The mutual separation characteristics were investigated for the neighboring Sm, Eu and Gd from their ternary oxide mixture Sm 2O 3 Eu 2O 3 Gd 2O 3 by a stepwise chlorination chemical vapor transport reaction ...The mutual separation characteristics were investigated for the neighboring Sm, Eu and Gd from their ternary oxide mixture Sm 2O 3 Eu 2O 3 Gd 2O 3 by a stepwise chlorination chemical vapor transport reaction within 6 h using AlCl 3 as complex former. The rare earth chlorides were more readily transported and concentrated in the middle temperature range of 980～1100 K and the transport efficiency was in the order of Sm≈Gd>Eu. The separation factor, expressed as molar ratio for the resulting chlorides, was 1 70 for Eu∶Sm, 1 88 for Eu∶Gd, 1 24 for Sm∶Gd in the higher temperature region, and 2 76 for Sm∶Eu, 2 83 for Gd∶Eu and 1 12 for Gd∶Sm in the lower temperature region, respectively. All results are much higher than those of the conventional wet process.展开更多
Heterostructured photocatalysts provide an effective way to achieve enhanced photocatalytic performances through efficient charge separation.Although both wide-and narrow-band-gap photocatalysts have been widely inves...Heterostructured photocatalysts provide an effective way to achieve enhanced photocatalytic performances through efficient charge separation.Although both wide-and narrow-band-gap photocatalysts have been widely investigated,the charge separation and transfer mechanism at the contacting interface of the two has not been fully revealed.Here,a novel SrTiO3/BiOI(STB)heterostructured photocatalyst was successfully fabricated by using a facile method.The heterostructure in the photocatalyst extends the photoabsorption to the visible light range,and thus,high photocatalytic NO removal performance can be achieved under visible light irradiation.A combination of experimental and theoretical evidences indicated that the photogenerated electrons from the BiOI semiconductor can directly transfer to the SrTiO3 surface through a preformed electron delivery channel.Enhanced electron transfer was expected between the SrTiO3 and BiOI surfaces under light irradiation,and leads to efficient ROS generation and thus a high NO conversion rate.Moreover,in situ diffused reflectance infrared Fourier transform spectroscopy revealed that STB can better inhibit the accumulation of the toxic intermediate NO2 and catalyze the NO oxidation more effectively.This work presents a new insight into the mechanism of the interfacial charge separation in heterostructures and provides a simple strategy to promote the photocatalytic technology for efficient and safe air purification.展开更多
A number of epuilibrium data of single stage in the system (Nd-SM)Cl_3-HCl-H_2O-1mol/L HEHEHP-kerosence was determined On the basis of epuilibrium data, two mathematical describing extract epui-librium of Nd and Sm...A number of epuilibrium data of single stage in the system (Nd-SM)Cl_3-HCl-H_2O-1mol/L HEHEHP-kerosence was determined On the basis of epuilibrium data, two mathematical describing extract epui-librium of Nd and Sm were developed.The models cover wide available ranges (the total RE concentration inepuilibrated apueous phase is 0. 07～0. 77 mol/L and the acidity is 0. 11～0. 48 mol/L; the mole fraction ofMd or Sm is 0. 020～0. 998) with small average relative errors(The model of Nd is 6. 11 % and the model ofSm is 3. 07 %, respectively ) With the developed models, the extract behaviors of Nd and sM, such as thedistribution of rare earth concentrations in both phase, the effects of acidity, RE concentration, mole fractionof RE in aqueous phase on the RE concentration in organic phase, were researched The separation circuits be-tween Nd and Sm simulated and performed by the experiments in laboratory. The purities obtained prod-uct of Nd_2O_3O_3 as well as Sm_2O_3 were higher than 99%.Two calculation programs were written in BASIC language. One of them is used for publishing epuilibri-um model and another is used for simulation of fractional solvent extraction. The amulation results obtainedmay serve as a reference for designing solvent extraction process.展开更多
