Iron Strips Research Articles

In Situ Prussian Blue-Electrocatalyst Formation on Intrinsic Iron-Containing Pristine-MWCNT as a Template and Its EQCM and SECM Interrogations and Batch Injection Analysis of Hydrogen Peroxide

Herein, we report in-situ electrochemical derivatization of the intrinsic iron species in a pristine-multiwalled carbon nanotube (MWCNT) as Prussian blue (PB) modified MWCNT hybrid (MWCNT@PB) using a dilute solution of ferricyanide as a derivatization agent in pH 2 HCl-KCl solution. The PB hybrid system showed a defined redox peak at an apparent standard electrode potential, Eo’ = 0.18 V vs Ag/AgCl with an excess surface value, 1.71 × 10−10 mol cm−2. A discreet EQCM study on the electrochemical preparation of MWCNT@PB using MWCNT and ferricyanide precursors reveal the specific stripping of iron species and uptake of iron species, potassium and ferricyanide ions upon the electrochemical preparation condition. In-situ imaging of MWCNT@PB was carried out using SECM with ferricyanide as a redox mediator under a feedback-current mode. It has been identified that a mixed-potential based electrochemical reaction involving oxidative stripping of iron to iron ion species (step-1) coupled with reduction of ferricyanide to ferrocyanide (step-2) followed by a chemical interaction between the iron ion and ferricyanide (step-3) have occurred for the overall formation of MWCNT@PB hybrid. Electrocatalytic and electroanalytical performance of the MWCNT@PB hybrid towards H2O2 reduction and sensing were demonstrated by performing cyclic voltammetric, amperometric i-t and batch injection analysis.

Stepwise Separation for Calcium Recovery from an Ammonium Sulfate Leaching System

Calcium recovery from high calcium solid waste is driven by the latter’s growing environmental impact, emphasizing the need to develop a high value-added utilization approach. Inspired by our previous study, we develop a stepwise separation strategy for calcium recovery from an ammonium sulfate leaching system to efficiently remove iron and unburned carbon residue. In this study, tributyl phosphate (TBP) used as the carbon residue adsorbent for calcium recovery exhibits high selectivity and good recycling stability. Adsorption measurements show that TBP yields a superior carbon residue adsorption ability with a maximum adsorption ratio greater than 95%. Moreover, the adsorption percentage is also kept more than 90% after 10 cycles, which substantiates the good potential of TBP for reuse. Besides, the low concentration (1 mol/L) of H2SO4 provides an acidic environment, which makes TBP more feasible to be applied in carbon residue adsorption and effective iron(III) stripping. Furthermore, it is inferred from the Fourier transform infrared spectroscopy/X-ray photoelectron spectrometer and density functional theory analyses that the enhanced carbon separation performance may be ascribed to the carboxyl in carbon residue coordinated to the donor oxygen atom of TBP at the position of P–O. This work provides the foothold for further research on the recovery of calcium from industrial by-products.

Production of Pure Iron Strip Specimens by Electrodeposition from a Chloride Bath for Use in Tensile Tests

Production of Pure Iron Strip Specimens by Electrodeposition from a Chloride Bath for Use in Tensile Tests

Manufacturing of Pure Iron by Cold Rolling and Investigation for Application in Magnetic Flux Shielding.

The presented work investigates a novel method to manufacture 98.8% pure iron strips having high permeability and better saturation flux density for application in magnetic flux shielding. The proposed method uses electro-deposition and cold rolling along with intermediate annealing in a controlled environment to manufacture 0.05–0.5 mm thick pure iron strips. The presented approach is inexpensive, has better control over scaling/oxidation and requires low energy than that of the conventional methods of pure iron manufacturing by pyrometallurgical methods. Important magnetic and mechanical properties of the pure iron are investigated in the context of the application of the material in magnetic shielding. Magnetic properties of the material are investigated by following IEC60404-4 standard and toroidal coil test to determine hysteresis curve, magnetic permeability and core losses. The microstructure is investigated with an optical microscope and scanning electron microscopy to study grain size and defects after cold rolling and annealing. The properties derived from the experimental methods are used in finite element analysis to study the application of the material for static, low-frequency and high-frequency magnetic shielding. Theoretical simulation results for magnetic shielding around a current-carrying conductor and micro-electromechanical inductive sensor system are discussed. Further shielding performance of the material is compared with that of the other candidate materials, including that of Mu-metal and electrical steel. It is demonstrated that the pure iron strips manufactured in the present study can be used for magnetic shielding in the case of low-frequency applications. In the case of high-frequency applications, a conducting layer can be combined to ensure the required shielding effectiveness in the case of Class 2 applications.

