CeO_2-ZrO_2 mixed oxides are widely used in the three-way catalysts due to their unique reversible oxygen storage and release capacity. Large surface area, high oxygen storage capacity and good thermal stability of ce...CeO_2-ZrO_2 mixed oxides are widely used in the three-way catalysts due to their unique reversible oxygen storage and release capacity. Large surface area, high oxygen storage capacity and good thermal stability of cerium zirconium mixed oxides are the key properties for the automotive catalysts so as to meet the strict emission regulations. In this work, alumina modified CeZrLaNd mixed oxides were prepared by a co-precipitation method. The effects of moisture in precursor and inert N2 atmosphere during calcinations on the structure and properties were investigated by Brunauer-Emmett-Teller(BET) surface area measurements, X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), hydrogen temperature-programmed reduction(H_2-TPR), oxygen storage capacity(OSC), Raman spectroscopy, and X-ray photoelectron spectroscopy(XPS). The results show that the moisture in precursor during calcinations increases the crystal grain size of the cerium zirconium mixed oxides, improving the thermal stability. And the aged surface area of sample after being calcined at1000 ℃ for 4 h reaches 68.8 m^2/g(5.7% increase compared with the common sample). The inert N2 atmosphere endows a great pore-enlarging effect, which leads to high fresh surface area of 148.9 m2/g(13.5% increase compared with the common sample) and big pore volume of 0.5705 mL/g. The redox and oxygen storage capacity are also improved by inert N2 atmosphere with high OSC value of 241.06μmolO_2/g(41.3% increase compared with the common calcination), due to the abundant formation of the crystal defects and oxygen vacancies.展开更多
We proposed a good calcinations condition of the ZnO disk to control the crystallography and nanoparticles in ZnO disk. The crystallography of precursor powder and disk powder were analyzed by the X-ray diffraction (X...We proposed a good calcinations condition of the ZnO disk to control the crystallography and nanoparticles in ZnO disk. The crystallography of precursor powder and disk powder were analyzed by the X-ray diffraction (XRD). The mean nanoparticles of ZnO disk was determinate by XRD results and observed by scanning electron microscope. The temperature ranges of 400℃ to 650℃ in air for 30 minutes were used calcinations ZnO disk. These temperature can be controlled the single phase, lattice parameters, unit cell volume, crystalline size, d-value, texture coefficient and bond lengths of Zn–Zn, Zn–O and O–O which correspond significantly the hexagonal crystal structure. The nanoparticles were small changed mean of 76.59 nm at the calcinations temperature range.展开更多
Hydroxyapatite luminescent nanocrystallines doped with 6 mol.%Tb^(3+)(Tb-HA)were prepared via chemical deposition method and calcined at different temperature,and the effects of calcinations temperature on the lumines...Hydroxyapatite luminescent nanocrystallines doped with 6 mol.%Tb^(3+)(Tb-HA)were prepared via chemical deposition method and calcined at different temperature,and the effects of calcinations temperature on the luminescence intensity and fluorescent lifetime were studied.TEM image of Tb-HA revealed that the shape of nanocrystallines changed from needle-like to short rod-like and sphere-like with the increase of calcinations temperature;while the particles sizes decreased from 190 nm to 110 nm.the crystallinity degree increased.the typical emission peaks attributed to Tb^(3+) ions were observed in emission spectra of 6 mol.%Tb-HA under 378 nm excitation.the luminescent intensity of Tb-HA,which showed the fluorescence quenching,firstly enhanced and then decreased at 700℃;while the fluorescent lifetime increased firstly and then decreased after 600℃.Furthermore,the ratio of intensity between 545 nm and 490 nm corresponding to electric-dipole and magnetic-dipole transition(I_(R):I_(O))increases firstly and then decreases,which revealed that the proportion of substitute type and site of Ca^(2+) ions by Tb^(3+) ions were helpful to realize the substitute process and functional structure design.展开更多
Dye wastewater poses a significant threat to aquatic organisms due to its high toxicity.Reducing or eliminating the dye waste from the water is necessary for a healthy and sustainable aquaculture.This study investigat...Dye wastewater poses a significant threat to aquatic organisms due to its high toxicity.Reducing or eliminating the dye waste from the water is necessary for a healthy and sustainable aquaculture.This study investigated the adsorption properties of Congo red dye on Mytilus edulis shell powders prepared by calcination at 500℃,700℃,and 900℃.The modified shell powder products were analyzed by SEM(scanning eletron microscopy)and FTIR(fourier transform infrared spectroscopy)for the morphology and structural characterization.The effects of different calcination temperatures,reaction times,reaction temperatures,and initial concentration of Congo red on the adsorption properties were investigated.The adsorption kinetics and isothermal adsorption models were also established.The results revealed that the shell powder calcinated at 900℃showed the best adsorption capacity on Congo red from aqueous solution.The adsorption reaction reached equilibrium after 150 min and followed by the pseudo-second-order kinetic model.At 25℃,96.2%of the Congo red in the solution could be removed,and the adsorption capacity could reach at least 1015 mg g^(–1).The adsorption isotherm is fit with the Freundlich model,indicating a multiphase adsorption process.These results are helpful for cleaning and treating printing and dyeing effluents as well as high-value utilization of shell waste resources.展开更多
The effects of calcination temperature and mechanical ball milling on the physicochemical properties of electrolytic manganese residue(EMR),mineral phase transition,pozzolanic activity,and pore structure were studied....The effects of calcination temperature and mechanical ball milling on the physicochemical properties of electrolytic manganese residue(EMR),mineral phase transition,pozzolanic activity,and pore structure were studied.The experimental results show that the strength activity index(SAI)of 20%EMR mixed mortar at 28 days is 90.54%,95.40%,and 90.73%,respectively,after pretreatment with EMR at 800℃calcined for 3,5,and 8 min.This is mainly attributed to the high temperature decomposition of gypsum dihydrate to form activated calcium oxide.In addition,high temperature and mechanical force destroys the Si-O chemical bond and promotes the formation of calcium silicate gel structure.Due to the existence of a large number of gypsum phases in EMR mixed mortar,a large number of ettringite,C-S-H,aluminosilicate,C-A-S-H,and AFm are formed,which strongly verifies the volcanic activity of EMR.The leaching test shows that high temperature calcination has a significant effect on the stabilization of NH_(3)-N.However,the curing effect of Mn^(2+)is significant only in the calcination at 1000℃,but both Mn^(2+)and NH_(3)-N in the calcined EMR are higher than the emission standard.The encapsulation effect of EMR composite mortar provided by hydration products,and the buffering capacity of the Si-Al system for solidification of heavy metals and strong alkalis are conducive to the stability of Mn^(2+)and NH_(3)-N.After the EMR mixed mortar is aged for 3 days,Mn and NH_(3)-N are completely lower than the emission standard.In general,the EMR mixed mortar can meet the requirements for green building use.展开更多
Aceh in Indonesia is rich inmarine resources and abundant fishery products such as oyster.Traditionally,fishermen only harvest oysters and discard the shells,which can cause pollution and environmental contamination.W...Aceh in Indonesia is rich inmarine resources and abundant fishery products such as oyster.Traditionally,fishermen only harvest oysters and discard the shells,which can cause pollution and environmental contamination.Waste Oyster Shells(WOS)contain a high percentage of calcium carbonate(CaCO_(3))that experiences thermal decomposition at high temperature,following the reaction CaCO_(3)→CaO+CO_(2)(ΔT=825℃).At temperature>900℃,dead-burned lime is formed,which severely influences CaO reactivity.However,the optimum temperature for producing high CaO content is still uncertain.Therefore,this study aimed to determine the optimum calcination temperature to produce high CaO content,assess initial setting time of WOS paste,and identify the best compressive strength of paste.For the experiment,WOS was used as a partial cement replacement(with a size of 0.075 mm)in paste at a proportion of 5%and calcined at temperature of 700℃,800℃,900℃,and 1000℃.The specimens used were an ebonite ring(dimensions:70 mm bottom diameter,60 mm top diameter,and 40 mm height)and a cube(dimensions:5 cm×5 cm×5 cm).The experiment was conducted following the ASTM(American Society for Testing andMaterials)standards and optimumcompressive strength values were analyzed using ANOVA(Analysis of Variance)and Response Surface Methodology(RSM)through the Design Expert software.The results showed that WOS calcined at 1000℃ increased CaO content by approximately 57.40%.Furthermore,the initial setting time test of 5%WOS paste at 1000℃ showed a more uniform binding performance compared to conventional cement paste,with an initial setting time of 75 min and a penetration depth of 15 mm.In line with the analysis,optimum compressive strength of 71.028 MPa with a desirability value of 0.986 was achieved at 5%cement replacement and calcination temperature of 786.44℃.展开更多
