Lost circulation, a recurring peril during drilling operations, entails substantial loss of drilling fluid and dire consequences upon its infiltration into the formation. As drilling depth escalates, the formation tem...Lost circulation, a recurring peril during drilling operations, entails substantial loss of drilling fluid and dire consequences upon its infiltration into the formation. As drilling depth escalates, the formation temperature and pressure intensify, imposing exacting demands on plug materials. In this study, a kind of controllable curing resin with dense cross-network structure was prepared by the method of solution stepwise ring-opening polymerization. The resin plugging material investigated in this study is a continuous phase material that offers effortless injection, robust filling capabilities, exceptional retention, and underground curing or crosslinking with high strength. Its versatility is not constrained by fracture-cavity lose channels, making it suitable for fulfilling the essential needs of various fracture-cavity combinations when plugging fracture-cavity carbonate rocks. Notably, the curing duration can be fine-tuned within the span of 3-7 h, catering to the plugging of drilling fluid losing of diverse fracture dimensions. Experimental scrutiny encompassed the rheological properties and curing behavior of the resin plugging system, unraveling the intricacies of the curing process and establishing a cogent kinetic model. The experimental results show that the urea-formaldehyde resin plugging material has a tight chain or network structure. When the concentration of the urea-formaldehyde resin plugging system solution remains below 30%, the viscosity clocks in at a meager 10 mPa·s. Optimum curing transpires at 60℃, showcasing impressive resilience to saline conditions. Remarkably, when immersed in a composite saltwater environment containing 50000 mg/L NaCl and 100000 mg/L CaCl_(2), the urea-formaldehyde resin consolidates into an even more compact network structure, culminating in an outstanding compressive strength of 41.5 MPa. Through resolving the correlation between conversion and the apparent activation energy of the non-isothermal DSC curing reaction parameters, the study attests to the fulfillment of the kinetic equation for the urea-formaldehyde resin plugging system. This discerning analysis illuminates the nuanced shifts in the microscopic reaction mechanism of the urea-formaldehyde resin plugging system. Furthermore, the pressure bearing plugging capacity of the resin plugging system for fractures of different sizes is also studied. It is found that the resin plugging system can effectively resident in parallel and wedge-shaped fractures of different sizes, and form high-strength consolidation under certain temperature conditions. The maximum plugging pressure of resin plugging system for parallel fractures with outlet size 3 mm can reach 9.92 MPa, and the maximum plugging pressure for wedge-shaped fractures with outlet size 5 mm can reach 9.90 MPa. Consequently, the exploration and application of urea-formaldehyde resin plugging material precipitate a paradigm shift, proffering novel concepts and methodologies in resolving the practical quandaries afflicting drilling fluid plugging.展开更多
Based on the requirements of dual-carbon strategy and the major needs of sustainable development,it was of great significance to develop green and environmentally-friendly bio-based rubbers.However,it was difficult fo...Based on the requirements of dual-carbon strategy and the major needs of sustainable development,it was of great significance to develop green and environmentally-friendly bio-based rubbers.However,it was difficult for existing rubber materials to simultaneously meet the requirements of low-temperature resistance and excellent dynamic performance,which greatly limited its application in special fields at low temperature.To solve this problem,the bio-based acyclic sesquiterpene compound,trans-β-farnesene was autonomously synthesized by bio-fermentation in our laboratory.展开更多
Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment ...Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment of Ti_(3)C_(2)MXene under Ar/H_(2)S atmosphere to facilitate the hydrogen release and uptake from MgH_(2).The S-Ti_(3)C_(2)exhibited pleasant catalytic effect on the hydriding/dehydriding kinetics and cyclic stability of MgH_(2).The addition of 5 wt%S-Ti_(3)C_(2)into MgH_(2)resulted in a reduction of 114℃in the starting dehydriding temperature compared to pure MgH_(2).MgH_(2)+5 wt%S-Ti_(3)C_(2)sample could quickly release 6.6 wt%hydrogen in 17 min at 220℃,and 6.8 wt%H_(2)was absorbed in 25 min at 200℃.Cyclic testing revealed that MgH_(2)+5 wt%S-Ti_(3)C_(2)system achieved a reversible hydrogen capacity of 6.5 wt%.Characterization analysis demonstrated that Ti-species(Ti0,Ti^(2+),Ti-S,and Ti^(3+))as active species significantly lowered the dehydrogenation temperature and promoted the re-/dehydrogenation kinetics of MgH_(2),and sulfur doping can effectively improve the stability of Ti0 and Ti^(3+),contributing to the improvement of cyclic stability of MgH_(2).This study provides strategy for the construction of catalysts for hydrogen storage materials.展开更多
This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that ...This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without Co.Moreover,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to 0.6.The improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant pair.Furthermore,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant pair.These findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.展开更多
Hydrogen-enriched ironmaking presents a promising approach to mitigate coke consumption and carbon emission in blast furnace(BF)operations.This work investigated the relationship between the structural features of cok...Hydrogen-enriched ironmaking presents a promising approach to mitigate coke consumption and carbon emission in blast furnace(BF)operations.This work investigated the relationship between the structural features of cokes and their reactivity towards solution loss(SL),especially under hydrogen-enriched atmospheres.Six cokes were characterized,and their SL behaviors were examined under varying atmospheres to elucidate the effects of hydrogen enrichment.The results indicate that an increase in fixed carbon content leads to a decrease in the coke reactivity index(CRI)and an increase in coke strength after reaction(CSR),in the CO_(2) atmosphere,the CSR of coke increases from 35.76%−62.83%,while in the 90CO_(2)/10H_(2) atmosphere,the CSR of coke increases from 65.67%−84.09%.There is a good linear relationship between CRI and microcrystalline structure parameters of coke.Cokes with larger crystalline size,lower amorphous content,and smaller optical texture index(OTI)values show enhanced resistance to degradation and maintain structural integrity in BF.Kinetic analysis performed with the shifted-modified-random pore model(S-MRPM)reveals that alterations in pore structure and intrinsic mineral composition significantly influence the reaction rate.The introduction of a small amount of water vapor raises SL rates,whereas a minor addition of hydrogen(<10%)decelerates SL due to its incomplete conversion to water vapor and the reduced partial pressure of the gasifying agent.Thermodynamic calculations also indicate that the introduced hydrogen does not convert into the same fraction of water vapor.The shift from chemical reaction control to gas diffusion control as the rate-determining step with rising temperatures during SL process was confirmed,and the introduction of hydrogen does not notably alter SL behavior.This result demonstrated that introducing a small amount of hydrogen(<10%)can mitigate SL rates,thereby enhancing coke strength and reducing coke consumption and carbon emissions.展开更多
