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Phenylhydroxylamine and its derivates (PHAs) are important chemical intermediates. Phenylhydroxylamines are mainly produced via the catalytic reduction of aromatic nitro compounds. However, this catalytic reduction method prefers to generate thermodynamically stable aromatic amine. Thus, designing suitable catalytic systems, especially catalysts to selectively convert aromatic nitro compounds to PHAs, has received increasing attention but remains challenging. In this review, we initially provide a brief overview of the various strategies employed for the synthesis of PHAs, focusing on reducing aromatic nitro compounds. Subsequently, an in-depth analysis is presented on the catalytic reduction process, encompassing discussions on catalysts, reductants, hydrogen sources, and a comprehensive assessment of the merits and drawbacks of various catalytic systems. Furthermore, a concise overview is provided regarding the progress made in comprehending the mechanisms involved in this process of catalytic reduction of aromatic nitro compounds. Finally, the main challenges and prospects in PHAs' production via catalytic reduction are outlined. [ABSTRACT FROM AUTHOR]

As a heavy metal element with great harm and heavy pollution in soil pollution, chromium (Cr) has posed a great threat to the soil environment and human living environment. Chromium mainly exists in the form of Cr(III) and Cr(VI) in the soil. It is of great significance to reduce Cr(VI) with strong toxicity and easy migration to Cr(III) with low toxicity and low migration. There are a large number of active groups in soil humus, which have a strong affinity with heavy metal ions and play an important role in the reduction of chromium. Humic substances are classified into three categories; however, fewer studies have been carried out simultaneously to investigate the functional groups involved in the reactions of humic acid (HA), fulvic acid (FA), and humic matter (HM) with Cr. In the present study, HA, FA, and HM were used to interact with Cr to investigate the mechanism of humus reduction of Cr(VI). The results showed the reducing ability of humic substances: HA > FA > HM. The functional groups that play a reducing role in humic substances are mainly carboxyl groups, ester groups, phenolic hydroxyl groups, and polysaccharides. The C=O and C—O bonds play a major role in the reduction of humus, but not all C=O and C—O bonds have changed during the reaction. The adsorption–reduction process was mainly carried out on the surface of humic substances, and Cr(III) was mainly adsorbed on humic substances with trace amounts of Cr(VI).7 [ABSTRACT FROM AUTHOR]

The aim of this research was to design and simulate a low-cost, easy-to-maintain molten aluminum alloy casting mechanism. This mechanism was intended to address labor shortages in harsh and high-temperature environments. The functional requirements of the mechanism were as follows: it needed to withstand temperatures exceeding 700 ℃, operate without deformation, and ensure that the ladle’s positioning error during each rotation did not exceed 1 deg. Additionally, the mechanism’s durability had to meet industry standards, with the ladle’s output shaft capable of bearing pressures exceeding 100 kg/cm2. The design should be modular, allowing for the replacement of specific components to accommodate varying specifications in the future. To begin with, a 3D model was constructed using SolidWorks CAD software to verify operational interferences and simulate assembly, ensuring that the design was practical and logically sound. During the design process, mechanical design handbooks and catalogs from major component suppliers were consulted to utilize standard sizes and specifications as much as possible. Once the model was confirmed, structural analyses were conducted using Ansys to ensure that the mechanism could withstand significant loads without failure. Furthermore, the design would focus on ensuring that the mechanism was robust and reliable under hightemperature conditions, reducing the need for frequent maintenance and downtime. The modular design approach not only enhances the flexibility of the mechanism but also simplifies future upgrades and adjustments, ensuring long-term usability and adaptability. [ABSTRACT FROM AUTHOR]

The abilities of Ni-Si52, Ni-SiNT(6, 0), Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) as catalyst of CO2-RR to CH4 are compared. The Eadoption and Eformation of Ni-Si52, Ni-SiNT(6, 0), Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) are stable parameters. The Eadoption of CO2-RR on Ni-Si52, Ni-SiNT(6, 0), Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) are − 3.34, -3.47, -5.42, -3.81, -3.99 and − 5.89 eV. The HCOOH, CO, HCOH, CH3OH and CH4 adsorption as important products for CO2-RR on Ni doped nanotubes an nanocages are examined. The Eformation of CO2-RR on Ni-Si52, Ni-SiNT(6, 0), Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) are − 4.27, -4.39, -4.51, -4.87, -5.02 and − 4.92 eV. The CO2-RR mechanisms on Ni doped nanotubes and nanocages are examined. The overpotential of CO2-RR on Ni-Si52, Ni-SiNT(6, 0), Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) are 0.338, 0.327, 0.331, 0.304, 0.295 and 0.296 V. The Overpotential of CO2-RR on Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) are lower than metal catalysts. The Ni-Si52, Ni-SiNT(6, 0), Ni-C52, Ni-B26N26, Ni-CNT (6, 0) and Ni-BNNT (6, 0) is processed the CO2-RR. [ABSTRACT FROM AUTHOR]

E. coli nitroreductase A (NfsA) is a candidate for gene-directed prodrug cancer therapy using bioreductively activated nitroaromatic compounds (ArNO2). In this work, we determined the standard redox potential of FMN of NfsA to be −215 ± 5 mV at pH 7.0. FMN semiquinone was not formed during 5-deazaflavin-sensitized NfsA photoreduction. This determines the two-electron character of the reduction of ArNO2 and quinones (Q). In parallel, we characterized the oxidant specificity of NfsA with an emphasis on its structure. Except for negative outliers nitracrine and SN-36506, the reactivity of ArNO2 increases with their electron affinity (single-electron reduction potential, E17) and is unaffected by their lipophilicity and Van der Waals volume up to 386 Å. The reactivity of quinoidal oxidants is not clearly dependent on E17, but 2-hydroxy-1,4-naphthoquinones were identified as positive outliers and a number of compounds with diverse structures as negative outliers. 2-Hydroxy-1,4-naphthoquinones are characterized by the most positive reaction activation entropy and the negative outlier tetramethyl-1,4-benzoquinone by the most negative. Computer modelling data showed that the formation of H bonds with Arg15, Arg133, and Ser40, plays a major role in the binding of oxidants to reduced NfsA, while the role of the π–π interaction of their aromatic structures is less significant. Typically, the calculated hydride-transfer distances during ArNO2 reduction are smallwer than for Q. This explains the lower reactivity of quinones. Another factor that slows down the reduction is the presence of positively charged aliphatic substituents. [ABSTRACT FROM AUTHOR]

