Search

In this study, we present a novel low-frequency magnetic field energy harvester (EH) employing beryllium bronze/Pb(Zr,Ti)O3 ceramic composited dual-beam structures with tip magnets attached to the inner and outer beams. This design incorporates the internal magnetic-coupled (IMC) effect, resulting in significantly enhanced coupling ability and a wide bandwidth. The validity of the IMC mechanism is confirmed through theoretical formulas and numerical simulations. By leveraging the IMC condition, the EH achieves an expanded bandwidth, which increases from 22 to 43 Hz. Moreover, the total output voltages at the inherent resonance and internal resonance are boosted by 15.4% and 32%, respectively. The performance of the IMC-EH can be further improved by increasing the number of the endmost magnets. Experimental investigations reveal that the IMC-EH generates a maximum RMS output power density of 56.25 μW Oe−2 cm−3, surpassing existing magnetically coupled piezoelectric energy harvesters. Remarkably, even under an ambient magnetic field as low as 1 Oe, the proposed IMC-EH still yields a total output power of 185 μW, sufficient to continuously power 26 LEDs in real time. This demonstrates its potential as a promising solution for low-power consumption small electronics. Furthermore, the implications of this work extend beyond its immediate benefits, as it inspires the design of future self-powered wireless sensor networks in the context of the Internet of Things. [ABSTRACT FROM AUTHOR]

This paper proposes analytical solutions for the resonant radiation performance of bending-mode magnetoelectric (ME) antennas. The strain-mediated Converse ME (CME) coupling model of bending-mode ME antennas is first established by solving nonlinear constitutive equations and bending governing equations using the elastic mechanics method. Then, the calculated magnetic flux and electric displacement are employed to propose a resonant radiation field model based on the dipole method. The numerical results for the CME coefficient show a good agreement with the experimental data. It can be observed that the volume fraction ratio of the piezoelectric layer can control the CME coefficient and radiation efficiency with the same variation trend since it can determine the bending strain via changing the location of the neutral layer of the ME antennas, which also demonstrates the strain-mediated essence of the ME antennas. In addition, the volume fraction ratio can tune the resonant frequency within a wide range. The gain of the ME antenna is stable and higher than −168 dB with the volume fraction ratio ranging from 0.2 to 0.7. The tensile stress and compressive stress have the opposite effect on the resonant frequency at low and high bias magnetic fields. Meanwhile, the tensile (compressive) stress is beneficial for both the radiation and gain in the low (high) bias field region. This model may facilitate the understanding of the bending-mode radiation mechanism of ME antennas and provide a basis for designing asymmetric ME antennas. [ABSTRACT FROM AUTHOR]

This paper presents analytical solutions for full-field radiation in magnetoelectric (ME) antennas, considering a fully magneto-elastic coupled constitutive relation. A nonlinear converse ME coupling model is established, incorporating mechanical, electric, and magnetic variables with generalized Maxwell equations. This model emphasizes the essence of ME antennas, where radiation is achieved through strain/stress-mediated coupling between different phases. The magnetic flux density and electric displacement obtained from the model are used as sources to solve the full-field radiations of ME antennas. The proposed model is validated through existing experiments and simulations, demonstrating that the radiation performance of ME antennas is strongly influenced by nonlinear magneto-elastic coupling. The material parameters and magnetic bias significantly impact the magnetic flux density and far-field radiation due to the nonlinear magnetization process. The study reveals the mechanisms behind enhanced working bandwidth and frequency tuning by examining the frequency response of the radiation impedance with material parameters. By adjusting the initial magnetization rate, saturation magnetostriction, and saturation magnetization, the radiation efficiency/gain can be increased by 340%, 108%, and 112% respectively. This model enhances our understanding of the full-field radiation of ME antennas and provides a foundation for designing tunable ME antennas. [ABSTRACT FROM AUTHOR]

This paper presents an analytical model for the near-field radiation of acoustically actuated magnetoelectric (ME) antennas considering a fully magneto-elastic coupled magnetostrictive constitutive relation. The nonlinearity of the magnetostrictive phase is introduced into the governing equation of the ME antennas using the equivalent parameter method, resulting in analytical expressions of the near-field radiation. The strain distribution in the ME antenna is calculated first and then extracted as a source for solving the magnetic flux density, energies, average radiated power, and radiation impedance. The predictions for the admittance and impedance show good agreement with simulation and experimental data, respectively. The effects of the external stimuli on the radiation performance are investigated, to theoretically evaluate the ME antennas operated in complex magnetic and stress conditions. The required magnetic bias corresponding to the maximum radiation of the ME antennas is determined, which is changed with the pre-stress. In addition, the radiation power can be improved by tensile stress before the required magnetic bias or by compressive stress after the required magnetic bias. The present model may provide a basis for the evaluation and regulation of acoustically actuated ME antenna. [ABSTRACT FROM AUTHOR]

Extraction of Mn from manganese oxide ore via sulfur-based reduction followed by acid leaching has received much attention. In this study, the mechanism on reducing manganese oxide ore with elemental sulfur was investigated. The reduction of manganese dioxide by sulfur is feasible thermodynamically, and the experimental validation proved that manganese dioxide was reduced stepwise to low-valence state in the order of MnO 2  → Mn 2 O 3  → Mn 3 O 4 (together with MnSO 4 or SO 2 ). Subsequently, Mn 3 O 4 would be reduced to form MnS or MnO, and the tendency of forming MnO was enhanced with increase in the temperature. Manganese oxide (MnO) will further react with excessive sulfur forming MnS and MnSO 4 . However, the formed MnS on the surface of the particles would inhibit further reduction or sulfidation. During the reductive roasting process, MnSO 4 as well as gaseous SO 2 were simultaneously generated. The reaction between MnS and Mn 3 O 4 occurred at temperatures over 500 °C, which facilitated producing MnO and SO 2 . The roasted product contained MnS, MnSO 4 , MnO and unreacted Mn 3 O 4 at lower temperature (<500 °C), whereas the main products were MnO and MnSO 4 at higher temperature (≥500 °C). The content of MnO increased gradually while that of MnS was decreased by increasing the roasting temperature. [ABSTRACT FROM AUTHOR]

Manganese oxide ore is one of the most important resources. Owing to the depletion of high-grade ores, attention has turned to low-grade ones containing multiple elements such as iron, silicon, and aluminum. Conventional processes for extracting manganese are characterized by high production costs, intensive energy consumption, heavy environmental issues, or high co-leaching of impurities. In this study, selective sulfation roasting–water leaching is proposed for recovering manganese from iron rich low-grade manganese oxide ores using SO 2 as reductant. Thermodynamic analysis indicated that manganese dioxide is readily transformed to sulfate. However, the sulfation of ferric oxide only occurs in the presence of both SO 2 and O 2 . The thermodynamic stability region for MnSO 4 and Fe 2 O 3 demonstrated selective sulfation of manganese dioxide is feasible. The experimental validation for sulfation roasting and water leaching revealed that 90.6% of manganese and only 3.5% of iron were extracted when sulfation roasting was conducted at 500 °C for 60 min with SO 2 partial pressure (SO 2 / (SO 2 + N 2 )) of 0.5%–1.0% (Vol.), and the leaching process was performed at 50 °C for 15 min with liquid-to-solid ratio of 5. This process is able to recover manganese from various low-grade manganese oxide ores. [ABSTRACT FROM AUTHOR]

Abstract: In recent years, the comprehensive utilization of low-grade manganese oxide ores has received much attention due to the shortage of high-grade manganese ore resources. In this study, low-grade manganese oxide ores were treated by reduction roasting using chemically pure sulfur as a reductant. Then, the roasted samples were subjected to sulfuric acid leaching to extract manganese (Mn). The effects of roasting temperature, roasting time, S/Mn mole ratio, sulfuric acid concentration, leaching temperature, stirring rate, leaching time and liquid-to-solid ratio on the Mn and Fe leaching were discussed. The leaching efficiencies of 95.6% for Mn and 14.5% for Fe were obtained under the following optimized conditions: 550°C of roasting temperature, 10min of roasting time, 0.50 of S/Mn, 1.0mol/L of sulfuric acid concentration, 25°C of leaching temperature, 200r/min of stirring rate, 5min of leaching time and 5:1 of liquid-to-solid ratio. [Copyright &y& Elsevier]

