In this study,a novel hydrometallurgical process consisting of hydrochloric acid three-stage countercurrent leaching and solvent extraction was proposed to recover rare earth oxide(REO)from the rare earth polishing po...In this study,a novel hydrometallurgical process consisting of hydrochloric acid three-stage countercurrent leaching and solvent extraction was proposed to recover rare earth oxide(REO)from the rare earth polishing powder waste(REPPW).The effects of HCl concentration,liquid-solid ratio(L/S ratio),temperature and time on the leaching yields of rare earths(in REO)and aluminum(in Al2O3)were studied.The result shows that the leaching yields of REO and Al2O3 are 90.96%and 43.89%respectively under the optimum leaching parameters of HCl concentration=8.00 mol/L,L/S ratio=4 mL/g,leaching temperature=353 K and leaching time=180 min.Meanwhile,the leaching kinetics of REO and Al2O3 were investigated in this study.The leaching behaviors of REO and Al2O3 follow a shrinking sphere/core model and the general leaching process is controlled by the surface chemical reaction.The leaching activation energies of REO and Al2O3 are 9.86 and 13.68 kJ/mol,respectively.The leaching yield of each substance in three-stage countercurrent leaching is improved substantially compared with single-stage leaching,with a change from 90.96%to 95.38%for REO and from 43.89%to 46.22%for Al2O3,respectively.Especially,the total concentration of REO in three-stage countercurrent leaching solution is greatly increased to above 300 g/L,and the acidity of which is decreased to ca.pH=2,which is conducive to subsequent solvent extraction directly.High purity REO(99.92%)is obtained by solvent extraction separation,oxalate precipitation and calcination.The total recovery yield of REO is 85.13%.展开更多
The ozonolysis of 2,3,7,8-tetra-chlorodibenzo-p-dioxin （2,3,7,8-TCDD） is an efficient degradation way in the atmosphere. The ozonolysis process and possible reactions path of Criegee Intermediates with NO and H2O ar...The ozonolysis of 2,3,7,8-tetra-chlorodibenzo-p-dioxin （2,3,7,8-TCDD） is an efficient degradation way in the atmosphere. The ozonolysis process and possible reactions path of Criegee Intermediates with NO and H2O are introduced in detail at the method of MPWB1K/6-31＋G（d,p）//MPWB1K/6- 311＋G（3df,2p） level. In ozonolysis, H2O is an important source of OH radical formation and initiated the subsequent degradation reaction. The Rice-Ramsperger-Kassel-Marcus （RRKM） theory was applied to calculate rate constants with the temperature ranging from 200 to 600 K. The rate constant of reaction between 2,3,7,8-TCDD and 03 is 4.80 × 10^-20 cm3/（mole.sec） at 298 K and 760 Tort. The atmospheric lifetime of the reaction species was estimated according to rate constants, which is helpful for the atmospheric model study on the degradation and risk assessment of dioxin.展开更多
Mevinolin is one of the earlier statin drugs which is effective for the treatment of hypercholesterolemia, as an inhibitor of the HMG-CoA reductase. The transformations of mevinolin in acidic alcohol（ such as ethanol...Mevinolin is one of the earlier statin drugs which is effective for the treatment of hypercholesterolemia, as an inhibitor of the HMG-CoA reductase. The transformations of mevinolin in acidic alcohol（ such as ethanol, methanol and isopropanol） solutions caused by solvent effects were revealed in the present article. The solvates, that is, mevinolinic methyl ester, mevinolinic ethyl ester and mevinolinic isopropyl ester, were identified by LC/PDA and LC/MS. The kinetics parameters of the transformations caused by solvent effects, such as the observed rate constant of mevinolin （kobs）, the maximum concentration（ Cmax ）, and its corresponding maximum time（ t time for the acid form to reach the maximum concentration） of mevinolinic acid, are discussed. The influencing factors, such as the kind of solvents, the acidic concentration, the initial mevinolin concentration, and the water content as well as temperature were investigated. Two kinds of comparative reactions, hydrolysis and alcoholysis, of mevinolin in solution were studied. This detailed study on the kinetics of mevinolin transformations is valuable and meaningful for the purification, preparation, injection manufacturing, extraction, storage, etc. , of mevinolin or other similar compounds. This work provides useful information for the quality control of mevinolin and mevinolin-like drugs as well.展开更多
