The continuous affinity- recycle extraction (CARE) process is extended ic a system with ultrafiltration membranes. The mathematical model of the process is established by taking into account membrane rejections to th...The continuous affinity- recycle extraction (CARE) process is extended ic a system with ultrafiltration membranes. The mathematical model of the process is established by taking into account membrane rejections to the components in a crude mixture. The process performance, defined as concentration factor (CF ), purification factor (PF ) and recovery yield (REC), is analyzed by computer simulations. The results show that CF and REC increase, but PF decreases with the membrane rejection. It is likely that optimum operating conditions exist to give the best process performance because the increases in eluant and affinity-recycle flow rate improve REC but decrease PF.展开更多
Single step and multi step CARE processes are optimized by computer simulations based on the mathematical model proposed previously. The product of purification factor and recovery yield is used as the objective fun...Single step and multi step CARE processes are optimized by computer simulations based on the mathematical model proposed previously. The product of purification factor and recovery yield is used as the objective function for optimizing a single step process. The objective function for the optimization of a multi step process is considered to obtain an anticipated product purity at a maximum recovery yield and a minimum number of CARE inividuals. Pairs of the operating conditions (eluant and affinity recycle flow rates) exist to give the maximums of above objective functions when membrane rejections to ligates and contaminants are equal in value. The optimum affinity recycle flow rate decreases with the increase of membrane rejections and equilibrium binding fractions of ligates. For a multi step process, when contaminants are rejected less than ligate, only one pair of the optimum eluant and affinity recycle flow rates exists.展开更多
NaxCoO2 is a commonly used cathode material for sodium ion batteries because of its easy synthesis, high reversible capacity and good cyclability. The structural and electrochemical properties of NaxCoO2 during sodium...NaxCoO2 is a commonly used cathode material for sodium ion batteries because of its easy synthesis, high reversible capacity and good cyclability. The structural and electrochemical properties of NaxCoO2 during sodium ion insertion/extraction process are studied based on first principles calculations. The calculation results of crystal structure parameters and average intercalation voltage are in good agreement with experiment data. Through calculation of the geometric structure and charge transfer in charging and discharging processes of NaxCoO2, it is found that the oxygen atom surrounding Co of the CoO6 octahedral screens the coulomb potential produced by sodium vacancy in NaxCoO2, and the charge is removed from the entire Co-O layer instead of the Co atom adjacent to sodium vacancy when sodium ions are extracted from the Na CoO2 lattice. Thus, during the insertion/extraction of sodium ion from Na CoO2, the CoO6 octahedral structure undergoes small lattice distortion, which makes the local structure quite stable and is beneficial to the cycling stability of the material for the application of sodium ion batteries.展开更多
文摘The continuous affinity- recycle extraction (CARE) process is extended ic a system with ultrafiltration membranes. The mathematical model of the process is established by taking into account membrane rejections to the components in a crude mixture. The process performance, defined as concentration factor (CF ), purification factor (PF ) and recovery yield (REC), is analyzed by computer simulations. The results show that CF and REC increase, but PF decreases with the membrane rejection. It is likely that optimum operating conditions exist to give the best process performance because the increases in eluant and affinity-recycle flow rate improve REC but decrease PF.
文摘Single step and multi step CARE processes are optimized by computer simulations based on the mathematical model proposed previously. The product of purification factor and recovery yield is used as the objective function for optimizing a single step process. The objective function for the optimization of a multi step process is considered to obtain an anticipated product purity at a maximum recovery yield and a minimum number of CARE inividuals. Pairs of the operating conditions (eluant and affinity recycle flow rates) exist to give the maximums of above objective functions when membrane rejections to ligates and contaminants are equal in value. The optimum affinity recycle flow rate decreases with the increase of membrane rejections and equilibrium binding fractions of ligates. For a multi step process, when contaminants are rejected less than ligate, only one pair of the optimum eluant and affinity recycle flow rates exists.
基金Project(51472211)supported by the National Natural Science Foundation of ChinaProject(2012CK1006)supported by Scientific and Technical Achievement Transformation Fund of Hunan Province,China
文摘NaxCoO2 is a commonly used cathode material for sodium ion batteries because of its easy synthesis, high reversible capacity and good cyclability. The structural and electrochemical properties of NaxCoO2 during sodium ion insertion/extraction process are studied based on first principles calculations. The calculation results of crystal structure parameters and average intercalation voltage are in good agreement with experiment data. Through calculation of the geometric structure and charge transfer in charging and discharging processes of NaxCoO2, it is found that the oxygen atom surrounding Co of the CoO6 octahedral screens the coulomb potential produced by sodium vacancy in NaxCoO2, and the charge is removed from the entire Co-O layer instead of the Co atom adjacent to sodium vacancy when sodium ions are extracted from the Na CoO2 lattice. Thus, during the insertion/extraction of sodium ion from Na CoO2, the CoO6 octahedral structure undergoes small lattice distortion, which makes the local structure quite stable and is beneficial to the cycling stability of the material for the application of sodium ion batteries.
