Intraparticle surface diffusion of metal contaminants and their attenuation in microporous amorphous Al, Fe, and Mn oxides.
Intraparticle surface diffusion is an important and rate-limiting process in the sorption of metal ions to microporous sorbents such as those of hydrous amorphous Al (HAO), Fe (HFO), and Mn (HMO) oxides; these minerals are abundant in the environment, exhibiting a high affinity for metal contaminants. In aquatic systems representative of natural environments, internal micropore surfaces of HAO, HFO, and HMO can account for 40 to 90% of the sorption sites. Surface diffusivities have been observed to range between 10(-16) and 10(-10) cm2 s(-1) for metals including Sr, Cd, Zn, and Ni. The combination of significant microporosity and small diffusivities results in the amorphous oxides acting as natural attenuating sinks.
Axe
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L
Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102, USA. axe@adm.njit.edu
Trivedi
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P