Determining the Henry's volatility coefficient of nitrosamines in CO₂ capture solvents

Fundamental properties of nitrosamines, such as their Henry's law constants, are needed to accurately predict the gas-phase partitioning and mitigate emissions of these volatile compounds from operating CO₂ capture systems. In this work, the Henry's volatility coefficient of several environmentally relevant nitrosamines were experimentally obtained from water, from a concentrated amine solution and from a CO₂ loaded amine solution using a static headspace solid phase microextraction and gas chromatography mass spectrometry method. The dimensionless Henry's volatility coefficients of N-nitrosodimethylamine and N-nitrosodiethylamine were found to be range of 0.001–0.1 at CO₂ absorber exit temperatures from 25 to 55 °C. A linear temperature dependency of the Henry's volatility coefficient for these nitrosamines was observed. CO₂ loading in the amine solvent increases the Henry's volatility coefficient of the more non-polar nitrosamine while it decreased the Henry's volatility coefficient of the more polar nitrosamine. Similar to parent amines, the polarity of the individual nitrosamines plays a key role in its Henry's volatility coefficients and gas phase partitioning from concentrated amine solutions.