Kinetics Of Reduction Research Articles

Steric hindrance and orientation polarization by a zwitterionic additive to stabilize zinc metal anodes

AbstractZinc metal stands out as a promising anode material due to its exceptional theoretical capacity, impressive energy density, and low redox potential. However, challenges such as zinc dendrite growth, anode corrosion, and side reactions in aqueous electrolytes significantly impede the practical application of zinc metal anodes. Herein, 3‐(1‐pyridinio)‐1‐propanesulfonate (PPS) is introduced as a zwitterionic additive to achieve long‐term and highly reversible Zn plating/stripping. Due to the orientation polarization with the force of electric field, PPS additive with π–π conjugated pyridinio cations and strong coordination ability of sulfonate anion tends to generate a dynamic adsorption layer and build a unique water–poor interface. PPS with steric hindrance effect and strong coordination ability can attract solvated Zn2+, thereby promoting the desolvation process. Moreover, by providing a large number of nucleation sites and inducing zinc ion flow, the preferred orientation of the (002) crystal plane can be achieved. Therefore, the interfacial electrochemical reduction kinetics is regulated and uniform zinc deposition is ensured. Owing to these advantages, the Zn//Zn symmetrical cell with PPS additive exhibits remarkable cycling stability exceeding 2340 h (1 mA cm−2 and 1 mA h cm−2). The Zn//V2O5 full cell also delivers stable cycling for up to 6000 cycles.

A kinetic comparison between in situ hybrid microwave and conventional magnetising roasting of low-grade iron ore composite pellet

This article aims to comprehensively summarise the essential aspects of reduction kinetics in magnetising roasting of low-grade iron ore–coal composite pellets in the hybrid microwave and conventional furnace. The influence of crucial process parameters like temperature, time, and heating methods, including traditional and hybrid microwave heating, is explored. Investigating the impact of low-grade iron ore and coal quality on reduction kinetics is conducted to identify optimal heating methods for upgrading low-grade iron ore to blast furnace grade through magnetising roasting. The study uses diverse gas–solid reaction models to assess the reduction mechanism (Fe2O3 to Fe3O4). Results indicate the success of the contracting volume model for microwave heating, while conventional heating transitions from phase-boundary chemical control to diffusion control. XRD confirms magnetite dominance post-reduction, while scanning electron microscopy analysis establishes microwave crack-assisted efficiency over conventional heating for ease of reduction. A comparative study of apparent activation energy reveals the hybrid microwave method's four-fold lower (36.71 kJ/mol) than conventional resistance heating (156.19 kJ/mol). This underscores the potential of microwave heating for enhanced reduction kinetics and low-grade iron ore material processing applications.

Manufacturing of heavy tungsten alloys from nano-sized metal oxides via simultaneous reduction-sintering powder treatments

Heavy tungsten alloys are of great importance in the engineering and mining industries as well as the military and medical applications because of their stability at high temperatures, high strength and dense structures. The present study develops a novel technology for the production of heavy tungsten alloys via thermal treatment of nano-sized metal oxides based on simultaneous reduction and sintering processes. Heavy tungsten alloy (95W-3Ni-2Fe) was produced from the reduction of mixed nano-sized metal oxides precursor in H2 at 1000 o C followed by sintering at 1350–1450 o C for 30–90 min. The reduced and sintered samples were characterized by XRD to follow up the crystallinity, total porosity measurement was used to find out the densification properties, the grain structure and morphology were examined by RLM and SEM attached with EDAX. Micro-hardness tester was also used to investigate the influence of sintering conditions on the grain densification. A fundamental study on the kinetics of reduction of mixed nano-sized metal oxides precursor was performed by isothermal and non-isothermal techniques. Both results from isothermal and non-isothermal tests were used to calculate the activation energy which was correlated with macro- and micro-structures to predict the corresponding reduction mechanism. However, the influence of sintering temperature and time on the crystallinity of the produced phases, grain structure, morphology, total porosity, pore-size distribution, bulk and apparent densities, and the hardness of sintered compacts was extensively investigated. The results revealed that the presence of NiO and/or Fe2O3 in the mixed metal oxides precursor was very important to ease the reducibility of WO3 as the metallic phases of Ni and/or Fe act as a catalyst for the reduction of WO3. The rate of reduction proceeds faster in the following order: NiO > Fe2O3 > mixed oxide > WO3. In non-isothermal experiments, it was found that the heating rate has a considerable effect on the reduction of precursor, i.e., the lower the heating rate, the higher the degree of reduction. It might be reported that the use of nano-sized metal oxides particles in the fabrication of heavy tungsten alloys greatly affects the main properties of the produced alloy. With the increase in sintering time, larger sizes of dense grains were developed, and the matrix became denser as a result of sintering and re-crystallization effects. The higher the sintering time, the higher the grain densification and the less pores formed in the matrix. On the other hand, with the increase in the sintering temperature, the grain boundaries were well defined in which the grains were composed of tungsten metal and surrounded by inter-metallics. The higher the temperature, the higher the XRD peak intensities of metallic tungsten and intermetallics as a result of sintering and re-crystallization.

