Oxyhydroxide Research Articles

Transcription factors dealing with Iron-deficiency stress in plants: focus on the bHLH transcription factor family.

Iron (Fe), as an important micronutrient element necessary for plant growth and development, not only participates in multiple physiological and biochemical reactions in cells but also exerts a crucial role in respiration and photosynthetic electron transport. Since Fe is mainly present in the soil in the form of iron hydroxide, Fe deficiency exists universally in plants and has become an important factor triggering crop yield reduction and quality decline. It has been shown that transcription factors (TFs), as an important part of plant signaling pathways, not only coordinate the internal signals of different interaction partners during plant development, but also participate in plant responses to biological and abiotic stresses, such as Fe deficiency stress. Here, the role of bHLH transcription factors in the regulation of Fe homeostasis (mainly Fe uptake) is discussed with emphasis on the functions of MYB, WRKY and other TFs in the maintenance of Fe homeostasis. This review provides a theoretical basis for further studies on the regulation of TFs in Fe deficiency stress response.

Environmental impact of fouling for crude oil flow in preheat pipes according to oil blends

Crude oil fouling is a complex process caused by multiple mechanisms. This study examined fouling's environmental impact on a distillation unit's heating tubes and heat exchangers, proposing optimal pollution levels to reduce emissions and achieve sustainability goals. The study evaluated five crude oil blends in terms of API, sulphur, salt content, and other physical properties. Contaminated water was analyzed through biological and chemical means, while CO2, NOx, and SOx emissions were calculated from actual fuel and power consumption. Solid and sludge sediments were observed throughout all plate heat exchangers, consisting primarily of iron hydroxides and manganese oxides. Rationalizing energy use reduced the burden on the environment and fuel consumption by 7 %, with a 2 % reduction in energy needed to refine crude oil feeding units when fouling is removed after maintenance. By optimizing pollution levels and reducing energy consumption, the environmental impact of fouling can be mitigated.

Long-term phosphorus removal by Ca and Fe-rich drainage filter materials under variable flow and inlet concentrations

Phosphorus (P) losses from tile-drained agricultural fields may degrade surface water quality by accelerating eutrophication. Among the different edge-of-field technologies, compact filter systems using different filter materials have been identified as potentially effective solutions for removing P from drainage water before discharge downstream.This study investigated the long-term (>696 days) P removal efficiency of 5 different filter materials in a column setup, using artificial drainage water (pH 6). Filter materials included two iron-based granulates (calcinated diatomaceous earth (CDE), ferric hydroxide granules (CFH)), and three calcium-based granulates (seashells, limestone, calcinated silicate/calcium oxide (Filtralite-P)). Experiments were performed under variable flow rates (0.037 and 1.52 L h−1; hydraulic retention time of 26–43 min and 18–30 h) and inlet P concentrations (0.14 and 0.7 mg L−1). An overall analysis revealed that the Fe-based materials achieved higher P retention than Ca-based materials. In particular, CFH was capable of retaining 99 and 98 % of the high and low inlet P concentrations, respectively. Conversely, limestone retained only 25 % of the high P load. CDE performed moderately well, independently of the inlet P concentration. Filtralite-P and Seashells performed well at high inlet P concentration but relatively poorly at low P concentration. The sensitivity of filter material P removal efficiency to variations in P loading was generally lowest for CFH and highest for limestone.

Nitrate Reactivity in Iron (Oxy)hydroxide Systems: Effect of pH, Iron Redox State, and Phosphate

Nitrate Reactivity in Iron (Oxy)hydroxide Systems: Effect of pH, Iron Redox State, and Phosphate

Probing the (de)activation of Raney nickel–iron anodes during alkaline water electrolysis by accelerated deactivation testing

We investigated the (de)activation of Raney nickel–iron anodes in various oxygen evolution reaction (OER) environments using accelerated deactivation testing (ADT) under the conditions of on/off voltage control (ADT1), constant current density (ADT2), and cyclic voltammetry (ADT3). ADT1 caused activation under OER conditions by promoting the leaching of residual zinc and thus increasing the electrode surface area and oxygen vacancy content, whereas deactivation was observed under the conditions of the hydrogen evolution reaction(H-ADT1). ADT2 decreased the OER activity by promoting NiO formation and iron leaching, while ADT3 slightly increased the OER activity by favoring the incorporation of iron into the nickel lattice and promoting nickel–iron hydroxide formation. Thus, this work facilitates the design of more efficient and durable Raney nickel–based OER anodes by providing insights into their (de)activation mechanisms.

