Despite the intriguing merits of lithium-sulfur(Li-S) systems, they still suffer from the notorious‘‘shuttling-effect" of polysulfides. Herein, carbon materials with rational tailoring of morphology and pores w...Despite the intriguing merits of lithium-sulfur(Li-S) systems, they still suffer from the notorious‘‘shuttling-effect" of polysulfides. Herein, carbon materials with rational tailoring of morphology and pores were designed for strong loading/adsorption with the controlling of energy-storage ability.Through rational tailoring, it is strongly verified that such engineering of evolutions result in variational of sulfur immobilization in the obtained carbon. As expected, the targeted sample delivers a stable capacity of 925 m Ah g^(-1) after 100 loops. Supporting by the "cutting-off" manners, it is disclosed that mesopores in carbon possess more fascinated traits than micro/macropores in improving the utilization of sulfur and restraining Li_(2)S_x(4≤x≤8). Moreover, the long-chain polysulfide could be further consolidated by auto-doping oxygen groups. Supported by in-depth kinetic analysis, it is confirmed that the kinetics of ion/e-transfer during charging and discharging could be accelerated by mesopores, especially in stages of the formation of solid S_(8) and Li_(2)S, further improving the capacity of ion-storage in Li-S battery. Given this, the elaborate study provide significant insights into the effect of pore structure on kinetic performance about Li-storage behaviors in Li-S battery, and give guidance for improving sulfur immobilization.展开更多
A series of novel Ni/CeOe-Al2O3 composite catalysts were synthesized by one-step citric acid complex method, The as-synthesized catalysts were characterized by N2 physical adsorption/desorption, X-ray diffraction （XR...A series of novel Ni/CeOe-Al2O3 composite catalysts were synthesized by one-step citric acid complex method, The as-synthesized catalysts were characterized by N2 physical adsorption/desorption, X-ray diffraction （XRD）, Fourier transform infrared （FT-IR） spectroscopy, hydrogen temperature-programmed reduction （Hz-TPR）, X-ray photoelectron spectroscopy （XPS） and thermogravimetry analysis （TGA）. The effects of nickel content, calcination and reaction temperatures, gas hourly space velocity （GHSV） and inert gas dilution of N2 on their performance of catalytic partial oxidation of methane （CPOM） were investigated. Catalytic activity test results show that the highest methane conversion （〉85%）, the best selectivities to carbon monoxide （〉87%） and to hydrogen （〉95%）, the excellent stability and perfect Hz/CO ratio （2.0） can be obtained over Ni/CeO2-Al2O3 with 8 wt% Ni content calcined at 700 ℃ under the reaction condition of 750 ℃, CH4/O2 ratio of 2 ： 1 and gas hourly space velocity of 12000 mL.h-1 .g-1. Characterization results show that the good catalytic performance of this composite catalyst can be contributed to its large specific surface area （~108 m2.g-1）, small crystallite size, easy reducibility and low coking rate.展开更多
The electronic structure, cohesive energy and interfacial energy of ferrite（100）/NbC（100） and TiC（100）/NbC（100） interfaces have been investigated by the first-principles calculation. Moreover, the heterogeneou...The electronic structure, cohesive energy and interfacial energy of ferrite（100）/NbC（100） and TiC（100）/NbC（100） interfaces have been investigated by the first-principles calculation. Moreover, the heterogeneous nuclei mechanism of NbC particle was also analyzed. The results showed that the stacking sequences have a great influence on the cohesive energy and equilibrium interfacial separation of the abovementioned interfaces. Compared with C-terminated interfaces, the cohesive energy of Nb-terminated ones is lower while the equilibrium interface distance is larger. Among the two C-terminated interface structures, the interfacial energy between the NbC and ferrite is 4.54 J/m^2, which is larger than that of NbC/TiC interface（1.80 J/m^2）. Therefore, NbC particles prefer heterogeneous nucleation on TiC particles surface rather than the ferrite matrix, which agrees well with the experimental result.展开更多
Objective It is imperative to provide some consistent experimental results for the extraction of flavonid from Fructus Gardeniae. Methods The key extraction parameters that influenced the yield of flavonid from Fructu...Objective It is imperative to provide some consistent experimental results for the extraction of flavonid from Fructus Gardeniae. Methods The key extraction parameters that influenced the yield of flavonid from Fructus Gardeniae were optimized by employing an orthogonal experiment [L9（3）4], including the ratio of buffer solution （Na2B4O7· 10H2O） to raw material, concentration of Fructus Gardeniae in extracting solution, extraction time and pH of buffer solution. An UV/Vis detector was used to perform the qualitative and quantitative analyses of the extracted flavonid with the using of the standard sample. Results The maximum extraction yield of the crude extract was 5.0533 （mg/g） after 20 min when the mass ratio of Na2B4O7 · 10H2O to raw material was 0.4%, the concentration of Fructus Gardeniae in the extraction solution was 1/12 （g/mL）, and pH of buffer solution was 4.5. The positive reactions to the Molish and HCI-Mg tests suggested that the extracted compound was flavonoid, and FTIR measurements also identified the presence of flavonoid in the extracts. Conclusion This work is expected to provide a basis for further research, development, and utilization of Fructus gardenia in flavonid extraction.展开更多
Currently,air pollution is being exacerbated by rapid social,economic,and industrial development.Major air pollutants include volatile organic compounds(VOCs)and CO.Photocatalytic and thermocatalytic technology can be...Currently,air pollution is being exacerbated by rapid social,economic,and industrial development.Major air pollutants include volatile organic compounds(VOCs)and CO.Photocatalytic and thermocatalytic technology can be used to convert VOCs and CO into harmless gases effectively.Recently,photothermal synergistic catalysis has aroused much attention because of its higher performance than those of individual photocatalytic and thermocatalytic processes.There have been many reviews on separate photocatalysts and thermocatalysts for the treatment of VOCs and CO,but few reviews have focused on photothermal synergistic catalysis.In this minireview,we concentrate on recent progress into photothermal synergistic catalysis for the efficient removal of VOCs and CO.The treatment of typical VOCs(such as benzene,toluene,ethanol,formaldehyde,acetone,propylene,and propane)and CO are summarized and analyzed.Furthermore,we discuss the use of conventional reactor technology,such as fixed‐bed quartz reactors,for VOCs and CO removal.We also discuss the mechanism of the photothermal synergistic catalytic removal of VOCs and CO.Finally,we present perspectives for the photothermal synergistic catalytic removal of VOCs and CO.展开更多
Semiconductor photocatalysts are extensively applied in environmental treatment and energy conversion.However,one of their major disadvantages is their relatively low photocatalytic performance owing to the recombinat...Semiconductor photocatalysts are extensively applied in environmental treatment and energy conversion.However,one of their major disadvantages is their relatively low photocatalytic performance owing to the recombination of generated electron-hole pairs.The presence of the phase junction is an effective way to promote the photocatalytic activity by increasing the separation efficiency of the electron-hole pairs.Accordingly,extensive research has been conducted on the design of phase junctions of photocatalysts to improve their charge transfer properties and efficiencies.Therefore,for the design of an appropriate phase junction and the understanding of the mechanism of electron-hole separation,the development of the photocatalytic phase junction,including the preparation methods of the heterogeneous materials,is tremendously important and helpful.Herein,the commonly used,externally induced phase transformation fabrication techniques and the primary components of the semiconductors are reviewed.Future directions will still focus on the design and optimization of the phase junction of photocatalytic materials according to the phase transition with higher efficiencies for broadband responses and solar energy utilization.Additionally,the most popular phase transformation fabrication techniques of phase junctions are briefly reviewed from the application viewpoint.展开更多
