Fe Source Research Articles

High-efficient nitrogen removal with low demand of Fe source and mechanism analysis driven by Fe(II)/Fe(III) cycle

Feammox (Fe(III) reduction coupled with anaerobic ammonium oxidation) is less studied for nitrogen removal in wastewater treatment, and the limited studies show its low removal efficiency and need for continuous resupply of Fe(III) sources. In this study, sustainable and efficient nitrogen removal was obtained by the Fe redox cycle with only 1 g/L Fe2O3 dosage. The removal efficiencies of NH4+-N and TN were 100% and 92.45%, respectively, significantly higher than previous studies (∼50%). Fe(III) was reduced to Fe(II) by Feammox and subsequently regenerated by NDFO (NOx--N-dependent Fe(II) oxidation) and chemical oxidization. NOx--N produced by Feammox was also reduced to N2 by NDFO. The iron-reducing bacteria (Ferruginibacter and Dechloromonas) and the iron-oxidizing bacteria (Rhodanobacter and Thermomonas) were enriched by the addition of Fe2O3 and played important roles in Feammox and NDFO, respectively. Results of X-ray diffraction showed that Fe(OH)2 was produced from Feammox and then transformed to lepidocrocite by Fe(II) oxidation. Metagenomic analysis showed D/ANRA (dissimilatory/ assimilatory nitrate reduction to ammonia) were the potential nitrogen conversion pathways. N2O as an intermediate product of Feammox or NDFO was undetected. The genes associated with Fe transport were upregulated, accelerating the transfer of electrons between microorganisms and Fe(Hydr)oxide. The process for nitrogen removal by the Fe redox cycle requires no aeration and no organic carbon source, and can reduce the need for Fe(III) sources. It offers a promising method for nitrogen removal from wastewater.

Chelated- and nano iron fertilization affects nutrient uptake and translocation in fresh market tomatoes

Our study aimed to evaluate the effects of nano and chelated Fe fertilization on nutrient and heavy metals uptake and their translocation from soil to root, stem, leaf, and fruits of fresh market tomatoes (Solanum Lycopersicon, cv. Sunbrite). A completely randomized design in a factorial experiment, with two Fe sources (nano vs. chelated) applied at 0 (control), 10, 20, and 40 mg/L via drip-irrigated plasticulture, was conducted. Nutrient and heavy metals concentrations in soil, water, tomato roots, stems, leaves, and fruits were determined. Soil had higher K, Fe, Ca, Mg, P, and Mn but lower Ni, Cd, and Cr concentrations. The P, K, Fe, Cu, Mn, and Na concentrations in the roots were significantly affected by both nano and chelated Fe fertilization; however, without following a consistent pattern. Averaged across the Fe treatments, K, Ca, Mg, Fe, and P that translocated from the soil were dominated in the roots, stems, and leaves. The nutrient translocation order, from roots to fruits in response to Fe fertilization, was nano Fe (40%) > chelated Fe (37%) > control (23%). Based on the treatment index values calculated across treatments, it is evident that Fe fertilization plays a pivotal role in nutrient uptake and translocation. The use of chelated Fe at a concentration of 20 mg/L had a pronounced effect on improving the nutritional quality of the tomatoes and, by extension, their associated public health benefits. In conclusion, the chelated Fe (20 mg/L) stands out as the most preferable and effective Fe fertilization for tomatoes.

Synthesis of NiFe-layered double hydroxides using triethanolamine-complexed precursors as oxygen evolution reaction catalysts: effects of Fe valence.

