Preparing rare earth carbonates from rare earth chlorides is a common step in the smelting process for all rare earth ores;however,it produces large amounts of ammoniacal nitrogen wastewater and a chloriderich precipi...Preparing rare earth carbonates from rare earth chlorides is a common step in the smelting process for all rare earth ores;however,it produces large amounts of ammoniacal nitrogen wastewater and a chloriderich precipitate.This study proposes a novel,green and simple process for preparing low-chlorine lanthanum carbonate via a multi-membrane electroconversion approach.The effects of the CO_(2) flow rate,current density,lanthanum chloride concentration,and electroconversion time on the electroconversion process were systematically explored.Under the optimal process conditions(CO_(2) flow rate=0.5 L/min,current density=25 mA/cm^(2),LaCl_(3) concentration=0.3 mol/L,electroconversion time=60 min),a current efficiency of 75.77% was obtained,along with a unit energy consumption of5.44 kWh/kg.X-ray diffraction,Fourier transform infrared spectroscopy,thermogravimetric analysis,and laser particle size analysis results indicate that a pure La_(2)(CO_(3))_(3)·8H_(2)O product is obtained with a median particle size of 6.53 μm and chlorine content of 0.0021%.In addition,scanning electron microscopy and transmission electron microscopy observations indicate that the crystallisation and growth of La_(2)(CO_(3))_(3)·8H_(2)O conform to the oriented attachment and Ostwald ripening mechanisms.Thus,the proposed multi-membrane electroconversion method provides guidance toward the clean transformation of rare earth chlorides to low-chlorine lanthanum carbonates.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
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
To effectively alleviate the ever-increasing energy crisis and environmental issues,clean and sustainable energy-related materials as well as the corresponding storage/conversion devices are in urgent demand.Silicon(S...To effectively alleviate the ever-increasing energy crisis and environmental issues,clean and sustainable energy-related materials as well as the corresponding storage/conversion devices are in urgent demand.Silicon(Si) with the second most elemental abundance on the crust in the form of silicate or silica(SiO_(2)) minerals,is an advanced emerging material showing high performance in energy-related fields(e.g.batteries,photocatalytic hydrogen evolution).For the improved performance in industry-scale applications,Si materials with delicate nanostructures and ideal compositions in a massive production are highly cherished.On account of the reserve,low cost and diverse micro-nanostructures,silicate minerals are proposed as promising raw materials.In the article,crystal structures and the reduction approaches for silicate minerals,as well as recent progress on the as-reduced Si products for clean energy storage/conversion,are presented systematically.Moreover,some cutting-edge fields involving Si materials are discussed,which may offer deep insights into the rational design of advanced Si nanostructures for extended energy-related fields.展开更多
As the poor dispersion of oily collectors and the inferior hydrophobicity of the mineral surface, the lowrank coal has an unsatisfactory flotation performance when using traditional collectors. In this paper, an ionic...As the poor dispersion of oily collectors and the inferior hydrophobicity of the mineral surface, the lowrank coal has an unsatisfactory flotation performance when using traditional collectors. In this paper, an ionic liquid microemulsion was used as a collector to enhance its floatability. Flotation test results demonstrated the microemulsion collector exhibited a superior collecting ability. A satisfactory separation performance of 78.66% combustible material recovery was obtained with the microemulsion collector consumption of 6 kg/t, which was equivalent to the flotation performance of diesel at a dosage of25 kg/t. The dispersion behavior of the microemulsion collector was investigated using the CryogenicTransmission Electron Microscopy. The interaction mechanism of the microemulsion collector on enhancing the low-rank coal flotation was elucidated through the Zeta potential and contact angle measurements, the Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis.The microemulsion collector exhibited superior dispersibility, which was dispersed into positively charged oil droplets with an average size of 160.21 nm in the pulp. Furthermore, the nano-oil droplets could be more efficiently adsorbed on the low-rank coal surface through electrostatic attraction, resulting in the improvement of its hydrophobicity. Thus, the microemulsion collector shows great application potential in improving the flotation performance of low-rank coal.展开更多