Abstract: Barium hexaaluminate (BHA) with large surface area (49 m2 g−1) is synthesized by microemulsion-mediated synthesis technique and examined as a support promoting ammonia synthesis by particulate Ru. The Ru/BHA catalyst exhibits higher activity and stability than Ba-promoted Ru/MgO, the previously most active oxide-supported catalyst system for ammonia synthesis. The rate of ammonia synthesis over Ru/BHA is 5426 μmol g−1 cat h−1 (653 K, 1.1 MPa), more than twice of that of Ba–Ru/MgO, and no decrease in the rate is observed over reaction for 80 h at 653 K and 0.1 MPa. Characterization of this catalyst system by various techniques reveals that the electronic and structural interactions between BHA and Ru particles are key factors responsible for the elevated activity and stability of this catalyst. [Copyright &y& Elsevier]

Mesostructured MnOx–Cs2O–Al2O3 nanocomposites have been synthesized by reverse microemulsion method combined with hydrothermal treatment and then applied to the catalytic combustion of methane. Compared to impregnation-derived conventional MnOx/Cs2O/Com-Al2O3 catalyst, the microemulsion-derived catalyst showed higher activity and stability for methane combustion. The T10% of the fresh and of the 72 h aged MnxO–Cs2O–Al2O3 were ∼475 and 490 °C, respectively, recommending it as a potential candidate catalyst for application in hybrid gas turbines. The homogeneous composition of the microemulsion-derived nanocomposite catalyst can hinder the loss of Cs+ and accelerate the formation of Cs–β-alumina phase, ensuring thus higher activity and stability for methane combustion. [Copyright &y& Elsevier]

The iron and steel industry is a major CO2 emitter and an important subject for the implementation of carbon emission reduction goals and tasks. Due to the complex ore composition and low iron grade, vanadium–bearing titanomagnetite smelting in a blast furnace consumes more coke and emits more carbon than in an ordinary blast furnace. Injecting hydrogen–rich gas into blast furnace can not only partially replace coke, but also reduce the carbon emission. Based on the whole furnace and zonal energy and mass balance of blast furnace, the operation window of the blast furnace smelting vanadium–bearing titanomagnetite is established in this study on the premise that the thermal state of the blast furnace is basically unchanged (raceway adiabatic flame temperature and top gas temperature). The effects of different injection amounts of hydrogen–rich gases (shale gas, coke oven gas, and hydrogen) on raceway adiabatic flame temperature and top gas temperature, and the influence of blast temperature and preheating temperature of hydrogen–rich gases on operation window are calculated and analyzed. This study provides a certain theoretical reference for the follow–up practice of hydrogen–rich smelting of vanadium–bearing titanomagnetite in blast furnace. [ABSTRACT FROM AUTHOR]

Fischer-Tropsch synthesis (FTS) converts syngas into multi-carbon products, whose distribution is highly dependent on the catalyst structure. Here, nano-iron catalysts with different silica supports were prepared, and their activities and durability for Fischer-Tropsch to olefins (FTO) process were investigated. Fe/KCC-1 demonstrated the best FTO catalytic selectivity of 25.0% for C2–4= and an olefin-to-paraffin ratio of 1.68. Its open pore structure allowed primary olefins to escape quickly from the catalyst surface, lowering the probability for secondary reactions. However, its durability was lower than Fe/SBA-15 due to coke formation, pore structure collapse and Fe particle agglomeration. The thermal stability of SBA-15 resulted in its better durability, and the encapsulated Fe particles inside the cylindrical mesopores also allowed better resistance to sintering. However, the less open structure of Fe/SBA-15 led to longer residence time for the primary olefins and increased possibility for secondary reactions, causing undesired chain growth.Graphical Abstract: Fischer-Tropsch synthesis (FTS) converts syngas into multi-carbon products, whose distribution is highly dependent on the catalyst structure. Here, nano-iron catalysts with different silica supports were prepared, and their activities and durability for Fischer-Tropsch to olefins (FTO) process were investigated. Fe/KCC-1 demonstrated the best FTO catalytic selectivity of 25.0% for C2–4= and an olefin-to-paraffin ratio of 1.68. Its open pore structure allowed primary olefins to escape quickly from the catalyst surface, lowering the probability for secondary reactions. However, its durability was lower than Fe/SBA-15 due to coke formation, pore structure collapse and Fe particle agglomeration. The thermal stability of SBA-15 resulted in its better durability, and the encapsulated Fe particles inside the cylindrical mesopores also allowed better resistance to sintering. However, the less open structure of Fe/SBA-15 led to longer residence time for the primary olefins and increased possibility for secondary reactions, causing undesired chain growth. [ABSTRACT FROM AUTHOR]

Recently, lattice defects (hydrogen vacancies, oxygen vacancies and nitrogen vacancies) have attracted significant attention due to their promoted activity of ammonia synthesis. Here, composites of CaBTO were prepared via treatment of Ba 5 Ta 4 O 15 –CaH 2 mixture in a flow of H 2 /N 2 at 600 °C for 16 h. It was found that the reduction of Ba 5 Ta 4 O 15 by CaH 2 significantly promoted the ammonia synthesis activity of Ru/Ba 5 Ta 4 O 15. The oxygen vacancies (O v) with trapped electrons were formed in CaBTO. Various characterizations and kinetic experiments indicated that O v donated electrons to Ru particles to promote the activation and dissociation of N 2 , and accepted the hydrogen atoms from Ru surface to suppress hydrogen poisoning. The lattice N3− and H− in CaBTO could also accept hydrogen or nitrogen atoms to form NH 3 , which provided more reaction pathways for ammonia synthesis and further improved the rate of ammonia synthesis. [Display omitted] • N3−, H− and O V were introduced in Ba 5 Ta 4 O 15 by reduction of Ba 5 Ta 4 O 15 with CaH 2. • Hydrogen poisoning of Ru species was alleviated through hydrogen spillover. • NH x (x = 1–3) species could form on the Ru surface and CaBTO600. [ABSTRACT FROM AUTHOR]

Anionic defects of H− (H∙O) and oxygen vacancies with trapped electrons (V∙O) have been built in the lattice of a hydrothermally derived perovskite (Ba5Nb4O15, BNO) by CaH2 reduction in Ar flow at 600 °C for 12 h. The formed anionic defects in the CaH2-reduced BNO (CaBNO) have been found to improve drastically the ammonia synthesis activity of Ru/CaBNO by donating electrons from both H∙O and/or V∙O to Ru atoms. The stoichiometry of H∙O and V∙O has been determined by TPR and TPO method, respectively. The H∙O defects have been proved to react with N2 under ammonia synthesis conditions via TPD, XPS measurements and isotope (D2) reaction, which provides secondary pathways for ammonia synthesis. Kinetic studies revealed that oxygen vacancies accept spilledover H atoms from Ru particles to alleviate the H2 poisoning effect. Cs-promoter has been demonstrated to accelerate the formation of anionic defects in CaBNO under ammonia synthesis reactions. Anionic defects (V∙O and H∙O) formed in the lattice of Ba5Nb4O15 perovskite via CaH2-reduction drastically promote the ammonia synthesis activity of Cs-Ru/CaBNO catalyst [ABSTRACT FROM AUTHOR]

Sodium sulfate has proven to be an effective additive for enhancing the reduction and metal aggregation during the carbothermic reduction of Ni laterite ore. In this study, the effect of Na 2 SO 4 on the non-isothermal reduction kinetics of Ni laterite ore with solid C was investigated. The kinetic parameters and mechanism function were determined. The reduction mechanism was also analyzed by combining X-ray diffraction analysis with evolved-gas analysis. The results indicated that the reduction process was divided into three stages on the basis of the conversion degree. The average activation energy was 323.0 kJ/mol for the initial stage of α = 0–0.40, 161.2 kJ/mol for the middle stage of α = 0.40–0.80, and 161.3 kJ/mol for the decaying stage of α = 0.80–1.00. Three-dimensional diffusion equation was determined as the mechanism function in the initial and middle stage. The chemical reaction function exhibited the best fit in the decaying stage. Unlabelled Image • The effect of sodium sulfate on the non-isothermal reduction kinetics of laterite ore is studied. • Thermogravimetry equipped with mass spectrometer is employed in this study. • The activation energy and model function are determined. • The mechanisms on non-isothermal reduction of laterite ore is revealed. [ABSTRACT FROM AUTHOR]

