In this study, the reaction characteristics of reduction of calcined dolomite with ferrosilicon under argon flow to produce magnesium were studied by conducting experiments Pidgeon pellets were used to study the effec...In this study, the reaction characteristics of reduction of calcined dolomite with ferrosilicon under argon flow to produce magnesium were studied by conducting experiments Pidgeon pellets were used to study the effect of reduced temperature, argon flow, and reduced time on the conversion of calcined dolomite reduction by ferrosilicon. The results show that the conversion significantly increases with the increase in the reduction temperature and reduction time. The conversion first increases and then decreases with the increase in argon flow. The highest conversion was obtained when the argon flow rate was 3 L·min^(-1), and a nearly spherical shape, nanoscale magnesium powder was obtained. Then the characters of the circulating argon entrainment process were numerically studied by ANSYS Fluent 17. A physical model of multilayer pellet arrangement was established, and a numerical calculation model of chemical reaction, radiation, heat conduction, and convection heat transfer was constructed. This confirms that high-temperature argon can effectively strengthen the heat exchange between pellets, improve the heat transfer efficiency, and facilitate the pellets to react quickly. When the conversion is 80%, the production efficiency increased by about 28.6%. In addition, the magnesium production efficiency showed an increase tendency with the increase of the argon inlet flow rate.展开更多
Spent cathode carbon(SCC)from aluminum electrolysis is a potential graphite resource.However,full use of the SCC remains a challenge,since it contains many hazardous substances(e.g.,fluoride salts,cyanides),encapsulat...Spent cathode carbon(SCC)from aluminum electrolysis is a potential graphite resource.However,full use of the SCC remains a challenge,since it contains many hazardous substances(e.g.,fluoride salts,cyanides),encapsulated within the thick carbon layers and thus posing serious environmental concerns.This work presents a chemical oxidative exfoliation route to achieve the recycling of SCC and the decontaminated SCC with high-valued graphene oxide(GO)-like carbon structures(SCC-GO)is applied as an excellent adsorbent for organic pollutants.Specifically,after the oxidative exfoliation,the embedded hazardous constituents are fully exposed,facilitating their subsequent removal by aqueous leaching.Moreover,benefiting from the enhanced specific surface areas along with abundant O-containing functional groups,the as-produced SCC-GO,shows an adsorption capacity as high as 347 mg·g^(-1)when considering methylene blue as a pollutant model,which exceeds most of the recently reported carbon-based adsorbents.Our study provides a feasible solution for the efficient recycling of hazardous carbonaceous wastes.展开更多
The properties of non-oxide materials are continuously revealed,and their applications in the fields of ceramics,energy,and catalysis are increasingly extensive.Regardless of the traditional binary materials or the MA...The properties of non-oxide materials are continuously revealed,and their applications in the fields of ceramics,energy,and catalysis are increasingly extensive.Regardless of the traditional binary materials or the MAX phases,the preparation methods,which are environmentally friendly,efficient,economical,and easy to scale-up,have always been the focus of attention.Molten salt synthesis has demonstrated unparalleled advantages in achieving non-oxide materials.In addition,with the development of the process in molten salt synthesis,it also shows great potential in scale-up production.In this review,the recent progress of molten salt synthesis in the preparation of binary non-oxide and MAX phase is reviewed,as well as some novel processes.The reaction mechanisms and the influence of synthetic conditions for certain materials are discussed in detail.The paper is finalized with the discussion of the application prospect and future research trends of molten salt synthesis in non-oxide materials.展开更多
The silicothermic reduction of magnesium was investigated by the non-isothermal thermoanalysis in flowing argon,while the traditional investigations of silicothermic process for magnesium reduction were carried out un...The silicothermic reduction of magnesium was investigated by the non-isothermal thermoanalysis in flowing argon,while the traditional investigations of silicothermic process for magnesium reduction were carried out under vacuum conditions.Firstly,the thermal gravimetric(TG)and derivative thermogravimetric(DTG)characteristic of briquettes prepared with calcined dolomite,ferrosilicon and fluorite were characterized by the thermogravimetric analyzer(TGA)at different heating rates.The intrinsic chemical kinetic mechanism was identified as a formal chemical reaction with the Nth order type which showed apparent activation energy E and reaction order n were 290.168 kJ mol^(-1) and 1.076,respectively.Then,a novel technique of magnesium production without vacuum was put forward and a three-dimensional unsteady numerical model incorporating the chemical reaction,radiation,heat conduction and heat convection was established and simulated,which was verified by Pidgeon process and novel tech no logy.rIhe nu merical results showed that the cycle time of the novel technique could be reduced when the argon temperature was higher than 1343 K and the argon entrance velocity was over 0.05 m s^(-1).And the effect of the argon temperature on reduction degree was much larger than that of entrance velocity.展开更多
Effect of the second phase in the micro-galvanic corrosion of a commercial Mg alloy containing rare earth elements, cast WE43 alloy,was investigated in 0.6 M NaCl solution and 0.6 M Na_(2)SO_(4)solution by scanning el...Effect of the second phase in the micro-galvanic corrosion of a commercial Mg alloy containing rare earth elements, cast WE43 alloy,was investigated in 0.6 M NaCl solution and 0.6 M Na_(2)SO_(4)solution by scanning electron microscopy(SEM) observations, scanning Kelvin probe force microscopy(SKPFM) analysis, hydrogen evolution, weight loss measurement, and electrochemical techniques. It is confirmed that the second phase of cast WE43 alloy is more active than Mg matrix and exhibits an anodic role in the micro-galvanic corrosion with α-Mg matrix as cathode and dissolves preferentially in Na_(2)SO_(4)solution, in contrast to the situation in NaCl solution. The corrosion rate of cast WE43 alloy in Na_(2)SO_(4)solution is much higher than that in NaCl solution, which is different from the conventional wisdom and could be attributed to the different role of the second phase in the micro-galvanic corrosion in two solutions.展开更多
