Determining PCB Sorption/Desorption Behavior on Sediments Using Selective Supercritical Fluid Extraction. 2. Describing PCB Extraction with Simple Diffusion Models
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- 作者：Karol Pilorz ; Erland Bjö ; rklund ; S
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- 刊名：Environmental Science & Technology
- 出版年：1999
- 出版时间：July 1, 1999
- 年：1999
- 卷：33
- 期：13
- 页码：2204 - 2212
- 全文大小：142K
- 年卷期：v.33,no.13(July 1, 1999)
- ISSN：1520-5851
文摘
A simple diffusion model is fitted to selective SFE profilesobtained in Part 1 for native (not spiked) PCBs inhistorically contaminated sediments and soils. The modeltakes two types of geometry into consideration, a sphericalone (Hot Ball, HB) and a planar one (Finite Slab, FS) andis extended to describe the influence of increasingtemperature during the extraction. In this work, soil/sediment organic matter (SOM) is treated as a polymer-like organic material (POM). Consequently, diffusion isconsidered to be an activated process where the diffusioncoefficients depend on the temperature according to theArrhenius equation. When using one type of POM in themodel, the characteristic "temperature humps" obtainedin the extraction profiles are simulated relatively well, butat least three types of POM are needed for excellentfits to experimental data. The final model, consisting ofthree different POMs with spherical geometry, was fittedto all matrixes to estimate diffusion coefficients and activationenergies. These data correlated with relevant literaturevalues obtained from long-term water desorption experiments,indicating that it might be possible to replace theseexperiments with rapid SFE to characterize soils andsediments and to predict the rate of release of pollutantsunder field conditions.