Elemental Iron Powders Research Articles

The Poor Bioavailability of Elemental Iron in Corn Masa Flour Is Not Affected by Disodium EDTA

The most sustainable way to eradicate iron deficiency is through food fortification. Elemental iron powders are commonly utilized as fortificants due to their low cost and few sensory problems. However, their bioavailability is unknown. Our goals were to measure the bioavailability of elemental iron in Mexican style corn masa flour tortillas and to evaluate the effects of Na(2)EDTA. We used a stable isotope of H(2)-reduced iron powder, with and without Na(2)EDTA in tortillas prepared with corn masa flour. Two groups of 5- to 7-y-old children (n = 12/group) were fed tortillas to which was added 3 mg/100 g of H(2)-reduced (58)Fe with a mean particle size of 15 micro m. In one group, Na(2)EDTA was incorporated at a ratio of 1:2 mol/mol. The next day, (57)Fe ascorbate was given as a reference dose. After 14 d, blood samples were analyzed for isotopic enrichment. When normalized to 40% absorption of the reference dose, the geometric mean (+/-range 1 SD) bioavailability of reduced iron in tortilla was 3.8% (2.7-5.3). The addition of Na(2)EDTA, tended to increase it (P = 0.18) to 5.1% (2.8-9.2). This observed low absorption was compounded by the use of iron isotopes with smaller particle size (mean diameter 15 micro m) than typical of commercial elemental iron powder (<45 micro m). We conclude that H(2)-reduced iron powder is an ineffective fortificant in corn tortillas.

Mechanical Alloying of Fe&lt;SUB&gt;25&lt;/SUB&gt;Al&lt;SUB&gt;75&amp;minus;&lt;i&gt;x&lt;/i&gt;&lt;/SUB&gt;Ti&lt;SUB&gt;&lt;i&gt;x&lt;/i&gt;&lt;/SUB&gt; Mixed Powders

Elemental aluminum, titanium and iron powders with compositions of Fe 2 5 Al 7 5 - x Ti x (x = 0, 3.75, 7.5, 11.25 and 15) were mechanical alloyed in a planetary ball mill. The transformations and thermal stabilities of milled powders were characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Supersaturated solid solutions were found in low Ti concentration (x = 0-7.5). The addition of Ti shortened the milling time for the formation of solid solution. The amorphous phases were obtained with high Ti concentration (x = 11.25 and 15). The activation enthalpies of crystallization for amorphous phases increased with Ti. The crystallization temperatures of amorphous alloys were calculated, which are in good agreement with the experimental values.

Serum iron concentration as a tool to measure relative iron absorption from elemental iron powders in man

Objective: To present a new method for measuring the relative bioavailability (RBV) of commercial elemental iron powders by investigating induced changes of serum iron concentration (S‐Fe) in relation to ferrous sulphate (FeSO4). Earlier studies have shown that in a group of subjects there is good agreement between the increase in S‐Fe and the amount of iron absorbed from a simple iron salt as FeSO4. Methods: The study included two groups of male blood donors (n=2×16 subjects) who were served three meals with an interval of approximately nine weeks between each one. In one group the meal was fortified with reduced iron, ferrous sulphate or no iron at all. In the other group the meal was fortified with electrolytic iron, ferrous sulphate or no iron. The S‐Fe increase was followed for 6 h. Studying the non‐iron meals was necessary so that the basal diurnal variation in the S‐Fe during the six hours could be measured and subtracted. Results: The mean S‐Fe increase calculated as the area under the curve (AUC) from the reduced iron (RBV=0.43) and the electrolytic iron (RBV=0.73) differed significantly from the AUC following FeSO4 (p=0.002 and p=0.021, respectively). The difference between the reduced and the electrolytic iron was also statistically significant (p=0.036). Conclusion: Measuring increases in S‐Fe could be a reliable and simple method to determine the RBV in comparative studies of elemental iron powders in relation to FeSO4.

