The Experts below are selected from a list of 15 Experts worldwide ranked by ideXlab platform
Yoshinobu Tanaka - One of the best experts on this subject based on the ideXlab platform.
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Ion-exchange membrane electrodialysis program and its application to multi-stage continuous saline water desalination
Desalination, 2012Co-Authors: Yoshinobu TanakaAbstract:Abstract The first part of this article describes the program of a one-stage continuous electrodialysis process operating at a constant current mode. The full continuous electrodialysis program is developed and explained definitely by arranging equations systematically with the following supplementary steps. For preventing scale formation in Concentrating Cells, salt solutions supplied to the desalting Cells are also fed to the Concentrating Cells. Influence of temperature to the performance of the electrodialyzer is taken into account. Pressure drop in the electrodialyzer is evaluated by incorporating the functions of hydrodynamic diameters of desalting and Concentrating Cells and slots. An electric current screening effect of a spacer is determined by the volume ratio of spacer rods in a desalting and Concentrating Cell. In the second part of this article, saline water is desalinated with the multi-stage electrodialysis program by operating the process at a constant concentration mode. Changing salt concentration of a feeding solution in each stage incrementally, the performances of the electrodialyzer such as; ion and solution flux across a membrane pair; Cell voltage; current density; salt concentration in Concentrating Cells; energy consumption; water recovery; limiting current density; pressure drop in the Cells and slots are computed in each stage. Energy consumption, water recovery, pressure drop and membrane area are computed in the total stages to produce drinking water.
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Pressure distribution, hydrodynamics, mass transport and solution leakage in an ion-exchange membrane electrodialyzer
Journal of Membrane Science, 2004Co-Authors: Yoshinobu TanakaAbstract:The static solution head in an entrance desalting duct Hen, that in an exit desalting duct Hex and their difference ΔH were measured by electrodialysis of seawater using a practical scale electrodialyzer. Applying hydrodynamics to this electrodialysis system on the basis of the assumption that the flow pattern in a desalting Cell is laminar flow, which was demonstrated from the relationship between the Reynolds number and the static head drop in a desalting Cell, we evaluated: (1) the static head difference between an entrance and an exit of a current-passing section ΔHc and that of a passageway ΔHw; (2) the spacer friction factor fs expressing the effect of a spacer to friction resistance; (3) the distribution coefficient of solutions flowing into every desalting Cell θ; (4) the static head Hs, velocity head Hv and friction head Hf of a solution flowing through a duct; (5) the velocity head of solutions flowing into or out of current-passing sections through passageways Hv,w. The solution flow in a stack is classified as a one-way flow system, in which the flow direction in an entrance duct is identical with that in an exit duct, or a two-way flow system, in which the flow direction in an entrance duct and that in an exit duct are opposite to each other. In order to operate an electrodialyzer stably by maintaining a uniform ΔH in a stack, it is preferable to adopt one-way flow system rather than two-way flow system, and further it is desirable to decrease the difference of Hv,w between the values in an entrance passageway and an exit passageway, (Hv,w)en−(Hv,w)ex. Solution leakage was evaluated by means of seawater electrodialysis based on the extended overall mass transport equation in which the volume flux is expressed by the terms of electro-osmosis, concentration-osmosis and leakage of solutions. The overall mass transport equation was introduced from the non-equilibrium thermodynamics. We found that the solution leakage moving from a desalting Cell to a Concentrating Cell and that moving from a Concentrating Cell to a desalting Cell arise at the same time in the electrodialyzer. These phenomena are attributed to the fact that the pressure in a desalting Cell becomes larger than that in a Concentrating Cell in some part, and that in a desalting Cell becomes smaller than that in a Concentrating Cell in another part. These events arise because the distribution of solution velocity and friction head is not uniform in desalting Cells.