To advance the precise regulation and high-value utilization of halloysite nanotubes(HNTs),this work systematically investigated five treatment strategies,including calcination,acid treatment,alkali treatment,acid tre...To advance the precise regulation and high-value utilization of halloysite nanotubes(HNTs),this work systematically investigated five treatment strategies,including calcination,acid treatment,alkali treatment,acid treatment of calcined HNTs,and alkali treatment of calcined HNTs,to modulate their structural and application properties.The structural characteristics,surface properties,and methylene blue(MB)adsorption capacity of HNTs under multiple treatments were systematically analyzed.Calcination at varying temperatures modified the crystal structure,morphology,and surface properties of HNTs,with higher calcination temperatures reducing their reactivity towards MB.Moderate acid treatment expanded the lumen and decreased the surface potential of HNTs,significantly enhancing MB adsorption capacity.In contrast,alkali treatment dispersed the multilayered walls of HNTs and raised surface potential,reducing MB affinity.Acid treatment of calcined HNTs effectively increased their specific surface areas by leaching most of Al while maintaining the tubular structure,thereby maximizing MB adsorption.Alkali treatment of calcined HNTs destroyed the tubular structure and resulted in poor MB adsorption.HNTs pre-calcined at 600℃ for 3 h and acid-treated at 60℃ for 8 h exhibited an optimal specific surface area of443 m^(2)·g^(-1)and an MB adsorption capacity of 190 mg·g^(-1).Kinetic and Arrhenius equation fittings indicated that chemical reactions control interactions of acids and alkalis with HNTs.This study provides a comprehensive comparison and analysis of five treatment methods,offering insights into regulating the structures and surface properties of HNTs by controlling the treatment condition,thereby laying a foundation for their efficient utilization in practical applications.展开更多
Cement production,while essential for global infrastructure,contributes significantly to carbon dioxide emissions,accounting for approximately 7%of total emissions.To mitigate these environmental impacts,flash calcina...Cement production,while essential for global infrastructure,contributes significantly to carbon dioxide emissions,accounting for approximately 7%of total emissions.To mitigate these environmental impacts,flash calcination of kaolinitic clays has been investigated as a sustainable alternative.This technique involves the rapid heating of clays,enabling their use as supplementary cementitious materials.The primary objective of this study was to modify the color of calcined clay in various atmospheres(oxidizing,inert,and reducing)to achieve a grayish tone similar to commercial cement while preserving its reactive properties.The experimental procedure employed a tubular reactor with precise control of gas flows(atmospheric air,nitrogen,and a carbon monoxide–nitrogen mixture).Physicochemical characterization of the raw clay was conducted before calcination,with analyses repeated on the calcined clays following experimentation.Results indicated that clay calcined in an oxidizing atmosphere acquired a reddish hue,attributed to the oxidation of iron in hematite.The Clay exhibited a pinkish tone in an inert atmosphere,while calcination in a reducing atmosphere yielded the desired grayish color.Regarding pozzolanic activity,clays calcined in oxidizing and inert atmospheres displayed robust strength,ranging from 82%to 87%.Calcination in a reducing atmosphere resulted in slightly lower strength,around 74%,likely due to the clay’s chemical composition and the calcination process,which affects compound formation and material reactivity.展开更多
The Ni-ZnFe_(2)O_(4)(NixZn_(1-x)Fe_(2)O_(4),x=0.4-0.7)spinel was synthesized using Zn2+extracted from electric arc furnace dust(EAFD),nickel chloride hexahydrate,and Fe^(3+)extracted from iron scale as raw materials.T...The Ni-ZnFe_(2)O_(4)(NixZn_(1-x)Fe_(2)O_(4),x=0.4-0.7)spinel was synthesized using Zn2+extracted from electric arc furnace dust(EAFD),nickel chloride hexahydrate,and Fe^(3+)extracted from iron scale as raw materials.The zinc was selectively extracted from EAFD using CaO roasting followed by NH_(4)Cl solution leaching.The ferric ion was leached from iron scale using HCl solution as acid lixiviant.The experimental results demonstrate a high level of efficiency in the extraction of zinc,with a rate of 97.5%,and the leaching rate of ferric ion is 96.89%.The composition of the leaching solution is primary zinc and iron with low calcium,which is beneficial to the preparation of spinel ferrite.The influence of Ni content(x)and calcination temperature on the synthesis and magnetic properties of NixZn_(1-x)Fe_(2)O_(4)compounds was investigated by X-ray diffraction,scanning electron microscopy,and vibrating sample magnetometry.The results revealed that both Ni content and calcination temperature significantly affect the synthesis and magnetic properties of spinel NixZn_(1-x)Fe_(2)O_(4).Under the conditions of Ni content set at x=0.6,calcination temperature of 1100℃,and a duration of 2 h,a spinel NixZn_(1-x)Fe_(2)O_(4)with high saturation magnetization(Ms=65.7 A m2 kg-1)and low coercivity(Hc=0.056 A m^(-1))was obtained.展开更多
Surface regulation is a crucial technique for improving catalytic performance in heterogeneous catalysis.Although perovskite oxides containing noble metals show good performance and excellent thermal stability,the enc...Surface regulation is a crucial technique for improving catalytic performance in heterogeneous catalysis.Although perovskite oxides containing noble metals show good performance and excellent thermal stability,the encapsulation of noble metals in perovskite lattice restricts the exposure/usage of active sites.Herein,a method of high-temperature calcination coupling with selective dissolution was adopted to tune the physicochemical environment on the LaPd_(0.1)Mn_(0.9)O_(3)catalyst surface.The X-ray diffraction(XRD)and Raman results reveal that more Pd species emerge on the surface by elevating the calcination temperature,resulting in improved catalytic toluene oxidation activity.A further acid-etching of the LPMO-900 catalyst can also boost catalytic performance,being attributed to the enhanced redox ability and abundant surface oxygen vacancies.In addition,the optimized catalyst also exhibits excellent resistance to sintering and water vapor.This study provides new avenues for the rational design of highly efficient perovskite-based catalysts.展开更多
Catalytic oxidation of soot is of great importance for emission control on diesel vehicles.In this work,a highly active Cs/Co/Ce-Sn catalyst was investigated for soot oxidation,and it was unexpectedly found that high-...Catalytic oxidation of soot is of great importance for emission control on diesel vehicles.In this work,a highly active Cs/Co/Ce-Sn catalyst was investigated for soot oxidation,and it was unexpectedly found that high-temperature calcination greatly improved the activity of the catalyst.When the calcination temperature was increased from 500℃ to 750℃,T_(50) decreased from 456.9℃ to 389.8℃ in a NO/O_(2)/H_(2)O/N_(2) atmosphere.Characterization results revealed that high-temperature calcination can promote the ability to transfer negative charge density from Cs to other metal cations in Cs/Co/Ce-Sn,which will facilitate the production of more oxygen defects and the generation of more surface-active oxygen species.Surfaceactive oxygen species are beneficial to the oxidation of NO to NO_(2),leading to the high yield of NO_(2) exploitation.Therefore,the Cs/Co/Ce-Sn catalyst calcined at 750℃ demonstrated higher activity than that calcined at 500℃.This work provides a pathway to prepare high efficiency catalysts for the removal of soot and significant insight into the effects of calcination on soot oxidation catalysts.展开更多