2,3-disulfanylbutanedioic acid（DMSA） was found to be a selective depressant in the flotation separation of coppermolybdenum sulfides.The flotation results suggest that a low dosage of DMSA has a strong depression ef...2,3-disulfanylbutanedioic acid（DMSA） was found to be a selective depressant in the flotation separation of coppermolybdenum sulfides.The flotation results suggest that a low dosage of DMSA has a strong depression effect on chalcopyrite in the p H range between 4 and 12.At p H 6,the recoveries of molybdenum are up to 85%,75%,and 80% while those of chalcopyrite are 15%,5%,and 20% respectively when flotation tests are carried out with single minerals,mixed minerals and molybdenum-bearing copper concentrates.Adsorption isotherms measurement indicates that DMSA adsorbs more strongly on chalcopyrite than on molybdenite.The frontier orbital calculation reveals that the two S atoms of DMSA molecule are active centers for the adsorption of the DMSA molecule on chalcopyrite surface.Fermi level calculation shows that chalcopyrite can obtain electrons from the DMSA molecule while molybdenite cannot.展开更多
Photocatalysis. which utilizes solar energy to trigger chemical reactions, is one of the most desirable solar-energy-conversion approaches. Graphitic carbon nitride （g-C3N4）. as an attractive metal-free photocatalys...Photocatalysis. which utilizes solar energy to trigger chemical reactions, is one of the most desirable solar-energy-conversion approaches. Graphitic carbon nitride （g-C3N4）. as an attractive metal-free photocatalyst, has drawn worldwide research interest in the area of solar energy conversion due to its easy synthesis, earth-abundant nature, physicochemical stability and visible-light-responsive properties. Over the past ten years, g-C3N4 based photocatalysts have experienced intensive exploration, and great progress has been achieved. However, the solar conversion efficiency is still far from industrial applications due to the wide bandgap, severe charge recombination, and lack of surface active sites. Many strategies have been proposed to enhance the light absorption, reduce the recombination of charge carriers and accelerate the surface kinetics. This work makes a crucial review about the main contributions of various strategies to the light harvesting, charge separation and surface kinetics of g-C3N4 photocatalyst. Furthermore, the evaluation measurements for the enhanced light harvesting, reduced charge recombination and accelerated surface kinetics will be discussed. In addition, this review proposes future trends to enhance the photocatalytic performance of g-C3N4 photocatalyst for the solar energy conversion.展开更多
A silylated melamine sponge(SMS)was prepared by two simple steps,namely,immersion and dehydration of a melamine sponge coated with methyltrichlorosilane.The silylated structure of SMS was characterized by FT-IR(Fourie...A silylated melamine sponge(SMS)was prepared by two simple steps,namely,immersion and dehydration of a melamine sponge coated with methyltrichlorosilane.The silylated structure of SMS was characterized by FT-IR(Fourier-transform infrared)spectroscopy,SEM(Scanning electron microscopy)and in terms of water contact angles.Its oil-water absorption and separation capacities were measured by FT-IR and UV-visible spectrophoto-metry.The experimental results have shown that oligomeric silanol covalently bonds by Si-N onto the surface of melamine sponge skeletons.SMS has shown superhydrophobicity with a water contact angle exceeding 150°±1°,a better separation efficiency with regard to diesel oil(by 99.31%(wt/wt%)in oil-water mixture and even up to 99.99%(wt/wt%)for diesel oil in its saturated aqueous solution.Moreover,SMS inherited the intrinsicflame retardancy of the melamine sponge.In general,SMS has shown superhydrophobicity,high porosity,excellent selectivity,remarkable recyclability,and better absorption capacity for various oils and organic solvents,and a high separation efficiency for oil in saturated aqueous solutions.展开更多
To further improve the charge separation and photocatalytic activities of g-C3N4 and CdMoO4 under visible light irradiation,CdMoO4/g-C3N4 composites were rationally synthesized by a facile precipitation-calcination pr...To further improve the charge separation and photocatalytic activities of g-C3N4 and CdMoO4 under visible light irradiation,CdMoO4/g-C3N4 composites were rationally synthesized by a facile precipitation-calcination procedure.The crystal phases,morphologies,chemical compositions,textural structures,and optical properties of the as-prepared composites were characterized by the corresponding analytical techniques.The photocatalytic activities toward degradation of rhodamine B solution were evaluated under visible light irradiation.The results revealed that integrating CdMoO4 with g-C3N4 could remarkably improve the charge separation and photocatalytic activity,compared with those of pristine g-C3N4 and CdMoO4.This would be because the CdMoO4/g-C3N4 composites could facilitate the transfer and separation of the photoexcited electron-hole pairs,which was confirmed by electrochemical impedance spectroscopy,transient photocurrent responses,and photoluminescence measurements.Moreover,active species trapping experiments demonstrated that holes(h+)and superoxide radicals(?O2?)were the main active species during the photocatalytic reaction.A possible photocatalytic mechanism was proposed on the basis of the energy band structures determined by Mott-Schottky tests.This work would provide further insights into the rational fabrication of composites for organic contaminant removal.展开更多