Kinetic knowledge is of great importance in achieving good control of the pyrolysis and gasification process and optimising system design. An overall kinetic pyrolysis scheme is therefore addressed here. The ki-net...Kinetic knowledge is of great importance in achieving good control of the pyrolysis and gasification process and optimising system design. An overall kinetic pyrolysis scheme is therefore addressed here. The ki-netic modelling incorporates the following basic steps: the degradation of the virgin biomass materials into pri-mary products ( tar, gas and semi-char), the decomposition of primary tar into secondary products and the continuous interaction between primary gas and char. The last step is disregarded completely by models in the literature. Analysis and comparison of predicted results from different kinetic schemes and experimental data on our fixed bed pyrolyser yielded very positive evidence to support our kinetic scheme.展开更多
In this work,characterization and kinetics of CO2 absorption in potassium carbonate(K_(2)CO_(3))solution promoted by diethylenetriamine(DETA)were investigated.Kinetics measurements were performed using a stirred cell ...In this work,characterization and kinetics of CO2 absorption in potassium carbonate(K_(2)CO_(3))solution promoted by diethylenetriamine(DETA)were investigated.Kinetics measurements were performed using a stirred cell reactor in the temperature range of 303.15–323.15 K and total concentration up to 2.5 kmol m3.The density,viscosity,physical solubility,CO_(2) diffusivity and absorption rate of CO_(2) in the solution were determined.The reaction kinetics between CO_(2) and K2CO3þDETA solution were examined.Pseudo-first order kinetic constants were also predicted by zwitterion mechanism.It was revealed that the addition of small amounts of DETA to K_(2)CO_(3) results in a significant enhancement in CO_(2) absorption rate.The reaction order and activation energy were found to be 1.6 and 35.6 kJ mol1,respectively.In terms of reaction rate constant,DETA showed a better performance compared to the other promoters such as MEA,EAE,proline,arginine,taurine,histidine and alanine.展开更多
A green environmental protection and enhanced leaching process was proposed to recover all elements from spent lithium iron phosphate(LiFePO_(4)) lithium batteries.In order to reduce the influence of Al impurity in th...A green environmental protection and enhanced leaching process was proposed to recover all elements from spent lithium iron phosphate(LiFePO_(4)) lithium batteries.In order to reduce the influence of Al impurity in the recovery process,NaOH was used to remove impurity.After impurity removal,the spent LiFePO_(4) cathode material was used as raw material under the H_(2)SO_(4) system,and the pressure oxidation leaching process was adopted to achieve the preferential leaching of lithium.The E-pH diagram of the Fe-P-Al-H_(2)O system can determine the stable region of each element in the recovery process of spent LiFePO_(4)Li-batteries.Under the optimal conditions(500 r·min^(-1),15 h,363.15 K,0.4 MPa,the liquid-solid ratio was 4:1 ml·g^(-1)and the acid-material ratio was 0.29),the leaching rate of Li was 99.24%,Fe,Al,and Ti were 0.10%,2.07%,and 0.03%,respectively.The Fe and P were precipitated and recovered as FePO_(4)·2H_(2)O.The kinetic analysis shows that the process of high-pressure acid leaching of spent LiFePO_(4) materials depends on the surface chemical reaction.Through the life cycle assessment(LCA)of the spent LiFePO_(4) whole recovery process,eight midpoint impact categories were selected to assess the impact of recovery process.The results can provide basic environmental information on production process for recycling industry.展开更多
The mechanical performance of flexible catalysts remains a significant challenge for industrial applications.In this study,graphene oxide(GO)functions as both a binder and a redox mediator,serving as a crucial"br...The mechanical performance of flexible catalysts remains a significant challenge for industrial applications.In this study,graphene oxide(GO)functions as both a binder and a redox mediator,serving as a crucial"bridge"between metal species and the organic foam,thereby substantially enhancing NO_(x) conversion efficiency.Catalytic activity tests demonstrate that the GO-modified MnCo-MS@0.05GO catalyst achieves a NO_(x) conversion rate exceeding 95%.The incorporation of GO strengthens the adhesion between the organic foam and metal components,increases the surface roughness of the sponge,and ensures the uniform and stable distribution of metal active sites.Additionally,GO enhances the content of effective catalytic species,improves electron transfer efficiency in the selective catalytic reduction reaction,and reduces diffusion resistance.To elucidate the NO reduction mechanism,in situ diffuse reflectance infrared Fourier transform spectroscopy and transient reaction studies were performed.The results indicate that as the reaction temperature increases,both the Eley-Rideal and Langmuir-Hinshelwood mechanisms contribute to promoting the SCR reaction rate.展开更多
The kinetics and the mechanism of the formation reactions of M(PnAO)^(2+)(M=Ni,Co,Cu)were studied with UV Spectrophotometer and Stopped Flow Spectrophotometer and a three steps mechanism was suggested.
