a six-coordinate iron-(oxygen/nitrogen) based ligand geometry, surely constructed in part from carboxylate and possibly imidazole side chains coming from residues within these conserved acidic patches on the protein. On the basis of our results, we have developed a model for how we believe yeast frataxin interacts with iron

Synthesis and applications of nano-structured iron oxides/hydroxides

African Journals Online (AJOL)

... in numerous synthesis processes. This review outlines the work being carried out on synthesis of iron oxides in nano form and their various applications. Keywords: nano iron oxides, synthesis, catalysts, magnetic properties, biomedical application. International Journal of Engineering, Science and Technology, Vol. 2, No.

Effects of chloride ions on corrosion of ductile iron and carbon steel in soil environments.

Science.gov (United States)

Song, Yarong; Jiang, Guangming; Chen, Ying; Zhao, Peng; Tian, Yimei

2017-07-31

Chloride is reported to play a significant role in corrosion reactions, products and kinetics of ferrous metals. To enhance the understanding of the effects of soil environments, especially the saline soils with high levels of chloride, on the corrosion of ductile iron and carbon steel, a 3-month corrosion test was carried out by exposing ferrous metals to soils of six chloride concentrations. The surface morphology, rust compositions and corrosion kinetics were comprehensively studied by visual observation, scanning electron microscopy (SEM), X-Ray diffraction (XRD), weight loss, pit depth measurement, linear polarization and electrochemical impedance spectroscopy (EIS) measurements. It showed that chloride ions influenced the characteristics and compositions of rust layers by diverting and participating in corrosion reactions. α-FeOOH, γ-FeOOH and iron oxides were major corrosion products, while β-Fe 8 O 8 (OH) 8 Cl 1.35 rather than β-FeOOH was formed when high chloride concentrations were provided. Chloride also suppressed the decreasing of corrosion rates, whereas increased the difficulty in the diffusion process by thickening the rust layers and transforming the rust compositions. Carbon steel is more susceptible to chloride attacks than ductile iron. The corrosion kinetics of ductile iron and carbon steel corresponded with the probabilistic and bilinear model respectively.

Diverse arsenic- and iron-cycling microbial communities in arsenic-contaminated aquifers used for drinking water in Bangladesh.

Science.gov (United States)

Hassan, Zahid; Sultana, Munawar; van Breukelen, Boris M; Khan, Sirajul I; Röling, Wilfred F M

2015-04-01

Subsurface removal of arsenic by injection with oxygenated groundwater has been proposed as a viable technology for obtaining 'safe' drinking water in Bangladesh. While the oxidation of ferrous iron to solid ferric iron minerals, to which arsenic adsorbs, is assumed to be driven by abiotic reactions, metal-cycling microorganisms may potentially affect arsenic removal. A cultivation-independent survey covering 24 drinking water wells in several geographical regions in Bangladesh was conducted to obtain information on microbial community structure and diversity in general, and on specific functional groups capable of the oxidation or reduction of arsenic or iron. Each functional group, targeted by either group-specific 16S rRNA or functional gene amplification, occurred in at least 79% of investigated samples. Putative arsenate reducers and iron-oxidizing Gallionellaceae were present at low diversity, while more variation in potentially arsenite-oxidizing microorganisms and iron-reducing Desulfuromonadales was revealed within and between samples. Relations between community composition on the one hand and hydrochemistry on the other hand were in general not evident, apart from an impact of salinity on iron-cycling microorganisms. Our data suggest widespread potential for a positive contribution of arsenite and iron oxidizers to arsenic removal upon injection with oxygenated water, but also indicate a potential risk for arsenic re-mobilization by anaerobic arsenate and iron reducers once injection is halted. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Progress in electrochemical synthesis of magnetic iron oxide nanoparticles

International Nuclear Information System (INIS)

Ramimoghadam, Donya; Bagheri, Samira; Hamid, Sharifah Bee Abd

2014-01-01

Recently, magnetic iron oxide particles have been emerged as significant nanomaterials due to its extensive range of application in various fields. In this regard, synthesis of iron oxide nanoparticles with desirable properties and high potential applications are greatly demanded. Therefore, investigation on different iron oxide phases and their magnetic properties along with various commonly used synthetic techniques are remarked and thoroughly described in this review. Electrochemical synthesis as a newfound method with unique advantages is elaborated, followed by design approaches and key parameters to control the properties of the iron oxide nanoparticles. Additionally, since the dispersion of iron oxide nanoparticles is as important as its preparation, surface modification issue has been a serious challenge which is comprehensively discussed using different surfactants. Despite the advantages of the electrochemical synthesis method, this technique has been poorly studied and requires deep investigations on effectual parameters such as current density, pH, electrolyte concentration etc. - Highlights: • IONPs are applied in chemical industries, medicine, magnetic storage etc. • Electrochemical synthesis (EC) is convenient, eco-friendly, selective and low-cost. • EC key factors are current density, pH, electrolyte concentration, electrode type. • Organic, inorganic and biological materials can be used to modify IONPs’ surface. • The physicochemical properties of IONPs can be controlled by adding surfactants

Selectivity and Activity of Iron Molybdate Catalysts in Oxidation of Methanol

Directory of Open Access Journals (Sweden)

Khalid Khazzal Hummadi

2009-06-01

Full Text Available The selectivity and activity of iron molybdate catalysts prepared by different methods are compared with those of a commercial catalyst in the oxidation of methanol to formaldehyde in a continuous tubular bed reactor at 200-350 oC (473-623 oK, 10 atm (1013 kPa, with a methanol-oxygen mixture fixed at 5.5% by volume methanol: air ratio. The iron(III molybdate catalyst prepared by co-precipitation and filtration had a selectivity towards formaldehyde in methanol oxidation comparable with a commercial catalyst; maximum selectivity (82.3% was obtained at 573oK when the conversion was 59.7%. Catalysts prepared by reacting iron (III and molybdate by kneading or precipitation followed by evaporation, omitting a filtration stage, were less active and less selective. The selectivity-activity relationships of these catalysts as a function of temperature were discussed in relation to the method of preparation, surface areas and composition. By combing this catalytic data with data from the patent literature we demonstrate a synergy between iron and molybdenum in regard to methanol oxidation to formaldehyde; the optimum composition corresponded to an iron mole fraction 0.2-0.3. The selectivity to formaldehyde was practically constant up to an iron mole fraction 0.3 and then decreased at higher iron concentrations. The iron component can be regarded as the activity promoter. The iron molybdate catalysts can thus be related to other two-component MoO3-based selective oxidation catalysts, e.g. bismuth and cobalt molybdates. The iron oxide functions as a relatively basic oxide abstracting, in the rate-controlling step, a proton from the methyl of a bound methoxy group of chemisorbed methanol. It was proposed that a crucial feature of the sought after iron(III molybdate catalyst is the presence of -O-Mo-O-Fe-O-Mo-O- groups as found in the compound Fe2(MoO43 and for Fe3+ well dispersed in MoO3 generally. At the higher iron(III concentrations the loss of

KINETICS OF THE OXIDATION OF FERROUS CHELATES OF EDTA AND HEDTA IN AQUEOUS-SOLUTION

NARCIS (Netherlands)

WUBS, HJ; BEENACKERS, AACM

1993-01-01

The kinetics of the reaction of oxygen with ferrous chelates of EDTA and HEDTA was studied in a stirred cell reactor under industrial conditions. The temperature was varied from 20 to 60-degrees-C and the concentration of the ferrous chelate ranged from 0 to 100 mol/m3. The initial pH was 7.5. Under

Magnetic behavior of iron oxide nanoparticle-biomolecule assembly

International Nuclear Information System (INIS)

Kim, Taegyun; Reis, Lynn; Rajan, Krishna; Shima, Mutsuhiro

2005-01-01

Iron oxide nanoparticles of 8-20 nm in size were investigated as an assembly with biomolecules synthesized in an aqueous solution. The magnetic behavior of the biomolecule-nanoparticles assembly depends sensitively on the morphology and hence the distribution of the nanoparticles, where the dipole coupling between the nanoparticles governs the overall magnetic behavior. In assemblies of iron oxide nanoparticles with trypsin, we observe a formation of unusual self-alignment of nanoparticles within trypsin molecules. In such an assembly structure, the magnetic particles tend to exhibit a lower spin-glass transition temperature than as-synthesized bare iron oxide nanoparticles probably due to reduced interparticle couplings within the molecular matrix. The observed self-alignment of nanoparticles in biomolecules may be a useful approach for directed nanoparticles assembly

Iron oxide nanotubes synthesized via template-based electrodeposition

Science.gov (United States)

Lim, Jin-Hee; Min, Seong-Gi; Malkinski, Leszek; Wiley, John B.

2014-04-01

Considerable effort has been invested in the development of synthetic methods for the preparation iron oxide nanostructures for applications in nanotechnology. While a variety of structures have been reported, only a few studies have focused on iron oxide nanotubes. Here, we present details on the synthesis and characterization of iron oxide nanotubes along with a proposed mechanism for FeOOH tube formation. The FeOOH nanotubes, fabricated via a template-based electrodeposition method, are found to exhibit a unique inner-surface. Heat treatment of these tubes under oxidizing or reducing atmospheres can produce either hematite (α-Fe2O3) or magnetite (Fe3O4) structures, respectively. Hematite nanotubes are composed of small nanoparticles less than 20 nm in diameter and the magnetization curves and FC-ZFC curves show superparamagnetic properties without the Morin transition. In the case of magnetite nanotubes, which consist of slightly larger nanoparticles, magnetization curves show ferromagnetism with weak coercivity at room temperature, while FC-ZFC curves exhibit the Verwey transition at 125 K.Considerable effort has been invested in the development of synthetic methods for the preparation iron oxide nanostructures for applications in nanotechnology. While a variety of structures have been reported, only a few studies have focused on iron oxide nanotubes. Here, we present details on the synthesis and characterization of iron oxide nanotubes along with a proposed mechanism for FeOOH tube formation. The FeOOH nanotubes, fabricated via a template-based electrodeposition method, are found to exhibit a unique inner-surface. Heat treatment of these tubes under oxidizing or reducing atmospheres can produce either hematite (α-Fe2O3) or magnetite (Fe3O4) structures, respectively. Hematite nanotubes are composed of small nanoparticles less than 20 nm in diameter and the magnetization curves and FC-ZFC curves show superparamagnetic properties without the Morin transition

High rate flame synthesis of highly crystalline iron oxide nanorods

International Nuclear Information System (INIS)

Merchan-Merchan, W; Taylor, A M; Saveliev, A V

2008-01-01

Single-step flame synthesis of iron oxide nanorods is performed using iron probes inserted into an opposed-flow methane oxy-flame. The high temperature reacting environment of the flame tends to convert elemental iron into a high density layer of iron oxide nanorods. The diameters of the iron oxide nanorods vary from 10 to 100 nm with a typical length of a few microns. The structural characterization performed shows that nanorods possess a highly ordered crystalline structure with parameters corresponding to cubic magnetite (Fe 3 O 4 ) with the [100] direction oriented along the nanorod axis. Structural variations of straight nanorods such as bends, and T-branched and Y-branched shapes are frequently observed within the nanomaterials formed, opening pathways for synthesis of multidimensional, interconnected networks

Adsorption of poly(vinyl formamide-co-vinyl amine) (PVFA-co-PVAm) polymers on zinc, zinc oxide, iron, and iron oxide surfaces.