An ionic liquid(IL)catalyzed solvent-free process was developed for the direct synthesis of chalcone and its derivatives by using substituted acetophenones and benzaldehydes via aldol reaction under mild conditions.A ...An ionic liquid(IL)catalyzed solvent-free process was developed for the direct synthesis of chalcone and its derivatives by using substituted acetophenones and benzaldehydes via aldol reaction under mild conditions.A series of acidic and basic ILs were selected and screened.The influences of cations and reaction conditions on product yield and selectivity were systematically investigated.The[Bmim]OH was identified as the optimal IL,with the highest yield and selectivity reaching up to 96.7% and 100%,respectively.A reaction mechanism-based kinetic model was established and regressed with experimental data,revealing the β-Hydroxylketone dehydrolysis with activation barrier of 37.8 kJ·mol^(-1) was observed as the ratecontrolling step.展开更多
A series of flexible and self-standing coal-derived carbon fibers(CCFs)were fabricated through electro-spinning coupled with carbonization using bituminous coal and polyacrylonitrile(PAN)as the carbon precursors.These...A series of flexible and self-standing coal-derived carbon fibers(CCFs)were fabricated through electro-spinning coupled with carbonization using bituminous coal and polyacrylonitrile(PAN)as the carbon precursors.These CCFs were utilized as free-standing lithium-ion battery(LIB)anodes.Optimizing car-bonization temperature reveals that the CCFs exhibit a one-dimensional solid linear structure with a uni-form distribution of graphite-like microcrystals.These fibers possess a dense structure and smooth surface,with averaging diameter from approximately 125.0 to 210.0 nm at carbonization temperatures ranging from 600 to 900℃.During electrospinning and carbonization,the aromatic rings enriched in bituminous coal crosslink with PAN chains,forming a robust three-dimensional(3D)framework.This 3D microstructure significantly enhances the flexibility and tensile strength of CCFs,while increasing the graphite-like sp^(2)microcrystalline carbon content,thus improving electrical conductivity.The CCFs carbonized at 700℃demonstrate an optimal balance of sp^(3)amorphous and sp^(2)graphite-like carbons.The average diameter of CCFs-700 is 177 nm and the specific surface area(SSA)is 7.2 m^(2)g^(-1).Additionally,the fibers contain oxygen-containing functional groups,as well as nitrogen-containing func-tional groups,including pyridinic nitrogen and pyrrolic nitrogen.Owing to its characteristics,the CCFs-700 showcases remarkable electrochemical performance,delivering a high reversible capacity of 631.4 mAh g^(-1).CCFs-700 also exhibit outstanding cycle stability,which retains approximately all of their first capacity(400.1 mAh g^(-1))after 120 cycles.This research offers an economical yet scalable approach for producing flexible and self-supporting anodes for LIBs that do not require current collectors,binders and conductive additives,thereby simplifying the electrode fabrication process.展开更多
Cobalt has excellent electrochemical,magnetic,and heat properties.As a strategic resource,it has been applied in many hightech products.However,the recent rapid growth of the battery industry has substantially deplete...Cobalt has excellent electrochemical,magnetic,and heat properties.As a strategic resource,it has been applied in many hightech products.However,the recent rapid growth of the battery industry has substantially depleted cobalt resources,leading to a crisis of cobalt resource supply.The paper examines cobalt ore reserves and distribution,and the recent development and consumption of cobalt resources are summarized as well.In addition,the principles,advantages and disadvantages,and research status of various methods are discussed comprehensively.It can be concluded that the use of diverse sources(Cu-Co ores,Ni-Co ores,zinc plant residues,and waste cobalt products)for cobalt production should be enhanced to meet developmental requirements.Furthermore,in recovery technology,the pyro-hydrometallurgical process employs pyrometallurgy as the pretreatment to modify the phase structure of cobalt minerals,enhancing its recovery in the hydrometallurgical stage and facilitating high-purity cobalt production.Consequently,it represents a promising technology for future cobalt recovery.Lastly,based on the above conclusions,the prospects for cobalt are assessed regarding cobalt ore processing and sustainable cobalt recycling,for which further study should be conducted.展开更多