The synthesis of highly efficient NiFe-layered double hydroxides (NiFe-LDHs) to catalyze the oxygen evolution reaction (OER) is urgent and challenging. Herein, NiFe-FeCl3-x and NiFe-FeCl2-x samples (where FeCl3 and FeCl2 represent the Fe sources and x represents the imposed reaction time: 6, 12, and 24 h) were prepared via one-pot hydrothermal synthesis using Fe sources characterized by Fe(III) or Fe(II) valence states. In the presence of triethanolamine, when FeCl3 was used as the Fe source, pure NiFe-LDH was obtained, whose crystallinity increased with increasing hydrothermal treatment time. In contrast, when FeCl2 was used as the Fe source, a mixture of NiFe-LDH, Fe2O3, and trace amounts of Fe3O4 was obtained. The content of NiFe-LDH in the mixture increased under longer hydrothermal treatment and NiFe-FeCl3-x catalysts exhibited better OER performance than NiFe-FeCl2-x catalysts. Specifically, NiFe-FeCl3-6 afforded the highest OER performance with an overpotential of 246.8 mV at 10 mA cm-2 and a Tafel slope of 46.1 mV dec-1. Herein, we investigated the effects of the valence state of Fe precursors on the structures and OER activities of the prepared catalysts; the mechanism of NiFe-LDH formation via hydrothermal synthesis in the presence of triethanolamine was also proposed.

One-step hydrothermal synthesis of a Ni3S2-FeMoO4 nanowire-nanosheet heterostructure array for synergistically boosted oxygen evolution reaction.

A key factor for boosting oxygen evolution reaction (OER) is the design of heterostructures with steerable defects and interfaces, which can optimize the surface electronic structures and achieve efficient water splitting to produce hydrogen fuel. Herein, we propose a novel one-step hydrothermal approach to fabricate hierarchical Ni3S2 nanowires with an S-doped FeMoO4 nanosheet heterostructure array in situ on Ni-Fe foam (NFF) as a self-standing electrode for synergistically boosted OER. The metalloid Ni3S2 nanowires with good conductivity support the FeMoO4 nanosheets and act as high-speed paths for the charge transfer. Numerous ultrathin S-doped FeMoO4 nanosheets are uniformly distributed on each Ni3S2 nanowire to form heterostructures with larger specific surface area and more revealable active sites, and a strong synergistic effect is created at the heterostructure interfaces to further promote the OER dynamics. Additionally, the NFF serves as the conductive support substrate and simultaneously provides the Ni and Fe sources for the self-growing Ni3S2-FeMoO4, leading to a structurally-integrated electrode with low contact resistance, fast mass transfer, and good stability. Therefore, the Ni3S2-FeMoO4/NFF electrode offers a low overpotential of 331 mV to achieve 500 mA cm-2 and long-term stability at 100 mA cm-2 level for more than 40 h. This work provides insight into the heterostructure of molybdate and sulfide, and a deep understanding of the significance of the synergism in OER operation.

Quantifying anthropogenic emission of iron in marine aerosol in the Northwest Pacific with shipborne online measurements

Anthropogenic emissions are recognized as significant contributors to atmospheric soluble iron (Fe) in recent years, which may affect marine primary productivity, especially in Fe-limited areas. However, the contribution of different emission sources to Fe in marine aerosol has been primarily estimated by modeling approaches. Quantifying anthropogenic Fe based on field measurements remains a great challenge. In this study, online multi-element measurements and Positive Matrix Factorization (PMF) were combined for the first time to quantify sources of atmospheric Fe and soluble Fe in the Northwest Pacific during a cruise in spring 2015. Fe concentration in 624 atmospheric PM2.5 samples measured online was 74.58 ± 90.87 ng/m3. The PMF results showed anthropogenic activities, including industrial coal combustion, biomass burning, and maritime transport, were important in this region, contributing 31.4 % of atmospheric Fe on average. In addition, anthropogenic Fe concentration resolved by PMF was comparable to the simulation results of the CMAQ (Community Multiscale Air Quality) and GEOS-Chem (Goddard Earth Observing System-Chemical transport) models, with better correlation to CMAQ (r = 0.76) than GEOS-Chem (r = 0.26). This study developed a new method to estimate atmospheric soluble Fe, which integrates Fe source apportionment results and Fe solubility from different sources. Soluble Fe concentration was estimated as 3.93 ± 5.14 ng/m3, of which 87.0 % was attributed to anthropogenic emissions. Notably, ship emission alone contributed 27.5 % of soluble Fe, though its contribution to total Fe was only 2.2 %. Finally, the total deposition fluxes of atmospheric Fe (37.11 ± 38.43 μg/m2/day) and soluble Fe (1.85 ± 2.13 μg/m2/day) were estimated. This study developed a new methodology for quantifying contribution of anthropogenic emissions to Fe in marine aerosol, which could greatly help the assessment of impacts of human activities on marine environment.

