A distributed reactivity model for sorption by sails and sediments. 14. Characterization and modeling of phenanthrene desorption rates

作者：Johnson MD; Keinath TM; Weber WJ^*

来源：Environmental Science & Technology, 2001, 35(8): 1688-1695.

DOI：10.1021/es001391k

Rates and extents of phenanthrene desorption were studied for more than 250 days as functions of sorbent type, initial loading level, and aging. Apparent first-order desorption rate constants for the slowly desorbing fraction were found to ii) range from 0.00086 to 0.148 days(-1) for geosorbents that contain geologically mature kerogen and less rigid humic-type soil organic matter, respectively, (ii) decrease by as much as an order of magnitude with decreasing initial sorbed solid-phase phenanthrene concentration, (iii) decrease by a factor of 2 with increasing aging time far a humic topsoil but remain unaffected by aging time beyond 3 months for a shale, and (iv) be 1-2 ord e rs of magnitude lower than rate constants for th e rapidly desorbing phenanthrene fractions for any given contaminated sample. Six models were used to fit the desorption rate data. Biphasic diffusion and biphasic first-order models with three fitting parameters possess broad utility and are potentially useful in a variety of environmental applications. Disadvantages of a five-parameter triphasic first-order desorption model, a two-parameter gamma-function model, and a one- or two-parameter pore diffusion model are also discussed.

• 出版日期2001-4-15