A novel small molecule depressant(M-DEP)was used to separate chalcopyrite and molybdenite via flotation.The results showed that M-DEP had an excellent selective depression on molybdenite,while had little effect on the...A novel small molecule depressant(M-DEP)was used to separate chalcopyrite and molybdenite via flotation.The results showed that M-DEP had an excellent selective depression on molybdenite,while had little effect on the flotation of chalcopyrite.The adsorption capacity of M-DEP on the surface of molybdenite was greater than that on chalcopyrite surface.The adsorption of M-DEP reduced the floatability of molybdenite and had less effect on the floatability of chalcopyrite,which was due to its different adsorption modes on the surface of the two minerals.Furthermore,the interaction between chalcopyrite and M-DEP was mainly chemical interaction,and almost all of the adsorbed M-DEP molecules were removed and replaced by sodium butyl xanthate(SBX).By contrast,hydrophobic interaction was the main way in which M-DEP was adsorbed on the molybdenite surface with little chemical interaction,which was less interfered by SBX addition.Therefore,M-DEP had a super selective depression on molybdenite.The study provided a novel depressant and approach for the deep separation of chalcopyrite and molybdenite via flotation.展开更多
Pyrite is separated from other minerals mainly by fotation.However,the hydrophilicity of pyrite is afected by many factors,causing it to easily enter the concentrate and consequently reduce the quality of concentrate....Pyrite is separated from other minerals mainly by fotation.However,the hydrophilicity of pyrite is afected by many factors,causing it to easily enter the concentrate and consequently reduce the quality of concentrate.Highly efcient pyrite depressants can be selectively adsorbed on the surface of pyrite to improve its hydrophilicity,thereby increasing the fotation separation efciency.Understanding the fundamental inhibition mechanism of depressants on pyrite is a prerequisite to improve the fotation desulfurization efciency.The inhibition ability and mechanism of diferent types of pyrite depressants are reviewed in this manuscript.In recent years,molecular simulation has increasingly become a powerful tool to study the interaction between reagents and minerals,shedding new light on the adsorption mechanisms of reagents on mineral surfaces at the atomic and electronic levels.The properties of sulfde mineral and fotation reagents as well as the microscopic adsorption mechanistic studies of reagents on mineral surfaces based on quantum chemistry and molecular simulation are also reviewed.展开更多
The loss of rare earths(REs)takes place during the pre-decalcification process of mixed rare earth concentrate.In an effort to reduce such RE loss,a novel idea to improve the leaching selectivity of Ca to REs by apply...The loss of rare earths(REs)takes place during the pre-decalcification process of mixed rare earth concentrate.In an effort to reduce such RE loss,a novel idea to improve the leaching selectivity of Ca to REs by applying selective mechanical activation was proposed.First,regarding the key minerals affecting the leaching selectivity of Ca to REs,the differences in the mechanical activation behaviors of CaF_(2) and REFCO_(3) were studied,and we find that the lattice strain of CaF_(2) increases from 0.21%to 0.42%,whereas that of REFCO_(3) increases from 0.31%to 0.40%.Notably,CaF_(2) demonstrates a larger lattice strain than REFCO_(3),indicating greater mechanical activation energy storage and higher leaching activity.Next,the HCl leaching process was studied.A significant leaching selectivity of Ca to REs,from 21.6 to 35.1,is achieved through mechanical activation.The Ca leaching rate reaches 80.7%when the RE loss is 2.3%in the activated sample.This study provides an novel approach for achieving selective extraction of specific components via mechanical activation pretreatment.展开更多
Mineral flotation plays a pivotal role in mineral processing.The oxidation of sulfide ores can alter the surface properties of minerals,thereby optimizing their separation efficiency.This paper provides a comprehensiv...Mineral flotation plays a pivotal role in mineral processing.The oxidation of sulfide ores can alter the surface properties of minerals,thereby optimizing their separation efficiency.This paper provides a comprehensive review of the various oxidation methods applied in sulfide mineral flotation,including chemical oxidation,electrochemical oxidation,biological oxidation,thermal pretreatment,and plasma treatment.Additionally,it discusses the impact of mineral oxidation on flotation performance,focusing on modifications to surface properties such as the formation of oxidation products,changes in zeta potential,and alterations in hydrophobicity,as well as the degradation of flotation reagents and changes in reagent adsorption.However,challenges remain in the oxidation-flotation separation of sulfide minerals,including insufficient control precision of the oxidation process,environmental and cost concerns associated with certain oxidation methods,and a lack of in-depth research into the oxidation-flotation mechanism.Future advancements in oxidative flotation will focus on intelligent monitoring,precise control,composite oxidation systems,and in situ analysis to understand surface microvariations and oxidation-product relationships.Cost control will rely on the use of low-cost oxidants,durable electrodes,and energy-efficient equipment.Tailored processing solutions for complex ores integrating bioflotation,physical separation,and other technologies will enhance recovery rates and concentrate quality,promoting broader applications.展开更多
