Electrodialysis with different anions

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The discussion centers on the electrodialysis process involving sodium chloride and sodium hydroxide solutions, focusing on predicting chloride ion movement under varying concentrations and voltages. The application of a 10V-30V potential difference allows both Cl- and OH- ions to migrate through a membrane, while Na+ ions enter from the opposite side. Observations indicate that the pH in the right compartment remains stable, suggesting a consistent influx of OH- ions. The impact of OH- concentration in the left compartment on the electrodialysis process is questioned, with references to models like the Nernst-Planck and Poisson-Nernst-Planck equations for analyzing ion diffusivity. Membrane permeability is highlighted as a crucial factor affecting ion movement, varying by ion type and membrane characteristics.
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An electrodialysis cell has the left compartment containing sodium chloride solution; its right compartment contains sodium hydroxide solution. The concentrations of both solutions are 0.5 mol/L. There is a membrane separating two compartments and only allow charged ions pass through. An electric potential difference (10V-30V) is applied between these two compartments through embedded electrodes.
Under such a potential difference, both anions Cl- and OH- ions in the left compartment are pushed through the membrane; while Na+ enters from the opposite direction. My question is how to predict the amount of chloride ions through under different original concentrations (NaCl and NaOH) and under different voltages. I did some test and found the pH level in the right compartment remains almost the same, indicating OH- ions constantly enter the right compartment and compensate for its loss during oxidation reaction. What I am not clear is how the OH- concentration in the left compartment will affect the electrodialysis processes and how to quantify this effect.
I read some literatures about the single species model like the Nernst-Planck equation but it seems to consider the overall anion diffusivity only. A Poisson-Nernst-Planck (PNP) can consider multiple species. I read someone used it to predict the transient chloride diffusivity based on the ratio between the catholyte and anolyte. Is there any good way or analytical model which may be used to qualitatively or quantitative assess the electrodialysis rate?
Thank you very much!
 
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My guess is that the most important parameter will be membrane permeability. Not only it will be different for each ion, but it will be also different for different membranes.
 
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