Best Conditions for Extraction and Stripping of Iron from Chloridic Aqueous Medium

Pure iron is used as an additive for food and drugs to provide the human body with an important element which is iron. For this purpose, iron should be pure and in powder form, the extraction process can supply this type of iron. In this study, extraction of iron from an aqueous solution was done by cyclohexanone as an extractant. The parameters of extraction and stripping processes were studied and assessed the best values which give a high yield of separated iron from ore or any source of iron. For the preliminary study, three general parameters were studied and the best values are agitation time (10 min.), agitation speed (400 rpm), and temperature (30C). In the main study for the extraction process, there are four parameters were investigated and the optimum values are phase ratio (O/A) (1/1), iron concentration (conversely relationship), extractant concentration (proportional relationship), and normality (5 N). The best values for stripping process parameters are phase ratio(A/O) (1/2 – 1/1) and normality of strip solution (0.1 N). The extraction technique is very important in Pharmaceutical industries to produce different suitable metals associated with food and drugs. The extraction technique was detected as an appropriate method to separate iron and introduce it in pure powder form.

Use of ferric salt solutions as leaching agents of Co, Ni, Cu, Fe, and Mn from metallic alloys of spent lithium-ion batteries and separation of iron from the leaching solution

Smelting reduction of spent lithium-ion batteries (LIBs) results in metallic alloys containing Co, Ni, Cu, Fe, and Mn. In order to recover the valuable metals contained in the metallic alloys, they need to be dissolved. In this work, the mixture of Fe2(SO4)3 and FeSO4, single Fe2(SO4) and FeCl3 solutions were used as leaching agents and the effects of parameters such as ferric salt concentration, reaction temperature and time, and pulp density on the leaching of the metals were studied. The difference in the leaching percentage of the metals due to the type of the ferric solutions was insignificant. In these leaching systems, ferric and hydrogen ions act as oxidants and sulfate/bisulfate and chloride anions act as ligands. Optimal conditions for the complete leaching of metals by single ferric solutions were 0.35 mol/L Fe2(SO4)3 or 0.7 mol/L FeCl3 at 12.5 g/L pulp density for 60 min at 22oC. The addition of H2O2 to the leaching solution for the oxidation of Fe(II) to Fe(III) enhanced the selective extraction of iron over Co(II), Ni(II), Cu(II), Mn(II), and Si(IV) by D2EHPA. Stripping of iron from the loaded D2EHPA with aqua regia resulted in a pure iron solution. Compared to HCl and H2SO4 solutions, the use of single ferric solution showed some advantages such as fast reaction kinetics at 22?C and the reduction in the dosage of acids and oxidants.

Таштыкский меч

In 1962, an iron sword entered the funds of the Khakass Museum of Local Lore. It was discovered under random circumstances in the vicinity of the Podsinee village (currently a suburb of the city of Abakan). Yu.S. Khudyakov attributed the sword to the Tashtyk culture and gave a brief description of its size. According to the classifi cation, the sword is in Group I — rhombic, type 1 — with an emphasis for the plate crosshair. An analysis of weapons rare for the Tashtyk culture made it possible to supplement its description and make a number of clarifications. The sword is forged from a strip of iron, including a triangular crosshair. Forge welding was not used, traces of processing with abrasives are not fixed. The blade is straight, at the crosshairs it tapers, the cross section of the blade is rhombic, turning into a lenticular. The handle is rectangular, the end is broken, but presumably it ended with a small hook.With a total length of 53 cm, it is close to the size of «small» swords, and in terms of blade length it meets the standards of akinak. The weight of the sword is 830 grams, the main weight falls on the hilt and crosshairs. This is a weapon of a foot warrior; due to its small size it is not effective for combat use by a mounted warrior. Testing has shown that for thrusting, the index finger is placed over the crosshair, which allows for better control of the blade. In our opinion, the sword is of imported origin.

