ISSN:
1573-0662
Keywords:
nitrate radical
;
solubility
;
sticking coefficient
;
redox potential
;
heterogeneous removal
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Geosciences
Notes:
Abstract The exchange of NO3 radicals with the aqueous-phase was investigated at room temperature (293 K) in a series of wetted denuders. From these experiments, the uptake coefficient of NO3 was determined on 0.1 M NaCl solutions and was found to be γ(NO3) ≥ 2 × 10-3 in good agreement with recent studies. The Henry coefficient of NO3 was estimated to be KH(NO3) = 1.8 M · atm-1, with a (2σ) uncertainty of ±3 M · atm-1. From the upper limit for the Henry coefficient (KH = 5 M · atm-1) and available thermodynamic data, the redox potential of dissolved NO3/NO 3 − is estimated to be in the range of 2.3 to 2.5 V. This range is at the lower boundary of earlier estimates. The results are discussed in the light of a recent publication. Based on our data and a model of the transport and chemistry in the liquid film, an upper limit is derived for the product of the Henry coefficient KH and the rate coefficient k 10 of the potential reaction NO3 + H2O → HNO3 + OH. For KH = 0.6 M · atm-1, we find k 10 〈 0.05 s-1 · atm-1, i.e., about 100 times smaller than what was suggested by Rudich and co-workers. Because of its small solubility, heterogeneous removal of NO3 is only important under conditions where the dissolved NO3 is removed quickly from equilibrium, for example by reactions with Cl− or HSO 3 − ions in the liquid-phase. Otherwise, heterogenous removal should mainly proceed via N2O5.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1005860312363
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