US EPA

53972 

Journal Article 

Production and decay of ClNO2 from the reaction of gaseous N2O5 with NaCl solution: bulk and aerosol experiments 

Behnke, W; George, C; Sheer, V; Zetzsch, C 

1997 

Yes 

Journal of Geophysical Research
ISSN: 0148-0227
EISSN: 2156-2202 

102 

D3 

3795-3804 

10.1029/96jd03057 

WOS:A1997WK26600020 

The chemistry of N2O5 on liquid NaCl aerosols or bulk NaCl solutions was studied at 291 K by aerosol smog chamber and wetted-wall flow tube experiments. The uptake of N2O5 on deliquescent aerosol was obtained to be (3.2 ± 0.2) x 10-2 (hr error) from the aerosol experiments. In the wetted-wall flow tube we observed that nirryl chloride (CINO2) is the main product of the reaction at NaCl concentrations larger than approximately 0.5 M and almost the only product at concentrations larger than 1 M. The CINO2 yield does not depend linearly on the NaCl concentration, especially at small sodium chloride concentrations (i.e., smaller than 1 M). It appeared that a simple mechanism where N2O5 undergoes two reaction channels (hydrolysis and reaction with Cl-) is unable to explain the observed concentration dependence of the product yield. We propose that N2O5 dissociates to NO2+ and NO3- (rate constant k1 > 10(4) s-1) mainly. The directly hydrolysis of N2O5 (k3[H2O]) is less than 20% of the total reaction. NO2+ reacts with water to form 2H+ and NO3- (k5) or with Cl- to form CINO2 (k4). Neglecting the influence of ionic strength we evaluate k4/k5 to be 836 ± 32 (1"delta" error). Using the wetted-wall flow tube technique, we studied the uptake of nitryl chloride by aqueous solutions containing NaCl. We observed that the uptake coefficient y decreased from (4.84 ± 0.13) x 10-6 on pure water to (0.27 ± 0.02) x 10-6 on a 4.6 M NaCl solution. The sharp decrease of "gamma" with increasing salt concentrations is evidence of reversible hydrolysis. CINO2 dissociates to Cl- + NO2+ (k6). In the absence of Cl- we evaluate H.k6(1/2) to be 0.44 ± 0.01 mol L-1 atm- s-1/2. Finally, we discuss that atomic Cl from photolysis of CINO2 may play a role in the marine boundary layer at high northern latitudes.