The equilibrium and kinetics of methyl isobutyl ketone(MIBK) extraction resin for adsorption and separation of zirconium and hafnium were studied under the different conditions of acidity,initial total concentrations ...The equilibrium and kinetics of methyl isobutyl ketone(MIBK) extraction resin for adsorption and separation of zirconium and hafnium were studied under the different conditions of acidity,initial total concentrations of zirconium and hafnium and temperature.The equilibrium data of both zirconium and hafnium are found to follow the Freundlich adsorption isotherm,and the Freundlich isotherm constants(KF) are 3.53 and 0.64 mg/g,respectively.The equilibrium data of zirconium also fit the Langmuir adsorption isotherm,and the saturation adsorption capacity(Qmax) and the Langmuir isotherm constant(KL)are 75.93 mg/g and-0.012 7 L/g,respectively.The obtained kinetic data of both zirconium and hafnium are found to fit the HO pseudo-second-order kinetic model,and the rate constants of pseudo-second-order equation(k2) are-0.019 and 0.41 g/(mg·min),respectively.Column tests show that the MIBK extraction resin could be used as efficient adsorbent material for separating hafnium from zirconium.展开更多
The electrochemical reduction of Zr^4＋（complex） ions in NaCl-KCl-K2ZrF6 molten salt on Pt electrode was investigated using cyclic voltammetry and square wave voltammetry at 1023 K.Two cathodic reduction peaks relat...The electrochemical reduction of Zr^4＋（complex） ions in NaCl-KCl-K2ZrF6 molten salt on Pt electrode was investigated using cyclic voltammetry and square wave voltammetry at 1023 K.Two cathodic reduction peaks related to Zr^4＋/Zr^2＋ and Zr^2＋/Zr steps were observed in the cyclic voltammograms.The result was also confirmed by square wave voltammetry.The diffusion coefficient of Zr^4＋（complex） ions at 1023 K in NaCl-KCl-K2ZrF6 melt,measured by cyclic voltammetry,is about 4.22×10^-6 cm^2/s.The characterization of the deposits obtained by potentiostatic electrolysis at different potentials was investigated by XRD,and the results were well consistent with the electrochemical reduction mechanism of Zr^4＋（complex） ions.展开更多
A hydrogen permeation barrier was manufactured by the in situ reaction of zirconium hydride with oxygen. A reduction in the hydrogen permeation of the oxide films was detected by measuring the mass difference of the z...A hydrogen permeation barrier was manufactured by the in situ reaction of zirconium hydride with oxygen. A reduction in the hydrogen permeation of the oxide films was detected by measuring the mass difference of the zirconium hydride samples after the dehydrogenation experiment. The reaction of zirconium hydride with oxygen occurs only under the condition that the temperature is higher than 673 K in the oxygen partial pressure of 0.1 MPa. The oxide film is composed of two layers, a permeable oxide layer and a dense oxide layer, and the main phase of the oxide film is ZrO2 with baddeleyite structure. The XPS analysis shows that O-H bonds exist in the oxide film, which are helpful for resisting hydrogen diffusion through the oxide film.展开更多
The recovery of nickel from laterite ore with sulphuric acid under the effect of microwave irradiation was studied.The experimental results indicated that the extraction rate of nickel was influenced by reaction time,...The recovery of nickel from laterite ore with sulphuric acid under the effect of microwave irradiation was studied.The experimental results indicated that the extraction rate of nickel was influenced by reaction time,sulphuric acid concentration,and temperature,especially by microwave power.The results obtained from the experiments of orthogonal arrays showed that the optimum conditions of sulphuric acid concentration,reaction time,microwave power,and temperature were 25 vol.%,1.5 h,600 W,and 90°C,respectively.Under the optimal conditions,the nickel recovery could reach approximately 90.8%,which was higher than that obtained by conventional water bath heating.Kinetic experiments showed that the leaching of nickel in a sulphuric acid medium was controlled by chemical reaction occurring on the surface of laterite ore.The apparent activation energy was 38.9 kJ/mol.Microwave heating technology is efficient,clean,and easy to control and facilitate continuous processing of materials.展开更多
The decomposition process for zircon sand concentrate using mixed base of sodium hydroxide partly replaced by calcium oxide was inrestigated.It is found that the decomposition rate of zircon gradually increased with t...The decomposition process for zircon sand concentrate using mixed base of sodium hydroxide partly replaced by calcium oxide was inrestigated.It is found that the decomposition rate of zircon gradually increased with the increase of the reaction temperature and time.The decomposition rate is over 97% with the conditions that CaO/zircon molar ratio is 0.25 ～ 0.75 at 800 ℃ for 1 h.Whereas the decomposition rate decreased when the molar ratio was more than 0.75.Also,thermogravimetry-differential thermal analysis(TG-DTA) and X-ray diffraction(XRD) were used to study the reaction mechanism of zircon decomposition process with CaO-NaOH.The results showed that Na_2O,which was generated by the reaction of CaO and Na_4SiO_4,increased the decomposition rate of zircon owing to its spread to the surface of zircon and played a role in decomposition process.展开更多