Bioavailability of Elemental Iron Powders to Rats Is Less than Bakery-Grade Ferrous Sulfate and Predicted by Iron Solubility and Particle Surface Area

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 < 0.05) with the following rank order: Carbonyl (64%; Ferronyl, U.S.) > 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.

Kemira Metalkat Oy becomes Ecocat Oy

Different sorbents were tested in situ for their ability to reduce the concentration of Cu, Sb and Pb in drainage water from a shooting range. The sorbents tested were: Brimac® charcoal, olivine mixed with elemental iron powder, magnetite and Kemira® iron hydroxide. The mean sorption of Cu, Sb and Pb was 84%, 66%, 85% with Brimac® charcoal and 58%, 78% and 69% with Kemira® iron hydroxide. Good sorption of Cu and Pb was achieved using olivine with 5% elemental Fe powder, which resulted in a sorption of 81% and 87%, respectively. The Fe-olivine filters were less efficient in reducing the concentration of Sb, but increasing the Fe content improved Sb sorption. In periods with high concentrations of Pb, Cu and Sb in the creek, such as during precipitation, the sorbent efficacy improved. This might be due to changes in the physico-chemical form of the metals, or to a higher fraction of elements being physically retained in the form of particles or colloids.

Iron and Ascorbic Acid: Proposed Fortification Levels and Recommended Iron Compounds

An adequate supply of dietary iron during the 1st 24 mo of life is essential for preventing iron deficiency with its attendant negative effects on mental, motor and emotional development as well as later cognitive performance. Iron reserves and the small amount of highly bioavailable iron in human milk are adequate to satisfy the iron requirements of breast-fed infants of adequate birth weight for the 1st 6 mo of life. Thereafter, complementary foods, iron supplements or both are needed to meet this requirement. Complementary foods should not displace the consumption of human milk. The quantities eaten, particularly by younger infants, may therefore be quite small. As a consequence it is essential that the iron be supplied in a highly bioavailable form. This can be achieved by fortifying complementary foods with ferrous sulfate and ascorbic acid provided that the ascorbic acid is not lost during storage or meal preparation. Suggested fortification levels for ferrous sulfate and ascorbic acid for some types of complementary foods are given. The use of ferrous fumarate or an elemental iron powder instead of ferrous sulfate has not been evaluated adequately. There is a need to develop alternative strategies for improving iron bioavailability in complementary foods because it may not be possible to preserve ascorbic acid activity in many of them.

Transient liquid phase sintering of high density Fe3Al using Fe and Fe2Al5/FeAl2 powders Part 1: Experimentation and results

High density Fe3Al was produced through transient liquid phase sintering, using rapid heating rates of greater than 150 K min-1 and a mixture of prealloyed and elemental powders. Prealloyed Fe2Al5/FeAl2 (50Fe/50Al, wt-%) powder was added to elemental iron powder in a ratio appropriate for producing an overall Fe3Al (13·87 wt-%) ratio. The heating rate, sintering time, sintering temperature, green density and powder particle size were controlled during the study. Heating rate, sintering time and powder particle size had the most significant influence upon the sintered density of the compacts. The highest sintered density of 6·12 Mg m-3 (92% of the theoretical density for Fe3Al) was achieved after 15 minutes of sintering at 1350°C, using a 250 K min- 1 heating rate, 1-6 μm Fe powders and 5·66 μm alloy powders.SEM microscopy suggests that agglomerated Fe2Al5/ FeAl2 particles, which form a liquid during sintering, are responsible for a significant portion of the remaining porosity in high sintered density compacts, creating stable pores, larger than 100 μm diameter, after melting. High density was achieved by minimising the Kirkendall porosity formed during heating by unbalanced diffusion and solubility between the iron and Fe2Al5/FeAl2 components. The lower diffusion rate of aluminium in the prealloyed powder into the iron compared with elemental aluminium in iron, coupled with a fast heating rate, is expected to permit minimal iron-aluminium interdiffusion during heating so that when a liquid forms the aluminium dissolves in the iron to promote solidification at a lower aluminium content. This leads to a further reduction in porosity.