A series of N‐CQDs/Ag2CO3composite crystals(where N‐CQDs=Nitrogen doped carbon quantumdots)were prepared by adding different volumes of a solution of N‐CQDs during Ag2CO3crystalgrowth.Under irradiation from a350‐W...A series of N‐CQDs/Ag2CO3composite crystals(where N‐CQDs=Nitrogen doped carbon quantumdots)were prepared by adding different volumes of a solution of N‐CQDs during Ag2CO3crystalgrowth.Under irradiation from a350‐W Xe lamp light(with optical filter,λ≥420nm),the performanceof N‐CQDs/Ag2CO3in photocatalytic degradation of phenol was evaluated.The as‐preparedsamples were analyzed by XRD,SEM,TEM,BET,element mapping,UV‐vis DRS,FT‐IR,XPS,transientphotocurrent response and EIS testing.The results showed that after coupling with trace amountsof N‐CQDs,both the photocatalytic activity and stability of Ag2CO3were greatly boosted.The additionof N‐CQDs solution influenced the crystallization of Ag2CO3,resulting in a distinct decrease inAg2CO3crystal size and an obvious increase in surface area.Moreover,the charge transfer resistancewas greatly reduced,and the separation efficiency of photogenerated electrons and holes wasstrongly promoted.The presence of NCQDs on the surface of the catalysts facilitates the transfer ofphotogenerated electrons,slowing the photocorrosion rate of Ag2CO3,and then resulting in higherstability than bare Ag2CO3in degradation.The synergistic effect of the improvement of morphologyand charge transfer rate thus accounted for the superior photocatalytic performance ofN‐CQDs/Ag2CO3.展开更多
A dual functional coordination polymer, namely, {[Tb（mat）（1.5）H2O]·2.5H2O}n（1, H2mta = 2-methoxyterephthalic acid）, was synthesized under solvothermal condition and characterized by single-crystal X-ray dif...A dual functional coordination polymer, namely, {[Tb（mat）（1.5）H2O]·2.5H2O}n（1, H2mta = 2-methoxyterephthalic acid）, was synthesized under solvothermal condition and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, X-ray powder diffraction analysis（PXRD）, and thermogravimetric analysis（TGA）. Complex 1 exhibits a 3D framework based on infinite rod-shaped secondary building units（SBUs）. Furthermore, the solid-state luminescent property and magnetic properties of the complex were investigated at room temperature; the results show that the complex exhibits excellent luminescent properties in green luminescence and weak antiferromagentic behavior.展开更多
CaMg(CO3)2microspheres were prepared and used as hard templates to fabricate a series of CaMg(CO3)2@Ag2CO3composite microspheres via a fast and low‐cost ion exchange process.The effects of ion exchange time and tempe...CaMg(CO3)2microspheres were prepared and used as hard templates to fabricate a series of CaMg(CO3)2@Ag2CO3composite microspheres via a fast and low‐cost ion exchange process.The effects of ion exchange time and temperature on the physicochemical properties and photocatalytic activities of the composite microspheres were studied through photocatalytic degradation of Acid Orange II under xenon lamp irradiation.The obtained samples were analyzed by X‐ray diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy,UV‐vis diffuse reflectance spectroscopy,N2physical adsorption,and photocurrent tests.The CaMg(CO3)2@Ag2CO3sample with the highest activity was obtained with an ion exchange time of4h and temperature of40°C.The degradation rate of Acid Orange II by this sample reached83.3%after15min of light irradiation,and the sample also performed well in phenol degradation.The CaMg(CO3)2@Ag2CO3produced under these ion exchange conditions showed a well‐ordered hierarchical morphology with small particle sizes,which was beneficial to light absorption and the transfer of photoelectrons(e-)and holes(h+)to the catalyst surface.Moreover,the separation of photogenerated carriers over the composites was greatly improved relative to bare CaMg(CO3)2.Despite the very low content of Ag2CO3(2.56%),excellent photocatalytic performance was obtained over the CaMg(CO3)2@Ag2CO3microspheres.展开更多
Photocatalytic water splitting has increasingly attracted attention as one of the most useful methods of converting solar energy into chemical fuel.However,the undesirable reverse reaction significantly limits the enh...Photocatalytic water splitting has increasingly attracted attention as one of the most useful methods of converting solar energy into chemical fuel.However,the undesirable reverse reaction significantly limits the enhancement of efficiency.Herein,we fabricated an Au nanorods/TiO2 nanodumbbells structure photocatalyst(Au NRs/TiO2 NDs)via a facile synthetic strategy,which has spatially separated oxidation and reduction reaction zones.Owing to the unique structure,the charge separation of these photocatalysts can be significantly improved and the reverse reaction can be efficiently inhibited.The photogenerated electrons were injected from the TiO2 to the Au NRs,and a positively charged TiO2 region and negatively charged Au region were formed under UV irradiation.An enhanced hydrogen production performance was obtained compared with that seen in normal Au-TiO2 heterostructure.Under optimized conditions,the H2-production rate can reach up to 60,264μmol/g/h,about six times higher than previously reported Au/TiO2 photocatalysts.Besides this,our work also demonstrates the key factors of precise synthesis of the Au NRs/TiO2 NDs structure,which provides a new perspective and experience for the design of similar catalysts.展开更多
This paper presents a description of the river terrace at Tangjia Village in Lhasa, Tibet. Selected types of phytolith and pollen were used as proxies to study the paleoclimate in the study area. Ancient climate and v...This paper presents a description of the river terrace at Tangjia Village in Lhasa, Tibet. Selected types of phytolith and pollen were used as proxies to study the paleoclimate in the study area. Ancient climate and vegetation changes since 10 ka BP were examined. The results demonstrated that between 10.2 and 8.9 ka BP, the dominating phytolith was the cold type and the dominating vegetation type was grassland-forest. This indicated that the climate changed from cool-humid to cool-dry and later turned back into a cool-humid climate. Between 8.9 and 8.1 ka BP, the main types of phytoliths were tooth, dumbbell, and polyhedral. This suggests that the vegetation consisted of forest-grassland and the period＇s climate had become warmer. Between 8.1 and 6.7 ka BP, the warm index of phytolith assembelage gradually increased, whereas the spore and pollen assembelage revealed that the vegetation was forest with hardwood. This suggested that the paleoclimate was warmest in this period. The herbaceous vegetation increased gradually, indicating that the climate had become colder since 7.5 ka BP. Between 6.7 and 4.6 ka BP, cold type phytolith such as tooth and cap were found. Simultaneously, the pollen assembelage indicated that the vegetation shifted from grassland to forest and then turned back into grassland. This implies that the climate fluctuated from cold-dry to cool- humid. Between 4.6 and 1.9 ka BP, the dominate type of phytolith was cold type and its warm index was in the range 0.04-0.28, suggesting a herbaceous vegetation cover and indicating that the climate was cold. The phytolith warm index from 1.9 ka BP revealed that the climate was continuously decreasing, and most of the pollen assembelage consisted of Chenopodiaceae and Artemisia. This conclusion is in agreement with the phytolith result that indicates that the climate was becoming colder and colder.展开更多