As a newly deVeloped method,high temperature in situ observation method can be used to observe directly the interface changes and study the kinetics mechanism during crystal growth.By our newly designed high temperatu...As a newly deVeloped method,high temperature in situ observation method can be used to observe directly the interface changes and study the kinetics mechanism during crystal growth.By our newly designed high temperature in situ observation equiPment,the interface changes of Bi_(12)SiO_(20) crystal growth from melt were studied.展开更多
In this paper, instead of with the more expensive Fourier Transform Infrared Spectrometer(FTIR) a new technique of Temperature Programmed Transient Response(TP-TR) has been used with gas chromatography. Therefore, the...In this paper, instead of with the more expensive Fourier Transform Infrared Spectrometer(FTIR) a new technique of Temperature Programmed Transient Response(TP-TR) has been used with gas chromatography. Therefore, the TP-TR will be applied more widespreadly than ever before. With the technique of TP-TR and electric conductivity, the study is on the reaction mechanism and the adsorption behavior of the reactants and products to the present catalyst Mo-V-Nb/Al_2O_3 in the reaction from ethane through oxydehydrogenation to ethylene as the product. By Range-Kutta-Gill and Margarat methods, the kinetic parameters of the reaction elementary steps (i.e. rate constants, active energies and frequency factors) have been evaluated. The mathematical treatment coincides with the experimental results.展开更多
The plasticizer is an important polymer material additive.Non-toxic and environmentally friendly plasticizers are developed recently in order to decrease fossil fuel reserves,serious environmental pollution and the to...The plasticizer is an important polymer material additive.Non-toxic and environmentally friendly plasticizers are developed recently in order to decrease fossil fuel reserves,serious environmental pollution and the toxicity of phthalate esters.In this study,a new,efficient and environmentally friendly plasticizer of hydrogenated rosin dodecyl ester was prepared by an esterification reaction of hydrogenated rosin and dodecanol.The influences of different reaction conditions(including different catalysts,the catalyst concentration,the ratio of the reactants,reaction temperature,and reaction time)on the esterification yield are examined and discussed.Hydrogenated rosin dodecyl ester with 71.8%yield was synthesized under the optimized reaction conditions(1:0.8 molar ratio of rosin to dodecanol,1 mol%tetrabutyl titanate concentration,and 210℃for 6 h).The esterification reaction is a second-order reaction,and kinetic calculations showed that the activation energy is 39.77 KJ·mol^(−1).The structure of the hydrogenated rosin dodecyl ester was confirmed by FT-IR spectroscopy and^(13)C NMR spectrum.Besides,the thermal stability of target product(hydrogenated rosin dodecyl ester)was also tested by thermal gravimetric analysis(TGA),which showed a good thermal stability.展开更多
The effective reuse of iron phosphate residue(IPR)is the key issue in the recycling of spent LiFePO_(4)batteries.Therefore,in this study,the reduction leaching of IPR in H_(2)SO_(4)solution by adding iron powder as re...The effective reuse of iron phosphate residue(IPR)is the key issue in the recycling of spent LiFePO_(4)batteries.Therefore,in this study,the reduction leaching of IPR in H_(2)SO_(4)solution by adding iron powder as reducing agent was investigated and compared with direct leaching.The results show that the leaching rate of IPR reached 97%under the optimum reduction leaching conditions.Kinetic studies show that the activation energy for reduction leaching is 12.71 k J/mol,while that of direct leaching is 21.57 k J/mol.Moreover,the reduction leaching time is reduced by half and the acid consumption is reduced by 30% compared to direct leaching with the same leaching rate.This work provides a scientific guidance to the treatment of iron phosphate residue from the recycling of spent LiFePO_(4)batteries.展开更多
The transformation of an anthraquinone dye blue 324 in a facultative-aerobic(F-A) system was investigated.Kinetic parameter study showed that higher Vmax coupled with more recalcitrant chemical oxygen demand(COD) were...The transformation of an anthraquinone dye blue 324 in a facultative-aerobic(F-A) system was investigated.Kinetic parameter study showed that higher Vmax coupled with more recalcitrant chemical oxygen demand(COD) were found in the facultative biofilm reactor(FBR) than in the aerobic reactor(AR).Results of the product analyses indicated that most of dye molecular could be facultatively broken down into simple intermediates,which would be further degraded under subsequent aerobic condition.The main metabolites in each reactor were detected by infrared(FT-IR) and high performance liquid chromatography and mass spectrometry(HPLC-MS).Comparison of the toxicities among the dye and its metabolites was conducted,surprisingly,the colorless intermediates from FBR possessed less inhibitory than original dye and the median effective luminescence concentration(EC50) in 15 min for aerobic effluent could not be detected,showing that hardly toxic products existed in the aerobic process effluent.展开更多
