TY - JOUR
T1 - Modeling Pb sorption to microporous amorphous oxides as discrete particles and coatings
AU - Fan, Ming
AU - Boonfueng, Thipnakarin
AU - Xu, Ying
AU - Axe, Lisa
AU - Tyson, Trevor A.
N1 - Funding Information: This material is based upon work supported by the National Science Foundation under Grant BES 0089903. The authors also gratefully acknowledge support from the U.S. Army Sustainable Green Manufacturing program through the National Defense Center for Environmental Excellence (Contract DAAE30-98-C-1050) and the DuPont Young Professor Grant. The authors thank Wanchun Yuan for conducting preliminary experiments.
PY - 2005/1/1
Y1 - 2005/1/1
N2 - Hydrous amorphous Al (HAO), Fe (HFO), and Mn (HMO) oxides are ubiquitous in the subsurface as both discrete particles and coatings and exhibit a high affinity for heavy metal contaminants. To assess risks associated with heavy metals, such as Pb, to the surrounding environment and manage remedial activities requires accurate mechanistic models with well-defined transport parameters that represent sorption processes. Experiments were conducted to evaluate Pb sorption to microporous Al, Fe, and Mn oxides, as well as to montmorillonite and HAO-coated montmorillonite. Intraparticle diffusion, a natural attenuating process, was observed to be the rate-limiting mechanism in the sorption process, where best-fit surface diffusivities ranged from 10 -18 to 10 -15 cm 2 s -1. Specifically, diffusivities of Pb sorption to discrete aluminum oxide, aluminum oxide-coated montmorillonite, and montmorillonite indicated substrate surface characteristics influence metal mobility where diffusivity increased as affinity decreased. Furthermore, the diffusivity for aluminum oxide-coated montmorillonite was consistent with the concentrations of the individual minerals present and their associated particle size distributions. These results suggest that diffusivities for other coated systems can be predicted, and that oxide coatings and montmorillonite are effective sinks for heavy metal ions.
AB - Hydrous amorphous Al (HAO), Fe (HFO), and Mn (HMO) oxides are ubiquitous in the subsurface as both discrete particles and coatings and exhibit a high affinity for heavy metal contaminants. To assess risks associated with heavy metals, such as Pb, to the surrounding environment and manage remedial activities requires accurate mechanistic models with well-defined transport parameters that represent sorption processes. Experiments were conducted to evaluate Pb sorption to microporous Al, Fe, and Mn oxides, as well as to montmorillonite and HAO-coated montmorillonite. Intraparticle diffusion, a natural attenuating process, was observed to be the rate-limiting mechanism in the sorption process, where best-fit surface diffusivities ranged from 10 -18 to 10 -15 cm 2 s -1. Specifically, diffusivities of Pb sorption to discrete aluminum oxide, aluminum oxide-coated montmorillonite, and montmorillonite indicated substrate surface characteristics influence metal mobility where diffusivity increased as affinity decreased. Furthermore, the diffusivity for aluminum oxide-coated montmorillonite was consistent with the concentrations of the individual minerals present and their associated particle size distributions. These results suggest that diffusivities for other coated systems can be predicted, and that oxide coatings and montmorillonite are effective sinks for heavy metal ions.
KW - Hydrous aluminum oxide
KW - Hydrous iron oxide
KW - Hydrous manganese oxide
KW - Intraparticle diffusion
KW - Lead
KW - Montmorillonite
KW - Oxide coating
KW - Sorption
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U2 - 10.1016/j.jcis.2004.08.050
DO - 10.1016/j.jcis.2004.08.050
M3 - Article
C2 - 15567378
SN - 0021-9797
VL - 281
SP - 39
EP - 48
JO - Journal of Colloid And Interface Science
JF - Journal of Colloid And Interface Science
IS - 1
ER -