Thanks to tunable physical and chemical properties,two-dimensional(2D)materials have received intensive interest,endowing their excellent electrocatalytic performances for applications in energy conversion.However,the...Thanks to tunable physical and chemical properties,two-dimensional(2D)materials have received intensive interest,endowing their excellent electrocatalytic performances for applications in energy conversion.However,their catalytic activities are largely determined by poor adsorption energy and limited active edge sites.Herein,a one-step electrochemical exfoliation strategy was developed to fabricate 2D Ni-doped MoS_(2)nanosheets(Ni-EX-MoS_(2))with a lateral size of500 nm and thickness of3.5 nm.Profiting from high electrical conductivity and abundant exposing active sites,Ni-EX-MoS_(2)catalyst displayed an admirable performance for electrochemical hydrogen evolution reaction(HER)with a low overpotential of 145 m V at 10 m A/cm^(2)as well as a small Tafel slope of 89 m V/dec in alkaline media,which are superior to those of the most reported MoS_(2)-based electrocatalysts.The formed Ni species with tuning electronic structure played a crucial role as primary active center of Ni-EX-MoS_(2),as well as the forming stable 1T/2H phase MoS_(2)interface demonstrated a synergistic effect on electrocatalytic HER performance.Further,Ni-EX-MoS_(2)was employed as a cathode electrode for alkaline Zn-H_(2)O battery,which displayed a high power density of 3.3 m W/cm^(2)with excellent stability.This work will provide a simple and effective guideline for design of electrochemically exfoliated transition metal-doped MoS_(2)nanosheets to inspire their practical applications in energy catalytic and storage.展开更多
Ni-W-GO composite coatings were successfully plated on 45# steel substrate by co-electrodeposition technique in a Ni-W electrolyte solution, with different contents of graphene oxide (GO) nanoparticles in suspen? sion...Ni-W-GO composite coatings were successfully plated on 45# steel substrate by co-electrodeposition technique in a Ni-W electrolyte solution, with different contents of graphene oxide (GO) nanoparticles in suspen? sion. The structure, phase composition and surface morphology of as-plated composite coatings were characterized by Raman, X-ray diffraction (XRD), scanning electron microscopy (SEM) attached with energy disperse spectroscopy (EDS), respectively. The hardness and tribological behavior of the present coatings were also evaluated by Vickers Hardness tester and high-speed reciprocating friction and wear tester, and the wear mechanism was discussed as well. The results show that layer-structured GO nanoparticles significantly affect the microstructure and grain size of the Ni-W-GO composite coatings. Meanwhile, GO nanoparticles embedded in Ni- W-GO coatings can obviously improve the hardness and wear resistance in comparison with the corresp on ding Ni- W coatings. The highest microhardness and wear resistance of Ni-W-GO composite coatings are obtained with 0.15 g·L^-1 GO employing.展开更多
Nanofiber membranes from the composite of cellulose acetate/polyvinylpyrrolidone were prepared using electrospinning technique. After treated with water and alcoholic KOH to remove partially polyvinylpyrrolidone and d...Nanofiber membranes from the composite of cellulose acetate/polyvinylpyrrolidone were prepared using electrospinning technique. After treated with water and alcoholic KOH to remove partially polyvinylpyrrolidone and deacetylate the cellulose acetate, the membranes were further functionalized with thiol groups using thioglycolic acid. Related materials were characterized using infrared and thermogravimetric analysis. And the results showed that the membranes were success of functionalisation. Then the nanofiber membranes were used in the sorption-desorption process. The effects of pH, contacting time and adsorption capacity of nanofiber membranes were studied against Cu（II）, Cd（II） and Pb（II） ions. And the maximum adsorption capacities of Pb （II）, Cu （II）, and Cd （II） ions were estimated at 30.96, 19.63, 34.70 mg g-1. Our results suggested that the adsorption be- haviour of metal ions could be described using Langmuir model. Their adsorption kinetics was in agreement with the model of pseudo-second order, suggesting chemical adsorption as the rate-limiting step of the adsorption mechanism. The durability of the thiol-functionalized cellulose nanofiber membranes was also evaluated by repetitive adsorption-desorption.展开更多
A series of Mo-doped ZnO photocatalysts with different Mo-dopant concentrations have been prepared by a grind- ing-calcination method. The structure of these photocatalysts was characterized by a variety of methods, i...A series of Mo-doped ZnO photocatalysts with different Mo-dopant concentrations have been prepared by a grind- ing-calcination method. The structure of these photocatalysts was characterized by a variety of methods, including N2 physical adsorption, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared （FT-IR） spectroscopy, photoluminescence （PL） emission spectroscopy, and UV-vis diffuse reflectance spectroscopy （DRS）. It was found that Mo6＋ could enter into the crystal lattice of ZnO due to the radius of MO6＋ （0.065 nm） being smaller than that of Zn2＋ （0.083 nm）. XRD results indicated that Mo6＋ suppressed the growth of ZnO crystals. The FT-IR spectroscopy results showed that the ZnO with 2 wt.% Mo-doping has a higher level of surface hydroxyl groups than pure ZnO. PL spectroscopy indicated that ZnO with 2 wt.% Mo-doping also exhibited the largest reduction in the intensity of the emission peak at 390 nm caused by the recombi- nation of photogenerated hole-electron pairs. The activities of the Mo-doped ZnO photocatalysts were investigated in the pho- tocatalytic degradation of acid orange II under UV light （2 = 365 nm） irradiation. It was found that ZnO with 2 wt.% Mo-doping showed much higher photocatalytic activity and stability than pure ZnO. The high photocatalytic performance of the Mo-doped ZnO can be attributed to a great improvement in the surface properties of ZnO, higher crystallinity and lower recombination rate of photogenerated hole-electron （e-/h＋） pairs. Moreover, the undoped Mo species may exist in the form of MoO3 and form MoO3/ZnO heterojunctions which further favors the separation of e/h＋ pairs.展开更多
Extraction and separation of yttrium in chloride medium using tri-n-octylmethylammonium（2-sec-octylphenoxy） acetate（[N（1888）][SOPAA]） as an extractant were studied in this article. Tri-n-butyl phosphate（TBP） w...Extraction and separation of yttrium in chloride medium using tri-n-octylmethylammonium（2-sec-octylphenoxy） acetate（[N（1888）][SOPAA]） as an extractant were studied in this article. Tri-n-butyl phosphate（TBP） was used as a phase modifier to accelerate phase separation and improve the stability of organic phase. The addition of TBP contributed to shortening phase separation time, increasing extraction capacity of rare earth elements（REEs） and decreasing viscosity of organic phase. The slope analysis method and infrared spectroscopy were conducted to investigate the ion-association extraction mechanisms. Extraction and stripping performances of the different systems were also compared. The article showed that the extraction performance of mixed [N（1888）][SOPAA] and TBP is superior to that of [N（1888）][SOPAA] for heavy rare earth element（HREE）.展开更多