Cu-Ni Bimetallic Nanowires with Various Structures Originating from Ni Reduction Kinetics.

Bimetallic nanowires play important roles in the fields of electronics and mechanics. However, their structure types and morphological control methods are limited, especially for systems with low lattice mismatch. Herein, for a Cu-Ni bimetallic system with lattice mismatch ratio less than 2.5%, a novel preparation approach of various Cu-Ni nanowires dominated by Ni(II) reduction kinetics is presented. With the increase of Ni(II) reduction rate, the core-shell Cu@Ni straight nanowires, the asymmetric Cu-Ni nanocurves, and asymmetric Cu-Ni nanocoils can be prepared, respectively. The formation of Cu-Ni nanowires with different structures can be divided into the growth of Cu nanowires and the deposition of Ni. The regulatory effects were revealed by establishing a kinetic model for Ni(II) reduction. For the novel Cu-Ni asymmetrically distributed nanocurves and nanocoils, the formation mechanism was proposed by considering the Cu nanowire bending due to the rearrangement of surface ligand and bending-induced symmetry breaking of Ni(II) reduction.

Electrocatalytic reduction of nitrate to ammonia over activated carbon-supported copper-iron bimetallic catalyst synthesized by hydrothermal co-precipitation method

Ammonia synthesis via electrocatalytic reduction of nitrate is a promising approach for green ammonia production. However, this process limited by multiple reaction pathways and NO3− adsorption over electrocatalyst surface. Herein, copper-iron bimetallic catalysts with different atom ratios of Cu/Fe (Cu/Fe = 10/0, 7/3, 5/5, 3/7 and 0/10) and activated carbon as supporter (CuFeOx/AC) were synthesized through hydrothermal co-precipitation method for catalytic reduction of nitrate. Synergistic effects between the Cu and Fe were observed in the copper-iron bimetallic catalysts and an appropriate atom proportion of Cu/Fe was benefit to accelerate the adsorption and electrocatalytic kinetics of nitrate reduction to *NO2 and *NO2 hydrogenation to·NH3 through electron redistribution. The catalyst of 7Cu3FeOx/AC presented the best catalytic performance in nitrogen electroreduction reaction for ammonia synthesis, with an NH3 yield rate of 2091 μg h−1 mgcat−1 and a faradaic efficiency of 76 % at −0.8 V vs. reversible hydrogen electrode. The 7Cu3FeOx/AC also exhibited excellent cycle ability and long-term durability whose NH3 yield rates maintained as high as 1476 and 2326 μg h−1 mgcat−1 after 9 cycles and 10 h durability measurement, respectively. The nitrate reduction behavior over 7Cu3FeOx/AC proceeded with a series of deoxygenation reactions as follows: NO3− → *NO3 → *NO2 → *NO → *NOH → *NH2OH →·NH3. With the above excellent properties, the 7Cu3FeOx/AC may prove to be a promising electrocatalyst for ammonia synthesis via nitrogen electroreduction reaction.