[Display omitted] Chlorinated volatile organic compounds (CVOCs) are a recalcitrant class of air pollutants, and the strongly oxidizing reactive oxygen species (ROS) generated in advanced oxidation processes (AOPs) are promising to degrade them. In this study, a FeOCl-loaded biomass-derived activated carbon (BAC) has been used as an adsorbent for accumulating CVOCs and catalyst for activating H 2 O 2 to construct a wet scrubber for the removal of airborne CVOCs. In addition to well-developed micropores, the BAC has macropores mimicking those of biostructures, which allows CVOCs to diffuse easily to its adsorption sites and catalytic sites. Probe experiments have revealed HO• to be the dominant ROS in the FeOCl/BAC + H 2 O 2 system. The wet scrubber performs well at pH 3 and H 2 O 2 concentrations as low as a few mM. It is capable of removing over 90% of dichloroethane, trichloroethylene, dichloromethane and chlorobenzene from air. By applying pulsed dosing or continuous dosing to replenish H 2 O 2 to maintain its appropriate concentration, the system achieves good long-term efficiency. A dichloroethane degradation pathway is proposed based on the analysis of intermediates. This work may provide inspiration for the design of catalyst exploiting the inherent structure of biomass for catalytic wet oxidation of CVOCs or other contaminants. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the non-isothermal reduction kinetics of nickel laterite with graphite was investigated under argon atmosphere. The reduction of nickel laterite was carried out at different heating rates (10, 15 and 20 K/min) and the evolved gas was detected by mass spectrometer in real time. The activation energies were determined by Kissinger-Akahira-Sunose (KAS) method and the reaction kinetics were determined by model-fitting (Coats-Redfern) method. The results showed that the reduction process can be divided into three stages according to the conversion degree (α): α = 0–0.45, α = 0.45–0.75, and α = 0.75–1.0, respectively. In the first stage, the average activation energy was 351.03 kJ/mol and the kinetic model fitted the two-dimensional diffusion function. In the second stage, the model of three-dimensional diffusion function was determined as the kinetic function and the average activation energy was 322.89 kJ/mol. In the third stage, the average activation energy was 341.45 kJ/mol and the kinetic model was in accordance with the chemical reaction function. The phase transformation as well as reaction mechanism during reduction were also analyzed which explained the reduction kinetics of nickel laterite. Graphical abstract Unlabelled Image Highlights • The non-isothermal reduction kinetics of nickel laterite with graphite was studied. • The reduction process can be divided into three stages according to the conversion degree. • The activation energy was calculated by Kissinger-Akahira-Sunose (KAS) method. • The model of reaction kinetics was determined by model-fitting (Coats-Redfern) method. [ABSTRACT FROM AUTHOR]

The radiation performance of acoustically actuated magnetoelectric (ME) antennas is originated from converse magnetoelectric (CME) effect that converts the electric field to magnetic field due to strain coupling. This paper presents a two-dimensional model for the CME effect of ME antennas with considering a fully magneto-elastic coupled characteristic of magnetostrictive materials. The nonlinear magnetostrictive relation is equivalent to a linear-like form using the equivalent parameter method. The coupled effects of magnetic bias and pre-stress on the CME coupling are discussed. The prediction for the CME coefficient shows a good agreement with the experimental data. The results indicate that pre-stress and magnetic bias have a strong-coupled effect on the CME effect. In addition, optimal loading modes are obtained for improving the CME effect. The radiations of ME antennas have not yet been obtained. Nevertheless, the results in this work may provide a basis for further investigation on the radiations. • A two-dimensional multi-field coupling model for the CME effect is proposed. • The linear-like magnetostrictive relation is derived using equivalent parameters. • The coupled effect of magnetic bias and pre-stress is discussed in detail. • The influence of the loading directions of the external stimuli is analyzed. [ABSTRACT FROM AUTHOR]

High-iron content manganese ore resources are becoming the mainstream raw ores for manganese extraction due to the depletion of high-grade manganese ores. Our previous research has reported the optimization parameters for the sintering of high-Fe manganese ore (abbr. high-Fe Mn-ore) fines. This study further investigated the consolidation behavior of high-Fe Mn-ore sinters with natural basicity. Sintering pot tests showed that the high-Fe Mn-ore sintering required high coke breeze dosage (about 9.9 wt.%). The CO content of the outlet flue gas (7.5 vol.%~8.0 vol.%) in the high-Fe Mn-ore sintering was higher than that in the ordinary iron ore sintering (1.0 vol.%~2.2 vol.%). XRD and SEM-EDS analyses indicated that the major mineral phases in the sinters included Fe-Mn oxides (FexMn3-xO4), ferrotephroite ((Fe,Mn)2SiO4), Ca-,Al-,Mn-,Fe- bearing silicate melts, and a small quantity of hausmannite (Mn3O4) and free quartz (SiO2). Optical microstructure and SEM images showed that the Fe-Mn oxides, Ca-, Al-, Mn-, Fe- bearing silicate melts and ferrotephroite particles are closely interconnected with one another. The formation of Fe-Mn oxides and ferrotephroite were beneficial to the sinter strength. Thermodynamic and phase diagram analyses further demonstrated that the major bonding phases of Fe-Mn oxides and ferrotephroite were easily formed under the strong reductive sintering atmosphere of high-Fe Mn-ores. [ABSTRACT FROM AUTHOR]

Summary: Ammonia gas (NH3) is a clean energy, as well as an efficient reduction and nitridation agent. A novel process of reduction and nitridation with NH3 followed by magnetic separation and low‐temperature selective chlorination to deal with vanadium slag has been proposed. Vanadium spinel (V‐Fe spinel, FeV2O4) is the main V‐bearing phase in vanadium slag, and its reduction and nitridation behavior with NH3 were investigated in this study. Thermodynamic analysis indicated that the reaction was feasible. The experimental results demonstrated that NH3 gas was an excellent reagent for reduction and nitridation. DFT calculation proved that NH3 molecule was easier adsorbed on V atom. The phase component of the final product was Fe/Fe4N/VNxOy, whose relative mass fractions obtained by Rietveld refinement analysis were 23.5%, 1%, and 75.5%, respectively. The evolution of iron and vanadium was in the order FeV2O4 → Fe4N/Fe6N2−3 → Fe4N/Fe and FeV2O4 → V2O3 → VNxOy, respectively. VNxOy was a solid solution, whose O content decreased gradually as the temperature and duration time increased, whereas the N content increased correspondingly. The O content can be decreased to less than 0.10 wt.% after reduction and nitridation at 800°C to 850°C for 3 h. [ABSTRACT FROM AUTHOR]

It is defined as follows HT ht Graph (3)where HT ht and HT ht represent the variances of the completely segregated and perfectly mixed states, respectively. Keywords: discrete element method; high shear mixer; Lacey index; mixing efficiency; particle mixing EN discrete element method high shear mixer Lacey index mixing efficiency particle mixing 1083 1094 12 11/02/22 20221001 NES 221001 1 Introduction Particle mixing is a critically important unit operation in the manufacturing of a wide range of high quality products, such as agricultural fertilizer ([28]), pharmaceutical powder ([20]), animal feed ([13]), food products ([8]) and mineral raw materials ([16]). [Extracted from the article]

[Display omitted] • A nanocube structure anatase-TiO 2 has been prepared by an ion exchange reaction between F- and H+. • The TiO 2 has an approximate amount of oxygen vacancies as Degussa-P25. • The surface of TiO 2 contains abundant hydroxyl to the extent that it changes the reaction pathway of CO 2 methanation. • The CO 2 conversion of Ru/TiO 2 catalyst could exceed that of Ru/Deggusa-P25 by 38% and the CH 4 formation rate of Ru/TiO 2 catalyst could exceed that of Ru/Deggusa-P25 by 35%. In the present study, an anatase-TiO 2 abundant in oxygen vacancies and hydroxyl was successfully designed and synthesized by introducing NaBH 4 , and loading Ru on it for application of CO 2 hydrogenation to CH 4. Compared with the conventional cascade of CO-mediated reactions of traditional Ru/TiO 2 , the Ru/TiO 2 we prepared changes the reaction pathway of CO 2 hydrogenation through abundant hydroxyl on the surface of underlying TiO 2. The hydroxyl was formed by ion exchange of F- in TiOF 2 and H- in NaBH 4 , and was a key factor in the CO 2 methanation activity of the Ru/TiO 2 we prepared beyond that of Ru/Deggusa-P25. The CO 2 conversion of the Ru/TiO 2 we prepared exceeded that of Ru/Deggusa-P25 by 38% and the CH 4 formation rate of the Ru/TiO 2 we prepared exceeded that of Ru/Deggusa-P25 by 35% at 300 °C. [ABSTRACT FROM AUTHOR]