The reduction of zinc and iron oxides from electric arc furnace dust （EAFD） by carbon was investigated at temperatures between 800 and 1300℃. The analytic technique employed includes chemical analysis, X-ray fluore...The reduction of zinc and iron oxides from electric arc furnace dust （EAFD） by carbon was investigated at temperatures between 800 and 1300℃. The analytic technique employed includes chemical analysis, X-ray fluores- cence spectroscopy （XRF）, X-ray powder diffraction （XRD）, scanning electron microscopy （SEM） equipped with X-ray energy dispersive spectrometry （EDS）, and thermodynamic database FactSage 6.2. It was found that the reduction of zinc and iron oxides depends largely on Boudouad reaction. At 900℃, zinc exists in tested samples as ZnO, which is reduced in the temperature range of 1000--1 100℃. At 1 100℃, 99.11% of the zinc is evaporated. The metallization ratio of Fe is 79.19% at 1300℃, as the content of Fe2＋ is still 9.40%. A higher temperature is thus required for a higher reduction degree of Fe oxides by solid or gaseous carbon.展开更多
The leaching of chromium from stainless steel dust （SSD） is deleterious to the environment. To address this issue, the reduction of SSD briquettes can be employed to effectively extract chromium. The recovery rates ...The leaching of chromium from stainless steel dust （SSD） is deleterious to the environment. To address this issue, the reduction of SSD briquettes can be employed to effectively extract chromium. The recovery rates of iron, chromium, and nickel via ironbath reduction of SSD briquettes were determined using X-ray fluorescence spectroscopy, X-ray diffraction, and scanning electron microscopy measurements. First, the effects of basicity and contents of silicon, iron, CaF2, and carbon on the recovery rates of the three metals were analyzed using the slag amount prediction model, which was originally established from the A1203 balance of corundum crucible erosion behavior. Second, the effect of feeding mode, i.e., whether steel scrap and SSD briquettes were simultaneously added, on the recovery rates was discussed in detail. Third, the iron-bath reduction of SSD briquettes was thermodynamically analyzed. The results indicated that the recovery rates of the three metals are greater than 95% those of using a basicity of 1.5 and 6.0% CaF2, 15% carbon, and 7% ferrosilicon. The recovery rate of chromium increases twofold with the addition of ferrosilicon. The feeding mode of adding briquettes and steel scrap simultaneously is better for recovery of metals and separation of the metal and slag than the feeding mode of adding steel scrap firstly and then briquettes.展开更多
Flake BiOBr was first prepared by a solution method at room temperature. Then, the produced BiOBr was calcined at different temperatures. It was found that BiOBr is not a stable compound. It transforms to plate-like B...Flake BiOBr was first prepared by a solution method at room temperature. Then, the produced BiOBr was calcined at different temperatures. It was found that BiOBr is not a stable compound. It transforms to plate-like Bi24031Brll at around 750 ℃ and the formed Bi24O31Br11 can further convert to rod-like a-Bi203 at around 850℃. The prepared compounds were characterized with X-ray diffraction （XRD）, N2 physical adsorption, scanning electron microscopy （SEM）, and UV-Vis diffuse reflectance spectra （DRS）, respectively. The photocatalytic activity of the produced bismuth oxybromides was evaluated by photocatalytic decomposition of acid orange Ⅱ under both visible light （λ〉420 nm） and UV light （λ=365 nm） irradiation. Results show that these compounds have different band gaps and different photocatalytic properties. The band gap energies of the as-prepared samples were found to be 2.82, 2.79, 2.60 and 3.15 eV for BiOBr, BiOBr/Bi24O31Br, Bi24O31Br, and a-Bi2O3, respectively. Under both UV light and visible light irradiation, the photocatalytic activity follows the order： BiOBr/Bi24O31Br mixture 〉 BiOBr 〉 Bi24031Br〉a-Bi2O3. The change in photocatalytic activity could be attributed to the different light absorption ability and microstructures of the photocatalysts.展开更多
The adsorption behaviors of rare earth elements on clay minerals would have great influence on the mineralization process and the leaching process of the ion-adsorption type rare earths ore.In this work,the adsorption...The adsorption behaviors of rare earth elements on clay minerals would have great influence on the mineralization process and the leaching process of the ion-adsorption type rare earths ore.In this work,the adsorption thermodynamics of REEs on kaolin were investigated thoroughly and systematically.The experimental results showed that the adsorption characteristics of La,Nd,Y on kaolin did fit well with the Langmuir isotherm model and their saturated adsorption capacities were 1.731,1.587 and 0.971 mg/g,respectively.The free energy change（ΔG）values were –16.91 kJ/mol（La）,–16.05 kJ/mol（Nd）and –15.58 kJ/mol（Y）,respectively.The negative values of ΔG demonstrated that the adsorption of rare earth on kaolin was a spontaneously physisorption process.The deposit characteristic of the volcanic ion-adsorption type rare earths ore and the behavior of the rare earth in the column leaching process were also developed here.With the increase of the ore body depth,the distribution of the LREEs decreased and the HREEs increased.And the slight differences in the adsorption ability of REEs on clay minerals led to the fractionation effect in the column leaching process.These developed more evidences and better understanding of metallogenic regularity,and provided a theoretical basis and scientific approach to separation of the HREEs and LREEs in the leaching process.展开更多
基金financially supported by National National Key Research and Development Program of China (2019YFC1907801, 2018YFC1900305, 2018YFC1901601, 2018YFC1901602)the Natural Science Foundation of China (52004334, 51622406, 51634009 and U1704252)+4 种基金National 111 Project (No. B14034)the National Key R&D Program of China (2018YFC1901901)the Collab-orative Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources, Found of State Key Laboratory of Mineral Processing (BGRIMM-KJSKL-2017-13)the Fundamental Research Funds for the Central Universities of Central South University (2019zzts1712020zzts203)the Hunan Provincial Innovation Foundation for Postgraduate (CX20190227)。
文摘Despite the intriguing merits of lithium-sulfur(Li-S) systems, they still suffer from the notorious‘‘shuttling-effect" of polysulfides. Herein, carbon materials with rational tailoring of morphology and pores were designed for strong loading/adsorption with the controlling of energy-storage ability.Through rational tailoring, it is strongly verified that such engineering of evolutions result in variational of sulfur immobilization in the obtained carbon. As expected, the targeted sample delivers a stable capacity of 925 m Ah g^(-1) after 100 loops. Supporting by the "cutting-off" manners, it is disclosed that mesopores in carbon possess more fascinated traits than micro/macropores in improving the utilization of sulfur and restraining Li_(2)S_x(4≤x≤8). Moreover, the long-chain polysulfide could be further consolidated by auto-doping oxygen groups. Supported by in-depth kinetic analysis, it is confirmed that the kinetics of ion/e-transfer during charging and discharging could be accelerated by mesopores, especially in stages of the formation of solid S_(8) and Li_(2)S, further improving the capacity of ion-storage in Li-S battery. Given this, the elaborate study provide significant insights into the effect of pore structure on kinetic performance about Li-storage behaviors in Li-S battery, and give guidance for improving sulfur immobilization.