Transition metal iron and persistent free radicals (PFRs) both affect the redox properties of biochar, but the electron transfer relationship between them and the coupling reduction mechanism of Cr(VI) requires further investigation. To untangle the interplay between iron and PFRs in biochar and the influences on redox properties, FeCl 3 -modified rice husk biochar (FBCs) was prepared and its reduction mechanism for Cr(VI) without light was evaluated. The FBCs had higher surface positive charges, oxygen-containing functional groups, and PFRs compared with pristine rice husk biochar (BC). Phenoxyl PFRs with high electron-donating capability formed in biochar. The pronounced electron paramagnetic resonance signals showed that the PFRs preferred to form at lower Fe(III) concentrations. While a high concentration of Fe(III) would be reduced to Fe(II) and consumed the formed PFRs. Adsorption kinetics and X-ray photoelectron spectroscopy analysis indicated that the FBCs effectively enhanced the Cr(VI) removal efficiency by 1.54-8.20 fold and the Cr(VI) reduction efficiency by 1.88-9.29 fold compared to those of BC. PFRs quenching and competitive reductant addition experiments revealed that the higher Cr(VI) reduction performance of FBCs was mainly attributed to the formed PFRs, which could contribute to ∼74.0% of Cr(VI) reduction by direct or indirect electron transfer. The PFRs on FBCs surfaces could promote the Fe(III)/Fe(II) cycle through single electron transfer and synergistically accelerate ∼52.3% of Cr(VI) reduction. This study provides an improved understanding of the reduction mechanism of iron-modified biochar PFRs on Cr(VI) in environments. [Display omitted] [ABSTRACT FROM AUTHOR]

Electric arc furnace dust (EAFD) is a hazardous by-product of steel production. As global steel output increases, substantial amounts of EAFD are produced, which causes significant environmental issues. EAFD contains quantities of Fe and Zn, which could be reused as raw materials in the steelmaking process. However, zinc oxides can be reduced and vaporized during this process, forming zinc vapor that contaminates equipment surfaces and causes damage. Consequently, various pyrometallurgical methods have been proposed for zinc removal from EAFD. Due to the extensive usage of carbonaceous materials, these methods contribute to significant CO2, raising concerns about greenhouse gas emissions. Microwave heating offers an efficient, energy-saving, and environmentally friendly alternative to pyrometallurgical approaches. EAFD can generate heat under microwave irradiation without carbon addition, which means the CO2 emissions can be reduced by replacing the reductant in the microwave heating process. Furthermore, microwaves enhance zinc removal reactions to a certain extent, resulting in higher efficiency. Thus, employing microwave heating for EAFD processing has significant potential for future development. This paper reviews recent research on using microwave heating for zinc removal from EAFD, focusing on the heating behavior of EAFD in microwaves and the mechanisms of zinc removal. This review will be crucial for researchers working on processing EAFD using microwave heating and could help guide the development of more sustainable and efficient methods. [ABSTRACT FROM AUTHOR]

Acetic acid (AC) is a major by-product from fermentation processes for producing succinic acid (SA) using Actinobacillus succinogenes. Previous experiments have demonstrated that sodium bisulfate (NaHSO3) can significantly decrease AC production by A. succinogenes GXAS137 during SA fermentation. However, the mechanism of AC reduction is poorly understood. In this study, the transcriptional profiles of the strain were compared through Illumina RNA-seq to identify differentially expressed genes (DEGs). A total of 210 DEGs were identified by expression analysis: 83 and 127 genes up-regulated and down-regulated, respectively, in response to NaHSO3 treatment. The functional annotation analysis of DEGs showed that the genes were mainly involved in carbohydrates, inorganic ions, amino acid transport, metabolism, and energy production and conversion. The mechanisms of AC reduction might be related to two aspects: (i) the lipoic acid synthesis pathway (LipA, LipB) was significantly down-regulated, which blocked the pathway catalyzed by pyruvate dehydrogenase complex to synthesize acetyl-coenzyme A (acetyl-CoA) from pyruvate; (ii) the expression level of the gene encoding bifunctional acetaldehyde-alcohol dehydrogenase was significantly up-regulated, and this effect facilitated the synthesis of ethanol from acetyl-CoA. However, the reaction of NaHSO3 with the intermediate metabolite acetaldehyde blocked the production of ethanol and consumed acetyl-CoA, thereby decreasing AC production. Thus, our study provides new insights into the molecular mechanism of AC decreased underlying the treatment of NaHSO3 and will deepen the understanding of the complex regulatory mechanisms of A. succinogenes.

Phenylhydroxylamine and its derivates (PHAs) are important chemical intermediates. Phenylhydroxylamines are mainly produced via the catalytic reduction of aromatic nitro compounds. However, this catalytic reduction method prefers to generate thermodynamically stable aromatic amine. Thus, designing suitable catalytic systems, especially catalysts to selectively convert aromatic nitro compounds to PHAs, has received increasing attention but remains challenging. In this review, we initially provide a brief overview of the various strategies employed for the synthesis of PHAs, focusing on reducing aromatic nitro compounds. Subsequently, an in-depth analysis is presented on the catalytic reduction process, encompassing discussions on catalysts, reductants, hydrogen sources, and a comprehensive assessment of the merits and drawbacks of various catalytic systems. Furthermore, a concise overview is provided regarding the progress made in comprehending the mechanisms involved in this process of catalytic reduction of aromatic nitro compounds. Finally, the main challenges and prospects in PHAs’ production via catalytic reduction are outlined.

