苯系物二次有机气溶胶金属有机络合物组分的表征实验研究  

Experimental study on characterization of metallo-organic complex components of aromatic secondary organic aerosol

作　　者：曾志威 黄明强 朱敏聪 张丽梅 赵卫雄 胡长进 顾学军 张为俊[2] ZENG Zhiwei;HUANG Mingqiang;ZHU Mincong;ZHANG Limei;ZHAO Weixiong;HU Changjin;GU Xuejun;ZHANG Weijun(Fujian Provincial Key Laboratory of Modern Analytical Science and Separation Technology,College of Chemistry&Chemical Engineering and Environment,Minnan Normal University,Zhangzhou 363000;Laboratory of Atmospheric Physico-Chemistry,Anhui Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Hefei 230031)

机构地区：[1]闽南师范大学化学化工与环境学院,福建省现代分离分析科学与技术重点实验室,漳州363000 [2]中国科学院安徽光学精密机械研究所大气物理化学实验室,合肥230031

出　　处：《环境科学学报》2024年第8期159-169,共11页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金(No.42275136);福建省自然科学基金(No.2021J01987,2020J02044)。

摘　　要：大气二次有机气溶胶(SOA)金属有机络合物组分具有较强的吸光能力和生物毒性,可加重灰霾污染,危害人体健康.本文利用烟雾箱系统模拟氯化铁细粒子存在时,苯系物大气化学过程产生SOA粒子,采用在线质谱和离线光谱表征金属有机络合物的化学组分和光学性质.气溶胶激光飞行时间质谱在线测量和电喷雾电离质谱的离线验证表明,邻苯二酚类合铁(III)、二邻苯二酚类合铁(III)、二氯邻苯二酚类合铁(III)是苯系物SOA粒子主要的金属有机络合物组分.氯化铁细粒子存在时,苯系物SOA粒子的吸光能力显著增强,并具有荧光特性,最大激发和发射波长约为λ_(ех)/λ_(em)=704 nm/740 nm. SOA在200~1000 nm范围内的平均质量吸收系数(<MAC>)在186~732 cm^(2)·g^(-1)之间.苯环上存在甲基和乙基等取代基时,空间位阻效应阻碍OH自由基加成到苯环上.乙烯基存在时,其C=C键与苯环C=C键形成共轭双键,乙烯基电子离域到苯环上,使其电子云密度显著增强,加合反应更易发生.苯系物SOA粒子质量浓度、、发射740 nm荧光强度呈现1,2,4-三甲苯<对-二甲苯<甲苯<乙苯<苯<苯乙烯的规律.这为大气人为源SOA金属有机络合物化学组分和光学性质研究提供了实验参考和依据.Metallo-organic complex components of atmospheric secondary organic aerosol(SOA)have strong light absorption ability and biological toxicity,aggravating haze pollution and endangering human health.Somg chamber is used to simulate the atmospheric chemical process of aromatic compounds to generate SOA particles in presence of ferric chloride fine particles in this study.Chemical components and optical properties of metalloorganic complexes are characterized by on-line mass spectrometer and off-line spectral instrument.The on-line measurement of aerosol laser time-offlight mass spectrometer and off-line verification of electrospray ionization mass spectrometer show that catechol based iron(III),dicatechol based iron(III)and dichloro-catechol based iron(III)are main metallo-organic complex components of aromatic SOA.In presence of ferric chloride fine particles,the light absorption capacity of aromatic SOA is significantly enhanced and exhibited fluorescence characteristics.The maximum excitation and emission wavelength is approximately atλ_(ex)/λ_(em)=704 nm/740 nm.While,average mass absorption coefficient(<MAC>)of aromatic SOA in 200~1000 nm is between 186~732 cm^(2)·g^(-1).When substituents such as methyl and ethyl are present in benzene ring,steric hindrance effect hinders the addition of OH radical to benzene ring.In presence of vinyl,its C=C bond forms conjugated double bond with C=C bond of benzene ring,and vinyl electrons delocalize to benzene ring,significantly enhancing its electron cloud density and leading addition reactions more likely to occur.Aromatic SOA particles’mass concentration,<MAC>and fluorescence intensity of emitted 740 nm exhibit the pattern of 1,2,4-trimethylbenzene<p-xylene<toluene<ethylbenzene<benzene<styrene.These results provide experimental reference and basis for the study of chemical components and optical properties of metallo-organic complex components in atmospheric anthropogenic SOA particles.

关 键 词：二次有机气溶胶 金属有机络合物 苯系物 氯化铁 光学特性 

分 类 号：X131.1[环境科学与工程—环境科学]