基金supported by the National Natural Science Foundation of China(Grants No.21067004 and No.21263005)the Technological Foundation of Jiangxi Province Education Office(No.GJJ12344)+1 种基金the Young Science and Technolgy Project of Jiangxi Province(No.20133BAB21003)the Young Scientist Training Project of Jiangxi Province(No.20122BCB23015)
文摘A series of novel Ni/CeOe-Al2O3 composite catalysts were synthesized by one-step citric acid complex method, The as-synthesized catalysts were characterized by N2 physical adsorption/desorption, X-ray diffraction （XRD）, Fourier transform infrared （FT-IR） spectroscopy, hydrogen temperature-programmed reduction （Hz-TPR）, X-ray photoelectron spectroscopy （XPS） and thermogravimetry analysis （TGA）. The effects of nickel content, calcination and reaction temperatures, gas hourly space velocity （GHSV） and inert gas dilution of N2 on their performance of catalytic partial oxidation of methane （CPOM） were investigated. Catalytic activity test results show that the highest methane conversion （〉85%）, the best selectivities to carbon monoxide （〉87%） and to hydrogen （〉95%）, the excellent stability and perfect Hz/CO ratio （2.0） can be obtained over Ni/CeO2-Al2O3 with 8 wt% Ni content calcined at 700 ℃ under the reaction condition of 750 ℃, CH4/O2 ratio of 2 ： 1 and gas hourly space velocity of 12000 mL.h-1 .g-1. Characterization results show that the good catalytic performance of this composite catalyst can be contributed to its large specific surface area （~108 m2.g-1）, small crystallite size, easy reducibility and low coking rate.
基金Funded by the National Natural Science Foundation of China(Nos.51174100,51564016 and 51564017)Natural Science Foundation of Jiangxi Province,China(No.20171ACB21042)
文摘The electronic structure, cohesive energy and interfacial energy of ferrite（100）/NbC（100） and TiC（100）/NbC（100） interfaces have been investigated by the first-principles calculation. Moreover, the heterogeneous nuclei mechanism of NbC particle was also analyzed. The results showed that the stacking sequences have a great influence on the cohesive energy and equilibrium interfacial separation of the abovementioned interfaces. Compared with C-terminated interfaces, the cohesive energy of Nb-terminated ones is lower while the equilibrium interface distance is larger. Among the two C-terminated interface structures, the interfacial energy between the NbC and ferrite is 4.54 J/m^2, which is larger than that of NbC/TiC interface（1.80 J/m^2）. Therefore, NbC particles prefer heterogeneous nucleation on TiC particles surface rather than the ferrite matrix, which agrees well with the experimental result.
基金supported by National Natural Science Foundation of China(No.21067004)Research Fund for the Doctoral Program of Jiangxi University of Science and Technology(22020)
文摘Objective It is imperative to provide some consistent experimental results for the extraction of flavonid from Fructus Gardeniae. Methods The key extraction parameters that influenced the yield of flavonid from Fructus Gardeniae were optimized by employing an orthogonal experiment [L9（3）4], including the ratio of buffer solution （Na2B4O7· 10H2O） to raw material, concentration of Fructus Gardeniae in extracting solution, extraction time and pH of buffer solution. An UV/Vis detector was used to perform the qualitative and quantitative analyses of the extracted flavonid with the using of the standard sample. Results The maximum extraction yield of the crude extract was 5.0533 （mg/g） after 20 min when the mass ratio of Na2B4O7 · 10H2O to raw material was 0.4%, the concentration of Fructus Gardeniae in the extraction solution was 1/12 （g/mL）, and pH of buffer solution was 4.5. The positive reactions to the Molish and HCI-Mg tests suggested that the extracted compound was flavonoid, and FTIR measurements also identified the presence of flavonoid in the extracts. Conclusion This work is expected to provide a basis for further research, development, and utilization of Fructus gardenia in flavonid extraction.
文摘Currently,air pollution is being exacerbated by rapid social,economic,and industrial development.Major air pollutants include volatile organic compounds(VOCs)and CO.Photocatalytic and thermocatalytic technology can be used to convert VOCs and CO into harmless gases effectively.Recently,photothermal synergistic catalysis has aroused much attention because of its higher performance than those of individual photocatalytic and thermocatalytic processes.There have been many reviews on separate photocatalysts and thermocatalysts for the treatment of VOCs and CO,but few reviews have focused on photothermal synergistic catalysis.In this minireview,we concentrate on recent progress into photothermal synergistic catalysis for the efficient removal of VOCs and CO.The treatment of typical VOCs(such as benzene,toluene,ethanol,formaldehyde,acetone,propylene,and propane)and CO are summarized and analyzed.Furthermore,we discuss the use of conventional reactor technology,such as fixed‐bed quartz reactors,for VOCs and CO removal.We also discuss the mechanism of the photothermal synergistic catalytic removal of VOCs and CO.Finally,we present perspectives for the photothermal synergistic catalytic removal of VOCs and CO.