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The electrochemical reduction mechanism of nitrosobenzene in acetonitrile was reconsidered in this work. The commonly accepted mechanism assumes that the nitrosobenzene radical anion dimerize to yield a dianion, which decompose into azoxybenzene as the reduction product. Even though this proposal is consistent with preparative experiments, it does not reproduce fully the experimental voltammetric behaviour when it is simulated. Also, It does not explain why the apparent electron number is different in the time scale of cyclic voltammetry and preparative electrolysis. To understand these discrepancies, it was proposed the intervention of reactions consuming part of the starting nitrosobenzene, which allowed to reconsider the role of alternative chemical reactions like that occurring between the anion of phenylhydroxylamine with nitrosobenzene and the hydroxyl ion with nitrosobenzene. In this framework, these concomitant reactions were additionally included in the mechanism to simulate the voltammetric behaviour at different scan rates. Thermodynamic and kinetic parameters of the extended mechanism are reported. Since in the hydroxyl ion is either product or reactive in some reaction steps, the global mechanism was deemed to occurs as a kind of loop. [ABSTRACT FROM AUTHOR]

Acetic acid (AC) is a major by-product from fermentation processes for producing succinic acid (SA) using Actinobacillus succinogenes. Previous experiments have demonstrated that sodium bisulfate (NaHSO3) can significantly decrease AC production by A. succinogenes GXAS137 during SA fermentation. However, the mechanism of AC reduction is poorly understood. In this study, the transcriptional profiles of the strain were compared through Illumina RNA-seq to identify differentially expressed genes (DEGs). A total of 210 DEGs were identified by expression analysis: 83 and 127 genes up-regulated and down-regulated, respectively, in response to NaHSO3 treatment. The functional annotation analysis of DEGs showed that the genes were mainly involved in carbohydrates, inorganic ions, amino acid transport, metabolism, and energy production and conversion. The mechanisms of AC reduction might be related to two aspects: (i) the lipoic acid synthesis pathway (LipA, LipB) was significantly down-regulated, which blocked the pathway catalyzed by pyruvate dehydrogenase complex to synthesize acetyl-coenzyme A (acetyl-CoA) from pyruvate; (ii) the expression level of the gene encoding bifunctional acetaldehyde-alcohol dehydrogenase was significantly up-regulated, and this effect facilitated the synthesis of ethanol from acetyl-CoA. However, the reaction of NaHSO3 with the intermediate metabolite acetaldehyde blocked the production of ethanol and consumed acetyl-CoA, thereby decreasing AC production. Thus, our study provides new insights into the molecular mechanism of AC decreased underlying the treatment of NaHSO3 and will deepen the understanding of the complex regulatory mechanisms of A. succinogenes. [ABSTRACT FROM AUTHOR]

The use of silver nanoparticles (AgNPs) in many consumer products is expected to increase in the future due to their multifaceted properties. With the increasing demand for AgNPs, manufacturers are focusing more on exploring various methods for synthesizing AgNPs that are safer, cost-effective, and scalable. Synthesis of AgNPs using biological processes is advantageous over physical and chemical methods, primarily due to low cost and being free of hazardous chemical reagents. Among the biological processes, various groups of algae have been explored for the synthesis of AgNPs. Different biogenic substances present in the algae serve as excellent reducing and capping agents for the synthesis of NPs. Moreover, in comparison to plants and other microorganisms, algae are easy to maintain and show mass multiplication. In this review, state-of-the-art information has been collected regarding the usage of different groups of algae for the synthesis of AgNPs, their physico-chemical properties, mechanism of synthesis, and bioactivity in detail. One of the applications of AgNPs i.e., antimicrobial activity, is discussed in detail. Further, a conceptual framework regarding various techniques used for characterization of nanoparticles is described. [ABSTRACT FROM AUTHOR]

The use of a contralateral cane has demonstrated a reduction in the external knee adduction moment (KAM) in patients with knee osteoarthritis. However, the underlying mechanism remains unclear. This study aimed to investigate the specific mechanism in healthy young subjects. Sixteen healthy young participants were included in this study. They walked on a floor under three loading conditions: no cane and with cane loads equivalent to 5% and 10% of body weight. Change in posture and kinetic features of ipsilateral leg were examined at two instants of ground reaction force (GRF) peaks. The results revealed a substantial decrease (40–55%) in both KAM and moment arm, whereas only 12% decrease was observed in GRF with 10% cane loading. Furthermore, KAM was strongly correlated with moment arm (r = 0.97, p < 0.01), but not with GRF (p > 0.05). The reduction in moment arm could be attributed to a medial shift of knee joint and/or a lateral shift of GRF. At the maximum cane loading, medial shift in the knee joint center was significant (p < 0.001), while any shift in GRF was insignificant (p > 0.80). The results suggest that the primary factor contributing to the reduction in KAM is the decrease in moment arm among healthy young subjects. Importantly, the reduction in moment arm was primarily induced by a medial shift of the knee joint center, emphasizing the significance of postural changes. [ABSTRACT FROM AUTHOR]

Abstract The electrochemical reduction mechanism of nitrosobenzene in acetonitrile was reconsidered in this work. The commonly accepted mechanism assumes that the nitrosobenzene radical anion dimerize to yield a dianion, which decompose into azoxybenzene as the reduction product. Even though this proposal is consistent with preparative experiments, it does not reproduce fully the experimental voltammetric behaviour when it is simulated. Also, It does not explain why the apparent electron number is different in the time scale of cyclic voltammetry and preparative electrolysis. To understand these discrepancies, it was proposed the intervention of reactions consuming part of the starting nitrosobenzene, which allowed to reconsider the role of alternative chemical reactions like that occurring between the anion of phenylhydroxylamine with nitrosobenzene and the hydroxyl ion with nitrosobenzene. In this framework, these concomitant reactions were additionally included in the mechanism to simulate the voltammetric behaviour at different scan rates. Thermodynamic and kinetic parameters of the extended mechanism are reported. Since in the hydroxyl ion is either product or reactive in some reaction steps, the global mechanism was deemed to occurs as a kind of loop.

