Ozonation Mechanism Of Atmospheric Organic Amine And Its Effect On The Formation Of Fine Particles

Organic amines are one of the most important nitrogen-containing compounds in the atmosphere.Because of their strong alkalinity and high reactivity,they are widely active in atmospheric chemical reactions,such as free radical oxidation,acid-base reaction,heterogeneous reaction,and deposition reaction.Nitrogen-containing and oxygen-containing compounds,organic amine salts were frequently produced by the reaction and even organic amines directly or indirectly to promote the formation of atmospheric fine particles.Although there have been many studies focused on the reaction of atmospheric organic amines with free radicals and the reaction kinetics,the ozone oxidation mechanism as well as the oxidation pathways of organic amines in the atmosphere and their impact on atmospheric fine particle production still require further exploration.In the experiment of this subject,the ozonation pathway and mechanism of ozone decomposition of two typical organic amines(diethylamine and triethylamine)in the atmosphere were studied through experimental and theoretical methods.Specifically,through the offline and online analysis of gas-chromatography mass spectrometer,proton transfer reaction time-of-flight mass spectrometer,and proton transfer reaction quadrupole mass spectrometer,the qualitative and quantitative analysis of the degradation products of diethylamine and triethylamine by ozone were conducted,the eight and eleven nitrogencontaining and oxygen-containing products were identified and quantitatively analyzed,respectively.It was found that N-ethylethaneamine(average 56.5%)or acetaldehyde(average 64.9%)were found to be the main products of ozonolysis of two organic amines,respectively.Then,according to the concentration and yield of each product,the ratio of each pathway was determined,and the mechanism of the ozonation reaction was summarized and combined with quantum chemical calculation.The results of the ozone oxidation pathway show that the conversion to N-ethylethaneamine is the main pathway for the ozonation of diethylamine;while triethylamine is more likely to be converted to diethylamine first and then release a large amount of acetaldehyde before convert to N-ethylethaneamine.For the monitoring of fine particles in the two systems,we found that due to the effect of high concentration of intermediate products(especially from acetaldehyde),the ozone decomposition process of triethylamine has a greater contribution to atmospheric nanoparticle formation than that of diethylamine.In addition,further research on the mechanism of aldehydes found that the dipropylamine ozone system with high aldehyde production has a larger particle number and mass concentration than the hexylamine system with very low aldehyde production,and the proportion of aldehydes artificially high The amount of aldehyde added in the amine ozone system will cause the concentration of the main organic products to increase in a short time,and the total mass concentration of the particulates will also increase.For the amine system with a very low proportion of aldehyde concentration,although the addition of aldehyde causes large particle size generation,but because it does not promote the synthesis of new particles and its own concentration loss decreases,it does not significantly increase the total mass concentration,only reflected in the increase in particle size.This work will provide a deeper understanding of the process and mechanism of ozonolysis and conversion of organic amines in the atmosphere and their impact on the formation of nanoparticles.