The electrochemical behavior of Mg^(2+)and Al^(3+)in LiCl-KCl(mass 4:1)melt at 973 K was studied on a Mo electrode systematically by cyclic voltammetry,square wave voltammetry and chronopotentiometry.The results showe...The electrochemical behavior of Mg^(2+)and Al^(3+)in LiCl-KCl(mass 4:1)melt at 973 K was studied on a Mo electrode systematically by cyclic voltammetry,square wave voltammetry and chronopotentiometry.The results showed that the reductions of Mg^(2+)and Al^(3+)were reversible processes controlled by the rate of the mass transfer.When Mg^(2+)and Al^(3+)coexisted in LiCl-KCl melt,they had no significant effect on the reduction potential of each other.The equilibrium potentials of Mg^(2+)/Mg and Al^(3+)/Al were obtained by open circuit potential method.Their apparent standard potentials were also calculated in this system and the values were-2.52 V vs Cl_(2)/Cl^(−),-1.66 V vs Cl_(2)/Cl^(−),respectively.Correspondingly,the apparent Gibbs free energies of Mg^(2+)/Mg and Al^(3+)/Al were-485.71 kJ/mol^(-1),-480.78 kJ/mol^(-1).Finally,potentiostatic electrolysis was performed on a Mo electrode in LiCl-KCl-MgCl_(2)-AlCl_(3)(the mass ratio of MgCl_(2) to AlCl_(3) was 10:1)melt at different potentials.The components of the deposits were characterized by scanning electron microscope and energy dispersive spectroscopy.The study revealed that the content of Al in the deposit decreased as the overpotential increased and Al tended to segregate at the grain boundaries.展开更多
2-methyl-tetrahydrofuran(2-MTHF)is a promising biofuel or fuel additive with excellent burning property,a versatile new-style solvent in organic synthesis,and an important medical intermediate.In this work,a one-pot s...2-methyl-tetrahydrofuran(2-MTHF)is a promising biofuel or fuel additive with excellent burning property,a versatile new-style solvent in organic synthesis,and an important medical intermediate.In this work,a one-pot selective conversion of furfural(FA)into 2-MTHF was carried out over Zn doped Co/NC catalysts.The Zn-Co/NC-1 catalyst with trace Zn dopant(0.38 wt%)exhibited the best performance(yield of 2-MTHF:93.8%).According to the characterizations,it was found that the Zn not only incorporates into the carbon support but also partially dopes into Co nanoparticles.Subsequently,theoretical calculations demonstrated that the doping of Zn in carbon support can effectively enhance the electron transfer from the support to the metallic Co particle,leading to the electron-rich Co surface.The presence of Zn was found to promote the dissociation of hydrogen and to lower the diffusion barrier of hydrogen atom,in favor of the hydrogenation/hydrodeoxygenation processes.Furthermore,the Zn doped models exhibit much lower barrier in breaking C–OH bond of FOL,resulting in higher activity for hydrodeoxygenation of FOL.These theoretical results are consistent with the in situ FT-IR analysis of adsorption substrates and intermediates over Zn doped catalyst.This work reveals the mechanism of dopant Zn tailoring the electronic structure and catalytic performance of active sites,providing a deep insight into the design of economical and high-performance catalysts for hydrogenation/hydrodeoxygenation of biomass feedstocks.展开更多
The effects of fluoride ions(F^(-)) on the electrochemical behavior and coordination properties of titanium ions(Ti^(n+)) were studied in this work,by combining electrochemical and mathematical analysis as well as spe...The effects of fluoride ions(F^(-)) on the electrochemical behavior and coordination properties of titanium ions(Ti^(n+)) were studied in this work,by combining electrochemical and mathematical analysis as well as spectral techniques.The α was taken as a factor to indicate the molar concentration ratio of F^(-) and Ti^(n+).Cyclic voltammetry(CV),square wave voltammetry(SWV),and open circuit potential method(OCP)were used to study the electrochemical behavior of titanium ions under conditions of various α,and in-situ sampler was used to prepare molten salt samples when α equal to 0.0,1.0,2.0,3.0,4.0,5.0,6.0,and 8.0.And then,samples were analyzed by X-ray photoelectron spectroscopy(XPS) and Raman spectroscopy.The results showed that F^(-) in molten salt can reduce the reduction steps of titanium ions and greatly affects the proportion of valence titanium ions which making the high-valence titanium content increased and more stable.Ti^(2+) cannot be detected in the molten salt when α is higher than 3.0 and finally transferred to titanium ions with higher valence state.Investigation revealed that the mechanism behind those phenomenon is the coordination compounds(TiCl_(j) F_(i)^(m-)) forming.展开更多
Artificial cells are constructed from synthetic materials to imitate the biological functions of natural cells.By virtue of nanoengineering techniques,artificial cells with designed biomimetic functions provide altern...Artificial cells are constructed from synthetic materials to imitate the biological functions of natural cells.By virtue of nanoengineering techniques,artificial cells with designed biomimetic functions provide alternatives to natural cells,showing vast potential for biomedical applications.Especially in cancer treatment,the deficiency of immunoactive macrophages results in tumor progression and immune resistance.To overcome the limitation,a BaSO_(4)@ZIF-8/transferrin(TRF)nanomacrophage(NMΦ)is herein constructed as an alternative to immunoactive macrophages.Alike to natural immunoactive macrophages,NMΦis stably retained in tumors through the specific affinity of TRF to tumor cells.Zn^(2+)as an“artificial cytokine”is then released from the ZIF-8 layer of NMΦunder tumor microenvironment.Similar as proinflammatory cytokines,Zn^(2+)can trigger cell anoikis to expose tumor antigens,which are selectively captured by the BaSO_(4)cavities.Therefore,the hierarchical nanostructure of NMΦs allows them to mediate immunogenic death of tumor cells and subsequent antigen capture for T cell activation to fabricate long-term antitumor immunity.As a proof-of-concept,the NMΦmimics the biological functions of macrophage,including tumor residence,cytokine release,antigen capture and immune activation,which is hopeful to provide a paradigm for the design and biomedical applications of artificial cells.展开更多
Since solid-liquid interfacial nanobubbles(INBs)were first imaged,their long-term stability and large contact angle have been perplexing scientists.This study aimed to investigate the influence of internal gas density...Since solid-liquid interfacial nanobubbles(INBs)were first imaged,their long-term stability and large contact angle have been perplexing scientists.This study aimed to investigate the influence of internal gas density and external gas monolayers on the contact angle and stability of INB using molecular dynamics simulations.First,the contact angle of a water droplet was simulated at different nitrogen densities.The results showed that the contact angle increased sharply with an increase in nitrogen density,which was mainly caused by the decrease in solid-gas interfacial tension.However,when the nitrogen density reached 2.57 nm^(-3),an intervening gas monolayer(GML)was formed between the solid and water.After the formation of GML,the contact angle slightly increased with increasing gas density.The contact angle increased to 180°when the nitrogen density reached 11.38 nm^(-3),indicating that INBs transformed into a gas layer when they were too small.For substrates with different hydrophobicities,the contact angle after the formation of GML was always larger than 140°and it was weakly correlated with substrate hydrophobicity.The increase in contact angle with gas density represents the evolution of contact angle from macro-to nano-bubble,while the formation of GML may correspond to stable INBs.The potential of mean force curves demonstrated that the substrate with GML could attract gas molecules from a longer distance without the existence of a potential barrier compared with the bare substrate,indicating the potential of GML to act as a gas-collecting panel.Further research indicated that GML can function as a channel to transport gas molecules to INBs,which favors stability of INBs.This research may shed new light on the mechanisms underlying abnormal contact angle and long-term stability of INBs.展开更多
