I am bit confused. I am calculating the CO2 sequestration potential of using CO2 as a neutralizing agent of alkaline wastewater instead of a common acid. In my opinion, as long as the pH of the following water bodies does not drop below 8, which is for example the average pH of the north sea, the initially absorbed CO2 during the wastewater neutralization should remain in the liquid phase as bicarbonate. As the neutralization occurs in equilibrium with the surrounding atmosphere, I don't expect a subsequent degassing and shift of the equilibrium towards gaseous CO2?
In my opinion, it would be differently if the neutralization occurs under a closed atmosphere with high CO2 level. After release of the wastewater to the sewer network, a portion of the CO2 would be stripped from the aqueous phase and released to the atmosphere. Temperature effects can be ignored for now.
Any different thoughts? Did I omit something?
I'm not a chemist, but I recall CO2 can also form carboxylic acid, which is why it can be used to treat alkaline waters. I don't know the stability of this in water at various pHs/temps, but I'm sure the info is out there somewhere.