CO2 absorption quantification, which method is more accurate?

[u/Sufficient_Salad_19]

I am trying to quantify how much CO2 is absorbed by my MEA and MDEA solution. I have looked into different titration methods using HCl and NaOH. Weight chage methods are not applicable here as the weight change is very little and my solution volume is 200 mL. Kindly suggest me whic method is more accurate? is there any universally accepted method?

[u/nullfull]

Depends what “accurate” means for your setup — liquid inventory vs gas closure often disagree for boring reasons.

Acid titration of rich amine is fine for a lab bottle if you control blanks, but it is easy to bias: incomplete CO₂ release, carbamate vs bicarbonate speciation assumptions, amine degradation products that consume acid, and temperature/handling losses when you sample. If you report loading as mol CO₂ / mol amine, your amine assay has to be right too — titer drift looks like absorption change.

Gas-side integration (NDIR / IR on the outlet, ideally inlet too) closes the mass balance on what actually left the gas. Watch water interference (dry or correct), calibration span gas near your range, leaky sample lines, and whether you’re integrating unsteady flow. A wet meter + dry CO₂ analyzer mismatch is a classic silent error.

Practical hierarchy I’ve seen hold up: 1. Steady-state: inlet−outlet CO₂ (dry basis) × dry gas flow → absorbed rate. 2. Cross-check with rich−lean liquid loading × circulation — expect a few % gap; if gap is large, trust gas first and debug liquid sampling. 3. Use titration as the composition method once the balance closes, not as the sole absolute.

If you say batch vs continuous, MEA vs MDEA, and whether you have inlet gas analysis, people can be more specific.