An efficient culture medium producing a bacterial elastase with high yields was developed further following preliminary studies by means of response surface method. Central composite design (CCD) and response surface ...An efficient culture medium producing a bacterial elastase with high yields was developed further following preliminary studies by means of response surface method. Central composite design (CCD) and response surface method-ology were applied to optimize the medium constituents. A central composite design was used to explain the combined effect of three medium constituents, viz, glucose, K2HPO4, MgSO47H2O. The strain produced more elastase in the completely optimized medium, as compared with the partially optimized medium. The fitted model of the second model, as per RSM, showed that glucose was 7.4 g/100 ml, casein 1.13 g/100 ml, corn steep flour 0.616 g/100 ml, K2HPO4 0.206 g/100 ml and MgSO47H2O 0.034 g/100 ml. The fermentation kinetics of these two culture media in the flask experiments were analyzed. It was found that the highest elastase productivity occurred at 54 hours. Higher glucose concentration had inhibitory effect on elastase production. At the same time, we observed that the glucose consumption rate was slow in the completely optimized medium, which can explain the lag period of the highest elastase production. Some metal ions and surfactant additives also affected elastase production and cell growth.展开更多
A simple model is described to simulate kinetic processes in dielectric barrier dis-charges for O2/NOx mixtures. A threshold of ozone production found experimentally is confirmedby the calculations of this modeling, a...A simple model is described to simulate kinetic processes in dielectric barrier dis-charges for O2/NOx mixtures. A threshold of ozone production found experimentally is confirmedby the calculations of this modeling, and the underiying chemical reaction mechanisms are dis-cussed. It is also found that the effects of diffusion processes in the period of the lifetime of Oatoms are not important to microdischarge channels with a large radius, i.e. larger than l50 μm.展开更多
Selective epoxidation of olefins is an important field in chemical industry.In this work,we developed a new phosphotungstic acid catalyst{[(C_8H_(17))(CH_(3))_(2)N]_(2)(CH_(2))_(3)}_(1.5){PO_(4)[WO(O_(2))_(2)]_(4)}wit...Selective epoxidation of olefins is an important field in chemical industry.In this work,we developed a new phosphotungstic acid catalyst{[(C_8H_(17))(CH_(3))_(2)N]_(2)(CH_(2))_(3)}_(1.5){PO_(4)[WO(O_(2))_(2)]_(4)}with long carbon chain and biquaternary ammonium cation.Cyclohexene could be epoxidized to cyclohexene oxide in 96.3%conversion and 98.2%selectivity.The catalyst type,solvent type,catalyst loading,initial molar ratio,temperature,cycle performance and substrate extensibility were studied and optimized,the kinetic parameters about overall reaction and unit reaction were also calculated.Dynamic light scattering analysis was carried out to explain the different catalytic performance between catalysts with different carbon chain length.This novel catalyst and the corresponding dynamics and mechanism study could probably help the industrial application on the epoxidation of cyclohexene with H_(2)O_(2).展开更多
The cementation reaction of copper on zinc metal in solutions of different concentrations ofcopper sulphate, at 25℃, has been studied and it is found to be a first order reaction. Moreover,the rates of this reaction ...The cementation reaction of copper on zinc metal in solutions of different concentrations ofcopper sulphate, at 25℃, has been studied and it is found to be a first order reaction. Moreover,the rates of this reaction at 0.15 mol'L-1 copper sulphate solution have been measured in a varietyof ethanol-water media at temperatures from 20℃ to 40℃. The correlation between the masstransfer coefficient and the dielectric constant has been investigated. Also, the thermodynamicparameters of activation have been calculated. The isokinetic relationship reveals the existenceof compensation effect, where the solute-solvent interactions play an important role.展开更多
Thermogravimetry(TG)analysis was applied for the pyrolysis of activated carbon from pistachio shell in a nitrogen atmosphere by physical activation and chemical activation using carbon dioxide and H3PO4.The kinetic st...Thermogravimetry(TG)analysis was applied for the pyrolysis of activated carbon from pistachio shell in a nitrogen atmosphere by physical activation and chemical activation using carbon dioxide and H3PO4.The kinetic study was accomplished using TG curves based on weight loss as a function of temperature.TG experiments were performed under nitrogen atmosphere(100 ML/min)and a linear heating rate of 20℃/min up to 850℃.Differential thermogravimetric(DTG)data were analyzed using an Arrhenius type reaction model assuming a first-order reaction.Kinetic parameters including activation energy,Ea,and pre-exponential factor,A,for this activated carbon was determined.The activation energy(E,,=172.25 k J/tool)and maximum rate temperature(Rt=670℃)were approximately in the ranges of Ea values from previous studies using types of activated carbon with values between 100-300 kJ/mol.The thermodynamic parameters of activation,△Gc=220.51 kJ/mol,△Hf=164.42 kJ/mol and△Sc=-59.48 J/tool K,were obtained.These quantities indicated the obtained activated carbon from pistachio shell is stable but the rate of the pyrolysis is slow at low temperatures.展开更多
