MECHANICAL REDUCTION OF CuO BY Mg AT ROOM TEMPERATURE

The mechanical reduction of CuO by pure metallic Mg has been investigated during pulver- izing in ball mill at room temperature.The reduction was towards its completion of an average particle size down to 20 nm after milling for 32 h.The mechanism of the mechanical reduction of oxides seems to be the surface activation of nano-metre sized particles driven by mechani- cal force.

Characterization and Microstructure of PLZT RAINBOW Ceramics

A new type of large-displacement actuating materials called RAINBOW (Reduced and Internally Biased Oxide Wafer) ceramics is fabricated by a chemical reduction of PLZT piezoelectric ceramics. It is found that PLZT is easily reduced and the thickness of reduced layer has a linear relationship with the reduction time. The optimal conditions for producing RAINBOW samples from PLZT are determined to be 950℃ for 1-1.5 hours. SEM micrograph shows that the RAINBOW ceramics are composed of reduced and unreduced layer obviously. And the reduced layer is transgranularly fractured while the unreduced ceramic is intergranularly fractured. Metallic lead and refractor oxides (PbO, ZrO_2, ZrTiO_4, etc.) are found in the reduced layer by XRD analyses, however, the crystal structure of PLZT is not found. The analysis of the reduction mechanism is in good accordance with experimental data.

Dechlorination of carbon tetrachloride by the catalyzed Fe-Cu process

The dectrochemical reduction characteristics of carbon tetrachlofide （CT） were investigated using cyclic voltammetry in this study. In addition, the difference in reduction mechanisms of CT between Master Builders＇ iron and the catalyzed Fe-Cu process was discussed. The results showed that CT was reduced directly on the surface of copper rather than by atomic hydrogen produced at the cathode in the catalyzed Fe-Cu process. The reduction was realized largely by atomic hydrogen in Master Builders＇ iron. The entire CT in 350 ml aqueous solution with 320 mg/L was reduced to trichloromethane and dichloromethane in 2.25 h when 100 g of scrap iron with Fe/Cu ratio of 10：1 （w/w） were used. Moreover, the reduction rate slowed with time. CT could be reduced at acidic, neutral and alkaline pH from solution by Fe-Cu bimetallic media, but the mechanisms were different. The degradation rate was not significantly influenced by pH in the catalyzed Fe-Cu process; in Master Builders＇ iron it clearly increased with decreasing pH. The kinetics of the reductions followed pseudo-first order in both cases. Furthermore, the reductions under acidic conditions proceeded faster than that under the neutral and alkaline conditions. The catalyzed Fe-Cu process was superior to Master Builders＇ iron in treating CT-containing water and this advantage was particularly noticeable under alkaline conditions. The reduction was investigated in the cathode （Cu） and anode （Fe） compartments respectively, the results showed that the direct reduction pathway played an important role in the reduction by the catalyzed Fe-Cu process. The catalyzed Fe-Cu process is of practical value.

The Mechanism of Drag Reduction around Bodies of Revolution Using Bionic Non-Smooth Surfaces

Bionic non-smooth surfaces （BNSS） can reduce drag. Much attention has been paid to the mechanism of shear stress reduction by riblets. The mechanism of pressure force reduction by bionic non-smooth surfaces on bodies of revolution has not been well investigated. In this work CFD simulation has revealed the mechanism of drag reduction by BNSS, which may work in three ways. First, BNSS on bodies of revolution may lower the surface velocity of the medium, which prevents the sudden speed up of air on the cross section. So the bottom pressure of the model would not be disturbed sharply, resulting in less energy loss and drag reduction. Second, the magnitude of vorticity induced by the bionic model becomes smaller because, due to the sculpturing, the growth of tiny air bubbles is avoided. Thus the large moment of inertia induced by large air bubble is reduced. The reduction of the vorticity could reduce the dissipation of the eddy. So the pressure force could also be reduced. Third, the thickness of the momentum layer on the model becomes less which, according to the relationship between the drag coefficient and the momentum thickness, reduces drag.