Effect of milling speed on an Fe–C–Mn system alloy prepared by mechanical alloying

Mechanical alloying (MA) of elemental iron, graphite and manganese powders consisting of Fe–7 mass% C–6 mass% Mn were carried out by using a planetary ball mill at different milling speed. The structural evolution of the MAed powders was characterized by X-ray diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscopy (SEM). The MAed powders were hot isostatic pressed (HIPed) at 100 MPa for 1 h at lower (853 K) or higher (1053 K) than the eutectoid transformation temperature A 1. The processes of amorphization, super-saturated solid solution and particle refinement are influenced by the milling speed. These processes are faster with the increase in the milling speed. The hardness and microstructure of the HIPed compacts are influenced by the morphology of the MAed powders obtained. The powders MAed at high speed has higher hardness at the HIPed compacts than the powders MAed at low speed. Since the sintering progresses well at a temperature higher than A 1 and the phase transformation of γ-Fe into fine carbide and α-Fe occurs during cooling process, the hardness of the compacts HIPed at 1053 K higher than A 1 is greater than that at 853 K lower than A 1.

The usefulness of elemental iron for cereal flour fortification: a SUSTAIN Task Force report. Sharing United States Technology to Aid in the Improvement of Nutrition.

Fortification of cereal flours may be a useful public health strategy to combat iron deficiency. Cereal flours that are used shortly after production (e.g., baking flour) can be fortified with soluble iron compounds, such as ferrous sulfate, whereas the majority of flours stored for longer periods is usually fortified with elemental iron powders to avoid unacceptable sensory changes. Elemental iron powders are less well absorbed than soluble iron compounds and they vary widely in their absorption depending on manufacturing method and physicochemical characteristics. Costs vary with powder type, but elemental iron powders are generally less expensive than ferrous sulfate. This review evaluates the usefulness of the different elemental iron powders based on results from in vitro studies, rat assays, human bioavailability studies, and efficacy studies monitoring iron status in human subjects. It concludes that, at the present time, only electrolytic iron powder can be recommended as an iron fortificant. Because it is only approximately half as well absorbed as ferrous sulfate, it should be added to provide double the amount of iron.

Reactive sintering in Fe-Co system

Low porosity powder metallurgy compacts have been manufactured from treated elemental iron and cobalt powders sintered at 1150°C under an H2(g) atmosphere. Their microstructures consist of an interconnected mixed oxide network which encapsulates both the iron and cobalt phases. The production technique employed is an innovative process termed reacto-thermitic sintering (RTS), which leads to near full density and near net shape parts utilising conventional uniaxial compaction and mesh belt furnace practices. The RTS technique relies on microscale exothermic reaction between small quantities of added elemental Al and oxides present on the surface of the bulk powder, together with the bulk powder itself. This results in the production of a transient liquid phase which freezes rapidly and consolidates the compact without slumping. In order to generate an interconnected mixed oxide network, experiments were designed such that the Al powder reacts with the cobalt and the surface of the iron powder which is artificially doped with Fe and Cr oxides.Differential thermal analysis (DTA) and energy balance calculations revealed that the Al and the oxide coating reaction does not proceed directly. Instead the main contribution to the exothermic process is the reaction between Al and Co/Fe. The system does not exhibit true RTS behaviour and the interconnected network of mixed Al, Cr, and Fe oxides is created by subsequent reaction of Co-Al and Fe-Al intermetallics with the artificial Fe-Cr oxide coating on the Fe. The microstructure obtained exhibits negligible porosity with the metallic particles on the whole fully encapsulated by the oxide.

Monterrey Workshop summary: evaluating the usefulness of elemental iron powders.

Monterrey Workshop summary: evaluating the usefulness of elemental iron powders.

