Computational study on atmospheric transformationmechanisms and kinetics of volatile amines

Ambient atmosphere contains large amounts of volatile organic compounds (VOCs). They have both anthropogenic and biogenic sources. In general, natural sources dominate over anthropogenic sources on a global scale. However, anthropogenic emissions play an important role in urbanized areas. VOCs released into the atmosphere can undergo various atmospheric transformation. Previous studies indicated that the atmospheric transformation of VOCs can contribute to the formation of O₃ and secondary organic aerosol (SOA), which can influence the regional air quality and the global climate. Therefore, detailed atmospheric transformation mechanisms and kinetics of VOCs are indispensable to quantify the regional or global impacts of VOCs chemistry. Amines are an important kind of VOCs, and are emitted from a variety of natural and anthropogenic sources including animal husbandry, biomass burning, motor vehicles, cooking, fish processing, sewage treatment, waste incineration, vegetation, soil and ocean, etc. In addition, CO₂ capture unit in a promising amines-based post-combustion CO₂ capture (PCCC) technology has become an important source of anthropogenic amines in the atmosphere. Besides, it has been found that amines solvents can be degraded in the capture units, and the solvents degradation can take as much as 10% of total cost of CO₂ capture. The degradation products of amines in the capture units include some low molecular weight amines (such as methylamine, dimethylamine, trimethylamine), ammonia, amides, nitrosamines, aldehydes, and other species. Therefore, with the large-scale application of amines-based PCCC technology, the types and concentrations of amines in the atmosphere will be increased. In recent years, more and more attentions have been paid to the atmospheric transformation mechanisms and kinetics of amines emitted from PCCC units. Based on the previous review of the atmospheric transformation of amines, this review summarized the latest results from computational studies on the atmospheric transformation mechanisms and kinetics of amines emitted from PCCC units published after the year 2012. The two kinds of atmospheric transformation pathways (oxidation reactions and participation in the new particle formation) of CO₂ capture related amines were summarized in this review. Finally, an outlook for atmospheric transformation of amines was proposed. This could be helpful to understand the fate of amines from PCCC units and its impacts on human health and the environment.