Reduction of nitrobenzene by the catalyzed Fe/Cu process

The polarization behavior of the couple Fe/Cu in 100 mg/L nitrobenzene aqueous solution was studied using Evans coupling diagrams.The results indicated that the iron corrosion was limited by both anodic and cathodic half-cell reactions under the neutral conditions,and cathodically controlled under the alkaline conditions.Batch experiments were performed to study the effect of solution pH,reaction duration,concentration,type of electrolyte,and dissolved oxygen(DO)on the reduction of nitrobenzene by the catal...

Electrochemical reduction characteristics and mechanism of nitrobenzene compounds in the catalyzed Fe-Cu process

The reduction of the nitrobenzene compounds （NBCs） by the catalyzed Fe-Cu process and the relationship between the electrochemical reduction characteristics of NBCs at copper electrode and reduction rate were studied in alkaline medium（pH=11）. The catalyzed Fe-Cu process was found more effective on degradation of NBCs compared to Master Builder＇s iron. The reduction rate by the catalyzed Fe-Cu process decreased in the following order： nitrobenzene 〉4-chloro-nitrobenzene ≥m-dinitrobenzene ：〉 4-nitrophenol ≥2,4-dinitrotoluene 〉2-nitrophenol. The reduction rate by Master Builder＇s iron decreased in the following order： m-dinitrobenzene ≥4-chloro-nitrobenzene 〉4-nitrophenol 〉2,4-dinitrotoluene ≈nitrobenzene 〉2-nitrophenol. NBCs were reduced directly on the surface of copper rather than by the hydrogen produced at cathode in the catalyzed Fe-Cu process. The reduction was realized by the hydrogen produced at cathode and Fe（OH）2 in Master Builder＇s iron, It is an essential difference in reaction mechanisms between these two technologies. For this reason, the reduction by the catalyzed Fe-Cu depended greatly on NBC＇s electron withdrawing ability.

Phosphorus reduction behavior of high-phosphate iron ore during hydrogen-rich sintering

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).

Electrochemical behavior of tungsten in(NaCl–KCl–NaF–WO_3)molten salt

Abstract The electrochemical reaction mechanism and electrocrystaUization process of tungsten in the NaCl- KCl-NaF-WO3 molten salt were investigated at 973 K （700℃） by means of cyclic voltammetry, chronopotentiometry, and chronoamperometry techniques. The results show that the electrochemical reaction process of tungsten in the NaCl-KCl-NaF-WO3 molten salt system is a quasireversible process mix-controlled by ion diffusion rate and electron transport rate. Tungsten ion in this system is reduced to W（0） in two steps. The electrocrystallization process of tungsten is found to be an instantaneous, hemispheroid three-dimensional nucleation process and the tungsten ion diffusion coefficient of 2.361 × 10^-4 cm2.s^-1 is obtained at experimental conditions.

Reduction mechanism of high-chromium vanadium–titanium magnetite pellets by H_2–CO–CO_2 gas mixtures

The reduction of high-chromium vanadium–titanium magnetite as a typical titanomagnetite containing 0.95wt% V2O5 and 0.61wt% Cr2O3 by H2–CO–CO2 gas mixtures was investigated from 1223 to 1373 K. Both the reduction degree and reduction rate increase with increasing temperature and increasing hydrogen content. At a temperature of 1373 K, an H2/CO ratio of 5/2 by volume, and a reduction time of 40 min, the degree of reduction reaches 95%. The phase transformation during reduction is hypothesized to proceed as follows： Fe2O3 → Fe3O4 → FeO → Fe; Fe9 TiO 15 ＋ Fe2Ti3O9 → Fe2.75Ti0.25O4 → FeT iO 3 → TiO 2;（Cr0.15V0.85）2O3 → Fe2VO4; and Cr1.3Fe0.7O3 → FeC r2O4. The reduction is controlled by the mixed internal diffusion and interfacial reaction at the initial stage; however, the interfacial reaction is dominant. As the reduction proceeds, the internal diffusion becomes the controlling step.