The separation of Eu^3 ＋is studied with a dispersion combined liquid membrane（DCLM）,in which polyvinylidene fluoride membrane（PVDF）is used as the liquid membrane support,dispersion solution containing HCl solutio...The separation of Eu^3 ＋is studied with a dispersion combined liquid membrane（DCLM）,in which polyvinylidene fluoride membrane（PVDF）is used as the liquid membrane support,dispersion solution containing HCl solution as the stripping solution,and 2-ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester（P507）dissolved in kerosene as the membrane solution.The effects of pH value,initial concentration of Eu3 ＋and different ionic strength in the feed phase,volume ratio of membrane solution to stripping solution,concentration of HCl solution, concentration of carrier,different stripping agents in the dispersion phase on the separation are investigated.The optimum condition for separation of Eu3 ＋is that concentration of HCl solution is 4.0 mol·L 1,concentration of carrier is 0.16 mol·L 1,and volume ratio of membrane solution to stripping solution is 30︰30 in the dispersion phase, and pH value is 4.2 in the feed phase.The ionic strength has no significant effect on separation of Eu3 ＋.Under the optimum condition,when the initial concentration of Eu3 ＋is 0.8×10 4mol·L 1,the separation percentage of Eu 3＋is 95.3%during the separation time of 130 min.The kinetic equation is developed in terms of the law of mass diffusion and the theory of interface chemistry.The diffusion coefficient of Eu3 ＋in the membrane and the thickness of diffusion layer between feed phase and membrane phase are obtained and their values are 1.48×10 7m 2·s 1and 36.6μm,respectively.The results obtained are in good agreement with literature data.展开更多
文摘The mutual separation characteristics were investigated for the neighboring Sm, Eu and Gd from their ternary oxide mixture Sm 2O 3 Eu 2O 3 Gd 2O 3 by a stepwise chlorination chemical vapor transport reaction within 6 h using AlCl 3 as complex former. The rare earth chlorides were more readily transported and concentrated in the middle temperature range of 980～1100 K and the transport efficiency was in the order of Sm≈Gd>Eu. The separation factor, expressed as molar ratio for the resulting chlorides, was 1 70 for Eu∶Sm, 1 88 for Eu∶Gd, 1 24 for Sm∶Gd in the higher temperature region, and 2 76 for Sm∶Eu, 2 83 for Gd∶Eu and 1 12 for Gd∶Sm in the lower temperature region, respectively. All results are much higher than those of the conventional wet process.
基金supported by the National Natural Science Foundation of China(21822601,21501016,21777011)the National R&D Program of China(2016YFC02047)+1 种基金the Innovative Research Team of Chongqing(CXTDG201602014)the Natural Science Foundation of Chongqing(cstc2017jcyj BX0052)~~
文摘Heterostructured photocatalysts provide an effective way to achieve enhanced photocatalytic performances through efficient charge separation.Although both wide-and narrow-band-gap photocatalysts have been widely investigated,the charge separation and transfer mechanism at the contacting interface of the two has not been fully revealed.Here,a novel SrTiO3/BiOI(STB)heterostructured photocatalyst was successfully fabricated by using a facile method.The heterostructure in the photocatalyst extends the photoabsorption to the visible light range,and thus,high photocatalytic NO removal performance can be achieved under visible light irradiation.A combination of experimental and theoretical evidences indicated that the photogenerated electrons from the BiOI semiconductor can directly transfer to the SrTiO3 surface through a preformed electron delivery channel.Enhanced electron transfer was expected between the SrTiO3 and BiOI surfaces under light irradiation,and leads to efficient ROS generation and thus a high NO conversion rate.Moreover,in situ diffused reflectance infrared Fourier transform spectroscopy revealed that STB can better inhibit the accumulation of the toxic intermediate NO2 and catalyze the NO oxidation more effectively.This work presents a new insight into the mechanism of the interfacial charge separation in heterostructures and provides a simple strategy to promote the photocatalytic technology for efficient and safe air purification.