We focus on a novel and economical route for the synthesis of Si fertilizer via the calcination method using lithium pyroxene acid-leaching residues as the starting materials.The molar ratio of Si/K/Ca of 1:1.4:0.8,ca...We focus on a novel and economical route for the synthesis of Si fertilizer via the calcination method using lithium pyroxene acid-leaching residues as the starting materials.The molar ratio of Si/K/Ca of 1:1.4:0.8,calcination temperature of 900℃and calcination time of 120 min were identified as the optimal conditions to maximize the available Si content of the prepared Si fertilizer.The performance of the resulting product satisfies the Chinese agricultural standard for silica fertilizers,providing a new solution for the large-scale harmless and sustainable reuse of lithium pyroxene tailings.The X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR)characterization elucidated the formation mechanism of silica fertilizers,and identified KAlSiO_(4)and K_(4)CaSi_(3)O_(9)as the primary silicates products.Observation of the surface morphology of the samples was conducted by scanning electron microscopy(SEM)and X-ray energy dispersive spectrometry(EDS),and compositional analysis of the micro-regions.The acceleration action of CaCO_(3)in the decomposition process of lithium pyroxene acid-leaching residues was demonstrated by the thermogravimetry-differential scanning calorimetry(TG-DSC)test.Determination of heavy metal elements in Si fertilizer was performed by ICP-OES.Potting experiments confirmed that the best growth of pakchoi was achieved when 5 g·kg^(-1)of Si fertilizer was applied.These evidence suggests that the Si fertilizer prepared in this study is a promising candidate for a silica-supplemented soil.展开更多
High-plastic clays with significant volume change due to moisture variations present critical challenges to civil engineering structures.Limestone calcined clay cement(LC3),an innovative and sustainable hydraulic bind...High-plastic clays with significant volume change due to moisture variations present critical challenges to civil engineering structures.Limestone calcined clay cement(LC3),an innovative and sustainable hydraulic binder,demonstrates significant potential for improving the engineering characteristics of such soils.Nevertheless,the impact of LC3 on the physico-mechanical characteristics of treated soil under a cyclic wet-dry environment remains unclear.This study for the first time investigates LC3's impact on the long-term durability of treated high-plastic clays through comprehensive macro-micro testing including physical,mechanical,mineralogical,and microstructural investigations with an emphasis on wet-dry cycles.The results revealed that LC3 treatment exhibits significant resistance to wet-dry cycles by completely mitigating the swelling potential,and a considerable reduction in plasticity resulting in enhanced workability.The compressibility and shear strength parameters have been significantly improved to several orders of magnitude.However,after six wet-dry cycles,a slight to modest reduction is observed,but overall durability remains superior to untreated soil.Cohesive and structural bonding ratios quantitatively assessed the impact of wet-dry cycles emphasizing the advantage of LC3 treatment.According to mineralogical and microstructural evaluation,the mechanism behind the adverse effects of wet-dry cycles on the compressibility and strength behavior of LC3-treated soil is mainly attributed to:(1)weakening of CSH/C(A)SH and ettringite(AFt)phases by exhibiting lower peak intensities;and(2)larger pore spaces due to repeated wet-dry cycles.These findings highlight LC3's performance in enhancing the long-term behavior and resilience of treated soils in real-world scenarios,providing durable solutions for infrastructure challenges.展开更多
This study explores the controllable synthesis of CuAlO_(2) using copper hydroxide and pseudo-boehmite powders as raw materials via a simple solid-phase ball milling method,along with its catalytic performance investi...This study explores the controllable synthesis of CuAlO_(2) using copper hydroxide and pseudo-boehmite powders as raw materials via a simple solid-phase ball milling method,along with its catalytic performance investigation in methanol steam reforming(MSR).Various catalysts were prepared under different conditions,such as calcination temperature,calcination atmosphere,and heating rate.Characterization techniques including BET,XRD,XPS,SEM and H2-TPR were employed to analyze the samples.The results revealed significant effects of calcination temperature on the phase compositions,specific surface area,reduction performance,and surface properties of the CA-T catalysts.Based on the findings,a synthesis route of CuAlO_(2) via the solid-phase method was proposed,highlighting the importance of high calcination temperature,nitrogen atmosphere,and low heating rate for CuAlO_(2) formation.Catalytic evaluation data demonstrated that CuAlO_(2) could catalyze MSR without pre-reduction,with the catalytic performance of CA-T catalysts being notably influenced by calcination temperature.Among the prepared catalysts,the CA-1100 catalyst exhibited the highest catalytic activity and stability.The findings of this study might be useful for the further study of the catalytic material for sustained release catalysis,including the synthesis of catalytic materials and the regulation of sustained release catalytic performance.展开更多
The present study has proposed a compact process for the production of high-purity β-Ga_(2)O_(3)powder by simply using gallium metal and water as the raw materials.The process basically consists of two essential step...The present study has proposed a compact process for the production of high-purity β-Ga_(2)O_(3)powder by simply using gallium metal and water as the raw materials.The process basically consists of two essential steps including hydrothermal synthesis of Ga OOH and calcination of Ga OOH for the production of the target product of β-Ga_(2)O_(3).Thermodynamic evaluation and systematic experiments were conducted for process parameter optimization.X-ray diffractometer(XRD),scanning electron microscopy(SEM),thermogravimetryDdifferential scanning calorimetry(TG-DSC)and X-ray photoelectron spectroscopy(XPS)were utilized to clarify the reaction mechanisms of the hydrothermal synthesis and transformation of Ga OOH to β-Ga_(2)O_(3)by calcination.Chemical analysis of the final product of β-Ga_(2)O_(3)obtained under the optimal conditions was carried out with inductively coupled plasma mass spectrometry(ICP-MS),and the results showed that the contents of the representative impurities such as Ni,Cu,In,Mn,Co,Zn and Cr are obviously lower than the requirement of 5N β-Ga_(2)O_(3)standard,exhibiting excellent application prospect of the proposed process to produce high-purity β-Ga_(2)O_(3).展开更多
A simple and convenient preparation method with high catalytic reduction activity is crucial for the remediation of nitrate contamination.In this study,the innovation for fabricating a nanoelectrode was developed by c...A simple and convenient preparation method with high catalytic reduction activity is crucial for the remediation of nitrate contamination.In this study,the innovation for fabricating a nanoelectrode was developed by calcinating the anodized plate to alter the surface crystalline phase of the material.The prepared calcined Ti nanopores(TNPs)electrode could effectively remove up to 95.1%nitrate from simulated groundwater at 30 mA·cm^(-2)electrolysis for 90 min,while under the same conditions,the removal efficiency of nanoelectrode prepared by conventional methods was merely 52.5%.Scanning electron microscopy images indicated that the calcined TNP nanoelectrode was porous with different pore sizes.The higher nitrate removal efficiency of TNPs-500(95.1%)than TNPs-400(77.5%)and TNPs-550(93.4%)may resulted from the positive nonlinear response of the larger electrochemical active surface area,the improved electron transfer and suitable surface structure,and not the“anatase-torutile”of surface TiO_(2)nanotubes.After 90 min of electrolysis,using RuO_(2)as an anode and adding 0.3 g·L^(-1)NaCl solution,87.5%nitrate was removed,and the by-products(ammonia and nitrite)were negligible.Increased temperature and alkaline conditions can enhance the nitrate removal,while higher initial nitrate concentration only improved the nitrate removal slightly.Moreover,The TNPs-500 electrode also exhibited excellent nitrate removal performance in real groundwater with the efficiency at 82.9%and 92.1%after 90 and 120 min,which were 0.87(removal efficiency=95.1%),0.92(removal efficiency=100%)of the efficiency for simulated groundwater,indicating the widely applicable conditions of the TNPs-500 electrode.This approach of surface-bonded elements and structure modification through calcination significantly improves catalytic activity and will guide the simple designing of functional nanostructured electrodes with wide application conditions.展开更多