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mass transport and energy consumption in ion exchange membrane electrodialysis of seawater
Journal of Membrane Science, 2003Co-Authors: Yoshinobu TanakaAbstract:Abstract The theory of ionic transport processes in ion-exchange membrane electrodialysis system was developed. The fundamentals in this theory is expressed by the overall mass transport equation of ions and a solution across a membrane pair. The equation includes overall transport number λ , overall diffusion coefficient μ , overall electro-osmotic coefficient φ and overall osmotic coefficient ρ . These parameters indicate the characteristics of an ion-exchange membrane pair placed in an electrolyte solution containing more than two kinds of ions. These parameters were measured by the electrodialysis of seawater. Parameters λ , μ and φ were expressed by empirical functions of ρ . These functions facilitate the simulation of the electrodialytic process. Parameter ρ was found to have the relation to non-equilibrium parameter; filtration coefficient L p . The formulas were obtained in order to express various aspects such as the transport of ions and solutions across membranes, electrolyte concentration in both a desalting and Concentrating Cell, desalting ratio of a desalted solution and current efficiency. Ionic constituents in a concentrated solution were also measured by the seawater electrodialysis. The relationship between current density and the equivalent ratio of ions in a concentrated solution was expressed by empirical formulas. Thereby, the concentration of Na + , K + , Mg 2+ , Ca 2+ , Cl − and SO 4 2− ions in a concentrated solution was estimated. The voltage applied to a Cell pair is known to be related to electrical resistance and membrane potential. The electrical resistance of solutions in a Cell pair was determined by the specific resistance measurement of electrolyte solutions. The direct current electrical resistance of membranes in a Cell pair was measured by the seawater electrodialysis. The effect of concentration polarization on the voltage applied to a Cell pair is seen in the direct current resistance of the membrane. Energy consumption during the process of seawater electrodialysis was evaluated using the function of the voltage applied to a Cell pair. The energy consumption, the limiting current density and the saturation current density are discussed on the basis that the current density and solution velocity (electrolyte concentration) in desalting Cells are distributed in an electrodialyzer.
Xiaofu Guo - One of the best experts on this subject based on the ideXlab platform.
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Concentrating brine from seawater desalination process by nanofiltration electrodialysis integrated membrane technology
Desalination, 2016Co-Authors: Jie Liu, Junsheng Yuan, Bingjun Wang, Yachao Hao, Xiaofu GuoAbstract:Abstract Extraction and Concentrating of NaCl from brine were promising technologies to solve the disposition problem of seawater desalination. A novel nanofiltration–electrodialysis (NF–ED) integrated membrane technology was proposed and investigated. The separation of monovalent & bivalent ions and Concentrating of solute were realized in NF and ED process, respectively. A kind of NF membrane with high SO42 − rejection and common homogeneous ion exchange membrane were investigated. The results showed that the operating pressure and feeding solution concentration have obvious effect on the water permeate flux and ions rejection ratios. Due to the special properties of NF membrane, almost all of the SO42 − in the brine was rejected. The rejection of Ca2 + and Mg2 + was 40% and 87%. The concentrations of Ca2 + in permeate were 392 mg/L in a brine-recycle experiment, which induce lower scaling potential when used as the raw water of ED. The highest NaCl concentration in the Concentrating Cell could be as high as 160 g/L and the NaCl recovery was about 70% after 5 h under 15 V, while total concentration of “impure ions” (K+, Ca2 + and Mg2 +) was about 5 g/L. A concept process was also proposed attempting to realize comprehensive utilization of brine.
Jie Liu - One of the best experts on this subject based on the ideXlab platform.