Eco-friendly iron extraction from fe-containing copper smelting slag via reduction roasting with coal and magnetic separation: Experimental and mechanism insights

Copper smelting slag (CSS) is a byproduct produced during the thermal smelting of copper and poses a considerable environmental challenge, particularly in China, where its accumulated volume surpasses 1.8 billion tons. This study utilized the response surface method (RSM) to optimize experimental procedures and reduce costs, the results showed that the effects of each factor on iron recovery were in the following order: roasting temperature > roasting time > coke dosage. The optimized iron recovery of iron extraction from CSS by Magnetization-roasting reached 78.87 %, while the actual iron recovery was 78.84 %. The relative error is very small, indicating that the model is effective. Conducted the thermodynamic computational analysis to understand the migration of metal phases in CSS, employed XPS analysis to identify valence changes in key elements, and the clever combination of restricted reduction kinetics and SEM-EDS analysis shows that the reduction reaction of CSS is mainly controlled by interfacial chemistry and carbon gasification at low temperatures. By processing CSS, the study successfully produced environmentally friendly iron that can be recycled, offering a sustainable solution for managing toxic waste from copper production.

Rationalizing the catalytic surface area of oxygen vacancy‐enriched layered perovskite LaSrCrO4 nanowires on oxygen electrocatalyst for enhanced performance of Li–O2 batteries

AbstractEfficient electrocatalysis at the cathode is crucial to addressing the limited stability and low rate capability of Li−O2 batteries. This study examines the kinetic behavior of Li−O2 batteries utilizing layered perovskite LaSrCrO4 nanowires (NWs) composed of lower oxidation states. Layered perovskite LaSrCrO4 NWs exhibited improved rate capability over a wide range of current densities and longer cycle life in Li−O2 batteries than V‐based layered perovskite (LaSrVO4) and simple perovskite (La0.8Sr0.2CrO3) NWs. X‐ray photoelectron spectroscopy and electrochemical surface area analyses showed that the observed performance variations primarily stemmed from active sites such as oxygen vacancies. In situ Raman analysis showed that these active sites significantly modulate the kinetics of oxygen reduction and evolution, which are related to LiO2 intermediate adsorption. Electrochemical impedance spectroscopy showed that the active sites in layered perovskite LaSrCrO4 NWs contributed to their high charge transfer capability and reduced polarization. This study presents an appealing method for the precise fabrication and analysis of Cr‐based layered perovskites, aimed at achieving highly efficient and stable bifunctional oxygen electrocatalysis.

Tungsten's Role in Enhancing Sintering Resistance of Fe‐W Hierarchical Foams during Redox Cycling

AbstractDirectional freeze‐cast Fe‐W lamellar foams with 10–33 at.% W show distinct microstructural evolutions during steam/hydrogen redox cycling between oxidized and reduced states at 800 ⁰C, depending on W concentration. The Fe‐18 W and Fe‐25 W foams exhibit a sufficient volume fraction of W‐rich phases – λ‐Fe2W to inhibit sintering for α‐Fe in the reduced state and FeWO4 to inhibit sintering for Fe3O4 in the oxidized state – thus forming ligaments comprising two phases (Fe/λ‐Fe2W and Fe3O4/FeWO4, respectively). In contrast, a Fe‐10 W foam with a lower volume fraction of W‐containing phases (λ‐Fe2W and FeWO4) shows lamellae densification as well as core‐shell structure formation, due to Fe outward diffusion during oxidation. While higher W concentration enhances the stability of lamellar structure in Fe‐W foams, degradation still occurs, via buckling of lamellae and swelling of foams after extensive cycling. In situ XRD characterization shows that W addition has a minor effect on the oxidation process but slows reduction due to the sluggish kinetics of FeWO4 reduction. This influence is mitigated by the formation of nanocrystalline W‐rich phases due to the chemical vapor transport (CVT) mechanism during the reduction of FeWO4 to boost the reaction kinetics during redox cycling.