Although coal fly ash(CFA)contains a high content of rare earth elements(REEs),the related extraction methods have limitations because of their low efficiencies,high levels of energy consumption,and other drawbacks.To...Although coal fly ash(CFA)contains a high content of rare earth elements(REEs),the related extraction methods have limitations because of their low efficiencies,high levels of energy consumption,and other drawbacks.To address these problems,in this study,we examined the coextraction of REEs and Al_(2)O_(3)from two types of Al_(2)O_(3)-rich CFA,pulverized CFA(PCFA)and circulating fluidized bed fly ash(CFBFA)using low-temperature calcination in the presence of K_(2)S_(2)O_(7).The total REEs,heavy REEs(HREEs),and light REEs(LREEs)extraction efficiencies were determined using different K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratios and calcination temperatures and correlated with the Al_(2)O_(3) extraction efficiency using Pearson correlation coefficient analysis.The REEs are concentrated within CFA particles encapsulated in an aluminosilicate glass phase,and the REEs extraction efficiency is related to the form of Al in CFA.The extraction efficiencies of Al_(2)O_(3) and REEs increase as the K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratio and calcination temperature increase,and the extraction selectivity of the more industrially valuable HREEs from CFBFA is higher.At high K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratios,the extraction of REEs from PCFA is more efficient than that from CFBFA with the regeneration of the highly active Al-O-Si bonds in CFBFA.The Al_(2)O_(3) extraction efficiencies of PCFA as well as CFBFA correlate strongly with the total REEs,HREEs,and LREEs extraction efficiencies.The developed extraction technology has the potential to promote CFA valorization and expand REEs resources,thus mitigating the bottlenecks of REEs procurement.展开更多
By using high-alumina fly ash as raw material,a process was proposed for activating the fly ash with Na_(2)CO_(3)calcination and extracting aluminum from activated clinker with sulfuric acid leaching.The feasibility o...By using high-alumina fly ash as raw material,a process was proposed for activating the fly ash with Na_(2)CO_(3)calcination and extracting aluminum from activated clinker with sulfuric acid leaching.The feasibility of roasting process of activated fly ash by Na_(2)CO_(3)was discussed based on thermodynamic analysis.The experimental results showed that Na_(2)CO_(3)gradually reactes with mullite over 700 K to produce NaAlSiO_(4).The optimal process conditions for the activation stage are:a material ratio of 1:1 between sodium carbonate and fly ash,a calcination temperature of 900℃,and a calcination time of 2.5 hours.Under these conditions,the leaching rate of aluminum is 90.3%.By comparing the SEM and XRD analysis of raw and clinker materials,it could be concluded that the mullite phase of fly ash is almost completely destroyed and transformed into sodium aluminosilicate with good acid solubility.展开更多
Monochloroacetic acid(MCAA)is identified as a highly carcinogenic disinfection by-product in chlorinated drinking water.In this study,a series of CeO_(2)-supported Pd catalysts(Pd/MCeO_(2))were synthesized through one...Monochloroacetic acid(MCAA)is identified as a highly carcinogenic disinfection by-product in chlorinated drinking water.In this study,a series of CeO_(2)-supported Pd catalysts(Pd/MCeO_(2))were synthesized through one-step calcination of Pd-loaded Ce-UiO-66-BDC(CeMOF),and the liquid-phase catalytic hydrodechlorination of MCA A was explored using these catalysts.For comparison,Pd/CeO_(2)catalysts were additionally synthesized using the conventional impregnation method.The characterization results reveal that the catalysts exhibit strong metal-support interaction,leading to high Pd dispersion and Pd^(n+)content.Additionally,the calcination temperature significantly influences catalytic performance,with the catalyst calcined at 500℃(Pd/MCeO_(2)-500)demonstrating the highest catalytic activity and achieving complete dechlorination of MCA A within 50 min.Furthermore,it is found that the catalytic MCAA hydrodechlorination using the catalysts adheres to the Langmuir-Hinshelwood model.Accordingly,low reaction pH is favorable for the catalytic hydrodechlorination of MCAA,enhancing MCAA adsorption on the catalyst surface due to the electrostatic interaction between MCAA and the catalyst surface.Theoretical results suggest that the presence of Pd^(n+)efficiently facilitates MCAA adsorption and C-Cl cleavage,thus significantly enhancing the liquid-phase catalytic hydrodechlorination.展开更多
The substantial arsenic(As)content present in arsenic-containing bio-leaching residue(ABR)presents noteworthy environ-mental challenges attributable to its inherent instability and susceptibility to leaching.Given its...The substantial arsenic(As)content present in arsenic-containing bio-leaching residue(ABR)presents noteworthy environ-mental challenges attributable to its inherent instability and susceptibility to leaching.Given its elevated calcium sulfate content,ABR exhibits considerable promise for industrial applications.This study delved into the feasibility of utilizing ABR as a source of sulfates for producing super sulfated cement(SSC),offering an innovative binder for cemented paste backfill(CPB).Thermal treatment at varying temperatures of 150,350,600,and 800℃ was employed to modify ABR’s performance.The investigation encompassed the examination of phase transformations and alterations in the chemical composition of As within ABR.Subsequently,the hydration characteristics of SSC utilizing ABR,with or without thermal treatment,were studied,encompassing reaction kinetics,setting time,strength development,and microstructure.The findings revealed that thermal treatment changed the calcium sulfate structure in ABR,consequently impacting the resultant sample performance.Notably,calcination at 600℃ demonstrated optimal modification effects on both early and long-term strength attributes.This enhanced performance can be attributed to the augmented formation of reaction products and a densified micro-structure.Furthermore,the thermal treatment elicited modifications in the chemical As fractions within ABR,with limited impact on the As immobilization capacity of the prepared binders.展开更多
基金Project supported by the China National Key Research and Development Program(2017YFC0211002)
文摘CeO_2-ZrO_2 mixed oxides are widely used in the three-way catalysts due to their unique reversible oxygen storage and release capacity. Large surface area, high oxygen storage capacity and good thermal stability of cerium zirconium mixed oxides are the key properties for the automotive catalysts so as to meet the strict emission regulations. In this work, alumina modified CeZrLaNd mixed oxides were prepared by a co-precipitation method. The effects of moisture in precursor and inert N2 atmosphere during calcinations on the structure and properties were investigated by Brunauer-Emmett-Teller(BET) surface area measurements, X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), hydrogen temperature-programmed reduction(H_2-TPR), oxygen storage capacity(OSC), Raman spectroscopy, and X-ray photoelectron spectroscopy(XPS). The results show that the moisture in precursor during calcinations increases the crystal grain size of the cerium zirconium mixed oxides, improving the thermal stability. And the aged surface area of sample after being calcined at1000 ℃ for 4 h reaches 68.8 m^2/g(5.7% increase compared with the common sample). The inert N2 atmosphere endows a great pore-enlarging effect, which leads to high fresh surface area of 148.9 m2/g(13.5% increase compared with the common sample) and big pore volume of 0.5705 mL/g. The redox and oxygen storage capacity are also improved by inert N2 atmosphere with high OSC value of 241.06μmolO_2/g(41.3% increase compared with the common calcination), due to the abundant formation of the crystal defects and oxygen vacancies.