• Developed a novel method for efficient zinc extraction from EAFD. • Achieved impressive extraction rates of 95.33% for zinc and 0.17% for iron. • Revealed the reactions and phase transformations involved in zinc extraction. • Successfully elucidated the mechanism of zinc and iron extraction and separation. Electric arc furnace dust (EAFD) is a hazardous solid waste generated as a byproduct in the steelmaking process, containing significant amounts of zinc and iron, making it a primary secondary source of zinc. The separation of zinc and iron in an environmentally-friendly and efficient manner poses a crucial technological challenge for the safe disposal and resource utilization of EAFD, facilitating the recovery of valuable zinc and the direct reuse of iron as raw materials for ironmaking. In this study, a novel method for restructuring zinc-bearing phases into sulfated compounds through low-temperature roasting by introducing FeS in EAFD were proposed. Simultaneously, the iron-containing phases undergo a transformation into Fe 2 O 3. Subsequently, efficient separation of zinc and iron is achieved through a leaching process using dilute sulfuric acid. The conditions for the theoretical transformation of zinc-containing phases into ZnSO 4 and iron-containing phases into Fe 2 O 3 in EAFD were determined by thermodynamic calculations incorporating FeS. The temperature range for sulfation calcination was determined to be within 550–700 °C based on TG-DSC analysis and the evaluation of SO 2 release during the decomposition of FeS. The optimal conditions for the roasting process were determined as an E/F ratio of 1:3, a temperature of 650 °C, and a duration of 3 h. In addition, the optimal conditions for the leaching process were determined as the addition of 1 mL of 1 M H 2 SO 4 and a liquid–solid ratio of 25 mL/g. Under these conditions, the extractions of Zn and Fe reached 95.33 % and 0.17 %, respectively. The mechanism of phase reconstruction from zinc-containing phases to sulfate phases in EAFD was thoroughly analyzed, revealing that the Zn species in EAFD were transformed into Zn 3 O(SO 4) 2 through solid–solid and gas–solid reactions, while the majority of Fe species in EAFD and FeS were converted into Fe 2 O 3. Effective separation of zinc and iron was achieved by dissolving Zn 3 O(SO 4) 2 in diluted sulfuric acid while retaining Fe 2 O 3 in the residue. This study provides a fresh perspective on the recovery of zinc from zinc-containing solid waste resources, offering significant potential for the sustainable management and utilization of EAFD. [ABSTRACT FROM AUTHOR]

[Display omitted] • The porous graphitized carbon (PGC) loaded with CoS was successfully prepared. • Wet scrubber containing CoS/PGC and PMS was effective in chlorobenzene removal. • Intermittent or continuous PMS supplementation allowed long-term CVOCs removal. • SO 4 •- and HO• play a dominant role for CVOCs degradation. Chlorobenzene (CB) is a typical example of chlorinated volatile organic compounds (CVOCs) that require pollution control. Using wet scrubbers coupled with advanced oxidation processes (AOPs) has become a promising technique to degrade gaseous CVOCs. Here, a CoS-loaded porous graphitized carbon (PGC) served as an adsorbent for CVOCs and a catalyst to activate peroxymonosulfate (PMS) to construct a wet scrubber for CB degradation. CoS/PGC exhibited excellent catalytic performance at pH 9.0; a 0.1 g/L CoS/PGC dosage and a 10 mM initial PMS concentration achieved 90% CB (25 ppmv) removal within 500 min. Electron spin resonance and quenching experiments identified hydroxyl radicals and sulfate radicals as the main reactive oxygen species that removed CB. In addition, we proposed possible CB degradation pathways by intermediates identified using liquid chromatography-mass spectrometry and density functional theory calculations. Electrochemical experimental results such as cyclic voltammetry and Nyquist proved that CoS/PGC has superior electron transport capacity compared to CoS. A possible catalytic mechanism for CB removal in CoS/PGC + PMS system was proposed by ESR and XPS spectra. By using continuous dosing or pulsed dosing to replenish PMS to maintain its suitable concentration, the system achieves a commendable long-term efficiency. Moreover, this catalyst displayed excellent recyclability and universal applicability to treat various gaseous CVOCs as well as the scrubbing solution replacement with tap water for efficient CB removal. This study may provide new fundamental insights into the PGC-supported catalysts for wet oxidation of CVOCs or other contaminants. [ABSTRACT FROM AUTHOR]

[Display omitted] The numerous oxygenated functional groups on graphite oxide (GO) make it a promising adsorbent for toxic heavy metals in water. However, the GO prepared from natural graphite is water-soluble after exfoliation, making its recovery for reuse extremely difficult. In this study, porous graphitized carbon (PGC) was oxidized to fabricate a GO-like material, PGCO. The PGCO showed an O/C molar ratio of 0.63, and 8.4% of the surface carbon species were carboxyl, exhibiting enhanced oxidation degree compared to GO. The small PGCO sheets were intensely aggregated chemically, yielding an insoluble solid easily separable from water by sedimentation or filtration. Batch adsorption experiments demonstrated that the PGCO afforded significantly higher removal efficiencies for heavy metals than GO, owing to the former's greater functionalization with oxygenated groups. An isotherm study suggested that the adsorption obeyed the Langmuir model, and the derived maximum adsorption capacities for Cr3+, Pb2+, Cu2+, Cd2+, Zn2+, and Ni2+ were 119.6, 377.1, 99.1, 65.2, 53.0, and 58.1 mg/g, respectively. Furthermore, the spent PGCO was successively regenerated by acid treatment. The results of the study indicate that PGCO could be an alternative adsorbent for remediating toxic metal-contaminated waters. [ABSTRACT FROM AUTHOR]

Blast furnace process is the main approach for utilizing vanadium–titanium magnetite (VTM) and VTM pellet is an important burden due to its excellent performance. In this paper, the softening–melting behavior of VTM pellets was investigated. The softening, melting temperature interval and permeability index were obtained as 75 °C, 181 °C and 507 kPa·°C, respectively. Ti–bearing components in pellets were transformed in the order of Fe 2 TiO 5 → Fe 3-x Ti x O 4 → FeTiO 3 → Mg x Ti 3-x O 5 and TiC. Hematite was reduced stepwise to metallic iron entering metallic fraction while most of titanium entered the slag phase. Wustite was an important component during slag evolution. The slag phase mainly consisted of spinel, silicates and wustite, in which the FeO content gradually decreased during the slag evolution process. Anosovite and silicate were the main phases in the slag fraction at the dripping temperature of 1441 °C. Titanium carbide (TiC) was also verified, which was an unfavorable product for the slag properties. [Display omitted] • The characteristic temperatures and temperature intervals of softening and melting are obtained. • The phase transformation of VTM pellets during softening–melting process is investigated. • The morphology transition and slag evolution process is discussed. • The migration behavior of titanium during softening–melting process is revealed. [ABSTRACT FROM AUTHOR]

Ferrochromium nitride is an important alloying additive for smelting nitrogen–containing steel. Preparing nitrides by using ammonia gas as reducing and nitriding agent is characterized by high–efficiency and carbon free. In this study, the reaction behavior between chromite spinel and ammonia gas was investigated. Thermodynamic analysis revealed that the reaction was feasible. The transformation of chromite spinel as well as the final products were dependent on reaction temperature, time and input fraction of ammonia gas. The experimental results proved the effect of reaction parameters on the reduction and nitridation process. Chromite spinel was reduced and nitrided to form metallic iron and CrN at temperatures below 950 °C, while metallic iron and Cr 2 N were the main products at 1000 °C. XPS analysis also proved the existence of CrN and Cr 2 N. Ferrochromium nitride with N content treater than 15 wt% was obtained when reducing above 950 °C for 3 h. [Display omitted] • Ammonia gas is a high-efficiency and carbon-free agent that is used for reducing and nitriding. • The transformation of chromite spinel is revealed in this study. • Ferrochromium nitride is prepared by using ammonia gas as reducing and nitriding agent. • Mechanism on reaction between chromite spinel and ammonia gas is revealed. [ABSTRACT FROM AUTHOR]