Hydrogen desorption kinetics and characteristics,residual hydrogen content and activation energy of TC21 alloy were investigated by the constant volume method.Results show that hydrogen desorption temperature and init...Hydrogen desorption kinetics and characteristics,residual hydrogen content and activation energy of TC21 alloy were investigated by the constant volume method.Results show that hydrogen desorption temperature and initial hydrogen pressure affect hydrogen desorption characteristics of TC21 alloy.The hydrogen desorption process is mainly dominated by nucleation and growth process(kt=[-ln(1-α)]^(2/3)),chemical reaction process(kt=(1-α)^(-1/2))and three-dimensional diffusion process(kt=[1-(1-α)^(1/3)]^(1/2))when the hydrogenated TC21 alloy is dehydrogenated at temperatures of 700-940°C.When the hydrogenated TC21 alloy releases hydrogen,the following relationship exists among the rate constants of each process:k(chemical reaction process)>k(nucleation and growth process)>k(three-dimensional diffusion process).The residual hydrogen content of the hydrogenated TC21 alloy after hydrogen desorption decreases gradually with the increase in hydrogen desorption temperature,and increases gradually with the increase in the initial hydrogen pressure.The activation energy of TC21 alloy in the process of hydrogen desorption is about 26.663 kJ/mol.展开更多
To overcome reliance on molds and the difficulty of fabricating complex geometries with traditional C/C composites,direct ink writing(DIW)with UV/heat dual curing was employed to produce high-performance C/C composite...To overcome reliance on molds and the difficulty of fabricating complex geometries with traditional C/C composites,direct ink writing(DIW)with UV/heat dual curing was employed to produce high-performance C/C composites.The rheological properties of the composite inks were systematically analyzed to assess the effects of phenolic resin(PR)and carbon fiber(CF)content.Results show pronounced shear-thinning behavior and strong thixotropy-both essential for stable DIW.Additionally,UV/heat curing behavior was characterized to provide theoretical insights for optimizing curing parameters.Notably,CF addition is found to significantly attenuate UV light penetration compared to pure PR.As CF content increases,the critical UV irradiation energy rises sharply from 68.47 to 911.19 mJ/cm^(2),necessitating precise adjustments to curing parameters.Preforms were pyrolyzed in a carbon tube furnace to examine pore-formation characteristics,and chemical vapor infiltration(CVI)was applied to filling the resulting pores,yielding C/C composites with a flexural strength of 115.19 MPa.展开更多
[2-(3,4-epoxy-cyclohexyl)ethyl]dimethyltert-butylsilane was synthesized,using tert-butyldimethylsilane(TBDMS)and 1,2-epoxy-4-vinylcyclohexane(EVC)as the main raw materials and tris(triphenylphosphine)chlororhodium(I)[...[2-(3,4-epoxy-cyclohexyl)ethyl]dimethyltert-butylsilane was synthesized,using tert-butyldimethylsilane(TBDMS)and 1,2-epoxy-4-vinylcyclohexane(EVC)as the main raw materials and tris(triphenylphosphine)chlororhodium(I)[RhCl(Ph3P)3]as the catalyst.[2-(3,4-epoxy-cyclohexyl)ethyl]dimethyltert-butylsilane is a novel kind of silicon-containing epoxide.The factors affecting the reaction yield,such as catalyst use,reaction time and reaction temperature,were investigated,and the synthesized product was characterized and analyzed by FT-IR and 1H-NMR.A series of amine-curing resins were prepared with[2-(3,4-epoxy-cyclohexyl)ethyl]dimethyltert-butylsilane,bisphenol A epoxy resin(E-51)and modified amine(593 amine).The mechanical properties of cured splines with the different proportions of amine-curing resins were tested.When the content of 593 amine was 20%,the content of E-51 was 75%and the amount of[2-(3,4-epoxy-cyclohexyl)ethyl]dimethyltert-butylsilane was 5%,the mechanical properties of the cured splines were the best with the tensile strength being 23.3 MPa,the elongation at break being 7.8%,and the Young's modulus being 421.3 MPa.展开更多
To address the negative impact of an internal curing agent on strength while preserving its ability to resist autogenous shrinkage,we investigated the incorporation of triethanolamine and triisopropanolamine as early-...To address the negative impact of an internal curing agent on strength while preserving its ability to resist autogenous shrinkage,we investigated the incorporation of triethanolamine and triisopropanolamine as early-strength components.These additives were combined with an internal curing agent to prepare a compound early-strength internal curing agent so as to investigate how compound early-strength internal curing agents affect the mechanical characteristics and volume stability of mortar.This was assessed using a battery of tests,including strength,autogenous shrinkage,internal relative humidity,mercury intrusion porosimetry,X-ray powder diffraction,and scanning electron microscopy.These results indicate that the compound early-strength internal curing agent effectively maintains the volume stability of the mortar without compromising its early mechanical properties.The compressive strength ratios of the mortar mixed with the compound early-strength internal curing agent were 109.45% at 3 days and 119% at 7 days,indicating significant improvement compared with the internal curing agent.Furthermore,the 7-day autogenous shrinkage rate of the mortar was-56.78μm/m.The proportion of hazardous-grade pores larger than 100 nm was reduced to 3.54%,and the pore distribution was uniform.This study introduces innovative ideas and methods for mitigating the adverse effects of internal curing agents on the early strength of mortar.展开更多
The size effects were experimentally investigated and the underlying mechanism was analyzed.The results reveal that,as the specimen size increases,the interconnectivity of macropores slightly decreases.This in turn co...The size effects were experimentally investigated and the underlying mechanism was analyzed.The results reveal that,as the specimen size increases,the interconnectivity of macropores slightly decreases.This in turn constrains the diffusion of CO_(2) and moisture in the specimens,resulting in an increase in the discrepancy between the internal and external carbonation degrees.An increase in cement paste thickness simultaneously decreases the quantity,average size,and interconnectivity of macropores,lowering the diffusion efficacy of CO_(2) and moisture and exacerbating the overall heterogeneity in carbonation.Moreover,the gradual blockage of macropores leads to the emergence of localized ‘occluded zones’ with much lower carbonation degree.The reduction in aggregate size significantly alters the average diameter and connectivity of macropores,leading to notable change to overall non-uniformity.This study provides insight into improving the CO_(2) curing effect of pervious concrete products and developing uniform curing methods.展开更多
