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有机胺在高岭土上的摄取动力学
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摘要
作为一类重要的含氮有机物,有机胺不仅对大气氮沉降有贡献1,其在新粒子生成与细粒子增长和棕色碳生成等过程中也具有重要作用2。研究有机胺的大气化学过程,对理解有机氮的大气化学循环具有重要意义3。研究发现颗粒物中无机铵盐和有机酸可摄取有机胺4,并可能是颗粒态有机氮的重要来源。矿质颗粒物是大气颗粒物的重要组成部分。由于缺乏其对有机胺的摄取动力学常数,还无法评估矿质颗粒物对颗粒态有机氮大气化学循环的贡献。本文利用努森池质谱系统系统研究了甲胺、二甲胺和三甲胺在高岭土上的摄取动力学。300 K,摄取系数分别为2.33±0.17?10-3,1.68±0.24?10-3和2.95±0.63?10-3,与有机胺在无机盐上的摄取相当。进一步在230-300 K范围内,研究了温度对摄取动力学的影响,测定了脱附活化能、吸附热和吸附熵等参数;并讨论了有机胺碱性与摄取动力学的关系。该结果有助于全面理解有机胺的大气化学循环过程。
Amines are related to not only atmospheric nitrogen deposition but also new particle and brown carbon formation.It is important to investigate the chemical cycle of amines for understanding the nitrogen cycle in the atmosphere.It has been found that uptake by ammoniums and organic acids contributes to particulate organic nitrogen.Mineral dust is an important component of atmospheric particle,while it is unknown about the contribution of mineral dust to the chemical cycle of amines because of the missed uptake kinetics.The uptake kinetics(?) of methylamine,dimethylamine and trimethylamine on kaolin has been investigated using a Knudsen cell reactor in this study.The corresponding ? is 2.33±0.17?10-3,1.68±0.24?10-3 and 2.95±0.63?10-3 at 300 K,which is comparable with the ? of amines on ammoniums.The adsorption energy,enthalpy and entropy have been measured based on the uptake kinetics in the temperature range of 230-300 K.The influence of the basicity of amines on kinetics has been further discussed.The results will help to understand the chemical cycle of amines in the atmosphere.
引文
1.Meunier,C.L.;Gundale,M.J.;Sanchez,I.S.;Liess,A.,Glob.Change Biol.2016,22(1),164-179.
    2 .Qiu,C.;Zhang,R.,Phys.Chem.Chem.Phys.2013,15(16),5738-5752.
    3 .Keene,W.C.;Montag,J.A.;Maben,J.R.;Southwell,M.et al.Atmos.Environ.2002,36(28),4529-4540.
    4 .(a)Liu,Y.;Ma,Q.;He,H.,Environ.Sci Technol.2012,46,11112-11118;(b)Liu,Y.;Han,C.;Liu,C.;Ma,J.et al.Atmos.Chem.Phys.2012,12(11),4855-4865.

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