Document Detail

Distribution of proton dissociation constants for model humic and fulvic acid molecules.
MedLine Citation:
PMID:  19544864     Owner:  NLM     Status:  MEDLINE    
The intrinsic proton binding constants of 10 model humic acid and six model fulvic acid molecules are calculated using SPARC Performs Automated Reasoning in Chemistry (SPARC). The accuracy of the SPARC calculations is examined using estimated microscopic binding constants of various small organic acids. An equimolar mixture of the appropriate hypothetical molecules is used as a representation of soil and aqueous humic acid and fulvic acid. The probability distributions of the mixture microscopic proton binding constants and the intrinsic proton binding constants in the metal speciation models WHAM V and WHAM VI (Windermere humic aqueous models) are compared. The idea is to assess the predictive value of the molecular mixture models as representations of heterogeneous natural organic matter. For aqueous humic and fulvic acids, the results are comparable to the WHAM distribution. For soil humic acid, the WHAM probability distribution is less acidic for the carboxylic sites but similar to that of the phenolic sites. Computations made using the WHAM molecular distributions and WHAM VI are comparable to titration data for Suwannee River fulvic acid. These results suggest that mixture molecular models can be used to investigate and predict the binding of metal cations to humic and fulvic acids.
Yasemin B Atalay; Richard F Carbonaro; Dominic M Di Toro
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Environmental science & technology     Volume:  43     ISSN:  0013-936X     ISO Abbreviation:  Environ. Sci. Technol.     Publication Date:  2009 May 
Date Detail:
Created Date:  2009-06-23     Completed Date:  2009-07-20     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3626-31     Citation Subset:  IM    
Department of Civil & Environmental Engineering, University of Delaware, Newark, Delaware 19716, USA.
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MeSH Terms
Benzopyrans / chemistry*
Humic Substances / analysis*
Models, Molecular*
Reproducibility of Results
Rivers / chemistry
Grant Support
Reg. No./Substance:
0/Benzopyrans; 0/Humic Substances; 0/Protons; 479-66-3/fulvic acid

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