Science.gov (United States)

Seifert, Susan; Simon, Frank; Baumann, Giesela; Hietschold, Michael; Seifert, Andreas; Spange, Stefan

2011-12-06

The adsorption of poly(vinyl formamide) (PVFA) and the statistic copolymers poly(vinyl formamide-co-vinyl amine) (PVFA-co-PVAm) onto zinc and iron metal particles as well as their oxides was investigated. The adsorbates were characterized by means of XPS, DRIFT spectroscopy, wet chemical analysis, and solvatochromic probes. Dicyano-bis-(1,10-phenanthroline)-iron(II) (1), 3-(4-amino-3-methylphenyl)-7-phenyl-benzo-[1,2-b:4,5-b']difuran-2,6-dione (2), and 4-tert-butyl-2-(dicyano-methylene)-5-[4-(diethylamino)-benzylidene]-Δ(3)-thiazoline (3) as solvatochromic probes were coadsorbed onto zinc oxide to measure various effects of surface polarity. The experimental findings showed that the adsorption mechanism of PVFA and PVFA-co-PVAm strongly depends on the degree of hydrolysis of PVFA and pH values and also on the kind of metal or metal oxide surfaces that were employed as adsorbents. The adsorption mechanism of PVFA/PVFA-co-PVAm onto zinc oxide and iron oxide surfaces is mainly affected by electrostatic interactions. Particularly in the region of pH 5, the adsorption of PVFA/PVFA-co-PVAm onto zinc and iron metal particles is additionally influenced by redox processes, dissolution, and complexation reactions. © 2011 American Chemical Society

Persulfate activation by iron oxide-immobilized MnO2 composite: identification of iron oxide and the optimum pH for degradations.

Science.gov (United States)

Jo, Young-Hoon; Do, Si-Hyun; Kong, Sung-Ho

2014-01-01

Iron oxide-immobilized manganese oxide (MnO2) composite was prepared and the reactivity of persulfate (PS) with the composite as activator was investigated for degradation of carbon tetrachloride and benzene at various pH levels. Brunauer-Emmett-Teller (BET) surface area of the composite was similar to that of pure MnO2 while the pore volume and diameter of composite was larger than those of MnO2. Scanning electron microscopy couples with energy dispersive spectroscopy (SEM-EDS) showed that Fe and Mn were detected on the surface of the composite, and X-ray diffraction (XRD) analysis indicated the possibilities of the existence of various iron oxides on the composite surface. Furthermore, the analyses of X-ray photoelectron (XPS) spectra revealed that the oxidation state of iron was identified as 1.74. In PS/composite system, the same pH for the highest degradation rates of both carbon tetrachloride and benzene were observed and the value of pH was 9. Scavenger test was suggested that both oxidants (i.e. hydroxyl radical, sulfate radical) and reductant (i.e. superoxide anion) were effectively produced when PS was activated with the iron-immobilized MnO2. Copyright © 2013 Elsevier Ltd. All rights reserved.

Ultrasonic-assisted synthesis and magnetic studies of iron oxide/MCM-41 nanocomposite

International Nuclear Information System (INIS)

Ursachi, Irina; Vasile, Aurelia; Ianculescu, Adelina; Vasile, Eugeniu; Stancu, Alexandru

2011-01-01

Highlights: → A quick and facile route for the synthesis of iron oxide/MCM-41 nanocomposite. → Magnetic nanoparticles were stabilized inside the pores of mesoporous silica MCM-41. → The pore size of MCM-41 dictates the properties of iron oxide nanoparticles. → The procedure provides a narrow size distribution of magnetic nanoparticles. - Abstract: Iron oxide nanoparticles were stabilized within the pores of mesoporous silica MCM-41 amino-functionalized by a sonochemical method. Formation of iron oxide nanoparticles inside the mesoporous channels of amino-functionalized MCM-41 was realized by wet impregnation using iron nitrate, followed by calcinations at 550 deg. C in air. The effect of functionalization level on structural and magnetic properties of obtained nanocomposites was studied. The resulting materials were characterized by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy and selected area electron diffraction (HRTEM and SAED), vibrating sample and superconducting quantum interface magnetometers (VSM and SQUID) and nitrogen adsorption-desorption isotherms measurements. The HRTEM images reveal that the most of the iron oxide nanoparticles were dispersed inside the mesopores of silica matrix and the pore diameter of the amino-functionalized MCM-41 matrix dictates the particle size of iron oxide nanoparticles. The obtained material possesses mesoporous structure and interesting magnetic properties. Saturation magnetization value of magnetic iron oxide nanopatricles stabilized in MCM-41 amino-functionalized by in situ sonochemical synthesis was 1.84 emu g -1 . An important finding is that obtained magnetic nanocomposite materials exhibit enhanced magnetic properties than those of iron oxide/MCM-41 nanocomposite obtained by conventional method. The described method is providing a rather short preparation time and a narrow size distribution of iron oxide nanoparticles.

Recovery of gold and uranium from calcines

Energy Technology Data Exchange (ETDEWEB)

Livesey-Goldblatt, E.

1981-10-06

The invention concerns the recovery of non-ferrous metals, such as gold, uranium or the like from iron oxide containing calcines which have the non-ferrous metal present in solid solution and/or encapsulated within the iron oxide. The calcine is reacted, while stirring vigorously, with sulphuric acid or another strong inorganic acid to cause the iron to form the ferric salt. The material obtained is mixed with water and the liquid and solid phases are separated from each other. The non-ferrous metal is then obtained from at least one of these phases by leaching, or the like.

Iron oxides, divalent cations, silica, and the early earth phosphorus crisis

DEFF Research Database (Denmark)

Jones, C.; Nomosatryo, S.; Crowe, S.A.

2015-01-01

As a nutrient required for growth, phosphorus regulates the activity of life in the oceans. Iron oxides sorb phosphorus from seawater, and through the Archean and early Proterozoic Eons, massive quantities of iron oxides precipitated from the oceans, producing a record of seawater chemistry...... that is preserved as banded iron formations (BIFs) today. Here we show that Ca2+, Mg2+, and silica in seawater control phosphorus sorption onto iron oxides, influencing the record of seawater phosphorus preserved in BIFs. Using a model for seawater cation chemistry through time, combined with the phosphorus...... waters shifted from phosphorus to iron limiting....

Dissolution of oxide films on iron in aqueous solutions containing complexing anions

International Nuclear Information System (INIS)

Shoesmith, D.W.; Lee, W.; Owen, D.G.

1981-01-01

The dissolution, in oxalic acid and oxalic acid plus ethylenediaminetetraacetate, of magnetite films grown at high temperature on iron has been studied under varying conditions of pH and temperature. For oxalate concentrations greater than about 2 x 10 -3 mol dm -3 , magnetite dissolves by direct chemical dissolution. The mechanism appears to involve adsorption of oxalate ions at ferric ion sites in the oxide lattice, followed by proton attack and desorption of cationic species. Once metal dissolution starts, β-ferrous oxalate dihydrate is precipitated on the electrode, leading to erratic fluctuations in the electrode potential and eventually to inhibition of metal dissolution. For oxalate concentrations -3 mol dm -3 , the predominant dissolution mechanism appears to involve reduction by the metal. Also, once solution penetration to the underlying metal has occurred, and the electrode has returned to the active state, autoreductive dissolution appears to predominate even at higher oxalate concentrations. This change in mechanism from predominantly chemical dissolution to predominantly autoreductive dissolution may be due, at least in part, to the desorption of oxalate ions at the more negative potentials achieved in the active state. (author)

Long-term intake of iron fortified wholemeal rye bread appears to benefit iron status of young women

DEFF Research Database (Denmark)

Hansen, Max; Nielsen, Sussi Bæch; Thomsen, A.D.

2005-01-01

The efficacy of intake of iron fortified, wholemeal rye bread on iron status of young women with low iron stores was evaluated in a 5 month single-blind intervention study. Two parallel groups of women (20-38 y) were given 144 g of rye bread/d either fortified with 6 mg iron as ferrous fumarate/100...... stores of young women with poor iron status which were otherwise reduced by intake of the unfortified control bread....

Synthesis of iron oxide nanoparticles via sonochemical method and their characterization

Institute of Scientific and Technical Information of China (English)

Amir Hassanjani-Roshan; Mohammad Reza Vaezi; Ali Shokuhfar; Zohreh Rajabali

2011-01-01

Preparation of iron oxide (α-Fe2O3) nanoparticles was carried out via a sonochemical process. The process parameters such as temperature,sonication time and power of ultrasonication play important roles in the size and morphology of the final products. The iron oxide nanoparticles were characterized by transmission electron microscopy,X-ray powder diffraction,and thermogravimetric and differential thermal analyses. From transmission electron microscopy observations,the size of the iron oxide nanoparticles is estimated to be significantly smaller than 19 nm. X-ray diffraction data of the powder after annealing provide direct evidence that the iron oxide was formed during the sonochemical process.

Synthesis of iron oxide nanoparticles of narrow size distribution on ...

Indian Academy of Sciences (India)

WINTEC

Abstract. We report here the preparation of nanoparticles of iron oxide in the presence of polysaccharide templates. ... using different chemical methods viz. sonochemical, sol- .... 3.2 Characterization of iron oxide prepared by template assisted ...

Hydrogen production by ethanol partial oxidation over nano-iron oxide catalysts produced by chemical vapour synthesis

Energy Technology Data Exchange (ETDEWEB)

Ahmed, Wael Ahmed Abou Taleb Sayed

2011-01-13

This work presents the experimental results of the synthesis of unsupported and supported SiC iron oxide nanoparticles and their catalytic activity towards ethanol partial oxidation. For comparison, further unsupported iron oxide phases were investigated towards the ethanol partial oxidation. These {gamma}-Fe{sub 2}O{sub 3} and {alpha}/{gamma}-Fe{sub 2}O{sub 3} phase catalysts were prepared by the CVS method using Fe(CO){sub 5} as precursor, supplied by another author. The {alpha}-Fe{sub 2}O{sub 3} and SiC nanoparticles were prepared by the CVS method using a home made hot wall reactor technique at atmospheric pressure. Ferrocene and tetramethylsilane were used as precursor for the production process. Process parameters of precursor evaporation temperature, precursor concentration, gas mixture velocity and gas mixture dilution were investigated and optimised to produce particle sizes in a range of 10 nm. For Fe{sub 2}O{sub 3}/SiC catalyst series production, a new hot wall reactor setup was used. The particles were produced by simultaneous thermal decomposition of ferrocene and tetramethylsilane in one reactor from both sides. The production parameters of inlet tube distance inside the reactor, precursor evaporation temperature and carrier gas flow were investigated to produce a series of samples with different iron oxide content. The prepared catalysts composition, physical and chemical properties were characterized by XRD, EDX, SEM, BET surface area, FTIR, XPS and dynamic light scattering (DLS) techniques. The catalytic activity for the ethanol gas-phase oxidation was investigated in a temperature range from 260 C to 290 C. The product distributions obtained over all catalysts were analysed with mass spectrometry analysis tool. The activity of bulk Fe{sub 2}O{sub 3} and SiC nanoparticles was compared with prepared nano-iron oxide phase catalysts. The reaction parameters, such as reaction temperature and O{sub 2}/ethanol ratio were investigated. The catalysts

Sorption of trace amounts of gallium (III) on iron (III) oxide

International Nuclear Information System (INIS)

Music, S.; Gessner, M.; Wolf, R.H.H.

1979-01-01

The sorption of trace amounts of gallium(III) on iron(III) oxide has been studied as a function of pH. Optimum conditions have been found for the preconcentration of traces of gallium(III) by iron(III) oxide. The influence of surface active substances and of complexing agents on the sorption of trace amounts of gallium(III) on iron(III) oxide has been also studied. (orig.) [de

Sorption of trace amounts of gallium (III) on iron (III) oxide

Energy Technology Data Exchange (ETDEWEB)

Music, S; Gessner, M; Wolf, R H.H. [Institut Rudjer Boskovic, Zagreb (Yugoslavia)

1979-01-01

The sorption of trace amounts of gallium(III) on iron(III) oxide has been studied as a function of pH. Optimum conditions have been found for the preconcentration of traces of gallium(III) by iron(III) oxide. The influence of surface active substances and of complexing agents on the sorption of trace amounts of gallium(III) on iron(III) oxide has been also studied.