Hexafluoropropylene oxide(HFPO)is a crucial fluorinated chemical mainly synthesized from hexafluoropropylene(HFP)through the oxidation of oxygen.However,the reaction network and kinetic characteristics are not fully u...Hexafluoropropylene oxide(HFPO)is a crucial fluorinated chemical mainly synthesized from hexafluoropropylene(HFP)through the oxidation of oxygen.However,the reaction network and kinetic characteristics are not fully understood yet,resulting in a lack of theoretical basis for synthesis process improvement.Here,the free radical reaction mechanism and complete reaction network involved in the noncatalytic oxidation of HFP to synthesize HFPO was explored by density functional theory.Transition state theory was employed to calculate the intrinsic reaction rate constants for elementary reactions.Based on theoretical reaction rate ratios,reaction pathways were selected,and a simplified reaction network was derived.It was found that byproducts were formed owing to the decomposition of HFPO and subsequent reactions with excessive oxygen while oxygen tended to participate more in the main reaction under oxygen-deficient conditions.The variations in reaction pathways occurring at different HFP/oxygen molar ratios was well elucidated by comparing with experimental data.This research establishes a robust theoretical foundation for optimizing and regulating the synthesis of HFPO.展开更多
Intuitively,the solvation structure featuring stronger interacted sheath in deep eutectic solution(DES)electrolyte would result in sluggish interfacial charge transfer and intense polarization,which obstructs its prac...Intuitively,the solvation structure featuring stronger interacted sheath in deep eutectic solution(DES)electrolyte would result in sluggish interfacial charge transfer and intense polarization,which obstructs its practical application in emerging Zn based batteries.Unexpectedly,here we discover a Zn‖organic battery with exceptional kinetics properties enabled by a hydrated DES electrolyte,which can render higher discharge capacity,smaller voltage polarization,and faster kinetics of charge transfer in comparison with conventional aqueous 3 M ZnCl_(2)electrolyte,though its viscosity is two orders of magnitude higher than the latter.The improved kinetics of charge transfer and ion diffusion is demonstrated to originate from the local electron structure regulation of cathode in hydrated DES electrolyte.Furthermore,the DES electrolyte has also been shown to restrict parasitic reaction associated with active water by preferential urea-molecular adsorption on Zn surface and stronger water trapping in solvation structure,giving rise to long-term stable dendrite-free Zn plating/stripping.This work provides a new rationale for understanding electrochemical behaviors of organic cathodes in DES electrolyte,which is conducive to the development of high-performance Zn‖organic batteries.展开更多
The erosion process and kinetics of PbTe particles in a selenium melt were investigated.The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical r...The erosion process and kinetics of PbTe particles in a selenium melt were investigated.The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical reaction at low temperatures(573,583,and 593 K),but the limiting step is controlled by boundary layer diffusion at high temperatures(603 and 613 K).The Se-and Te-atom diffusion in the product layer becomes unbalanced as the product layer thickens,with Kirkendall voids generating in the product layer accelerating PbTe particle erosion.After the PbTe impurities in the selenium melt evolve into PbSe and Te,Te is evenly distributed in the selenium melt owing to the solubility of Se and Te.This study serves to clarify the evolution behavior of PbTe impurities in the selenium melt and the reason that Te often occurs in Se.展开更多
Al_(2)O_(3)and MgO serve as the primary gangue components in sintered ores,and they are critical for the formation of CaO-Fe_(2)O_(3)-xAl_(2)O_(3)(wt%,C-F-xA)and CaO-Fe_(2)O_(3)-xM gO(wt%,C-F-xM)systems,respectively.I...Al_(2)O_(3)and MgO serve as the primary gangue components in sintered ores,and they are critical for the formation of CaO-Fe_(2)O_(3)-xAl_(2)O_(3)(wt%,C-F-xA)and CaO-Fe_(2)O_(3)-xM gO(wt%,C-F-xM)systems,respectively.In this study,a nonisothermal crystallization thermodynamics behavior of C-F-xA and C-F-xM systems was examined using differential scanning calorimetry,and a phase identification and microstructure analysis for C-F-xA and C-F-xM systems were carried out by X-ray diffraction and scanning electron microscopy.Results showed that in C-F-2A and C-F-2M systems,the increased cooling rates promoted the precipitation of CaFe_(2)O_(4)(CF)but inhibited the formation of Ca_(2)Fe_(2)O_(5)(C2F).In addition,C-F-2A system exhibited a lower theoretical initial crystallization temperature(1566 K)compared to the C-F system(1578 K).This temperature further decreases to 1554 K and 1528 K in the C-F-4A and C-F-8A systems,respectively.However,in C-F-xM system,the increased MgO content raised the crystallization temperature.This is because that the enhanced precipitation of MF(a spinel phase mainly comprised Fe_(3)O_(4)and MgFe_(2)O_(4))and C2F phases suppressed the CF precipitation reaction.In kinetic calculations,the Ozawa method revealed the apparent activation energies of the C-F-2A and C-F-2M systems.Malek's method revealed that the crystallization process in C-F-2A system initially followed a logarithmic law(lnαor lnα2),later transitioning to a reaction order law((1-α)-1or(1-α)^(-1/2),n=2/3)or the lnα2function of the exponential law.In C-F-2M system,it consistently followed the sequencef(α)=(1-α)^(2)(αis the crystallization conversion rate;n is the Avrami constant;?(α)is the differential equations for the model function of C_(2)F and CF crystallization processes).展开更多
Iron ore pellets,as one of the main charges of blast furnaces,have a greater impact on the CO_(2)emission reduction and stable operation of blast furnaces.The isothermal reduction behavior of the pellets obtained from...Iron ore pellets,as one of the main charges of blast furnaces,have a greater impact on the CO_(2)emission reduction and stable operation of blast furnaces.The isothermal reduction behavior of the pellets obtained from a Chinese steel plant was studied in the gas mixtures of CO and N_(2).The results showed the reduction process is divided into two stages.The reduction in the initial stage(time t≤40 min)is cooperatively controlled by internal diffusion and interface chemical reactions with the activation energy of 30.19 and 16.67 kJ/mol,respectively.The controlling step of the reduction in the final stage(t>40 min)is internal diffusion with the activation energy of 34.60 kJ/mol.The reduction process can be described by two equations obtained from kinetic calculations.The reduction degree can be predicted under different temperatures and time,and the predicted results showed an excellent correlation with the experimental results.The reduction mechanisms were confirmed by the analysis of the scanning electron microscope equipped with an energy dispersive spectrometer and optical microscope.展开更多