基金Project supported by National High-tech Research and Development Program(2017AA031002)。
文摘In this study,a novel hydrometallurgical process consisting of hydrochloric acid three-stage countercurrent leaching and solvent extraction was proposed to recover rare earth oxide(REO)from the rare earth polishing powder waste(REPPW).The effects of HCl concentration,liquid-solid ratio(L/S ratio),temperature and time on the leaching yields of rare earths(in REO)and aluminum(in Al2O3)were studied.The result shows that the leaching yields of REO and Al2O3 are 90.96%and 43.89%respectively under the optimum leaching parameters of HCl concentration=8.00 mol/L,L/S ratio=4 mL/g,leaching temperature=353 K and leaching time=180 min.Meanwhile,the leaching kinetics of REO and Al2O3 were investigated in this study.The leaching behaviors of REO and Al2O3 follow a shrinking sphere/core model and the general leaching process is controlled by the surface chemical reaction.The leaching activation energies of REO and Al2O3 are 9.86 and 13.68 kJ/mol,respectively.The leaching yield of each substance in three-stage countercurrent leaching is improved substantially compared with single-stage leaching,with a change from 90.96%to 95.38%for REO and from 43.89%to 46.22%for Al2O3,respectively.Especially,the total concentration of REO in three-stage countercurrent leaching solution is greatly increased to above 300 g/L,and the acidity of which is decreased to ca.pH=2,which is conducive to subsequent solvent extraction directly.High purity REO(99.92%)is obtained by solvent extraction separation,oxalate precipitation and calcination.The total recovery yield of REO is 85.13%.
基金supported by National Natural Science Foundation of China(No.21277082,21177076,71201093)the Promotive Research Fund for Excellent Young and Middle-aged Scientists of Shandong Province(No.BS2012HZ009,BS2012SF012)+2 种基金the Hi-Tech Research and Development Program(863)of China(No.2012AA06A301)the New Century Excellent Talents in University(NCET-13-0349)the Open Project from special fund of State Key Joint Laboratory of Environment Simulation and Pollution Control(No.13K05ESPCP)
文摘The ozonolysis of 2,3,7,8-tetra-chlorodibenzo-p-dioxin （2,3,7,8-TCDD） is an efficient degradation way in the atmosphere. The ozonolysis process and possible reactions path of Criegee Intermediates with NO and H2O are introduced in detail at the method of MPWB1K/6-31＋G（d,p）//MPWB1K/6- 311＋G（3df,2p） level. In ozonolysis, H2O is an important source of OH radical formation and initiated the subsequent degradation reaction. The Rice-Ramsperger-Kassel-Marcus （RRKM） theory was applied to calculate rate constants with the temperature ranging from 200 to 600 K. The rate constant of reaction between 2,3,7,8-TCDD and 03 is 4.80 × 10^-20 cm3/（mole.sec） at 298 K and 760 Tort. The atmospheric lifetime of the reaction species was estimated according to rate constants, which is helpful for the atmospheric model study on the degradation and risk assessment of dioxin.
基金Supported by Shanghai Leading Discipline Project(No. Y0301) and the Funds of Shanghai Scientific and Technology Develop-ment(No. 03DZ19546)
文摘Mevinolin is one of the earlier statin drugs which is effective for the treatment of hypercholesterolemia, as an inhibitor of the HMG-CoA reductase. The transformations of mevinolin in acidic alcohol（ such as ethanol, methanol and isopropanol） solutions caused by solvent effects were revealed in the present article. The solvates, that is, mevinolinic methyl ester, mevinolinic ethyl ester and mevinolinic isopropyl ester, were identified by LC/PDA and LC/MS. The kinetics parameters of the transformations caused by solvent effects, such as the observed rate constant of mevinolin （kobs）, the maximum concentration（ Cmax ）, and its corresponding maximum time（ t time for the acid form to reach the maximum concentration） of mevinolinic acid, are discussed. The influencing factors, such as the kind of solvents, the acidic concentration, the initial mevinolin concentration, and the water content as well as temperature were investigated. Two kinds of comparative reactions, hydrolysis and alcoholysis, of mevinolin in solution were studied. This detailed study on the kinetics of mevinolin transformations is valuable and meaningful for the purification, preparation, injection manufacturing, extraction, storage, etc. , of mevinolin or other similar compounds. This work provides useful information for the quality control of mevinolin and mevinolin-like drugs as well.
