Selective Removal Of Iron Research Articles

Selective removal of iron from sulfuric acid leaching solution of aerospace magnetic material scraps by jarosite process

Aerospace magnetic material scraps are abundant in cobalt and nickel. Sulfuric acid leaching process is an efficient method for extracting them. But it is a non-selective process, a significant amount of iron dissolves in the solution. This study focuses on the selective removal of iron from this solution using the jarosite process. Eh-pH diagram of K-S-Fe-H2O system was established. Based on thermodynamic analysis, H2O2 is used to oxidize Fe2+ into Fe3+, achieving efficient and selective removal of iron from the solution containing cobalt and nickel. The optimal conditions are as follows: temperature 95°C, K2SO4 dosage coefficient 1.5, seed dosage 10 g/L, time 90 min, pH 1.76, and endpoint pH controlled at approximately 3. Under these conditions, the iron removal efficiency is above 99%, while the loss ratios of cobalt and nickel are below 2%. The product is characterized by XRD and SEM-EDS. Results indicate that the product is jarosite ((K,H3O)Fe3(SO4)2(OH)6), exhibiting an ellipsoid structure with the mean particle size in the range of 0.2–5.0 μm. Temperature, pH value and seed dosage significantly affect reaction rate, particle size and crystallinity, and K2SO4 dosage mainly affects reaction rate and the morphology of jarosite. The jarosite crystallization kinetics can be described by the Avrami equation, with an Avrami index (n) of approximately 2.5 and the apparent activation energy of 42.68 kJ/mol.

Selective recovery of rare earth elements by smelting of magnets

Rare earth elements (REEs) play a crucial role in many technologies from daily appliances in cell phones to more advanced wind turbines and electric cars. Permanent magnets account for a quarter of total global REEs production and have high recycling value. In this study, smelting process was used to selectively oxidize REEs in the permanent magnets by adding Fe2O3. This separates REEs into a slag phase from an iron-rich metallic phase. B2O3 was also added to the system as a flux to lower the slag melting temperature. This minimizes REEs loss to the metallic phase and allows a more efficient phase separation. The effect of flux and oxidizing agent addition was investigated on both regular and cerium-rich NdFeB (NdCeFeB) magnets. At 1350 °C and for 1 h, the slag phase was successfully separated from the metallic phase with the addition of 0.8 stoichiometric amount of Fe2O3 and 40 wt% of B2O3. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDX) analysis reveals that REEs in the magnet do not migrate to the metal phase while the REE-rich slag phase contains almost no iron. After the selective removal of iron into the metallic phase, REEs are recovered from the slag phase through an acid leaching process allowing >99% of REEs recovery. Boron in the magnet can also be recovered as useful boric acid by evaporation and crystallisation technique. The proposed process in this study is reagent and energy-efficient with almost complete valorisation of both NdCeFeB and NdFeB magnets.

Selective Removal of Iron, Lead, and Copper Metal Ions from Industrial Wastewater by a Novel Cross-Linked Carbazole-Piperazine Copolymer.

A novel cross-linked Copolymer (MXM) was synthesized by the polycondensation reaction of 3,6-Diaminocarbazole and piperazine with p-formaldehyde as a cross-linker. The Copolymer was fully characterized by solid 13C-NMR and FT-IR. The thermal stability of MXM was investigated by TGA and showed that the Copolymer was stable up to 300 °C. The synthesized polyamine was tested for the removal of iron (Fe2+), lead (Pb2+), and copper (Cu2+) ions from aqueous and industrial wastewater solutions. The effect of pH, concentration and time on the adsorption of iron (Fe2+), lead (Pb2+), and copper (Cu2+) ions was investigated. The adsorption of the studied ions from aqueous solutions onto the MXM polymer occurs following the Freundlich isotherm and pseudo-second-order kinetic models. The intraparticle diffusion model showed that the adsorption mechanism is controlled by film diffusion. The regeneration of MXM showed practical reusability with a loss in capacity of 2–5% in the case of Fe2+ and Cu2+ ions. The molecular simulation investigations revealed similarities between experimental and theoretical calculations. Industrial wastewater treatment revealed the excellent capabilities and design of MXM to be a potential adsorbent for the removal of heavy metal ions.