• This work revealed the law of gas sulfides release during the reduction process of blast furnace raw materials. • The precipitation of sulfur during the reaction of coke and sinter in reducing atmosphere was divided into two stages. • Low temperatures favored the generation of H 2 S, while high temperatures promoted the generation of COS. Understanding the transformation behavior of sulfides in the blast furnace raw materials during the ironmaking process is crucial for controlling the form and emission of gaseous sulfides in the blast furnace top gas. This study investigates the reactions of coke and sinter at different reducing atmosphere ranging from 200 °C to 1000 °C by using of thermogravimetry and mass spectrometry (TG-MS). Additionally, thermodynamic theoretical calculations were performed to enhance the understanding of the reaction behavior. The results showed that the mixed sinter and coke started to generate H 2 S at 100 °C under the mixed H 2 -CO atmosphere and reached the peak between 350 and 400 °C. With the increase of H 2 concentration, the peak temperature of H 2 S generation initially decreased and then increased, with the lowest peak temperature observed under a 50% H 2 -50% CO atmosphere. Furthermore, COS generation started around 300 °C and reached its peak at approximately 800 °C. The peak content of COS generation increased as the CO concentration. Low temperatures favored the generation of H 2 S from the mixed sinter and coke, while high temperatures were conducive to the generation of COS. [ABSTRACT FROM AUTHOR]

• Isothermal kinetics of reduction and nitridation of ilmenite concentrate by ammonia gas is studied. • Both model–free and model–fitting methods are used to compare the isothermal kinetics. • The mechanism function and apparent activation energy of the reduction and nitridation stages are obtained. • The mechanism on reduction and nitridation is discussed. Low-temperature chlorination is considered a suitable process for ilmenite containing high contents of MgO and CaO. However, reduction carbonization or nitridation is essential to convert titanium oxide to carbide or nitride, which can be enriched by magnetic separation. In this paper, the isothermal reduction–nitridation kinetics of Panzhihua ilmenite concentrate in an ammonia atmosphere was investigated. Both model–free and model–fitting methods were used to compare the isothermal kinetics. The reaction process can be divided into two successive stages: the reduction reaction and the nitridation reaction. The average apparent activation energy for the reduction reaction was 139.63 kJ/mol, obtained by the model–free method. The reduction process can also be subdivided into two stages by the model–fitting method. The chemical reaction (G(α) = 1–(1– α)1/3 = kt) and three–dimensional diffusion (G (α) = [1–(1– α)1/3]2 = kt) were identified as the mechanism function for the reduction process. The activation energies of these two stages were 121.73 kJ/mol and 141.40 kJ/mol, respectively. The function G(α) = 1–(1– α)1/3 = kt , which also corresponds to the chemical reaction mechanism (R 3), exhibited the best fit for the nitridation stage. The corresponding activation energy was 32.10 kJ/mol. Metallic iron and Ti 3 O 5 were formed in the reduction stage, while Ti 3 O 5 was then transformed to Ti(N,O) in the nitridation stage. [ABSTRACT FROM AUTHOR]

• Sr 2 Ta 2 O 7 was used for the first time to support Ru catalyst for ammonia synthesis. • Hydrogen poisoning of Ru species was alleviated through hydrogen spillover. • Loading promoter Cs remarkably improved ammonia synthesis activity of Ru/Sr 2 Ta 2 O 7. • Both promoters and the oxygen vacancies can donate electrons to the Ru. In this work, strontium tantalate (Sr 2 Ta 2 O 7) nanowires were used for the first time as a support of ruthenium catalysts for ammonia synthesis. The highest ammonia synthesis activity of 1582 μmol g−1 cat h−1 was observed with Ru/Sr 2 Ta 2 O 7 catalysts prepared with molar ratio of Sr(OH) 2 /Ta 2 O 5 at 4. After loading promoters, the ammonia synthesis activity was significantly improved to 4856, 5004 and 5038 μmol g−1 cat h−1 for K-, Rb- and Cs- modified Ru/Sr 2 Ta 2 O 7 catalysts. Characterization and kinetic experiments indicate that the improved ammonia synthesis rate of promoters-Ru/Sr 2 Ta 2 O 7 catalysts was attributable to the combined effect of alleviated hydrogen poisoning through the promotion of hydrogen spillover from Ru species to support of Sr 2 Ta 2 O 7 and enhanced activation of N 2 due to increased electron density of Ru sites because of electron donation from introduced oxygen vacancies and promoters. The study not only clarifies the role of promoters in ammonia synthesis, but also provides an excellent Ru catalyst on Sr 2 Ta 2 O 7 nanowires for ammonia synthesis. [ABSTRACT FROM AUTHOR]

Ammonia gas can be simultaneously used as a reductant and nitrogen source to prepare TiN from titania. In this work, the mechanisms on reduction and nitridation of micrometer‐sized anatase with ammonia gas have been investigated, using both thermodynamic and experimental studies. The thermodynamic analysis indicated that reduction and nitridation of TiO2 by NH3 was feasible. Anatase will undergo different paths to form TiN, depending on the reaction temperature. Upon heating, NH3 was seen to partially decompose into N2 and H2, although the actual NH3 decomposition ratio was less than the theoretical value. The experimental results indicated that the obtained titanium nitride was non‐stoichiometric (TiNxO1−x, x ≤ 1), as it contained a certain amount of oxygen. Based on the phase transformation and X‐ray photoelectron spectroscopy analysis, the reduction and nitridation routes were deduced: TiO2 reacted with NH3 to form TiNxO1−x directly, at lower temperatures, and followed the path TiO2 → TinO2n−1 → TiNxO1−x, at higher temperatures. TinO2n−1 was determined to be Ti4O7 and Ti3O5 at 1100°C and 1200°C, respectively. Reaction temperature and time significantly affected the oxygen and nitrogen contents in TiNxO1−x, with the lattice parameter of roasted products gradually increasing—approaching those of pure TiN—with an increase in reaction temperature and holding time. At the same time, the content of oxygen in TiNxO1−x decreased, and its nitrogen content correspondingly increased. [ABSTRACT FROM AUTHOR]

Strong metal–support interaction (SMSI) over Ru/CaAlOx was constructed by utilizing the surface structural reconstruction of Ca–Al layered double hydroxides (LDHs) in aqueous solution and their subsequent hydroxide-to-oxide transformations. Ru nanoparticles were found to uniformly embed with CaAlOx. The electronic interactions and changes in CO adsorption behavior confirmed the SMSI state between Ru and CaAlOx. Owing to SMSI, the as-prepared Ru/CaAlOx showed improved catalytic activity in the decomposition of ammonia, especially at a relatively low temperature. [ABSTRACT FROM AUTHOR]

We investigate the isothermal kinetics of the reduction and nitridation of V 2 O 3 using NH 3. The reaction mechanism is also discussed based on the thermodynamic and experimental results. The reaction procedure between V 2 O 3 and NH 3 can be divided into two stages. The first stage is mainly the deoxygenation process, whereas the second is the nitridation process. The deoxygenation process follows a two-dimensional phase boundary reaction model, and a modified integrated model (IM + diffusion) was proved to be the best function at temperatures above 1023 K. For the second stage, the three-dimensional diffusion model is determined as the mechanism function. Thermodynamic analysis predicts the feasibility between V 2 O 3 and NH 3 to form VN. The VN product is a solid solution (VN x O y) (0 < x,y < 1, x + y = 1), which can be formed at 873 K. The Rietveld refinement analysis indicates the N content of VN x O y gradually increases with increasing temperature. The highest N content is approximately 15.83% at 1073 K for 2 h. [Display omitted] • Ammonia (NH 3) gas is a high-efficiency and carbon-free agent that is used for reducing and nitriding. • Vanadium nitride is synthesized by gas-based reduction and nitridation. • The chemical reaction kinetics between V 2 O 3 and NH 3 is firstly investigated. • The reduction and nitridation mechanism of preparing VN is also discussed. [ABSTRACT FROM AUTHOR]

Hydroxy double salts (HDSs) have shown enormous potential for removing dyes from wastewater. However, the powder form of HDSs limits their potential in commercial applications. Herein, we proposed a facile one-step route to incorporate CuZn-HDS into the copper alginate matrix for methyl orange removal. This strategy could not only shape CuZn-HDS to beads but also significantly enhance the adsorption ability of the matrix. The obtained composite hydrogel beads displayed high water stability and excellent adsorption performance for MO, with more than 98% of MO being removed by CuZn-HDS/Alg-0.5. The maximum adsorption capacity of CuZn-HDS/Alg-0.5 for MO was 763.3 mg·g−1 at 298 K. Besides, the adsorption process matched the pseudo-second-order kinetic model and fitted well with the Freundlich model, suggesting that the adsorption of MO onto CuZn-HDS/Alg-0.5 was a multilayer chemical adsorption process. More importantly, CuZn-HDS/Alg-0.5 could selectively adsorb MO from MO & RhB (Rhodamine B) and MO & MB (Methylene blue) mixed solution. Mechanism studies indicated that the removal of MO was attributed to the electrostatic interaction, complexation interaction and ion exchange interaction between MO and CuZn-HDS/Alg-0.5. This work opens a new route for developing eco-friendly and efficient adsorbents to remove dyes from wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