The classical Fenton oxidation process(CFOP)is a versatile and effective application that is generally applied for recalcitrant pollutant removal.However,excess iron sludge production largely restricts its widespread ...The classical Fenton oxidation process(CFOP)is a versatile and effective application that is generally applied for recalcitrant pollutant removal.However,excess iron sludge production largely restricts its widespread application.Fenton sludge is a hazardous solid waste,which is a complex heterogeneous mixture with Fe(OH)3,organic matter,heavy metals,microorganisms,sediment impurities,and moisture.Although studies have aimed to utilize specific Fenton sludge resources based on their iron-rich characteristics,few reports have fully reviewed the utilization of Fenton sludge.As such,this review details current sustainable Fenton sludge reuse systems that are applied during wastewater treatment.Specifically,coagulant preparation,the reuse of Fenton sludge as an iron source in the Fenton process and as a synthetic heterogeneous catalyst/adsorbent,as well as the application of the Fenton sludge reuse system as a heterogeneous catalyst for resource utilization.This is the first review article to comprehensively summarize the utilization of Fenton sludge.In addition,this review suggests future research ideas to enhance the cost-effectiveness,environmental sustainability,and large-scale feasibility of Fenton sludge applications.展开更多
Increasing global population and decreasing arable land pose tremendous pressures to agricultural production.The application of conventional chemical fertilizers improves agricultural production,but causes serious env...Increasing global population and decreasing arable land pose tremendous pressures to agricultural production.The application of conventional chemical fertilizers improves agricultural production,but causes serious environmental problems and significant economic burdens.Biochar gains increasing interest as a soil amendment.Recently,more and more attentions have been paid to biochar-based slowrelease of fertilizers(SRFs)due to the unique properties of biochar.This review summarizes recent advances in the development,synthesis,application,and tentative mechanism of biochar-based SRFs.The development mainly undergoes three stages:(i)soil amendment using biochar,(ii)interactions between nutrients and biochar,and(iii)biochar-based SRFs.Various methods are proposed to improve the fertilizer efficiency of biochar,majorly including in-situ pyrolysis,co-pyrolysis,impregnation,encapsulation,and granulation.Considering the distinct features of different methods,the integrated methods are promising for fabricating effective biochar-based SRFs.The in-depth understanding of the mechanism of nutrient loading and slow release is discussed based on current knowledge.Additionally,the perspectives and challenges of the potential application of biochar-based SRFs are described.Knowledge surveyed from this review indicates that applying biochar-based SRFs is a viable way of promoting sustainable agriculture.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
基金supported by the Postdoctoral Research Project of Henan Province (HN2022004)Zhongyuan Critical Metals Laboratory(GJJSGFYQ202319,GJJSGFYQ202328)+2 种基金Open Fund project of Key Laboratory of Ecological Metallurgy of Multi-Metal Intergrown Ores of Ministry of Education(NEMM2022003)Guangxi Science and Technology Major Project (Guike AA22068078)National Key R&D Program of China (2021YFC2902604)。
文摘Preparing rare earth carbonates from rare earth chlorides is a common step in the smelting process for all rare earth ores;however,it produces large amounts of ammoniacal nitrogen wastewater and a chloriderich precipitate.This study proposes a novel,green and simple process for preparing low-chlorine lanthanum carbonate via a multi-membrane electroconversion approach.The effects of the CO_(2) flow rate,current density,lanthanum chloride concentration,and electroconversion time on the electroconversion process were systematically explored.Under the optimal process conditions(CO_(2) flow rate=0.5 L/min,current density=25 mA/cm^(2),LaCl_(3) concentration=0.3 mol/L,electroconversion time=60 min),a current efficiency of 75.77% was obtained,along with a unit energy consumption of5.44 kWh/kg.X-ray diffraction,Fourier transform infrared spectroscopy,thermogravimetric analysis,and laser particle size analysis results indicate that a pure La_(2)(CO_(3))_(3)·8H_(2)O product is obtained with a median particle size of 6.53 μm and chlorine content of 0.0021%.In addition,scanning electron microscopy and transmission electron microscopy observations indicate that the crystallisation and growth of La_(2)(CO_(3))_(3)·8H_(2)O conform to the oriented attachment and Ostwald ripening mechanisms.Thus,the proposed multi-membrane electroconversion method provides guidance toward the clean transformation of rare earth chlorides to low-chlorine lanthanum carbonates.