Shifting the distribution: modulation of the lipid profile in Yarrowia lipolytica via iron content.

Microbial fermentation offers a sustainable source of fuels, commodity chemicals, and pharmaceuticals, yet strain performance is influenced greatly by the growth media selected. Specifically, trace metals (e.g., iron, copper, manganese, zinc, and others) are critical for proper growth and enzymatic function within microorganisms yet are non-standardized across media formulation. In this work, the effect of trace metal supplementation on the lipid production profile of Yarrowia lipolytica was explored using tube scale fermentation followed by biomass and lipid characterization. Addition of iron (II) to the chemically defined Yeast Synthetic Complete (YSC) medium increased final optical density nearly twofold and lipid production threefold, while addition of copper (II) had no impact. Additionally, dose-responsive changes in lipid distribution were observed, with the percent of oleic acid increasing and stearic acid decreasing as initial iron concentration increased. These changes were reversible with subsequent iron-selective chelation. Use of rich Yeast Peptone Dextrose (YPD) medium enabled further increases in the production of two specialty oleochemicals ultimately reaching 63 and 47% of the lipid pool as α-linolenic acid and cyclopropane fatty acid, respectively, compared to YSC medium. Selective removal of iron (II) natively present in YPD medium decreased this oleochemical production, ultimately aligning the lipid profile with that of non-supplemented YSC medium. These results provide further insight into the proposed mechanisms for iron regulation in yeasts especially as these productions strains contain a mutant allele of the iron regulator, mga2. The work presented here also suggests a non-genetic method for control of the lipid profile in Y. lipolytica for use in diverse applications. KEY POINTS: • Iron supplementation increases cell density and lipid titer in Yarrowia lipolytica. • Iron addition reversibly alters lipid portfolio increasing linolenic acid. • Removal of iron from YPD media provides a link to enhanced oleochemical production.

Selective removal of iron(III), lead(II) and copper(II) ions by polar crude phytochemicals recovered from ten South African plants: identification of plant phytochemicals

This work consists of gathering the leaves of ten different South African plants from the local reserve. Black and green tea were sourced commercially. The plants were air dried and polar crude material extracted using deionized water. These crude phytochemicals were used as green chelators to remove metal ions from an aqueous solution. Iron(III), lead(II) and copper(II) ions were competitively removed from an eight metal ion solution with iron(III) being removed at more than 80% followed by lead(II) with greater than 40% removal and copper(II) with removal values of more than 20%. Metal ion removal was shown to be affected by change in pH of the solution, indicating that removal took place via the pH-swing mechanism. As the pH is increased, iron(III) is first removed followed by lead(II) and then copper(II). Iron(III) and lead(II) were selectively removed even at a 10-fold dilution level compared to the other metal ions present. Loading tests showed that iron(III) removal does not change, but for lead(II) and copper(II) there is a noticeable increase in removal with an increase in the amount of crude. The phytochemicals in the crude were identified using Liquid chromatography-tandem mass spectrometry (LC-MS/MS). Some crudes had similar phytochemicals (quercetin) while others had unique compounds. Statement of novelty It is the first time that crude polar phytochemicals from South African plants are used as green chelators. These green chelators selectively remove iron(III), lead(II) and copper(II) from a mix of eight different base metal ions. Iron(III) can be selectively removed at pH as low as 3.00 and, when iron(III) and lead(II) are 10 times more dilute compared to the other metal ions, iron(III) and lead(II) are still selectively removed. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is used to identify some of the phytochemicals present in these plants.

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.

