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:
- Nitric acid can condense on nanoparticles with amines at a comparable
or higher temperature than with ammonia
- Amines with additional hydrogen bonding ability can condense with
nitric acid at room temperature
- Particles condensed with amines and nitric acid may absorb water at
low relative humidity to influence their subsequent atmospheric aging
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.