Efficient selective flotation separation of fluorite from calcite using ferrous and ferric species as combined depressant

It is known that the flotation separation of fluorite/calcite is extremely difficult because of their similar surface features. In this research, the combination of FeSO4·7H2O and Fe2 (SO4)3 (FF) as depressant for possible flotation separation of calcite/fluorite was systematically investigated, with sodium oleate (NaOL) as collector. Besides large gap between mono-mineral flotation results of fluorite and calcite, even for 1:1 mixed sample, CaF2 grade of 80.29 % and CaF2 recovery of 90.79 % of fluorite concentrate can be achieved with FeSO4·7H2O (300 mg/L) and Fe2 (SO4)3 (150 mg/L) used as combined depressant and NaOL (40 mg/L) as collector at pH = 6. In addition to the quantitative micro-flotation results on mono-mineral and artificially mixed sample, SEM-EDS, contact angle measurement, zeta potential measurement, FTIR and XPS analyses, as well as collector adsorption experiment, were carried out to clarify the selective inhibition mechanism. Characterizations confirmed that, under interaction with iron sulfates (FF), ferrous hydroxide, ferric hydroxide, hydroxyl iron oxide and green rust were in-suit generated on calcite surface due to the presence of the hydrolysis of OH− and CO32− on calcite surface, while such Fe-related components were barely discernible on fluorite surface. These different adsorption features for Fe (II) and Fe (III) species on mineral surfaces exactly hindered the complexation of NaOL on calcite surface, while maintained the adsorption of collector on fluorite surface, thereby to realize the selective separation of fluorite from calcite.

The Pilot Study of a Dual-Media Filter Consisting of Mortar and Modified Zeolite for Removing Heavy Metals from Expressway Stormwater Runoff

Stormwater runoff from expressways generally has high concentrations of heavy metals. However, the heavy metal removal of conventional sand filters is low, so a better alternative is required. In this study, several inexpensive materials were tested for their heavy metal adsorption, and the performances of the selected materials were evaluated via field tests. The results of laboratory experiments showed that the Cu adsorption capacity followed the order of Na-zeolite > zeolite > biochar > granular ferric hydroxide > sand ≥ orchid stone. The performance of a pilot-scale dual-media filter filled with Na-zeolite and mortar granules was monitored for four rainfall events at an expressway site, and was compared to that of a sand filter. Both filters showed similar event mean concentration (EMC) removal for BOD, COD, TOC, and T-N, without a notable decrease in hydraulic conductivity. However, the removal of T-P, Cu, Zn, Cr, Ni, and Fe by the dual-media filter was 37.6–74.8%, 59.1–90.1%, 84.9–99.7%, 100.0%, 100.0%, and 78.7–94.4%, respectively, which was up to 4.5 times of that of the sand filter. In addition, it was stable regardless of the influent EMCs. Overall, we showed that the dual-media filter is excellent in heavy metal removal from stormwater runoff, with negligible clogging.

Safe and effective delivery of supplemental iron to healthy adults: a two-phase, randomized, double-blind trial - the safe iron study.