Magnetic Silver Nanoparticles Stabilized by Superhydrophilic Polymer Brushes with Exceptional Kinetics and Catalysis.

Stimuli-responsive catalysts with exceptional kinetics and complete recoverability for efficient recyclability are essential in, for example, converting pollutants and hazardous organic compounds into less harmful chemicals. Here, we used a novel approach to stabilize silver nanoparticles (NPs) through magneto/hydro-responsive anionic polymer brushes that consist of poly (acrylic acid) (PAA) moieties at the amine functional groups of chitosan. Two types of responsive catalyst systems with variable silver loading (wt.%) of high and low (PAAgCHI/Fe3O4/Ag (H, L)) were prepared. The catalytic activity was evaluated by monitoring the reduction of organic dye compounds, 4-nitrophenol and methyl orange in the presence of NaBH4. The high dispersity and hydrophilic nature of the catalyst provided exceptional kinetics for dye reduction that surpassed previously reported nanocatalysts for organic dye reduction. Dynamic light scattering (DLS) measurements were carried out to study the colloidal stability of the nanocatalysts. The hybrid materials not only showed enhanced colloidal stability due to electrostatic repulsion among adjacent polymer brushes but also offered more rapid kinetics when compared with as-prepared Ag nanoparticles (AgNPs), which results from super-hydrophilicity and easy accumulation/diffusion of dye species within polymer brushes. Such remarkable kinetics, biodegradability, biocompatibility, low cost and facile magnetic recoverability of the Ag nanocatalysts reported here contribute to their ranking among the top catalyst systems reported in the literature. It was observed that the apparent catalytic rate constant for the reduction of methyl orange dye was enhanced, PAAgCHI/Fe3O4/Ag (H) ca. 35-fold and PAAgCHI/Fe3O4/Ag (L) ca. 23-fold, when compared against the as prepared AgNPs. Finally, the regeneration and recyclability of the nanocatalyst systems were studied over 15 consecutive cycles. It was demonstrated that the nanomaterials display excellent recyclability without a notable loss in catalytic activity.

A novel Co-free and efficient Pr0.5Ba0.5Fe0.8Cu0.2O3-δ nanofiber cathode material for intermediate temperature solid oxide fuel cells

Fe-based perovskite without Co has a low thermal expansion coefficient and can be used as a solid oxide fuel cell (SOFC) cathode to ensure the thermal compatibility with the electrolyte; however, its further advancement is impeded by sluggish oxygen reduction reaction (ORR) dynamics. In this work, the electrospinning method and Cu doping strategy are employed to improve the microstructure and oxygen reduction kinetics of Pr0.5Ba0.5FeO3-δ cathodes. The results show that Pr0.5Ba0.5Fe0.8Cu0.2O3-δ has a unique fiber structure and high specific surface area, and the introduction of Cu facilitates the release of lattice oxygen, effectively increasing the oxygen vacancy content. The relaxation time distribution analysis and oxygen reduction reaction dynamics indicate that the oxygen adsorption-dissociation process is the main rate-limiting step in the oxygen reduction reaction of Pr0.5Ba0.5Fe0.8Cu0.2O3-δ electrode materials. At 700 °C, the area-specific resistance (ASR) of the symmetric cell of Pr0.5Ba0.5Fe0.8Cu0.2O3-δ fiber material is 0.071 Ω cm2, and the power density of the single cell reaches 988 mW cm−2, which shows good electrochemical output performance and long-term operational stability. The preparation of nanofiber cathodes with high specific surface area and porosity by electrospinning provides an effective strategy to enhance the electrocatalytic activity of the IT-SOFC cathode.

Fluid-Induced Piezoelectric Field Enhancing Photo-Assisted Zn-Air Batteries Based on a Fe@P(V-T) Microhelical Cathode.

