Modelling gaseous and particulate secondary compounds formation during atmospheric degradation of 2-amino-2-methyl-1-propanol (AMP)

Abstract. The use of amines in carbon capture may contribute to high atmospheric emission. Amines have been shown to contribute significantly to the formation of carcinogenic compounds and aerosols. AMP (2-amino-2-methyl-1-propanol (CH₃)2(CH₂OH)CNH₂) is a benchmark amine in carbon capture solvents, but the mechanisms of its contribution to particle formation are not yet well understood. This study aims to investigate the formation of aminium nitrates in the gas and particle phases. In order to model both the mass and number concentrations of the particles formed, reaction pathways for the formation of extremely low volatile products are proposed, as well as nucleation parameterisation. The model is constrained using an atmospheric chamber experiment, where AMP oxidation products were measured, as well as nitric acid (NA) and AMP in the particulate phase. Considering different molecular clusters of the type NAnAMPm allowed us to introduce low-volatility organic compounds likely to partition into the particulate phase. We present a first method considering the formation of a dimer, NA2AMP2, with low volatility and subject to nucleation parameterization, allowing for accurate reproduction of the evolution of the total number and particle size distribution compared to the experiment. This representation highlights an overestimation of the nitrate mass, emphasizing that the AMP/NA ratio in the clusters may not be equivalent to 1/1. A second method aims to correct this overestimation of nitrate mass by introducing NA1AMP2 clusters, which significantly improve AMP/nitrate partitioning in the particulate phase