Magnetic iron oxide for contrast-enhanced MR imaging

International Nuclear Information System (INIS)

Fahlvik, A.K.

1991-05-01

The main objective of this experimental work has been to study the biological fate and the contrast enhancing potential of a model preparation of magnetic iron oxide (MSM) after intravenous injection to rodents. This was achieved by: Studying in vitro contrast efficacy of various magnetic iron oxide preparations by relaxation analysis. Studying in vivo contrast efficacy of MSM by relaxation analysis and NMR imaging. Studying the biodistribution and bioelimination of MSM in independent experiments using relaxation analysis, radioactivity studies and histological techniques. Studying interactions of MSM with target cells and target organelles using ex vivo techniques. Based on the presented experimental study, the MSM model preparation of magnetic iron oxide seems to fulfill basic requirements of NMR contrast agents: efficient proton relaxation, specific in vivo distribution, and biological tolerance. 177 refs., 5 figs., 2 tabs

Reactivity of Uranium and Ferrous Iron with Natural Iron Oxyhydroxides.

Science.gov (United States)

Stewart, Brandy D; Cismasu, A Cristina; Williams, Kenneth H; Peyton, Brent M; Nico, Peter S

2015-09-01

Determining key reaction pathways involving uranium and iron oxyhydroxides under oxic and anoxic conditions is essential for understanding uranium mobility as well as other iron oxyhydroxide mediated processes, particularly near redox boundaries where redox conditions change rapidly in time and space. Here we examine the reactivity of a ferrihydrite-rich sediment from a surface seep adjacent to a redox boundary at the Rifle, Colorado field site. Iron(II)-sediment incubation experiments indicate that the natural ferrihydrite fraction of the sediment is not susceptible to reductive transformation under conditions that trigger significant mineralogical transformations of synthetic ferrihydrite. No measurable Fe(II)-promoted transformation was observed when the Rifle sediment was exposed to 30 mM Fe(II) for up to 2 weeks. Incubation of the Rifle sediment with 3 mM Fe(II) and 0.2 mM U(VI) for 15 days shows no measurable incorporation of U(VI) into the mineral structure or reduction of U(VI) to U(IV). Results indicate a significantly decreased reactivity of naturally occurring Fe oxyhydroxides as compared to synthetic minerals, likely due to the association of impurities (e.g., Si, organic matter), with implications for the mobility and bioavailability of uranium and other associated species in field environments.

Study of iron valence state and position in sub-site by Moessbauer spectroscopy

International Nuclear Information System (INIS)

Uhm, Young Rang; Lim, Jae Cheong; KIm, Chul Sung; Son, Kwang Jae

2014-01-01

The magnetic ordering temperature and the magnitude of the magnetic fields at the iron sites of YIG can be influenced by substituting, either partially or totally, the Fe 3+ ions at the octahedral and/or the tetrahedral sites with magnetic or diamagnetic ions, and/or by substitution the Y 3+ ions at the dodecahedral sites with magnetic rare earth ions. It has been known for some time that Moessbauer spectroscopy is a powerful method by which iron-containing garnets can be studied. We report here on the synthesis of the compounds with garnet-related structures of composition Y 3 Fe 4.5 Cr 0.5 O 12 and its examination by 57 Fe Moessbauer spectroscopy. The chromium in compounds of the Y 3 Fe 4.5 Cr 0.5 O 12 is distributed at an octahedral site. The Moessbauer spectra can be analyzed using 3 or 4 sets of six Lorentzians with increasing amount of Cr 3+ compounds in this system. It results from the distribution ( 4 C n ) of Fe 3+ and Cr 3+ at an octahedral site. A comparative study of ferrous tablets of Dynabi was carried out using Moessbauer spectroscopy. The obtained results revealed the presence of ferrous (Fe 2+ ) gluconate and ferrous fumarate in a sample. This observation is important to better control the iron state in such medicaments because their pharmaceutical effect in the body is related to the form and valence of iron. The Cr-containing yttrium iron garnet (YIG), and the exchange interactions and site distributions were studied using 57 Fe Moessbauer spectroscopy. The obtained results revealed the presence of ferrous (Fe 2+ ) gluconate and ferrous fumarate in the sample. This observation is important better control the iron state in such medicaments because their pharmaceutical effect in the body is related to the form and valence of iron

Thermomagnetic identification of manganese and iron minerals present in soils and industrial dusts

Science.gov (United States)

Wawer, Małgorzata; Rachwał, Marzena; Jabłońska, Mariola; Krzykawski, Tomasz; Magiera, Tadeusz

2017-04-01

Many industries (e.g. metallurgy, power, cement, and coking plants) constitute a sources of industrial dusts containing technogenic magnetic particles (TMP). TMP are mostly iron oxides with ferrimagnetic or antiferromagnetic properties, therefore their presence in dusts, soils and sediments can be easily detected by magnetic susceptibility measurements. TMP, thanks their specific mineral and magnetic properties, and well developed specific surface area, are characterized by a chemical affinity for some elements like heavy metals. The main objective of this study was identification of manganese and iron (hydro)oxides occurring in industrial dusts and soils being under their deposition for long time period. In principle, Mn and Fe (hydro)oxides present in these samples originate from high-temperature technological processes. Soils samples (collected from different soil horizons) taken from surroundings of power station, iron/steel and non-ferrous plants as well as metallurgical dusts and fly ashes from power stations were subjected to investigation. During the studies temperature dependent magnetic susceptibility measurements and X-ray powder diffraction analyses were applied. Thermomagnetic analyses (K-T) revealed differences between samples from particular industries, however an inflexion at 450-500°C of all curves was observed indicating a probable occurrence of maghemite- or titanomagnetite-like phases. The curves of TMP emitted by power plants have inflection at 580 °C indicating that magnetite was the main magnetic phase. In case of TMP originated from non-ferrous metal smelting additional curve deflection at 130 and 210 °C occurred relating to intermediate titanomagnetite or iron sulfides. X-ray diffraction proved the occurrence of magnetite and maghemite in almost all samples, especially connected with power industry and iron/steel metallurgy. Mineral analysis revealed that kind of industrial process influenced on the dominating mineral forms found in

Synthesis and Evaluation of Nanostructured Gold-Iron Oxide Catalysts for the Oxidative Dehydrogenation of Cyclohexane

Science.gov (United States)

Wu, Peng

Shape-controlled iron oxide and gold-iron oxide catalysts with a cubic inverse spinel structure were studied in this thesis for the oxidative dehydrogenation of cyclohexane. The structure of iron oxide and gold-iron oxide catalysts has no major impact on their oxidative dehydrogenation activity. However, the product selectivity is influenced. Both cyclohexene and benzene are formed on bare iron oxide nanoshapes, while benzene is the only dehydrogenation product in the presence of gold. The selectivity of benzene over CO2 depends strongly on the stability of the iron oxide support and the gold-support interaction. The highest benzene yield has been observed on gold-iron oxide octahedra. {111}-bound nanooctahedra are highly stable in reaction conditions at 300 °C, while {100}-bound nanocubes start to sinter above 250 °C. The highest benzene yield has been observed on gold-iron oxide nanooctahedra, which are likely to have gold atoms, and few-atom gold clusters strongly-bound on their surface. Cationic gold appears to be the active site for benzene formation. An all-organic method to prepare Au-FeOx nano-catalysts is needed due to the inconvenience of the half-organic, half-inorganic synthesis process discussed above. Several methods from the literature to prepare gold-iron oxide nanocomposites completely in organic solvents were reviewed and followed. FeOx Au synthesis procedures in literatures are initially designed for a Au content of over 70%. This approach was tried here to prepare composites with a much lower Au content (2-5 atom. %). Heat treatment is required to bond Au and FeOx NPs in the organic-phase syntheses. Au-FeOx-4 was obtained as a selective catalyst for the ODH of cyclohexane. A Audelta+ peak is observed in the UV-Vis spectrum of sample Au-FeOx-4. This different Au delta+ form may be cationic Au nano-clusters interacting with the FeOx support. It has been demonstrated that cationic gold is responsible for dehydrogenation behavior. Furthermore, the

Microanalysis of iron oxidation state in iron oxides using X Ray Absorption Near Edge Structure (XANES)

Science.gov (United States)

Sutton, S. R.; Delaney, J.; Bajt, S.; Rivers, M. L.; Smith, J. V.

1993-01-01

An exploratory application of x ray absorption near edge structure (XANES) analysis using the synchrotron x ray microprobe was undertaken to obtain Fe XANES spectra on individual sub-millimeter grains in conventional polished sections. The experiments concentrated on determinations of Fe valence in a suite of iron oxide minerals for which independent estimates of the iron speciation could be made by electron microprobe analysis and x ray diffraction.

Hybrid dextran-iron oxide thin films deposited by laser techniques for biomedical applications

International Nuclear Information System (INIS)

Predoi, D.; Ciobanu, C.S.; Radu, M.; Costache, M.; Dinischiotu, A.; Popescu, C.; Axente, E.; Mihailescu, I.N.; Gyorgy, E.

2012-01-01

Iron oxide nanoparticles were prepared by chemical co-precipitation method. The nanoparticles were mixed with dextran in distilled water. The obtained solutions were frozen in liquid nitrogen and used as targets during matrix assisted pulsed laser evaporation for the growth of hybrid, iron oxide nanoparticles-dextran thin films. Fourier Transform Infrared Spectroscopy and X-ray diffraction investigations revealed that the obtained films preserve the structure and composition of the initial, non-irradiated iron oxide-dextran composite material. The biocompatibility of the iron oxide-dextran thin films was demonstrated by 3-(4.5 dimethylthiazol-2yl)-2.5-diphenyltetrazolium bromide-based colorimetric assay, using human liver hepatocellular carcinoma cells. - Highlights: ► Hybrid, dextran-iron oxide nanoparticles and thin films. ► Laser immobilization. ► Biocompatibility of dextran-iron oxide nanoparticles.

Thermochemically active iron titanium oxide materials

Energy Technology Data Exchange (ETDEWEB)

Coker, Eric Nicholas; Miller, James E.

2018-01-16

A thermal oxidation-reduction cycle is disclosed that uses iron titanium oxide as the reactive material. The cycle may be used for the thermal splitting of water and/or carbon dioxide to form hydrogen and/or carbon monoxide. The formed compounds may be used as syngas precursors to form fuels.

Sulfur Cycling in an Iron Oxide-Dominated, Dynamic Marine Depositional System: The Argentine Continental Margin

Directory of Open Access Journals (Sweden)

Natascha Riedinger

2017-05-01

Full Text Available The interplay between sediment deposition patterns, organic matter type and the quantity and quality of reactive mineral phases determines the accumulation, speciation, and isotope composition of pore water and solid phase sulfur constituents in marine sediments. Here, we present the sulfur geochemistry of siliciclastic sediments from two sites along the Argentine continental slope—a system characterized by dynamic deposition and reworking, which result in non-steady state conditions. The two investigated sites have different depositional histories but have in common that reactive iron phases are abundant and that organic matter is refractory—conditions that result in low organoclastic sulfate reduction rates (SRR. Deposition of reworked, isotopically light pyrite and sulfurized organic matter appear to be important contributors to the sulfur inventory, with only minor addition of pyrite from organoclastic sulfate reduction above the sulfate-methane transition (SMT. Pore-water sulfide is limited to a narrow zone at the SMT. The core of that zone is dominated by pyrite accumulation. Iron monosulfide and elemental sulfur accumulate above and below this zone. Iron monosulfide precipitation is driven by the reaction of low amounts of hydrogen sulfide with ferrous iron and is in competition with the oxidation of sulfide by iron (oxyhydroxides to form elemental sulfur. The intervals marked by precipitation of intermediate sulfur phases at the margin of the zone with free sulfide are bordered by two distinct peaks in total organic sulfur (TOS. Organic matter sulfurization appears to precede pyrite formation in the iron-dominated margins of the sulfide zone, potentially linked to the presence of polysulfides formed by reaction between dissolved sulfide and elemental sulfur. Thus, SMTs can be hotspots for organic matter sulfurization in sulfide-limited, reactive iron-rich marine sedimentary systems. Furthermore, existence of elemental sulfur and iron

Solid-state Water-mediated Transport Reduction of Nanostructured Iron Oxides

International Nuclear Information System (INIS)

Smirnov, Vladimir M.; Povarov, Vladimir G.; Voronkov, Gennadii P.; Semenov, Valentin G.; Murin, Igor' V.; Gittsovich, Viktor N.; Sinel'nikov, Boris M.