ZrO_(2)ceramic coatings were directly prepared on the surface of ZrH_(1.8) in silicate and phosphate elec-trolytes by micro-arc oxidation(MAO)technique,respec-tively.The microstructure,chemical composition and phase c...ZrO_(2)ceramic coatings were directly prepared on the surface of ZrH_(1.8) in silicate and phosphate elec-trolytes by micro-arc oxidation(MAO)technique,respec-tively.The microstructure,chemical composition and phase composition of ZrO_(2)ceramic coatings were inves-tigated by X-ray diffraction(XRD),energy-dispersive spectrometry(EDS)and scanning electron microscopy(SEM).The anti-permeation effect was measured by means of vacuum dehydrogenation experiment.It is found that the coating fabricated in phosphate electrolyte is more compact than that in silicate electrolyte.The coatings fabricated on the surface of ZrH_(1.8) are composed of M-ZrO_(2),T-ZrO_(2) and C-ZrO_(2).EDS analysis indicates that the coatings are mainly composed of O and Zr.Vacuum dehydrogenation experiment shows that the permeation reduction factor(PRF)of coating prepared in phosphate electrolyte is su-perior to that in the silicate electrolyte,and the PRF value reaches up to 11.2,which can enhance the resistance effect of hydrogen significantly.展开更多
Modified lithium manganese oxides were prepared by solid-state reaction of LiMn_(2)O_(4)and LiCoO_(2)as raw materials.A study was carried out by TG-DSC,XRD,DSC and electrochemical to analyse the reaction process and s...Modified lithium manganese oxides were prepared by solid-state reaction of LiMn_(2)O_(4)and LiCoO_(2)as raw materials.A study was carried out by TG-DSC,XRD,DSC and electrochemical to analyse the reaction process and structural characterization of products.The results show that the LiMn_(2)O_(4)reacts chemically with LiCoO_(2)at high temperature.All of Li and partial Co atoms can insert into the LiMn_(2)O_(4)crystal lattice and a newly formed spinel phase-modified LiMn_(2)O_(4)was obtained.The distribution of Co content is even in modified LiMn_(2)O_(4)compound.The modified LiMn_(2)O_(4)compound exhibits improved cycling stability at room and elevated temperature in comparison with the pure LiMn_(2)O_(4).展开更多
The present work aims to present the micro-arc oxidation(MAO)zirconia coating with superior compact-ness and moderate thickness on zirconium hydride.The experiments were designed according to L16(44)orthog-onal array ...The present work aims to present the micro-arc oxidation(MAO)zirconia coating with superior compact-ness and moderate thickness on zirconium hydride.The experiments were designed according to L16(44)orthog-onal array to optimize electrical parameters(frequency,negative voltage,positive voltage and MAO time),with four levels of each factor.The optimized value was pre-dicted and verified by the confirmation experiment.The anti-permeation effect was tested by means of vacuum dehydrogenation experiment.The optimized coating parameters are listed as follows:treating time of 25 min,frequency of 200 Hz,negative voltage of 150 V and pos-itive voltage of 380 V.Experimental results show that the optimized coating exhibits the highest compactness of 0.3705 mg·μm^(-1).This dense coating significantly enhan-ces the hydrogen anti-permeation effects,and the PRF value is improved by nearly 13 times in contrast with that of uncoated ZrH_(1.8).展开更多
Hydrogen desorption behaviors of zirconium hydride at temperature range of 100-900 ℃ in mixture gases of helium and oxygen was studied by gas phase analysis(GPA). Meanwhile,the morphologies of the oxide scale formed ...Hydrogen desorption behaviors of zirconium hydride at temperature range of 100-900 ℃ in mixture gases of helium and oxygen was studied by gas phase analysis(GPA). Meanwhile,the morphologies of the oxide scale formed on the surface of zirconium hydride were analyzed by scanning electron microscopy(SEM). The hydrogen desorption is retarded effectively when zirconium hydride is exposed to an oxygen containing atmosphere. Hydrogen desorption in mixed gas of helium and oxygen starts at 525 ℃ and reaches maximum at 660 ℃ and ends eventually at 800 ℃. No hydrogen desorption is found at the temperature range from 800 ℃ to 900 ℃. An oxide scale with approximately 20 μm in thickness formed on the surface of zirconium hydride acts as an effective diffusion barrier.展开更多
