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Title: Humic Acid Metal Cation Interaction Studied by Spectromicroscopy Techniques in Combination with Quantum Chemical Calculations

Abstract

Humic acids (HA) have a high binding capacity towards traces of toxic metal cations, thus affecting their transport in aquatic systems. Eu(III)-HA aggregates are studied by synchrotron-based scanning transmission X-ray microscopy (STXM) at the carbon K-edge and laser scanning luminescence microscopy (LSLM) at the {sup 5}D{sub 0} {yields} {sup 7}F{sub 1,2} fluorescence emission lines. Both methods provide the necessary spatial resolution in the sub-micrometre range to resolve characteristic aggregate morphologies: optically dense zones embedded in a matrix of less dense material in STXM images correspond to areas with increased Eu(III) luminescence yield in the LSLM micrographs. In the C 1s-NEXAFS of metal-loaded polyacrylic acid (PAA), used as a HA model compound, a distinct complexation effect is identified. This effect is similar to trends observed in the dense fraction of HA/metal cation aggregates. The strongest complexation effect is observed for the Zr(IV)-HA/PAA system. This effect is confirmed by quantum chemical calculations performed at the ab initio level for model complexes with different metal centres and complex geometries. Without the high spatial resolution of STXM and LSLM and without the combination of molecular modelling with experimental results, the different zones indicating a 'pseudo'-phase separation into strong complexing domains and weaker complexing domainsmore » of HA would never have been identified. This type of strategy can be used to study metal interaction with other organic material.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
Sponsoring Org.:
DOE - OFFICE OF SCIENCE
OSTI Identifier:
1019817
Report Number(s):
BNL-95663-2011-JA
Journal ID: ISSN 0909-0495; JSYRES; TRN: US201115%%453
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Journal of Synchrotron Radiation
Additional Journal Information:
Journal Volume: 17; Journal Issue: 2; Journal ID: ISSN 0909-0495
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CAPACITY; CARBON; CATIONS; CHEMISTRY; FLUORESCENCE; HUMIC ACIDS; LASERS; LUMINESCENCE; MICROSCOPY; SPATIAL RESOLUTION; TRANSPORT; national synchrotron light source

Citation Formats

Plaschke, M, Rothe, J, Armbruster, M, Denecke, M, Naber, A, and Geckeis, H. Humic Acid Metal Cation Interaction Studied by Spectromicroscopy Techniques in Combination with Quantum Chemical Calculations. United States: N. p., 2010. Web. doi:10.1107/S0909049509048742.
Plaschke, M, Rothe, J, Armbruster, M, Denecke, M, Naber, A, & Geckeis, H. Humic Acid Metal Cation Interaction Studied by Spectromicroscopy Techniques in Combination with Quantum Chemical Calculations. United States. https://doi.org/10.1107/S0909049509048742
Plaschke, M, Rothe, J, Armbruster, M, Denecke, M, Naber, A, and Geckeis, H. 2010. "Humic Acid Metal Cation Interaction Studied by Spectromicroscopy Techniques in Combination with Quantum Chemical Calculations". United States. https://doi.org/10.1107/S0909049509048742.
@article{osti_1019817,
title = {Humic Acid Metal Cation Interaction Studied by Spectromicroscopy Techniques in Combination with Quantum Chemical Calculations},
author = {Plaschke, M and Rothe, J and Armbruster, M and Denecke, M and Naber, A and Geckeis, H},
abstractNote = {Humic acids (HA) have a high binding capacity towards traces of toxic metal cations, thus affecting their transport in aquatic systems. Eu(III)-HA aggregates are studied by synchrotron-based scanning transmission X-ray microscopy (STXM) at the carbon K-edge and laser scanning luminescence microscopy (LSLM) at the {sup 5}D{sub 0} {yields} {sup 7}F{sub 1,2} fluorescence emission lines. Both methods provide the necessary spatial resolution in the sub-micrometre range to resolve characteristic aggregate morphologies: optically dense zones embedded in a matrix of less dense material in STXM images correspond to areas with increased Eu(III) luminescence yield in the LSLM micrographs. In the C 1s-NEXAFS of metal-loaded polyacrylic acid (PAA), used as a HA model compound, a distinct complexation effect is identified. This effect is similar to trends observed in the dense fraction of HA/metal cation aggregates. The strongest complexation effect is observed for the Zr(IV)-HA/PAA system. This effect is confirmed by quantum chemical calculations performed at the ab initio level for model complexes with different metal centres and complex geometries. Without the high spatial resolution of STXM and LSLM and without the combination of molecular modelling with experimental results, the different zones indicating a 'pseudo'-phase separation into strong complexing domains and weaker complexing domains of HA would never have been identified. This type of strategy can be used to study metal interaction with other organic material.},
doi = {10.1107/S0909049509048742},
url = {https://www.osti.gov/biblio/1019817}, journal = {Journal of Synchrotron Radiation},
issn = {0909-0495},
number = 2,
volume = 17,
place = {United States},
year = {Fri Jan 01 00:00:00 EST 2010},
month = {Fri Jan 01 00:00:00 EST 2010}
}