2001-01-01

The Fe 2+ /Fe 3+ ratio in two-dimensional iron oxide nanosructures (nanolayers with a thickness of 0.3-1.5 nm on silica surface) may be precisely controlled using the transport reduction (TR) technique. The species ≡-O-Fe(OH) 2 and (≡Si-O-) 2 -FeOH forming the surface monolayer are not reduced at 400-600 deg. C because of their covalent bonding to the silica surface, as demonstrated by Moessbauer spectroscopy. Iron oxide microparticles (microstructures) obtained by the impregnation technique, being chemically unbound to silica, are subjected to reduction at T ≥ 500 deg. C with formation of metallic iron in the form of α-Fe. Transport reduction of supported nanostructures (consisting of 1 or 4 monolayers) at T ≥ 600 deg. C produces bulk iron(II) silicate and metallic iron phases. The structural-chemical transformations occurring in transport reduction of supported iron oxide nanolayers are proved to be governed by specific phase processes in the nanostructures themselves

Performance of the electrical generator cell by the ferrous alloys of printed circuit board scrap and Iron Metal 1020

Science.gov (United States)

Sahan, Y.; Sudarsono, S.; Silviana, E.; Chairul; Wisrayetti

2018-04-01

Galvani cell is one of thealternative energy. This cell can be used as an electric resources. In this research, the generator cell was designed and builds to generate the electric. The generator cell consisted of the iron metal 1020 were used as anode, the ferrous alloys of printed circuit board scrapwas then used as chatode, and NaCl solution as an electrolyte. The aim of this research is to estimate the performance of this generator cell by using variation of NaCl concentration (i.e. 1%, 3%, 5%, 7%, and 9%) with the electrodes pair ( 1 and 8 pairs). The performance of the cell was measured with a multi tester equipment and a LED bulb (5-watt 3Volt). The Results shown that the generator cell can produce the electric power of 3.679 Volt maximally by using NaCl 9% and 8 electrode pairs applied for this condition.

Molecular and parametric imaging with iron oxides

International Nuclear Information System (INIS)

Matuszewski, L.; Bremer, C.; Tombach, B.; Heindel, W.

2007-01-01

Superparamagnetic iron oxide (SPIO) contrast agents, clinically established for high resolution magnetic resonance imaging of reticuloendothelial system containing anatomical structures, can additionally be exploited for the non-invasive characterization and quantification of pathology down to the molecular level. In this context, SPIOs can be applied for non-invasive cell tracking, quantification of tissue perfusion and target specific imaging, as well as for the detection of gene expression. This article provides an overview of new applications for clinically approved iron oxides as well of new, modified SPIO contrast agents for parametric and molecular imaging. (orig.) [de

Iron and manganese oxides modified maize straw to remove tylosin from aqueous solutions.

Science.gov (United States)

Yin, Yongyuan; Guo, Xuetao; Peng, Dan

2018-08-01

Maize straw modified by iron and manganese oxides was synthesized via a simple and environmentally friendly method. Three maize straw materials, the original maize straw, maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides, were detected by SEM, BET, XPS, XRD and FTIR. The results showed that maize straw was successfully modified and maize straw modified by iron and manganese oxides has a larger surface area than MS. According to the experimental data, the sorption trend could conform to the pseudo-second-order kinetic model well, and the sorption ability of tylosin on sorbents followed the order of original maize straw oxides iron and manganese oxides. The study indicated that manganese oxides and iron-manganese oxides could significantly enhance the sorption capacity of original maize straw. The sorption isotherm data of tylosin on original maize straw fit a linear model well, while Freundlich models were more suitable for maize straw modified by manganese oxides and maize straw modified by iron and manganese oxides. The pH, ionic strength and temperature can affect the sorption process. The sorption mechanisms of tylosin on iron and manganese oxides modified maize straw were attribute to the surface complexes, electrostatic interactions, H bonding and hydrophobic interactions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Rapid quantification of iron content in fish sauce and soy sauce: a promising tool for monitoring fortification programs.

Science.gov (United States)

Laillou, Arnaud; Icard-Vernière, Christèle; Rochette, Isabelle; Picq, Christian; Berger, Jacques; Sambath, Pol; Mouquet-Rivier, Claire

2013-06-01

In a number of Southeast Asian countries and China, fish sauce and soy sauce produced at the industrial level are fortified with iron. Unfortunately, the food producers and regulatory agencies implementing fortification programs do not always have the capacity to monitor the programs on an ongoing basis. To assess a new portable device for the quantitative measurement of iron content of fortified sauces that could be used to control fortification levels. The linearity, detection limits, and inter- and intraassay variability of this device were assessed on fish sauce and soy sauce fortified with ferrous sulfate, ferrous fumarate, and sodium iron ethylenediaminetetraacetate (NaFeEDTA); the accuracy of the results was determined by comparing them with the results obtained by atomic absorption spectrophotometry. Measurements required a minimum incubation time of 1 hour for iron sulfate or iron fumarate and 24 hours for NaFeEDTA. Linearity of the results ranged from 2 to 10 mg iron/L for ferrous sulfate or ferrous fumarate and from 1 to 10 mg iron/L for NaFeEDTA, implying the need for proper dilution, as the iron contents of fortified sauce are usually in the range of 150 to 1,000 mg/L. Depending on incubation time, iron compounds, and sauces, the coefficient of variation (CV) of intraassay precision was between 1.5% and 7.6% and the CV of interassay precision was between 2.9% and 7.4%. Comparison with results from atomic absorption spectrophotometry showed high agreement between both methods, with R = 0.926 and R = 0.935 for incubation times of 1 hour and 24 hours, respectively. The Bland-Altman plots showed limits of agreement between the two methods of +/- 70 mg/L in the range of fortification levels tested (100 to 500 mg/L). CONCLUSIONS; This device offers a viable method for field monitoring of iron fortification of soy and fish sauces after incubation times of 1 hour for ferrous sulfate or ferrous fumarate and 24 hours for NaFeEDTA.

Iron plaque decreases cadmium accumulation in Oryza sativa L. and serves as a source of iron.

Science.gov (United States)

Sebastian, A; Prasad, M N V

2016-11-01

Cadmium (Cd) contamination occurs in paddy soils; hence it is necessary to reduce Cd content of rice. Application and mode of action of ferrous sulphate in minimizing Cd in rice was monitored in the present study. Pot culture with Indian rice variety Swarna (MTU 7029) was maintained in Cd-spiked soil containing ferrous sulphates, which is expected to reduce Cd accumulation in rice. Responses in rhizosphere pH, root surface, metal accumulation in plant and molecular physiological processes were monitored. Iron plaque was induced on root surfaces after FeSO4 application and the amount of Fe in plaque reduced with increases in Cd in the soil. Rhizosphere pH decreased during plaque formation and became more acidic due to secretion of organic acids from the roots under Cd treatment. Moreover, iron chelate reductase activity increased with Cd treatment, but in the absence of Cd, activity of this enzyme increased in plaque-induced plants. Cd treatment caused expression of OsYSL18, whereas OsYSL15 was expressed only in roots without iron plaque. Fe content of plants increased during plaque formation, which protected plants from Cd-induced Fe deficiency and metal toxicity. This was corroborated with increased biomass, chlorophyll content and quantum efficiency of photo-synthesis among plaque-induced plants. We conclude that ferrous sulphate-induced iron plaque prevents Cd accumulation and Fe deficiency in rice. Iron released from plaque via organic acid mediated dissolution during Cd stress. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

Antioxidant mechanism of milk mineral-high-affinity iron binding.

Science.gov (United States)

Allen, K; Cornforth, D

2007-01-01

Milk mineral (MM), a by-product of whey processing, is an effective antioxidant in meat systems, but the antioxidant mechanism has not been established. MM has been postulated to chelate iron and prevent iron-catalysis of lipid oxidation. The objective of this research was to examine this putative mechanism. MM was compared to sodium tripolyphosphate (STPP), calcium phosphate monobasic (CPM), and calcium pyrophosphate (CPP) to determine iron-binding capacity, sample solubility, and eluate soluble phosphorus after treating samples with a ferrous chloride standard. Scanning electron microscopy with energy-dispersive X-ray analysis was used to localize minerals on iron-treated MM particle surfaces. Histochemical staining for calcium was performed on raw and cooked ground beef samples with added MM. MM bound more iron per gram (P compounds, and was much less soluble (P iron across the MM particle surface, directly demonstrating iron binding to MM particles. Unlike other common chelating agents, such as STPP and citrate, histochemical staining demonstrated that MM remained insoluble in ground beef, even after cooking. The ability of MM to bind iron and remain insoluble may enhance its antioxidant effect by removing iron ions from solution. However, MM particles must be small and well distributed in order to adequately bind iron throughout the food system.

Iron absorption after antrectomy with gastroduodenostomy

International Nuclear Information System (INIS)

Magnusson, B.E.O.

1976-01-01

Haematological values were studied in 177 unselected patients 3-6 years after antrectomy with gastroduodenostomy. The majority (76%) had been operated upon for duodenal ulcer, 20% for gastric ulcer and the remaining patients had had both a duodenal and a gastric ulcer before the operation. In 65 patients a vagotomy had been added to the resection. 10% of the males and 15% of the females had a haemoglobin concentration below 13.0 or 12.0 g/100 ml, respectively. The corresponding frequencies for iron defifiency, defined as absence or only traces of haemosiderin in bone marrow smears, were 7% and 15%. The absorption of a small test dose of inorganic iron (0.56 mg Fe ++ as ferrous ascorbate) was studied in all the antrectomized patients. The absorption was also investigated in normal men and in patients who had had a Billroth II partial gastrectomy. No malabsorption of inorganic iron could be found in any of the groups. An inverse relationship between iron absorption and the grading of haemosiderin in bone marrow smears was found in normal subjects as well as in operated patients. Thus, an adequate increase of the absorption of ferrous iron was found even in operated patients with iron deficiency. Gastric acid secretion, measured as the peak acid output (PAO) after stimulation, was determined in all antrectomized patients. In patients having the same grading of haemosiderin (grade II) a slight but significant positive correlation was found between PAO and the absorption from the test dose (Fe ++ ). The absorption of food iron from a composite meal and the absorption from an iron salt (3.0 mg Fe ++ as ferrous ascorbate) was studied in 4 different groups: 1) normal males, 2) non-operated patients with peptic ulcer, 3) antrectomized patients with gastroduodenostomy and 4) patients operated upon with Billroth II partial gastrectomy. The range and mean absorption values from the test dose of inorganic iron were about the same in all groups. The absorption of food iron

Hybrid dextran-iron oxide thin films deposited by laser techniques for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Predoi, D.; Ciobanu, C.S. [National Institute for Physics of Materials, P.O. Box MG 07, Bucharest, Magurele (Romania); Radu, M.; Costache, M.; Dinischiotu, A. [Molecular Biology Center, University of Bucharest, 91-95 Splaiul Independentei, 76201, Bucharest 5 (Romania); Popescu, C.; Axente, E.; Mihailescu, I.N. [National Institute for Lasers, Plasma and Radiations Physics, P. O. Box MG 36, 77125 Bucharest (Romania); Gyorgy, E., E-mail: egyorgy@cin2.es [National Institute for Lasers, Plasma and Radiations Physics, P. O. Box MG 36, 77125 Bucharest (Romania); Consejo Superior de Investigaciones Cientificas, Centre d' Investigacions en Nanociencia i Nanotecnologia (CSIC-CIN2), Campus UAB, 08193 Bellaterra (Spain)

2012-02-01

Iron oxide nanoparticles were prepared by chemical co-precipitation method. The nanoparticles were mixed with dextran in distilled water. The obtained solutions were frozen in liquid nitrogen and used as targets during matrix assisted pulsed laser evaporation for the growth of hybrid, iron oxide nanoparticles-dextran thin films. Fourier Transform Infrared Spectroscopy and X-ray diffraction investigations revealed that the obtained films preserve the structure and composition of the initial, non-irradiated iron oxide-dextran composite material. The biocompatibility of the iron oxide-dextran thin films was demonstrated by 3-(4.5 dimethylthiazol-2yl)-2.5-diphenyltetrazolium bromide-based colorimetric assay, using human liver hepatocellular carcinoma cells. - Highlights: Black-Right-Pointing-Pointer Hybrid, dextran-iron oxide nanoparticles and thin films. Black-Right-Pointing-Pointer Laser immobilization. Black-Right-Pointing-Pointer Biocompatibility of dextran-iron oxide nanoparticles.