The rare earth based hydrogen storage alloys Mm_xMl_ 1-xNi_ 3.55Co_ 0.75Mn_ 0.4Al_ 0.3(x=0～0.50) were investigated in this work. The influences of phase structure on the PCT characteristics were analyzed by means of ...The rare earth based hydrogen storage alloys Mm_xMl_ 1-xNi_ 3.55Co_ 0.75Mn_ 0.4Al_ 0.3(x=0～0.50) were investigated in this work. The influences of phase structure on the PCT characteristics were analyzed by means of electrochemical measurements. The results indicate that there is a strict relationship between crystal volume and PCT characteristics.展开更多
文摘The equilibrium and kinetics of methyl isobutyl ketone(MIBK) extraction resin for adsorption and separation of zirconium and hafnium were studied under the different conditions of acidity,initial total concentrations of zirconium and hafnium and temperature.The equilibrium data of both zirconium and hafnium are found to follow the Freundlich adsorption isotherm,and the Freundlich isotherm constants(KF) are 3.53 and 0.64 mg/g,respectively.The equilibrium data of zirconium also fit the Langmuir adsorption isotherm,and the saturation adsorption capacity(Qmax) and the Langmuir isotherm constant(KL)are 75.93 mg/g and-0.012 7 L/g,respectively.The obtained kinetic data of both zirconium and hafnium are found to fit the HO pseudo-second-order kinetic model,and the rate constants of pseudo-second-order equation(k2) are-0.019 and 0.41 g/(mg·min),respectively.Column tests show that the MIBK extraction resin could be used as efficient adsorbent material for separating hafnium from zirconium.
文摘The electrochemical reduction of Zr^4＋（complex） ions in NaCl-KCl-K2ZrF6 molten salt on Pt electrode was investigated using cyclic voltammetry and square wave voltammetry at 1023 K.Two cathodic reduction peaks related to Zr^4＋/Zr^2＋ and Zr^2＋/Zr steps were observed in the cyclic voltammograms.The result was also confirmed by square wave voltammetry.The diffusion coefficient of Zr^4＋（complex） ions at 1023 K in NaCl-KCl-K2ZrF6 melt,measured by cyclic voltammetry,is about 4.22×10^-6 cm^2/s.The characterization of the deposits obtained by potentiostatic electrolysis at different potentials was investigated by XRD,and the results were well consistent with the electrochemical reduction mechanism of Zr^4＋（complex） ions.
基金the National Natural Science Foundation of China (No. 50674015)
文摘A hydrogen permeation barrier was manufactured by the in situ reaction of zirconium hydride with oxygen. A reduction in the hydrogen permeation of the oxide films was detected by measuring the mass difference of the zirconium hydride samples after the dehydrogenation experiment. The reaction of zirconium hydride with oxygen occurs only under the condition that the temperature is higher than 673 K in the oxygen partial pressure of 0.1 MPa. The oxide film is composed of two layers, a permeable oxide layer and a dense oxide layer, and the main phase of the oxide film is ZrO2 with baddeleyite structure. The XPS analysis shows that O-H bonds exist in the oxide film, which are helpful for resisting hydrogen diffusion through the oxide film.
文摘The recovery of nickel from laterite ore with sulphuric acid under the effect of microwave irradiation was studied.The experimental results indicated that the extraction rate of nickel was influenced by reaction time,sulphuric acid concentration,and temperature,especially by microwave power.The results obtained from the experiments of orthogonal arrays showed that the optimum conditions of sulphuric acid concentration,reaction time,microwave power,and temperature were 25 vol.%,1.5 h,600 W,and 90°C,respectively.Under the optimal conditions,the nickel recovery could reach approximately 90.8%,which was higher than that obtained by conventional water bath heating.Kinetic experiments showed that the leaching of nickel in a sulphuric acid medium was controlled by chemical reaction occurring on the surface of laterite ore.The apparent activation energy was 38.9 kJ/mol.Microwave heating technology is efficient,clean,and easy to control and facilitate continuous processing of materials.
文摘The decomposition process for zircon sand concentrate using mixed base of sodium hydroxide partly replaced by calcium oxide was inrestigated.It is found that the decomposition rate of zircon gradually increased with the increase of the reaction temperature and time.The decomposition rate is over 97% with the conditions that CaO/zircon molar ratio is 0.25 ～ 0.75 at 800 ℃ for 1 h.Whereas the decomposition rate decreased when the molar ratio was more than 0.75.Also,thermogravimetry-differential thermal analysis(TG-DTA) and X-ray diffraction(XRD) were used to study the reaction mechanism of zircon decomposition process with CaO-NaOH.The results showed that Na_2O,which was generated by the reaction of CaO and Na_4SiO_4,increased the decomposition rate of zircon owing to its spread to the surface of zircon and played a role in decomposition process.
