Smog Chamber Simulation Of Atmospheric Photochemical Reactions Of Vinyl Acetate And NOx

Ozone(O3)and secondary organic aerosol(SOA),as important pollutants in urban atmosphere,are generated by photochemical reactions of nitrogen oxides(NOx)and volatile organic compounds(VOCs).Photochemical pollution has become the primary problem in air treatment.In this dissertation,vinyl acetate(C4H6O2),a typical pollutant in the pharmaceutical industry,was selected to simulate the X-ray chemical reaction of C4H6O2-NOx in a laboratory-made smoke box,and the effects of light intensity,initial concentration ratio of reactants and humidity on the photochemical reaction were investigated.Fourier transform infrared gas analyzer(Antaris IGS)was used to analyze the gas phase products,and gas chromatography-mass spectrometry(GC-MS)was used to analyze the particle phase products.The photochemical reaction mechanism of C4H6O2-NOx was discussed.Simulation experiments show that light intensity,initial concentration ratio of reactants and humidity have important effects on photochemical reactions.Under the irradiation of ultraviolet light,C4H6O2 and NO2 react to generate a large amount of O3 and SOA.The increase of illumination intensity accelerates the decomposition of C4H6O2 and promotes the large amount of O3 and SO A,which has a positive effect on the reaction.The initial concentration ratio of reactants promotes the growth of SOA particle size and quantity,which is positively correlated with O3 generation.Humidity promotes the photochemical reaction of C4H6O2,but inhibits the generation of O3.The number of SOA decreases slightly.It is estimated the particle size increases.The flexural vibration of C-H in cis-RCH=CHR',the stretching vibration of C=O in ketone,carboxylic acid and ester,the stretching vibration of C=O in aldehyde,the absorption peak of CO2,and the stretching vibration of O-H from free alcohols were detected by Fourier transform infrared gas analyzer(IGS).Hexyl formate,formaldehyde and acetic acid may be detected by GC-MS.