文摘A number of epuilibrium data of single stage in the system (Nd-SM)Cl_3-HCl-H_2O-1mol/L HEHEHP-kerosence was determined On the basis of epuilibrium data, two mathematical describing extract epui-librium of Nd and Sm were developed.The models cover wide available ranges (the total RE concentration inepuilibrated apueous phase is 0. 07～0. 77 mol/L and the acidity is 0. 11～0. 48 mol/L; the mole fraction ofMd or Sm is 0. 020～0. 998) with small average relative errors(The model of Nd is 6. 11 % and the model ofSm is 3. 07 %, respectively ) With the developed models, the extract behaviors of Nd and sM, such as thedistribution of rare earth concentrations in both phase, the effects of acidity, RE concentration, mole fractionof RE in aqueous phase on the RE concentration in organic phase, were researched The separation circuits be-tween Nd and Sm simulated and performed by the experiments in laboratory. The purities obtained prod-uct of Nd_2O_3O_3 as well as Sm_2O_3 were higher than 99%.Two calculation programs were written in BASIC language. One of them is used for publishing epuilibri-um model and another is used for simulation of fractional solvent extraction. The amulation results obtainedmay serve as a reference for designing solvent extraction process.
基金Project(2012BAB01B03)supported by the National Key Technology Support Program of China
文摘2,3-disulfanylbutanedioic acid（DMSA） was found to be a selective depressant in the flotation separation of coppermolybdenum sulfides.The flotation results suggest that a low dosage of DMSA has a strong depression effect on chalcopyrite in the p H range between 4 and 12.At p H 6,the recoveries of molybdenum are up to 85%,75%,and 80% while those of chalcopyrite are 15%,5%,and 20% respectively when flotation tests are carried out with single minerals,mixed minerals and molybdenum-bearing copper concentrates.Adsorption isotherms measurement indicates that DMSA adsorbs more strongly on chalcopyrite than on molybdenite.The frontier orbital calculation reveals that the two S atoms of DMSA molecule are active centers for the adsorption of the DMSA molecule on chalcopyrite surface.Fermi level calculation shows that chalcopyrite can obtain electrons from the DMSA molecule while molybdenite cannot.
基金the Australian Research Council for the financial support through its DP and FF programsthe Australian Government for the financial support through the Australian Government Research Training Program ScholarshipThe financial support from National Science Foundation of China(No.513228201)
文摘Photocatalysis. which utilizes solar energy to trigger chemical reactions, is one of the most desirable solar-energy-conversion approaches. Graphitic carbon nitride （g-C3N4）. as an attractive metal-free photocatalyst, has drawn worldwide research interest in the area of solar energy conversion due to its easy synthesis, earth-abundant nature, physicochemical stability and visible-light-responsive properties. Over the past ten years, g-C3N4 based photocatalysts have experienced intensive exploration, and great progress has been achieved. However, the solar conversion efficiency is still far from industrial applications due to the wide bandgap, severe charge recombination, and lack of surface active sites. Many strategies have been proposed to enhance the light absorption, reduce the recombination of charge carriers and accelerate the surface kinetics. This work makes a crucial review about the main contributions of various strategies to the light harvesting, charge separation and surface kinetics of g-C3N4 photocatalyst. Furthermore, the evaluation measurements for the enhanced light harvesting, reduced charge recombination and accelerated surface kinetics will be discussed. In addition, this review proposes future trends to enhance the photocatalytic performance of g-C3N4 photocatalyst for the solar energy conversion.