Spent catalyst used for denitration by selective catalytic reduction(spent SCR denitration catalysts) is one of the important urban mines due to the high content of TiO_(2)(~85 wt%) and the massive accumulation amount...Spent catalyst used for denitration by selective catalytic reduction(spent SCR denitration catalysts) is one of the important urban mines due to the high content of TiO_(2)(~85 wt%) and the massive accumulation amount(over 100,000 tons),therefore,value-added reutilization of titanium in spent SCR catalysts is considerably meaningful.In this paper,a novel method is proposed for converting the titanium oxide in spent SCR denitration catalysts to metallic titanium.Specifically,titanium dioxide(TiO_(2)) was firstly obtained from spent SCR denitration catalysts after removing the impurities by hydrometallurgy process.Then,TiO_(2) is converted to Ti_(2)CO by carbothermic reduction method,and Ti_(2)CO was further purified by oleic acid capture.Finally,by utilizing the as-prepared Ti_(2)CO as the consumable anode in the NaCl-KCl molten salt,high-purity metallic titanium was deposited at cathode,all confirming the feasibility for the conversion of low-grade TiO_(2) in the spent catalysts,from 60 wt% to high-purity metallic Ti(99.5 wt%), furthermore,the energy consumption of this process is 3950 kWh tonne-1 Ti,which is lower than that of most traditional titanium metallurgy methods.The method herein can provide new insights for the value-added recycling of titanium resources in urban mines.展开更多
Materialization of coal is one of effective and clean pathways for its utilization. The microstructures of coal-based carbon materials have an important influence on their functional applications. Herein, the microstr...Materialization of coal is one of effective and clean pathways for its utilization. The microstructures of coal-based carbon materials have an important influence on their functional applications. Herein, the microstructural evolution of anthracite in the temperature range of 1000–2800 ℃ was systematically investigated to provide a guidance for the microstructural regulation of coal-based carbon materials.The results indicate that the microstructure of anthracite undergoes an important change during carbonization-graphitization process. As the temperature increases, aromatic layers in anthracite gradually transform into disordered graphite microcrystals and further grow into ordered graphite microcrystals, and then ordered graphite microcrystals are laterally linked to form pseudo-graphite phase and eventually transformed into highly ordered graphite-like sheets. In particular, 2000–2200 ℃ is a critical temperature region for the qualitative change of ordered graphite crystallites to pseudo-graphite phase,in which the relevant structural parameters including stacking height, crystallite lateral size and graphitization degree show a rapid increase. Moreover, both aromaticity and graphitization degree have a linear positive correlation with carbonization-graphitization temperature in a specific temperature range.Besides, after initial carbonization, some defect structures in anthracite such as aliphatic carbon and oxygen-containing functional groups are released in the form of gaseous low-molecular volatiles along with an increased pore structure, and the intermediates derived from minerals could facilitate the conversion of sp^(3) amorphous carbon to sp^(2) graphitic carbon. This work provides a valuable reference for the rational design of microstructure of coal-based carbon materials.展开更多
Safe, green and efficient industrial production has always been the pursuit of the chemical industry. Since thermal energy is the driving force for most of chemical reactions, an ideal reaction tank would have the cap...Safe, green and efficient industrial production has always been the pursuit of the chemical industry. Since thermal energy is the driving force for most of chemical reactions, an ideal reaction tank would have the capacity to automatically regulate heat conduction rate. In detail, this reaction tank should endow an ability that resists the heat loss when the reaction temperature is lower than the target, while accelerating the heat dissipation when the system is overheated. In this case, this smart reactor can not only minimize energy consumption but also reduce safety risks.Hollow structures are known to reduce heat conductivity. Particularly, the hollow structure with multishells can provide more interfaces and thus further inhibit heat transmission, which would be more favorable for heat isolation. Step forward, by coupling HoMSs with temperature-sensitive polymer, a smart heat isolation material has been fabricated in this work. It performs as a good heat isolator at a relatively lower temperature. A heat insulation effect of 6.5℃ can be achieved for the TSPU/3S–TiO_(2)HoMSs with a thickness of 1 mm under the temperature field of 50℃.The thermal conductivity of composite material would be raised under overheating conditions. Furthermore, this composite displays an unusual two-stage phase transformation during heating. Benefiting from the unique multishelled structure, energy is found to be gradually guided into the hollow structure and stored inside. This localized heat accumulation enables the composite to be a potential coating material for intelligent thermal-regulator and site-defined micro-reactor.展开更多