The selective semi-hydrogenation of phenylacetylene(PA)to styrene(ST)represents a critical industrial reaction,essential for producing polymer-grade styrene.Yet,achieving high selectivity at high conversions remains f...The selective semi-hydrogenation of phenylacetylene(PA)to styrene(ST)represents a critical industrial reaction,essential for producing polymer-grade styrene.Yet,achieving high selectivity at high conversions remains fundamentally challenging due to competing overhydrogenation.Here we report an atomic-scale approach for encapsulating ultrafine PtCu(Platinum,Copper)bimetallic nanoclusters(NCs)within the microporous TS-1 zeolite matrix through a ligand-as sis ted hydrothermal strategy.Remarkably,the as-synthesized PtCu@TS-1 catalyst exhibited an unprecedented turnover frequency(TOF)of 2006.7 h^(-1)and a superior styrene yield of 87.7%,significantly surpassing conventional Pt-based catalysts.Advanced characterization and in situ spectroscopy revealed that electron-rich Pt sites,induced by electron transfer from Cu in confined PtCu ensembles,substantially lower the activation barrier for hydrogen dissociation,accelerating selective hydrogenation.Moreover,the atomic confinement effect within the zeolite structure effectively modulates intermediate adsorption and accelerates product desorption,thus overcoming the selectivity-activity tradeoff.This study introduces a generalizable atomic-level catalyst design principle,highlighting the immense potential of quantum-sized bimetallic clusters within porous materials for precisely tuning reaction selectivity and activity.展开更多
Using solid waste as a substitute for conventional cement has become an important way to reduce carbon emissions.This paper attempted to utilize steel slag(SS)and fly ash(FA)as supplementary cementitious material by u...Using solid waste as a substitute for conventional cement has become an important way to reduce carbon emissions.This paper attempted to utilize steel slag(SS)and fly ash(FA)as supplementary cementitious material by utilizing CO_(2)mineralization curing technology.This study examined the dominant and interactive influences of the residual water/cement ratio,CO_(2)pressure,curing time,and SS content on the mechanical properties and CO_(2)uptake rate of CO_(2)mineralization curing SS-FA-Portland cement ternary paste specimens.Additionally,microstructural development was analyzed.The findings demonstrated that each factor significantly affected compressive strength and CO_(2)uptake rate,with factor interactions becoming more pronounced at higher SS dosages(>30%),lower residual water/cement ratios(0.1-0.15),and CO_(2)pressures of 0.1-0.3 MPa.Microscopic examinations revealed that mineralization primarily yielded CaCO_(3)and silica gel.The residual w/c ratio and SS content significantly influenced the CaCO_(3)content and crystallinity of the mineralization products.Post-mineralization curing,the percentage of pores larger than 50 nm significantly decreased,the proportion of harmless pores smaller than 20 nm increased,and pore structure improved.This study also found that using CO_(2)mineralization curing SS-FA-Portland cement solid waste concrete can significantly reduce the negative impact on the environment.展开更多
In this work,silicon-carbon hybrid materials were adopted as an example to illustrate the novel strategy to in situ construct heterostructure with adjustable microstructure.Based on the temperature-dependent thermodyn...In this work,silicon-carbon hybrid materials were adopted as an example to illustrate the novel strategy to in situ construct heterostructure with adjustable microstructure.Based on the temperature-dependent thermodynamics and kinetics of reaction between Si and C,the processes for Si nanocrystals growth and C decoration were coupled at different zones of plasma flame according to its temperature and velocity fields by theoretical modeling,aiming to intentionally suppress the formation of undesirable carbide,and enable adjusting the microstructure of each counterpart separately in transient process.As a result,well-controlled Si/C nanocomposites,including nanospheres and nanowires with core-shell structures,were achieved,and this continuous and in-flight route is also potential for large-scale production.Further investigation on the electrochemical properties highlights the advantage of as proposed strategy to efficiently construct heterostructures with superior performance for various applications.展开更多
Silicomanganese dust contains large amounts of valuables,such as Si and Mn,which can be used as raw materials for the smelting of silicomanganese.However,the direct addition of dust to the submerged arc furnace can in...Silicomanganese dust contains large amounts of valuables,such as Si and Mn,which can be used as raw materials for the smelting of silicomanganese.However,the direct addition of dust to the submerged arc furnace can influence the permeability of burden due to the fine particle size of dust,which results in incomplete reduction reactions during the smelting process.In this paper,silicomanganese dust,graphite powder,and other additives were pressed to form carbon-containing dust briquettes,and the self-reduction process of the dust briquettes was investigated through the isothermal thermogravimetric method with different carbon–oxygen (C/O) molar ratios,contents of fluxing agents,and reduction temperatures.Various reduction kinetic models for dust briquettes at different temperatures were established.The results show that the reaction fraction of the dust briquettes was about 90%at a C/O molar ratio of 1.2 with optimal reduction efficiency.The addition of CaF_(2)contributed to the decrease in the melting point and viscosity of dust briquettes,which increased their reduction rate.As the reduction temperature increased,the reduction rate of dust briquettes increased.The reduction reaction rate of dust briquettes was controlled through gas-phase diffusion.Meanwhile,their reduction process was analyzed kinetically,with the reaction time of 5 min as the dividing line.The apparent activation energies for the two diffusion stages were 56.10 and 100.52 kJ/mol,respectively.The kinetic equations are expressed as[1-(1-f)^(1/3)]^(2)=0.69e^(-56100/(RT))t and [1-(1-f)^(1/3)]^(2)=2.06e^(-100520/(RT))t.展开更多
Selenium distillation slag(SDS)is a high-value-added secondary resource with a high recovery value.This paper aims to investigate the leaching behavior and kinetics of selenium,tellurium,and copper in the SDS acid oxi...Selenium distillation slag(SDS)is a high-value-added secondary resource with a high recovery value.This paper aims to investigate the leaching behavior and kinetics of selenium,tellurium,and copper in the SDS acid oxidation leaching process with H_(2)SO_(4) and H_(2)O_(2).The experimental results showed that under the optimum conditions,the contents of selenium,tellurium,and copper in the SDS were reduced from 22.13 wt%,3.58 wt%,and 6.42 wt%to 3.06 wt%,0.27 wt%,and 0.33 wt%,respectively.Correspondingly,the recovery rates are 87.08%,97.15%and 99.7%.The leaching processes of selenium and tellurium were controlled by diffusion and chemical reactions,and the leaching behavior of copper was controlled by chemical reactions.Below 45℃,the activation energies for selenium,tellurium,and copper were found to be 26.47,62.18 and 19.67 kJ/mol,respectively.In addition,the contents of lead,silver and gold in the leaching residue are increased to 46.8 wt%,8.35 wt%and 0.27 wt%,respectively.These substances can be utilized as raw materials for the recovery of these valuable metals.Importantly,the entire process does not generate toxic or harmful waste,making it a green and environmentally friendly method for resource recovery.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant 52374023, 52288101)Taishan Scholar Young Expert (Grant tsqn202306117)。