The safety of novel forms of iron in healthy, iron-replete adults as might occur if used in population-based iron supplementation programs was examined. We tested the hypotheses that supplementation with nanoparticulate iron hydroxide adipate tartrate (IHAT), an iron-enriched Aspergillus oryzae product (ASP), or ferrous sulphate heptahydrate (FS) are safe as indicated by erythrocyte susceptibility to malarial infection, bacterial proliferation, and gut inflammation. Responses to FS administered daily or weekly, and with or without other micronutrients were compared. Two phases of randomized, double-blinded trials were conducted in Boston, MA. Phase I randomized 160 volunteers to six treatments: placebo, IHAT, ASP, FS, and FS plus a micronutrient powder (MNP) administrated daily at 60 mg Fe/day; and FS administered as a single weekly dose of 420 mg Fe. Phase II randomized 86 volunteers to IHAT, ASP, or FS administered at 120 mg Fe/day. Completing these phases were 151 and 77 participants, respectively. The study was powered to detect effects on primary endpoints: susceptibility of participant erythrocytes to infection by Plasmodium falciparum, the proliferation potential of selected pathogenic bacteria in sera, and markers of gut inflammation. Secondary endpoints for which the study was not powered included indicators of iron status and gastrointestinal symptoms. Supplementation with any form of iron did not affect any primary endpoint. In Phase I, the frequency of gastrointestinal symptoms associated with FS was unaffected by dosing with MNP or weekly administration; but participants taking IHAT more frequently reported abdominal pain (27%, p < 0.008) and nausea (4%, p = 0.009) than those taking FS, while those taking ASP more frequently reported nausea (8%, p = 0.009). Surprisingly, only 9% of participants taking IHAT at 120 mg Fe/day (Phase II) reported abdominal pain and no other group reported that symptom. With respect to the primary endpoints, few differences were found when comparing these forms of iron, indicating that 28 days of 60 or 120 mg/day of IHAT, ASP, or FS may be safe for healthy, iron-replete adults. With respect to other endpoints, subjects receiving IHAT more frequently reported abdominal pain and nausea, suggesting the need for further study. ClinicalTrials.gov, NCT03212677; registered: 11 July 2017.

Rapid measurement of actinides in urine by mass and alpha spectrometric methods.

To provide timely information for prompting decision-making in emergency radiation therapy, we developed simple and rapid mass and alpha spectrometric methods for urinary bioassays to determine ultra-trace actinide isotopes. For the mass spectrometric method, after organic matter decomposition, LaF3/CaF2 co-precipitation and chromatographic purification using 2ml of AG MP-1M anion exchange resin, U and Pu isotopes were measured in a 20-ml urine sample by inductively coupled plasma-mass spectrometry. In the alpha spectrometric method, after organic matter decomposition, iron hydroxide co-precipitation and chromatographic purification using 2ml of TEVA and 2ml of DGA resin cartridges, Pu, U and Am/Cm isotopes were measured in a 500-ml urine sample by alpha spectrometry. These alpha and mass spectrometric methods were then applied for participation in the 2020 intercomparison organized by the Association for the PROmotion of Quality COntrol in RADiotoxicological Analysis (PROCORAD), France, for method validations.

Preparation of coated MgFe layered double hydroxide nanoparticles on cement kiln dust and intercalated with sodium dodecyl sulfate as an intermediate layer for the adsorption of estrogen from water

Estrogenic hormones, found as micropollutants in water systems, give rise to grave concerns for human health and marine ecosystems, triggering a cascade of adverse effects. This research presents an innovative manufacturing approach using nanoscale layered double hydroxides of magnesium and iron, with sodium dodecyl sulfate surfactant, to create highly efficient sorbent cement kiln dust (CKD) based beads (CKD/MgFe-SDS-LDH-beads). These beads effectively remove estrone from water. Optimization of the preparation process considered factors like molar Mg/Fe ratio, CKD dosage, pH, and SDS dosage using Response Surface Methodology (RSM). The adsorption process was well-characterized by Langmuir isotherm and pseudo-second-order kinetic models, demonstrating a remarkable 6.491 mg/g sorption capacity. Results proved that the calcite was the main component of the CKD with miners of dolomite, and quartz. Adsorption capacity, surface charges, and the availability of vacant sites may be the main mechanisms responsible of removal process. Experimental tests confirmed the beads' potential for estrone removal, aligning with the Bohart-Adams and Thomas-BDST models. This study introduces a promising, eco-friendly solution for addressing water contamination challenges.