E. coli nitroreductase A (NfsA) is a candidate for gene-directed prodrug cancer therapy using bioreductively activated nitroaromatic compounds (ArNO2). In this work, we determined the standard redox potential of FMN of NfsA to be −215 ± 5 mV at pH 7.0. FMN semiquinone was not formed during 5-deazaflavin-sensitized NfsA photoreduction. This determines the two-electron character of the reduction of ArNO2 and quinones (Q). In parallel, we characterized the oxidant specificity of NfsA with an emphasis on its structure. Except for negative outliers nitracrine and SN-36506, the reactivity of ArNO2 increases with their electron affinity (single-electron reduction potential, E17) and is unaffected by their lipophilicity and Van der Waals volume up to 386 Å. The reactivity of quinoidal oxidants is not clearly dependent on E17, but 2-hydroxy-1,4-naphthoquinones were identified as positive outliers and a number of compounds with diverse structures as negative outliers. 2-Hydroxy-1,4-naphthoquinones are characterized by the most positive reaction activation entropy and the negative outlier tetramethyl-1,4-benzoquinone by the most negative. Computer modelling data showed that the formation of H bonds with Arg15, Arg133, and Ser40, plays a major role in the binding of oxidants to reduced NfsA, while the role of the π–π interaction of their aromatic structures is less significant. Typically, the calculated hydride-transfer distances during ArNO2 reduction are smallwer than for Q. This explains the lower reactivity of quinones. Another factor that slows down the reduction is the presence of positively charged aliphatic substituents.

Currently, there is a lack of detailed knowledge about methane (CH4) reactions on metal oxide surfaces. This reaction involves in different processes such as chemical looping combustion and catalytic carbon dioxide (CO2) reforming of CH4. In this study, in situ diffuse reflectance infrared Fourier transform spectroscopy was used to investigate CH4 reaction on three transition metal oxides (CoO, CuO, and α-Fe2O3) which are commonly used in these processes at temperatures ranging from 100 °C to 700 °C. The results show that CH4 is adsorbed on the metal oxide surfaces as methoxy and formate, and then the methoxy group reacts with the metal oxide lattice oxygen forming bicarbonate. Under the effect of the used reaction temperature, the bicarbonate decomposes to CO2 and water vapor. [ABSTRACT FROM AUTHOR]

Green synthesis process has been developed to produce MgO nanoparticles using wet chemical method. In this process, Madhuca longifolia (M. longifolia) flower extracts has been used as a reducing and stabilizing agent and magnesium nitrate hexahydrate is used as a metal precursor. This study exhibits the effect of varied concentrations of metal precursors and flower extracts on the shape and size of the MgO nanoparticles. FTIR, UV vis spectroscopy, SEM, EDS and HRTEM analysis have been carried out to identify the functional groups involved in the reduction process, confirmation of MgO nanoparticles, morphological and elemental analysis of the MgO nanoparticles respectively. The results confirmed the presence of spherical MgO nanoparticles decorated over the surface of MgO microclusters. It is observed that the varying concentration of flower extracts and precursor have a profound effect on morphology of the nanoparticles resulting in the decrease in cluster size with the increase in extract concentration. The nanoparticles were also tested for the presence of antibacterial activity against the bacterial species of Escherichia coli and Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

The optimization of the ironmaking process for the preparation of high-purity metallic iron has become an important part of the production of the iron and steel industry due to the increasing demand for steel in the modern industry. This article adopted the soluble anode molten salt electrolysis process to prepare a soluble anode with excellent conductivity by mixing Fe2O3 and C in a molar ratio of 1:3, sintering at 1073 K for 6 h. The metal iron was electrolytically deposited on the cathode by applying a constant current of 0.1 A for 6 h in the NaCl-CaCl2 molten salt system. The anode dissolution and cathode deposition mechanisms were analyzed based on the electrolysis U-t curve. The experimental results showed that the presence of C after sintering reduces the impedance value by reducing Fe2O3 to Fe3O4. During the electrolysis process, Fe2+ in Fe3O4 oxidized to Fe3+ and entered the molten salt, migrated to the vicinity of the cathode, and underwent the reduction process of Fe3+-Fe2+-Fe during the cathodic reduction process. The deposited Fe on the cathode exhibited a dendritic crystal structure with a purity of 99.51%.

