Kinetics and Products of the Aqueous Phase Oxidation of Triethylamine by OH

Low-molecular-weight alkyl amines have attracted attention for their roleinnew particle formation ultrafine Particle growth, and neutralizing; aerosol acidity. The major source of the low-molecular-weight aminium ions in fine particles is generally believed to be the corresponding gaseous precursors emitted to the atmosphere. Relatively little work has investigated whether larger amines can be transformed into smaller amines within the condensed phase itself In this work, we studied the bulk aqueous phase oxidation kinetics andproduc.ts of triethylamine/triethylaminiunl (pKa = 10.75) against OH under different values of pH. Using relative rate kinetics, we find that the oxidation rates against OH for TEA and TEAR are (74.3 6.5) >9 108 and (1.8 + 0.2) x 108 M-1 s-1, respectively. Ina. dilute NaHSO4 solution with a pH of 3.2, the ionic products of TEAR' oxidation include diethylaminium, ethylaminium, and ammonium ions, which are formed within an atmospherically relevant oxidation time scale. Under common atmospheric oxidationconditions,aqueous phase is calculated to be competitive with gas phase oxidation as a sink for TEA. This indicates that some low-molecular-weight aminium ions can also be the products of she aqueous phase oxidation of larger N-containing molecules.