Journal of Atmospheric Chemistry

, Volume 61, Issue 1, pp 31–55

Kinetics of ammonia and ammonium ion inhibition of the atmospheric oxidation of aqueous sulfur dioxide by oxygen

  • Punit Kumar Mudgal
  • Anil Kumar Sharma
  • C. D. Mishra
  • S. P. Bansal
  • K. S. Gupta
Article

DOI: 10.1007/s10874-009-9123-8

Cite this article as:
Mudgal, P.K., Sharma, A.K., Mishra, C.D. et al. J Atmos Chem (2008) 61: 31. doi:10.1007/s10874-009-9123-8

Abstract

This is the first study, which shows both NH3 and NH4+ to inhibit the autoxidation of aqueous SO2 in the pH range 7.0–8.5. The rate of the autoxidation, Raut, in both buffered and unbuffered media at a fixed pH is in conformity with the rate law:
$$ R_{aut} ={{R_0 } \mathord{\left/ {\vphantom {{R_0 } {\left( {{\text{1 + }}B\left[ {\text{Inh}} \right]_{\text{T}} } \right)}}} \right. } {\left( {{\text{1 + }}B\left[ {\text{Inh}} \right]_{\text{T}} } \right)}} $$
where R0 is rate in the absence of the inhibitors, B is a pH dependent empirical constant and [Inh]T is the analytical concentration of NH3 or NH4+. Both ammonia and ammonium ions appear to inhibit the autoxidation either by scavenging SO4 radicals or by forming less-reactive /unreactive Co(II)-NH3 complexes or both. The atmospheric relevance of the inhibition by ammonia and ammonium ions is discussed.

Keywords

AmmoniaAmmonium ionSulfur(IV)Metal ionsAutoxidationInhibitionKinetics

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  • Punit Kumar Mudgal
    • 1
  • Anil Kumar Sharma
    • 1
  • C. D. Mishra
    • 1
  • S. P. Bansal
    • 1
  • K. S. Gupta
    • 1
  1. 1.Atmospheric Chemistry Lab, Department of ChemistryUniversity of RajasthanJaipurIndia