The structural and electronic properties of bastnaesite were studied by using the first-principles method based on the density functional theory(DFT).The geometry structure of bastnaesite was first optimized,and then ...The structural and electronic properties of bastnaesite were studied by using the first-principles method based on the density functional theory(DFT).The geometry structure of bastnaesite was first optimized,and then the Mulliken populations,electron density and density of states were calculated and further analyzed in detail.The calculation results reveal that it mainly ruptures along the ionic Ce-O and Ce-F bonds during the cleavage of bastnaesite,leaving≡Ce^+,≡F^-and≡CO3^-dangling bonds exposed on the cleavage surface of bastnaesite.Combined with contact angle measurement,surface complexation theory and XPS analysis,the implications of structural and electronic properties on bastnaesite flotation reactions were studied.The hydration of exposed strong ionic bond on cleavage surface results in hydrophilic surface.According to surface complexation theory,the formed surface groups are≡CeOH^0,≡CO3 H^0 and≡FH^0 groups.The investigated metal ions and flotation reagents complex with surface≡CeOH^0 groups,while≡CO3H^0 and≡FH^0 groups are not involved in the complexation.The high activity of Ce atoms facilitates these surface reactions.展开更多
Graphdiyne(GDY)has the unique feature in the topological ordered arranged sp-and sp^(2)-hybridized carbon atoms,thus deriving a series of 2D allotropes.Due to inhomogeneousπ-bonding and carbon orbital overlap between...Graphdiyne(GDY)has the unique feature in the topological ordered arranged sp-and sp^(2)-hybridized carbon atoms,thus deriving a series of 2D allotropes.Due to inhomogeneousπ-bonding and carbon orbital overlap between different hybrid carbon atoms,GDY possesses a natural band gap with a Dirac cones structure.And GDY exhibits semiconductor property with a conductivity of 2.516×10^(−4) S/m at room temperature.The topological distribution of alkyne and benzene bonds of GDY makes its surface charge distribution extremely uneven,which produces high intrinsic activity for further modification.Its unique molecular structure endows the specific interaction with various species,such as ions,atoms,molecules and nanoparticles,showing excellent charge transport capability and unique advantages in mass transfer and energy conversion.From the view of the interaction principle between GDY and different compositions,we summarized the application of GDY-based materials in the fields of catalysis,energy conversion and storage,biological detection and so on.展开更多
In traditional ceramic processing techniques,high sintering temperature is necessary to achieve fully dense microstructures.But it can cause various problems including warpage,overfiring,element evaporation,and polymo...In traditional ceramic processing techniques,high sintering temperature is necessary to achieve fully dense microstructures.But it can cause various problems including warpage,overfiring,element evaporation,and polymorphic transformation.To overcome these drawbacks,a novel processing technique called“tcold sintering process(CSP)”has been explored by Randall et al.CSP enables densification of ceramics at ultra-low temperature(<300℃)with the assistance o f transient aqueous solution and applied pressure.In CSP,the processing conditions including aqueous solution,pressure,temperature,and sintering duration play critical roles in the densification and properties of ceramics,which will be reviewed.The review will also include the applications of CSP in solid-state rechargeable batteries.Finally,the perspectives about CSP is proposed.展开更多
Functional nanoparticles(NPs)with unique photoelectric,mechanical,magnetic,and chemical properties have attracted considerable attention.Aggregated NPs rather than individual NPs are generally required for sensing,ele...Functional nanoparticles(NPs)with unique photoelectric,mechanical,magnetic,and chemical properties have attracted considerable attention.Aggregated NPs rather than individual NPs are generally required for sensing,electronics,and catalysis.However,the transformation of functionalNPaggregates into scalable,controllable,and affordable functional devices remains challenging.Printing is a promising additive manufacturing technology for fabricating devices fromNPbuilding blocks because of its capabilities for rapid prototyping and versatile multifunctional manufacturing.This paper reviews recent advances in NP patterning based on the combination of self-assembly and printing technologies(including two-,three-,and four-dimensional printing),introduces the basic characteristics of these methods,and discusses various fields of NP patterning applications.展开更多
The effects of shear strength on aggregation flotation processes for fine spodumene(particle size less than 19μm)were investigated in this study.Sodium oleate was used as a surfactant and collector.The shear strength...The effects of shear strength on aggregation flotation processes for fine spodumene(particle size less than 19μm)were investigated in this study.Sodium oleate was used as a surfactant and collector.The shear strength was controlled by varying the agitation speed of a selfmade stirring apparatus.The aggregation process was studied by measuring the continuous transformations in the size distribution and shape of flocs.The results showed that as the shear strength increased,the distribution of fine spodumene transformed from bimodal to unimodal mode.The flocs tended to bridge more branches with a high shear strength and form globule-like flocs with very high strengths.The parameter"aggregation degree"was introduced to evaluate the aggregation process as a function of shear strength.The flotation rate of flocs formed with different shear strengths was also studied.These results demonstrated that the flotation rate was closely related to shear strength and that there was a close correlation between this and aggregation degree.These results could be used to guide the actual production of fine particles via shear aggregation flotation.展开更多
基金supported by Key Program of the National Natural Science Foundation of China (Grant No.92062223)the National Natural Science Foundation of China (Grant No.51804277)Anhui University Natural Science Research Project (KJ20190048)。
文摘In this study, the reaction characteristics of reduction of calcined dolomite with ferrosilicon under argon flow to produce magnesium were studied by conducting experiments Pidgeon pellets were used to study the effect of reduced temperature, argon flow, and reduced time on the conversion of calcined dolomite reduction by ferrosilicon. The results show that the conversion significantly increases with the increase in the reduction temperature and reduction time. The conversion first increases and then decreases with the increase in argon flow. The highest conversion was obtained when the argon flow rate was 3 L·min^(-1), and a nearly spherical shape, nanoscale magnesium powder was obtained. Then the characters of the circulating argon entrainment process were numerically studied by ANSYS Fluent 17. A physical model of multilayer pellet arrangement was established, and a numerical calculation model of chemical reaction, radiation, heat conduction, and convection heat transfer was constructed. This confirms that high-temperature argon can effectively strengthen the heat exchange between pellets, improve the heat transfer efficiency, and facilitate the pellets to react quickly. When the conversion is 80%, the production efficiency increased by about 28.6%. In addition, the magnesium production efficiency showed an increase tendency with the increase of the argon inlet flow rate.
