Measurement of Henry's law and liquid-phase loss rate constants of peroxypropionic nitric anhydride (PPN) in deionized water and in n -octanol

[摘要] The Henry's law solubility ( H S ) and liquid-phase loss rate constants ( k l ) of the tropospheric trace gas constituentsperoxyacetic nitric anhydride ( PAN ; CH 3 C(O)O 2 NO 2 , commonly known as peroxyacetyl nitrate) and peroxypropionic nitricanhydride ( PPN ; C 2 H 5 C(O)O 2 NO 2 , also known as peroxypropionyl nitrate) in deionized (DI) water and of PPN in n -octanolwere measured using a flow bubble apparatus at temperatures between 5.0 and 25.0  ∘ C . For PAN in DI water, the observed valuesfor  H S,aq are consistent with the literature, whereas the solubility of PPN in DI water is slightly lower than literaturevalues, ranging from H S cp ( PPN ) aq   =  (1.49  ±  0.05)  M atm −1 at 25.0  ∘ C to H S cp ( PPN ) aq   =  (7.01  ±  0.25)  M atm −1 at 5.0  ∘ C (stated uncertainties areat the 1 σ  level). The data are best described by ln ( H S cp ( PAN ) aq / [ M atm - 1 ] )   =   - ( 17.8 ± 0.3 )   +   ( 5620 ± 85 ) / T and ln ( H S cp ( PPN ) aq / [ M atm - 1 ] )   =   - ( 19.5 ± 1.7 )   +   ( 5955 ± 480 ) / T , where T  is inkelvin. For n -octanol, the PPN solubility ranges from H S cp ( PPN ) oct   =   ( 88 ± 5 ) M atm - 1 at 25.0  ∘ C to H S cp oct   =   ( 204 ± 16 ) M atm - 1 at 5.0  ∘ C and is best described by ln ( H S cp ( PPN ) oct / [ M atm - 1 ] )   =   - ( 6.92 ± 0.75 )   +   ( 3390 ± 320 ) / T . n -Octanol–waterpartition coefficients ( K OW ) for PPN were determined for the first time, ranging from 59  ±  4 at 25.0  ∘ C to29  ±  3 at 5.0  ∘ C . Observed loss rate constants in DI water are consistent with recent literature and larger than the thermaldissociation rates for both PAN and PPN , consistent with a hydrolysis mechanism, whereas k l  values in n -octanol aresignificantly smaller than gas-phase dissociation rate constants, likely owing to a “cage effect” in the organic liquid. The results imply thatuptake of either PAN or PPN on cloud water and organic aerosol is negligible but that uptake of PPN may constitute anoverlooked source of peroxy radicals in organic aerosol.

[学科分类] 医学（综合）