文摘We proposed a good calcinations condition of the ZnO disk to control the crystallography and nanoparticles in ZnO disk. The crystallography of precursor powder and disk powder were analyzed by the X-ray diffraction (XRD). The mean nanoparticles of ZnO disk was determinate by XRD results and observed by scanning electron microscope. The temperature ranges of 400℃ to 650℃ in air for 30 minutes were used calcinations ZnO disk. These temperature can be controlled the single phase, lattice parameters, unit cell volume, crystalline size, d-value, texture coefficient and bond lengths of Zn–Zn, Zn–O and O–O which correspond significantly the hexagonal crystal structure. The nanoparticles were small changed mean of 76.59 nm at the calcinations temperature range.
基金The authors gratefully acknowledge the financial support of International S&T Cooperation Program of China(No.2009DFR50520)Natural Science Foundation of China(NO.51472151).
文摘Hydroxyapatite luminescent nanocrystallines doped with 6 mol.%Tb^(3+)(Tb-HA)were prepared via chemical deposition method and calcined at different temperature,and the effects of calcinations temperature on the luminescence intensity and fluorescent lifetime were studied.TEM image of Tb-HA revealed that the shape of nanocrystallines changed from needle-like to short rod-like and sphere-like with the increase of calcinations temperature;while the particles sizes decreased from 190 nm to 110 nm.the crystallinity degree increased.the typical emission peaks attributed to Tb^(3+) ions were observed in emission spectra of 6 mol.%Tb-HA under 378 nm excitation.the luminescent intensity of Tb-HA,which showed the fluorescence quenching,firstly enhanced and then decreased at 700℃;while the fluorescent lifetime increased firstly and then decreased after 600℃.Furthermore,the ratio of intensity between 545 nm and 490 nm corresponding to electric-dipole and magnetic-dipole transition(I_(R):I_(O))increases firstly and then decreases,which revealed that the proportion of substitute type and site of Ca^(2+) ions by Tb^(3+) ions were helpful to realize the substitute process and functional structure design.
基金funded by the National Key Research and Development Program of China(No.2023YFD2401105)the Fujian Science and Technology Planning ProjectSTS Program(No.2021T3013)。
文摘Dye wastewater poses a significant threat to aquatic organisms due to its high toxicity.Reducing or eliminating the dye waste from the water is necessary for a healthy and sustainable aquaculture.This study investigated the adsorption properties of Congo red dye on Mytilus edulis shell powders prepared by calcination at 500℃,700℃,and 900℃.The modified shell powder products were analyzed by SEM(scanning eletron microscopy)and FTIR(fourier transform infrared spectroscopy)for the morphology and structural characterization.The effects of different calcination temperatures,reaction times,reaction temperatures,and initial concentration of Congo red on the adsorption properties were investigated.The adsorption kinetics and isothermal adsorption models were also established.The results revealed that the shell powder calcinated at 900℃showed the best adsorption capacity on Congo red from aqueous solution.The adsorption reaction reached equilibrium after 150 min and followed by the pseudo-second-order kinetic model.At 25℃,96.2%of the Congo red in the solution could be removed,and the adsorption capacity could reach at least 1015 mg g^(–1).The adsorption isotherm is fit with the Freundlich model,indicating a multiphase adsorption process.These results are helpful for cleaning and treating printing and dyeing effluents as well as high-value utilization of shell waste resources.
基金Funded by the National Natural Science Foundation of China(No.52178216)the Gansu Provincial Science and Technology Programme(No.23JRRA813)。
文摘The effects of calcination temperature and mechanical ball milling on the physicochemical properties of electrolytic manganese residue(EMR),mineral phase transition,pozzolanic activity,and pore structure were studied.The experimental results show that the strength activity index(SAI)of 20%EMR mixed mortar at 28 days is 90.54%,95.40%,and 90.73%,respectively,after pretreatment with EMR at 800℃calcined for 3,5,and 8 min.This is mainly attributed to the high temperature decomposition of gypsum dihydrate to form activated calcium oxide.In addition,high temperature and mechanical force destroys the Si-O chemical bond and promotes the formation of calcium silicate gel structure.Due to the existence of a large number of gypsum phases in EMR mixed mortar,a large number of ettringite,C-S-H,aluminosilicate,C-A-S-H,and AFm are formed,which strongly verifies the volcanic activity of EMR.The leaching test shows that high temperature calcination has a significant effect on the stabilization of NH_(3)-N.However,the curing effect of Mn^(2+)is significant only in the calcination at 1000℃,but both Mn^(2+)and NH_(3)-N in the calcined EMR are higher than the emission standard.The encapsulation effect of EMR composite mortar provided by hydration products,and the buffering capacity of the Si-Al system for solidification of heavy metals and strong alkalis are conducive to the stability of Mn^(2+)and NH_(3)-N.After the EMR mixed mortar is aged for 3 days,Mn and NH_(3)-N are completely lower than the emission standard.In general,the EMR mixed mortar can meet the requirements for green building use.
文摘Aceh in Indonesia is rich inmarine resources and abundant fishery products such as oyster.Traditionally,fishermen only harvest oysters and discard the shells,which can cause pollution and environmental contamination.Waste Oyster Shells(WOS)contain a high percentage of calcium carbonate(CaCO_(3))that experiences thermal decomposition at high temperature,following the reaction CaCO_(3)→CaO+CO_(2)(ΔT=825℃).At temperature>900℃,dead-burned lime is formed,which severely influences CaO reactivity.However,the optimum temperature for producing high CaO content is still uncertain.Therefore,this study aimed to determine the optimum calcination temperature to produce high CaO content,assess initial setting time of WOS paste,and identify the best compressive strength of paste.For the experiment,WOS was used as a partial cement replacement(with a size of 0.075 mm)in paste at a proportion of 5%and calcined at temperature of 700℃,800℃,900℃,and 1000℃.The specimens used were an ebonite ring(dimensions:70 mm bottom diameter,60 mm top diameter,and 40 mm height)and a cube(dimensions:5 cm×5 cm×5 cm).The experiment was conducted following the ASTM(American Society for Testing andMaterials)standards and optimumcompressive strength values were analyzed using ANOVA(Analysis of Variance)and Response Surface Methodology(RSM)through the Design Expert software.The results showed that WOS calcined at 1000℃ increased CaO content by approximately 57.40%.Furthermore,the initial setting time test of 5%WOS paste at 1000℃ showed a more uniform binding performance compared to conventional cement paste,with an initial setting time of 75 min and a penetration depth of 15 mm.In line with the analysis,optimum compressive strength of 71.028 MPa with a desirability value of 0.986 was achieved at 5%cement replacement and calcination temperature of 786.44℃.
