Ken99
- 1
- 0
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!
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!