Production of High Carbon Ferrochromium Using Melt Circulation

Some fundamental studies related to the production of high carbon ferrochromium were summarizedusing melt circulation technology carried out in the School of Chemical Engineering at the University of Birmingham. These studies focused on the kinetics of chromite reduction in Fe-C(-Cr-Si) melts. The effects of feed mode,fluxes, amount and particle size of reductant, particle size of chromite, melt composition and the reduction temperature were investigated. The reduction mechanisms were discussed. The results showed that (1 ) the reduction rates ofsintered chromite Pellets and non-compacted chromite powder in Fe-C(-Cr-Si) melts was generally very low,(2) addition of carbon in the non-compacted chromite feed greatly improved the reduction kinetics, (3) compaction of thecarbon-chromite mixtures into composite Pellets further improved the reduction kinetics and (4) addition of lime inthe composite Pellets increased the reduction rate, while the addition of silica may suppress the posihve effect oflime. It can be concluded that solid-state reduction, smelting reduction and dissolution proceed simultaneouslyduring the reduction of compacted compostite pellets or non-compacted composite mixtures in Fe-C(-Cr-Si) melts,and the early stage of reduction is very likely to be controlled by either or both solid-state and/or gas diffusionthrough the oxide phases and/or the product layers.

Reduction Mechanism of Scandium Ion in Fluoride Salt Melt

The electrochemical behavior of Sc^(3+) in LiF-NaF system was investigated. The cyclic voltammetry and chronopotentiometry were used to investigate the reduction mechanism of the electrochemical deposition of Sc^(3+) to Sc on Ag electrode in LiF-NaF system at 1043 K. Experimental results indicate that the electroreduction of Sc^(3+) to Sc is a reversible process with simple 3-electron transfer in one step controlled by diffusion.

Poverty reduction effects of integrating high-quality development and cultural tourism in China

The integration of the cultural tourism industry with high-quality development is believed to be an important method of alleviating poverty.Most research in this area has focused on single towns,cities,or regions without considering the spillover effects of neighboring areas.To fill this gap,this study applies a spatial panel econometric model to empirically test the spatial spillover effects of integrating the cultural tourism industry with high-quality developments and their mechanisms of poverty alleviation based on provincial panel data of the Chinese Mainland from 2010 to 2020.Four key results are presented.First,there is an obvious spatial dependence on the high-quality development scale,specialization level,and poverty level of cultural tourism integration.The common panel model is found to overestimate the impact of this integration on poverty alleviation because it ignores the spatial spillover-related explanatory variables.Second,the scale of development quality is found to have no significant impact on poverty alleviation when integrating cultural tourism;however,the level of development specialization has both a direct impact on poverty alleviation and the spatial spillover effect.Third,the integration of the cultural tourism industry in the Central and Western regions is shown to have a strong direct effect on poverty reduction through high-quality development.However,the spillover effect on poverty reduction in the Eastern region is greater than that in the Central and Western regions.Fourth,the integration of high-quality development and cultural tourism is found to have a direct impact on poverty alleviation overall by promoting tourism consumption,material capital accumulation,and structural transformation.

Influence of mechanical reduction amount on internal quality of continuous casting billets by thermal and numerical simulation

With establishment of thermal and numerical simulation models,the influence of reduction amount on solidification structure,segregation and shrinkage porosity of continuous casting(CC)billets was investigated.The thermal–mechanical coupled simulation results indicated that with an increase in reduction amount,the temperature in the central area decreases,and the reduction efficiency firstly increases and then decreases,reaching the maximum value at reduction amount of 6 mm.Metallographic analysis showed that increasing the reduction amount is beneficial for the refinement of central solidification structure.Moreover,the internal cracks are more likely to appear at higher reduction efficiency.The X-ray computerized tomography results revealed that a higher reduction amount can significantly reduce the volume fraction and equivalent diameter of the central shrinkage porosities of CC billets and increase the sphericity of them.Simultaneously,the macrosegregation of carbon along the central line is improved as the reduction amount increases;while the reduction amount exceeds 8 mm,the segregation degree will not change any more.