Scalable room-temperature synthesis of NiFe oxyhydroxide tailored with S atoms for enhanced oxygen evolution in alkaline seawater and domestic sewage

Developing facile and scalable method to prepare oxygen evolution reaction (OER) catalysts which is suitable for industrial water electrolysis at large operating current densities is vital for green hydrogen production, but still remains a great challenge. Herein, we developed a one-step method to in situ fabricate S-doped NiFe oxyhydroxide (S–Ni(Fe)OOH) ultrathin nanosheet on Ni foam at room temperature, which is suitable for scaled up production, by which a electrode with 500 cm2 can be facilely prepared. The prepared S–Ni(Fe)OOH shows excellent OER stability and activity in 5 M KOH, alkaline sewage and seawater, which only need 198, 275 and 284 mV to reach 500 mA cm−2, respectively. Theoretical calculations indicated that the incorporation of S modulates the chemisorption of oxygen-containing intermediates and facilitates the evolution from ∗OH to ∗O, thus enhance the intrinsic OER activity of S–Ni(Fe)OOH. The electrolyzer based on S–Ni(Fe)OOH can reach a current density of 100 mA cm−2 at a small cell voltage of 1.56 V in 1 M KOH, much smaller than the benchmark catalyst Pt/C||IrO2(1.87 V). This work provides a facile method to prepare highly efficient catalyst for alkaline sewage and seawater oxidation, which could provide references to the development of catalyst for practical hydrogen production.

Sorption of Selenium(IV) and Selenium(VI) onto Iron Oxide/Hydroxide-Based Carbon Materials: Activated Carbon and Carbon Foam

Selenium pollution in water is a worldwide issue. Se(IV) and Se(VI) are mainly found in contaminated water due to their high solubility and mobility; their presence poses a serious risk as they can severely harm human health. Although iron oxide and hydroxide nanoparticles can be efficient candidates for the removal of selenium oxyanions due to their high adsorption capacity, the role of each iron species has not been fully elucidated. Furthermore, iron species are often found to be less effective for Se(VI) than Se(IV). The challenge and novelty of this study was to develop a carbon material impregnated with different iron phases, including oxides (magnetite/hematite) and hydroxides (goethite/lepidocrocite) capable of removing both Se(IV) and Se(VI). Since the phase and morphology of the iron nanoparticles play a significant role in Se adsorption, the study evaluated both characteristics by modifying the impregnation method, which is based on an oxidative hydrolysis with FeSO4 7H2O and CH3COONa, and the type of carbonaceous support (activated carbon or sucrose-based carbon foam). Impregnated activated carbons provide better removal efficiencies (70–80%) than carbon foams (&lt;40%), due to their high surface areas and point zero charges. These results show that the adsorption of Se(VI) is more favorable on magnetic oxides (78%) and hydroxides (71%) than in hematite (&lt;40%). In addition, the activated carbon decorated with magnetite showed a high adsorption capacity for both selenium species, even in alkaline conditions, when the sorbent surface is negatively charged. A mechanism based on the adsorption of inner-sphere complexes was suggested for Se(IV) immobilization, whereas Se(VI) removal occurred through the formation of outer-sphere complexes and redox processes.

Effect of the Grain Refinement of Iron(III) Hydroxide Precipitation for Removal of Chromium(III) by Iron(III) Hydroxide Coprecipitation Method for Chromium(VI) Determination

Effect of the Grain Refinement of Iron(III) Hydroxide Precipitation for Removal of Chromium(III) by Iron(III) Hydroxide Coprecipitation Method for Chromium(VI) Determination

The Production of Hematite Powder from Spent Pickling Hydrochloric Acid

This research aimed to study the recycling process and the feasibility of recovering iron as hematite or red oxide powder (Fe2O3) from spent pickling acid (hydrochloric acid). The spent hydrochloric acid waste from the pickling bath in the sheet rolling steel industry contains approximately 233 g of iron dissolved in one liter of the spent acid. To recover iron, 2 M NaOH was added to the spent acid until reaching pH 7. The iron was precipitated as iron oxide and/or hydroxide. Next, the oxidation of ferrous oxide was carried out by adding H2O2 35%v/v to control the shade color. The precipitates were subsequently separated from the acid solution by a filter press. The precipitates were dried at 110°C for 24 h and calcined at 700°C for 2 h to synthesize and modify the crystallinity of ferric oxide. Ferric oxide was subject to water washing, where contaminating sodium chloride could be dissolved and filtered out. After drying at 110°C for 24 h, high-purity hematite was achieved. Hematite recovered from the spent pickling acid via this process provided more than 97% purity at 94.4% recovery.

