Potential Enhancement in Atmospheric New Particle Formation by Amine-Assisted Nitric Acid Condensation at Room Temperature
Kuanfu Chen1, Kai Zhang1,2 and Chong Qiu3
Affiliations:
1 Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan, Jiangsu 215300, China
2 Data Science Research Center (DSRC), Duke Kunshan University, Kunshan, Jiangsu 215300, China
3 Department of Chemistry and Chemical & Biomedical Engineering, University of New Haven, West Haven, Connecticut 06516, USA
Corresponding author: CHONG QIU (CQIU@newhaven.edu)
Key points:
Abstract
Atmospheric aerosol contributes significantly to public health and plays a critical role in global climate. Recent laboratory experiments showed that new particle formation is significantly enhanced by rapid condensation of nitric acid and ammonia at low temperatures. Amines are derivatives of ammonia with a significant presence in the atmosphere. Using thermodynamic simulations, the condensation of amines and nitric acid under various temperatures was systematically evaluated. Monoamines condense with nitric acid at a temperature comparable to ammonia, while amines with additional hydrogen bonds (such as monoethanolamine and piperazine) condense with nitric acid at room temperature. The condensed amines and nitric acid also lower the aerosol deliquescence point, which may alter its subsequent atmospheric transformations. Our results suggest the potentially critical role of amines in new particle formation via condensation with nitric acid to rapidly grow newly formed clusters over their critical size in a wide temperature range.
Plain Language Summary
The collection of microscopic liquid and solid nanoparticles suspended in the air is commonly referred as aerosol or particulate matters. It is important for us to understand how these nanoparticles are formed and grow in the atmosphere, because aerosol plays critical roles in public health and the global climate. Ammonia and amines are air pollutants emitted into the air in large quantities. Recently, ammonia and nitric acid are found to facilitate the grow of newly formed aerosol particles at low temperature. Due to the similarities between ammonia and amines, amines and nitric acid may also assist in the growth of ambient nanoparticles. Our hypothesis was evaluated using thermodynamic simulations on a mixture of ammonia, amines, nitric acid and sulfuric acid under various temperature and relative humidity conditions. Similar to ammonia, simple amines may enhance particle growth at low temperature with nitric acid. Notably, nitric acid and amines with the ability to form additional hydrogen bonds may facilitate particle growth at room temperature. The resulting aerosol may absorb water even at low relative humidity, leading to distinctively different particle properties and climate effects. Our results indicate that amines and nitric acid could contribute significantly to ambient particle growth at various temperatures.