Secondary aerosol formation from atmospheric reactions of aliphatic amines

Abstract

Abstract. Although aliphatic amines have been detected in both urban and rural atmospheric aerosols, little is known about the chemistry leading to particle formation or the potential aerosol yields from reactions of gas-phase amines. We present here the first systematic study of aerosol formation from the atmospheric reactions of amines. Based on laboratory chamber experiments and theoretical calculations, we evaluate aerosol formation from reaction of OH, ozone, and nitric acid with trimethylamine, methylamine, triethylamine, diethylamine, ethylamine, and ethanolamine. Entropies of formation for alkylammonium nitrate salts are estimated by molecular dynamics calculations enabling us to estimate equilibrium constants for the reactions of amines with nitric acid. Though subject to significant uncertainty, the calculated dissociation equilibrium constant for diethylammonium nitrate is found to be sufficiently small to allow for its atmospheric formation, even in the presence of ammonia which competes for available nitric acid. Experimental chamber studies indicate that the dissociation equilibrium constant for triethylammonium nitrate is of the same order of magnitude as that for ammonium nitrate. All amines studied form aerosol when photooxidized in the presence of NOx with the majority of the aerosol mass present at the peak of aerosol growth consisting of aminium (R3NH+) nitrate salts, which repartition back to the gas phase as the parent amine is consumed. Only the two tertiary amines studied, trimethylamine and triethylamine, are found to form significant non-salt organic aerosol when oxidized by OH or ozone; calculated organic mass yields for the experiments conducted are similar for ozonolysis (15% and 5% respectively) and photooxidation (23% and 8% respectively). The non-salt organic aerosol formed appears to be more stable than the nitrate salts and does not quickly repartition back to the gas phase.

Enhanced trimethylamine-containing particles during fog events detected by single particle aerosol mass spectrometry in urban Guangzhou, China

“…Besides, TMA can also participate in the formation of secondary organic aerosol. Several studies have shown that gas-phase TMA could form non-salt organic aerosol products through reaction with oxidizing agents such as O 3 , OH, and NO 3 radical (Murphy et al, 2007;Silva et al, 2008). The relative importance of atmospheric behaviors of TMA in different regions is not yet clear.…”

“…Tan et al (2002) suggested that the presence of the TMA within aqueous surface on particles would promote the accumulation of sulfate and nitrate (R2 and R3). TMA also has the potential to undergo gas phase acidebase reactions (R4) with gaseous acids (e.g., HCl, HNO 3 and H 2 SO 4 ) mimic ammonia to form inorganic salts (Angelino et al, 2001;Murphy et al, 2007). Additionally, heterogeneous reaction between gas-phase TMA and acid (R5) could take place as well.…”

“…TMA can react with gas phase acid (e.g., sulfuric acid and nitric acid) in the atmosphere to form particulate salts through acidebase reactions (Kurtén et al, 2008;Murphy et al, 2007;Silva et al, 2008), and it is even more important than ammonia in enhancing atmospheric nucleation (Erupe et al, 2011;Kurtén et al, 2008;Smith et al, 2010). Through laboratory experiments and ambient observations using an aerosol time-of-flight mass spectrometer (ATOFMS), Rehbein et al (2011) demonstrated that cloud/fog processing could enhance gas-to-particle partitioning of TMA, which is highly dependent on aerosol water content, and that TMA prefers to accumulate in acidic particles.…”

Ozonolysis of Trimethylamine Exchanged with Typical Ammonium Salts in the Particle Phase

“…12 Amines observed in Marshall Field Site, Colorado (2007), 13 North Boulder, Colorado (2009), and Atlanta, Georgia (2009) 14 have also been confirmed to play the same role in NPF events. 12 In laboratory studies, NPF was observed when amines were added into a smog chamber or flow tube reactor containing a certain concentration of nitric acid, 15 sulfuric acid, 16 or methanesulfonic acid (MSA). 17,18 Density functional theory (DFT) calculations indicated that amine molecules act as cluster stabilizers for nucleation precursors, 19,20 and therefore promote nuclei formation.…”

“…34 It has also been found that significant nonsalt organics contributed to the secondary organic aerosol (SOA) from ozone oxidation and photooxidation of TMA and TEA. 15 Particulate amines and secondary oxidation products from amines in the particle phase are associated with adverse aerosol health impacts. For example, concentrations of 20 mL·m −3 trimethylamine were found to found to irritate the mucous membranes and eyes.…”