文摘Lost circulation, a recurring peril during drilling operations, entails substantial loss of drilling fluid and dire consequences upon its infiltration into the formation. As drilling depth escalates, the formation temperature and pressure intensify, imposing exacting demands on plug materials. In this study, a kind of controllable curing resin with dense cross-network structure was prepared by the method of solution stepwise ring-opening polymerization. The resin plugging material investigated in this study is a continuous phase material that offers effortless injection, robust filling capabilities, exceptional retention, and underground curing or crosslinking with high strength. Its versatility is not constrained by fracture-cavity lose channels, making it suitable for fulfilling the essential needs of various fracture-cavity combinations when plugging fracture-cavity carbonate rocks. Notably, the curing duration can be fine-tuned within the span of 3-7 h, catering to the plugging of drilling fluid losing of diverse fracture dimensions. Experimental scrutiny encompassed the rheological properties and curing behavior of the resin plugging system, unraveling the intricacies of the curing process and establishing a cogent kinetic model. The experimental results show that the urea-formaldehyde resin plugging material has a tight chain or network structure. When the concentration of the urea-formaldehyde resin plugging system solution remains below 30%, the viscosity clocks in at a meager 10 mPa·s. Optimum curing transpires at 60℃, showcasing impressive resilience to saline conditions. Remarkably, when immersed in a composite saltwater environment containing 50000 mg/L NaCl and 100000 mg/L CaCl_(2), the urea-formaldehyde resin consolidates into an even more compact network structure, culminating in an outstanding compressive strength of 41.5 MPa. Through resolving the correlation between conversion and the apparent activation energy of the non-isothermal DSC curing reaction parameters, the study attests to the fulfillment of the kinetic equation for the urea-formaldehyde resin plugging system. This discerning analysis illuminates the nuanced shifts in the microscopic reaction mechanism of the urea-formaldehyde resin plugging system. Furthermore, the pressure bearing plugging capacity of the resin plugging system for fractures of different sizes is also studied. It is found that the resin plugging system can effectively resident in parallel and wedge-shaped fractures of different sizes, and form high-strength consolidation under certain temperature conditions. The maximum plugging pressure of resin plugging system for parallel fractures with outlet size 3 mm can reach 9.92 MPa, and the maximum plugging pressure for wedge-shaped fractures with outlet size 5 mm can reach 9.90 MPa. Consequently, the exploration and application of urea-formaldehyde resin plugging material precipitate a paradigm shift, proffering novel concepts and methodologies in resolving the practical quandaries afflicting drilling fluid plugging.
基金Supported by National Natural Science Foundation of China(52403096).
文摘Based on the requirements of dual-carbon strategy and the major needs of sustainable development,it was of great significance to develop green and environmentally-friendly bio-based rubbers.However,it was difficult for existing rubber materials to simultaneously meet the requirements of low-temperature resistance and excellent dynamic performance,which greatly limited its application in special fields at low temperature.To solve this problem,the bio-based acyclic sesquiterpene compound,trans-β-farnesene was autonomously synthesized by bio-fermentation in our laboratory.
基金supported by the National Natural Science Foundation of China(U22A20120,52071135,51871090,U1804135,and 52301269)the Natural Science Foundation of Hebei Province for Innovation Groups Program(C2022203003)Fundamental Research Funds for the Universities of Henan Province(NSFRF220201).
文摘Designing catalysts with high catalytic activity and stability is the key to achieve the commercial application of MgH_(2).Herein,the sulfur doped Ti_(3)C_(2)(S-Ti_(3)C_(2))was successfully prepared by heat treatment of Ti_(3)C_(2)MXene under Ar/H_(2)S atmosphere to facilitate the hydrogen release and uptake from MgH_(2).The S-Ti_(3)C_(2)exhibited pleasant catalytic effect on the hydriding/dehydriding kinetics and cyclic stability of MgH_(2).The addition of 5 wt%S-Ti_(3)C_(2)into MgH_(2)resulted in a reduction of 114℃in the starting dehydriding temperature compared to pure MgH_(2).MgH_(2)+5 wt%S-Ti_(3)C_(2)sample could quickly release 6.6 wt%hydrogen in 17 min at 220℃,and 6.8 wt%H_(2)was absorbed in 25 min at 200℃.Cyclic testing revealed that MgH_(2)+5 wt%S-Ti_(3)C_(2)system achieved a reversible hydrogen capacity of 6.5 wt%.Characterization analysis demonstrated that Ti-species(Ti0,Ti^(2+),Ti-S,and Ti^(3+))as active species significantly lowered the dehydrogenation temperature and promoted the re-/dehydrogenation kinetics of MgH_(2),and sulfur doping can effectively improve the stability of Ti0 and Ti^(3+),contributing to the improvement of cyclic stability of MgH_(2).This study provides strategy for the construction of catalysts for hydrogen storage materials.
基金supported by the National Natural Science Foundation of China(No.52271089)the financial support from the C hina Postdoctoral Science Foundation(No.2023M732192)。
文摘This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without Co.Moreover,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to 0.6.The improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant pair.Furthermore,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant pair.These findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.
基金supported by National Natural Science Foundation of China(22178002,22178001)Natural Science Foundation of Anhui Province(2308085Y19)Excellent Youth Research Project of Anhui Provincial Department of Education(2022AH030045).
文摘Hydrogen-enriched ironmaking presents a promising approach to mitigate coke consumption and carbon emission in blast furnace(BF)operations.This work investigated the relationship between the structural features of cokes and their reactivity towards solution loss(SL),especially under hydrogen-enriched atmospheres.Six cokes were characterized,and their SL behaviors were examined under varying atmospheres to elucidate the effects of hydrogen enrichment.The results indicate that an increase in fixed carbon content leads to a decrease in the coke reactivity index(CRI)and an increase in coke strength after reaction(CSR),in the CO_(2) atmosphere,the CSR of coke increases from 35.76%−62.83%,while in the 90CO_(2)/10H_(2) atmosphere,the CSR of coke increases from 65.67%−84.09%.There is a good linear relationship between CRI and microcrystalline structure parameters of coke.Cokes with larger crystalline size,lower amorphous content,and smaller optical texture index(OTI)values show enhanced resistance to degradation and maintain structural integrity in BF.Kinetic analysis performed with the shifted-modified-random pore model(S-MRPM)reveals that alterations in pore structure and intrinsic mineral composition significantly influence the reaction rate.The introduction of a small amount of water vapor raises SL rates,whereas a minor addition of hydrogen(<10%)decelerates SL due to its incomplete conversion to water vapor and the reduced partial pressure of the gasifying agent.Thermodynamic calculations also indicate that the introduced hydrogen does not convert into the same fraction of water vapor.The shift from chemical reaction control to gas diffusion control as the rate-determining step with rising temperatures during SL process was confirmed,and the introduction of hydrogen does not notably alter SL behavior.This result demonstrated that introducing a small amount of hydrogen(<10%)can mitigate SL rates,thereby enhancing coke strength and reducing coke consumption and carbon emissions.