文摘Kinetic knowledge is of great importance in achieving good control of the pyrolysis and gasification process and optimising system design. An overall kinetic pyrolysis scheme is therefore addressed here. The ki-netic modelling incorporates the following basic steps: the degradation of the virgin biomass materials into pri-mary products ( tar, gas and semi-char), the decomposition of primary tar into secondary products and the continuous interaction between primary gas and char. The last step is disregarded completely by models in the literature. Analysis and comparison of predicted results from different kinetic schemes and experimental data on our fixed bed pyrolyser yielded very positive evidence to support our kinetic scheme.
文摘In this work,characterization and kinetics of CO2 absorption in potassium carbonate(K_(2)CO_(3))solution promoted by diethylenetriamine(DETA)were investigated.Kinetics measurements were performed using a stirred cell reactor in the temperature range of 303.15–323.15 K and total concentration up to 2.5 kmol m3.The density,viscosity,physical solubility,CO_(2) diffusivity and absorption rate of CO_(2) in the solution were determined.The reaction kinetics between CO_(2) and K2CO3þDETA solution were examined.Pseudo-first order kinetic constants were also predicted by zwitterion mechanism.It was revealed that the addition of small amounts of DETA to K_(2)CO_(3) results in a significant enhancement in CO_(2) absorption rate.The reaction order and activation energy were found to be 1.6 and 35.6 kJ mol1,respectively.In terms of reaction rate constant,DETA showed a better performance compared to the other promoters such as MEA,EAE,proline,arginine,taurine,histidine and alanine.
基金supported by the National Natural Science Foundation of China(51834008,52022109,52274307,and 21804319)National Key Research and Development Program of China(2021YFC2901100)+1 种基金Science Foundation of China University of Petroleum,Beijing(2462022QZDX008,2462021QNX2010,2462020YXZZ019 and 2462020YXZZ016)State Key Laboratory of Heavy Oil Processing(HON-KFKT2022-10).
文摘A green environmental protection and enhanced leaching process was proposed to recover all elements from spent lithium iron phosphate(LiFePO_(4)) lithium batteries.In order to reduce the influence of Al impurity in the recovery process,NaOH was used to remove impurity.After impurity removal,the spent LiFePO_(4) cathode material was used as raw material under the H_(2)SO_(4) system,and the pressure oxidation leaching process was adopted to achieve the preferential leaching of lithium.The E-pH diagram of the Fe-P-Al-H_(2)O system can determine the stable region of each element in the recovery process of spent LiFePO_(4)Li-batteries.Under the optimal conditions(500 r·min^(-1),15 h,363.15 K,0.4 MPa,the liquid-solid ratio was 4:1 ml·g^(-1)and the acid-material ratio was 0.29),the leaching rate of Li was 99.24%,Fe,Al,and Ti were 0.10%,2.07%,and 0.03%,respectively.The Fe and P were precipitated and recovered as FePO_(4)·2H_(2)O.The kinetic analysis shows that the process of high-pressure acid leaching of spent LiFePO_(4) materials depends on the surface chemical reaction.Through the life cycle assessment(LCA)of the spent LiFePO_(4) whole recovery process,eight midpoint impact categories were selected to assess the impact of recovery process.The results can provide basic environmental information on production process for recycling industry.
文摘The mechanical performance of flexible catalysts remains a significant challenge for industrial applications.In this study,graphene oxide(GO)functions as both a binder and a redox mediator,serving as a crucial"bridge"between metal species and the organic foam,thereby substantially enhancing NO_(x) conversion efficiency.Catalytic activity tests demonstrate that the GO-modified MnCo-MS@0.05GO catalyst achieves a NO_(x) conversion rate exceeding 95%.The incorporation of GO strengthens the adhesion between the organic foam and metal components,increases the surface roughness of the sponge,and ensures the uniform and stable distribution of metal active sites.Additionally,GO enhances the content of effective catalytic species,improves electron transfer efficiency in the selective catalytic reduction reaction,and reduces diffusion resistance.To elucidate the NO reduction mechanism,in situ diffuse reflectance infrared Fourier transform spectroscopy and transient reaction studies were performed.The results indicate that as the reaction temperature increases,both the Eley-Rideal and Langmuir-Hinshelwood mechanisms contribute to promoting the SCR reaction rate.