FePO4 preparation and residue recycling by co-processing of steelmaking slag and steel pickling waste liquor: Comprehensive utilization of metallurgical wastes

To prepare FePO4 and to achieve resource utilization of metallurgical wastes, a collaborative treatment of P-bearing steelmaking slag and steel pickling waste liquor (SPWL) was proposed. The utilization of SPWL as a leachant for P separation from steelmaking slag facilitates P-removal residue recycling within steel plants, while also serving as a Fe source for the FePO4 preparation. In this study, the effects of synthetic SPWL with various Fe2+ (or Fe3+) contents and leaching parameters on the dissolution behavior of steelmaking slag were investigated. Moreover, the impacts of H2O2 oxidation and pH on the precipitation behavior of FePO4 from leachate were studied. It was found that increasing Fe2+ concentration in SPWL resulted in a marginal reduction in the P dissolution ratio; however, it was significantly influenced by the pH and solid/liquid ratio. Furthermore, the change in Fe3+ concentration within SPWL exhibited a conspicuous impact on the P dissolution ratio. After leaching, the residue containing massive Fe2O3, MgO, and MnO could be reused as a flux within the steelmaking process. The FePO4 precipitated predominantly at pH 2.0 ∼ 3.0, and the crude FePO4 product containing 42.6 % Fe2O3 and 35.8 % P2O5 was obtained, providing a new solution for the utilization of metallurgical wastes.

Lead in the Presence of Iron under Alkaline Conditions for the Oxygen-Evolution Reaction.

The oxygen-evolution reaction (OER) is a bottleneck in water splitting, which is a critical process for energy storage. In this study, the electrochemistry of Pb in the absence or presence of K2FeO4, as a soluble Fe source, is examined at pH ≈ 13. Our findings indicate that Pb exhibits limited catalytic activity for the OER under alkaline conditions. However, upon the addition of K2FeO4 to the electrolyte, a significant enhancement in the OER activity is observed in the presence of Pb. A notable observation in this study is the formation of stable Fe(IV) species following the OER during chronoamperometry experiments conducted in an alkaline solution. In addition to in situ Raman and visible spectroscopies, the operated electrodes have been characterized by high-resolution transmission electron microscopy, scanning electron microscopy, electron spin resonance spectroscopy, X-ray diffraction, electrochemical methods, electron paramagnetic resonance, and X-ray absorption spectroscopy. Through our experimental investigations, it is consistently observed that the presence of Fe ions on the surface of Pb/PbOx serves as an effective catalyst for the OER. However, it is important to note that this heightened OER activity is only temporary due to the low adhesion of Fe ions on the surface of Pb/PbOx.

Improving the growth, yield and iron concentration of strawberry using sodium hydrosulfide (NaHS) under soilless culture

Required iron (Fe) for the growing plants in soilless culture could be obtained from various Fe sources such as chelates and ferrous sulfate (FeSO4). Despite the low cost of FeSO4, this source is rarely used due to the low Fe solubility at a high pH. Here, the role of sodium hydrosulfide (NaHS) in improving growth and iron availability in strawberry (Fragaria × ananassa cv. Paros) grown in FeSO4 culture solution was reported. The plants were grown hydroponically with two Fe sources, Fe-EDTA and FeSO4 along with three levels (0, 0.2, and 0.5 mM (of H2S donor, NaHS. The results showed that vegetative growth and yield of strawberry under FeSO4 source were lower than Fe-EDTA treated plants. Using NaHS significantly improved vegetative and reproductive growth, yield, chlorophyll SPAD value, maximum efficiency of photosystem II (Fv/Fm), and Fe availability of strawberries under FeSO4 source. Exogenously applied NaHS reduced the hydrogen peroxide (H2O2) and malondialdehyde (MDA) production and electrolyte leakage (EL) in the leaves by enhancing enzymatic antioxidant activity (ascorbate peroxidase, superoxide dismutase, and catalase) in FeSO4 source. Moreover, NaHS affected fruit yield under Fe-EDTA utilization and showed a significant increase in yield amount (by 29.75%) compared to control. In general, there were no significant differences between the two levels of NaHS, 0.2 and 0.5 mM. Our results indicated that H2S affects the maintenance of cell membrane integrity and subsequently iron availability by strengthening the enzymatic antioxidant system and reducing oxidative stress.