基金National Natural Science Foundation of China(52275328,51875157)。
文摘Hydrogen desorption kinetics and characteristics,residual hydrogen content and activation energy of TC21 alloy were investigated by the constant volume method.Results show that hydrogen desorption temperature and initial hydrogen pressure affect hydrogen desorption characteristics of TC21 alloy.The hydrogen desorption process is mainly dominated by nucleation and growth process(kt=[-ln(1-α)]^(2/3)),chemical reaction process(kt=(1-α)^(-1/2))and three-dimensional diffusion process(kt=[1-(1-α)^(1/3)]^(1/2))when the hydrogenated TC21 alloy is dehydrogenated at temperatures of 700-940°C.When the hydrogenated TC21 alloy releases hydrogen,the following relationship exists among the rate constants of each process:k(chemical reaction process)>k(nucleation and growth process)>k(three-dimensional diffusion process).The residual hydrogen content of the hydrogenated TC21 alloy after hydrogen desorption decreases gradually with the increase in hydrogen desorption temperature,and increases gradually with the increase in the initial hydrogen pressure.The activation energy of TC21 alloy in the process of hydrogen desorption is about 26.663 kJ/mol.
基金supported by State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China.
文摘To overcome reliance on molds and the difficulty of fabricating complex geometries with traditional C/C composites,direct ink writing(DIW)with UV/heat dual curing was employed to produce high-performance C/C composites.The rheological properties of the composite inks were systematically analyzed to assess the effects of phenolic resin(PR)and carbon fiber(CF)content.Results show pronounced shear-thinning behavior and strong thixotropy-both essential for stable DIW.Additionally,UV/heat curing behavior was characterized to provide theoretical insights for optimizing curing parameters.Notably,CF addition is found to significantly attenuate UV light penetration compared to pure PR.As CF content increases,the critical UV irradiation energy rises sharply from 68.47 to 911.19 mJ/cm^(2),necessitating precise adjustments to curing parameters.Preforms were pyrolyzed in a carbon tube furnace to examine pore-formation characteristics,and chemical vapor infiltration(CVI)was applied to filling the resulting pores,yielding C/C composites with a flexural strength of 115.19 MPa.
基金Funded by the National Natural Science Foundation of China(No.21865017)。
文摘[2-(3,4-epoxy-cyclohexyl)ethyl]dimethyltert-butylsilane was synthesized,using tert-butyldimethylsilane(TBDMS)and 1,2-epoxy-4-vinylcyclohexane(EVC)as the main raw materials and tris(triphenylphosphine)chlororhodium(I)[RhCl(Ph3P)3]as the catalyst.[2-(3,4-epoxy-cyclohexyl)ethyl]dimethyltert-butylsilane is a novel kind of silicon-containing epoxide.The factors affecting the reaction yield,such as catalyst use,reaction time and reaction temperature,were investigated,and the synthesized product was characterized and analyzed by FT-IR and 1H-NMR.A series of amine-curing resins were prepared with[2-(3,4-epoxy-cyclohexyl)ethyl]dimethyltert-butylsilane,bisphenol A epoxy resin(E-51)and modified amine(593 amine).The mechanical properties of cured splines with the different proportions of amine-curing resins were tested.When the content of 593 amine was 20%,the content of E-51 was 75%and the amount of[2-(3,4-epoxy-cyclohexyl)ethyl]dimethyltert-butylsilane was 5%,the mechanical properties of the cured splines were the best with the tensile strength being 23.3 MPa,the elongation at break being 7.8%,and the Young's modulus being 421.3 MPa.
基金Funded by the Guangxi Key Research and Development Program(No.GK AB19259008)the Director's Fund of Key Laboratory of Non-ferrous Metals and Materials Processing New Technology of Ministry of Education(No.22AA-6)。
文摘To address the negative impact of an internal curing agent on strength while preserving its ability to resist autogenous shrinkage,we investigated the incorporation of triethanolamine and triisopropanolamine as early-strength components.These additives were combined with an internal curing agent to prepare a compound early-strength internal curing agent so as to investigate how compound early-strength internal curing agents affect the mechanical characteristics and volume stability of mortar.This was assessed using a battery of tests,including strength,autogenous shrinkage,internal relative humidity,mercury intrusion porosimetry,X-ray powder diffraction,and scanning electron microscopy.These results indicate that the compound early-strength internal curing agent effectively maintains the volume stability of the mortar without compromising its early mechanical properties.The compressive strength ratios of the mortar mixed with the compound early-strength internal curing agent were 109.45% at 3 days and 119% at 7 days,indicating significant improvement compared with the internal curing agent.Furthermore,the 7-day autogenous shrinkage rate of the mortar was-56.78μm/m.The proportion of hazardous-grade pores larger than 100 nm was reduced to 3.54%,and the pore distribution was uniform.This study introduces innovative ideas and methods for mitigating the adverse effects of internal curing agents on the early strength of mortar.
基金Funded by the National Natural Science Foundation of China (No.22203066)the 6th Young Elite Scientist Sponsorship Program by China Association for Science and Technology (No.2020QNRC001)。
文摘The size effects were experimentally investigated and the underlying mechanism was analyzed.The results reveal that,as the specimen size increases,the interconnectivity of macropores slightly decreases.This in turn constrains the diffusion of CO_(2) and moisture in the specimens,resulting in an increase in the discrepancy between the internal and external carbonation degrees.An increase in cement paste thickness simultaneously decreases the quantity,average size,and interconnectivity of macropores,lowering the diffusion efficacy of CO_(2) and moisture and exacerbating the overall heterogeneity in carbonation.Moreover,the gradual blockage of macropores leads to the emergence of localized ‘occluded zones’ with much lower carbonation degree.The reduction in aggregate size significantly alters the average diameter and connectivity of macropores,leading to notable change to overall non-uniformity.This study provides insight into improving the CO_(2) curing effect of pervious concrete products and developing uniform curing methods.
基金supported by the National Key Research&Development Program of China(2021YFB3803200)the National Natural Science Foundation of China(22288102).
文摘Hexafluoropropylene oxide(HFPO)is a crucial fluorinated chemical mainly synthesized from hexafluoropropylene(HFP)through the oxidation of oxygen.However,the reaction network and kinetic characteristics are not fully understood yet,resulting in a lack of theoretical basis for synthesis process improvement.Here,the free radical reaction mechanism and complete reaction network involved in the noncatalytic oxidation of HFP to synthesize HFPO was explored by density functional theory.Transition state theory was employed to calculate the intrinsic reaction rate constants for elementary reactions.Based on theoretical reaction rate ratios,reaction pathways were selected,and a simplified reaction network was derived.It was found that byproducts were formed owing to the decomposition of HFPO and subsequent reactions with excessive oxygen while oxygen tended to participate more in the main reaction under oxygen-deficient conditions.The variations in reaction pathways occurring at different HFP/oxygen molar ratios was well elucidated by comparing with experimental data.This research establishes a robust theoretical foundation for optimizing and regulating the synthesis of HFPO.
