Laboratory Studies of Potential Mechanisms of Renoxification of Tropospheric Nitric Acid

Abstract

Laboratory studies of the heterogeneous reactions between HNO3 in thin water films on silica surfaces and gaseous NO, CO, CH4, and SO2, proposed as potential "renoxification" mechanisms in the atmosphere, are reported. Transmission FTIR was used to monitor reactants and products on the silica surface and in the gas phase as a function of time. No reaction of CO, CH4, or SO2 was observed; upper limits to the reaction probabilities (gamma(rxn)) are < or = 10(-10) for CO and SO2 and < or = 10(-12) for CH4. However, the reaction of HNO3 with NO does occur with a lower limit for the reaction probability of gammaNO > or = (6 +/- 2) x 10(-9) (2s). The experimental evidence shows that the chemistry is insensitive to whether the substrate is pure silica or borosilicate glass. Nitric acid in its molecular form, and not the nitrate anion form, was shown to be the reactive species, and NH4NO3 was shown not to react with NO. The HNO3-NO reaction could be a significant means of renoxification of nitric acid on the surfaces of buildings and soils in the boundary layer of polluted urban atmospheres. This chemistry may help to resolve some discrepancies between model-predicted ozone and field observations in polluted urban atmospheres.

Structure–activity relationship of surface hydroxyl groups during NO2 adsorption and transformation on TiO2 nanoparticles

“…The peaks observed in the range of 1200-1700 cm −1 are due to the formation of surface species, while the negative peaks in the range of 3600-3800 cm −1 were attributed to the consumption of surface OH groups. Detailed assignments of the surface species are summarized in Table S2 30,[32][33][34] These two peaks were attributed to the asymmetric and symmetric stretching modes of surfaceadsorbed HNO 3 , respectively. In this work, the band at 1310 cm −1 could be resolved by spectrum deconvolution fitting analysis (Fig.…”

Combined impacts of nitrous acid and nitryl chloride on lower-tropospheric ozone: new module development in WRF-Chem and application to China

“…being used for Reaction (R7) (Rivera-Figueroa et al, 2003) and light-density-dependent values as introduced in being employed for Reaction (R8).…”

Interactions of gaseous nitric acid with surfaces of environmental interest

“…For example, HNO 3 on surfaces has been shown to react with NO to form gas phase NO 2 . [2][3][4][5][6][7][8][9][10][11][12][13] To date, the impacts of deposited HNO 3 on the composition and chemistry of the thin surface films, which potentially have important implications for chemistry in the boundary layer, have not been explored. For example, Diamond et al…”