Selective Removal of Iron from Acid Leachate of Red Mud by Aliquat 336

Extraction of valuable rare-earth elements (REEs) from red mud is important for both resource recovery and waste treatment of red mud. However, the Fe present in red mud makes the extraction of REEs unsatisfactory, because Fe(III) is co-extracted and is difficult to remove. In this study, the feasibility and mechanism of selective removal of Fe from the acid leachate of red mud using Aliquat 336 were investigated. According to the theoretical calculation, Fe(III) mainly existed as FeCl3 species in a wide range of chloride concentrations, and the concentration of FeCl4− species significantly increased with chloride concentration. The extraction studies show that the chloride concentration strongly affects the extraction of Fe. The Fe removal efficiency is > 98% when the chloride concentration is 2.65 mol L−1, while the loss of REEs is 90% under the optimal conditions.

Production of High-Grade Titanium Dioxide Directly from Titanium Ore Using Titanium Scrap and Iron Chloride Waste

In order to produce high-grade titanium dioxide (95% TiO2) directly from a titanium ore using titanium scrap and iron chloride waste, chlorine recovery and selective chlorination processes were investigated. The mixture of titanium scrap and ferrous chloride in carbon crucible and titanium ore in quartz crucible were placed inside gas-tight quartz tube. The experiments were conducted at 1193–1248 K. Titanium tetrachloride and metallic iron were produced by the chlorination of titanium scrap in the carbon crucible, and the chlorination ratio of titanium chip was 94.6%. In the quartz crucible, 96.2% TiO2 was obtained under certain conditions by the selective removal of iron from the ore because of the reaction with the generated TiCl4. The iron removal ratio of titanium ore was 98.2%. Therefore, the feasibility of the effective use of titanium scrap and iron chloride waste for upgrading titanium ore was demonstrated in this study.

Selective nickel recovery from iron-rich solutions

ABSTRACTThis study aims to demonstrate the selective removal of iron from acidic leach solutions using an effective purification method and to convert nickel into a usable form. The method of removing iron by using CaCO3, which is a better precipitation reagent, was optimized using Response Surface Methodology. A further evaluation was carried out on the complexation of Ni(II) ions with dimethylglyoxime to obtain a high-yield nickel-dimethylglyoxime complex from nickel remaining in the solution after iron precipitation. Taking into account nickel losses to remove iron, pH should be within the range of 3–4, and low temperatures around 25°C should be used.

Selective Removal of Iron from Low-Grade Ti Ore by Reacting with Calcium Chloride

Recently, titanium metal production by molten salt electrolysis using CaCl2 as molten salt and TiO2 or rutile (94 to 96 pct TiO2) as feedstock has been drawing attention. However, when a low-grade Ti ore (mainly FeTiO3) is used as feedstock, removal of iron (Fe) from the ore is indispensable. In this study, the influence of reaction temperature, reaction time, particle size of the ore, and source country for the ore on the removal of iron by selective chlorination using CaCl2 was assessed. Experimental results showed that the mass percent of iron in the ore decreased from 49.7 to 1.79 pct under certain conditions by selective removal of iron as FeCl2. As a result, high-grade CaTiO3 was produced when the ore particles smaller than 74 µm reacted with CaCl2 at 1240 K (967 °C) for 8 to 10 hours. Therefore, this study demonstrates that the removal of iron from the ore is feasible through the selective chlorination process using CaCl2 by optimizing the variables.

Selective removal of iron(III) from synthetic copper(II) pregnant leach solutions using [bmim][Tf2N] as diluent and TFA as extracting agent

High concentrations of iron represent a drawback in the hydrometallurgy of copper, since this metal cation could be co-extracted or entrained to the electrowinning step causing difficulties in obtaining pure copper. In this work, a pre-treatment step based on solvent extraction of iron using a hydrophobic imidazolium-based ionic liquid is proposed to overcome this drawback. The ionic liquid [bmim][Tf2N] was used as the diluent. The β-diketone TFA was used as the extractant. The results show that the combination extractant-ionic liquid is capable to remove iron(III) selectively from a pregnant leach solution (PLS) containing mainly copper(II) and iron(III) at low pH values. Furthermore, the use of this ionic liquid as diluent shows high extraction capacities. Finally, 97% of iron(III) can be stripped from the ionic liquid using a diluted solution of sulfuric acid (2M).