基金supported by the National Natural Science Foundation of China(22008221)Startup Research Fund of Zhengzhou University(32211716)+3 种基金Key Scientific Research Projects of Colleges and Universities in Henan Province(21A530005)Guangdong Basic and Applied Basic Research Foundation(2021A1515110789)Hunan Provincial Natural Science Foundation of China(2022JJ40431)Zhengzhou Collaborative Innovation Major Project。
文摘Spent cathode carbon(SCC)from aluminum electrolysis is a potential graphite resource.However,full use of the SCC remains a challenge,since it contains many hazardous substances(e.g.,fluoride salts,cyanides),encapsulated within the thick carbon layers and thus posing serious environmental concerns.This work presents a chemical oxidative exfoliation route to achieve the recycling of SCC and the decontaminated SCC with high-valued graphene oxide(GO)-like carbon structures(SCC-GO)is applied as an excellent adsorbent for organic pollutants.Specifically,after the oxidative exfoliation,the embedded hazardous constituents are fully exposed,facilitating their subsequent removal by aqueous leaching.Moreover,benefiting from the enhanced specific surface areas along with abundant O-containing functional groups,the as-produced SCC-GO,shows an adsorption capacity as high as 347 mg·g^(-1)when considering methylene blue as a pollutant model,which exceeds most of the recently reported carbon-based adsorbents.Our study provides a feasible solution for the efficient recycling of hazardous carbonaceous wastes.
基金the National Natural Science Foundation of China(Grant No.51804277)supported by the State Key Laboratory of Special Rare Metal Materials(No.SKL2020K004)Northwest Rare Metal Materials Research Institute.
文摘The properties of non-oxide materials are continuously revealed,and their applications in the fields of ceramics,energy,and catalysis are increasingly extensive.Regardless of the traditional binary materials or the MAX phases,the preparation methods,which are environmentally friendly,efficient,economical,and easy to scale-up,have always been the focus of attention.Molten salt synthesis has demonstrated unparalleled advantages in achieving non-oxide materials.In addition,with the development of the process in molten salt synthesis,it also shows great potential in scale-up production.In this review,the recent progress of molten salt synthesis in the preparation of binary non-oxide and MAX phase is reviewed,as well as some novel processes.The reaction mechanisms and the influence of synthetic conditions for certain materials are discussed in detail.The paper is finalized with the discussion of the application prospect and future research trends of molten salt synthesis in non-oxide materials.
基金the National Key R&D Program of China(Grant No.2016YFB0301100)Anhui Provincial Natural Science Foundation of China(Grant No.1808085QE152).
文摘The silicothermic reduction of magnesium was investigated by the non-isothermal thermoanalysis in flowing argon,while the traditional investigations of silicothermic process for magnesium reduction were carried out under vacuum conditions.Firstly,the thermal gravimetric(TG)and derivative thermogravimetric(DTG)characteristic of briquettes prepared with calcined dolomite,ferrosilicon and fluorite were characterized by the thermogravimetric analyzer(TGA)at different heating rates.The intrinsic chemical kinetic mechanism was identified as a formal chemical reaction with the Nth order type which showed apparent activation energy E and reaction order n were 290.168 kJ mol^(-1) and 1.076,respectively.Then,a novel technique of magnesium production without vacuum was put forward and a three-dimensional unsteady numerical model incorporating the chemical reaction,radiation,heat conduction and heat convection was established and simulated,which was verified by Pidgeon process and novel tech no logy.rIhe nu merical results showed that the cycle time of the novel technique could be reduced when the argon temperature was higher than 1343 K and the argon entrance velocity was over 0.05 m s^(-1).And the effect of the argon temperature on reduction degree was much larger than that of entrance velocity.
基金funded by the National Key Research and Development Program of China (Grant No. 2016YFB0301001 and 2016YFB0301101)Major Projects for Collaborative Innovation of Zhengzhou (Grant No.18XTZX12010)Certificate of Postdoctoral Research Grant in Henan Province (Grant No. 201903011)。
文摘Effect of the second phase in the micro-galvanic corrosion of a commercial Mg alloy containing rare earth elements, cast WE43 alloy,was investigated in 0.6 M NaCl solution and 0.6 M Na_(2)SO_(4)solution by scanning electron microscopy(SEM) observations, scanning Kelvin probe force microscopy(SKPFM) analysis, hydrogen evolution, weight loss measurement, and electrochemical techniques. It is confirmed that the second phase of cast WE43 alloy is more active than Mg matrix and exhibits an anodic role in the micro-galvanic corrosion with α-Mg matrix as cathode and dissolves preferentially in Na_(2)SO_(4)solution, in contrast to the situation in NaCl solution. The corrosion rate of cast WE43 alloy in Na_(2)SO_(4)solution is much higher than that in NaCl solution, which is different from the conventional wisdom and could be attributed to the different role of the second phase in the micro-galvanic corrosion in two solutions.
基金the National Natural Science Foundation of China(Grant No.51804277).