Decarburisation of Fe-C alloy strips by gas–solid reaction in Ar-CO-CO2

The gas–solid reaction decarburisation of cast iron strips is a direct steel production method with low production costs. In this study, the decarburisation kinetics of Fe-C alloy strips in an Ar-CO-CO2 atmosphere were investigated. Fe-C alloy strips with 4.2 wt.% C and different thicknesses (1, 1.5, and 2 mm) were used for the decarburisation experiments under temperatures of 1293, 1353, and 1413 K. The results indicate that, under appropriate mixed gas conditions, rapid decarburisation can be achieved. With an increase in the decarburisation temperature, the decarburisation rate increases significantly. Under the same decarburisation temperature and time, thinner Fe-C alloy strips exhibit a better decarburisation effect. The decarburisation process includes three rate-limiting stages, namely gas and surface reaction, carbon diffusion, and cementite decomposition. The microstructure of the decarburised strips comprises a complete decarburised layer and a partial decarburised layer, and the thickness of the complete decarburised layer increases with decarburisation time. The decarburisation of the Fe-C alloy strip is an apparent first-order reaction with an activation energy of 124.7 kJ ∙ mol−1, and the activation energy for the growth of the complete decarburised layer is 132.3 kJ ∙ mol−1. The results of this study can help develop more efficient and cost-effective steel production methods.

Removal of Fe(III) from sulfuric acid leaching solution of phosphate ores with bisphosphonic acids

Iron(III) in phosphate ore leach liquor harms the quality of phosphoric acid and phosphogypsum crystallization. In this paper, the selective separation of iron(III) was studied with two novel extractants, N, N-n-octylamine di(methylene phenylphosphonic acid) (OADMPPA) and N, N-n-hexadetamine di(methylene phenylphosphonic acid) (HADMPPA), from a mixed media of sulfuric acid and phosphoric acid. The effects of temperature, time, diluents, and the concentrations of sulfuric acid and extractant on the separation of iron were investigated. The mechanism of extraction was established by UV–Vis spectroscopy, FT-IR spectroscopy, slope analysis, and the equimolar series method. The results showed that the two new reagents have good extraction ability toward iron(III) even at higher sulfuric acid concentration. Both OADMPPA and HADMPPA can remove more than 99% of iron(III) from the sulfuric acid leach liquor of phosphate ore. The stripping of iron(III) from the organic phase after extraction with acidic phosphine (phosphorus) extractants was difficult. Oxalic acid was found to be a good stripping agent. The single stage stripping efficiency reached 62.8%, and the two-stage stripping efficiency could reach over 99%. The separation and recovery of iron(III) in phosphate ore leach liquor could be realized by our method without changing the traditional phosphoric acid production process, which is beneficial to the purification of phosphoric acid and the recovery of iron.

Selective Recovery of Iron by Solvent Extraction from Ni-Laterite Leach Solutions, as Precursor for the Synthesis of High Added-Value Nanomaterials

Iron is the major impurity in the pregnant leaching solutions (PLS) derived from heap and atmospheric acid leaching of low-grade laterite ores. The PLS can be considered as a secondary resource for the synthesis of high added-value iron nanomaterials, provided that the iron is selectively separated from the polymetallic PLS solution. In this study, the feasibility of selective iron separation was investigated by applying a solvent extraction technique based on the use of Di-2-ethylhexyl phosphoric acid (D2EHPA) and Tri-butyl phosphate (TBP) extractants. The effect of several parameters such as initial pH and PLS composition was studied to identify the conditions allowing the maximum possible separation of iron with the minimum co-extraction of other valuable metals. It was found that the best separation of Fe could be obtained when the initial pH of the aqueous phase was regulated close to 1.4. The recovery of iron from the loaded organic phase was studied using sulfuric acid as stripping reagent and elemental iron as solid reducing agent. It was found that 90% of Fe(III) could be stripped out by applying the metallic iron (galvanic) stripping.

Pb-Zn recovery from a malic leach solution of a carbonate type ore flotation tailing by precipitation and solvent extraction