Regeneration of iron oxide containing pellets used for hot gas clean up

Energy Technology Data Exchange (ETDEWEB)

Palmer, A.; Heeney, P.; Furimsky, E. (CANMET, Ottawa, Ontario (Canada). Energy Research Laboratories)

1989-09-01

Four iron-containing pelletized solids used for H{sub 2}S removal from hot gas were oxidized in a Cahn electrobalance and in a fixed bed reactor. The main reactions included the sequence in which FeS was oxidized to iron sulphate which then decomposed rapidly yielding SO{sub 2} and iron oxides. The oxidation occurred predominantly on the outer surface of the pellets. 12 refs., 5 figs., 5 tabs.

Iron oxides photochemical dissolution

International Nuclear Information System (INIS)

Blesa, M.A.; Litter, M.I.

1987-01-01

This work was intended to study the light irradiation influence of diverse wave-lengths on iron oxides dissolution in aqueous solutions. The objectives of this work were: the exploration of photochemical processes with the aim of its eventual application in: a) decontamination and chemical cleaning under special conditions; b) materials for solar energy conversion. (Author)

Magnetic and Mössbauer spectroscopy studies of nanocrystalline iron oxide aerogels

DEFF Research Database (Denmark)

Carpenter, E.E.; Long, J.W.; Rolison, D.R.

2006-01-01

A sol-gel synthesis was used to produce iron oxide aerogels. These nanocrystalline aerogels have a pore-solid structure similar to silica aerogels but are composed entirely of iron oxides. Mössbauer experiments and x-ray diffraction showed that the as-prepared aerogel is an amorphous or poorly...... crystalline iron oxide, which crystallized as a partially oxidized magnetite during heating in argon. After further heat treatment in air, the nanocrystallites are fully converted to maghemite. The particles are superparamagnetic at high temperatures, but the magnetic properties are strongly influenced...

Aqueous dispersion of monodisperse magnetic iron oxide nanocrystals through phase transfer

International Nuclear Information System (INIS)

Yu, William W; Chang, Emmanuel; Sayes, Christie M; Drezek, Rebekah; Colvin, Vicki L

2006-01-01

A facile method was developed for completely transferring high quality monodisperse iron oxide nanocrystals from organic solvents to water. The as-prepared aqueous dispersions of iron oxide nanocrystals were extremely stable and could be functionalized for bioconjugation with biomolecules. These iron oxide nanocrystals showed negligible cytotoxicity to human breast cancer cells (SK-BR-3) and human dermal fibroblast cells. This method is general and versatile for many organic solvent-synthesized nanoparticles, including fluorescent semiconductor nanocrystals

Identification and Analysis of a Novel Gene Cluster Involves in Fe2+ Oxidation in Acidithiobacillus ferrooxidans ATCC 23270, a Typical Biomining Acidophile.

Science.gov (United States)

Ai, Chenbing; Liang, Yuting; Miao, Bo; Chen, Miao; Zeng, Weimin; Qiu, Guanzhou

2018-07-01

Iron-oxidizing Acidithiobacillus spp. are applied worldwide in biomining industry to extract metals from sulfide minerals. They derive energy for survival through Fe 2+ oxidation and generate Fe 3+ for the dissolution of sulfide minerals. However, molecular mechanisms of their iron oxidation still remain elusive. A novel two-cytochrome-encoding gene cluster (named tce gene cluster) encoding a high-molecular-weight cytochrome c (AFE_1428) and a c 4 -type cytochrome c 552 (AFE_1429) in A. ferrooxidans ATCC 23270 was first identified in this study. Bioinformatic analysis together with transcriptional study showed that AFE_1428 and AFE_1429 were the corresponding paralog of Cyc2 (AFE_3153) and Cyc1 (AFE_3152) which were encoded by the extensively studied rus operon and had been proven involving in ferrous iron oxidation. Both AFE_1428 and AFE_1429 contained signal peptide and the classic heme-binding motif(s) as their corresponding paralog. The modeled structure of AFE_1429 showed high resemblance to Cyc1. AFE_1428 and AFE_1429 were preferentially transcribed as their corresponding paralogs in the presence of ferrous iron as sole energy source as compared with sulfur. The tce gene cluster is highly conserved in the genomes of four phylogenetic-related A. ferrooxidans strains that were originally isolated from different sites separated with huge geographical distance, which further implies the importance of this gene cluster. Collectively, AFE_1428 and AFE_1429 involve in Fe 2+ oxidation like their corresponding paralog by integrating with the metalloproteins encoded by rus operon. This study provides novel insights into the Fe 2+ oxidation mechanism in Fe 2+ -oxidizing A. ferrooxidans ssp.

Synthesis, characterization, applications, and challenges of iron oxide nanoparticles

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Ali, Attarad; Zafar, Hira; Zia, Muhammad; ul Haq, Ihsan; Phull, Abdul Rehman; Ali, Joham Sarfraz; Hussain, Altaf

2016-01-01

Recently, iron oxide nanoparticles (NPs) have attracted much consideration due to their unique properties, such as superparamagnetism, surface-to-volume ratio, greater surface area, and easy separation methodology. Various physical, chemical, and biological methods have been adopted to synthesize magnetic NPs with suitable surface chemistry. This review summarizes the methods for the preparation of iron oxide NPs, size and morphology control, and magnetic properties with recent bioengineering, commercial, and industrial applications. Iron oxides exhibit great potential in the fields of life sciences such as biomedicine, agriculture, and environment. Nontoxic conduct and biocompatible applications of magnetic NPs can be enriched further by special surface coating with organic or inorganic molecules, including surfactants, drugs, proteins, starches, enzymes, antibodies, nucleotides, nonionic detergents, and polyelectrolytes. Magnetic NPs can also be directed to an organ, tissue, or tumor using an external magnetic field for hyperthermic treatment of patients. Keeping in mind the current interest in iron NPs, this review is designed to report recent information from synthesis to characterization, and applications of iron NPs. PMID:27578966

From iron coordination compounds to metal oxide nanoparticles.

Science.gov (United States)

Iacob, Mihail; Racles, Carmen; Tugui, Codrin; Stiubianu, George; Bele, Adrian; Sacarescu, Liviu; Timpu, Daniel; Cazacu, Maria

2016-01-01

Various types, shapes and sizes of iron oxide nanoparticles were obtained depending on the nature of the precursor, preparation method and reaction conditions. The mixed valence trinuclear iron acetate, [Fe 2 III Fe II O(CH 3 COO) 6 (H 2 O) 3 ]·2H 2 O (FeAc1), μ 3 -oxo trinuclear iron(III) acetate, [Fe 3 O(CH 3 COO) 6 (H 2 O) 3 ]NO 3 ∙4H 2 O (FeAc2), iron furoate, [Fe 3 O(C 4 H 3 OCOO) 6 (CH 3 OH) 3 ]NO 3 ∙2CH 3 OH (FeF), iron chromium furoate, FeCr 2 O(C 4 H 3 OCOO) 6 (CH 3 OH) 3 ]NO 3 ∙2CH 3 OH (FeCrF), and an iron complex with an original macromolecular ligand (FePAZ) were used as precursors for the corresponding oxide nanoparticles. Five series of nanoparticle samples were prepared employing either a classical thermal pathway (i.e., thermal decomposition in solution, solvothermal method, dry thermal decomposition/calcination) or using a nonconventional energy source (i.e., microwave or ultrasonic treatment) to convert precursors into iron oxides. The resulting materials were structurally characterized by wide-angle X-ray diffraction and Fourier transform infrared, Raman, energy-dispersive X-ray, and X-ray fluorescence spectroscopies, as well as thermogravimetric analysis. The morphology was characterized by transmission electron microscopy, atomic force microscopy and dynamic light scattering. The parameters were varied within each route to fine tune the size and shape of the formed nanoparticles.

From iron coordination compounds to metal oxide nanoparticles

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Mihail Iacob

2016-12-01

Full Text Available Various types, shapes and sizes of iron oxide nanoparticles were obtained depending on the nature of the precursor, preparation method and reaction conditions. The mixed valence trinuclear iron acetate, [Fe2IIIFeIIO(CH3COO6(H2O3]·2H2O (FeAc1, μ3-oxo trinuclear iron(III acetate, [Fe3O(CH3COO6(H2O3]NO3∙4H2O (FeAc2, iron furoate, [Fe3O(C4H3OCOO6(CH3OH3]NO3∙2CH3OH (FeF, iron chromium furoate, FeCr2O(C4H3OCOO6(CH3OH3]NO3∙2CH3OH (FeCrF, and an iron complex with an original macromolecular ligand (FePAZ were used as precursors for the corresponding oxide nanoparticles. Five series of nanoparticle samples were prepared employing either a classical thermal pathway (i.e., thermal decomposition in solution, solvothermal method, dry thermal decomposition/calcination or using a nonconventional energy source (i.e., microwave or ultrasonic treatment to convert precursors into iron oxides. The resulting materials were structurally characterized by wide-angle X-ray diffraction and Fourier transform infrared, Raman, energy-dispersive X-ray, and X-ray fluorescence spectroscopies, as well as thermogravimetric analysis. The morphology was characterized by transmission electron microscopy, atomic force microscopy and dynamic light scattering. The parameters were varied within each route to fine tune the size and shape of the formed nanoparticles.

Liquid Phase Plasma Synthesis of Iron Oxide/Carbon Composite as Dielectric Material for Capacitor

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Heon Lee

2014-01-01

Full Text Available Iron oxide/carbon composite was synthesized using a liquid phase plasma process to be used as the electrode of supercapacitor. Spherical iron oxide nanoparticles with the size of 5~10 nm were dispersed uniformly on carbon powder surface. The specific capacitance of the composite increased with increasing quantity of iron oxide precipitate on the carbon powder up to a certain quantity. When the quantity of the iron oxide precipitate exceeds the threshold, however, the specific capacitance was rather reduced by the addition of precipitate. The iron oxide/carbon composite containing an optimum quantity (0.33 atomic % of iron oxide precipitate exhibited the smallest resistance and the largest initial resistance slope.