基金financial support from the National Natural Science Foundation of China(NSFC No.52202253,52072173)Natural Science Foundation of Jiangsu Province(No.BK20220914)+1 种基金Fundamental Research Funds for the Central Universities(No.ILA22061,ILA22075)Large Instrument and Equipment Sharing Fund of NUAA.
文摘Intuitively,the solvation structure featuring stronger interacted sheath in deep eutectic solution(DES)electrolyte would result in sluggish interfacial charge transfer and intense polarization,which obstructs its practical application in emerging Zn based batteries.Unexpectedly,here we discover a Zn‖organic battery with exceptional kinetics properties enabled by a hydrated DES electrolyte,which can render higher discharge capacity,smaller voltage polarization,and faster kinetics of charge transfer in comparison with conventional aqueous 3 M ZnCl_(2)electrolyte,though its viscosity is two orders of magnitude higher than the latter.The improved kinetics of charge transfer and ion diffusion is demonstrated to originate from the local electron structure regulation of cathode in hydrated DES electrolyte.Furthermore,the DES electrolyte has also been shown to restrict parasitic reaction associated with active water by preferential urea-molecular adsorption on Zn surface and stronger water trapping in solvation structure,giving rise to long-term stable dendrite-free Zn plating/stripping.This work provides a new rationale for understanding electrochemical behaviors of organic cathodes in DES electrolyte,which is conducive to the development of high-performance Zn‖organic batteries.
基金National Key Research and Development Program of China(No.2022YFC2904900)the National Natural Science Foundation of China(No.U1902221).
文摘The erosion process and kinetics of PbTe particles in a selenium melt were investigated.The results reveal that the limiting step of the reaction is controlled by product layer diffusion and the interfacial chemical reaction at low temperatures(573,583,and 593 K),but the limiting step is controlled by boundary layer diffusion at high temperatures(603 and 613 K).The Se-and Te-atom diffusion in the product layer becomes unbalanced as the product layer thickens,with Kirkendall voids generating in the product layer accelerating PbTe particle erosion.After the PbTe impurities in the selenium melt evolve into PbSe and Te,Te is evenly distributed in the selenium melt owing to the solubility of Se and Te.This study serves to clarify the evolution behavior of PbTe impurities in the selenium melt and the reason that Te often occurs in Se.
基金financially supported by the National Natural Science Foundation of China(Nos.52204331 and 52374315)the Major Industrial Innovation Plan of Anhui Provincial Development and the Reform Commission,China(No.AHZDCYCX-LSDT2023-01)。
文摘Al_(2)O_(3)and MgO serve as the primary gangue components in sintered ores,and they are critical for the formation of CaO-Fe_(2)O_(3)-xAl_(2)O_(3)(wt%,C-F-xA)and CaO-Fe_(2)O_(3)-xM gO(wt%,C-F-xM)systems,respectively.In this study,a nonisothermal crystallization thermodynamics behavior of C-F-xA and C-F-xM systems was examined using differential scanning calorimetry,and a phase identification and microstructure analysis for C-F-xA and C-F-xM systems were carried out by X-ray diffraction and scanning electron microscopy.Results showed that in C-F-2A and C-F-2M systems,the increased cooling rates promoted the precipitation of CaFe_(2)O_(4)(CF)but inhibited the formation of Ca_(2)Fe_(2)O_(5)(C2F).In addition,C-F-2A system exhibited a lower theoretical initial crystallization temperature(1566 K)compared to the C-F system(1578 K).This temperature further decreases to 1554 K and 1528 K in the C-F-4A and C-F-8A systems,respectively.However,in C-F-xM system,the increased MgO content raised the crystallization temperature.This is because that the enhanced precipitation of MF(a spinel phase mainly comprised Fe_(3)O_(4)and MgFe_(2)O_(4))and C2F phases suppressed the CF precipitation reaction.In kinetic calculations,the Ozawa method revealed the apparent activation energies of the C-F-2A and C-F-2M systems.Malek's method revealed that the crystallization process in C-F-2A system initially followed a logarithmic law(lnαor lnα2),later transitioning to a reaction order law((1-α)-1or(1-α)^(-1/2),n=2/3)or the lnα2function of the exponential law.In C-F-2M system,it consistently followed the sequencef(α)=(1-α)^(2)(αis the crystallization conversion rate;n is the Avrami constant;?(α)is the differential equations for the model function of C_(2)F and CF crystallization processes).
基金support from the National Natural Science Foundation of China(No.52174300)Natural Science Foundation of Chongqing,China(Nos.cstc2020jcyj-msxmX0583 and cstc2021jcyj-msxmX1004)+1 种基金Chongqing Talent Plan Project(No.cstc2021ycjh-bgzxm0211)Chongqing Doctoral"Through Train"Project(No.sl202100000343).T。
文摘Iron ore pellets,as one of the main charges of blast furnaces,have a greater impact on the CO_(2)emission reduction and stable operation of blast furnaces.The isothermal reduction behavior of the pellets obtained from a Chinese steel plant was studied in the gas mixtures of CO and N_(2).The results showed the reduction process is divided into two stages.The reduction in the initial stage(time t≤40 min)is cooperatively controlled by internal diffusion and interface chemical reactions with the activation energy of 30.19 and 16.67 kJ/mol,respectively.The controlling step of the reduction in the final stage(t>40 min)is internal diffusion with the activation energy of 34.60 kJ/mol.The reduction process can be described by two equations obtained from kinetic calculations.The reduction degree can be predicted under different temperatures and time,and the predicted results showed an excellent correlation with the experimental results.The reduction mechanisms were confirmed by the analysis of the scanning electron microscope equipped with an energy dispersive spectrometer and optical microscope.