In this study, the complexity of sodium ascorbate as a reducing reagent for copper by executing reactions with different ascorbate concentrations at 30°C and a copper concentration at 5 mM was emphasized. It was found that increasing the molar ratio of nascorbate/nCu2+ from 1:1 to 10:1 prolonged the time for the completion of the reduction from 30 to 300 min, respectively. The reactions were investigated by the cyclic voltammetry method and the products were characterized by scanning electron microscopy and X-ray diffraction analyses. The synthesized materials obtained with molar ratios of 1:1 and 10:1 were composed of 55.47% Cu + 44.53% Cu2 O (labeled as As1) and 73.66% Cu + 26.34% Cu2 O (labeled as As10), respectively. Both products were tested for their ability to discolor Basic Red 29 via the Fenton reaction. The discoloration of the dye was more rapid with As1, due to the higher Cu2 O content. [ABSTRACT FROM AUTHOR]

CeO2 and CeO2‐based materials are widely used as catalysts and catalyst supports for a variety of chemical reactions. The ability to form oxygen vacancies plays an important role in the catalytic activities in these materials. Therefore, revealing the reduction mechanism for CeO2 is crucial to understanding the catalytic activities. In this study, shape‐controlled CeO2 nanoparticles are fabricated and the distribution of surface oxygen vacancies on the (100) and (111) surfaces is systematically studied using scanning transmission electron microscopy and electron energy‐loss spectroscopy and the response to H2 reduction treatment. It is successfully demonstrated that both catalytic activities and the ability to form oxygen vacancies are strongly dependent on the type of lattice planes. Moreover, the present results provide important insights into the reduction mechanism for CeO2, in which bulk oxygen instead of the widely believed surface capping oxygen makes no small contribution to the initial reduction step. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of chloral hydrate in aqueous solutions at various pH values was investigated by using polarography. Reduction of chloral hydrate takes place in two steps: one appears as a small limiting current value that corresponds to the reduction of the unhydrated form, present in solutions in less than 3%, and another larger limiting current value at more negative potentials corresponding to a reduction of C‐Cl bonds in the hydrated form. Reduction schemes for both the hydrated and unhydrated forms and of an oxidation process for chloral hydrate are proposed. The reduction scheme supports the stepwise removal of chloride ions from the hydrated form of chloral that is electroactive in its protonated form, yielding ethanol as the final product. A rate constant for the protonation of chloral hydrate is calculated from its measured pKa value and electrochemical data. The role of hydration‐dehydration equilibria involving the reduction intermediates, which are reduced at more negative potentials than that of chloral, was concluded based on a comparison of limiting currents of chloral hydrate with those of 2,2,2‐trichloroethanol. The alcohol yields, in medium pH range a diffusion‐limited current, corresponding to cleavage of three C‐Cl bonds. This allowed the calculation of the equilibrium constant of the hydration‐dehydration equilibria. [ABSTRACT FROM AUTHOR]

In this work, a clean microwave carbothermal reduction of Sb2O3 mineral to prepare metallic antimony ingot is proposed. Response surface methodology was used to optimize condition for microwave carbothermal reduction of Sb2O3. The roasting temperature, roasting duration, carbon powder ratio and NaCl addition ratio was collected to carry out a four-factor and three-level experiment. In the optimized conditions, a >77.0% yield of antimony ingot can be obtained under roasting temperature of 730 °C, roasting time of 60min, carbon powder ratio of 0.3, NaCl addition amount of 4%. More than 99% Sb content of metallic Sb ingot is obtained in the microwave field. The mechanism of microwave carbothermal reduction of Sb2O3 was investigated by XRD, SEM-EDS and Mapping analysis, the results show that the microwave reduction process is divided into three stages based on the melting point of antimony, namely, 25 °C–400 °C, 400 °C–630 °C, and above 630 °C, which differ in terms of phase transformation. In the microwave field, the reduction of Sb2O3 to Sb particles can be completed within 15 min. Microwave metallurgical technology is conducive to the sustainable development of antimony metallurgy, and also provides a clean technology for the metallurgy industry.

Abstract CeO2 and CeO2‐based materials are widely used as catalysts and catalyst supports for a variety of chemical reactions. The ability to form oxygen vacancies plays an important role in the catalytic activities in these materials. Therefore, revealing the reduction mechanism for CeO2 is crucial to understanding the catalytic activities. In this study, shape‐controlled CeO2 nanoparticles are fabricated and the distribution of surface oxygen vacancies on the (100) and (111) surfaces is systematically studied using scanning transmission electron microscopy and electron energy‐loss spectroscopy and the response to H2 reduction treatment. It is successfully demonstrated that both catalytic activities and the ability to form oxygen vacancies are strongly dependent on the type of lattice planes. Moreover, the present results provide important insights into the reduction mechanism for CeO2, in which bulk oxygen instead of the widely believed surface capping oxygen makes no small contribution to the initial reduction step.

Microbial remediation, utilizing reduction of Cr(VI) to Cr(III), is considered a promising method for lowering toxic environmental chromium levels. In this study, a Cr(VI)-resistant fungal strain, Fusarium proliferatum S4 (F. proliferatum), was isolated from seriously chromium-polluted soil at Haibei Chemical Plant, China. This strain for treatment chromium-containing solution resulted in 100.00%, 93%, and 74% removal at initial concentrations of 10, 30, and 50 mg L−1 Cr(VI), respectively, after 12 days of treatment in a batch mode. Contributions of different cell fractions to Cr(VI) removal were explored. The Cr(VI) removal capacity of various cell components from strong to weak was as follows: cytoplasm, cell secretions, and cell debris. Observations obtained by scanning electron microscopy and transmission electron microscopy with energy dispersive X-ray spectroscopy revealed that not only the cell surfaces but also the intracellular contents were involved Cr through adsorption, reduction, or accumulation. Fourier transform infrared spectra indicated that a large number of functional groups (amino, carbonyl, carboxyl, and phosphate groups) participated in chromium binding on the cell surface. X-ray photoelectron spectroscopy confirmed the presence of Cr on the cell surface only as Cr(III). The results have important implications for an in-depth understanding of microbial chromate reduction by F. proliferatum. This study provides an insight into the microbial Cr(VI) bioreduction efficiency, and mechanisms in the chromium-contaminated environment. [ABSTRACT FROM AUTHOR]

