Photochemical Reaction Of HNO₃on Typical Particle Surface （SiO₂、Al₂O₃and Fe₂O₃）

The mechanism of the reaction of photolysis of HNO3and photochemicalreaction of HNO3on the surface of SiO2, Al2O3and Fe2O3at308nm UV light,365nm UV light （secondary light source254nm UV light）and in the dark wereinvestigated, using ultraviolet spectrograph and ion chromatogram. In addition, theeffect of different factors (time, concentration, humidity，temperature) on the reactionswas also studied in this paper. The results are as follows：HNO3gas phase photodissociation experiments suggested that the concentrationof NO2and NO production increased with the increase of illumination time，HNO3initial concentration and temperature. However, the NO2concentration of HNO3photolysis in the gas phase decreased as the relative humidity increased and the NOconcentration increased gradually. When HNO3initial concentration of was400Pa,reaction temperature was25℃and exposured to75min at308nm UV light, NO2and NO concentration could reach5.19×1015molecule/cm3and2.32×1015molecule/cm3，respectively. Exposured to75min at365nm UV light, NO2and NOconcentration could reach4.52×1015molecule/cm3and2.02×1015molecule/cm3，respectively.The dark reaction of HNO3on the SiO2，Al2O3and Fe2O3surface showed thatadsorption coefficient γ of400Pa HNO3on the SiO2，Al2O3and Fe2O3were3.03×10-9，3.97×10-9and4.31×10-9，respectively. The photochemical reaction ofHNO3on the surface of SiO2，Al2O3and Fe2O3showed that the main gas-phaseproduct NO2and NO concentration and NO3-, NO2-production showed an increasewith the increase of irradiation time，initial concentration of HNO3and temperature.However, the NO2concentration of HNO3photolysis on the SiO2，Al2O3and Fe2O3surface decreased as the relative humidity increased and the NO concentrationincreased gradually. In the presence of water vapor, the gas products of reactions weremeasured by FTIR. The study showed that HONO was produced in the reaction andwith the increase of relative humidity（10%-90%）, the HONO concentration slowincreased. When HNO3initial concentration of was400Pa, reaction temperature was25℃and exposured to75min at308nm UV light, NO2and NO concentration fromphotochemical reaction of HNO3on the surface of SiO2could reach17.19×1015molecule/cm3and4.01×1015molecule/cm3，respectively. Exposured to75min at308nm UV light, NO2and NO concentration from photochemical reaction of HNO3on the surface of Al2O3could reach1.96×1016molecule/cm3and8.77×1015molecule/cm3，respectively. Exposured to75min at308nm UV light, NO2and NOconcentration from photochemical reaction of HNO3on the surface of Fe2O3couldreach2.22×1016molecule/cm3and1.13×1016molecule/cm3，respectively. Exposured to75min at365nm UV light, NO2and NO concentration from photochemical reactionof HNO3on the surface of SiO2could reach1.53×1016molecule/cm3and3.58×1015molecule/cm3，respectively. Exposured to75min at365nm UV light, NO2and NOconcentration from photochemical reaction of HNO3on the surface of Al2O3couldreach1.70×1016molecule/cm3and7.59×1015molecule/cm3，respectively. Exposured to75min at365nm UV light, NO2and NO concentration from photochemical reactionof HNO3on the surface of Fe2O3could reach1.90×1016molecule/cm3and9.68×1015molecule/cm3，respectively.The NOxconcentration from photochemical reaction of HNO3on the surface ofSiO2，Al2O3and Fe2O3is about3times than HNO3photolysis in the gas phase. Underthe same experimental conditions，the effect of photolysis：Fe2O3>Al2O3>SiO2...