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financially supported by National Natural Science Foundation of China(51702291,51874357,U20A20123)the China Postdoctoral Science Foundation(2020M682352)+1 种基金State Key Laboratory of Powder Metallurgy,Central South University,Changsha,Chinasupport from the Youth Talent Program of Zhengzhou University and Henan Provincial Key Technology R&D Program(212102210597)。
文摘To effectively alleviate the ever-increasing energy crisis and environmental issues,clean and sustainable energy-related materials as well as the corresponding storage/conversion devices are in urgent demand.Silicon(Si) with the second most elemental abundance on the crust in the form of silicate or silica(SiO_(2)) minerals,is an advanced emerging material showing high performance in energy-related fields(e.g.batteries,photocatalytic hydrogen evolution).For the improved performance in industry-scale applications,Si materials with delicate nanostructures and ideal compositions in a massive production are highly cherished.On account of the reserve,low cost and diverse micro-nanostructures,silicate minerals are proposed as promising raw materials.In the article,crystal structures and the reduction approaches for silicate minerals,as well as recent progress on the as-reduced Si products for clean energy storage/conversion,are presented systematically.Moreover,some cutting-edge fields involving Si materials are discussed,which may offer deep insights into the rational design of advanced Si nanostructures for extended energy-related fields.
基金financially supported by the National Key Research and Development Program of China (No. 2020YFC1908801)the National Natural Science Foundation of China (No. 52204287)+1 种基金the National Natural Science Foundation of China (No. 52004250)the Key R&D and Promotion Projects in Henan Province (No. 212102310009)。
文摘As the poor dispersion of oily collectors and the inferior hydrophobicity of the mineral surface, the lowrank coal has an unsatisfactory flotation performance when using traditional collectors. In this paper, an ionic liquid microemulsion was used as a collector to enhance its floatability. Flotation test results demonstrated the microemulsion collector exhibited a superior collecting ability. A satisfactory separation performance of 78.66% combustible material recovery was obtained with the microemulsion collector consumption of 6 kg/t, which was equivalent to the flotation performance of diesel at a dosage of25 kg/t. The dispersion behavior of the microemulsion collector was investigated using the CryogenicTransmission Electron Microscopy. The interaction mechanism of the microemulsion collector on enhancing the low-rank coal flotation was elucidated through the Zeta potential and contact angle measurements, the Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis.The microemulsion collector exhibited superior dispersibility, which was dispersed into positively charged oil droplets with an average size of 160.21 nm in the pulp. Furthermore, the nano-oil droplets could be more efficiently adsorbed on the low-rank coal surface through electrostatic attraction, resulting in the improvement of its hydrophobicity. Thus, the microemulsion collector shows great application potential in improving the flotation performance of low-rank coal.
基金We thank the financial support of Major Program of National Natural Science Foundation of China(21890762)General Program of National Natural Science Foundation of China(21878293)+2 种基金National Natural Science Foundation of China(21676270)Key Research Program of Frontier Sciences,CAS(QYZDY-SSW-JSC011)the K.C.Wong Education Foundation(GJTD-2018-04).