文摘The electrochemical behavior of Mg^(2+)and Al^(3+)in LiCl-KCl(mass 4:1)melt at 973 K was studied on a Mo electrode systematically by cyclic voltammetry,square wave voltammetry and chronopotentiometry.The results showed that the reductions of Mg^(2+)and Al^(3+)were reversible processes controlled by the rate of the mass transfer.When Mg^(2+)and Al^(3+)coexisted in LiCl-KCl melt,they had no significant effect on the reduction potential of each other.The equilibrium potentials of Mg^(2+)/Mg and Al^(3+)/Al were obtained by open circuit potential method.Their apparent standard potentials were also calculated in this system and the values were-2.52 V vs Cl_(2)/Cl^(−),-1.66 V vs Cl_(2)/Cl^(−),respectively.Correspondingly,the apparent Gibbs free energies of Mg^(2+)/Mg and Al^(3+)/Al were-485.71 kJ/mol^(-1),-480.78 kJ/mol^(-1).Finally,potentiostatic electrolysis was performed on a Mo electrode in LiCl-KCl-MgCl_(2)-AlCl_(3)(the mass ratio of MgCl_(2) to AlCl_(3) was 10:1)melt at different potentials.The components of the deposits were characterized by scanning electron microscope and energy dispersive spectroscopy.The study revealed that the content of Al in the deposit decreased as the overpotential increased and Al tended to segregate at the grain boundaries.
基金supported by the National Natural Science Foundation of China(22078277 and 21908185)the Project of Hunan Provincial Natural Science Foundation of China(2020JJ5532 and 2021JJ30658)+5 种基金the Degree&Postgraduate Education Reform Project of Hunan Provincial(XDCX2019B095 and CX20190489)the Guang Dong Basic and Applied Basic Research Foundation(2021A1515110789 and 2021A1515110136)the Science and Technology Innovation Program of Hunan Province(2021RC2089)the Research Initiation Project of Xiangtan University(KZ08076)the Environment-friendly Chemical Process Integration Technology Hunan Province Key Laboratorythe Collaborative Innovation Center of New Chemical Technologies for Environmental Benignity and Efficient Resource Utilization。
文摘2-methyl-tetrahydrofuran(2-MTHF)is a promising biofuel or fuel additive with excellent burning property,a versatile new-style solvent in organic synthesis,and an important medical intermediate.In this work,a one-pot selective conversion of furfural(FA)into 2-MTHF was carried out over Zn doped Co/NC catalysts.The Zn-Co/NC-1 catalyst with trace Zn dopant(0.38 wt%)exhibited the best performance(yield of 2-MTHF:93.8%).According to the characterizations,it was found that the Zn not only incorporates into the carbon support but also partially dopes into Co nanoparticles.Subsequently,theoretical calculations demonstrated that the doping of Zn in carbon support can effectively enhance the electron transfer from the support to the metallic Co particle,leading to the electron-rich Co surface.The presence of Zn was found to promote the dissociation of hydrogen and to lower the diffusion barrier of hydrogen atom,in favor of the hydrogenation/hydrodeoxygenation processes.Furthermore,the Zn doped models exhibit much lower barrier in breaking C–OH bond of FOL,resulting in higher activity for hydrodeoxygenation of FOL.These theoretical results are consistent with the in situ FT-IR analysis of adsorption substrates and intermediates over Zn doped catalyst.This work reveals the mechanism of dopant Zn tailoring the electronic structure and catalytic performance of active sites,providing a deep insight into the design of economical and high-performance catalysts for hydrogenation/hydrodeoxygenation of biomass feedstocks.
基金financially supported by the National Natural Science Foundation of China(No.51804277)the State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization,China(No.CNMRCUKF2008)+1 种基金the State Key Laboratory of Special Rare Metal Materials,China(No.SKL2020K004)the Northwest Rare Metal Materials Research Institute,China。
文摘The effects of fluoride ions(F^(-)) on the electrochemical behavior and coordination properties of titanium ions(Ti^(n+)) were studied in this work,by combining electrochemical and mathematical analysis as well as spectral techniques.The α was taken as a factor to indicate the molar concentration ratio of F^(-) and Ti^(n+).Cyclic voltammetry(CV),square wave voltammetry(SWV),and open circuit potential method(OCP)were used to study the electrochemical behavior of titanium ions under conditions of various α,and in-situ sampler was used to prepare molten salt samples when α equal to 0.0,1.0,2.0,3.0,4.0,5.0,6.0,and 8.0.And then,samples were analyzed by X-ray photoelectron spectroscopy(XPS) and Raman spectroscopy.The results showed that F^(-) in molten salt can reduce the reduction steps of titanium ions and greatly affects the proportion of valence titanium ions which making the high-valence titanium content increased and more stable.Ti^(2+) cannot be detected in the molten salt when α is higher than 3.0 and finally transferred to titanium ions with higher valence state.Investigation revealed that the mechanism behind those phenomenon is the coordination compounds(TiCl_(j) F_(i)^(m-)) forming.
基金This work was supported by the National Natural Science Foundation of China(No.21807117)Hunan Provincial Natural Science Foundation of China(Nos.2022JJ20052 and 2021JJ30788)+1 种基金the Science and Technology Innovation Program of Hunan Province(No.2022RC1109)Central South University Innovation-Driven Research Programme(No.2023CXQD021).
文摘Artificial cells are constructed from synthetic materials to imitate the biological functions of natural cells.By virtue of nanoengineering techniques,artificial cells with designed biomimetic functions provide alternatives to natural cells,showing vast potential for biomedical applications.Especially in cancer treatment,the deficiency of immunoactive macrophages results in tumor progression and immune resistance.To overcome the limitation,a BaSO_(4)@ZIF-8/transferrin(TRF)nanomacrophage(NMΦ)is herein constructed as an alternative to immunoactive macrophages.Alike to natural immunoactive macrophages,NMΦis stably retained in tumors through the specific affinity of TRF to tumor cells.Zn^(2+)as an“artificial cytokine”is then released from the ZIF-8 layer of NMΦunder tumor microenvironment.Similar as proinflammatory cytokines,Zn^(2+)can trigger cell anoikis to expose tumor antigens,which are selectively captured by the BaSO_(4)cavities.Therefore,the hierarchical nanostructure of NMΦs allows them to mediate immunogenic death of tumor cells and subsequent antigen capture for T cell activation to fabricate long-term antitumor immunity.As a proof-of-concept,the NMΦmimics the biological functions of macrophage,including tumor residence,cytokine release,antigen capture and immune activation,which is hopeful to provide a paradigm for the design and biomedical applications of artificial cells.