Studies of Selective Removal of Iron (III) from the Simulated Bauxite Hydrochloric Acid Leaching Liquor by Solvent Extraction

Solvent extraction technique was performed to optimize the conditions for maximum removal of iron (III) from the simulated bauxite hydrochloric acid leaching liquor of FeCl3+AlCl3+CaCl2+HCl. Some factors influencing the extraction, such as the extractant and concentration of Fe, Al, and Ca were investigated. The results indicated that the N235 is an effective extractant for selective extraction of iron (III) from chloride liquor. The concentration of Fe in raffinate is under 0.0165 gL-1 and the losing of Al is 0.50 % by N235.

Selective Removal of Iron from Aqueous Solution using Ion Imprinted Cyanato-Functionalized Silica Gel Sorbents

We combined a surface imprinting technique with sol-gel process for preparing a new iron(III)-imprinted cyanato-functionalized silica gel sorbents using (3-cyanatopropyl)triethoxysilane as the functional monomer, and epichlorohydrin as the cross-linking agent for the selective removal of iron(III) from aqueous solution. The iron(III)-imprinted cyanato-functionalized silica gel was characterized by FT-IR spectra and the static adsorption-desorption method. Maximum binding capacity, optimum pH, and equilibrium binding time were found to be 35.6 mg · g−1, pH 3, and 20 min, respectively. The relative selectivity coefficients of ion imprinted cyanato-functionalized silica gel sorbents for Fe(III)/Ni(II), Fe(III)/Co(II), Fe(III)/Cd(II), and Fe(III)/Pb(II) were 8.56, 11.95, 16.96, and 50.71 times greater than the non-imprinted silica gel, respectively. The iron(III)-imprinted cyanato-functionalized silica gel sorbents could be used repeatedly without significantly decreasing their adsorption capacities.

Selective Removal of Iron from Chromite Ore Overburden

A process to upgrade the nickel-rich fraction of the chromite ore overburden, mined from the Sukinda belt of Orissa state on the eastern coast of India, has been developed. The composition of this fraction is similar to that of the lateritic nickel ore deposits of this region. It was possible to upgrade the nickel content from an initial value of ∼ 1 wt.% to a final value of 3 wt.% NiO by selectively removing iron from the overburden, through a combination of sulphurization and chlorination processes. The optimum parameters to ensure maximum removal of iron have been established.

Free radical generation in the toxicity of inhaled mineral particles: the role of iron speciation at the surface of asbestos and silica

Free radical generation at the particle/biological fluid interface is one of the chemical processes that contributes to pathogenicity. In order to investigate the role played by iron, fibres of crocidolite asbestos have been modified by thermal treatments to alter their surface iron content. Two radical mechanisms, HO• from H2O2 and cleavage of a C–H bond, which are both active on the original fibres, have been tested on the modified fibres. C–H cleavage is dependent on Fe(II) abundance and location and is suppressed by surface oxidation while HO• release appears independent of the oxidation state of iron. Quartz specimens with different levels of iron impurities have been tested in a similar manner. A commercially available quartz (Min-U-Sil 5) containing trace levels of iron is also active in both tests, but reactivity is not fully suppressed by treatment with desferrioxamine, which should remove/inactivate iron. The radical yield attained is close to the level produced by a pure quartz dust, suggesting the presence of active sites other than iron. Ascorbic acid reacts with both crocidolite and quartz, with subsequent depletion of the level of antioxidant defences when particle deposition occurs in the lung lining layer. Following treatment with ascorbic acid the radical yield increases with quartz, but decreases with asbestos. Selective removal of iron and silicon from the surface may account for the differences in behaviour of the two particulates.

