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Title: Surface Complexation of Pb(II) on Amorphous Iron Oxide and Manganese Oxide: Spectroscopic and Time Studies

Abstract

Hydrous Fe and Mn oxides (HFO and HMO) are important sinks for heavy metals and Pb(II) is one of the more prevalent metal contaminants in the environment. In this work, Pb(II) sorption to HFO (Fe{sub 2}O{sub 3}{center_dot}nH{sub 2}O, n=1-3) and HMO (MnO{sub 2}) surfaces has been studied with EXAFS: mononuclear bidentate surface complexes were observed on FeO{sub 6} (MnO{sub 6}) octahedra with Pb{single_bond}O distance of 2.25-2.35 Angstroms and Pb{single_bond}Fe(Mn) distances of 3.29-3.36 (3.65-3.76) Angstroms. These surface complexes were invariant of pH 5 and 6, ionic strength 2.8x10{sup -3} to 1.5x10{sup -2}, loading 2.03x10{sup -4} to 9.1 x 10{sup -3} mol Pb/g, and reaction time up to 21 months. EXAFS data at the Fe K-edge revealed that freshly precipitated HFO exhibits short-range order; the sorbed Pb(II) ions do not substitute for Fe but may inhibit crystallization of HFO. Pb(II) sorbed to HFO through a rapid initial uptake ({approx}77%) followed by a slow intraparticle diffusion step ({approx}23%) resulting in a surface diffusivity of 2.5x10{sup -15} cm{sup 2}/s. Results from this study suggest that mechanistic investigations provide a solid basis for successful adsorption modeling and that inclusion of intraparticle surface diffusion may lead to improved geochemical transport depiction.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
914129
Report Number(s):
BNL-78697-2007-JA
Journal ID: ISSN 0021-9797; JCISA5; TRN: US0801562
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Colloid Interface Sci.; Journal Volume: 299; Journal Issue: 1-3
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ADSORPTION; CRYSTALLIZATION; DIFFUSION; HEAVY METALS; IRON OXIDES; MANGANESE OXIDES; OXIDES; SORPTION; TRANSPORT; NSLS; national synchrotron light source

Citation Formats

Xu,Y., Boonfueng, T., Axe, L., Maeng, S., and Tyson, T.. Surface Complexation of Pb(II) on Amorphous Iron Oxide and Manganese Oxide: Spectroscopic and Time Studies. United States: N. p., 2006. Web. doi:10.1016/j.jcis.2006.01.041.
Xu,Y., Boonfueng, T., Axe, L., Maeng, S., & Tyson, T.. Surface Complexation of Pb(II) on Amorphous Iron Oxide and Manganese Oxide: Spectroscopic and Time Studies. United States. doi:10.1016/j.jcis.2006.01.041.
Xu,Y., Boonfueng, T., Axe, L., Maeng, S., and Tyson, T.. Sun . "Surface Complexation of Pb(II) on Amorphous Iron Oxide and Manganese Oxide: Spectroscopic and Time Studies". United States. doi:10.1016/j.jcis.2006.01.041.
@article{osti_914129,
title = {Surface Complexation of Pb(II) on Amorphous Iron Oxide and Manganese Oxide: Spectroscopic and Time Studies},
author = {Xu,Y. and Boonfueng, T. and Axe, L. and Maeng, S. and Tyson, T.},
abstractNote = {Hydrous Fe and Mn oxides (HFO and HMO) are important sinks for heavy metals and Pb(II) is one of the more prevalent metal contaminants in the environment. In this work, Pb(II) sorption to HFO (Fe{sub 2}O{sub 3}{center_dot}nH{sub 2}O, n=1-3) and HMO (MnO{sub 2}) surfaces has been studied with EXAFS: mononuclear bidentate surface complexes were observed on FeO{sub 6} (MnO{sub 6}) octahedra with Pb{single_bond}O distance of 2.25-2.35 Angstroms and Pb{single_bond}Fe(Mn) distances of 3.29-3.36 (3.65-3.76) Angstroms. These surface complexes were invariant of pH 5 and 6, ionic strength 2.8x10{sup -3} to 1.5x10{sup -2}, loading 2.03x10{sup -4} to 9.1 x 10{sup -3} mol Pb/g, and reaction time up to 21 months. EXAFS data at the Fe K-edge revealed that freshly precipitated HFO exhibits short-range order; the sorbed Pb(II) ions do not substitute for Fe but may inhibit crystallization of HFO. Pb(II) sorbed to HFO through a rapid initial uptake ({approx}77%) followed by a slow intraparticle diffusion step ({approx}23%) resulting in a surface diffusivity of 2.5x10{sup -15} cm{sup 2}/s. Results from this study suggest that mechanistic investigations provide a solid basis for successful adsorption modeling and that inclusion of intraparticle surface diffusion may lead to improved geochemical transport depiction.},
doi = {10.1016/j.jcis.2006.01.041},
journal = {J. Colloid Interface Sci.},
number = 1-3,
volume = 299,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}