The recovery of zinc and lead from a malic leach solution of a carbonate type ore flotation tailing by precipitation with sulfuric acid followed by solvent extraction using di(2-ethylhexyl)phosphoric acid (D2EHPA) as extractant was investigated. The separation of lead via precipitation was essentially complete from the malic acid leach solution by adding sulphuric acid to reach a pH of 0.25 at 25 °C. The precipitate product was identified by XRD as anglesite (PbSO4). The pregnant leach solution after lead precipitation was then subjected to solvent extraction using D2EHPA. The optimum solvent extraction conditions were determined as 10% D2EHPA concentration, 25 °C temperature, 10 min contact time and phase ratio of unity. Under these conditions, 99.3% of zinc was extracted into the organic phase at a pH of 4.2 in a single contact alongside a substantial amount of Ca (76.6%), and minor amounts of Fe (19.2%) and Mg (18%). Complete stripping of zinc and calcium from the loaded organic solution along with 47.8% of Mg was achieved at a pH 0.5 under room temperature. No iron stripping was observed from the loaded organic. The zinc content in the loaded strip solution could be enriched and then sent to the electrowinning (EW) stage. It is noted that the calcium and magnesium impurities in the loaded strip solution had no adverse effect on the zinc EW process. Based on the experimental results, a flowsheet was proposed for the recovery of Pb and Zn from the malic acid leach solution. With the proposed precipitation and solvent extraction process, two different material streams are produced.

Solvent Extraction of Iron(III) from Al Chloride Solution of Bauxite HCl Leaching by Mixture of Aliphatic Alcohol and Ketone

Research into the solvent extraction of iron(III) from a chloride solution after bauxite HCl leaching by neutral oxygen-containing extractants and their mixtures were studied and the iron(III) extraction degree from chloride solutions using alcohols is presented. The effect of dilution of alcohol with a ketone by an extraction mixture in relation to its effectiveness was investigated. The iron(III) was efficiently extracted by the mixture of 1-octanol and 1-decanol (70%) with 2-undecanone (30%) from hydrochloric bauxite leach liquor at an O:A ratio = 2-4:1 at an iron(III) concentration of 7.4 g/L and 6 M HCl. For the removal of iron-containing organic phase from impurities (Al, Ca, Cr) that are co-extracted with iron(III), we used two step scrubbing at O:A = 5:1 by 7 M HCl as a scrub solution. The iron(III) stripping at the O:A ratio is shown. Using counter-current cascade of extractors, it was possible to obtain an FeCl3 solution with the iron(III) content of 90.5 g/L and total impurities less than 50 mg/L.

Selective removal of iron(III) from highly salted chloride acidic solutions by solvent extraction using di(2-ethylhexyl) phosphate

Metal ions including Fe3+, Ca2+, Mg2+, Ni2+, Co2+ and Cu2+ are commonly found in the leaching solution of laterite-nickel ores, and the pre-removal of Fe3+ is extremely important for the recovery of nickel and cobalt. Di(2-ethylhexyl)phosphate acid (D2EHPA) showed high extraction rate and selectivity of Fe3+ over other metal ions. The acidity of the aqueous solution is crucial to the extraction of Fe3+, and the stoichiometry ratio between Fe3+ and the extractant is 0.86:1.54. The enthalpy for the extraction of Fe3+ using D2EHPA was 19.50 kJ/mol. The extraction of Fe3+ was ⩾ 99% under the optimized conditions after a three-stage solvent extraction process. The iron stripping effects of different reagents showed an order of H2C2O4 > NH4HCO3 > HCl > NaCl > NaHCO3 > Na2SO3. The stripping of Fe was ⩾ 99% under the optimized conditions using H2C2O4 as a stripping reagent.

Typology of the medieval axes from the north of Western Siberia

The paper presents the results of the research on the Middle Ages iron axes found in different years in the north of Western Siberia and the Urals, excluding pole-axe (berdysh Rus.) that appear in large numbers in the study area with the growing of the Russian population. The relevance of such study has matured, since there are enough sources that need to be generalized and critically compiled. Taking into account the morphological features of the archaeological evidence, the authors propose to classify all currently known axes by 2 groups and 13 types. The first group including 3 types of minting axes were made exclusively for combat use. The second group includes 10 types of axes, classified as universal, which served both for the military and for economic purposes. The text with the description of the sites contains also table with the data on the basic parameters of axes (item length, blade width) and the time of their use (existence). For the first time, a new type of battle axe (type 13), accidentally found in the Khanty-Mansi Autonomous Okrug — Ugra, is published. We present analogues of this subject among the products of Russian blacksmiths of the 13th–14th centuries and explain the position on the dating and on origin of the axe. The paper discusses the evolution of certain types of objects, describes plots concerning the origin of certain items (imports from Volga Bulgaria, Russian lands, etc.) and the special attitude of the local population to this type of weapon, which could be stored for centuries in the holy places of the Ob Ugrians. The authors come to the conclusion that imported axes of the second group were used as a standard for Siberian blacksmiths. But local products, characterized by primitive technology (a multilayer package), low quality welding of iron strips and an abundance of slag inclusions, can be finally identified only after metallographic microstructural analysis. This research should be prolonged, because annual archaeological investigations replenish the source base, and, with no doubt, the typology of axes proposed in the article will be supplemented and adjusted.