文摘The kinetics and the mechanism of the formation reactions of M(PnAO)^(2+)(M=Ni,Co,Cu)were studied with UV Spectrophotometer and Stopped Flow Spectrophotometer and a three steps mechanism was suggested.
文摘As a newly deVeloped method,high temperature in situ observation method can be used to observe directly the interface changes and study the kinetics mechanism during crystal growth.By our newly designed high temperature in situ observation equiPment,the interface changes of Bi_(12)SiO_(20) crystal growth from melt were studied.
文摘In this paper, instead of with the more expensive Fourier Transform Infrared Spectrometer(FTIR) a new technique of Temperature Programmed Transient Response(TP-TR) has been used with gas chromatography. Therefore, the TP-TR will be applied more widespreadly than ever before. With the technique of TP-TR and electric conductivity, the study is on the reaction mechanism and the adsorption behavior of the reactants and products to the present catalyst Mo-V-Nb/Al_2O_3 in the reaction from ethane through oxydehydrogenation to ethylene as the product. By Range-Kutta-Gill and Margarat methods, the kinetic parameters of the reaction elementary steps (i.e. rate constants, active energies and frequency factors) have been evaluated. The mathematical treatment coincides with the experimental results.
基金the financial support From the Open Fund Project of Key Lab.of Biomass Energy and Material,Jiangsu Province(JSBEM201907)the Ordinary University Young Innovative Talents Project of Guangdong Province(2018KQNCX119)+4 种基金Provincial Science and Technology Planning Projects of Guangdong Province(2017A040405055)Guangdong-Hong Kong Cooperation Project(2017A050506055)Guangdong Provincial Education Department Project(Natural Science,2017KZDXM045)Guangzhou major special project for collaborative innovation of industry,University and research(201604020074)the fund project of Yele Science and Technology Innovation(YL201807).
文摘The plasticizer is an important polymer material additive.Non-toxic and environmentally friendly plasticizers are developed recently in order to decrease fossil fuel reserves,serious environmental pollution and the toxicity of phthalate esters.In this study,a new,efficient and environmentally friendly plasticizer of hydrogenated rosin dodecyl ester was prepared by an esterification reaction of hydrogenated rosin and dodecanol.The influences of different reaction conditions(including different catalysts,the catalyst concentration,the ratio of the reactants,reaction temperature,and reaction time)on the esterification yield are examined and discussed.Hydrogenated rosin dodecyl ester with 71.8%yield was synthesized under the optimized reaction conditions(1:0.8 molar ratio of rosin to dodecanol,1 mol%tetrabutyl titanate concentration,and 210℃for 6 h).The esterification reaction is a second-order reaction,and kinetic calculations showed that the activation energy is 39.77 KJ·mol^(−1).The structure of the hydrogenated rosin dodecyl ester was confirmed by FT-IR spectroscopy and^(13)C NMR spectrum.Besides,the thermal stability of target product(hydrogenated rosin dodecyl ester)was also tested by thermal gravimetric analysis(TGA),which showed a good thermal stability.
基金financial support from the Hunan Provincial Natural Science Foundation,China(No.2022JJ10074)。
文摘The effective reuse of iron phosphate residue(IPR)is the key issue in the recycling of spent LiFePO_(4)batteries.Therefore,in this study,the reduction leaching of IPR in H_(2)SO_(4)solution by adding iron powder as reducing agent was investigated and compared with direct leaching.The results show that the leaching rate of IPR reached 97%under the optimum reduction leaching conditions.Kinetic studies show that the activation energy for reduction leaching is 12.71 k J/mol,while that of direct leaching is 21.57 k J/mol.Moreover,the reduction leaching time is reduced by half and the acid consumption is reduced by 30% compared to direct leaching with the same leaching rate.This work provides a scientific guidance to the treatment of iron phosphate residue from the recycling of spent LiFePO_(4)batteries.
基金Natural Science Foundation of Shanghai,China (No.06ZR14002)Shanghai Leading Academic Discipline Project (No.B604)
文摘The transformation of an anthraquinone dye blue 324 in a facultative-aerobic(F-A) system was investigated.Kinetic parameter study showed that higher Vmax coupled with more recalcitrant chemical oxygen demand(COD) were found in the facultative biofilm reactor(FBR) than in the aerobic reactor(AR).Results of the product analyses indicated that most of dye molecular could be facultatively broken down into simple intermediates,which would be further degraded under subsequent aerobic condition.The main metabolites in each reactor were detected by infrared(FT-IR) and high performance liquid chromatography and mass spectrometry(HPLC-MS).Comparison of the toxicities among the dye and its metabolites was conducted,surprisingly,the colorless intermediates from FBR possessed less inhibitory than original dye and the median effective luminescence concentration(EC50) in 15 min for aerobic effluent could not be detected,showing that hardly toxic products existed in the aerobic process effluent.
