pH of demineralized water
pH of demineralized water
(OP)
The pH of water entering the demineralising chain is 7.02. The pH of this after passing through the cationic drum is 4. The pH of water leaving the anionic drum to the storage tank is 10.4. I would like to know if the pH of this demineralised water is normal to be 10.4. I understand there is escape of OH from the anionic drum but is this escape linked in anyway with the performance of the Resin?
Can the pH of the demineralised water be below 8?
Can the pH of the demineralised water be below 8?





RE: pH of demineralized water
You are correct in your thinking. The pH of demineralized water should be approximately 10. The elevatd pH is because the leakage of ions leaving the demineralizer will be in the form of NaOH. Na from the cation unit and OH from the anion unit. The OH will cause the elevated pH.
The pH of demineralized water is somewhat pointless because there is no buffering capacity inherent with low mineral water. A slight amount of chemical is capable of changing the pH.
RE: pH of demineralized water
RE: pH of demineralized water
Some power plants use nitrogen blanketing to prevent the demineralized water from absorbing oxygen. Vacuum degasification is also used.
CO2 is also absorbed from the air causing the demineralized water pH to drop.
What is the objection to morpholine?
RE: pH of demineralized water
Also I would like to know if the rate at which OH escapes from the anionic drum can be related in monitoring the life cycle of the resin.
RE: pH of demineralized water
http://www.lenntech.com/boiler/corrosion.htm
ht
You probably can not stop use of the mopholine.
Cations and anions in water must balance. The Na leaks from the cation. In order to maintain the ionic water balance, the OH is then pulled from the anion. To reduce the concentration of OH, you have to decrease the Na leakage from the cation.
RE: pH of demineralized water
Gary Schreiber, CWS VI
The Purolite Co.
RE: pH of demineralized water
Thanks Doug
RE: pH of demineralized water
The raw source will not have much effect on the effluent pH of the demineralizer.
Cation leakage is important because it effects the purity of the effluent. A strong base anion exchanger can remove only the acidity, not the sodium. A strong base anion exchanger converts the sodium salts to sodium hydroxide by salt splitting, which then creates high conductivity and pH value in the effluent.
If you have a pH less than 8, then there is something going wrong in your demineralizer.
The morphonline that is being added has nothing to do with the demineralizer. One would assume that the morphonline has to do with a power plant downstream of the demineralizer.