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Concentrating brine from seawater desalination process by nanofiltration electrodialysis integrated membrane technology
Desalination, 2016Co-Authors: Jie Liu, Junsheng Yuan, Bingjun Wang, Yachao Hao, Xiaofu GuoAbstract:Abstract Extraction and Concentrating of NaCl from brine were promising technologies to solve the disposition problem of seawater desalination. A novel nanofiltration–electrodialysis (NF–ED) integrated membrane technology was proposed and investigated. The separation of monovalent & bivalent ions and Concentrating of solute were realized in NF and ED process, respectively. A kind of NF membrane with high SO42 − rejection and common homogeneous ion exchange membrane were investigated. The results showed that the operating pressure and feeding solution concentration have obvious effect on the water permeate flux and ions rejection ratios. Due to the special properties of NF membrane, almost all of the SO42 − in the brine was rejected. The rejection of Ca2 + and Mg2 + was 40% and 87%. The concentrations of Ca2 + in permeate were 392 mg/L in a brine-recycle experiment, which induce lower scaling potential when used as the raw water of ED. The highest NaCl concentration in the Concentrating Cell could be as high as 160 g/L and the NaCl recovery was about 70% after 5 h under 15 V, while total concentration of “impure ions” (K+, Ca2 + and Mg2 +) was about 5 g/L. A concept process was also proposed attempting to realize comprehensive utilization of brine.
Junsheng Yuan - One of the best experts on this subject based on the ideXlab platform.
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Concentrating brine from seawater desalination process by nanofiltration electrodialysis integrated membrane technology
Desalination, 2016Co-Authors: Jie Liu, Junsheng Yuan, Bingjun Wang, Yachao Hao, Xiaofu GuoAbstract:Abstract Extraction and Concentrating of NaCl from brine were promising technologies to solve the disposition problem of seawater desalination. A novel nanofiltration–electrodialysis (NF–ED) integrated membrane technology was proposed and investigated. The separation of monovalent & bivalent ions and Concentrating of solute were realized in NF and ED process, respectively. A kind of NF membrane with high SO42 − rejection and common homogeneous ion exchange membrane were investigated. The results showed that the operating pressure and feeding solution concentration have obvious effect on the water permeate flux and ions rejection ratios. Due to the special properties of NF membrane, almost all of the SO42 − in the brine was rejected. The rejection of Ca2 + and Mg2 + was 40% and 87%. The concentrations of Ca2 + in permeate were 392 mg/L in a brine-recycle experiment, which induce lower scaling potential when used as the raw water of ED. The highest NaCl concentration in the Concentrating Cell could be as high as 160 g/L and the NaCl recovery was about 70% after 5 h under 15 V, while total concentration of “impure ions” (K+, Ca2 + and Mg2 +) was about 5 g/L. A concept process was also proposed attempting to realize comprehensive utilization of brine.
Bingjun Wang - One of the best experts on this subject based on the ideXlab platform.
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Concentrating brine from seawater desalination process by nanofiltration electrodialysis integrated membrane technology
Desalination, 2016Co-Authors: Jie Liu, Junsheng Yuan, Bingjun Wang, Yachao Hao, Xiaofu GuoAbstract:Abstract Extraction and Concentrating of NaCl from brine were promising technologies to solve the disposition problem of seawater desalination. A novel nanofiltration–electrodialysis (NF–ED) integrated membrane technology was proposed and investigated. The separation of monovalent & bivalent ions and Concentrating of solute were realized in NF and ED process, respectively. A kind of NF membrane with high SO42 − rejection and common homogeneous ion exchange membrane were investigated. The results showed that the operating pressure and feeding solution concentration have obvious effect on the water permeate flux and ions rejection ratios. Due to the special properties of NF membrane, almost all of the SO42 − in the brine was rejected. The rejection of Ca2 + and Mg2 + was 40% and 87%. The concentrations of Ca2 + in permeate were 392 mg/L in a brine-recycle experiment, which induce lower scaling potential when used as the raw water of ED. The highest NaCl concentration in the Concentrating Cell could be as high as 160 g/L and the NaCl recovery was about 70% after 5 h under 15 V, while total concentration of “impure ions” (K+, Ca2 + and Mg2 +) was about 5 g/L. A concept process was also proposed attempting to realize comprehensive utilization of brine.