Heterogeneous Chemistry of Alkylamines with Sulfuric Acid: Implications for Atmospheric Formation of Alkylaminium Sulfates

Abstract

The heterogeneous interaction of alkylamines with sulfuric acid has been investigated to assess the role of amines in aerosol growth through the formation of alkylaminium sulfates. The kinetic experiments were conducted in a low-pressure fast flow reactor coupled to an ion drift-chemical ionization mass spectrometer (ID-CIMS). The measurements of heterogeneous uptake of methylamine, dimethylamine, and trimethylamine were performed in the acidity range of 59-82 wt % H(2)SO(4) and between 243 and 283 K. Irreversible reactive uptakes were observed for all three alkylamines, with comparable uptake coefficients (gamma) in the range of 2.0 x 10(-2) to 4.4 x 10(-2). The measured gamma value was slightly higher in more concentrated sulfuric acid and at lower temperatures. The results imply that the heterogeneous reactions of alkylamines contribute effectively to the growth of atmospheric acidic particles and, hence, secondary organic aerosol formation.

Heterogeneous Uptake of Amines by Citric Acid and Humic Acid

“…Figure 2 increase notably owing to the consumption of available reactive sites. In Figure 1E and F, the QMS signal of TMA comes back to its baseline eventually (40 min), and it does so for all of these amines on humic acid, with different saturation times (19,10, and 1 min for MA, DMA, and TMA, respectively) ( Figure 2). However, the recovery rates of MA and DMA on citric acid are very slow ( Figure 1A-D).…”

“…11,17−19 For example, Murphy et al 19 observed rapid particle nucleation when amines were injected into a chamber containing gaseous nitric acid. The γ of methylamine (MA), dimethylamine (DMA), and trimethylamine (TMA) are in the range of 2.0 × 10 −2 −4.4 × 10 −2 on 59−82 wt % H 2 SO 4 film, 10 and the γ are very close to unity for reactions of amines with sulfuric acid or NH 4 HSO 4 clusters. 11,17 The large uptake coefficients also highlight the important role of acid−base reaction as a source of particulate amines.…”

Water Activities and Osmotic Coefficients of Aqueous Solutions of Five Alkylaminium Sulfates and Their Mixtures with H2SO4at 25oC

“…Major pathways of amine removal from the gas phase include photo-oxidation processes (Nielsen et al 2012), gasparticle partitioning via acid-base reactions (Wang et al 2010;Rehbein et al 2011;Liu et al 2012), and the displacement of ammonia from ammonium salts under elevated amine gas phase concentrations (Lloyd et al 2009;Bzdek et al 2010;Qiu et al 2011;Chan and Chan 2012). The resulting alkyl-ammonium (aminium) salts -including sulfates, nitrates (Pratt et al 2009), and carboxylates (Smith et al 2010) -can promote particle growth and cloud droplet formation.…”

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

“…Additionally, heterogeneous reaction between gas-phase TMA and acid (R5) could take place as well. Uptake coefficients measured by Wang et al (2010c) have suggested that heterogeneous reaction with TMA leads to efficient growth of acidic particles.…”