Study on the Yield Reduction Mechanism of Soybean Planted under Continuous and every Second Year Cropping Conditions

Three-year investigation was conducted to demonstrate the mechanism of reduction of soybean yield aroused by continuous and every second year cropping. Compared to normal cropping, there are many unfavorable changes in some major elements of soybean plant and soil environment. Chloropyll content was lower. Phosphorous content of soybean plant was decreased seriously. Potassium content was lower while calcium content was higher. Magnesium content was wot affected and decreased in susceptive varieties. Some deseases and insects of soybean under continuous and wery second year cropping conditions became serious as continuous years prolonged. Organic matter content tended to go down from normal rotation to continuous cropping. Amount of bacteria and antinomyces decreased while amount of fungi increased. The development of symbiotic nitrogen fixation system wsa deteriorated.

Efficient reduction and adsorption of Cr(Ⅵ)using FeCl_(3)-modified biochar:Synergistic roles of persistent free radicals and Fe(Ⅱ)

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 infuences 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 electrondonating 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.

Reduction behavior of iron ore powder by high-volatile coal in thermogravimetric-gas chromatographic and kinetic analysis

The reduction behavior of iron ore powder by high-volatile coal was investigated,and its kinetic mechanism was clarified.The effect of volatiles in coal on the reduction reaction of iron ore was compared by utilizing a Xinjiang lignite with a high volatile content and its pyrolysis carbon produced by high-temperature pyrolysis to remove volatiles,serving as a reductant.The mass loss and gas composition of the samples during the reduction process were detected using thermo-gravimetric analysis and gas chromatography,and the morphological changes of iron ore powder were observed through scanning electron microscopy.The kinetic parameters of the iron oxide reduction reaction were calculated by the Flynn-Ozawa-Wall method,and the kinetic mechanism of volatile participation in the iron oxide reduction reaction was determined through the Coats-Redfern method.The results indicate that the coupling effect between the high-volatile coal pyrolysis and reduction reactions occurs during the second stage of the entire coupling process,which corresponds to the late stage of coal pyrolysis with a substantial release of H_(2)and CO.The volatiles in coal actively participated in the reduction reaction,reducing the initiation temperature of the reaction by around 200℃.The reduction of iron oxides by high-volatile coal was jointly promoted by the"hydrogen cycle"and"carbon cycle",resulting in a higher reduction extent and metallization rate at the end of the reaction.When high-volatile coal was used as the reductant,the average activation energy for the entire process was 76.5 kJ/mol,a significant decrease compared to the employment of pyrolysis carbon without volatiles as the reductant(1167 kJ/mol).

Theoretical perspectives on the reduction of Pu(Ⅳ)and Np(Ⅵ)by methylhydrazine in HNO_(3)solution:Implications for Np/Pu separation

