Role of aerosols in enhancing SVOC flux between air and indoor surfaces and its influence on exposure
Role of aerosols in enhancing SVOC flux between air and indoor surfaces and its influence on exposure
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气溶胶在增强空气和室内表面之间 SVOC 通量方面的作用及其对暴露的影响
DOI：
10.1016/j.atmosenv.2012.03.030
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发表时间：
2012-08-01
影响因子：
5
通讯作者：
Zhang, Yinping
中科院分区：
文献类型：
--
作者：
Liu, Cong;Morrison, Glenn C.;Zhang, Yinping
室内表面在建筑物内半挥发性有机化合物(SVOCs)的运输和暴露中起着重要的作用。在这项研究中，我们建立了一个模型来解释颗粒介导的SVOC传输，发现由于大的气固两相分配系数以及布朗系数和气体扩散系数的巨大差异，在颗粒的存在下，SVOC跨浓度边界层的传输显著增强。确定了两个重要的无量纲参数Bim，Big和Bim，Big/(m，p)：Bim，Big是1)SVOC通过浓度边界层传输的特征时间与2)边界层被颗粒“扫”或通过释放SVOCs而“饱和”的特征时间之比。该参数可视为无量纲传质系数。Bim，Big/Bim，Bip表征了与颗粒相关的SVOC质量，相对于气相中的SVOCs。对单分散颗粒的分析表明，对于较大的颗粒/气体分配系数(log K部分=13)、较小的颗粒(d(P)接近0.1微米)和较小的自由流动速度(U无限=0.01m S(-1))，在无颗粒的情况下，通量可提高5倍以上。随着颗粒直径的减小，通量增强趋于增大。然而，随着颗粒变得非常小(例如，d(P)和lt；0.05µm)，具有logK-Part=13的SVOCs的通量增强略有下降。大于2微米的颗粒对通量没有显著影响。对于与典型室内环境、烹饪和吸烟相关的多分散颗粒物，发现其结果符合指数相关性。两个算例表明，1)邻苯二甲酸二(2-乙基己基)酯(DEHP)在气体和表面之间达到平衡的时间从3.0年缩短到0.45年；2)在颗粒存在的情况下，我们的模型预测的气相DEHP浓度和排放速率比先前模型估计的高4倍。颗粒介导的SVOCs的气相传输可以导致乘员暴露增加4-10倍。(C)爱思唯尔有限公司出版的2012年。
Indoor surfaces play an important role in the transport of, and exposure to, semi-volatile organic compounds (SVOCs) in buildings. In this study, we develop a model that accounts for SVOC transport mediated by particles and find that, due to large gas-particle partition coefficients along with large differences in Brownian and gas diffusivities, SVOC transport across concentration boundary layers is significantly enhanced in the presence of particles. Two important dimensionless parameters, Bi-m,Bi-g and Bi-m,Bi-g/(m,p), were identified: Bi-m,Bi-g is the ratio of 1) the characteristic time for the SVOC to transport across the concentration boundary layer to 2) the characteristic time for boundary layer to either be "swept" of SVOCs by particles or "saturated" by release of SVOCs from particles. This parameter can be regarded as a dimensionless mass transfer coefficient. Bi-m,Bi-g/Bi-m,Bi-p characterizes the SVOC mass associated with particles, relative to SVOCs in the gas-phase. Analysis on monodisperse particles shows that flux can be enhanced by as much as a factor of 5 over transport in the absence of particles, for a large particle/gas partition coefficient (log K-part = 13), small particles (d(p) similar to 0.1 mu m) and a small free stream velocity (U-infinity = 0.01 m s(-1)). As particle diameter decreases, flux enhancement tends to increase. However, as particles become very small (e.g., d(p) < 0.05 mu m), flux enhancement for SVOCs with log K-part = 13 decreases slightly. Particles larger than 2 mu m do not significantly influence the flux. An exponential correlation is found to fit the results for polydisperse particles associated with typical indoor environments, cooking and smoking. Two illustrative examples are used to show that, 1) the timescale for di(2-ethylhexyl) phthalate (DEHP) to approach equilibrium between the gas and a surface is shortened from 3.0 years to 0.45 years; and 2) in the presence of particles, the gas-phase DEHP concentration and emission rate are predicted to be as much as 4 times higher by our model than that by prior model estimates. Particle mediated gas-phase transport of SVOCs can result an increase in occupant exposure by a factor of 4-10. (C) 2012 Published by Elsevier Ltd.