基金supported by the National Natural Science Foundation of China(21707055,21567008,21607064)Program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technology,Program of 5511 Talents in Scientific and Technological Innovation of Jiangxi Province(20165BCB18014)+3 种基金Academic and Technical Leaders of the Main Disciplines in Jiangxi Province(20172BCB22018)Jiangxi Province Natural Science Foundation(20161BAB203090,20181BAB213010,20181BAB203018)Young Science Foundation of Jiangxi Province Education Office(GJJ160671)Open Project Program of the State Key Laboratory of Photocatalysis on Energy and Environment(SKLPEE-KF201712)in Fuzhou University基金来源:国家自然科学基金(21707055,21567008,21607064)~~
文摘Semiconductor photocatalysts are extensively applied in environmental treatment and energy conversion.However,one of their major disadvantages is their relatively low photocatalytic performance owing to the recombination of generated electron-hole pairs.The presence of the phase junction is an effective way to promote the photocatalytic activity by increasing the separation efficiency of the electron-hole pairs.Accordingly,extensive research has been conducted on the design of phase junctions of photocatalysts to improve their charge transfer properties and efficiencies.Therefore,for the design of an appropriate phase junction and the understanding of the mechanism of electron-hole separation,the development of the photocatalytic phase junction,including the preparation methods of the heterogeneous materials,is tremendously important and helpful.Herein,the commonly used,externally induced phase transformation fabrication techniques and the primary components of the semiconductors are reviewed.Future directions will still focus on the design and optimization of the phase junction of photocatalytic materials according to the phase transition with higher efficiencies for broadband responses and solar energy utilization.Additionally,the most popular phase transformation fabrication techniques of phase junctions are briefly reviewed from the application viewpoint.
基金supported by the National Natural Science Foundation of China(21567008,21607064,21707055)Program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technology+2 种基金Program of 5511 Talents in Scientific and Technological Innovation of Jiangxi Province(20165BCB18014)Academic and Technical Leaders of the Main Disciplines in Jiangxi Province(20172BCB22018)Jiangxi Province Natural Science Foundation(20161BAB203090)~~
文摘A series of N‐CQDs/Ag2CO3composite crystals(where N‐CQDs=Nitrogen doped carbon quantumdots)were prepared by adding different volumes of a solution of N‐CQDs during Ag2CO3crystalgrowth.Under irradiation from a350‐W Xe lamp light(with optical filter,λ≥420nm),the performanceof N‐CQDs/Ag2CO3in photocatalytic degradation of phenol was evaluated.The as‐preparedsamples were analyzed by XRD,SEM,TEM,BET,element mapping,UV‐vis DRS,FT‐IR,XPS,transientphotocurrent response and EIS testing.The results showed that after coupling with trace amountsof N‐CQDs,both the photocatalytic activity and stability of Ag2CO3were greatly boosted.The additionof N‐CQDs solution influenced the crystallization of Ag2CO3,resulting in a distinct decrease inAg2CO3crystal size and an obvious increase in surface area.Moreover,the charge transfer resistancewas greatly reduced,and the separation efficiency of photogenerated electrons and holes wasstrongly promoted.The presence of NCQDs on the surface of the catalysts facilitates the transfer ofphotogenerated electrons,slowing the photocorrosion rate of Ag2CO3,and then resulting in higherstability than bare Ag2CO3in degradation.The synergistic effect of the improvement of morphologyand charge transfer rate thus accounted for the superior photocatalytic performance ofN‐CQDs/Ag2CO3.
基金supported by Youth Fund of Nanyang Normal University(QN2017046)
文摘A dual functional coordination polymer, namely, {[Tb（mat）（1.5）H2O]·2.5H2O}n（1, H2mta = 2-methoxyterephthalic acid）, was synthesized under solvothermal condition and characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, X-ray powder diffraction analysis（PXRD）, and thermogravimetric analysis（TGA）. Complex 1 exhibits a 3D framework based on infinite rod-shaped secondary building units（SBUs）. Furthermore, the solid-state luminescent property and magnetic properties of the complex were investigated at room temperature; the results show that the complex exhibits excellent luminescent properties in green luminescence and weak antiferromagentic behavior.
基金supported by the National Natural Science Foundation of China(21567008,21607064,21707055,21763011)Program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technology+2 种基金Program of 5511 Talents in Scientific Technological Innovation of Jiangxi Province(20165BCB18014)Academic and Technical Leaders of the Main Disciplines in Jiangxi Province(20172BCB22018)Jiangxi Province Natural Science Foundation China(20161BAB203090,20161BAB213083,20171ACB21041)~~
文摘CaMg(CO3)2microspheres were prepared and used as hard templates to fabricate a series of CaMg(CO3)2@Ag2CO3composite microspheres via a fast and low‐cost ion exchange process.The effects of ion exchange time and temperature on the physicochemical properties and photocatalytic activities of the composite microspheres were studied through photocatalytic degradation of Acid Orange II under xenon lamp irradiation.The obtained samples were analyzed by X‐ray diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy,UV‐vis diffuse reflectance spectroscopy,N2physical adsorption,and photocurrent tests.The CaMg(CO3)2@Ag2CO3sample with the highest activity was obtained with an ion exchange time of4h and temperature of40°C.The degradation rate of Acid Orange II by this sample reached83.3%after15min of light irradiation,and the sample also performed well in phenol degradation.The CaMg(CO3)2@Ag2CO3produced under these ion exchange conditions showed a well‐ordered hierarchical morphology with small particle sizes,which was beneficial to light absorption and the transfer of photoelectrons(e-)and holes(h+)to the catalyst surface.Moreover,the separation of photogenerated carriers over the composites was greatly improved relative to bare CaMg(CO3)2.Despite the very low content of Ag2CO3(2.56%),excellent photocatalytic performance was obtained over the CaMg(CO3)2@Ag2CO3microspheres.
基金supported by the National Natural Science Foundation of China(21703046)the National Key R&D of China(2016YFF0203803,2016YFA0200902)~~
文摘Photocatalytic water splitting has increasingly attracted attention as one of the most useful methods of converting solar energy into chemical fuel.However,the undesirable reverse reaction significantly limits the enhancement of efficiency.Herein,we fabricated an Au nanorods/TiO2 nanodumbbells structure photocatalyst(Au NRs/TiO2 NDs)via a facile synthetic strategy,which has spatially separated oxidation and reduction reaction zones.Owing to the unique structure,the charge separation of these photocatalysts can be significantly improved and the reverse reaction can be efficiently inhibited.The photogenerated electrons were injected from the TiO2 to the Au NRs,and a positively charged TiO2 region and negatively charged Au region were formed under UV irradiation.An enhanced hydrogen production performance was obtained compared with that seen in normal Au-TiO2 heterostructure.Under optimized conditions,the H2-production rate can reach up to 60,264μmol/g/h,about six times higher than previously reported Au/TiO2 photocatalysts.Besides this,our work also demonstrates the key factors of precise synthesis of the Au NRs/TiO2 NDs structure,which provides a new perspective and experience for the design of similar catalysts.