An electrochemical analysis of acute contamination of environmental water and restoring of water quality using taro carbon

Electrochemical techniques were successfully employed to estimate contamination of water of river Buriganga, Bangladesh. A Pt–Cu electrode has been exploited to measure selective nitrate concentration, and corrosion rate of iron has been proposed to indicate relative abundance of dissolved contaminants. In order to evaluate the pollution level, water parameters of river Buriganga have been compared with those obtained from two freshwater streams named Surma and Dawki of the country. An iron strip in contact with Buriganga river water is corroded three times rapidly compared to its contact with Dawki or Surma river water indicates acute contamination of Buriganga river water. The River Buriganga is facing acute pollution from the point of high TDS (0.664–0.694 g/L), low DO (1.47–4.4 mg/L), high COD (197–218 mg/L), high ammonia (270–420 mg/L) and high nitrate concentration (107–157 mg/L). Negative ORP value (− 292 to − 310 mV) of Buriganga river water indicates that the stream contains high level reducing species. Meanwhile, positive ORP value indicates that Dawki (+ 203 to + 209 mV) and Surma (+ 184 to + 205 mV) river water contain oxidizing species. Sediment analysis shows the deposition of disintegrated organic pollutants on the bottom of the River Buriganga. Cost-effective carbon material synthesized from taro stems has been proposed to restore water parameters of filthy water system like Buriganga river.

Separation and recovery of vanadium and iron from oxalic-acid-based shale leachate by coextraction and stepwise stripping

Iron is the main element that affects the purification and enrichment of vanadium solutions. In traditional solvent extraction, only the vanadium is recovered and the iron is lost. Thus, the separation and recovery of vanadium and iron from an oxalic-acid-based shale leachate by coextraction and stepwise stripping was investigated. The results showed that vanadium and iron were selectively separated and recovered by coextraction and stepwise stripping. In the coextraction, 98.60% and 99.64% of the vanadium and iron, respectively, were coextracted after six-stage countercurrent extraction using Aliquat 336. The coextraction mechanism was determined to be an anion exchange reaction between the anionic complexes of vanadium and iron and Aliquat 336. In the selective stripping of vanadium, 99.35% of the vanadium and only 0.32% of the iron were stripped after four-stage countercurrent stripping using HCl, and the vanadium-to-iron separation factor was as high as 47956. The selective stripping mechanism was that the anionic complexes of iron and oxalate were transformed into [FeCl4]– in HCl solution, and the [FeCl4]– was extracted again by Aliquat 336. In the stripping of iron, 99.62% of the iron was stripped by NaOH, forming a Fe(OH)3 precipitate with a purity of 98.5%. Compared to direct chemical precipitation and traditional solvent extraction, this process has fewer steps and is more efficient. Furthermore, vanadium and iron can be separated and recovered simultaneously, and the comprehensive utilization of resources is improved.

Concentration and Separation of Heavy Rare-Earth Metals at Stripping Stage

The separation and concentration processes of heavy rare-earth metals—yttrium, ytterbium, erbium, and dysprosium—during stripping from the organic phase based on di-2-ethylhexylphosphoric acid (D2EHPA, or DEHPA) solutions were investigated in this work. Optimal conditions providing high separation factors of rare-earth metals (REM) and their extraction degree to the aqueous phase were determined. The usage of sulfuric acid solutions with a concentration of 2–6 mol/L, depending on the type of extracted rare-earth element, was proposed as a stripping agent for rare-earth metals (REM), and the usage of oxalic acid solution was proposed as an iron stripping solution from the organic phase. To increase the REM stripping efficiency, the antagonistic effect of tributyl phosphate in the di-2-ethylhexylphosphoric acid-kerosene-tributyl phosphate system was considered. The possibility of increasing the capacity of the organic solvent by cleaning the organic phase from iron ions using oxalic acid solutions was revealed. The influence of temperature, aqueous and organic phase ratio, stirring rate, and re-extractant concentration on the distribution and separation factors of adjacent heavy rare-earth-metal (HREM) pairs during the re-extraction process were determined. A schematic diagram of the laboratory-tested separation process of heavy rare-earth metals into individual components with the obtaining of yttrium and ytterbium concentrates containing more than 99% of the target components was proposed.