Acidithrix ferrooxidans gen. nov., sp. nov.; a filamentous and obligately heterotrophic, acidophilic member of the Actinobacteria that catalyzes dissimilatory oxido-reduction of iron.

Science.gov (United States)

Jones, Rose M; Johnson, D Barrie

2015-01-01

A novel acidophilic member of the phylum Actinobacteria was isolated from an acidic stream draining an abandoned copper mine in north Wales. The isolate (PY-F3) was demonstrated to be a heterotroph that catalyzed the oxidation of ferrous iron (but not of sulfur or hydrogen) under aerobic conditions, and the reduction of ferric iron under micro-aerobic and anaerobic conditions. PY-F3 formed long entangled filaments of cells (>50 μm long) during active growth phases, though these degenerated into smaller fragments and single cells in late stationary phase. Although isolate PY-F3 was not observed to grow below pH 2.0 and 10 °C, harvested biomass was found to oxidize ferrous iron at relatively fast rates at pH 1.5 and 5 °C. Phylogenetic analysis, based on comparisons of 16S rRNA gene sequences, showed that isolate PY-F3 has 91-93% gene similarity to those of the four classified genera and species of acidophilic Actinobacteria, and therefore is a representative of a novel genus. The binomial Acidithrix ferrooxidans is proposed for this new species, with PY-F3 as the designated type strain (=DSM 28176(T), =JCM 19728(T)). Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Underestimation of phosphorus fraction change in the supernatant after phosphorus adsorption onto iron oxides and iron oxide-natural organic matter complexes.

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Yan, Jinlong; Jiang, Tao; Yao, Ying; Wang, Jun; Cai, Yuanli; Green, Nelson W; Wei, Shiqiang

2017-05-01

The phosphorus (P) fraction distribution and formation mechanism in the supernatant after P adsorption onto iron oxides and iron oxide-humic acid (HA) complexes were analyzed using the ultrafiltration method in this study. With an initial P concentration of 20mg/L (I=0.01mol/L and pH=7), it was shown that the colloid (1kDa-0.45μm) component of P accounted for 10.6%, 11.6%, 6.5%, and 4.0% of remaining total P concentration in the supernatant after P adsorption onto ferrihydrite (FH), goethite (GE), ferrihydrite-humic acid complex (FH-HA), goethite-humic acid complex (GE-HA), respectively. The oxide aggregates was the main mechanism for the formation of the colloid P in the supernatant. And colloidal adsorbent particles co-existing in the supernatant were another important reason for it. Additionally, dissolve organic matter dissolved from iron oxide-HA complexes could occupy large adsorption sites of colloidal iron causing less colloid P in the supernatant. Ultimately, we believe that the findings can provide a new way to deeply interpret the geochemical cycling of P, even when considering other contaminants such as organic pollutants, heavy metal ions, and arsenate at the sediment/soil-water interface in the real environment. Copyright © 2016. Published by Elsevier B.V.

Dextran-modified iron oxide nanoparticles

Czech Academy of Sciences Publication Activity Database

Hradil, Jiří; Pisarev, A. G.; Babič, Michal; Horák, Daniel

2007-01-01

Roč. 5, 1-2 (2007), s. 162-168 ISSN 1672-2515 R&D Projects: GA ČR GA203/05/2256 Institutional research plan: CEZ:AV0Z40500505 Keywords : iron oxide * nanoparticles * dextran Subject RIV: CD - Macromolecular Chemistry

Adsorption of trace elements of radionuclides on hydrous iron oxides

International Nuclear Information System (INIS)

Music, S.; Ristic, M.

1988-01-01

Factors that influence the adsorption of trace elements or radionuclides on hydrous iron oxides were investigated. The adsorption of monovalent cations (Cs + , Rb + ) on hydrous iron oxides is not strongly pH-dependent and it can be regarded as nonspecific. On the other hand, the adsorption of Ag + , divalent cations (Zn 2+ , Cd 2+ , Mn 2+ , Sr 2+ ) or trivalent cations (Cr 3+ , La 3+ , Ce 3+ , Eu 3+ , Gd 3+ , Er 3+ , Yb 3+ ) is strongly pH-dependent. The regularities of the adsorption of these cations on hydrous iron oxides are discussed. The differences in the adsorption behaviour of some divalent and trivalent cations are also explained. Freshly precipitated iron(III) hydroxide can be used for the decontamination of radionuclides from low-level waste solutions. However, the efficacy of decontamination depends on the oxidation state and the chemical properties of radionuclides. (author) 40 refs.; 9 figs

Linear-chain assemblies of iron oxide nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Dhak, Prasanta; Kim, Min-Kwan; Lee, Jae Hyeok; Kim, Miyoung; Kim, Sang-Koog, E-mail: sangkoog@snu.ac.kr

2017-07-01

Highlights: • Hydrothermal synthesis of pure phase 200 nm Fe{sub 3}O{sub 4} nanoparticles. • Studies of linear-chain assemblies of iron oxide nanosphere by FESEM. • Micromagnetic simulations showed the presence of 3D vortex states. • The B.E. for different numbers of particles in linear chain assemblies were calculated. - Abstract: We synthesized iron oxide nanoparticles using a simple hydrothermal approach and found several types of segments of their linear-chain self-assemblies as observed by field emission scanning electron microscopy. X-ray diffraction and transmission electron microscopy measurements confirm a well-defined single-phase FCC structure. Vibrating sample magnetometry measurements exhibit a ferromagnetic behavior. Micromagnetic numerical simulations show magnetic vortex states in the nanosphere model. Also, calculations of binding energies for different numbers of particles in the linear-chain assemblies explain a possible mechanism responsible for the self-assemblies of segments of the linear chains of nanoparticles. This work offers a step towards linear-chain self-assemblies of iron oxide nanoparticles and the effect of magnetic vortex states in individual nanoparticles on their binding energy.

Elucidating the role of ferrous ion cocatalyst in enhancing dilute acid pretreatment of lignocellulosic biomass

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Wei Hui

2011-11-01

Full Text Available Abstract Background Recently developed iron cocatalyst enhancement of dilute acid pretreatment of biomass is a promising approach for enhancing sugar release from recalcitrant lignocellulosic biomass. However, very little is known about the underlying mechanisms of this enhancement. In the current study, our aim was to identify several essential factors that contribute to ferrous ion-enhanced efficiency during dilute acid pretreatment of biomass and to initiate the investigation of the mechanisms that result in this enhancement. Results During dilute acid and ferrous ion cocatalyst pretreatments, we observed concomitant increases in solubilized sugars in the hydrolysate and reducing sugars in the (insoluble biomass residues. We also observed enhancements in sugar release during subsequent enzymatic saccharification of iron cocatalyst-pretreated biomass. Fourier transform Raman spectroscopy showed that major peaks representing the C-O-C and C-H bonds in cellulose are significantly attenuated by iron cocatalyst pretreatment. Imaging using Prussian blue staining indicated that Fe2+ ions associate with both cellulose/xylan and lignin in untreated as well as dilute acid/Fe2+ ion-pretreated corn stover samples. Analyses by scanning electron microscopy and transmission electron microscopy revealed structural details of biomass after dilute acid/Fe2+ ion pretreatment, in which delamination and fibrillation of the cell wall were observed. Conclusions By using this multimodal approach, we have revealed that (1 acid-ferrous ion-assisted pretreatment increases solubilization and enzymatic digestion of both cellulose and xylan to monomers and (2 this pretreatment likely targets multiple chemistries in plant cell wall polymer networks, including those represented by the C-O-C and C-H bonds in cellulose.

Iron-Tolerant Cyanobacteria: Ecophysiology and Fingerprinting

Science.gov (United States)

Brown, I. I.; Mummey, D.; Lindsey, J.; McKay, D. S.

2006-01-01

Although the iron-dependent physiology of marine and freshwater cyanobacterial strains has been the focus of extensive study, very few studies dedicated to the physiology and diversity of cyanobacteria inhabiting iron-depositing hot springs have been conducted. One of the few studies that have been conducted [B. Pierson, 1999] found that cyanobacterial members of iron depositing bacterial mat communities might increase the rate of iron oxidation in situ and that ferrous iron concentrations up to 1 mM significantly stimulated light dependent consumption of bicarbonate, suggesting a specific role for elevated iron in photosynthesis of cyanobacteria inhabiting iron-depositing hot springs. Our recent studies pertaining to the diversity and physiology of cyanobacteria populating iron-depositing hot springs in Great Yellowstone area (Western USA) indicated a number of different isolates exhibiting elevated tolerance to Fe(3+) (up to 1 mM). Moreover, stimulation of growth was observed with increased Fe(3+) (0.02-0.4 mM). Molecular fingerprinting of unialgal isolates revealed a new cyanobacterial genus and species Chroogloeocystis siderophila, an unicellular cyanobacterium with significant EPS sheath harboring colloidal Fe(3+) from iron enriched media. Our preliminary data suggest that some filamentous species of iron-tolerant cyanobacteria are capable of exocytosis of iron precipitated in cytoplasm. Prior to 2.4 Ga global oceans were likely significantly enriched in soluble iron [Lindsay et al, 2003], conditions which are not conducive to growth of most contemporary oxygenic cyanobacteria. Thus, iron-tolerant CB may have played important physiological and evolutionary roles in Earths history.

Microbial iron mats at the Mid-Atlantic Ridge and evidence that Zetaproteobacteria may be restricted to iron-oxidizing marine systems.

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Jarrod J Scott

Full Text Available Chemolithoautotrophic iron-oxidizing bacteria play an essential role in the global iron cycle. Thus far, the majority of marine iron-oxidizing bacteria have been identified as Zetaproteobacteria, a novel class within the phylum Proteobacteria. Marine iron-oxidizing microbial communities have been found associated with volcanically active seamounts, crustal spreading centers, and coastal waters. However, little is known about the presence and diversity of iron-oxidizing communities at hydrothermal systems along the slow crustal spreading center of the Mid-Atlantic Ridge. From October to November 2012, samples were collected from rust-colored mats at three well-known hydrothermal vent systems on the Mid-Atlantic Ridge (Rainbow, Trans-Atlantic Geotraverse, and Snake Pit using the ROV Jason II. The goal of these efforts was to determine if iron-oxidizing Zetaproteobacteria were present at sites proximal to black smoker vent fields. Small, diffuse flow venting areas with high iron(II concentrations and rust-colored microbial mats were observed at all three sites proximal to black smoker chimneys. A novel, syringe-based precision sampler was used to collect discrete microbial iron mat samples at the three sites. The presence of Zetaproteobacteria was confirmed using a combination of 16S rRNA pyrosequencing and single-cell sorting, while light micros-copy revealed a variety of iron-oxyhydroxide structures, indicating that active iron-oxidizing communities exist along the Mid-Atlantic Ridge. Sequencing analysis suggests that these iron mats contain cosmopolitan representatives of Zetaproteobacteria, but also exhibit diversity that may be uncommon at other iron-rich marine sites studied to date. A meta-analysis of publically available data encompassing a variety of aquatic habitats indicates that Zetaproteobacteria are rare if an iron source is not readily available. This work adds to the growing understanding of Zetaproteobacteria ecology and suggests

Chronic Iron Limitation Confers Transient Resistance to Oxidative Stress in Marine Diatoms.

