The effect of carbonate ions in brine on electrolysis
Thread Content
This post was last edited by sunjl1981 on 2013-1-6 at 20:15. I have recently started working with ion-exchange membrane caustic soda; I’ve read a lot of material on the removal of substances such as calcium, magnesium, and sulfate ions, but nothing regarding the removal of carbonate ions. Is it unnecessary to remove carbonate ions? Those with experience could please give some guidance. # ， ， &
Acid adjustment is carried out before entering the resin tower, and the effect of carbonic acid—namely the formation of carbon dioxide in chlorine—has no impact on the electrolyzer or the membrane.
The high carbonate content consumes more soda ash, with no impact on the electrolyzer or membrane
The effect of carbonate ions in concentrated brine on electrolysis: 1. Increases acid consumption. 2. Affects the concentration of chlorine gas at the outlet. 3. Causes foaming in the anode solution, leading to an increase in gas pockets in the anode chamber and thus an increase in resistance and voltage. 4. Hinders flow in the upper part of the anode solution, making it easy for the membrane at the top to crack. 5. Prone to causing local pressure fluctuations. 6. Generates bubbles that affect the distribution of the electrolyte. 7. Generates bubbles that affect the concentration of the electrolyte
It should have little impact; production at our factory has continued as usual, and everything is operating well.
Our secondary brine is not pH-adjusted with acid; however, carbonate ions can affect the purity of chlorine and also increase the amount of acid that needs to be added to the electrolyzer. Therefore, as long as the calcium and magnesium levels in the brine are satisfactory, efforts should be made to reduce the amount of soda ash added; this not only helps to lower consumption but also improves the purity of chlorine and reduces acid consumption
The carbonate ions in the brine should have no effect on electrolysis. In our factory, which has been producing ion-exchange membrane caustic soda for many years, we have never heard of carbonate ions having any impact on electrolysis. Acid is added to the brine before it enters the electrolyzer to adjust the pH to 2-3; this process results in the formation of H2CO3, and when heated, some CO2 is produced, thereby consuming a small amount of acid. After entering the electrolyzer, chlorine is generated, and when chlorine reacts with water, HCl is produced, which in turn leads to further formation of H2CO3. The CO2 produced decomposes and ends up in the chlorine system, affecting the purity of the chlorine.
When acidic brine is introduced into the tank, carbon dioxide has generally been removed; however, alkaline brine from diaphragm cells can affect the purity of chlorine.