基金funded by the National Science Foundation of China 40872002 and 41063001the Open Foundation of State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry(201004)+1 种基金the Youth Science Foundation of Jiangxi University of Science and Technology (JXXJBS12006)the China Geological Survey (No.1212010818085)
文摘This paper presents a description of the river terrace at Tangjia Village in Lhasa, Tibet. Selected types of phytolith and pollen were used as proxies to study the paleoclimate in the study area. Ancient climate and vegetation changes since 10 ka BP were examined. The results demonstrated that between 10.2 and 8.9 ka BP, the dominating phytolith was the cold type and the dominating vegetation type was grassland-forest. This indicated that the climate changed from cool-humid to cool-dry and later turned back into a cool-humid climate. Between 8.9 and 8.1 ka BP, the main types of phytoliths were tooth, dumbbell, and polyhedral. This suggests that the vegetation consisted of forest-grassland and the period＇s climate had become warmer. Between 8.1 and 6.7 ka BP, the warm index of phytolith assembelage gradually increased, whereas the spore and pollen assembelage revealed that the vegetation was forest with hardwood. This suggested that the paleoclimate was warmest in this period. The herbaceous vegetation increased gradually, indicating that the climate had become colder since 7.5 ka BP. Between 6.7 and 4.6 ka BP, cold type phytolith such as tooth and cap were found. Simultaneously, the pollen assembelage indicated that the vegetation shifted from grassland to forest and then turned back into grassland. This implies that the climate fluctuated from cold-dry to cool- humid. Between 4.6 and 1.9 ka BP, the dominate type of phytolith was cold type and its warm index was in the range 0.04-0.28, suggesting a herbaceous vegetation cover and indicating that the climate was cold. The phytolith warm index from 1.9 ka BP revealed that the climate was continuously decreasing, and most of the pollen assembelage consisted of Chenopodiaceae and Artemisia. This conclusion is in agreement with the phytolith result that indicates that the climate was becoming colder and colder.
基金financially supported by the National Natural Science Foundation of China(Nos.21805244,51776188)the financial support from National Natural Science Foundation of China(Nos.21922811,21878270,21961160742)+1 种基金the Zhejiang Provincial Natural Science Foundation of China(No.LR19B060002)the Startup Foundation for HundredTalent Program of Zhejiang University,Jiangxi Province"Double Thousand Plan"Project(No.205201000020)。
文摘Thanks to tunable physical and chemical properties,two-dimensional(2D)materials have received intensive interest,endowing their excellent electrocatalytic performances for applications in energy conversion.However,their catalytic activities are largely determined by poor adsorption energy and limited active edge sites.Herein,a one-step electrochemical exfoliation strategy was developed to fabricate 2D Ni-doped MoS_(2)nanosheets(Ni-EX-MoS_(2))with a lateral size of500 nm and thickness of3.5 nm.Profiting from high electrical conductivity and abundant exposing active sites,Ni-EX-MoS_(2)catalyst displayed an admirable performance for electrochemical hydrogen evolution reaction(HER)with a low overpotential of 145 m V at 10 m A/cm^(2)as well as a small Tafel slope of 89 m V/dec in alkaline media,which are superior to those of the most reported MoS_(2)-based electrocatalysts.The formed Ni species with tuning electronic structure played a crucial role as primary active center of Ni-EX-MoS_(2),as well as the forming stable 1T/2H phase MoS_(2)interface demonstrated a synergistic effect on electrocatalytic HER performance.Further,Ni-EX-MoS_(2)was employed as a cathode electrode for alkaline Zn-H_(2)O battery,which displayed a high power density of 3.3 m W/cm^(2)with excellent stability.This work will provide a simple and effective guideline for design of electrochemically exfoliated transition metal-doped MoS_(2)nanosheets to inspire their practical applications in energy catalytic and storage.
基金financially supported by the Natural Science Foundation of Jiangxi Province (Nos. 20161BAB216121,20161BAB206136 and GJJ150638)the National Natural Science Foundation of China (No. 91326203)
文摘Ni-W-GO composite coatings were successfully plated on 45# steel substrate by co-electrodeposition technique in a Ni-W electrolyte solution, with different contents of graphene oxide (GO) nanoparticles in suspen? sion. The structure, phase composition and surface morphology of as-plated composite coatings were characterized by Raman, X-ray diffraction (XRD), scanning electron microscopy (SEM) attached with energy disperse spectroscopy (EDS), respectively. The hardness and tribological behavior of the present coatings were also evaluated by Vickers Hardness tester and high-speed reciprocating friction and wear tester, and the wear mechanism was discussed as well. The results show that layer-structured GO nanoparticles significantly affect the microstructure and grain size of the Ni-W-GO composite coatings. Meanwhile, GO nanoparticles embedded in Ni- W-GO coatings can obviously improve the hardness and wear resistance in comparison with the corresp on ding Ni- W coatings. The highest microhardness and wear resistance of Ni-W-GO composite coatings are obtained with 0.15 g·L^-1 GO employing.
基金the National Nature Science Foundation of China (21177049,51103063)the Program of Science and Technology of Zhejiang Province (2011C22096, 2011C37033)the Program for Science and Technology of Jiaxing (2011AY1027, 2011AY1007) for financial supports
文摘Nanofiber membranes from the composite of cellulose acetate/polyvinylpyrrolidone were prepared using electrospinning technique. After treated with water and alcoholic KOH to remove partially polyvinylpyrrolidone and deacetylate the cellulose acetate, the membranes were further functionalized with thiol groups using thioglycolic acid. Related materials were characterized using infrared and thermogravimetric analysis. And the results showed that the membranes were success of functionalisation. Then the nanofiber membranes were used in the sorption-desorption process. The effects of pH, contacting time and adsorption capacity of nanofiber membranes were studied against Cu（II）, Cd（II） and Pb（II） ions. And the maximum adsorption capacities of Pb （II）, Cu （II）, and Cd （II） ions were estimated at 30.96, 19.63, 34.70 mg g-1. Our results suggested that the adsorption be- haviour of metal ions could be described using Langmuir model. Their adsorption kinetics was in agreement with the model of pseudo-second order, suggesting chemical adsorption as the rate-limiting step of the adsorption mechanism. The durability of the thiol-functionalized cellulose nanofiber membranes was also evaluated by repetitive adsorption-desorption.
基金supported by the National Natural Science Foundation ofChina (21067004)the Natural Science Foundation of Jiangxi Province,China (2010GZH0048)Jiangxi Province Educatien Department of Science and Technology Project (GJJ 12344)
文摘A series of Mo-doped ZnO photocatalysts with different Mo-dopant concentrations have been prepared by a grind- ing-calcination method. The structure of these photocatalysts was characterized by a variety of methods, including N2 physical adsorption, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared （FT-IR） spectroscopy, photoluminescence （PL） emission spectroscopy, and UV-vis diffuse reflectance spectroscopy （DRS）. It was found that Mo6＋ could enter into the crystal lattice of ZnO due to the radius of MO6＋ （0.065 nm） being smaller than that of Zn2＋ （0.083 nm）. XRD results indicated that Mo6＋ suppressed the growth of ZnO crystals. The FT-IR spectroscopy results showed that the ZnO with 2 wt.% Mo-doping has a higher level of surface hydroxyl groups than pure ZnO. PL spectroscopy indicated that ZnO with 2 wt.% Mo-doping also exhibited the largest reduction in the intensity of the emission peak at 390 nm caused by the recombi- nation of photogenerated hole-electron pairs. The activities of the Mo-doped ZnO photocatalysts were investigated in the pho- tocatalytic degradation of acid orange II under UV light （2 = 365 nm） irradiation. It was found that ZnO with 2 wt.% Mo-doping showed much higher photocatalytic activity and stability than pure ZnO. The high photocatalytic performance of the Mo-doped ZnO can be attributed to a great improvement in the surface properties of ZnO, higher crystallinity and lower recombination rate of photogenerated hole-electron （e-/h＋） pairs. Moreover, the undoped Mo species may exist in the form of MoO3 and form MoO3/ZnO heterojunctions which further favors the separation of e/h＋ pairs.