文摘An efficient culture medium producing a bacterial elastase with high yields was developed further following preliminary studies by means of response surface method. Central composite design (CCD) and response surface method-ology were applied to optimize the medium constituents. A central composite design was used to explain the combined effect of three medium constituents, viz, glucose, K2HPO4, MgSO47H2O. The strain produced more elastase in the completely optimized medium, as compared with the partially optimized medium. The fitted model of the second model, as per RSM, showed that glucose was 7.4 g/100 ml, casein 1.13 g/100 ml, corn steep flour 0.616 g/100 ml, K2HPO4 0.206 g/100 ml and MgSO47H2O 0.034 g/100 ml. The fermentation kinetics of these two culture media in the flask experiments were analyzed. It was found that the highest elastase productivity occurred at 54 hours. Higher glucose concentration had inhibitory effect on elastase production. At the same time, we observed that the glucose consumption rate was slow in the completely optimized medium, which can explain the lag period of the highest elastase production. Some metal ions and surfactant additives also affected elastase production and cell growth.
文摘A simple model is described to simulate kinetic processes in dielectric barrier dis-charges for O2/NOx mixtures. A threshold of ozone production found experimentally is confirmedby the calculations of this modeling, and the underiying chemical reaction mechanisms are dis-cussed. It is also found that the effects of diffusion processes in the period of the lifetime of Oatoms are not important to microdischarge channels with a large radius, i.e. larger than l50 μm.
基金supported by Natural Science Foundation of Jiangsu Province(BK20210185)National Natural Science Foundation of China(21776122)。
文摘Selective epoxidation of olefins is an important field in chemical industry.In this work,we developed a new phosphotungstic acid catalyst{[(C_8H_(17))(CH_(3))_(2)N]_(2)(CH_(2))_(3)}_(1.5){PO_(4)[WO(O_(2))_(2)]_(4)}with long carbon chain and biquaternary ammonium cation.Cyclohexene could be epoxidized to cyclohexene oxide in 96.3%conversion and 98.2%selectivity.The catalyst type,solvent type,catalyst loading,initial molar ratio,temperature,cycle performance and substrate extensibility were studied and optimized,the kinetic parameters about overall reaction and unit reaction were also calculated.Dynamic light scattering analysis was carried out to explain the different catalytic performance between catalysts with different carbon chain length.This novel catalyst and the corresponding dynamics and mechanism study could probably help the industrial application on the epoxidation of cyclohexene with H_(2)O_(2).
文摘The cementation reaction of copper on zinc metal in solutions of different concentrations ofcopper sulphate, at 25℃, has been studied and it is found to be a first order reaction. Moreover,the rates of this reaction at 0.15 mol'L-1 copper sulphate solution have been measured in a varietyof ethanol-water media at temperatures from 20℃ to 40℃. The correlation between the masstransfer coefficient and the dielectric constant has been investigated. Also, the thermodynamicparameters of activation have been calculated. The isokinetic relationship reveals the existenceof compensation effect, where the solute-solvent interactions play an important role.
文摘Thermogravimetry(TG)analysis was applied for the pyrolysis of activated carbon from pistachio shell in a nitrogen atmosphere by physical activation and chemical activation using carbon dioxide and H3PO4.The kinetic study was accomplished using TG curves based on weight loss as a function of temperature.TG experiments were performed under nitrogen atmosphere(100 ML/min)and a linear heating rate of 20℃/min up to 850℃.Differential thermogravimetric(DTG)data were analyzed using an Arrhenius type reaction model assuming a first-order reaction.Kinetic parameters including activation energy,Ea,and pre-exponential factor,A,for this activated carbon was determined.The activation energy(E,,=172.25 k J/tool)and maximum rate temperature(Rt=670℃)were approximately in the ranges of Ea values from previous studies using types of activated carbon with values between 100-300 kJ/mol.The thermodynamic parameters of activation,△Gc=220.51 kJ/mol,△Hf=164.42 kJ/mol and△Sc=-59.48 J/tool K,were obtained.These quantities indicated the obtained activated carbon from pistachio shell is stable but the rate of the pyrolysis is slow at low temperatures.