文摘An ionic liquid(IL)catalyzed solvent-free process was developed for the direct synthesis of chalcone and its derivatives by using substituted acetophenones and benzaldehydes via aldol reaction under mild conditions.A series of acidic and basic ILs were selected and screened.The influences of cations and reaction conditions on product yield and selectivity were systematically investigated.The[Bmim]OH was identified as the optimal IL,with the highest yield and selectivity reaching up to 96.7% and 100%,respectively.A reaction mechanism-based kinetic model was established and regressed with experimental data,revealing the β-Hydroxylketone dehydrolysis with activation barrier of 37.8 kJ·mol^(-1) was observed as the ratecontrolling step.
基金supported by the National Natural Science Foundation of China(Nos.52474290,52274261,52074109,52304284)the Open Subjects of Henan Provincial Key Laboratory of Coal Green Conversion(No.CGCF202201)+1 种基金the Key Scientific and Technological Project of Henan Province(No.242102240008)the Key Scientific Research Projects of Colleges and Universities in Henan Province(No.24A440003).
文摘A series of flexible and self-standing coal-derived carbon fibers(CCFs)were fabricated through electro-spinning coupled with carbonization using bituminous coal and polyacrylonitrile(PAN)as the carbon precursors.These CCFs were utilized as free-standing lithium-ion battery(LIB)anodes.Optimizing car-bonization temperature reveals that the CCFs exhibit a one-dimensional solid linear structure with a uni-form distribution of graphite-like microcrystals.These fibers possess a dense structure and smooth surface,with averaging diameter from approximately 125.0 to 210.0 nm at carbonization temperatures ranging from 600 to 900℃.During electrospinning and carbonization,the aromatic rings enriched in bituminous coal crosslink with PAN chains,forming a robust three-dimensional(3D)framework.This 3D microstructure significantly enhances the flexibility and tensile strength of CCFs,while increasing the graphite-like sp^(2)microcrystalline carbon content,thus improving electrical conductivity.The CCFs carbonized at 700℃demonstrate an optimal balance of sp^(3)amorphous and sp^(2)graphite-like carbons.The average diameter of CCFs-700 is 177 nm and the specific surface area(SSA)is 7.2 m^(2)g^(-1).Additionally,the fibers contain oxygen-containing functional groups,as well as nitrogen-containing func-tional groups,including pyridinic nitrogen and pyrrolic nitrogen.Owing to its characteristics,the CCFs-700 showcases remarkable electrochemical performance,delivering a high reversible capacity of 631.4 mAh g^(-1).CCFs-700 also exhibit outstanding cycle stability,which retains approximately all of their first capacity(400.1 mAh g^(-1))after 120 cycles.This research offers an economical yet scalable approach for producing flexible and self-supporting anodes for LIBs that do not require current collectors,binders and conductive additives,thereby simplifying the electrode fabrication process.
基金the financial support of Guangxi Science and Technology Major Project(Guike AA22068078)the Natural Science Foundation of Henan Province(No.222300420548)+2 种基金Henan Province Science and Technology Research and Development plan joint Fund(No.232301420043)the Key Project of the National Key Research and Development Program of China(No.2021YFC2902604)Modern Analysis and Computing Centre in Zhengzhou University。
文摘Cobalt has excellent electrochemical,magnetic,and heat properties.As a strategic resource,it has been applied in many hightech products.However,the recent rapid growth of the battery industry has substantially depleted cobalt resources,leading to a crisis of cobalt resource supply.The paper examines cobalt ore reserves and distribution,and the recent development and consumption of cobalt resources are summarized as well.In addition,the principles,advantages and disadvantages,and research status of various methods are discussed comprehensively.It can be concluded that the use of diverse sources(Cu-Co ores,Ni-Co ores,zinc plant residues,and waste cobalt products)for cobalt production should be enhanced to meet developmental requirements.Furthermore,in recovery technology,the pyro-hydrometallurgical process employs pyrometallurgy as the pretreatment to modify the phase structure of cobalt minerals,enhancing its recovery in the hydrometallurgical stage and facilitating high-purity cobalt production.Consequently,it represents a promising technology for future cobalt recovery.Lastly,based on the above conclusions,the prospects for cobalt are assessed regarding cobalt ore processing and sustainable cobalt recycling,for which further study should be conducted.
