Atmospheric heterogeneous reaction of acetone:Adsorption and desorption kinetics and mechanisms on SiO_2 particles  

作　　者：JIE ChongYu CHEN ZhongMing WANG HongLi HUA Wei WANG CaiXia LI Shuang 

机构地区：[1]The State Key Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering Peking University, Beijing 100871, China

出　　处：《Chinese Science Bulletin》2008年第7期1004-1010,共7页

基　　金：the National Natural Science Foundation of China (Grant Nos. 20677002 and 20107001);the Project of Development Plan of the State Key Fundamental Research (Grant No. 2002CB410802)

摘　　要：Acetone plays an important role in photooxidation processes in the atmosphere. Up to date, little is known regarding the heterogeneous fate of acetone. In this study, the adsorption and desorption processes of acetone on SiO2 particles, which are the major constituent of mineral dust in the atmos-phere, have been investigated for the first time under the simulated atmospheric conditions, using in situ transmission Fourier transform infrared spectroscopy. It is found that acetone molecules are ad-sorbed on the surfaces of SiO2 particles by van der Waals forces and hydrogen bonding forces in a nonreactive and reversible state. The rates of initial adsorption and initial desorption, initial uptake coefficients and adsorption concentrations at equilibrium have been determined at different relative humidity. The presence of water vapor cannot result in the formation of new substances, but can de-crease the adsorption ability by consuming or overlapping the isolated OH groups on the surfaces of SiO2 particles. In the desorption process, a considerable amount of acetone molecules will remain on SiO2 particles in dry air, whereas acetone molecules are almost completely desorbed at a high relative humidity. In order to evaluate the role of heterogeneous reactions of acetone and other carbonyl compounds in the atmosphere, a new model fitting the atmospheric conditions is needed.Acetone plays an important role in photooxidation processes in the atmosphere. Up to date, little is known regarding the heterogeneous fate of acetone. In this study, the adsorption and desorption processes of acetone on SiO2 particles, which are the major constituent of mineral dust in the atmos-phere, have been investigated for the first time under the simulated atmospheric conditions, using in situ transmission Fourier transform infrared spectroscopy. It is found that acetone molecules are adsorbed on the surfaces of SiO2 particles by van der Waals forces and hydrogen bonding forces in a nonreactive and reversible state. The rates of initial adsorption and initial desorption, initial uptake coefficients and adsorption concentrations at equilibrium have been determined at different relative humidity. The presence of water vapor cannot result in the formation of new substances, but can decrease the adsorption ability by consuming or overlapping the isolated OH groups on the surfaces of SiO2 particles. In the desorption process, a considerable amount of acetone molecules will remain on SiO2 particles in dry air, whereas acetone molecules are almost completely desorbed at a high relative humidity. In order to evaluate the role of heterogeneous reactions of acetone and other carbonyl compounds in the atmosphere, a new model fitting the atmospheric conditions is needed.

关 键 词：丙酮 大气反射 吸附作用 脱附作用 二氧化硅 

分 类 号：O433[机械工程—光学工程]