Wet scrubbing coupled with adsorption-enhanced heterogeneous advanced oxidation processes (AOPs) are promising approaches to the treatment of chlorinated volatile organic compounds (CVOCs). However, microporous activated carbon-based adsorbents and catalyst supports have the disadvantage of difficult molecule diffusion. Herein, we have demonstrated that porous graphitized carbon (PGC) allowed faster intra-particle diffusion of organic molecules due to its well-developed mesoporous structure. Therefore, a wet scrubbing system containing H 2 O 2 and a PGC-supported FeOCl catalyst has been developed to effectively remove gaseous dichloroethane, trichloroethylene, dichloromethane and chlorobenzene. The scrubber performed well at pH 3.0 using a FeOCl/PGC dosage of 0.2 g/L and initial H 2 O 2 concentration of 40 mM. Its good long-term performance was achieved by replenishing H 2 O 2 to maintain a suitable concentration. The degradation pathways of dichloroethane have been proposed using a combination of intermediate analysis and density functional theory calculations. PGC-supported catalysts may be desirable bifunctional adsorbent-catalyst materials for wet scrubbing of CVOCs. [Display omitted] • Porous graphitized carbon (PGC) has well-developed mesopores. • Mesopores allows for easy intra-particle diffusion of dissolved CVOCs. • Wet scrubber containing FeOCl/PGC and H 2 O 2 efficiently removes gaseous CVOCs. • Long-term wet scrubbing performance is achieved by replenishing H 2 O 2. • HO• plays a dominant role in FeOCl/PGC-catalyzed peroxide oxidation of CVOCs. [ABSTRACT FROM AUTHOR]

Abstract The thermal behavior of poplar-fat coal (biomass-coal) blends and organic functional structure of formed coal-char in the co-pyrolysis temperature were investigated using Thermogravimetric analyzer, Differential scanning calorimetry, Mass spectrometry and Attenuated total reflection Fourier transform infrared spectroscopy analysis. Furthermore, the interactions between poplar and coal during co-pyrolysis were deduced. The results indicate that poplar decomposed prior to the decomposition of fat coal is not surprising, but results also indicate that the presence of poplar enhanced the thermal decomposition of fat coal at low temperature. The occurring interactions showed positive and negative effects with increasing temperature, which could be explained by chemical reaction and physical interaction, respectively. In the blends, these interactions lowered the apparent activation energy and frequency factor. The added poplar had a positive effect on decomposition of the organic functional groups. Interactions would indirectly cause higher hydrocarbon-generating potential and thermal maturity, and reduced aliphatic chains length and aromaticity. The synergistic effects between fat coal and poplar during co-pyrolysis occurred mainly at lower temperature. For the better application of poplar-fat coal blends, the suitable blending ratio of poplar to coal is below 16%. In addition, the pyrolysis temperature should be kept in 345–390 °C to obtain biomass-coal tar. Graphical abstract Image 102942 Highlights • Interactions of biomass-coal blends during co-pyrolysis were studied using TGA. • Kinetics and char structure in the co-pyrolysis temperature were evaluated. • Interactions presented positive and negative effects with increasing temperature. • Interactions lowered the apparent activation energy and frequency factor. • Interactions caused higher A -factor, C -factor and reduced CH 2 /CH 3 and A ar / A al values. [ABSTRACT FROM AUTHOR]

Abstract The reduction of metal oxides by hydrogen is a very significant reaction in metallurgical industries. Particularly, hydrogen reduction is one of the effective methods to reduce CO 2 emission in iron and steel industry. The mathematical modeling of H 2 reduction process would help to define the operating parameters and to get a better control of the reduction process. In this study, a new kinetic model regarding hydrogen reduction of metal oxides controlled by external gas diffusion has been proposed. The model has incorporated numbers of parameters such as temperature, size of the metal oxides, diffusion coefficient constant, hydrogen partial pressure, density of metal oxides and time. Furthermore, the shape of metal oxides (spherical, cylindrical, lamellar particles) was considered as well, and the models for the reduction of metal oxides with different shapes were combined to a formula. Also, the developed model can be applied to describe the reduction kinetics under both isothermal and non-isothermal conditions. Because the model is in the analytic function, therefore, it is convenient for usage and theoretical analysis. Application of the developed model to practical systems validated that its predicted values agreed very well with the experimental data. Highlights • Kinetic model for the external gas diffusion controlling reduction was proposed. • The model is in the analytic function and is convenient for theoretical analysis. • The shape of metal oxides was considered. • The models for different shapes were combined to a formula. [ABSTRACT FROM AUTHOR]

Power ultrasonic vibration was applied to the solidification of calcium ferrite (CF) melt in this study. The results indicated that power ultrasound can promote the formation of CF by accelerating the solidification process. Ultrasonic vibration greatly refined the CF grains, resulting the grain size decreased from 1893 to 437 μm. Meanwhile, ultrasonic vibration significantly enhanced the compressive strength, reduced the reduction time and improved the reducibility of CF slags. With ultrasonic treatment, the ultimate compressive strength of samples increased from 37.5 to 67.8 MPa, and the reduction time decreased from 225 to 136 min. [ABSTRACT FROM AUTHOR]

Strontium niobates with different crystalline structure and morphology have been prepared via a hydrothermal method and applied as a support for ruthenium catalyst in ammonia synthesis. The sample synthesized with a nominal Sr/Nb = 2.0, having a pure Sr 2 Nb 2 O 7 crystalline phase and specific surface area of 87 m 2  g −1 , exhibits the best performance as support for Ru catalyst. The flake-structured Sr 2 Nb 2 O 7 substrate induced epitaxial growth of truncated pyramid shaped ruthenium nanoparticles with a dispersion as high as 93%, which have abundant steps and B 5 sites playing a key role in ammonia synthesis catalysis. Adding Cs- or Ba-promoter enhanced the activity of Ru/Sr 2 Nb 2 O 7 catalyst drastically. The highest ammonia synthesis rate over 8Cs- or 4Ba-2 wt%Ru/Sr 2 Nb 2 O 7 was 4986 and 2317 (μmol g −1 cat h −1 ) at 0.1 MPa and 673 K, respectively. In addition, both catalysts were stable over reaction for 72 h at 673 K and 0.1 MPa. Thus, the synthesized Sr 2 Nb 2 O 7 is expected to be a practically promising oxide support for ruthenium ammonia synthesis catalsyts. [ABSTRACT FROM AUTHOR]