基金financially supported by the Taishan Scholar Program of Shandong Province(No.tsqn202408211)China Postdoctoral Science Foundation(No.2024M761141)+3 种基金Postdoctoral Fellowship Program of CPSF(No.GZC20250785)Postdoctoral Innovation Program of Shandong Province(No.SDCX-ZG-202503085)Shandong Excellent YoungScientists Fund Program(No.2022HWYQ-082)National Natural Science Foundation of China(Nos.22278174,21808079,and 22378159)
文摘The selective semi-hydrogenation of phenylacetylene(PA)to styrene(ST)represents a critical industrial reaction,essential for producing polymer-grade styrene.Yet,achieving high selectivity at high conversions remains fundamentally challenging due to competing overhydrogenation.Here we report an atomic-scale approach for encapsulating ultrafine PtCu(Platinum,Copper)bimetallic nanoclusters(NCs)within the microporous TS-1 zeolite matrix through a ligand-as sis ted hydrothermal strategy.Remarkably,the as-synthesized PtCu@TS-1 catalyst exhibited an unprecedented turnover frequency(TOF)of 2006.7 h^(-1)and a superior styrene yield of 87.7%,significantly surpassing conventional Pt-based catalysts.Advanced characterization and in situ spectroscopy revealed that electron-rich Pt sites,induced by electron transfer from Cu in confined PtCu ensembles,substantially lower the activation barrier for hydrogen dissociation,accelerating selective hydrogenation.Moreover,the atomic confinement effect within the zeolite structure effectively modulates intermediate adsorption and accelerates product desorption,thus overcoming the selectivity-activity tradeoff.This study introduces a generalizable atomic-level catalyst design principle,highlighting the immense potential of quantum-sized bimetallic clusters within porous materials for precisely tuning reaction selectivity and activity.
基金Project(52479115)supported by the National Natural Science Foundation of ChinaProject(2024SF-YBXM-615)supported by the Key Research and Development Program of Shaanxi Province,China+1 种基金Project(2022943)supported by the Youth Innovation Team of Shaanxi Universities,ChinaProject(300102283721)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Using solid waste as a substitute for conventional cement has become an important way to reduce carbon emissions.This paper attempted to utilize steel slag(SS)and fly ash(FA)as supplementary cementitious material by utilizing CO_(2)mineralization curing technology.This study examined the dominant and interactive influences of the residual water/cement ratio,CO_(2)pressure,curing time,and SS content on the mechanical properties and CO_(2)uptake rate of CO_(2)mineralization curing SS-FA-Portland cement ternary paste specimens.Additionally,microstructural development was analyzed.The findings demonstrated that each factor significantly affected compressive strength and CO_(2)uptake rate,with factor interactions becoming more pronounced at higher SS dosages(>30%),lower residual water/cement ratios(0.1-0.15),and CO_(2)pressures of 0.1-0.3 MPa.Microscopic examinations revealed that mineralization primarily yielded CaCO_(3)and silica gel.The residual w/c ratio and SS content significantly influenced the CaCO_(3)content and crystallinity of the mineralization products.Post-mineralization curing,the percentage of pores larger than 50 nm significantly decreased,the proportion of harmless pores smaller than 20 nm increased,and pore structure improved.This study also found that using CO_(2)mineralization curing SS-FA-Portland cement solid waste concrete can significantly reduce the negative impact on the environment.
基金financially supported by the National Natural Science Foundation of China(No.52174342)Beijing Natural Sci-ence Foundation(No.2232044)Beijing Municipal Education Commission Research Plan General Project(No.KM202410005009).
文摘In this work,silicon-carbon hybrid materials were adopted as an example to illustrate the novel strategy to in situ construct heterostructure with adjustable microstructure.Based on the temperature-dependent thermodynamics and kinetics of reaction between Si and C,the processes for Si nanocrystals growth and C decoration were coupled at different zones of plasma flame according to its temperature and velocity fields by theoretical modeling,aiming to intentionally suppress the formation of undesirable carbide,and enable adjusting the microstructure of each counterpart separately in transient process.As a result,well-controlled Si/C nanocomposites,including nanospheres and nanowires with core-shell structures,were achieved,and this continuous and in-flight route is also potential for large-scale production.Further investigation on the electrochemical properties highlights the advantage of as proposed strategy to efficiently construct heterostructures with superior performance for various applications.
基金financially supported by the Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking (No. KF-20-3)Shandong Postdoctoral Science Foundation, China (No. SDCX-ZG-202301014)。
文摘Silicomanganese dust contains large amounts of valuables,such as Si and Mn,which can be used as raw materials for the smelting of silicomanganese.However,the direct addition of dust to the submerged arc furnace can influence the permeability of burden due to the fine particle size of dust,which results in incomplete reduction reactions during the smelting process.In this paper,silicomanganese dust,graphite powder,and other additives were pressed to form carbon-containing dust briquettes,and the self-reduction process of the dust briquettes was investigated through the isothermal thermogravimetric method with different carbon–oxygen (C/O) molar ratios,contents of fluxing agents,and reduction temperatures.Various reduction kinetic models for dust briquettes at different temperatures were established.The results show that the reaction fraction of the dust briquettes was about 90%at a C/O molar ratio of 1.2 with optimal reduction efficiency.The addition of CaF_(2)contributed to the decrease in the melting point and viscosity of dust briquettes,which increased their reduction rate.As the reduction temperature increased,the reduction rate of dust briquettes increased.The reduction reaction rate of dust briquettes was controlled through gas-phase diffusion.Meanwhile,their reduction process was analyzed kinetically,with the reaction time of 5 min as the dividing line.The apparent activation energies for the two diffusion stages were 56.10 and 100.52 kJ/mol,respectively.The kinetic equations are expressed as[1-(1-f)^(1/3)]^(2)=0.69e^(-56100/(RT))t and [1-(1-f)^(1/3)]^(2)=2.06e^(-100520/(RT))t.
基金Project(2022YFC2904900) supported by the National Key Research and Development Program of ChinaProject(U1902221) supported by the National Natural Science Foundation of China。
文摘Selenium distillation slag(SDS)is a high-value-added secondary resource with a high recovery value.This paper aims to investigate the leaching behavior and kinetics of selenium,tellurium,and copper in the SDS acid oxidation leaching process with H_(2)SO_(4) and H_(2)O_(2).The experimental results showed that under the optimum conditions,the contents of selenium,tellurium,and copper in the SDS were reduced from 22.13 wt%,3.58 wt%,and 6.42 wt%to 3.06 wt%,0.27 wt%,and 0.33 wt%,respectively.Correspondingly,the recovery rates are 87.08%,97.15%and 99.7%.The leaching processes of selenium and tellurium were controlled by diffusion and chemical reactions,and the leaching behavior of copper was controlled by chemical reactions.Below 45℃,the activation energies for selenium,tellurium,and copper were found to be 26.47,62.18 and 19.67 kJ/mol,respectively.In addition,the contents of lead,silver and gold in the leaching residue are increased to 46.8 wt%,8.35 wt%and 0.27 wt%,respectively.These substances can be utilized as raw materials for the recovery of these valuable metals.Importantly,the entire process does not generate toxic or harmful waste,making it a green and environmentally friendly method for resource recovery.
