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Title: Mechanism of Pb Adsorption to Fatty Acid Langmuir Monolayers Studied by X-ray Absorption Fine Structure Spectroscopy

Abstract

The local atomic environment of lead (Pb) adsorbed to a CH{sub 3}(CH{sub 2}){sub 19}COOH Langmuir monolayer was investigated in situ using grazing-incidence X-ray absorption fine structure (GI-XAFS) spectroscopy at the Pb L{sub III} edge. Measurements were performed at pH 6.5 of the 10{sup -5} M PbCl{sub 2} solution subphase, a condition under which grazing incidence diffraction (GID) revealed a large-area commensurate superstructure underneath the close-packed organic monolayer. The XAFS results indicate covalent binding of the Pb cations to the carboxyl headgroups, and the observed Pb-Pb coordination suggests that the metal is adsorbed as a hydrolysis polymer, rather than as individual Pb{sup 2+} ions. The data are consistent with a bidentate chelating mechanism and a one Pb atom to one carboxyl headgroup binding stoichiometry. We discuss how this adsorption model can explain the peculiarities observed with Pb in previous metal-Langmuir monolayer studies. A systematic study of lead perchlorate and lead acetate aqueous solutions is presented and used in the analysis. XAFS multiple scattering effects from alignment of the Pb-C-C atoms in the lead acetate solutions are reported.

Authors:
; ; ; ; ;  [1]
  1. NWU
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE
OSTI Identifier:
1008792
Resource Type:
Journal Article
Journal Name:
J. Phys. Chem. B
Additional Journal Information:
Journal Volume: 107; Journal Issue: (36) ; 08, 2003; Journal ID: ISSN 1520-6106
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION; ACETATES; ADSORPTION; ALIGNMENT; AQUEOUS SOLUTIONS; ATOMS; CARBOXYLIC ACIDS; CATIONS; DIFFRACTION; FINE STRUCTURE; HYDROLYSIS; LEAD PERCHLORATES; MULTIPLE SCATTERING; SPECTROSCOPY; STOICHIOMETRY

Citation Formats

Boyanov, M I, Kmetko, J, Shibata, T, Datta, A, Dutta, P, Bunker, B A, and Notre). Mechanism of Pb Adsorption to Fatty Acid Langmuir Monolayers Studied by X-ray Absorption Fine Structure Spectroscopy. United States: N. p., 2010. Web.
Boyanov, M I, Kmetko, J, Shibata, T, Datta, A, Dutta, P, Bunker, B A, & Notre). Mechanism of Pb Adsorption to Fatty Acid Langmuir Monolayers Studied by X-ray Absorption Fine Structure Spectroscopy. United States.
Boyanov, M I, Kmetko, J, Shibata, T, Datta, A, Dutta, P, Bunker, B A, and Notre). 2010. "Mechanism of Pb Adsorption to Fatty Acid Langmuir Monolayers Studied by X-ray Absorption Fine Structure Spectroscopy". United States.
@article{osti_1008792,
title = {Mechanism of Pb Adsorption to Fatty Acid Langmuir Monolayers Studied by X-ray Absorption Fine Structure Spectroscopy},
author = {Boyanov, M I and Kmetko, J and Shibata, T and Datta, A and Dutta, P and Bunker, B A and Notre)},
abstractNote = {The local atomic environment of lead (Pb) adsorbed to a CH{sub 3}(CH{sub 2}){sub 19}COOH Langmuir monolayer was investigated in situ using grazing-incidence X-ray absorption fine structure (GI-XAFS) spectroscopy at the Pb L{sub III} edge. Measurements were performed at pH 6.5 of the 10{sup -5} M PbCl{sub 2} solution subphase, a condition under which grazing incidence diffraction (GID) revealed a large-area commensurate superstructure underneath the close-packed organic monolayer. The XAFS results indicate covalent binding of the Pb cations to the carboxyl headgroups, and the observed Pb-Pb coordination suggests that the metal is adsorbed as a hydrolysis polymer, rather than as individual Pb{sup 2+} ions. The data are consistent with a bidentate chelating mechanism and a one Pb atom to one carboxyl headgroup binding stoichiometry. We discuss how this adsorption model can explain the peculiarities observed with Pb in previous metal-Langmuir monolayer studies. A systematic study of lead perchlorate and lead acetate aqueous solutions is presented and used in the analysis. XAFS multiple scattering effects from alignment of the Pb-C-C atoms in the lead acetate solutions are reported.},
doi = {},
url = {https://www.osti.gov/biblio/1008792}, journal = {J. Phys. Chem. B},
issn = {1520-6106},
number = (36) ; 08, 2003,
volume = 107,
place = {United States},
year = {Thu Sep 30 00:00:00 EDT 2010},
month = {Thu Sep 30 00:00:00 EDT 2010}
}