Science.gov (United States)

Graff van Creveld, Shiri; Rosenwasser, Shilo; Levin, Yishai; Vardi, Assaf

2016-10-01

Diatoms are single-celled, photosynthetic, bloom-forming algae that are responsible for at least 20% of global primary production. Nevertheless, more than 30% of the oceans are considered "ocean deserts" due to iron limitation. We used the diatom Phaeodactylum tricornutum as a model system to explore diatom's response to iron limitation and its interplay with susceptibility to oxidative stress. By analyzing physiological parameters and proteome profiling, we defined two distinct phases: short-term (chronic (>5 d, phase II) iron limitation. While at phase I no significant changes in physiological parameters were observed, molecular markers for iron starvation, such as Iron Starvation Induced Protein and flavodoxin, were highly up-regulated. At phase II, down-regulation of numerous iron-containing proteins was detected in parallel to reduction in growth rate, chlorophyll content, photosynthetic activity, respiration rate, and antioxidant capacity. Intriguingly, while application of oxidative stress to phase I and II iron-limited cells similarly oxidized the reduced glutathione (GSH) pool, phase II iron limitation exhibited transient resistance to oxidative stress, despite the down regulation of many antioxidant proteins. By comparing proteomic profiles of P. tricornutum under iron limitation and metatranscriptomic data of an iron enrichment experiment conducted in the Pacific Ocean, we propose that iron-limited cells in the natural environment resemble the phase II metabolic state. These results provide insights into the trade-off between optimal growth rate and susceptibility to oxidative stress in the response of diatoms to iron quota in the marine environment. © 2016 American Society of Plant Biologists. All Rights Reserved.

Dominance of sulfur-fueled iron oxide reduction in low-sulfate freshwater sediments.

Science.gov (United States)

Hansel, Colleen M; Lentini, Chris J; Tang, Yuanzhi; Johnston, David T; Wankel, Scott D; Jardine, Philip M

2015-11-01

A central tenant in microbial biogeochemistry is that microbial metabolisms follow a predictable sequence of terminal electron acceptors based on the energetic yield for the reaction. It is thereby oftentimes assumed that microbial respiration of ferric iron outcompetes sulfate in all but high-sulfate systems, and thus sulfide has little influence on freshwater or terrestrial iron cycling. Observations of sulfate reduction in low-sulfate environments have been attributed to the presumed presence of highly crystalline iron oxides allowing sulfate reduction to be more energetically favored. Here we identified the iron-reducing processes under low-sulfate conditions within columns containing freshwater sediments amended with structurally diverse iron oxides and fermentation products that fuel anaerobic respiration. We show that despite low sulfate concentrations and regardless of iron oxide substrate (ferrihydrite, Al-ferrihydrite, goethite, hematite), sulfidization was a dominant pathway in iron reduction. This process was mediated by (re)cycling of sulfur upon reaction of sulfide and iron oxides to support continued sulfur-based respiration--a cryptic sulfur cycle involving generation and consumption of sulfur intermediates. Although canonical iron respiration was not observed in the sediments amended with the more crystalline iron oxides, iron respiration did become dominant in the presence of ferrihydrite once sulfate was consumed. Thus, despite more favorable energetics, ferrihydrite reduction did not precede sulfate reduction and instead an inverse redox zonation was observed. These findings indicate that sulfur (re)cycling is a dominant force in iron cycling even in low-sulfate systems and in a manner difficult to predict using the classical thermodynamic ladder.

Evaluation of tumoral enhancement by superparamagnetic iron oxide particles: comparative studies with ferumoxtran and anionic iron oxide nanoparticles

International Nuclear Information System (INIS)

Brillet, P-Y.; Gazeau, F.; Luciani, A.; Bessoud, B.; Cuenod, C.-A.; Siauve, N.; Pons, J.-N.; Poupon, J.; Clement, O.

2005-01-01

This study was designed to compare tumor enhancement by superparamagnetic iron oxide particles, using anionic iron oxide nanoparticles (AP) and ferumoxtran. In vitro, relaxometry and media with increasing complexity were used to assess the changes in r2 relaxivity due to cellular internalization. In vivo, 26 mice with subcutaneously implanted tumors were imaged for 24 h after injection of particles to describe kinetics of enhancement using T1 spin echo, T2 spin echo, and T2 fast spin echo sequences. In vitro, the r2 relaxivity decreased over time (0-4 h) when AP were uptaken by cells. The loss of r2 relaxivity was less pronounced with long (Hahn Echo) than short (Carr-Purcell-Meiboom-Gill) echo time sequences. In vivo, our results with ferumoxtran showed an early T2 peak (1 h), suggesting intravascular particles and a second peak in T1 (12 h), suggesting intrainterstitial accumulation of particles. With AP, the late peak (24 h) suggested an intracellular accumulation of particles. In vitro, anionic iron oxide nanoparticles are suitable for cellular labeling due to a high cellular uptake. Conversely, in vivo, ferumoxtran is suitable for passive targeting of tumors due to a favorable biodistribution. (orig.)

Mechanism of growth, composition and structure of oxide films formed on ferrous alloys in molten salt electrolytes - a review

International Nuclear Information System (INIS)

Tzvetkoff, Tz.; Kolchakov, J.

2004-01-01

The growth kinetics, chemical composition and structure of scales formed during corrosion of Fe and its alloys in molten salts are reviewed. Special attention is paid to the effect of the composition of the molten salt mixture and the gas atmosphere on the stability and protective ability of corrosion layers. First, the thermodynamical background of the corrosion and oxidation of Fe-base engineering materials in molten salt media is briefly commented. A concise review of the growth kinetics of passivating oxide films is also presented. These two introductory chapters serve as a guide for the extensive survey of the growth mechanism, nature and properties of oxide and related scales on ferrous alloys in a range of molten electrolytes - chlorides, nitrates, sulphates, carbonates, hydroxides and mixtures thereof in gas atmospheres containing O 2 , CO 2 , SO 2 , SO 3 and HCl

Water clustering on nanostructured iron oxide films

DEFF Research Database (Denmark)

Merte, Lindsay Richard; Bechstein, Ralf; Peng, G.

2014-01-01

, but it is not well-understood how these hydroxyl groups and their distribution on a surface affect the molecular-scale structure at the interface. Here we report a study of water clustering on a moire-structured iron oxide thin film with a controlled density of hydroxyl groups. While large amorphous monolayer...... islands form on the bare film, the hydroxylated iron oxide film acts as a hydrophilic nanotemplate, causing the formation of a regular array of ice-like hexameric nanoclusters. The formation of this ordered phase is localized at the nanometre scale; with increasing water coverage, ordered and amorphous...

Conflitos ambientais: uma análise da assimetria de poder entre os atores sociais envolvidos no caso do Mineroduto da Ferrous / Environmental conflict: an analysis of power asymmetry between social actors involved in the case of Ferrous Pipeline

Directory of Open Access Journals (Sweden)

Dayane Rouse Neves Sousa

2015-12-01

Full Text Available This work intends to present the environmental conflict initiated due to the installation of pipeline Ferrous Ressources S / A, in the micro region of Viçosa-MG, building an analysis of the positioning of the main social actors involved, as well as their respective relations of power. Thepipeline of Ferrous will connect the complex Beam Mine in Congonhas-MG, the port of Ferrous Ressources in Presidente Kennedy-ES in order to export iron ore. To do so, were used as methodological procedures: bibliographical research; document analysis; semi-structured interviews with different actors; and follow-up meetings of the Popular Campaign Against the Water and Pipeline Ferrous, public hearings and demonstrations taken place in the Viçosa. Furthermore, there was monitoring of the pipeline discussion in local newspapers and on blogs. Thus, this study demonstrated that the Ferrous company, which owns high economic and symbolic power, assumes the role of dominating the conflict. On the other hand, those affected and social movements against the construction of the project, are sometimes in the role of dominated, leaving them to articulate strategies of resistance to delay / stop the construction of the pipeline. The state, in turn, assumes different roles in this context, demonstrating thereby weakness in mediation and conflict management established by pipeline Ferrous mainly in the micro region of Viçosa-MG.

The detection of HBV DNA with gold-coated iron oxide nanoparticle gene probes

International Nuclear Information System (INIS)

Xi Dong; Luo Xiaoping; Lu Qianghua; Yao Kailun; Liu Zuli; Ning Qin

2008-01-01

Gold-coated iron oxide nanoparticle Hepatitis B virus (HBV) DNA probes were prepared, and their application for HBV DNA measurement was studied. Gold-coated iron oxide nanoparticles were prepared by the citrate reduction of tetra-chloroauric acid in the presence of iron oxide nanoparticles which were added as seeds. With a fluorescence-based method, the maximal surface coverage of hexaethiol 30-mer oligonucleotides and the maximal percentage of hybridization strands on gold-coated iron oxide nanoparticles were (120 ± 8) oligonucleotides per nanoparticle, and (14 ± 2%), respectively, which were comparable with those of (132 ± 10) and (22 ± 3%) in Au nanoparticle groups. Large network aggregates were formed when gold-coated iron oxide nanoparticle HBV DNA gene probe was applied to detect HBV DNA molecules as evidenced by transmission electron microscopy and the high specificity was verified by blot hybridization. Our results further suggested that detecting DNA with iron oxide nanoparticles and magnetic separator was feasible and might be an alternative effective method

Effect of bicarbonate on iron-mediated oxidation of low-density lipoprotein

Science.gov (United States)

Arai, Hirofumi; Berlett, Barbara S.; Chock, P. Boon; Stadtman, Earl R.

2005-07-01

Oxidation of low-density lipoprotein (LDL) may play an important role in atherosclerosis. We studied the effects of bicarbonate/CO2 and phosphate buffer systems on metal ion-catalyzed oxidation of LDL to malondialdehyde (MDA) and to protein carbonyl and MetO derivatives. Our results revealed that LDL oxidation in mixtures containing free iron or heme derivatives was much greater in bicarbonate/CO2 compared with phosphate buffer. However, when copper was substituted for iron in these mixtures, the rate of LDL oxidation in both buffers was similar. Iron-catalyzed oxidation of LDL was highly sensitive to inhibition by phosphate. Presence of 0.3-0.5 mM phosphate, characteristic of human serum, led to 30-40% inhibition of LDL oxidation in bicarbonate/CO2 buffer. Iron-catalyzed oxidation of LDL to MDA in phosphate buffer was inhibited by increasing concentrations of albumin (10-200 μM), whereas MDA formation in bicarbonate/CO2 buffer was stimulated by 10-50 μM albumin but inhibited by higher concentrations. However, albumin stimulated the oxidation of LDL proteins to carbonyl derivatives at all concentrations examined in both buffers. Conversion of LDL to MDA in bicarbonate/CO2 buffer was greatly stimulated by ADP, ATP, and EDTA but only when EDTA was added at a concentration equal to that of iron. At higher than stoichiometric concentrations, EDTA prevented oxidation of LDL. Results of these studies suggest that interactions between bicarbonate and iron or heme derivatives leads to complexes with redox potentials that favor the generation of reactive oxygen species and/or to the generation of highly reactive CO2 anion or bicarbonate radical that facilitates LDL oxidation. Freely available online through the PNAS open access option.Abbreviations: LDL, low-density lipoprotein; MDA, malondialdehyde; MetO, methionine sulfoxide.

Enhanced reductive dechlorination of DDT in an anaerobic system of dissimilatory iron-reducing bacteria and iron oxide

International Nuclear Information System (INIS)

Li, F.B.; Li, X.M.; Zhou, S.G.; Zhuang, L.; Cao, F.; Huang, D.Y.; Xu, W.; Liu, T.X.; Feng, C.H.

2010-01-01

The transformation of DDT was studied in an anaerobic system of dissimilatory iron-reducing bacteria (Shewanella decolorationis S12) and iron oxide (α-FeOOH). The results showed that S. decolorationis could reduce DDT into DDD, and DDT transformation rate was accelerated by the presence of α-FeOOH. DDD was observed as the primary transformation product, which was demonstrated to be transformed in the abiotic system of Fe 2+ + α-FeOOH and the system of DIRB + α-FeOOH. The intermediates of DDMS and DBP were detected after 9 months, likely suggesting that reductive dechlorination was the main dechlorination pathway of DDT in the iron-reducing system. The enhanced reductive dechlorination of DDT was mainly due to biogenic Fe(II) sorbed on the surface of α-FeOOH, which can serve as a mediator for the transformation of DDT. This study demonstrated the important role of DIRB and iron oxide on DDT and DDD transformation under anaerobic iron-reducing environments. - This is the first case reporting the reductive dechlorination of DDT in an anaerobic system of dissimilatory iron-reducing bacteria and iron oxide.