Preparation of Fe, N co-doped oxygen reduction catalysts from sacrificial templates and their application to Zn-air batteries

Fe, N co-doped non-precious metal oxygen reduction catalysts has been prepared with nitrogen-rich precursor material (g-C3N4) as a self-sacrificing template and N source. The utilization of g-C3N4 as a nitrogen-rich material could anchor the Fe source sufficiently on its surface, and form abundant active sites. The g-C3N4-derived carbon has a high specific surface area, which facilitates the more active sites to be exposed, and the suitable pore structure provides a site for the oxygen reduction reaction. The half-wave potential of the catalyst is optimized to 0.85 V by doping with different Fe-content sources, exceeding that of commercial 20% Pt/C catalysts. The prepared catalysts also exhibit excellent electron transfer numbers along with superior methanol resistance. The prepared catalysts is loaded into Zn-Air battery devices and presenting high open-circuit voltage, power density, and specific capacitance performance. This work provides an economical and feasible preparation strategy to explore nitrogen-rich precursor materials as Fe-N-C type efficient oxygen reduction catalysts.

Construction of a porous pyrite cinder-supported Mn-doped BiFeO3 composite photocatalyst: Confined-space strategy, structure, and visible-light catalytic degradation toward ciprofloxacin

A series of novel confined visible-light catalysts, namely, Mn-doped BiFeO3 (MBFO) composite photocatalyst anchored on porous residue pyrite cinder (PR-PyC) after partial Fe extraction (PR-PyC/MBFO-φ, φ refers to the doped amount of Mn), was successfully constructed via confined-space strategy using the Fe extracted from PyC as Fe source for BiFeO3 (BFO) and the PR-PyC as the template and structure regulator for MBFO generation. The resulting PR-PyC/MBFO-5% is composed of relatively uniform nanoparticles anchored in the channels of PR-PyC matrix and interparticle interstices and has a specific surface area of 14.18 m2/g, an average pore size of 37.76 nm, and a pore volume 0.13 cm3/g. It has a type-II heterojunction with a band gap energy (Eg) of 1.95 eV and exhibits high visible-light catalytic degradation activity toward ciprofloxacin (CIP) and excellent recyclability. The CIP degradation rate of PR-PyC/MBFO-5% reached 96.41% with an apparent reaction rate constant kapp of 0.0265 min−1 under visible-light irradiation for 120 min, and the corresponding mineralization rate reached 77.42%. The active species produced during photocatalysis were h+ and •OH, in which h+ plays a major role. The doping of 5% Mn can effectively regulate the energy band structure and heterojunction type and the use of an appropriate amount of PR-PyC can effectively guide and regulate the structure and morphology of the as-prepared catalyst. This study presents an effective confined-space strategy for fabricating innovative high-efficiency photocatalysts for antibiotic degradation, thereby paving the way for the valuable resource utilization of PyC.

Biogeochemistry of iron in coastal Antarctica: isotopic insights for external sources and biological uptake in the Amundsen Sea polynyas