Structured catalysts and reactors have wide applications in environmental remediation and production of important energy-related chemicals. In thermal catalytic processes, external heater are often required to raise the temperature and ignite the reactions, which might lead to huge setups. Herein, we introduce a novel Joule-heat-ignition catalytic reactor. Using Fe-Cr-Al alloy as catalyst substrate, electric currents can pass directly through the substrate, generating Joule heat and bringing the catalysts to the target temperatures. Therefore, the setup can be simplified by omitting the additional heater; the heat produced inside the substrates can be transferred directly to the catalyst coat to achieve rapid ignition; and the reaction temperature can be flexibly controlled by adjusting the input power. In this work, we loaded manganese oxide catalyst onto an alloy wire and used it to build a Joule-heat-ignition reactor for the catalytic oxidation of carbon monoxide and toluene. The anodization pretreatment generated channels on the alloy surface, which effectively enhanced the catalyst loading. The use of alumina as a secondary support also favored catalyst loading and promoted catalyst dispersion. By adding proper amounts of zirconium, the mechanical stability of the catalyst layer increased. The Joule-heat-ignition catalytic system might provide some inspiration in related environmental catalysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bamboo-derived porous graphitized carbon is prepared from biomass using simple chemical reagents. • BPGC can have a high specific surface area while having a good degree of graphitization. • The mechanism of BPGC's excellent adsorption effect was revealed by DFT calculation. • BPGC maintains high VOCs adsorption capacity and good recycling performance even under hydrophobic conditions. Biomass-derived activated carbons (BACs) are often used as green adsorbents for the removal of VOCs, however, their abundant surface functional groups severely reduced their adsorption selectivity under humid conditions. In this study, hydrophobic bamboo-derived porous graphitized carbons (BPGCs) were prepared using a combined catalytic graphitization method. The optimal micro-mesoporous BPGC had a large specific surface area of 2181 m2/g and a low surface O/C ratio of 0.038. Under dry conditions, its adsorption capacities for toluene, cyclohexane and ethanol were 6.7, 3.8 and 2.4 mmol/g, respectively. At 80 % relative humidity, its adsorption capacities for toluene and cyclohexane remained 82 % and 66 %, while the uptake of ethanol even increased by 33 %. In the two-component adsorption test, BPGC showed a high selectivity for toluene adsorption over ethanol, with 198 times more toluene than ethanol. The adsorption mechanism at the microscopic molecular level was revealed by DFT calculation. The abundant π electrons and high polarizability of BPGC allow for strong π-π interactions and dispersion forces with non-polar organics, while the abundant oxygen-containing groups on BAC have strong adsorption force on water. The absorption of ethanol by capillary condensed water in mesopores of BPGC may contribute to its increased uptake under humid conditions. BPGC allowed for faster adsorption kinetics than activated carbon. More than 90 % of the adsorbed toluene was desorbed from BPGC at 90 °C. Owing to abundant renewable raw materials, excellent hydrophobicity and desirable textural properties, BPGCs may be promising adsorbents. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel two-step route was proposed to prepare NH 2 -MIL-53(Fe) with energy-saving, simplicity of operation, and high efficiency. • NH 2 -MIL-53(Fe) showed an excellent adsorption capacity towards CR (1877 mg·g−1). • Highly efficient removal of CR was achieved even in the high saline medium. • The excellent stability and reusability of NH 2 -MIL-53(Fe) facilitated its practical application. • The π-π stacking interactions, hydrogen bonds and electrostatic interactions were proposed as the potential adsorption mechanisms. Metal-organic frameworks (MOFs) have shown attractive advantages in adsorbing dyes from wastewater. However, their complex synthesis processes and poor stability have limited their applications. Herein, we proposed a novel two-step route to prepare NH 2 -MIL-53(Fe) at room temperature and investigated its dye adsorption performance. The prepared NH 2 -MIL-53(Fe) displayed high water stability in the pH range of 3–11. Moreover, NH 2 -MIL-53(Fe) showed a significantly higher adsorption capacity and faster adsorption rate towards congo red (CR) than the other selected dyes, with more than 99 % of CR being removed by NH 2 -MIL-53(Fe) within 20 min. The maximum adsorption capacity of NH 2 -MIL-53(Fe) for CR was 1877 mg·g−1. Besides, the removal efficiency of CR could maintain higher than 80 % within the tested pH range (3 to 11), and removal efficiency was consistently higher than 95 % at different NaCl concentrations (0 to 0.4 M). The dynamic CR adsorption process matched the pseudo-second-order kinetic model and fitted well using the Langmuir model, suggesting that the adsorption of CR onto NH 2 -MIL-53(Fe) was a monomolecular-layer chemical adsorption process. More importantly, NH 2 -MIL-53(Fe) showed high removal efficiency and good reusability towards CR in both synthetic and model wastewater. Mechanistic studies suggested that the removal of CR was attributed to the synergistic effects of the π-π stacking interactions, hydrogen bonds and electrostatic interactions between CR and NH 2 -MIL-53(Fe). Overall, the present study provides a novel strategy for the facile synthesis of NH 2 -MIL-53(Fe), highlights the excellent adsorption performance and reusability towards CR and underlies the adsorption mechanisms involved. [ABSTRACT FROM AUTHOR]

Various value-added chemicals such as formic acid, carbon monoxide, methane, methanol, have been obtained using CO 2 as a feedstock. However, formaldehyde generation from CO 2 is less reported. Here, we performed CO 2 hydrogenation with H 2 in additive-free water and used layered double hydroxide supported Ru as the heterogeneous catalyst. It was found that gaseous CO 2 and H 2 could be efficiently and selectively converted to formaldehyde dissolved in water even at room temperature with ambient pressure. The highest gaseous CO 2 conversion of 89.7% and a formaldehyde yield of 58.7% were achieved using a Ru/LDH-red catalyst in water at 30 °C with 10 bar CO 2 and 10 bar H 2. Combined with experimental and theoretical studies, HCOOH was found as the important reaction intermediate. The rich surface –OH of LDH and hybrid electronic state of Ru over Ru/LDH-red catalyst resulted in highly efficient HCHO formation. Our findings offer opportunities to one energy-efficient formaldehyde synthesis method. [Display omitted] • Formaldehyde was formed from aqueous CO 2 over a Ru/LDH catalyst under mild conditions. • CO 2 reduction activity and selectivity was regulated by the states of Ru. • The catalytic route was illustrated by DRIFTs measurements and DFT calculations. • Formic acid is one important intermediate during CO 2 hydrogenation to formaldehyde. [ABSTRACT FROM AUTHOR]

[Display omitted] • Silica-supported nano-Fe 2 O 3 for FTS was prepared by colloidal deposition method. • Nano-Fe/silica showed higher selectivity to light olefins than impregnated catalyst. • Nano-Fe/silica exhibited significantly superior durability over impregnated catalyst. • Nano-Fe particles were geometrically favorable for coking resistance. Nano-iron catalysts exhibit good performances in the Fischer–Tropsch synthesis to lower olefins (FTO), however, there is still a lack of simple methods for their preparation. In this work, we introduced a facile colloidal deposition (CD) method to fabricate silica-supported Fe 2 O 3 nanoparticles using a colloidal solution readily prepared from ferric hydroxide. With increasing the Fe loading from 16.3 % to 31.6 %, the Fe 2 O 3 particle size increased from 1.3 to 6.1 nm. The catalytic performances in FTO were tested at a H 2 /CO molar ratio of 1. At a Fe loading of 30.4 %, the catalyst having a particle size of 4.7 nm showed the highest lower olefin selectivity and the lowest CO 2 selectivity, outperforming analogs prepared by impregnation method. Furthermore, this catalyst showed good stability in a 200-hour durability test, while the impregnated analogue quickly deactivated due to serious coking. Presumably, the effective contact areas between the nanoparticles and the generated carbon sheets are geometrically small, which results in weak van der Waals forces between them, preventing the former from being heavily covered by the latter. Besides, from the point of view of the carbide decomposition mechanism of coking, due to the relatively low volume to surface area ratios of the intermediate carbide nanoparticles, the surface concentrations of carbon atoms released from them are low, which delays the coke formation. This study may provide a simple method to fabricate supported nano-iron catalysts, and cast some light on understanding catalyst durability in FTO. [ABSTRACT FROM AUTHOR]

Nanosized Co 3 O 4 catalyst was prepared through a dispersion–precipitation method involving a reaction between wet cobalt hydroxide and acetic acid, which forms a colloidal dispersion, and subsequent dilution, which destabilizes and precipitates the colloidal particles. The catalyst had a particle size of 5–15 nm and a specific surface area of 82 m 2 /g. Compared with the analogue prepared by conventional alkali-induced precipitation method, the nanosized catalyst was more reducible and contained a larger amount of active surface oxygen species, as revealed by experiments using temperature-programmed reduction in hydrogen and temperature-programmed desorption of oxygen. The oxygen species could contribute to the observed higher activity in the catalytic oxidation of carbon monoxide and propane. In addition, a kinetics study revealed that the apparent activation energies for carbon monoxide and propane oxidation over the catalyst were 34.0 and 49.5 kJ/mol, respectively, much lower than those over the analogue (54.7 and 71.1 kJ/mol, respectively). Furthermore, a long-term test (76 h) showed that the nanosized catalyst is highly stable. [ABSTRACT FROM AUTHOR]