Multi-metal contaminant mobilizations by natural colloids and nanoparticles in paddy soils during reduction and reoxidation

Naturally-occurring colloids and nanoparticles are crucial in transporting heavy metal contaminants in soil-water systems. However, information on particle-bound metals’ size distribution and elemental composition in paddy soils under redox-fluctuation is scarce. Here, we investigated the mobilization of Cu, Cd, and Pb-containing nanoparticles and colloids in four contaminated soils with distinctive geochemical properties during reduction and subsequent re-oxidation. Using AF4-UV-ICP-MS and STEM-EDS, we observed that particle-bound metals were primarily associated with two sizes ranges: 0.3−40 kDa (F1) and 130 kDa−450 nm (F2), which mainly consisted of organic matter (OM), iron hydroxide and clay minerals. Cu and Pb were more likely bound to colloid than Cd. Colloidal Cu, Pb and Cd accounted for averages of 83.2%, 72.4% and 19.8% of their total concentration in solution (<0.45 µm) during soil reduction, and decreased during soil re-oxidation. This proportion was also positively correlated with aqueous pH and DOC but negatively correlated with Eh. Further quantitative analysis demonstrated that Cu/Cd positively correlated with OM at nanometric scale (F1). This study provides quantitative insights into the size, composition and abundance of polymetallic pollutant-carrying particles in paddy soils during redox fluctuation, and highlights the importance of nanometric interactions between OM and toxic cationic metals for their release.

Research and development of gold ore processing technology

This paper presents the results of technological studies of two samples of gold-bearing ore from the gold-bearing deposit of Kazakhstan deposits 1 and 2. A comprehensive analysis of ore samples by X-ray fluorescence, X-ray phase, chemical, and mineralogical methods was carried out. The calculated initial gold content was determined, and X-ray fluorescence analysis showed that the main elements that make up the ore are oxygen up to 51% and silicon up to 33%. X-ray phase analysis showed the presence of more than 95% quartz and muscovite in the samples. The form of finding gold in the ore, according to the results of mineralogical analysis, is defined as free gold and gold in iron hydroxide. Silver is present in the studied samples in the form of various types of halides. An ore beneficiation scheme has been developed and presented, including gravity and flotation. Gravity enrichment was carried out in two stages, with the production of concentrate and tailings, with the maximum recovery of gold in concentrate up to 91%, flotation enrichment using butyl xanthate reagents and a blowing agent, was carried out in two stages with the production of main and control concentrates and final flotation tailings. The subsequent hydrometallurgical study of the ore was carried out to assess the effect of sodium cyanide on the extraction of gold, tests were performed on the leaching of the initial samples of the ore and the obtained flotation and gravity concentrates in the agitation mode, it was found that cyanide leaching is an effective method for processing the mineral raw materials of the gold-bearing deposit of Kazakhstan, and the obtained flotation concentrates, with the recovery of gold into solution under optimal conditions up to 98%. The results obtained make it possible to predict the effectiveness of the main technological stages in the ore processing scheme, technology optimization, and maximum gold recovery.

EFFECT OF POLYMER MODIFIER ON THE MOR­PHO­LOGICAL AND SEPARATION PROPERTIES OF ASYMMETRIC MICROFILTRATION MEMBRANES

Modifying membranes is a common approach to improve their separation ability. In this work, a series of the membranes, which reject colloidal particles of a wide diapason of their size, was obtained by modifying acetylcellulose microfiltration membranes with such rigid polymer as polymetylmetacrilate. Modifying was carried out by precipitation of the polymer in the membrane pores, the depo­sition occurred from the solutions of different concentrations. Other way was multistage modifying membranes with a solution of the same concentration. Depending on the modifying conditions, the content of polymetylmetacrilate in the membrane was 12–44 %. Morphology of the composite membranes was investigated by optical and scanning electron microscopy. Water test was also performed at 0.5–2 bar. The membranes obey Darcy law in this pressure diapason: thus, the pore radius can be approximately estimated from the Hagen – Poiseuille equation (18–63 nm). Moreover, the modifier minimizes the membrane compression: a decrease of the permeate flux is 19 % (pristine membrane) and 8% for membranes containing high amount of the modifier. Colloidal solutions of water-soluble linear polymer, vegetable protein and sol of hydrated iron oxide were also used for the membrane testing. The selectivity of composite membranes enhances in the row: polyvinylpyrollidone &lt; iron oxide &lt; albumin. In the case of vegetable protein, the membrane selectivity is 30–91% depending on the modifier content. The membrane with highest separation ability was used for clarification of goiaba juice: the selectivity towards total solids was found to reach 33–73%. The permeate can be used for the production of beverages, the concentrate is recommended for confectionery industry. Polymethylmetacrylate can be recommended for the membrane modifying as a binding component in the composite containing also hydrophilic agent.

