Atmospheric Fate of Monoethanolamine: Enhancing New Particle Formation of Sulfuric Acid as an Important Removal Process

摘要

Monoethanolamine (MEA), a potential atmospheric pollutant from the capture unit of a leading CO_2 capture technology, could be removed by participating H2S04-based new particle formation (NPF) as simple amines. Here we evaluated the enhancing potential of MEA on H2S04-based NPF by examining the formation of molecular clusters of MEA and H2S04 using combined quantum chemistry calculations and kinetics modeling. The results indicate that MEA at the parts per trillion (ppt) level can enhance HjS04-based NPF. The enhancing potential of MEA is less than that of dimethylamine (DMA), one of the strongest enhancing agents, and much greater than methylamine (MA), in contrast to the order suggested solely by their basicity (MEA < MA < DMA). The unexpectedly high enhancing potential is attributed to the role of -OH of MEA in increasing cluster binding free energies by acting as both a hydrogen bond donor and acceptor. After the initial formation of one H2S04 and one MEA cluster, the cluster growth mainly proceeds by first adding one ^SO^ and then one MEA, which differs from growth pathways in H2S04-DMA and H2S04-MA systems. Importantly, the effective removal rate of MEA due to participation in NPF is comparable to that of oxidation by hydroxyl radicals at 278.1S K, indicating NPF as an important sink for MEA.