Quantifying the Effect of Medium Composition on the Diffusive Mass Transfer of Hydrophobic Organic Chemicals through Unstirred Boundary Layers
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- 作者：Philipp Mayer ; Ulrich Karlson ; Peter S. Christensen ; Anders R. Johnsen ; and Stefan Trapp
- 刊名：Environmental Science & Technology
- 出版年：2005
- 出版时间：August 15, 2005
- 年：2005
- 卷：39
- 期：16
- 页码：Mayer, Ulrich Karlso
- 全文大小：214K
- 年卷期：v.39,no.16(August 15, 2005)
- ISSN：1520-5851
文摘
Unstirred boundary layers (UBLs) often act as a bottleneckfor the diffusive transport of hydrophobic organiccompounds (HOCs) in the environment. Therefore, amicroscale technique was developed for quantifying masstransfer through a 100-
m thin UBL, with the mediumcomposition of the UBL as the controllable factor. The modelcompound fluoranthene had to (1) partition from acontaminated silicone disk (source) into the medium, (2)then diffuse through 100 m of medium (UBL), and finally (3)partition into a clean silicone layer (sink). The diffusivemass transfer from source to sink was monitored over timeby measuring the fluoranthene content of the sourceand sink disks. The diffusive flux of fluoranthene was slightlyhigher for air than for water. Cyclodextrin, humic acids,and micelles of sodium dodecyl sulfate (SDS) enhanced thediffusive flux of fluoranthene in water by more than 1order of magnitude. These results demonstrate that mediumconstituents, which normally are believed to bindhydrophobic organic chemicals, actually can enhance thediffusive mass transfer of HOCs in the vicinity of adiffusion source (e.g., contaminated soil particles). Thetechnique can be used to evaluate the effect of natural fluidson diffusive mass transfer, as it integrates the differentprocesses, partitioning and diffusion, in one laboratory model.
m thin UBL, with the mediumcomposition of the UBL as the controllable factor. The modelcompound fluoranthene had to (1) partition from acontaminated silicone disk (source) into the medium, (2)then diffuse through 100 m of medium (UBL), and finally (3)partition into a clean silicone layer (sink). The diffusivemass transfer from source to sink was monitored over timeby measuring the fluoranthene content of the sourceand sink disks. The diffusive flux of fluoranthene was slightlyhigher for air than for water. Cyclodextrin, humic acids,and micelles of sodium dodecyl sulfate (SDS) enhanced thediffusive flux of fluoranthene in water by more than 1order of magnitude. These results demonstrate that mediumconstituents, which normally are believed to bindhydrophobic organic chemicals, actually can enhance thediffusive mass transfer of HOCs in the vicinity of adiffusion source (e.g., contaminated soil particles). Thetechnique can be used to evaluate the effect of natural fluidson diffusive mass transfer, as it integrates the differentprocesses, partitioning and diffusion, in one laboratory model.