Fortification: Overcoming Technical and Practical Barriers

The main barriers to successful iron fortification are the following: 1) finding an iron compound that is adequately absorbed but causes no sensory changes to the food vehicle; and 2) overcoming the inhibitory effect on iron absorption of dietary components such as phytic acid, phenolic compounds and calcium. These barriers have been successfully overcome with some food vehicles but not with others. Iron-fortified fish sauce, soy sauce, curry powder, sugar, dried milk, infant formula and cereal based complementary foods have been demonstrated to improve iron status in targeted populations. The reasons for this success include the use of soluble iron such as ferrous sulfate, the addition of ascorbic acid as an absorption enhancer or the use of NaFeEDTA to overcome the negative effect of phytic acid. In contrast, at the present time, it is not possible to guarantee a similar successful fortification of cereal flours or salt. There is considerable doubt that the elemental iron powders currently used to fortify cereal flours are adequately absorbed, and there is an urgent need to investigate their potential for improving iron status. Better absorbed alternative compounds for cereal fortification include encapsulated ferrous sulfate and NaFeEDTA, which, unlike ferrous sulfate, do not provoke fat oxidation of cereals during storage. Encapsulated compounds also offer a possibility to fortify low grade salt without causing off-colors or iodine loss. Finally, a new and useful additional approach to ensuring adequate iron absorption from cereal based complementary foods is the complete degradation of phytic acid with added phytases or by activating native cereal phytases.

Thermal stability, grain growth and structure changes of mechanically alloyed W–Ni–Fe composite during annealing

Mechanical alloying of elemental tungsten, nickel and iron powders was carried out in argon for 20 h to produce a nano-crystalline composite. By using a combination of DTA, XRD, OM and EDX analyses, systematic investigations were carried out on thermal stability, phase and microstructure changes during annealing. The results have shown, during annealing, the as-milled powder goes through stress relaxation, recovering and grain growth, precipitation of Ni, Fe phase from W supersaturated solution, amorphous phase crystallization, and a series of phase and microstructure changes. The phase and microstructure changes go through six steps. A significant grain growth occurs above 1100°C. Milling increased solubility of W in γ phase. The solubility decreases with an increase of temperature.

Sintering of elemental carbonyl iron and carbonyl nickel powder mixtures

Iron-nickel alloys with compositions ranging from pure iron to pure nickel at increments of 10 wt% have been prepared by mixing fine elemental carbonyl iron and nickel powders, and sintering at temperatures between 1200–1350°C. The addition of nickel to iron promoted densification and avoided abnormal grain growth at low concentrations. However the densification was retarded when the iron and nickel had approximately equivalent concentrations. As the concentration of nickel increased, the room temperature structures of the alloys gradually changed from α-Fe into γ-(Fe, Ni), with Fe-30 wt% Ni and Fe-40 wt%, Ni containing both phases. The relative abundance of each phase was determined by the degree of compositional homogeneity achieved in sintering.

Solid-state reactions in the Al-Fe system induced by ball milling of elemental powders

Elemental aluminium and iron powders have been mechanically alloyed in the atomic Al∶Fe ratios of 1∶1 and 1∶3. The structural evolution of the samples was followed by X-ray diffraction and differential calorimetry. Extended milling caused the formation of an almost completely disordered b c c solid solution instead of the equilibrium B2 and DO3 compounds. Upon heating to 700 °C the formation of the B2 phase was observed in the equiatomic samples and no significant variation of the long-range state of order in the iron-rich samples. Upon heating of samples pre-milled for short or intermediate times, at about 400 °C, the nucleation and growth of Al5Fe2 was observed which, upon further heating to 700 °C, transformed to the B2 phase or to the b c c solid solution, depending on the sample composition. These results suggest that the solid-state reactions proceed through diffusion of iron atoms in the aluminium layers, and that for an iron concentration in these layers below about 50 at%, the Al(Fe) solid solution could be in a metastable phase.