Seasonal phytoplankton blooms in the Antarctic Amundsen Sea Polynyas are thought to be supported by an external supply of iron (Fe) from circumpolar deep waters, benthic sediments, and/or ice shelf meltwaters. However, largely due to the limited amount of Fe data reported for the Amundsen Sea Polynyas, understanding of the sources and processes that affect the biogeochemistry of Fe in this region (notably within the ice shelf system) remains limited. Here, we present the first investigation of dissolved Fe isotope distributions (δ56Fe) along the conveyer belt of waters into and through the Amundsen Sea, via the Dotson Ice Shelf, from samples collected during austral summer (2017–2018). Our dataset allows us to characterize and compare the dissolved δ56Fe signatures of incoming modified Circumpolar Deep Water (mCDW) and of sedimentary sources on the continental shelf. The range in dissolved δ56Fe (–1 to +0.1 ‰) observed in the Amundsen Sea close to the seafloor, coupled with elevated dissolved Fe concentrations (up to 1.6 nmol/L), suggests that Fe is released from shelf sediments via a combination of reductive and non-reductive processes, with non-reductive dissolution input being relatively more important (20–56 %) than reductive dissolution (4–12 %). Near the Dotson Ice Shelf, the δ56Fe in the mCDW inflow (–0.70 ‰) was lower than the mCDW outflow (–0.23 ‰), whereas any change in dissolved Fe concentrations was negligible. We speculate that this shift in dissolved δ56Fe underneath the ice shelf is driven by a combination of enhanced preservation (and addition) of lithogenic colloidal Fe(III) and/or complexation with Fe-binding ligands, together with a differential loss of Fe2+. We also found distinct δ56Fe signatures in surface waters of the polynya, with apparent preferential uptake of isotopically light Fe in a bloom dominated by diatoms leading to a relatively heavy remnant dissolved δ56Fe signature of +1.06 ‰, compared to a bloom dominated by haptophytes where more modest and variable isotope fractionation was observed. The different isotopic composition between the two regions could be related to the dominance of different species, but this remains speculative. Despite prominent biological uptake, we suggest that other factors such as rapid recycling (e.g., adsorption and regeneration), bacterial regeneration, and complexation with organic ligands, together with the supply of lithogenic particles also play important roles in setting surface dissolved δ56Fe in the Amundsen Sea Polynyas. Overall, this study provides a further understanding of the external Fe sources and the biogeochemical processes in the Amundsen Sea and thus a baseline on how changing conditions in Antarctica can affect Fe cycling in the Southern Ocean and beyond.

Structural and Magnetic Properties of SrFe12O19 Ferrites Obtained by Using α-Fe2O3 Particles with Different Morphology as Fe Source

Structural and Magnetic Properties of SrFe12O19 Ferrites Obtained by Using α-Fe2O3 Particles with Different Morphology as Fe Source

Phosphate burial in aquatic sediments: Rates and mechanisms of vivianite formation from mackinawite

Excess phosphorus abundance often drives eutrophication and affects surface water quality. Formation of vivianite (Fe3(PO4)2 • 8H2O) in aquatic sediments acts as a significant sink for phosphate (P), crucial for resorting surface waters. Authigenic vivianite formation, however, can be limited by other ferrous iron containing phases, in particular iron sulfides. Although thermodynamically feasible under suitable conditions, the formation of vivianite from mackinawite has been widely disregarded for authigenic phosphate mineral formation. Here we investigated the formation of vivianite from mackinawite (FeS) in batch experiments in which dissolved sulfide was continuously removed, at P levels between 0 – 5 mM in a pH of 6 to 8. Solid characterizations by electron microscopy, X-ray diffraction as well as Mössbauer and X-ray absorption spectroscopy demonstrates that vivianite was formed at all pH values in P amended experiments. The temporal evolution of dissolved Fe(II) concentrations indicates that the transformation proceeds via the release of the dissolved Fe(II) by FeS dissolution and subsequent vivianite precipitation, over time scales of days. The kinetics of the transformation are controlled by the dissolution rates of FeS. Aging and transformation of FeS, however, compete with vivianite formation. Aging is more pronounced at higher pH but is inhibited by P adsorption. Hence, the effect of pH and P concentration on aging is the main reason for the influence on these parameters on the rates and extent of vivianite formation. Our findings demonstrate that FeS can be an effective iron source for vivianite formation in aquatic sediments when sulfide concentrations decrease due to, for example, changes in external forcing or microbial sulfide oxidation. Formation of vivianite from FeS as an Fe source can also open new perspectives in P recovery in water treatment, for example when Fe is added to digesters to bind H2S.