基金This work was supported by the National Natural Science Foundation of China(51920105007,51904300 and 52104277)the Jiangsu Natural Science Fund-Youth Fund(BK20210500).
文摘Since solid-liquid interfacial nanobubbles(INBs)were first imaged,their long-term stability and large contact angle have been perplexing scientists.This study aimed to investigate the influence of internal gas density and external gas monolayers on the contact angle and stability of INB using molecular dynamics simulations.First,the contact angle of a water droplet was simulated at different nitrogen densities.The results showed that the contact angle increased sharply with an increase in nitrogen density,which was mainly caused by the decrease in solid-gas interfacial tension.However,when the nitrogen density reached 2.57 nm^(-3),an intervening gas monolayer(GML)was formed between the solid and water.After the formation of GML,the contact angle slightly increased with increasing gas density.The contact angle increased to 180°when the nitrogen density reached 11.38 nm^(-3),indicating that INBs transformed into a gas layer when they were too small.For substrates with different hydrophobicities,the contact angle after the formation of GML was always larger than 140°and it was weakly correlated with substrate hydrophobicity.The increase in contact angle with gas density represents the evolution of contact angle from macro-to nano-bubble,while the formation of GML may correspond to stable INBs.The potential of mean force curves demonstrated that the substrate with GML could attract gas molecules from a longer distance without the existence of a potential barrier compared with the bare substrate,indicating the potential of GML to act as a gas-collecting panel.Further research indicated that GML can function as a channel to transport gas molecules to INBs,which favors stability of INBs.This research may shed new light on the mechanisms underlying abnormal contact angle and long-term stability of INBs.
基金the National Natural Science Foundation of China(Grant No.51804277)supported by the State Key Laboratory of Special Rare Metal Materials(No.SKL2020K004)+1 种基金Northwest Rare Metal Materials Research Institutesupported by the State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization(No.CNMRCUKF2008)。
文摘Spent catalyst used for denitration by selective catalytic reduction(spent SCR denitration catalysts) is one of the important urban mines due to the high content of TiO_(2)(~85 wt%) and the massive accumulation amount(over 100,000 tons),therefore,value-added reutilization of titanium in spent SCR catalysts is considerably meaningful.In this paper,a novel method is proposed for converting the titanium oxide in spent SCR denitration catalysts to metallic titanium.Specifically,titanium dioxide(TiO_(2)) was firstly obtained from spent SCR denitration catalysts after removing the impurities by hydrometallurgy process.Then,TiO_(2) is converted to Ti_(2)CO by carbothermic reduction method,and Ti_(2)CO was further purified by oleic acid capture.Finally,by utilizing the as-prepared Ti_(2)CO as the consumable anode in the NaCl-KCl molten salt,high-purity metallic titanium was deposited at cathode,all confirming the feasibility for the conversion of low-grade TiO_(2) in the spent catalysts,from 60 wt% to high-purity metallic Ti(99.5 wt%), furthermore,the energy consumption of this process is 3950 kWh tonne-1 Ti,which is lower than that of most traditional titanium metallurgy methods.The method herein can provide new insights for the value-added recycling of titanium resources in urban mines.
基金supported by the National Natural Science Foundation of China(Nos.51974110,52074109 and 52274261)the Key Scientific and Technological Project of Henan Province(No.202102210183)the Coal Green Conversion Outstanding Foreign Scientists Foundation of Henan Province(No.GZS2020012).
文摘Materialization of coal is one of effective and clean pathways for its utilization. The microstructures of coal-based carbon materials have an important influence on their functional applications. Herein, the microstructural evolution of anthracite in the temperature range of 1000–2800 ℃ was systematically investigated to provide a guidance for the microstructural regulation of coal-based carbon materials.The results indicate that the microstructure of anthracite undergoes an important change during carbonization-graphitization process. As the temperature increases, aromatic layers in anthracite gradually transform into disordered graphite microcrystals and further grow into ordered graphite microcrystals, and then ordered graphite microcrystals are laterally linked to form pseudo-graphite phase and eventually transformed into highly ordered graphite-like sheets. In particular, 2000–2200 ℃ is a critical temperature region for the qualitative change of ordered graphite crystallites to pseudo-graphite phase,in which the relevant structural parameters including stacking height, crystallite lateral size and graphitization degree show a rapid increase. Moreover, both aromaticity and graphitization degree have a linear positive correlation with carbonization-graphitization temperature in a specific temperature range.Besides, after initial carbonization, some defect structures in anthracite such as aliphatic carbon and oxygen-containing functional groups are released in the form of gaseous low-molecular volatiles along with an increased pore structure, and the intermediates derived from minerals could facilitate the conversion of sp^(3) amorphous carbon to sp^(2) graphitic carbon. This work provides a valuable reference for the rational design of microstructure of coal-based carbon materials.
基金financially supported by the National Natural Science Foundation of China (Nos.21931012,21971244,92163209,and 52174387)the Education Department of Henan Province (No.20A430024)。
文摘Safe, green and efficient industrial production has always been the pursuit of the chemical industry. Since thermal energy is the driving force for most of chemical reactions, an ideal reaction tank would have the capacity to automatically regulate heat conduction rate. In detail, this reaction tank should endow an ability that resists the heat loss when the reaction temperature is lower than the target, while accelerating the heat dissipation when the system is overheated. In this case, this smart reactor can not only minimize energy consumption but also reduce safety risks.Hollow structures are known to reduce heat conductivity. Particularly, the hollow structure with multishells can provide more interfaces and thus further inhibit heat transmission, which would be more favorable for heat isolation. Step forward, by coupling HoMSs with temperature-sensitive polymer, a smart heat isolation material has been fabricated in this work. It performs as a good heat isolator at a relatively lower temperature. A heat insulation effect of 6.5℃ can be achieved for the TSPU/3S–TiO_(2)HoMSs with a thickness of 1 mm under the temperature field of 50℃.The thermal conductivity of composite material would be raised under overheating conditions. Furthermore, this composite displays an unusual two-stage phase transformation during heating. Benefiting from the unique multishelled structure, energy is found to be gradually guided into the hollow structure and stored inside. This localized heat accumulation enables the composite to be a potential coating material for intelligent thermal-regulator and site-defined micro-reactor.