Effective adjustment and control of the oxidation state of plutonium(Pu)and neptunium(Np)is an indispensable component of Np/Pu separation in spent nuclear fuel reprocessing.Some hydrazine derivatives including methylhydrazine(CH_(3)N_(2)H_(3))effectively achieves the reduction of Np(Ⅵ)to Np(V)without reducing Pu(Ⅳ).Herein,we explored the reduction mechanisms of Pu(Ⅳ)and Np(Ⅵ)by CH_(3)N_(2)H_(3)in HNO_(3)solution using scalar-relativistic density functional theory.We elucidated the difference in the reduction mechanism between Np(Ⅵ)and Pu(Ⅳ)ions by CH_(3)N_(2)H_(3).The energy barrier for the reduction of[NpⅥO_(2)(H_(2)O)_(5)]^(2+)and[NpⅥO_(2)(NO_(3))(H_(2)O)_(3)]^(+)by CH_(3)N_(2)H_(3)is largely different due to the coordination of nitrate ion.Moreover,the energy barrier of the reduction of[NpⅥO_(2)(H_(2)O)_(5)]^(2+)is apparently lower than that of[PuⅣ(NO_(3))_(2)(H_(2)O)_(7)]^(2+),which is in line with the experimental observations.The results of Mayer bond order and localized molecular orbitals clarify the structural evolution of the reaction pathways.Analysis of the spin density demonstrates that the first Np(Ⅵ)and Pu(Ⅳ)reduction belongs to the outer-sphere electron transfer and the second Np(Ⅵ)and Pu(Ⅳ)reduction is the hydrogen transfer.This study explains theoretically why CH_(3)N_(2)H_(3)reduces Np(Ⅵ)but not Pu(Ⅳ),and helps to design promising reductants for the Np/Pu separation in spent nuclear fuel reprocessing.

A non-precious metal catalyst for oxygen reduction prepared by heat-treating a mechanical mixture of carbon black,melamine and cobalt chloride

A non-precious metal catalyst CoMe]C for the oxygen reduction reaction is prepared by heat-treating a mechanical mixture of carbon black, melamine and cobalt chloride at 600 under nitrogen atmosphere for 2 h. The catalytic activity of CoMe/C is characterized by the electrochemical linear sweep voltammetry technique. The onset reduction potential of the catalyst is 0.55 V （vs. SCE） at a scanning rate of 5 mV/s in 0.5 mol/L H2SO4 solution. The formation of the ORR activity sites of CoMe/C is facilitated by metallic β- cobalt.

Effects of Na_(2)CO_(3)on reduction mechanism and kinetics of iron during deep reduction of ilmenite concentrate

High-quality upgraded titanium slag obtained through semi-molten reduction with the addition of Na_(2)CO_(3)is important for the fluidizing chlorination process to produce TiO_(2)pigments.The key is the effect of Na_(2)CO_(3)on the reduction behavior of iron.Therefore,the effects of Na_(2)CO_(3)on reduction mechanism and kinetics of iron during deep reduction of ilmenite concentrate were studied.The results indicated that the metallization ratio of the reduced sample increased with increasing temperature,time,and dose of Na_(2)CO_(3).The addition of Na_(2)CO_(3)significantly accelerated the reduction of iron in the ilmenite concentrate and promoted the growth of iron particles.However,the addition of Na_(2)CO_(3)produced sodium iron titanates;thus,the metallization ratio of the sample decreased with an increase in the temperature and time when the temperature was above 1200℃and the time was more than 30 min.When the doses of Na_(2)CO_(3)were 0,3,and 6 wt.%,the reduction of iron was controlled by the interfacial chemical reaction,both the interfacial chemical reaction and diffusion,and diffusion,respectively,and the apparent activation energies were 134.91,64.89,and 120.82 kJ/mol,respectively.

NUMERICAL SIMULATION AND EXPERIMENTAL STUDY OF DRAGREDUCING SURFACE OF A REAL SHARK SKIN

It is well known that shark skin surface can effectively inhabit the occurrence of turbulence and reduce the wall friction, but in order to understand the mechanism of drag reduction, one has to solve the problem of the turbulent flow on grooved-scale surface, and in that respect, the direct numerical simulation is an important tool. In this article, based on the real biological shark skin, the model of real shark skin is built through high-accurate scanning and data processing. The turbulent flow on a real shark skin is comprehensively simulated, and based on the simulation, the drag reduction mechanism is discussed. In addition, in order to validate the drag-reducing effect of shark skin surface, actual experiments were carried out in water tunnel, and the experimental results are approximately consistent with the numerical simulation.