Under the background of "carbon peaking" and "carbon neutralization", the green transformation of iron and steel enterprises is imminent. The hydrogen-rich smelting technology of blast furnaces is very important for reducing energy consumption and CO2 emission in ironmaking systems, and it is one of the important directions of green and low-carbon development of iron and steel enterprises. In this paper, the research status of the thermal state, reduction mechanism of iron-bearing burden, coke degradation behavior, and formation of the cohesive zone in various areas of blast furnace after hydrogen-rich smelting is summarized, which can make a more clear and comprehensive understanding for the effect of H2 on blast furnace ironmaking. Meanwhile, based on the current research situation, it is proposed that the following aspects should be further studied in the hydrogen-rich smelting of blast furnaces: (1) the utilization rate of hydrogen and degree of substitution for direct reduction, (2) combustion behavior of fuel in raceway, (3) control of gas flow distribution in the blast furnace, (4) operation optimization of the blast furnace. [ABSTRACT FROM AUTHOR]

High-phosphorus iron ore resource is considered a refractory iron ore because of its high-phosphorus content and complex ore phase structure. Therefore, the development of innovative technology to realize the efficient utilization of high-phosphorus iron ore resources is of theoretical and practical significance. Thus, a method for phosphorus removal by gasification in the hydrogen-rich sintering process was proposed. In this study, the reduction mechanism of phosphorus in hydrogen-rich sintering, as well as the reduction kinetics of apatite based on the non-isothermal kinetic method, was investigated. Results showed that, by increasing the reduction time from 20 to 60 min, the dephosphorization rate increased from 10.93% to 29.51%. With apatite reduction, the metal iron accumulates, and part of the reduced phosphorus gas is absorbed by the metal iron to form stable iron—phosphorus compounds, resulting in a significant reduction of the dephosphorization rate. Apatite reduction is mainly concentrated in the sintering and burning zones, and the reduced phosphorus gas moves downward along with flue gas under suction pressure and is condensed and adsorbed partly by the sintering bed when passing through the drying zone and over the wet zone. As a result, the dephosphorization rate is considerably reduced. Based on the Ozawa formula of the iso-conversion rate, the activation energy of apatite reduction is 80.42 kJ/mol. The mechanism function of apatite reduction is determined by a differential method (i.e., the Freeman-Carroll method) and an integral method (i.e., the Coats—Redfern method). The differential form of the equation is f(α) = 2(1 − α)1/2, and the integral form of the equation is G(α) = 1 − (1 − α)1/2. [ABSTRACT FROM AUTHOR]

Silicon (Si) films were obtained through aluminothermic reduction of the quartz (SiO2) substrates, where the surface of the quartz in contact with the deposited aluminum (Al) layer has been converted to film Si during high-temperature annealing following reduction reaction. X-ray diffraction (XRD) patterns and Raman spectra show dominating peaks corresponding to elemental Si in the obtained films. Energy dispersive spectroscopy (EDS), as well as XRD of the obtained Si layer, suggests that reduction products consist of mainly elemental Si mixed with oxides of Al-related phases. Both the higher reaction temperature and high initial Al-content (larger thickness of Al film in Al/SiO2 structure), studied in this paper, were found in favor of obtaining higher contents of Si in the obtained films. Thus, crystallinity and quality of the obtained Si-layer improve with the increase of both reduction temperature as well as thickness of the Al layer, as confirmed by XRD and Raman spectra. The aluminothermic reduction mechanism has been discussed using XRD as well as a ternary phase diagram of the constituent elements, obtained from EDS data. Crystalline nature (nanocrystal to microcrystal to polycrystal) and the crystalline quality of the obtained Si layers were found to be affected by the thickness of the deposited Al layer on SiO2 substrates.

The reduction of CO2 into clean energy through electro catalytic technology provides a promising solution to alleviate energy shortages. In this paper, the graphitised material-supported metal dimer used for electro catalytic reduction of CO2 was proposed, and the reduction reaction mechanism was explored by density functional theory. The results indicate that the hydrogenation reduction of CO2 tends to occur preferentially, and it was found that improving the stability of catalyst structure can reduce the free energy of reaction and improve the adsorption effect of reactants, which significantly increase the conversion efficiency of CO2. The activation of CO2 on the catalyst surface is closely related to the binding of O atoms on the metal sites, the main reduction products and their reaction pathways were clarified. The reduction over potentials of CuCo-C, CuRh-C, CuZn-C and ZnCu-C were 0.915, 0.820, 0.774, and 0.354 V, respectively, thus ZnCu-C had a lower reduction over potential and higher catalytic efficiency. [ABSTRACT FROM AUTHOR]

The thermodynamic data of iron oxides reduction reactions from the most recognized thermodynamic database (NIST‐JANAF) show remarkable difference between stoichiometric and nonstoichiometric iron oxides. Iron oxides reduction equilibria in both CO‐CO2 and H2‐H2O atmospheres are calculated with Dieckmann's and Weiss' defect models. Relevant literatures are investigated and reduction experiments are carried out to complement and interpret the newly calculated equilibrium diagram. The results suggest a conjecture of two routes for hematite reduction reactions. With the ideal and widely accepted mechanism, hematite is reduced to magnetite and then to iron below 576 °C, while the reduction route follows the sequence of Fe2O3 → Fe3−δO4 → FexO → Fe above 576 °C. With the regular but always unrecognized mechanism, the reduction process of hematite experiences Fe3O4, FeO, and Fe step by step in all possible temperature above 156 °C. In the regular mechanism, sufficient scattered impurities occupy crystal interstices of magnetite and prevent the newly produced FeO unit cell from dissolving into the solid solution of magnetite, and then the FeO will accumulate above 156 °C. Actually the regular mechanism is hard to realize and usually confused with the ideal mechanism. The presence of the regular mechanism is proved by experimental phenomena of the drop of eutectoid temperature. [ABSTRACT FROM AUTHOR]