基金supported by the National Natural Science Foundation of China(51574240,U1704252)Natural Science Foundation of Jiangsu Province(BK20150192).
文摘The structural and electronic properties of bastnaesite were studied by using the first-principles method based on the density functional theory(DFT).The geometry structure of bastnaesite was first optimized,and then the Mulliken populations,electron density and density of states were calculated and further analyzed in detail.The calculation results reveal that it mainly ruptures along the ionic Ce-O and Ce-F bonds during the cleavage of bastnaesite,leaving≡Ce^+,≡F^-and≡CO3^-dangling bonds exposed on the cleavage surface of bastnaesite.Combined with contact angle measurement,surface complexation theory and XPS analysis,the implications of structural and electronic properties on bastnaesite flotation reactions were studied.The hydration of exposed strong ionic bond on cleavage surface results in hydrophilic surface.According to surface complexation theory,the formed surface groups are≡CeOH^0,≡CO3 H^0 and≡FH^0 groups.The investigated metal ions and flotation reagents complex with surface≡CeOH^0 groups,while≡CO3H^0 and≡FH^0 groups are not involved in the complexation.The high activity of Ce atoms facilitates these surface reactions.
基金This work was supported by the National Key R&D Program of China(No.2018YFA0703504)the National Natural Science Foundation of China(Nos.21971244,51932001,52174387)the Project of the Education Department of Henan Province,China(No.20A430024).
文摘Graphdiyne(GDY)has the unique feature in the topological ordered arranged sp-and sp^(2)-hybridized carbon atoms,thus deriving a series of 2D allotropes.Due to inhomogeneousπ-bonding and carbon orbital overlap between different hybrid carbon atoms,GDY possesses a natural band gap with a Dirac cones structure.And GDY exhibits semiconductor property with a conductivity of 2.516×10^(−4) S/m at room temperature.The topological distribution of alkyne and benzene bonds of GDY makes its surface charge distribution extremely uneven,which produces high intrinsic activity for further modification.Its unique molecular structure endows the specific interaction with various species,such as ions,atoms,molecules and nanoparticles,showing excellent charge transport capability and unique advantages in mass transfer and energy conversion.From the view of the interaction principle between GDY and different compositions,we summarized the application of GDY-based materials in the fields of catalysis,energy conversion and storage,biological detection and so on.
基金Projects(21636010,21878342)supported by the National Natural Science Foundation of ChinaProject(2019JJ50758)supported by the Hunan Provincial Natural Science Foundation of China+1 种基金Project(2019TP1001)supported by the Hunan Provincial Science and Technology Plan Project of ChinaProject(CX20190097)supported by the Fundamental Research Funds for the Central Universities,China。
文摘In traditional ceramic processing techniques,high sintering temperature is necessary to achieve fully dense microstructures.But it can cause various problems including warpage,overfiring,element evaporation,and polymorphic transformation.To overcome these drawbacks,a novel processing technique called“tcold sintering process(CSP)”has been explored by Randall et al.CSP enables densification of ceramics at ultra-low temperature(<300℃)with the assistance o f transient aqueous solution and applied pressure.In CSP,the processing conditions including aqueous solution,pressure,temperature,and sintering duration play critical roles in the densification and properties of ceramics,which will be reviewed.The review will also include the applications of CSP in solid-state rechargeable batteries.Finally,the perspectives about CSP is proposed.
基金supported by the National Natural Science Foundation of China(21925405 and 201874005)the National Key Research and Development Program of China(grant no.2018YFA0208800)and the Chinese Academy of Sciences(XDA23030106 and YJKYYQ20180044).
文摘Functional nanoparticles(NPs)with unique photoelectric,mechanical,magnetic,and chemical properties have attracted considerable attention.Aggregated NPs rather than individual NPs are generally required for sensing,electronics,and catalysis.However,the transformation of functionalNPaggregates into scalable,controllable,and affordable functional devices remains challenging.Printing is a promising additive manufacturing technology for fabricating devices fromNPbuilding blocks because of its capabilities for rapid prototyping and versatile multifunctional manufacturing.This paper reviews recent advances in NP patterning based on the combination of self-assembly and printing technologies(including two-,three-,and four-dimensional printing),introduces the basic characteristics of these methods,and discusses various fields of NP patterning applications.
基金supported by the National Key R&D Program of China(2018YFA0703504 and 2022YFA1204502)the National Natural Science Foundation of China(51932001,52201284,and 52174387)。
基金financially supported by the National Natural Science Foundation of China(No.51574240)the Natural Science Foundation of Jiangxi Province,China(Nos.20181BBG70050 and 20171BBG70044).
文摘The effects of shear strength on aggregation flotation processes for fine spodumene(particle size less than 19μm)were investigated in this study.Sodium oleate was used as a surfactant and collector.The shear strength was controlled by varying the agitation speed of a selfmade stirring apparatus.The aggregation process was studied by measuring the continuous transformations in the size distribution and shape of flocs.The results showed that as the shear strength increased,the distribution of fine spodumene transformed from bimodal to unimodal mode.The flocs tended to bridge more branches with a high shear strength and form globule-like flocs with very high strengths.The parameter"aggregation degree"was introduced to evaluate the aggregation process as a function of shear strength.The flotation rate of flocs formed with different shear strengths was also studied.These results demonstrated that the flotation rate was closely related to shear strength and that there was a close correlation between this and aggregation degree.These results could be used to guide the actual production of fine particles via shear aggregation flotation.