基金support from the Project of Zhongyuan Critical Metals Laboratory(No.GJJSGFYQ202334)Natural Science Foundation of Henan Province(No.242300420002)+1 种基金National key research and development program(No.2020YFC1908804)National Natural Science Foundation of China(No.51804275).Moreover,we also thank Modern Analysis and Gene Sequencing Centre in Zhengzhou University.
文摘A novel small molecule depressant(M-DEP)was used to separate chalcopyrite and molybdenite via flotation.The results showed that M-DEP had an excellent selective depression on molybdenite,while had little effect on the flotation of chalcopyrite.The adsorption capacity of M-DEP on the surface of molybdenite was greater than that on chalcopyrite surface.The adsorption of M-DEP reduced the floatability of molybdenite and had less effect on the floatability of chalcopyrite,which was due to its different adsorption modes on the surface of the two minerals.Furthermore,the interaction between chalcopyrite and M-DEP was mainly chemical interaction,and almost all of the adsorbed M-DEP molecules were removed and replaced by sodium butyl xanthate(SBX).By contrast,hydrophobic interaction was the main way in which M-DEP was adsorbed on the molybdenite surface with little chemical interaction,which was less interfered by SBX addition.Therefore,M-DEP had a super selective depression on molybdenite.The study provided a novel depressant and approach for the deep separation of chalcopyrite and molybdenite via flotation.
基金supported by the following:“Foundation for University Key Teacher by Henan Province”(No.2020GGJS051)“Key Project of Science and Technology Research of Education Department of Henan Province”(No.20A440004)+2 种基金“The Henan Polytechnic University Science Fund for Distinguished Young Scholars”(No.J2021-1)“Foundation for University Key Teacher by Henan Polytechnic University”(No.2017XQG-12)“Henan Key Laboratory of Coal Green Conversion”(No.CGCF202009).
文摘Pyrite is separated from other minerals mainly by fotation.However,the hydrophilicity of pyrite is afected by many factors,causing it to easily enter the concentrate and consequently reduce the quality of concentrate.Highly efcient pyrite depressants can be selectively adsorbed on the surface of pyrite to improve its hydrophilicity,thereby increasing the fotation separation efciency.Understanding the fundamental inhibition mechanism of depressants on pyrite is a prerequisite to improve the fotation desulfurization efciency.The inhibition ability and mechanism of diferent types of pyrite depressants are reviewed in this manuscript.In recent years,molecular simulation has increasingly become a powerful tool to study the interaction between reagents and minerals,shedding new light on the adsorption mechanisms of reagents on mineral surfaces at the atomic and electronic levels.The properties of sulfde mineral and fotation reagents as well as the microscopic adsorption mechanistic studies of reagents on mineral surfaces based on quantum chemistry and molecular simulation are also reviewed.
基金Project supported by the National Natural Science Foundation of China(52004252)Natural Science Foundation ofHenan Province(222300420548)Strategic Research and Consulting Project of Chinese Academy of Engineering(2022-XBZD-07)。
文摘The loss of rare earths(REs)takes place during the pre-decalcification process of mixed rare earth concentrate.In an effort to reduce such RE loss,a novel idea to improve the leaching selectivity of Ca to REs by applying selective mechanical activation was proposed.First,regarding the key minerals affecting the leaching selectivity of Ca to REs,the differences in the mechanical activation behaviors of CaF_(2) and REFCO_(3) were studied,and we find that the lattice strain of CaF_(2) increases from 0.21%to 0.42%,whereas that of REFCO_(3) increases from 0.31%to 0.40%.Notably,CaF_(2) demonstrates a larger lattice strain than REFCO_(3),indicating greater mechanical activation energy storage and higher leaching activity.Next,the HCl leaching process was studied.A significant leaching selectivity of Ca to REs,from 21.6 to 35.1,is achieved through mechanical activation.The Ca leaching rate reaches 80.7%when the RE loss is 2.3%in the activated sample.This study provides an novel approach for achieving selective extraction of specific components via mechanical activation pretreatment.