基金financially supported by the National Natural Science Foundation (Nos. 51164023 and 513640236)the Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region (No. NJYT-13B10)the Program for New Century Excellent Talents in University (No. NCET-13-0847)。
文摘ZrO_(2)ceramic coatings were directly prepared on the surface of ZrH_(1.8) in silicate and phosphate elec-trolytes by micro-arc oxidation(MAO)technique,respec-tively.The microstructure,chemical composition and phase composition of ZrO_(2)ceramic coatings were inves-tigated by X-ray diffraction(XRD),energy-dispersive spectrometry(EDS)and scanning electron microscopy(SEM).The anti-permeation effect was measured by means of vacuum dehydrogenation experiment.It is found that the coating fabricated in phosphate electrolyte is more compact than that in silicate electrolyte.The coatings fabricated on the surface of ZrH_(1.8) are composed of M-ZrO_(2),T-ZrO_(2) and C-ZrO_(2).EDS analysis indicates that the coatings are mainly composed of O and Zr.Vacuum dehydrogenation experiment shows that the permeation reduction factor(PRF)of coating prepared in phosphate electrolyte is su-perior to that in the silicate electrolyte,and the PRF value reaches up to 11.2,which can enhance the resistance effect of hydrogen significantly.
文摘Modified lithium manganese oxides were prepared by solid-state reaction of LiMn_(2)O_(4)and LiCoO_(2)as raw materials.A study was carried out by TG-DSC,XRD,DSC and electrochemical to analyse the reaction process and structural characterization of products.The results show that the LiMn_(2)O_(4)reacts chemically with LiCoO_(2)at high temperature.All of Li and partial Co atoms can insert into the LiMn_(2)O_(4)crystal lattice and a newly formed spinel phase-modified LiMn_(2)O_(4)was obtained.The distribution of Co content is even in modified LiMn_(2)O_(4)compound.The modified LiMn_(2)O_(4)compound exhibits improved cycling stability at room and elevated temperature in comparison with the pure LiMn_(2)O_(4).
基金financially supported by the National Natural Science Foundation (Nos. 51164023 and 51364026)the Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region (No. NJYT-13B10)+1 种基金the New Century Excellent Talents in University (No.NCET13-0847)the Inner Mongolia Natural Science Fund Project (No. 2011MS0709)
文摘The present work aims to present the micro-arc oxidation(MAO)zirconia coating with superior compact-ness and moderate thickness on zirconium hydride.The experiments were designed according to L16(44)orthog-onal array to optimize electrical parameters(frequency,negative voltage,positive voltage and MAO time),with four levels of each factor.The optimized value was pre-dicted and verified by the confirmation experiment.The anti-permeation effect was tested by means of vacuum dehydrogenation experiment.The optimized coating parameters are listed as follows:treating time of 25 min,frequency of 200 Hz,negative voltage of 150 V and pos-itive voltage of 380 V.Experimental results show that the optimized coating exhibits the highest compactness of 0.3705 mg·μm^(-1).This dense coating significantly enhan-ces the hydrogen anti-permeation effects,and the PRF value is improved by nearly 13 times in contrast with that of uncoated ZrH_(1.8).
基金Project(50674015) supported by the National Natural Science Foundation of China
文摘Hydrogen desorption behaviors of zirconium hydride at temperature range of 100-900 ℃ in mixture gases of helium and oxygen was studied by gas phase analysis(GPA). Meanwhile,the morphologies of the oxide scale formed on the surface of zirconium hydride were analyzed by scanning electron microscopy(SEM). The hydrogen desorption is retarded effectively when zirconium hydride is exposed to an oxygen containing atmosphere. Hydrogen desorption in mixed gas of helium and oxygen starts at 525 ℃ and reaches maximum at 660 ℃ and ends eventually at 800 ℃. No hydrogen desorption is found at the temperature range from 800 ℃ to 900 ℃. An oxide scale with approximately 20 μm in thickness formed on the surface of zirconium hydride acts as an effective diffusion barrier.
文摘The rare earth based hydrogen storage alloys Mm_xMl_ 1-xNi_ 3.55Co_ 0.75Mn_ 0.4Al_ 0.3(x=0～0.50) were investigated in this work. The influences of phase structure on the PCT characteristics were analyzed by means of electrochemical measurements. The results indicate that there is a strict relationship between crystal volume and PCT characteristics.