基金funded by Qingyang Science and Technology Support Project(KT2019-03)。
文摘A silylated melamine sponge(SMS)was prepared by two simple steps,namely,immersion and dehydration of a melamine sponge coated with methyltrichlorosilane.The silylated structure of SMS was characterized by FT-IR(Fourier-transform infrared)spectroscopy,SEM(Scanning electron microscopy)and in terms of water contact angles.Its oil-water absorption and separation capacities were measured by FT-IR and UV-visible spectrophoto-metry.The experimental results have shown that oligomeric silanol covalently bonds by Si-N onto the surface of melamine sponge skeletons.SMS has shown superhydrophobicity with a water contact angle exceeding 150°±1°,a better separation efficiency with regard to diesel oil(by 99.31%(wt/wt%)in oil-water mixture and even up to 99.99%(wt/wt%)for diesel oil in its saturated aqueous solution.Moreover,SMS inherited the intrinsicflame retardancy of the melamine sponge.In general,SMS has shown superhydrophobicity,high porosity,excellent selectivity,remarkable recyclability,and better absorption capacity for various oils and organic solvents,and a high separation efficiency for oil in saturated aqueous solutions.
基金supported by the Open Project Program of Hubei Key Laboratory of Animal Nutrition and Feed Science,Wuhan Polytechnic University(No.201808)Hubei Important Project of Technological Innovation(2018ABA094)~~
文摘To further improve the charge separation and photocatalytic activities of g-C3N4 and CdMoO4 under visible light irradiation,CdMoO4/g-C3N4 composites were rationally synthesized by a facile precipitation-calcination procedure.The crystal phases,morphologies,chemical compositions,textural structures,and optical properties of the as-prepared composites were characterized by the corresponding analytical techniques.The photocatalytic activities toward degradation of rhodamine B solution were evaluated under visible light irradiation.The results revealed that integrating CdMoO4 with g-C3N4 could remarkably improve the charge separation and photocatalytic activity,compared with those of pristine g-C3N4 and CdMoO4.This would be because the CdMoO4/g-C3N4 composites could facilitate the transfer and separation of the photoexcited electron-hole pairs,which was confirmed by electrochemical impedance spectroscopy,transient photocurrent responses,and photoluminescence measurements.Moreover,active species trapping experiments demonstrated that holes(h+)and superoxide radicals(?O2?)were the main active species during the photocatalytic reaction.A possible photocatalytic mechanism was proposed on the basis of the energy band structures determined by Mott-Schottky tests.This work would provide further insights into the rational fabrication of composites for organic contaminant removal.
基金Supported by the National Natural Science Foundation of China（90401009） the Foundation for Planning Project of West Action of Chinese Academy of Sciences（KZCX2-XB2-13） the Research Fund for Excellent Doctoral Thesis of Xi’an University of Technology（602-210805）
文摘The separation of Eu^3 ＋is studied with a dispersion combined liquid membrane（DCLM）,in which polyvinylidene fluoride membrane（PVDF）is used as the liquid membrane support,dispersion solution containing HCl solution as the stripping solution,and 2-ethyl hexyl phosphonic acid-mono-2-ethyl hexyl ester（P507）dissolved in kerosene as the membrane solution.The effects of pH value,initial concentration of Eu3 ＋and different ionic strength in the feed phase,volume ratio of membrane solution to stripping solution,concentration of HCl solution, concentration of carrier,different stripping agents in the dispersion phase on the separation are investigated.The optimum condition for separation of Eu3 ＋is that concentration of HCl solution is 4.0 mol·L 1,concentration of carrier is 0.16 mol·L 1,and volume ratio of membrane solution to stripping solution is 30︰30 in the dispersion phase, and pH value is 4.2 in the feed phase.The ionic strength has no significant effect on separation of Eu3 ＋.Under the optimum condition,when the initial concentration of Eu3 ＋is 0.8×10 4mol·L 1,the separation percentage of Eu 3＋is 95.3%during the separation time of 130 min.The kinetic equation is developed in terms of the law of mass diffusion and the theory of interface chemistry.The diffusion coefficient of Eu3 ＋in the membrane and the thickness of diffusion layer between feed phase and membrane phase are obtained and their values are 1.48×10 7m 2·s 1and 36.6μm,respectively.The results obtained are in good agreement with literature data.