SYNTHESIS AND STUDY OF NANO-SIZED COMPLEX OF Fe(III) WITH ETHYLENEDIAMINEDISUCCINIC ACID

In this work, the FeEDDSNP nanocomplex was synthesized by dissolution peptization of a freshly precipitated sol of iron hydroxide Fe(OH)3 in an aqueous solution of the racemic form of Н4EDDS. The complex was characterized by electron absorption spectroscopy and IR spect­roscopy. It was shown that the structure of the nanocomplex is identical to the structure of the FeEDDS complex obtained using a two-stage technology. The position of the absorption maxima of iron nanoparticles practically does not change depending on the sto­rage time at room temperature, which indicates the stability of the synthesized nanocomplex. The nano­dispersed FeEDDSNP complex is more soluble in water (275 g/l) compared to the FeEDDS complex obtained by the classical method (150 g/l), which greatly facilitates its use as a biologically active compound. To determine the stability of the system depending on the pH, the electrokinetic potential was measured to select the optimal pH of the medium and concentrations to obtain stable dispersed systems. It is shown that at low pH (1.5–4.0) there is a drop in the electrokinetic potential, and when the pH increases, the

Magnetic-field-assisted electrodeposition regulates the Ni:Fe ratio for water oxidation

Nickel iron (oxygen) hydroxide (NiFeOx(OH)y) has been extensively studied as a promising electrocatalyst for oxygen evolution reaction (OER). Reasonable control of the ratio of Ni to Fe can improve its catalytic performance but has not yet been effectively achieved. In this work, we designed a magnetic-field-assisted electrodeposition method, which combined the magnetohydrodynamic effect and the corrosion effect of nickel foam substrate in the electrolyte to adjust the mass transfer and surface microenvironment (pH), thereby adjusting the Ni and Fe ratio in a large range. As a result, we use the foamed nickel substrate as the nickel source. As the deposition magnetic field increases, the composition of the catalyst evolves from Ni-doped FeOOH (Ni–FeOOH) to Ni–FeOOH/Ni(OH)2 p-n junction. The introduction of Ni and the p-n junction are beneficial to the electron transfer during the OER process. The sample Ni–FeOOH/Ni(OH)2-500 has an overpotential of only 264 mV at a current density of 20 mA/cm2, which is 34 mV lower than Ni–FeOOH-0.

Application of PEG-Fe3O4 nanofluid in flat-plate solar collector: An experimental investigation

In the present study, novel in-situ oxidation precipitation of ferrous hydroxide method is used to synthesized Fe3O4 nanoparticles and Polyethylene glycol 200 is used for covalent functionalization. Various characterizations tests (FESEM, EDX, XRD, FTIR, HRTEM) were performed, and the Polyethylene glycol treated Iron oxides functionalization was confirmed. Thermal conductivity, density, specific heat, and viscosity were experimentally assessed and validated using the correlations that were available. The corresponding improvements in thermophysical characteristics were 13.35%, 0.06%, 0.37%, and 20.9% at 0.1 wt% and 35°C. UV–vis spectroscopy and Zeta protentional was used to check the stability of nanofluids and found that nanofluid was stable for 30 days. A flat plate solar collector was experimentally installed, and the thermal performance of collector was calculated using ferrofluid under ASHRAE standard 93–2003 at different heat flux intensities (597,775,988 W/m2), mass flow rates ((0.0133, 0.0200, 0.0266 kg/s), inlet fluid temperature (30–50°C) and weight concentrations (0.025,0.05,0.075,0.1%). The highest thermal efficiency enhancement of 13.83% was noticed. Moreover, the ANSYS-CFD model was used for the numerical analysis of the thermal performance of flat plate collector at the same environmental conditions, and a maximum difference of 8.33% at 0.1 wt% was noticed in comparison with experimental data.