Processing and microhardness of bulk Cu-Fe nanocomposites

Full-density bulk nanocomposites have been developed in the immiscible Cu-Fe system through a powder metallurgy route. Elemental copper and iron powders were first mechanically alloyed to form single-phase, nanocrystalline, metastable solid solutions, Cu 100 − x Fe x (x = 0 to 100). These solid solutions were subsequently decomposed into Cu/Fe two-phase domains of various volume fractions during the hot consolidation process, forming in situ nanophase Cu-Fe composites. Full-density compacts have been produced at relatively low consolidation temperatures (< 500°C) by employing sinter forging at high applied pressure and a protective atmosphere. Such a consolidation scheme, coupled with enhanced grain size stability due to the unique microstructural evolution sequence involved, retained the grain sizes in the nanometer range for both Cu and Fe grains in the composite products. Fully dense composite specimens exhibit enhanced microhardness as compared with rule-of-mixtures predictions. This enhancement is attributed to interface strengthening at fcc-bcc interphase boundaries.

Hot hydrostatic extrusion and microstructures of mechanically alloyed Al4.9Fe4.9Ni alloy

Mechanical alloying has been used to synthesize Al4.9Fe4.9Ni powders from mixed elemental aluminum, iron and nickel powders, the mechanically-alloyed powders being consolidated by hot hydrostatic extrusion. The mechanical properties of the extruded rod were measured, and microstructures of the consolidated materials were investigated by X-ray diffraction and TEM analysis. The results show that the tensile strength increases and the elongation decreases with the increasing of the milling time, which results from the reduction of the grain size and the increasing of the volume fraction of particles in the aluminum matrix as the milling time increased. Alloys of extruded 14 h-milled powders show good strength at both room and elevated temperature. The extrusion temperature, extrusion ratio and lubricant have great effects on the properties. A mixture of graphite and glass powders as lubricant can prevent the oxidization of a cold compacted billet when the billet is clad with this lubricant before heating, the consolidated materials showing no obvious oxidation.

Metastable phases formation induced by mechanical alloying

Elemental aluminium, titanium and iron powders with compositions of Al90Ti10, Al55Ti45, Al65Ti25Fe10, respectively, were mechanically alloyed in a planetary ball mill. The sequence of phase formation was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). Various metastable phases were experimentally observed: supersaturated solid solution Al(Ti) for Al90Ti10, amorphous phase and L12-Al3Ti compound for Al55Ti45, amorphous phase and supersaturated solid solution Al(Ti,Fe) for Al65Ti25Fe10, and an fcc crystalline phase was inevitably found in those alloys. The formation of the fcc crystalline phase has been critically assessed. The results suggest that the fcc crystalline phase seems to be metastable and it cannot be solely attributed to the contamination from the milling atmosphere underthe present experimental conditions.

Comparison of ball milling of Fe/Cr powders and Fe-Cr crystalline alloy

Using the mechanical attrition technique (MA), we have prepared a Fe-Cr alloy starting with a mixture of elemental iron and chromium powders with a nominal composition of 28 at% of Fe and 72 at% of Cr. MA was also performed on solid solutions of Fe28Cr72 crystalline alloy. The Mossbauer effect of the mechanically alloyed powder from Cr and Fe metals has been compared with that from crystalline alloy.

Magnetic properties of mechanically alloyed Fe 3Sn

Amorphous 3FeSn powders have been prepared by the mechanical alloying of elemental iron and tin powders. During the milling process the FeSn 2 phase appears at first and then vanishes for a milling time over 15 h. When the milling time is increased to 30 h, the X-ray diffraction pattern of as-milled powders reveals a broad peak typical of an amorphous phase. The saturation magnetization of as-milled powders decreases with increasing milling time up to 30 h, then increases slightly over 30 h, while the coercivity exhibits an opposite tendency. Crystalline phases are obtained by annealing as-milled powders at 770–850°C for 0.5–10 h. A unique crystalline Fe 3Sn phase is formed after 2 h at a high annealing temperature (850°C) which possesses a saturation magnetization of 115 e.m.u.g −1.