In the advanced spent fuel cycle, the control and adjustment of neptunium valence state is greatly important for the highly efficient separation of neptunium. Hydrazine and its derivatives as salt-free reagents can selectively reduce Np(VI) to Np(V), but their reduction mechanisms are still unclear. We explored the reduction of [NpVIO2(H2O)2(NO3)2] by N2H4 and its two derivatives HOC2H4N2H3 and CHON2H3 using scalar relativistic density functional theory. The thermodynamic energy of the reactions [NpVIO2(H2O)2(NO3)2] with three reductants are sensitive to the substitution group, HOC2H4N2H3 enhances thermodynamic ability of the reaction and CHON2H3 shows contrary result. Both HOC2H4N2H3 and CHON2H3 have lower energy barrier compared to N2H4 based on the potential energy profiles (PEPs), which probably attributes to the intramolecular hydrogen bond of hydrazine derivatives. The nature of these redox reactions is that the hydrogen atom of reductants is gradually transferred to the axis oxygen atom of neptunyl, which accompanies the N–H bond dissociation and Oax–H bond formation. The reduction of Np(VI) with HOC2H4N2H3 is the most favorable reaction based on the thermodynamic and kinetic results. This work provides theoretical perspective into the reduction of Np(VI) to Np(V), which is beneficial to the development of more effective free-salt reductants for the separation of neptunium from uranium and plutonium in spent fuel reprocessing. [ABSTRACT FROM AUTHOR]

The programmed reduction of tungstates and molybdates may yield the production of an intimate mixture of metals, pseudo-alloys or composite powders. As an extension of the study of obtaining powders of tungsten-copper, molybdenum-copper and tungsten-nickel from their respective salts, in the present study the reduction of silver tungstate was performed. Considering the extreme conditions for the synthesis of W-Ag alloys in the combustion wave and the limited toolkit for the study of the associated reduction mechanism, the interaction in the Ag2WO4-Mg-C system was modeled at high heating rates closer to the heating rates of reagents in the combustion wave, namely by the high-speed temperature scanner (HSTS). For the effective study of the interaction mechanism and calculation of the kinetic parameters of the individual stages, the heating rate of the reagents was changed in a wide range (from 100 to 1200 °C min−1). The interaction scheme and the sequence of the reactions along with their starting temperatures were deduced; the nature of intermediates formed during the reduction process and the microstructure evolution were monitored. [ABSTRACT FROM AUTHOR]

The electrolytic reduction of TiO2 in LiCl–Li2O (1 wt.%) at 650 °C was investigated under a series of cathodic reduction potentials and applied charges to provide a mechanistic understanding of the electrochemical characteristics of the system. The optimal cathodic reduction potential was determined as being −0.3 V vs. Li/Li+. Li2TiO3 and LiTiO2 were structurally identified as intermediate and partial reduction products of the TiO2 electrolytic reduction. The reduction of LiTiO2 was extremely slow and reversible due to its high stability and the detrimental effect of Li2O accumulation within the solid particles. The most reduced product obtained in this study was LiTiO2, which was achieved when using 150% of the theoretical charge under the optimal reduction potential. The highest reduction extent obtained in this study was 25%. Based on theoretical DFT modeling, a detailed multistep reduction mechanism and scheme were proposed for TiO2 electrolytic reduction in LiCl–Li2O (1 wt.%) at 650 °C.

PTC-porous nano-cage with a proposed chemical structure for gold recovery and hydrogen generation with digital photographs or recovered gold. [Display omitted] • Poly(tetrakis(4-aminophenyl)methane-co-cylotriphosphazene) porous nano-cages. • Role of the amine groups and porous nano-cages for Au and Pd recovery. • Amine groups facilitate the reduction of ionic Au and Pd. • Catalytic hydrogen generation from ammonia borane hydrolysis. Designing a new material for precious metals (PMs) recovery is of ultimate significance in the quest to explore highly efficient, selective, and stable adsorbents for a sustainable economy and green environment. Herein, novel amine-rich cyclotriphosphazene poly(tetrakis(4-aminophenyl)methane-co-cylotriphosphazene)- porous nano-cages (PTC-PNC) and microspheres (PTC-MS) were synthesized for adsorption and selective recovery of Au(III) and Pd(II) in aqueous solution. A combination of the abundant amine groups and the cage-like porous morphology of PTC-PNC makes it an ideal absorbent for recovery of the Au(III) (1592 mg g−1, pH 1.0, 60 oC) and Pd(II) (1372 mg g−1, pH 1.0, 60 oC) with high selectivity which was slightly decreased up to 8-11% even in the presence of 13 co-existing metals ions while an ultra-high recovery of 99% was obtained. The unique cage-like morphology of the PTC-PNC guarantees a fast adsorption equilibrium while the adsorption isotherm specifies a pseudo-second-order kinetic behavior and Langmuir isotherm. Amine groups were the most energetically favorable sites for the capturing and chelating of Au(III) and Pd(II) ions followed by their partial reduction to Au0 and Pd0. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and high-resolution transmission electron spectroscopy (HRTEM) analysis were employed to explore interactions and reduction mechanisms during the adsorption process. Adopting the waste-to-resource approach, after Au(III) and Pd(II) recovery, these adsorbents were applied for catalytic hydrogen generation from ammonia borane (AB) hydrolysis. Due to its favorable electronic structure, the PTC-PNC@Pd exhibited a higher hydrogen generation than PTC-PNC@Au. The as-synthesized PTC-PNC could be employed as a promising material for other MPs' selective recovery and green energy generation applications. [ABSTRACT FROM AUTHOR]