基金Project supported by‘Hundreds Talents Program’from Chinese Academy of SciencesNational Natural Science Foundation of China(21571179)+1 种基金Science and Technology Major Project of the Fujian Province,China(2015HZ0101)Xiamen Universities,Research Institutions Jointing Enterprise Projects(3502Z20152009)
文摘Extraction and separation of yttrium in chloride medium using tri-n-octylmethylammonium（2-sec-octylphenoxy） acetate（[N（1888）][SOPAA]） as an extractant were studied in this article. Tri-n-butyl phosphate（TBP） was used as a phase modifier to accelerate phase separation and improve the stability of organic phase. The addition of TBP contributed to shortening phase separation time, increasing extraction capacity of rare earth elements（REEs） and decreasing viscosity of organic phase. The slope analysis method and infrared spectroscopy were conducted to investigate the ion-association extraction mechanisms. Extraction and stripping performances of the different systems were also compared. The article showed that the extraction performance of mixed [N（1888）][SOPAA] and TBP is superior to that of [N（1888）][SOPAA] for heavy rare earth element（HREE）.
文摘The reduction of zinc and iron oxides from electric arc furnace dust （EAFD） by carbon was investigated at temperatures between 800 and 1300℃. The analytic technique employed includes chemical analysis, X-ray fluores- cence spectroscopy （XRF）, X-ray powder diffraction （XRD）, scanning electron microscopy （SEM） equipped with X-ray energy dispersive spectrometry （EDS）, and thermodynamic database FactSage 6.2. It was found that the reduction of zinc and iron oxides depends largely on Boudouad reaction. At 900℃, zinc exists in tested samples as ZnO, which is reduced in the temperature range of 1000--1 100℃. At 1 100℃, 99.11% of the zinc is evaporated. The metallization ratio of Fe is 79.19% at 1300℃, as the content of Fe2＋ is still 9.40%. A higher temperature is thus required for a higher reduction degree of Fe oxides by solid or gaseous carbon.
基金This research was supported by the National Natural Science Foundation of China （Grant No. 51304053）, Jiangxi University of Science and Technology Doctoral Start-up Fund （No. 3401223181）.
文摘The leaching of chromium from stainless steel dust （SSD） is deleterious to the environment. To address this issue, the reduction of SSD briquettes can be employed to effectively extract chromium. The recovery rates of iron, chromium, and nickel via ironbath reduction of SSD briquettes were determined using X-ray fluorescence spectroscopy, X-ray diffraction, and scanning electron microscopy measurements. First, the effects of basicity and contents of silicon, iron, CaF2, and carbon on the recovery rates of the three metals were analyzed using the slag amount prediction model, which was originally established from the A1203 balance of corundum crucible erosion behavior. Second, the effect of feeding mode, i.e., whether steel scrap and SSD briquettes were simultaneously added, on the recovery rates was discussed in detail. Third, the iron-bath reduction of SSD briquettes was thermodynamically analyzed. The results indicated that the recovery rates of the three metals are greater than 95% those of using a basicity of 1.5 and 6.0% CaF2, 15% carbon, and 7% ferrosilicon. The recovery rate of chromium increases twofold with the addition of ferrosilicon. The feeding mode of adding briquettes and steel scrap simultaneously is better for recovery of metals and separation of the metal and slag than the feeding mode of adding steel scrap firstly and then briquettes.
文摘Flake BiOBr was first prepared by a solution method at room temperature. Then, the produced BiOBr was calcined at different temperatures. It was found that BiOBr is not a stable compound. It transforms to plate-like Bi24031Brll at around 750 ℃ and the formed Bi24O31Br11 can further convert to rod-like a-Bi203 at around 850℃. The prepared compounds were characterized with X-ray diffraction （XRD）, N2 physical adsorption, scanning electron microscopy （SEM）, and UV-Vis diffuse reflectance spectra （DRS）, respectively. The photocatalytic activity of the produced bismuth oxybromides was evaluated by photocatalytic decomposition of acid orange Ⅱ under both visible light （λ〉420 nm） and UV light （λ=365 nm） irradiation. Results show that these compounds have different band gaps and different photocatalytic properties. The band gap energies of the as-prepared samples were found to be 2.82, 2.79, 2.60 and 3.15 eV for BiOBr, BiOBr/Bi24O31Br, Bi24O31Br, and a-Bi2O3, respectively. Under both UV light and visible light irradiation, the photocatalytic activity follows the order： BiOBr/Bi24O31Br mixture 〉 BiOBr 〉 Bi24031Br〉a-Bi2O3. The change in photocatalytic activity could be attributed to the different light absorption ability and microstructures of the photocatalysts.
基金Project supported by National Science and Technology Support Program of China(2015BAB16B01)Training Program of Major Academic and Technical Leaders in Jiangxi Province(20142BCB22005)Top Youth Talent Training Program of"Gan Po 555 Talents Project"of Jiangxi Province
文摘The adsorption behaviors of rare earth elements on clay minerals would have great influence on the mineralization process and the leaching process of the ion-adsorption type rare earths ore.In this work,the adsorption thermodynamics of REEs on kaolin were investigated thoroughly and systematically.The experimental results showed that the adsorption characteristics of La,Nd,Y on kaolin did fit well with the Langmuir isotherm model and their saturated adsorption capacities were 1.731,1.587 and 0.971 mg/g,respectively.The free energy change（ΔG）values were –16.91 kJ/mol（La）,–16.05 kJ/mol（Nd）and –15.58 kJ/mol（Y）,respectively.The negative values of ΔG demonstrated that the adsorption of rare earth on kaolin was a spontaneously physisorption process.The deposit characteristic of the volcanic ion-adsorption type rare earths ore and the behavior of the rare earth in the column leaching process were also developed here.With the increase of the ore body depth,the distribution of the LREEs decreased and the HREEs increased.And the slight differences in the adsorption ability of REEs on clay minerals led to the fractionation effect in the column leaching process.These developed more evidences and better understanding of metallogenic regularity,and provided a theoretical basis and scientific approach to separation of the HREEs and LREEs in the leaching process.