基金Tural Science Foundation of China(No.52274255)the Young Scientists Fund of the National Natural ScienceFoundation of China(No.52404276)+3 种基金Fundamental Re-search Funds for the Central Universities,China(Nos.N2301003,N2201008,N2201004,and N2301025)Liaon-ingRevitalizationTalentsProgram,China(No.XLYC2202028)Postdoctoral Foundation of NortheasternUniversity,Young Elite Scientists Sponsorship Program byChina Association for Science and Technology(No.2022QNRC001)and China Postdoctoral Science Founda-tion(No.2022M720025)。
文摘To advance the precise regulation and high-value utilization of halloysite nanotubes(HNTs),this work systematically investigated five treatment strategies,including calcination,acid treatment,alkali treatment,acid treatment of calcined HNTs,and alkali treatment of calcined HNTs,to modulate their structural and application properties.The structural characteristics,surface properties,and methylene blue(MB)adsorption capacity of HNTs under multiple treatments were systematically analyzed.Calcination at varying temperatures modified the crystal structure,morphology,and surface properties of HNTs,with higher calcination temperatures reducing their reactivity towards MB.Moderate acid treatment expanded the lumen and decreased the surface potential of HNTs,significantly enhancing MB adsorption capacity.In contrast,alkali treatment dispersed the multilayered walls of HNTs and raised surface potential,reducing MB affinity.Acid treatment of calcined HNTs effectively increased their specific surface areas by leaching most of Al while maintaining the tubular structure,thereby maximizing MB adsorption.Alkali treatment of calcined HNTs destroyed the tubular structure and resulted in poor MB adsorption.HNTs pre-calcined at 600℃ for 3 h and acid-treated at 60℃ for 8 h exhibited an optimal specific surface area of443 m^(2)·g^(-1)and an MB adsorption capacity of 190 mg·g^(-1).Kinetic and Arrhenius equation fittings indicated that chemical reactions control interactions of acids and alkalis with HNTs.This study provides a comprehensive comparison and analysis of five treatment methods,offering insights into regulating the structures and surface properties of HNTs by controlling the treatment condition,thereby laying a foundation for their efficient utilization in practical applications.
基金financial support for the research and for the publication costs of the articlesupported by Santa Catarina State Research Support Foundation(FAPESC)National Council for Scientific and Technological Development(CNPq no 302903/2023-2).
文摘Cement production,while essential for global infrastructure,contributes significantly to carbon dioxide emissions,accounting for approximately 7%of total emissions.To mitigate these environmental impacts,flash calcination of kaolinitic clays has been investigated as a sustainable alternative.This technique involves the rapid heating of clays,enabling their use as supplementary cementitious materials.The primary objective of this study was to modify the color of calcined clay in various atmospheres(oxidizing,inert,and reducing)to achieve a grayish tone similar to commercial cement while preserving its reactive properties.The experimental procedure employed a tubular reactor with precise control of gas flows(atmospheric air,nitrogen,and a carbon monoxide–nitrogen mixture).Physicochemical characterization of the raw clay was conducted before calcination,with analyses repeated on the calcined clays following experimentation.Results indicated that clay calcined in an oxidizing atmosphere acquired a reddish hue,attributed to the oxidation of iron in hematite.The Clay exhibited a pinkish tone in an inert atmosphere,while calcination in a reducing atmosphere yielded the desired grayish color.Regarding pozzolanic activity,clays calcined in oxidizing and inert atmospheres displayed robust strength,ranging from 82%to 87%.Calcination in a reducing atmosphere resulted in slightly lower strength,around 74%,likely due to the clay’s chemical composition and the calcination process,which affects compound formation and material reactivity.
基金supported by the National Natural Science Foundation of China(No.52374344).
文摘The Ni-ZnFe_(2)O_(4)(NixZn_(1-x)Fe_(2)O_(4),x=0.4-0.7)spinel was synthesized using Zn2+extracted from electric arc furnace dust(EAFD),nickel chloride hexahydrate,and Fe^(3+)extracted from iron scale as raw materials.The zinc was selectively extracted from EAFD using CaO roasting followed by NH_(4)Cl solution leaching.The ferric ion was leached from iron scale using HCl solution as acid lixiviant.The experimental results demonstrate a high level of efficiency in the extraction of zinc,with a rate of 97.5%,and the leaching rate of ferric ion is 96.89%.The composition of the leaching solution is primary zinc and iron with low calcium,which is beneficial to the preparation of spinel ferrite.The influence of Ni content(x)and calcination temperature on the synthesis and magnetic properties of NixZn_(1-x)Fe_(2)O_(4)compounds was investigated by X-ray diffraction,scanning electron microscopy,and vibrating sample magnetometry.The results revealed that both Ni content and calcination temperature significantly affect the synthesis and magnetic properties of spinel NixZn_(1-x)Fe_(2)O_(4).Under the conditions of Ni content set at x=0.6,calcination temperature of 1100℃,and a duration of 2 h,a spinel NixZn_(1-x)Fe_(2)O_(4)with high saturation magnetization(Ms=65.7 A m2 kg-1)and low coercivity(Hc=0.056 A m^(-1))was obtained.
基金Project supported by the National Key R&D Program of China(2023YFC3710300)the National Natural Science Foundation of China(U23A2099,22276111)+1 种基金the Taishan Scholar Project of Shandong Province(202306031)the Natural Science Foundation of Shandong Province(2023HWYQ-024)。
文摘Surface regulation is a crucial technique for improving catalytic performance in heterogeneous catalysis.Although perovskite oxides containing noble metals show good performance and excellent thermal stability,the encapsulation of noble metals in perovskite lattice restricts the exposure/usage of active sites.Herein,a method of high-temperature calcination coupling with selective dissolution was adopted to tune the physicochemical environment on the LaPd_(0.1)Mn_(0.9)O_(3)catalyst surface.The X-ray diffraction(XRD)and Raman results reveal that more Pd species emerge on the surface by elevating the calcination temperature,resulting in improved catalytic toluene oxidation activity.A further acid-etching of the LPMO-900 catalyst can also boost catalytic performance,being attributed to the enhanced redox ability and abundant surface oxygen vacancies.In addition,the optimized catalyst also exhibits excellent resistance to sintering and water vapor.This study provides new avenues for the rational design of highly efficient perovskite-based catalysts.