Copper and Iron Extraction from Nickel Sulfate Electrolytes Using Binary Extractants

The extraction of copper(II) and iron(III) from nickel sulfate electrolytes by means of solutions of binary extractants such as methyltrioctylammonium, tetraoctylammonium and trioctylammonium caprylates, 2-ethylheptylcarboxylates, and di(2-ethylhexyl)phosphates in toluene has been studied. It has been shown that an efficient copper extraction is observed in the systems with methyltrioctyl ammonium dialkyl carboxylate and caprylate, whereas methyltrioocylammonium, and tetraoctylammonium salts can be used to extract iron. The stripping of copper and iron can be carried out using dilute sulfuric acid solutions.

Stripping of iron(III) from iron(III)-loaded Aliquat 336 generated during aluminum recovery from coal waste leach liquor using sodium sulfite

Abstract Stripping is a necessary step for the recovery and reuse of extracting agent in hydro metallurgical process. This study reported an effective way employing sodium sulfite for the stripping of iron(III) from Aliquat 336 with a high iron loading, which was generated in the iron removal from coal waste hydrochloric acid leach liquor. The stripping behavior has been studied using iron(III)-loaded Aliquat 336 obtained after the extraction of iron(III) from synthetic ferric chloride solution. The results showed that approximate 95% of iron(III) can be stripped from Aliquat 336 loaded with up to 70 g/L of iron(III) after only one time of contact under the optimum conditions, where 0.8 mol/L of sodium sulfite was used to strip(III) iron from Aliquat 336 for 30 min at 50 °C with a 1:2 vol phase ratio (O/A, volume of iron(III)-loaded Aliquat 336–0.8 mol/L sodium sulfite aqueous solution). The stripping mechanism of iron(III) with sodium sulfite can be explained as the combination reactions of hydrolysis and reduction. Increasing the stripping temperature favored the stripping of iron(III). The stripping method was further tested to remove iron from Aliquat 336 after being used for the extraction of iron(III) from coal gangue hydrochloric leach liquor. The results showed more than 95% of iron(III) can be extracted after Aliquat 336 being recycled for nine times using 0.8 mol/L sodium sulfite as stripping solution, which is far more effective than sulfuric acid or deionized water employed in the previous reports, further simplifying the stripping operation and reducing the extractant loss.

Hydrogen Diffusion Transport in an All-Iron Flow Battery Rebalance System

All-iron flow batteries (IFBs) are being developed for low-cost large-scale energy storage applications. IFBs use abundantly available, non-toxic and low cost electrolyte materials[1]. The all-iron flow battery involves plating and stripping of metallic iron in the negative half-cell and utilizes the Fe II/III (ferrous/ferric) redox couple reaction at its positive electrode[2-3]. Hydrogen evolution occurs as the iron deposits at the negative electrode during the flow battery charging and even if the amount might be small, there will be an impact on the electrolyte balance over many cycles. Recently, Selverston et al.[3] demonstrated a concept of hydrogen rebalance in an all-iron flow battery through designing a capillary-action galvanic reactor (CGR) to consume hydrogen and reduce excess ferric ions in the positive electrolyte reservoir. This design can maintain the balance of protons and reduce undesired precipitation reactions. A tube connects the negative tank headspace where hydrogen collects to the positive tank headspace where the CGR reactor is placed. An understanding of design factors on hydrogen transport through the tube between headspaces is desired and mathematical modeling[4-7] is the approach we took to achieve this. In this poster, we report a mathematical model of hydrogen diffusion between the headspaces of the negative electrolyte tank and the positive electrolyte tank. The effects of dimensional parameters, including diameter of tank, height of tank, diameter of tube, length of tube and diffusion coefficient on hydrogen diffusion rates and partial pressure are investigated during both battery charge and battery standby cases. In Figure 1, we demonstrate that the mathematical model is reasonably validated by the previous published experimental data for a specific all-iron flow battery rebalance device. Acknowledgements This work is supported by the all-iron flow battery project (grant number: DE-AR0000352) funded by Department of Energy (DOE) of the United States.