Photo-assisted Zn-air batteries can accelerate the kinetics of oxygen reduction and oxygen evolution reactions (ORR/OER); however, challenges such as rapid charge carrier recombination and continuous electrolyte evaporation remain. Herein, for the first time, piezoelectric catalysis is introduced in a photo-assisted Zn-air battery to improve carrier separation capability and accelerate the ORR/OER kinetics of the photoelectric cathode. The designed microhelical catalyst exploits simple harmonic vibrations to regenerate the built-in electric field continuously. Specifically, in the presence of the low-frequency kinetic energy that occurs during water flow, the piezoelectric-photocoupling catalyst of poly(vinylidene fluoride-co-trifluoroethylene)@ferric oxide(Fe@P(V-T)) is periodically deformed, generating a constant reconfiguration of the built-in electric field that separates photogenerated electrons and holes continuously. Further, on exposure to microvibrations, the gap between the charge and discharge potentials of the Fe@P(V-T)-based photo-assisted Zn-air battery is reduced by 1.7 times compared to that without piezoelectric assistance, indicating that piezoelectric catalysis is highly effective for enhancing photocatalytic efficiency. This study provides a thorough understanding of coupling piezoelectric polarization and photo-assisted strategy in the field of energy storage and opens a fresh perspective for the investigation of multi-field coupling-assisted Zn-air batteries.

Non-metal doping enhsances oxygen reduction kinetics and CO2 tolerance of SrFeO3-δ perovskite as high-performance cathodes for solid oxide fuel cells

The sluggish of the oxygen reduction reaction (ORR) kinetics and the susceptibility to CO2 interactions are major barriers to the widespread application of solid oxide fuel cells (SOFCs). In this study, a non-metal cation doping strategy was employed to enhance the ORR catalytic activity and CO2 tolerance of SrFeO3-δ cathode. SrFe1-xPxO3-δ (SFPx, x = 0, 0.05, 0.1, 0.15, 0.2) materials were synthesized by substituting phosphorus (P) for Fe in SrFeO3-δ. The doping of P facilitated the formation of oxygen vacancies in SrFeO3-δ, enhancing oxygen adsorption, dissociation, diffusion, and charge transfer processes, leading to a notable increase in ORR catalytic activity. At 800 ℃, the polarization resistance of SFP0.15 was 0.08 Ω cm2, a reduction of 42.86 % compared to undoped SrFeO3-δ. Additionally, SFP0.15 achieved a peak power density of 749.36 mW cm2, representing a 91.99 % enhancement over SrFeO3-δ. These findings suggest that non-metal cation doping is an effective approach to boost the performance of SrFeO3-δ perovskite cathode.

Accelerated oxygen reduction kinetics in BaCo0.4Fe0.4Zr0.2O3-δ cathode via doping with a trace amount of tungsten for protonic ceramic fuel cells

Protonic ceramic fuel cells (PCFCs), which are based on proton conducting electrolytes, are a class of power generation devices that can efficiently operate at the intermediate (500–700 °C), even low (450 °C) temperatures, but their development is hindered by sluggish cathodic kinetics at reduced temperatures. At the PCFC cathode, the absorbed oxygen molecules react with oxygen vacancies, protons and electrons to generate water and release electrical energy. Thus, the PCFC cathode materials require percolation network for proton, oxide-ion, and electron carriers simultaneously. In this work, we developed a triple ionic-electronic conductor BaCo0.4Fe0.4Zr0.15W0.05O3-δ as a new cathode material for the PCFCs using BaZr0.1Ce0.7Y0.1Yb0.1O3-δ as the electrolyte. Anode supported cells were fabricated and the performances were investigated. Compared with the parent oxide, tungsten doping can significantly improve the electrochemical reduction kinetic of oxygen. The BaCo0.4Fe0.4Zr0.15W0.05O3-δ based PCFC obtained the peak power density of 688 mW ⋅ cm−2 at 600 °C, which is 1.29 time higher than that of BaCo0.4Fe0.4Zr0.2O3-δ based PCFC (the peak power density of 534 mW ⋅ cm−2 at 600 °C). Moreover, BaCo0.4Fe0.4Zr0.15W0.05O3-δ has a better thermal expansion matching with the electrolyte material BaZr0.1Ce0.7Y0.1Yb0.1O3-δ.