基金supported by the National Natural Science Foundation of China(Nos.22206183,52225004)the National Key R&D Program of China(No.2022YFC3701804)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA23010201)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2022309)。
文摘Catalytic oxidation of soot is of great importance for emission control on diesel vehicles.In this work,a highly active Cs/Co/Ce-Sn catalyst was investigated for soot oxidation,and it was unexpectedly found that high-temperature calcination greatly improved the activity of the catalyst.When the calcination temperature was increased from 500℃ to 750℃,T_(50) decreased from 456.9℃ to 389.8℃ in a NO/O_(2)/H_(2)O/N_(2) atmosphere.Characterization results revealed that high-temperature calcination can promote the ability to transfer negative charge density from Cs to other metal cations in Cs/Co/Ce-Sn,which will facilitate the production of more oxygen defects and the generation of more surface-active oxygen species.Surfaceactive oxygen species are beneficial to the oxidation of NO to NO_(2),leading to the high yield of NO_(2) exploitation.Therefore,the Cs/Co/Ce-Sn catalyst calcined at 750℃ demonstrated higher activity than that calcined at 500℃.This work provides a pathway to prepare high efficiency catalysts for the removal of soot and significant insight into the effects of calcination on soot oxidation catalysts.
文摘We focus on a novel and economical route for the synthesis of Si fertilizer via the calcination method using lithium pyroxene acid-leaching residues as the starting materials.The molar ratio of Si/K/Ca of 1:1.4:0.8,calcination temperature of 900℃and calcination time of 120 min were identified as the optimal conditions to maximize the available Si content of the prepared Si fertilizer.The performance of the resulting product satisfies the Chinese agricultural standard for silica fertilizers,providing a new solution for the large-scale harmless and sustainable reuse of lithium pyroxene tailings.The X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR)characterization elucidated the formation mechanism of silica fertilizers,and identified KAlSiO_(4)and K_(4)CaSi_(3)O_(9)as the primary silicates products.Observation of the surface morphology of the samples was conducted by scanning electron microscopy(SEM)and X-ray energy dispersive spectrometry(EDS),and compositional analysis of the micro-regions.The acceleration action of CaCO_(3)in the decomposition process of lithium pyroxene acid-leaching residues was demonstrated by the thermogravimetry-differential scanning calorimetry(TG-DSC)test.Determination of heavy metal elements in Si fertilizer was performed by ICP-OES.Potting experiments confirmed that the best growth of pakchoi was achieved when 5 g·kg^(-1)of Si fertilizer was applied.These evidence suggests that the Si fertilizer prepared in this study is a promising candidate for a silica-supplemented soil.
基金The financial support of the National Natural Science Foundation of China(Grant No.42030714)the National Key R&D Program of China(Grant No.2019YFC1509900)is greatly acknowledged.
文摘High-plastic clays with significant volume change due to moisture variations present critical challenges to civil engineering structures.Limestone calcined clay cement(LC3),an innovative and sustainable hydraulic binder,demonstrates significant potential for improving the engineering characteristics of such soils.Nevertheless,the impact of LC3 on the physico-mechanical characteristics of treated soil under a cyclic wet-dry environment remains unclear.This study for the first time investigates LC3's impact on the long-term durability of treated high-plastic clays through comprehensive macro-micro testing including physical,mechanical,mineralogical,and microstructural investigations with an emphasis on wet-dry cycles.The results revealed that LC3 treatment exhibits significant resistance to wet-dry cycles by completely mitigating the swelling potential,and a considerable reduction in plasticity resulting in enhanced workability.The compressibility and shear strength parameters have been significantly improved to several orders of magnitude.However,after six wet-dry cycles,a slight to modest reduction is observed,but overall durability remains superior to untreated soil.Cohesive and structural bonding ratios quantitatively assessed the impact of wet-dry cycles emphasizing the advantage of LC3 treatment.According to mineralogical and microstructural evaluation,the mechanism behind the adverse effects of wet-dry cycles on the compressibility and strength behavior of LC3-treated soil is mainly attributed to:(1)weakening of CSH/C(A)SH and ettringite(AFt)phases by exhibiting lower peak intensities;and(2)larger pore spaces due to repeated wet-dry cycles.These findings highlight LC3's performance in enhancing the long-term behavior and resilience of treated soils in real-world scenarios,providing durable solutions for infrastructure challenges.
基金supported by the Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology(2023yjrc51)the National Natural Science Foundation of China(22172184)+2 种基金the Foundation of State Key Laboratory of Coal Conversion(J24-25-603)the Fundamental Research Project of ICC-CAS(SCJC-DT-2023-01)Weiqiao-UCAS Special Projects on Low-Carbon Technology Development(GYY-DTFZ-2022-015)。
文摘This study explores the controllable synthesis of CuAlO_(2) using copper hydroxide and pseudo-boehmite powders as raw materials via a simple solid-phase ball milling method,along with its catalytic performance investigation in methanol steam reforming(MSR).Various catalysts were prepared under different conditions,such as calcination temperature,calcination atmosphere,and heating rate.Characterization techniques including BET,XRD,XPS,SEM and H2-TPR were employed to analyze the samples.The results revealed significant effects of calcination temperature on the phase compositions,specific surface area,reduction performance,and surface properties of the CA-T catalysts.Based on the findings,a synthesis route of CuAlO_(2) via the solid-phase method was proposed,highlighting the importance of high calcination temperature,nitrogen atmosphere,and low heating rate for CuAlO_(2) formation.Catalytic evaluation data demonstrated that CuAlO_(2) could catalyze MSR without pre-reduction,with the catalytic performance of CA-T catalysts being notably influenced by calcination temperature.Among the prepared catalysts,the CA-1100 catalyst exhibited the highest catalytic activity and stability.The findings of this study might be useful for the further study of the catalytic material for sustained release catalysis,including the synthesis of catalytic materials and the regulation of sustained release catalytic performance.
基金supported by the National Natural Science Foundation of China(No.51904003)the Key Research and Development Plan of Anhui Province(No.2022n07020004)+1 种基金the Natural Science Foundation of Anhui Province(Nos.2308085ME156 and 2108085J26)Anhui Provincial Department of Education(No.2022AH050332)。
文摘The present study has proposed a compact process for the production of high-purity β-Ga_(2)O_(3)powder by simply using gallium metal and water as the raw materials.The process basically consists of two essential steps including hydrothermal synthesis of Ga OOH and calcination of Ga OOH for the production of the target product of β-Ga_(2)O_(3).Thermodynamic evaluation and systematic experiments were conducted for process parameter optimization.X-ray diffractometer(XRD),scanning electron microscopy(SEM),thermogravimetryDdifferential scanning calorimetry(TG-DSC)and X-ray photoelectron spectroscopy(XPS)were utilized to clarify the reaction mechanisms of the hydrothermal synthesis and transformation of Ga OOH to β-Ga_(2)O_(3)by calcination.Chemical analysis of the final product of β-Ga_(2)O_(3)obtained under the optimal conditions was carried out with inductively coupled plasma mass spectrometry(ICP-MS),and the results showed that the contents of the representative impurities such as Ni,Cu,In,Mn,Co,Zn and Cr are obviously lower than the requirement of 5N β-Ga_(2)O_(3)standard,exhibiting excellent application prospect of the proposed process to produce high-purity β-Ga_(2)O_(3).
基金supported by the Inner Mongolia Natural Science Foundation(2024MS02012)the College Students Innovation and Entrepreneurship Training Program(2024J00131)the Inner Mongolia Autonomous Region Education Science Research“14th Five-Year Plan”Project(NGJGH2022411).