Solid electrolyte interphase (SEI) plays a significant role in enhancing the stability and durability of lithium metal batteries (LMBs) by separating highly reactive lithium metal anode (LMA) from the electrolyte to avoid continuous degradation. However, the underlying reaction mechanism is still far from clear. Herein, a hybrid ab initio and reactive force field (HAIR) method is employed to extend the ab initio molecular dynamics (AIMD) to 1 ns, which provides crystal information about the reaction mechanism of elementary reactions that can explain the components and morphology evolution of SEI formation. Specifically, HAIR simulation confirms the two‐electron (2e–) reduction of ethylene carbonate (EC) by releasing CO and CO2, agreeing with phenomenal experiment observation. As the unsaturated intermediates accumulate, polymerization reactions occur, producing linear polyethylene oxide (PEO), Li2OCO2CH2CH2, Li2OCO2(CH2)4, etc., which regulate the formation of outer organic layer (OOL) that consists of linear polyethylene oxide (PEO), Li2OCO2CH2CH2, Li2OCO2(CH2)4, etc., and the inner inorganic layer (IIL) mainly consists of LiF and Li2O. Simulations at low concentration (LC, 1M) and high concentration (HC, 5M) reveal significantly different reaction pathways when HC electrolyte can significantly promote the formation of homogenous LiF that has been regarded as an important component to facilitate robust SEI. [ABSTRACT FROM AUTHOR]

Rhodopseudomonas palustris ferredoxin:NADP+ oxidoreductase (RpFNR) belongs to a novel group of thioredoxin reductase-type FNRs with partly characterized redox properties. Based on the reactions of RpFNR with the 3-acetylpyridine adenine dinucleotide phosphate redox couple, we estimated the two-electron reduction midpoint potential of the FAD cofactor to be −0.285 V. 5-Deaza-FMN-sensitized photoreduction revealed −0.017 V separation of the redox potentials between the first and second electron transfer events. We examined the mechanism of oxidation of RpFNR by several different groups of nonphysiological electron acceptors. The kcat/Km values of quinones and aromatic N-oxides toward RpFNR increase with their single-electron reduction midpoint potential. The lower reactivity, mirroring their lower electron self-exchange rate, is also seen to have a similar trend for nitroaromatic compounds. A mixed single- and two-electron reduction was characteristic of quinones, with single-electron reduction accounting for 54% of the electron flux, whereas nitroaromatics were reduced exclusively via single-electron reduction. It is highly possible that the FADH· to FAD oxidation reaction is the rate-limiting step during the reoxidation of reduced FAD. The calculated electron transfer distances in the reaction with quinones and nitroaromatics were close to those of Anabaena and Plasmodium falciparum FNRs, thus demonstrating their similar "intrinsic" reactivity. [ABSTRACT FROM AUTHOR]

In this research, the reduction mechanism of Nb(V) under various [F−]/[Nbn+] ratios (α) was investigated by a series of electrochemical techniques, such as square wave voltammetry (SWV) and chronopotentiometry (CP). We previously studied the electrode reduction process of Nb(V) and revealed that was Nb(V) → Nb(III) → Nb(I) → Nb in NaCl-KCl molten salt. It was found in this research that the electrode reduction process of Nb(V) ion was shortened to Nb(V) → Nb(III) → Nb when α was equal to 1.0; furthermore, the electrode reduction process of Nb(V) ion transforms to Nb(V) → Nb(IV) → Nb when α was greater than or equal to 5.0. Moreover, the reaction mechanism was also discussed in this work. Metallic niobium was collected on a molybdenum electrode under the condition of higher fluoride content after electrolysis in the melt. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of Zr (IV) at molybdenum and nickel electrodes was investigated by cyclic voltammetry, square-wave voltammetry, chronoamperometry, and chronopotentiometry at 1023 K to investigate the mechanism through which zirconium was electrochemically reduced. The number of electrons transferred in the two-step reduction of Zr(IV) at a molybdenum electrode in molten NaCl–KCl was calculated from the square-wave voltammetry results. Zr(IV) reduction to Zr (0) was found to be a two-step reaction described by the equations Zr(IV)+2e−→Zr(II) and Zr(II)+2e−→Zr (0). The diffusion coefficient for the transfer of Zr(IV) to the molybdenum electrode in molten NaCl–KCl was calculated from the chronoamperometry results. The phase and structure of the product of Zr(IV) reduction at a nickel electrode were determined by X-ray diffractometry and by scanning electron microscopy with energy dispersive X-ray spectroscopy, and a NiZr intermetallic compound was found. • The Zr(IV) reduction process at the molybdenum electrode had two steps. • Two electrons were transferred in each reduction step. • The potential of Zr(IV) on Ni electrode was more positive than that on Mo electrode. • NiZr alloy was prepared by potentiostatic electrolysis. [ABSTRACT FROM AUTHOR]

The mass production of graphene sheets is a prerequisite for exploiting the applications of graphene. A major focus of experimental research has been concentrated on the development of effective approaches to produce well-defined graphene in large scale. Due to its high yield and cost efficiency, chemical reduction of graphene oxide has been proofed to be one of the most feasible approaches to achieve this goal. Graphene consists almost entirely of sp2 hybridized carbon atoms, while graphene oxide additionally contains sp3 regions, oxygen functional groups and structural defects. The fundamental understanding of the mechanism of chemical reduction of graphene oxide is a key issue when preparing graphene materials via graphene oxide precursor. Although dozens of methods have been exploited to facilitate the chemical reduction of graphene, only few studies were focused on the reduction mechanism.The chemical reduction strategies of graphene oxide, and as well as their mechanisms were reviewed in this paper. It was suggested that the core issue of the reduction is how to clarify the removal of hydroxyl groups and the simultaneous restoration of a conjugated structure.