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Speciation of uranyl ions in fulvic acid and humic acid: a DFT exploration

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Title Speciation of uranyl ions in fulvic acid and humic acid: a DFT exploration
 
Creator SUNDARARAJAN, M
RAJARAMAN, G
GHOSH, SK
 
Subject SULFATE-REDUCING BACTERIA
ZETA VALENCE QUALITY
GAUSSIAN-BASIS SETS
TRANSITION-ELEMENTS
CORRELATION-ENERGY
CYTOCHROME C(7)
ORGANIC-MATTER
CATION-BINDING
ATOMS LI
DENSITY
 
Description The speciation of uranyl ions in fulvic acid (FA) and humic acid (HA), based on models of larger sizes, is systematically studied using density functional theory (DFT). Four uranyl binding sites are suggested for FA and based on their energetics, the preferential binding sites are proposed. The computed binding sites include two chelating types, one through the carboxylate group and one via the hydroxo group. A systematic way to attain the possible structure for Stevenson's HA model is carried out using a combined molecular dynamics (MD) and quantum chemical approach. Calculated structures and energetics reveal many interesting features such as conformational flexibility of HA and binding of hydrophobic molecules in agreement with the experimental suggestions. Five potential binding sites are proposed for uranyl binding to HA and the calculated geometries correlate nicely with the experimental observations. Our binding energy calculations reveal that apart from uranyl binding at the carboxylate functional group, binding at other functional groups such as those involving quinone and hydroxo sites are also possible. Finally, based on our cluster calculations the strength of uranyl binding to HAs and FAs is largely influenced by neighbouring groups via hydrogen bonding interactions.
 
Publisher ROYAL SOC CHEMISTRY
 
Date 2012-06-26T09:26:48Z
2012-06-26T09:26:48Z
2011
 
Type Article
 
Identifier PHYSICAL CHEMISTRY CHEMICAL PHYSICS,13(40)18038-18046
1463-9076
http://dx.doi.org/10.1039/c1cp21238a
http://dspace.library.iitb.ac.in/jspui/handle/100/14284
 
Language English