Enhanced reductive dechlorination of DDT in an anaerobic system of dissimilatory iron-reducing bacteria and iron oxide

Energy Technology Data Exchange (ETDEWEB)

Li, F.B., E-mail: cefbli@soil.gd.c [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Li, X.M. [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Zhou, S.G.; Zhuang, L. [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Cao, F. [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Huang, D.Y.; Xu, W.; Liu, T.X. [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Feng, C.H. [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China)

2010-05-15

The transformation of DDT was studied in an anaerobic system of dissimilatory iron-reducing bacteria (Shewanella decolorationis S12) and iron oxide (alpha-FeOOH). The results showed that S. decolorationis could reduce DDT into DDD, and DDT transformation rate was accelerated by the presence of alpha-FeOOH. DDD was observed as the primary transformation product, which was demonstrated to be transformed in the abiotic system of Fe{sup 2+} + alpha-FeOOH and the system of DIRB + alpha-FeOOH. The intermediates of DDMS and DBP were detected after 9 months, likely suggesting that reductive dechlorination was the main dechlorination pathway of DDT in the iron-reducing system. The enhanced reductive dechlorination of DDT was mainly due to biogenic Fe(II) sorbed on the surface of alpha-FeOOH, which can serve as a mediator for the transformation of DDT. This study demonstrated the important role of DIRB and iron oxide on DDT and DDD transformation under anaerobic iron-reducing environments. - This is the first case reporting the reductive dechlorination of DDT in an anaerobic system of dissimilatory iron-reducing bacteria and iron oxide.

Fish Proteins as Targets of Ferrous-Catalyzed Oxidation: Identification of Protein Carbonyls by Fluorescent Labeling on Two-Dimensional Gels and MALDI-TOF/TOF Mass Spectrometry

DEFF Research Database (Denmark)

Pazos, Manuel; da Rocha, Angela Pereira; Roepstorff, Peter

2011-01-01

Protein oxidation in fish meat is considered to affect negatively the muscle texture. An important source of free radicals taking part in this process is Fenton's reaction dependent on ferrous ions present in the tissue. The aim of this study was to investigate the susceptibility of cod muscle pr...

Activation and detoxification of UICC crocidolite: the effect of conversion of oxidation state of iron on the toxicity of the fibres

International Nuclear Information System (INIS)

Gulumian, M.; Waard, H. de; Pollak, H.

1993-01-01

Detoxification of crocidolite, an asbestiform riebeckite with a coating of ferric salt, converted some of the ferrous ions into ferric ions and therefore decreased the activity of the fibres to catalyse the reduction of oxygen and peroxide. The H 2 -activation of crocidolite fibres on the other hand, changed some of the ferric ions into ferrous ions and therefore increased the capacity of the fibres to catalyse these two reactions. Moessbauer spectroscopy (MS) combined with wet chemical analysis, X-ray diffraction, X-ray fluorescence, and neutron activation analysis enabled us to determine the site occupancies of iron and magnesium in UICC (Union Internationale Contre le Cancer) crocidolite and the ratio of the recoil-free fractions f(Fe 2+ )/f(Fe 3+ )=0.86±0.07. These results and further MS studies with detoxified and activated fibres explained the effect of the two processes on the activity of iron in the fibres. (orig.)

The magnetic and oxidation behavior of bare and silica-coated iron oxide nanoparticles synthesized by reverse co-precipitation of ferrous ion (Fe.sup.2+./sup.) in ambient atmosphere

Czech Academy of Sciences Publication Activity Database

Mahmed, N.; Heczko, Oleg; Lančok, Adriana; Hannula, S.-P.

2014-01-01

Roč. 353, MAR (2014), s. 15-22 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GAP107/11/0391 Institutional support: RVO:68378271 Keywords : reverseco-precipitation * ferrousion * magnetite * Mössbauer * silica Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.970, year: 2014 http://www.sciencedirect.com/science/article/pii/S0304885313007336

Biological iron oxidation by Gallionella spp. in drinking water production under fully aerated conditions.

Science.gov (United States)

de Vet, W W J M; Dinkla, I J T; Rietveld, L C; van Loosdrecht, M C M

2011-11-01

Iron oxidation under neutral conditions (pH 6.5-8) may be a homo- or heterogeneous chemically- or a biologically-mediated process. The chemical oxidation is supposed to outpace the biological process under slightly alkaline conditions (pH 7-8). The iron oxidation kinetics and growth of Gallionella spp. - obligatory chemolithotrophic iron oxidizers - were assessed in natural, organic carbon-containing water, in continuous lab-scale reactors and full-scale groundwater trickling filters in the Netherlands. From Gallionella cell numbers determined by qPCR, balances were made for all systems. The homogeneous chemical iron oxidation occurred in accordance with the literature, but was retarded by a low water temperature (13 °C). The contribution of the heterogeneous chemical oxidation was, despite the presence of freshly formed iron oxyhydroxides, much lower than in previous studies in ultrapure water. This could be caused by the adsorption of natural organic matter (NOM) on the iron oxide surfaces. In the oxygen-saturated natural water with a pH ranging from 6.5 to 7.7, Gallionella spp. grew uninhibited and biological iron oxidation was an important, and probably the dominant, process. Gallionella growth was not even inhibited in a full-scale filter after plate aeration. From this we conclude that Gallionella spp. can grow under neutral pH and fully aerated conditions when the chemical iron oxidation is retarded by low water temperature and inhibition of the autocatalytic iron oxidation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Iron oxide/cassava starch-supported Ziegler-Natta catalysts for in situ ethylene polymerization.

Science.gov (United States)

Chancharoenrith, Sittikorn; Kamonsatikul, Choavarit; Namkajorn, Montree; Kiatisevi, Supavadee; Somsook, Ekasith

2015-03-06

Iron oxide nanoparticles were used as supporters for in situ polymerization to produce polymer nanocomposites with well-dispersed fillers in polymer matrix. Iron oxide could be sustained as colloidal solutions by cassava starch to produce a good dispersion of iron oxide in the matrix. New supports based on iron oxide/cassava starch or cassava starch for Ziegler-Natta catalysts were utilized as heterogeneous supporters for partially hydrolyzed triethylaluminum. Then, TiCl4 was immobilized on the supports as catalysts for polymerization of ethylene. High-density polyethylene (HDPE) composites were obtained by the synthesized catalysts. A good dispersion of iron oxide/cassava starch particles was observed in the synthesized polymer matrix promoting to good mechanical properties of HDPE. Copyright © 2014 Elsevier Ltd. All rights reserved.

Composition of MBE-grown iron oxide films

NARCIS (Netherlands)

Voogt, F.C; Hibma, T; Smulders, P.J M; Niesen, L

A wide range of iron oxides have been grown epitaxially on MgO(100) substrates using a dual beam technique in which the deposited iron is oxidised by a beam of NO2 particles. At high fluxes magnetite (Fe3-deltaO4) phases with compositions between near-stoichiometric magnetite (Fe3O4, delta = 0) and

Body iron is a contributor to oxidative damage of DNA

DEFF Research Database (Denmark)

Tuomainen, Tomi-Pekka; Loft, Steffen; Nyyssönen, Kristiina

2007-01-01

The transition metal iron is catalytically highly active in vitro, and not surprisingly, body iron has been suggested to promote oxidative stress in vivo. In the current analysis we studied the association of serum ferritin concentration and serum soluble transferrin receptor concentration.......17 (95% CI 0.08-0.26, P = 0.001), and serum soluble transferrin receptor to ferritin concentration ratio (TfR/ferritin) predicted the excretion rate at B = - 0.13 (95% CI - 0.21 to - 0.05, P = 0.002). Our data suggest that body iron contributes to excess oxidative stress already at non-iron overload...

Iron Oxide as an MRI Contrast Agent for Cell Tracking

Science.gov (United States)

Korchinski, Daniel J.; Taha, May; Yang, Runze; Nathoo, Nabeela; Dunn, Jeff F.

2015-01-01

Iron oxide contrast agents have been combined with magnetic resonance imaging for cell tracking. In this review, we discuss coating properties and provide an overview of ex vivo and in vivo labeling of different cell types, including stem cells, red blood cells, and monocytes/macrophages. Furthermore, we provide examples of applications of cell tracking with iron contrast agents in stroke, multiple sclerosis, cancer, arteriovenous malformations, and aortic and cerebral aneurysms. Attempts at quantifying iron oxide concentrations and other vascular properties are examined. We advise on designing studies using iron contrast agents including methods for validation. PMID:26483609

Evaluation of the properties of iron oxide-filled castor oil polyurethane

OpenAIRE

Mussatti, Eleonora; Merlini, Claudia; Barra, Guilherme Mariz de Oliveira; Güths, Saulo; Oliveira, Antonio Pedro Novaes de; Siligardi, Cristina

2012-01-01

The aim of this study was to obtain and evaluate the electrical, thermal and mechanical properties of iron oxide-filled castor oil polyurethane (PU/Fe2O3). The iron oxide used in this study was a residue derived from the steel pickling process of a Brazilian steel rolling industry. Polymeric composites with different iron oxide volume fractions (2.5, 5.0, 7.5, 10.0 and 12.5%) were prepared through the casting process followed by compression molding at room temperature. The composites were ana...

DLVO and XDLVO calculations for bacteriophage MS2 adhesion to iron oxide particles.

Science.gov (United States)

Park, Jeong-Ann; Kim, Song-Bae

2015-10-01

In this study, batch experiments were performed to examine the adhesion of bacteriophage MS2 to three iron oxide particles (IOP1, IOP2 and IOP3) with different particle properties. The characteristics of MS2 and iron oxides were analyzed using various techniques to construct the classical DLVO and XDLVO potential energy profiles between MS2 and iron oxides. X-ray diffractometry peaks indicated that IOP1 was mainly composed of maghemite (γ-Fe2O3), but also contained some goethite (α-FeOOH). IOP2 was composed of hematite (α-Fe2O3) and IOP3 was composed of iron (Fe), magnetite (Fe3O4) and iron oxide (FeO). Transmission electron microscope images showed that the primary particle size of IOP1 (γ-Fe2O3) was 12.3±4.1nm. IOP2 and IOP3 had primary particle sizes of 167±35nm and 484±192nm, respectively. A surface angle analyzer demonstrated that water contact angles of IOP1, IOP2, IOP3 and MS2 were 44.83, 64.00, 34.33 and 33.00°, respectively. A vibrating sample magnetometer showed that the magnetic saturations of IOP1, IOP2 and IOP3 were 176.87, 17.02 and 946.85kA/m, respectively. Surface potentials measured in artificial ground water (AGW; 0.075mM CaCl2, 0.082mM MgCl2, 0.051mM KCl, and 1.5mM NaHCO3; pH7.6) indicated that iron oxides and MS2 were negatively charged in AGW (IOP1=-0.0185V; IOP2=-0.0194V; IOP3=-0.0301V; MS2=-0.0245V). Batch experiments demonstrated that MS2 adhesion to iron oxides was favorable in the order of IOP1>IOP2>IOP3. This tendency was well predicted by the classical DLVO model. In the DLVO calculations, both the sphere-plate and sphere-sphere geometries predicted the same trend of MS2 adhesion to iron oxides. Additionally, noticeable differences were not found between the DLVO and XDLVO interaction energy profiles, indicating that hydrophobic interactions did not play a major role; electrostatic interactions, however, did influence MS2 adhesion to iron oxides. Furthermore, the aggregation of iron oxides was investigated with a modified XDLVO