Hydrogen technologies for decarbonization of ferrous metallurgy: scientific background and technical capabilities

To date, the use of ferrous hydrogen in metallurgy is considered from several positions. First, the partial or complete replacement of carbon with hydrogen reduces greenhouse gas emissions of CO2. Secondly, due to the different chemical affinity for oxygen, it becomes possible to selectively (selectively) extract components from complex complex ores and man-made materials. Thirdly, the absence of carbon in the reaction zone will make it possible to obtain a metal with a low content of carbides, which in many cases increases the demand for the product. Thermodynamic calculations of a multicomponent oxide system (Ni, Fe, P, Zn, Mn, V, Cr, O) in the presence of various reducing agents: carbon, hydrogen are performed using the TERRA software package, and their combined effects are considered. It is shown that the type of reducing agent affects the temperature of the beginning of the reduction of metals and the degree of their metallization. Thus, by selecting the type of reducing agent, its quantity, and the temperature of the process, it is possible to selectively extract some metals, and leave others in an oxidized state. Ilmenite concentrate in the form of a briquette was used in laboratory tests. The analysis of the iron reduction process using carbon or hydrogen as a reducing agent has been carried out. In comparison with the results obtained using carbon, the kinetics of iron reduction with hydrogen is higher. At the same time, the reduction proceeds with the formation of metallic iron, rutile (TiO2) and residual ilmenite. Whereas, in a carbothermic process occurring at higher temperatures (1000–1300 ℃), the reduction products are iron and iron ditanate (FeTi2O5). In addition, an important advantage of selective reduction by gas is the possibility of subsequent separation of the metallic and oxide phases by melting, without fear of secondary reduction due to solid carbon residues.

Boosting the performance of La0.5Sr0.5Fe0.9Mo0.1O3-δ oxygen electrode via surface-decoration with Pr6O11 nano-catalysts

Cobalt-free La0.5Sr0.5Fe0.9Mo0.1O3-δ (LSFM) oxide is particularly investigated as a durable and efficient oxygen electrode material for the reversible solid oxide cells (RSOCs) in this study. Pr6O11 nano-catalysts are introduced into LSFM oxygen electrode as synergistic catalysts to enhance and optimize the electrode reactions. Results demonstrate an effectively promoted oxygen reduction and evolution reaction kinetics of the Pr6O11 decorated LSFM electrode. Polarization resistances (Rp) of LSFM electrode are dramatically reduced with the increasing Pr6O11 nano-catalysts and the lowest Rp of 0.039 Ω cm2 is obtained at 800 °C, which is ∼97% lower than that of the LSFM electrode. The Pr6O11 decorated LSFM oxygen electrode also displays a superior durability under cyclic anodic and cathodic polarizations. Furthermore, both the maximum power density and electrolytic current density of the Pr6O11 decorated cell are more than 2 times that of the LSFM cell. Results make clear reliability of the Pr6O11 decorated LSFM to be a promising oxygen electrode for RSOCs.

2-Propyl-1H-imidazole-4,5-dicarboxylate acid supported cu/ni/fe/co complexes: synthesis, biological and catalytic evaluation

