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Published March 21, 2011 | Published
Journal Article Open

Conversion of gaseous nitrogen dioxide to nitrate and nitrite on aqueous surfactants


The hydrolytic disproportionation of gaseous NO2 on water's surface (2 NO_2 + H_2O → HONO + NO_3- + H+) (R1) has long been deemed to play a key, albeit unquantifiable role in tropospheric chemistry. We recently found that (R1) is dramatically accelerated by anions in experiments performed on aqueous microjets monitored by online electrospray mass spectrometry. This finding let us rationalize unresolved discrepancies among previous laboratory results and suggested that under realistic environmental conditions (R1) should be affected by everpresent surfactants. Herein, we report that NO_2(g) uptake is significantly enhanced by cationic surfactants, weakly inhibited by fulvic acid (FA, a natural polycarboxylic acid) and anionic surfactants, and unaffected by 1-octanol. Surfactants appear to modulate interfacial anion coverage via electrostatic interactions with charged headgroups. We show that (R1) should be the dominant mechanism for the heterogeneous conversion of NO_2(g) to HONO under typical atmospheric conditions throughout the day. The photoinduced reduction of NO_2 into HONO on airborne soot might play a limited role during daytime.

Additional Information

© 2011 the Owner Societies. Received 13th August 2010, Accepted 7th January 2011. S. E. appreciates the Japan Society for the Promotion of Sciences Postdoctoral Fellowships for Research Abroad. This work was supported by National Science Foundation Grant ATM-0714329.

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Published - Kinugawa2011p13074Physical_Chemistry_Chemical_Physics.pdf


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