Selective removal of iron from grape juice using an iron(III) chelating resin

Abstract This work reports the results of iron removal from grape juice with an iron(III) chelating resin in both batch separation and column separation processes. The separation experiments indicated that the iron(III) chelating resin removed iron selectively and effectively from grape juice. The iron content in grape juice was reduced from 1000 ppb to 2 ppb with a batch separation at a ratio of 1 g of the resin to 100 ml of grape juice. By using a sequential multi-batch separation process or a column separation process, the iron level in grape juice could be reduced to 1 ppb with the iron(III) chelating resin. It was found that selective removal of iron was completed within 3 h. The chelating resin did not remove other metals such as Co, Mg, Ca, Zn, Mn, K and Na in the grape juice. Mo and Cu, however, were partially removed. Preliminary microbial tests indicated that the growth of the wine yeast ( Saccharomyces cerevisiae ) was partially inhibited in the iron-deficient grape juice.

Selenium determination by HG-ICPAES: Elimination of iron interferences by means of an ion-exchange resin in a continuous flow system

An accurate procedure for the elimination of iron interferences in the determination of selenium in geological materials by the Hydride Generation – Inductively Coupled Plasma Atomic Emission Spectrometry technique (HG-ICPAES) is proposed. A selective removal of iron is achieved by on-line incorporation of a microcolumn filled with strongly acidic cation exchange resin (Dowex 50W-X8). The microcolumn manifold used was interfaced with the hydride generation manifold by a flow injection sample injection valve. After the removal of the iron, a 500 μl sample was injected into a carrier stream of water. This was merged with hydrochloric acid and sodium tetrahydroborate in order to generate the corresponding selenium hydride. The system was found to have a limit of detection of 0.4 ng ml-1 and a relative standard deviation of 2% for 20 ng ml-1 selenium. The application of the method on different Geochemical Standard Reference Samples demonstrated that results were statistically indistinguishable from certified values.

Studies of the relative importance of iron and aluminium in the sorption of phosphate by some Australian soils

Phosphate sorption by 47 acid surface soils was correlated with the amounts of iron and aluminium extracted from them by ammonium oxalate at pH 3.2. The correlation coefficients, when all soils were considered, were highest for sorption and aluminium. For certain groups of soils, iron or iron plus aluminium gave higher coefficients than did aluminium. The relative contributions of iron and aluminium to phosphate sorption could not be accurately assessed from these correlation coefficients because iron and aluminium themselves were positively correlated. Eleven of the forty-seven soils were chosen for determinations of the effect of selective removal of iron and aluminium on their ability to sorb phosphate. Soils usually sorbed less phosphate after various amounts of their iron and aluminium had been extracted chemically. Many of them, however, still sorbed large amounts of phosphate in spite of the removal of reducible iron and acid-soluble aluminium. Soils and haematite extracted with sodium dithionite in acetate at pH 5.0 usually sorbed more phosphate than untreated samples. This was due largely to the incomplete removal of reduced iron and could be prevented by washing with dilute acid. Acid washing after dithionite treatment caused sorption by the soils to fall below the values for the untreated samples and virtually destroyed that of the oxide. It also removed much aluminium from the soils. The amount by which sorption fell below that of the untreated samples could be accounted for largely by this aluminium. It was concluded tentatively that, for most of the soils, phosphate sorption was due to acid-soluble aluminium and to sorption sites which were non-reducible and insoluble in dilute acid. The contribution of reducible iron in the original soils remains in doubt, but it could be a minor one.

Corrosion and Metal Transport In Fused Sodium Hydroxide (Part 2 – Corrosion of Nickel-Molybdenum-Iron Alloys)

Abstract Studies were made of the corrosion by fused sodium hydroxide of nickel-rich alloys whose constituents were nickel, molybdenum, and iron exposed at 815 C for 100 hours. The reaction mechanism was found to involve the selective removal of iron and molybdenum from solid solution with nickel and a resultant formation of subsurface porosity. In most cases this porosity was shown to occur in the form of elongated pits which frequently followed tortuous paths and intersected to form a maze of subsurface channels. Alloys of nickel, molybdenum, and iron containing at least 70 percent nickel showed more resistance to corrosion by sodium hydroxide melts at 815 C than any other alloys which have been tested. 4.7