The fingerprint of climate variability on the surface ocean cycling of iron and its isotopes

Abstract. The essential micronutrient iron (Fe) limits phytoplankton growth when dissolved Fe (dFe) concentrations are too low to meet biological demands. However, many of the processes that remove, supply, or transform Fe are poorly constrained, which limits our ability to predict how ocean productivity responds to ongoing and future changes in climate. In recent years, isotopic signatures (δ56Fe) of Fe have increasingly been used to gain insight into the ocean Fe cycle, as distinct δ56Fe endmembers of external Fe sources and δ56Fe fractionation during processes such as Fe uptake by phytoplankton can leave a characteristic imprint on dFe signatures (δ56Fediss). However, given the relative novelty of these measurements, the temporal scale of δ56Fediss observations is limited. Thus, it is unclear how the changes in ocean physics and biogeochemistry associated with ongoing or future climate change will affect δ56Fediss on interannual to decadal timescales. To explore the response of δ56Fediss to such climate variability, we conducted a suite of experiments with a global ocean model with active δ56Fe cycling under two climate scenarios. The first scenario is based on an atmospheric reanalysis and includes recent climate variability (1958–2021), whereas the second comes from a historical and high-emissions climate change simulation to 2100. We find that under recent climatic conditions (1975–2021), interannual δ56Fediss variability is highest in the tropical Pacific due to circulation and productivity changes related to the El Niño–Southern Oscillation (ENSO), which alter both endmember and uptake fractionation effects on δ56Fediss by redistributing dFe from different external sources and shifting nutrient limitation patterns. While the tropical Pacific will remain a hotspot of δ56Fediss variability in the future, the most substantial end-of-century δ56Fediss changes will occur in the Southern Hemisphere at middle to high latitudes. These arise from uptake fractionation effects due to shifts in nutrient limitation. Based on these strong responses to climate variability, ongoing measurements of δ56Fediss may help diagnose changes in external Fe supply and ocean nutrient limitation.

Fe-doped two-dimensional graphite carbon nitride: An effective nanozymetic catalyst for electrochemical detection of cell-released H2O2

In this work, a simple one-step pyrolysis process was designed to synthesize Fe-doped graphite carbon nitride (Fe–C3N4) nanosheets with FeCl3 as Fe source. The resulted samples were characterized by various characterization techniques, and the results showed that Fe species might form Fe–N bonds with N atoms of C3N4, which was similar to the iron (II) porphyrin active center of horseradish peroxidase. Then Fe–C3N4 nanosheet was further mixed with carbon nanotube (CNT) to obtain Fe–C3N4@CNT nanocomposite, which was further modified on the self-made flexible printed electrode (PE) to construct the flexible working electrode. Fe–C3N4 nanosheets show good catalytic activity for H2O2 and the introduction of CNT can effectively improve the electron transfer efficiency at the modified electrode interface. By combining with wireless portable electrochemical workstation, the sensor shows a wider detection range (10.0 μmol L−1–20.0 mmol L−1) and a lower limit of detection (0.38 μmol L−1, S/N = 3) for the H2O2 analysis. Furthermore, the sensor can be applied to the real time and in-situ analysis of H2O2 secreted from live cells. In word, this self-supported sensing electrode shows great potential applications in monitoring the pathological and physiological dynamics of cancer cells.

Assessment of potential risks to human health associated with trace elements in three commercially important shark species captured in the Central Mexican Pacific.

Shark meat is a popular protein source worldwide. However, existing national control policies for ensuring the safety and quality of shark meat are minimal. There are concerns about the sustainability of shark populations, which bioaccumulate and biomagnify potentially toxic elements at higher rates than non-predatory fish, posing a risk to human health. In this study, the contributions of essential elements to the Recommended Dietary Allowance (RDA) and potentially toxic elements to the Reference Dose (RfD) linked to shark consumption (200g per week) were investigated for three shark species in the Central Mexican Pacific. We estimated risks and benefits for women, children, and men. Our results suggest that the three shark species are sources of Se, Co, Cr, Cu, Fe, and Zn, but poor sources of Mn for women and men aged 19-50years. A weekly ingestion of 200g of shark meat exceeded the RfD-As by 4-14 times and the RfD-Pb by 1.1-1.7 times for adults, indicating a potential risk to human health. The three shark species were also significant sources of potentially toxic elements for children, including Hg, Cd, Cr, and Pb. An excessive intake of Se was observed, with levels at 8.4-10.6 and 4.3-5.3 times the RDA for children aged 1-8 and 9-13years, respectively. Although shark meat can be a good source of essential nutrients, the lack of controls in the commercialization process indicates that it should be consumed in moderation due to the potential risks associated with excessive exposure to potentially toxic elements. This caution is particularly important for children and pregnant women, who are at higher risk of health complications from consuming contaminated food.