基金the Project of Zhongyuan Critical Metals Laboratory(No.GJJSGFYQ202334)Natural Science Foundation of Henan Province(No.242300420002)+1 种基金National Key Research and Development Program(NO.2020YFC1908804)National Natural Science Foundation of China(No.51804275)
文摘Mineral flotation plays a pivotal role in mineral processing.The oxidation of sulfide ores can alter the surface properties of minerals,thereby optimizing their separation efficiency.This paper provides a comprehensive review of the various oxidation methods applied in sulfide mineral flotation,including chemical oxidation,electrochemical oxidation,biological oxidation,thermal pretreatment,and plasma treatment.Additionally,it discusses the impact of mineral oxidation on flotation performance,focusing on modifications to surface properties such as the formation of oxidation products,changes in zeta potential,and alterations in hydrophobicity,as well as the degradation of flotation reagents and changes in reagent adsorption.However,challenges remain in the oxidation-flotation separation of sulfide minerals,including insufficient control precision of the oxidation process,environmental and cost concerns associated with certain oxidation methods,and a lack of in-depth research into the oxidation-flotation mechanism.Future advancements in oxidative flotation will focus on intelligent monitoring,precise control,composite oxidation systems,and in situ analysis to understand surface microvariations and oxidation-product relationships.Cost control will rely on the use of low-cost oxidants,durable electrodes,and energy-efficient equipment.Tailored processing solutions for complex ores integrating bioflotation,physical separation,and other technologies will enhance recovery rates and concentrate quality,promoting broader applications.
基金support of the National Natural Science Foundation of China(Grant No.5210040121)Jiangsu Provincial Natural Science Foundation of Jiangsu Province(No.BK20210498)the fellowship of China Postdoctoral Science Foundation(No.2021M693420).
文摘The classical Fenton oxidation process(CFOP)is a versatile and effective application that is generally applied for recalcitrant pollutant removal.However,excess iron sludge production largely restricts its widespread application.Fenton sludge is a hazardous solid waste,which is a complex heterogeneous mixture with Fe(OH)3,organic matter,heavy metals,microorganisms,sediment impurities,and moisture.Although studies have aimed to utilize specific Fenton sludge resources based on their iron-rich characteristics,few reports have fully reviewed the utilization of Fenton sludge.As such,this review details current sustainable Fenton sludge reuse systems that are applied during wastewater treatment.Specifically,coagulant preparation,the reuse of Fenton sludge as an iron source in the Fenton process and as a synthetic heterogeneous catalyst/adsorbent,as well as the application of the Fenton sludge reuse system as a heterogeneous catalyst for resource utilization.This is the first review article to comprehensively summarize the utilization of Fenton sludge.In addition,this review suggests future research ideas to enhance the cost-effectiveness,environmental sustainability,and large-scale feasibility of Fenton sludge applications.
基金the National Key Research and Development Project(2020YFC1908802),Chinathe National Natural Science Foundation of China(U1704252 and 51804276),Chinathe Young Elite Scientist Sponsorship Program by CAST(2019QNRC001),China.
文摘Increasing global population and decreasing arable land pose tremendous pressures to agricultural production.The application of conventional chemical fertilizers improves agricultural production,but causes serious environmental problems and significant economic burdens.Biochar gains increasing interest as a soil amendment.Recently,more and more attentions have been paid to biochar-based slowrelease of fertilizers(SRFs)due to the unique properties of biochar.This review summarizes recent advances in the development,synthesis,application,and tentative mechanism of biochar-based SRFs.The development mainly undergoes three stages:(i)soil amendment using biochar,(ii)interactions between nutrients and biochar,and(iii)biochar-based SRFs.Various methods are proposed to improve the fertilizer efficiency of biochar,majorly including in-situ pyrolysis,co-pyrolysis,impregnation,encapsulation,and granulation.Considering the distinct features of different methods,the integrated methods are promising for fabricating effective biochar-based SRFs.The in-depth understanding of the mechanism of nutrient loading and slow release is discussed based on current knowledge.Additionally,the perspectives and challenges of the potential application of biochar-based SRFs are described.Knowledge surveyed from this review indicates that applying biochar-based SRFs is a viable way of promoting sustainable agriculture.
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.