文摘A simple and convenient preparation method with high catalytic reduction activity is crucial for the remediation of nitrate contamination.In this study,the innovation for fabricating a nanoelectrode was developed by calcinating the anodized plate to alter the surface crystalline phase of the material.The prepared calcined Ti nanopores(TNPs)electrode could effectively remove up to 95.1%nitrate from simulated groundwater at 30 mA·cm^(-2)electrolysis for 90 min,while under the same conditions,the removal efficiency of nanoelectrode prepared by conventional methods was merely 52.5%.Scanning electron microscopy images indicated that the calcined TNP nanoelectrode was porous with different pore sizes.The higher nitrate removal efficiency of TNPs-500(95.1%)than TNPs-400(77.5%)and TNPs-550(93.4%)may resulted from the positive nonlinear response of the larger electrochemical active surface area,the improved electron transfer and suitable surface structure,and not the“anatase-torutile”of surface TiO_(2)nanotubes.After 90 min of electrolysis,using RuO_(2)as an anode and adding 0.3 g·L^(-1)NaCl solution,87.5%nitrate was removed,and the by-products(ammonia and nitrite)were negligible.Increased temperature and alkaline conditions can enhance the nitrate removal,while higher initial nitrate concentration only improved the nitrate removal slightly.Moreover,The TNPs-500 electrode also exhibited excellent nitrate removal performance in real groundwater with the efficiency at 82.9%and 92.1%after 90 and 120 min,which were 0.87(removal efficiency=95.1%),0.92(removal efficiency=100%)of the efficiency for simulated groundwater,indicating the widely applicable conditions of the TNPs-500 electrode.This approach of surface-bonded elements and structure modification through calcination significantly improves catalytic activity and will guide the simple designing of functional nanostructured electrodes with wide application conditions.
基金Project supported by the Liaoning Education Department(LJKZ0348,LJKMZ20220682)Liaoning Science and Technology Department(2021JH1/10400018)the National Key Research and Development Program of China(2019YFC1803800)。
文摘Although coal fly ash(CFA)contains a high content of rare earth elements(REEs),the related extraction methods have limitations because of their low efficiencies,high levels of energy consumption,and other drawbacks.To address these problems,in this study,we examined the coextraction of REEs and Al_(2)O_(3)from two types of Al_(2)O_(3)-rich CFA,pulverized CFA(PCFA)and circulating fluidized bed fly ash(CFBFA)using low-temperature calcination in the presence of K_(2)S_(2)O_(7).The total REEs,heavy REEs(HREEs),and light REEs(LREEs)extraction efficiencies were determined using different K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratios and calcination temperatures and correlated with the Al_(2)O_(3) extraction efficiency using Pearson correlation coefficient analysis.The REEs are concentrated within CFA particles encapsulated in an aluminosilicate glass phase,and the REEs extraction efficiency is related to the form of Al in CFA.The extraction efficiencies of Al_(2)O_(3) and REEs increase as the K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratio and calcination temperature increase,and the extraction selectivity of the more industrially valuable HREEs from CFBFA is higher.At high K_(2)S_(2)O_(7)/Al_(2)O_(3) molar ratios,the extraction of REEs from PCFA is more efficient than that from CFBFA with the regeneration of the highly active Al-O-Si bonds in CFBFA.The Al_(2)O_(3) extraction efficiencies of PCFA as well as CFBFA correlate strongly with the total REEs,HREEs,and LREEs extraction efficiencies.The developed extraction technology has the potential to promote CFA valorization and expand REEs resources,thus mitigating the bottlenecks of REEs procurement.
基金Funded by the National Natural Science Foundation of China(No.U1710257)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2019L0656)+2 种基金the Doctoral Research Foundation of Taiyuan University of Science and Technology,China(No.20142001)the Open Foundation Program of Key Laboratory for Ecological Metallurgy of Multimetallic Mineral,Ministry of Education,China(No.2020003)the Supported by Fundamental Research Program of Shanxi Province,China(No.202103021224281)。
文摘By using high-alumina fly ash as raw material,a process was proposed for activating the fly ash with Na_(2)CO_(3)calcination and extracting aluminum from activated clinker with sulfuric acid leaching.The feasibility of roasting process of activated fly ash by Na_(2)CO_(3)was discussed based on thermodynamic analysis.The experimental results showed that Na_(2)CO_(3)gradually reactes with mullite over 700 K to produce NaAlSiO_(4).The optimal process conditions for the activation stage are:a material ratio of 1:1 between sodium carbonate and fly ash,a calcination temperature of 900℃,and a calcination time of 2.5 hours.Under these conditions,the leaching rate of aluminum is 90.3%.By comparing the SEM and XRD analysis of raw and clinker materials,it could be concluded that the mullite phase of fly ash is almost completely destroyed and transformed into sodium aluminosilicate with good acid solubility.
基金financially supported by the National Natural Science Foundation of China(Nos.21976086 and 22002059)。
文摘Monochloroacetic acid(MCAA)is identified as a highly carcinogenic disinfection by-product in chlorinated drinking water.In this study,a series of CeO_(2)-supported Pd catalysts(Pd/MCeO_(2))were synthesized through one-step calcination of Pd-loaded Ce-UiO-66-BDC(CeMOF),and the liquid-phase catalytic hydrodechlorination of MCA A was explored using these catalysts.For comparison,Pd/CeO_(2)catalysts were additionally synthesized using the conventional impregnation method.The characterization results reveal that the catalysts exhibit strong metal-support interaction,leading to high Pd dispersion and Pd^(n+)content.Additionally,the calcination temperature significantly influences catalytic performance,with the catalyst calcined at 500℃(Pd/MCeO_(2)-500)demonstrating the highest catalytic activity and achieving complete dechlorination of MCA A within 50 min.Furthermore,it is found that the catalytic MCAA hydrodechlorination using the catalysts adheres to the Langmuir-Hinshelwood model.Accordingly,low reaction pH is favorable for the catalytic hydrodechlorination of MCAA,enhancing MCAA adsorption on the catalyst surface due to the electrostatic interaction between MCAA and the catalyst surface.Theoretical results suggest that the presence of Pd^(n+)efficiently facilitates MCAA adsorption and C-Cl cleavage,thus significantly enhancing the liquid-phase catalytic hydrodechlorination.
基金supported from the National Natural Science Foundation of China(No.52304148)the Youth Project of Shanxi Basic Research Program,China(No.202203021212262).
文摘The substantial arsenic(As)content present in arsenic-containing bio-leaching residue(ABR)presents noteworthy environ-mental challenges attributable to its inherent instability and susceptibility to leaching.Given its elevated calcium sulfate content,ABR exhibits considerable promise for industrial applications.This study delved into the feasibility of utilizing ABR as a source of sulfates for producing super sulfated cement(SSC),offering an innovative binder for cemented paste backfill(CPB).Thermal treatment at varying temperatures of 150,350,600,and 800℃ was employed to modify ABR’s performance.The investigation encompassed the examination of phase transformations and alterations in the chemical composition of As within ABR.Subsequently,the hydration characteristics of SSC utilizing ABR,with or without thermal treatment,were studied,encompassing reaction kinetics,setting time,strength development,and microstructure.The findings revealed that thermal treatment changed the calcium sulfate structure in ABR,consequently impacting the resultant sample performance.Notably,calcination at 600℃ demonstrated optimal modification effects on both early and long-term strength attributes.This enhanced performance can be attributed to the augmented formation of reaction products and a densified micro-structure.Furthermore,the thermal treatment elicited modifications in the chemical As fractions within ABR,with limited impact on the As immobilization capacity of the prepared binders.