Inorganic and Organic Fe Sources Increased Crude Oil Biodegradation in Soil Under Cultivation of the Canola Plant Inoculated with Piriformospora indica

Inorganic and Organic Fe Sources Increased Crude Oil Biodegradation in Soil Under Cultivation of the Canola Plant Inoculated with <i>Piriformospora indica</i>

The Effect of Zinc and Iron Applications from Different Sources to Growth, Dry Matter, and Its Uptake by Lettuce (Lactuca sativa)

Zinc (Zn) and iron (Fe) are among the micronutrients humans need. However, the main food sources in developing countries such as Malaysia have low micronutrients, making it insufficient to supply the minimum daily requirement. Foliar fertilization is one of the most effective and safe ways to enrich important micronutrients in plants. This study investigated variations in Zn and Fe sources to evaluate the effects of individual Zn and Fe foliar applications on growth, dry matter, and nutrient uptake by lettuce (Lactuca sativa). Based on the result, the application of Zn and Fe in the form of sulfate salt showed a lower toxicity effect in terms of growth and dry matter of plants than Fe and Zn in the form of ethylenediaminetetraacetic acid (EDTA). In terms of Zn uptake, it was found that there was a significant difference observed compared to the control, especially when 3 kg/ha Zn was applied, regardless of whether it was in the form of sulfate or EDTA. Furthermore, there was an increase in Fe uptake observed with increased Zn application. In contrast, the Fe application showed no difference in Fe intake compared to the control. It was found that there is a decrease in Zn uptake observed with increasing application of Fe rate. Sufficient Fe content is already available in the soil, and plants only take up what is needed for growth.

Synthesis of dual-modified Fe-doped and carbon-coated Li4Ti5O12 anode based on industrial H2TiO3 for Li-ion batteries

Spinel Li4Ti5O12 (LTO) is a promising candidate for lithium-ion battery anodes because of its exceptional stability and safety. However, its extensive application is limited by a high comprehensive cost, poor electronic conductivity, and other inherent defects. This work presents a novel synthesis procedure to synthesize carbon-coated Fe-doped LTO composites through carbon reduction, in the presence of Fe-containing industrial H2TiO3 as the titanium source, and glucose as the carbon source. The presence of the Fe-dopant is confirmed through XRD, with Rietveld refinement and EDS experiments. Results show that Fe2+ replaces a portion of Ti4+ after doping, leading to an increase in the LTO cell parameters and the corresponding cell volume. FLTO/C, presents a capacity of 153.79 mAh g−1 at 10 C, and the capacity decay per cycle is only 0.0074% after 1000 cycles at 5 C. Moreover, EIS experiments indicate that the incorporation of Fe and carbon lowers the charge transfer resistance and improves the diffusion and migration of Li+. Notably, since this preparation process requires no additional Fe source as a raw material, it is simple, cost-effective, and suitable for large-scale production and further application.

Spontaneous corrosion on the surface: Ni-regulated oxalates grown in situ on stainless steel for efficient oxygen evolution

Bimetallic NiFe-based materials are widely certified for their high performance in the oxygen evolution reaction (OER). In this work, a hydrothermal method was used to activate stainless steel (SS) with oxalic acid. The SS was used as the Fe source and carrier, and the in situ-grown NiFe oxalate microcrystals were synthesized by introducing a certain percentage of nickel to modulate the crystallographic appearance. In the crystal, the doped Ni couples with the surrounding Fe, prompting coordination defects in the lattice and generating more active vacancies. Meanwhile, the lattice deformation hinders the further stacking of the crystals, and the morphology of oxalates is regulated. This phenomenon is beneficial to optimize the intermediate adsorption step. In addition, the oxalate anions with strong complexation ability prevent the dissolution of the active substances during the catalytic process. Hence, NIO-SS electrode require only 315 mV and 391 mV of overpotential to achieve current densities of 50 and 100 mA·cm−2. At the same time, the stability of 100 h is maintained. This work presents a novel idea to improve the OER performance of stainless steel by spontaneous corrosion and Ni-regulated of the generated oxalates, promising to be used in actual production.