Controllable synthesis of Ru nanocrystallites on graphene substrate using polyol methods was reported herein. The zeta potential of graphene oxide dispersed in polyols is found to play a key role in tailoring the morphology and oxidation state of Ru nanocrystallites on graphene substrate. Negatively charged graphene oxide can coordinate with Ru precursors via its carboxylic acid groups to form C-O-Ru complexes, leading to the epitaxial growth of hexagonally shaped cationic ruthenium nanocrystallites of 3-5 nm, which shows high catalytic activities for ammonia synthesis as expected; whereas positively charged graphene oxides can only interact with Ru precursors via Van der Waals forces, resulting in a significant agglomeration of metallic ruthenium nanoparticles and thus a low catalytic performance. Graphical Abstract: The morphology and oxidation state of ruthenium nanocrystallites supported on graphene substrate, thus the catalytic activity for ammonia synthesis, can be tailored by tuning the zeta potential of graphene oxide dispersed in polyols. [ABSTRACT FROM AUTHOR]

[Display omitted] • Porous graphitized carbon fiber (PGCF) is prepared from activated carbon fiber. • PGCF has enhanced hydrophobicity and can effectively remove VOCs from humid air. • Toluene-adsorbed PGCF is easily regenerated by low-temperature thermal desorption. Activated carbon fibers (ACFs) are a popular class of adsorbents for volatile organic compounds (VOCs), however, their abundant hydrophilic functional groups greatly limit their selective adsorption capacity for organics under humid conditions. In this work, porous graphitized carbon fibers (PGCFs) with enhanced hydrophobicity were prepared by KOH-promoted catalytic graphitization of viscose-based ACF, and their adsorption capacity for representative VOCs was investigated. Characterizations showed that the PGCFs had reduced O/C ratios, high specific surface areas exceeding 2200 m2/g, and micro-mesoporous structure. Under dry conditions, the adsorption capacity of a typical PGCF for toluene, cyclohexane and ethanol reached 7.2, 4.6 and 2.0 mmol/g, respectively. At 80 % relative humidity, the adsorption capacity for toluene and cyclohexane retained 92 % and 85 %, respectively, while that for ethanol even increased by 54 %. The abundant π electrons and high polarizability of the PGCF strengthened the π-π interaction and dispersion force with non-polar organics, thereby enhancing their removal. The capillary condensed water in mesopores could act as absorbate for the uptake of polar ethanol under humid conditions. The toluene-adsorbed PGCF was effectively regenerated at a low temperature of 80 °C. Benefiting from their excellent adsorption capacity and moisture-resistance, PGCFs may be promising adsorbents to remove VOCs from air. [ABSTRACT FROM AUTHOR]

Vanadium slag (V-slag) is an important secondary V source, but other valuable elements are discarded in the tailings in industry. Herein, a green nitridation–corrosion process is proposed for the comprehensive recovery of valuable elements (V, Ti, Cr, Fe) from V-slag without producing hazardous waste. Thermodynamic results indicate that ammonia gas (NH 3) can selectively reduce Fe and nitride V, Cr, and Ti. The main phase composition of the nitrided V-slag included metallic Fe, nitrides, and diopside under optimal conditions, and their relative contents were 42.5, 26.2, and 31.3%, respectively, after roasting at 1000 °C for 6 h. The effects of the main parameters on corrosion test were investigated, and the highest weight-gain ratio attained was 19.6%. FeOOH crystallizes on the surface of the nitrided V-slag due to the oxidization of metallic Fe. The phase evolution during the entire process is spinel/olivine/diopside → Fe/nitrides/diopside → FeOOH/nitrides/diopside. Owing to finer particle sizes, most FeOOH is separated by wet sieving (<1400 mesh). The purity of the enriched nitrides attained was 43% after pickling to remove excess Fe. The total recovery rates of Fe, V, Ti, Cr were 87.76%, 95.92%, 92.92%, 92.11%, respectively. This paper provides a sustainable strategy for the comprehensive utilization of V-slag, and guides the cleaner treatment of other similar minerals. [Display omitted] • The NH 3 -based nitridation–corrosion process to recover V, Ti, Cr, and Fe from V-slag is proposed. • The reaction mechanism of reduction–nitridation process is revealed. • The optimal parameters during the nitridation–corrosion processes are investigated. • Enrichment of V, Ti, Cr nitrides and separation of Fe are realized. [ABSTRACT FROM AUTHOR]

In this paper, the low–temperature disintegration behavior of vanadium titanomagnetite (VTM) pellets in H 2 –CO–CO 2 –N 2 mixtures was investigated. Thermodynamic calculations indicated that pseudobrookite (Fe 2 TiO 5) was reduced in the order Fe 2 TiO 5 → Fe 2 TiO 4 → FeTiO 3 → FeTi 2 O 5 , and the reduction potentials of H 2 and CO were mainly depended on the temperature. The experiments were carried out at temperatures of 400–700 °C with H 2 /(H 2 + CO) of 0–1. The experimental results revealed that disintegration mainly occurred over the temperature range of 500–600 °C, because hematite/pseudobrookite was reduced to magnetite/titanomagnetite resulted in the lattice expansion. A maximum RDI −3.15mm of 45.30% was obtained at 550 °C with a H 2 /(H 2 + CO) ratio of 0.26, and the corresponding reduction degree was 13.31%. Moreover, cracks were observed with a H 2 /(H 2 + CO) ratio of 0.20. A certain interaction between H 2 and CO reduction exists, owing to their different diffusion coefficients and reduction potentials. The reduction by individual CO gases tended to follow the topochemical reaction mode, whereas the non-topochemical reaction mode was dominant with H 2 –CO mixtures. [Display omitted] • Thermodynamically, the reduction of pseudobrookite (Fe2TiO5) by H2 and CO is studied. • The disintegration behavior under different conditions is investigated. • The effect of different parameters on disintegration is obtained, and the reason is revealed. • The reaction modes named topochemical and non–topochemical under different gas mixtures are discussed. [ABSTRACT FROM AUTHOR]

Wet scrubbing is a low-cost process for disposing of air pollutants. Nevertheless, this method is rarely used for the treatment of volatile organic compounds (VOCs) because of their poor water solubility. In this study, we used a unique wet scrubbing system containing H 2 O 2 and activated carbon (AC)-supported iron oxychloride (FeOCl) nanoparticles to remove airborne dichloroethane (DCE). The operating conditions of the wet scrubber were optimized, and the mechanism was explored. The results showed that the adsorption of dissolved DCE onto AC promoted its transfer from air to water, while the accumulation of DCE on AC facilitated its oxidation by •OH generated on FeOCl catalyst. The wet scrubber performed well at pH 3 and low H 2 O 2 concentrations. By pulsed or continuous dosing H 2 O 2 , the cooperative adsorption-catalytic oxidation allowed long-term DCE removal from air. Benefiting from satisfactory cost-effectiveness, avoidance of toxic byproduct formation, and less corrosion and catalyst poisoning, wet scrubbers coupled with cooperative adsorption and heterogeneous advanced oxidation processes could have broad application potentials in VOC control. [Display omitted] • FeOCl/AC was prepared by a facile calcination method. • Wet scrubber containing H 2 O 2 and FeOCl/AC was effective in dichloroethane removal. • Intermittent or continuous dosing H 2 O 2 allowed long-term VOC removal from air. • Adsorption and catalytic oxidation cooperated in the wet scrubbing process. [ABSTRACT FROM AUTHOR]

Fe-based cermets are of considerable research interest owing to their excellent physical and mechanical properties. In this study, a new process for the reduction and nitridation of Panzhihua ilmenite using NH 3 was proposed to prepare Fe-TiN composites, and the process was deemed feasible by thermodynamic calculations. The final products, Fe and TiN, could be formed based on the reaction conditions. The experimental results validated that metallic Fe could be easily formed, while MgTiO 3 was more difficult to reduce than FeTiO 3. The final products of Fe/TiN/MgO obtained at 1373–1473 K were consistent with those from the thermodynamic analysis. By increasing the reduction temperature or duration, the Fe particles increased in size and mixed with the TiN particles. The elemental content of Mg, Al, and Ca in the magnetic product was 5.85 wt% after magnetic separation. A Fe-TiN cermet was prepared from the magnetic product by hot-pressing (HP) sintering. Fe and TiN were uniformly distributed in the cermet, and the hardness of the obtained cermet reached 18.2 GPa. This work could offer a new approach to the preparation of Fe-based cermets from low-grade ilmenite. [Display omitted] • A novel method for synthesizing Fe–TiN composites from low–grade ilmenite is proposed. • Clean ammonia gas is used as reduction and nitridation agent. • The phase transformation and microstructure evolution of ilmenite during the reduction roasting process are studied. • The Fe–TiN cermet with a hardness of 18.2GPa is prepared by hot pressing (HP) sintering. [ABSTRACT FROM AUTHOR]