Phenanthrene and Pyrene Sorption and Intraparticle Diffusion in Polyoxymethylene, Coke, and Activated Carbon
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- 作者：Sungwoo Ahn ; David Werner ; Hrissi K. Karapanagioti ; Donald R. McGlothlin ; Richard N. Zare ; and Richard G. Luthy
- 刊名：Environmental Science & Technology
- 出版年：2005
- 出版时间：September 1, 2005
- 年：2005
- 卷：39
- 期：17
- 页码：6516 - 6526
- 全文大小：508K
- 年卷期：v.39,no.17(September 1, 2005)
- ISSN：1520-5851
文摘
We report sorption isotherms and uptake kinetics forphenanthrene and pyrene with three organic modelsorbents: polyoxymethylene (POM), coke, and activatedcarbon. We combine batch equilibration and kineticexperiments with the direct observation of the long-termdiffusion of phenanthrene and pyrene as measured withincross-sectioned particles using microprobe laser-desorption laser-ionization mass spectroscopy (
L2MS).For POM pellets, the intraparticle concentration profilespredicted from kinetic batch experiments and a polymerdiffusion model with spherical geometry are in agreementwith the independent L2MS measurements. For cokeparticles, the apparent diffusivities decreased with smallerparticle size. These trends in diffusivities were describedby a sorption-retarded pore diffusion model with a particle-size-dependent solid-water partitioning coefficientobtained from apparent equilibrium observed in the kineticbatch studies. For activated carbon, the L2MS measurements showed faster radial diffusion of phenanthrene andpyrene into the particle interior than predicted fromdiffusion models based on a single sorption domain anddiffusivity. A branched pore kinetic model, comprisingpolycyclic aromatic hydrocarbon (PAH) macropore diffusionwith kinetic exchange of PAH between macroporousand microporous domains, fits the experimental observationsbetter. Because of parallel macro- and microdiffusionprocesses, nonlinear sorption isotherms, and a concentration-dependent diffusivity, it is not possible to make independentparameter estimations for intraparticle diffusion inactivated carbon using our present procedures.
L2MS).For POM pellets, the intraparticle concentration profilespredicted from kinetic batch experiments and a polymerdiffusion model with spherical geometry are in agreementwith the independent L2MS measurements. For cokeparticles, the apparent diffusivities decreased with smallerparticle size. These trends in diffusivities were describedby a sorption-retarded pore diffusion model with a particle-size-dependent solid-water partitioning coefficientobtained from apparent equilibrium observed in the kineticbatch studies. For activated carbon, the L2MS measurements showed faster radial diffusion of phenanthrene andpyrene into the particle interior than predicted fromdiffusion models based on a single sorption domain anddiffusivity. A branched pore kinetic model, comprisingpolycyclic aromatic hydrocarbon (PAH) macropore diffusionwith kinetic exchange of PAH between macroporousand microporous domains, fits the experimental observationsbetter. Because of parallel macro- and microdiffusionprocesses, nonlinear sorption isotherms, and a concentration-dependent diffusivity, it is not possible to make independentparameter estimations for intraparticle diffusion inactivated carbon using our present procedures.