Herein, we report 2-propyl-1H-imidazole-4,5-dicarboxylate complexes of Cu/Co/Fe/Ni metal ions. The complexes have been characterized using powder X-ray diffraction, FTIR, and mass spectrometry. Thermal gravimetric analysis (TGA) established their thermal stability, enduring temperatures of up to 650 °C. The interaction of Bovine Serum Albumin (BSA) and DNA with these complexes was examined, revealing a significant binding affinity up to 70%. Fluorescence quenching experiments also showed the binding of complexes with biomolecules. These interactions were substantiated by molecular docking studies against the proteins 3v03 (BSA) and 1d28 (DNA), shedding light on the essential interactions driving their potential medicinal activity. The Cu complex displayed a notably high GSC score and a substantial area as determined through the Patch Dock server. Free radical interaction with 2,2-diphenylpicrylhydrazyl (DPPH) shows their antioxidant activity where Cu and Fe complexes expressed greater activity as compared to others. The catalytic properties of the compounds were assessed using p-nitrophenol (PNP) where the complexes exhibited reducing activity, leading to a conversion of over 90% of PNP into p-aminophenol. Analysis revealed a pseudo-second-order model closely aligned with experimental values, indicating second-order reduction kinetics.

Engineering ZnIn2S4 with efficient charge separation and utilization for synergistic accelerate dual-function photocatalysis

Combining photocatalytic reduction with organic synthetic oxidation in the same photocatalytic redox system can effectively utilize photoexcited electrons and holes from solar to chemical energy. Here, we stabilized 0D Au clusters on the substrate surface of Zn vacancies modified 2D ZnIn2S4 (ZIS-V) nanosheets by chemically bonding Au-S interaction, forming surfactant functionalized Au/ZIS-V photocatalyst, which can not only synergistic accelerate the selective oxidation of phenylcarbinol to value-added products coupled with clean energy hydrogen production but also further drive photocatalytic CO2-to-CO conversion. An internal electric field of Au/ZIS-V ohmic junction and Zn vacancies synchronously promote the photoexcited charge carrier separation and transfer to optimized active sites for redox reactions. Compared with CO2 reduction in water and the pristine ZnIn2S4, the reaction thermodynamics and kinetics of CO2 reduction over the Au/ZIS-V were simultaneously improved about 11.09 and 45.51 times, respectively. Moreover, the photocatalytic redox mechanisms were also profoundly studied by 13CO2 isotope tracing tests, in situ electron paramagnetic resonance (in situ EPR), in situ X-ray photoelectron spectroscopy (in situ XPS), in situ diffuse reflection infrared Fourier transform spectroscopy (in situ DRIFTS) and density functional theory (DFT) characterizations, etc. These results demonstrate the advantages of vacancies coupled with metal clusters in the synergetic enhancement of photocatalytic redox performance and have great potential applications in a wide range of environments and energy.

Isothermal reduction kinetics and reduction prediction for iron ore pellets

Isothermal reduction kinetics and reduction prediction for iron ore pellets

Constitutive Model and Experimental Verification of Kinetics of Non-isothermal Hydrogen Reduction of Ilmenite: A Case Study on Kahnuj Ilmenite

Constitutive Model and Experimental Verification of Kinetics of Non-isothermal Hydrogen Reduction of Ilmenite: A Case Study on Kahnuj Ilmenite

The screening of iron oxides for long-term transformation into vivianite to recover phosphorus from sewage

The reducibility of iron oxides, depending on their properties, influences the kinetics of dissimilatory iron reduction (DIR) during vivianite recovery in sewage. This study elucidated the correlation between properties of iron oxides and kinetics of DIR during the long-term transformation into vivianite, mediated by Geobacter sulfurreducens PCA and sewage. The positive correlation between surface reactivity of iron oxides and reduction rate constant (k) influenced the terminal vivianite recovery efficiency. Akaganeite with the highest adhesion work and surface energy required the lowest reduction energy (Ea), obtained the highest k of 1.36 × 10–2 day-1 and vivianite recovery efficiency of 43 %. The vivianite yield with akaganeite as iron source was 76–164 % higher than goethite, hematite, feroxyhyte, and ferrihydrite in sewage. The distribution of P with akaganeite during DIR in sewage further suggested a more efficient pathway of direct vivianite formation via bio-reduced Fe(II) rather than indirect reduction of ferric phosphate precipitates. Thus, akaganeite was screened out as superior iron source among various iron oxides for vivianite recovery, which provided insights into the fate of iron sources and the cycle of P in sewage.