Molecular simulation of a model of dissolved organic matter

Cited 72 time in webofscience Cited 0 time in scopus
  • Hit : 434
  • Download : 0
A series of atomistic simulations was performed to assess the ability of the Schulten dissolved organic matter (DOM) molecule, a well-established model humic molecule, to reproduce the physical and chemical behavior of natural humic substances. The unhydrated DOM molecule had a bulk density value appropriate to humic matter, but its Hildebrand solubility parameter was lower than the range of current experimental estimates. Under hydrated conditions, the DOM molecule went through conformational adjustments that resulted in disruption of intramolecular hydrogen bonds (H-bonds), although few water molecules penetrated the organic interior. The radius of gyration of the hydrated DOM molecule was similar to those measured for aquatic humic substances. To simulate humic materials under aqueous conditions with varying pH levels, carboxyl groups were deprotonated, and hydrated Na(+) or Ca(2+) were added to balance the resulting negative charge. Because of intrusion of the cation hydrates, the model metal-humic structures were more porous, had greater solvent-accessible surface areas, and formed more H-bonds with water than the protonated, hydrated DOM molecule. Relative to Na(+), Ca(2+) was both more strongly bound to carboxylate groups and more fully hydrated. This difference was attributed to the higher charge of the divalent cation. The Ca-DOM hydrate, however, featured fewer H-bonds than the Na-DOM hydrate, perhaps because of the reduced orientational freedom of organic moieties and water molecules imposed by Ca(2+). The present work is, to our knowledge, the first rigorous computational exploration regarding the behavior of a model humic molecule under a range of physical conditions typical of soil and water systems.
Publisher
WILEY-BLACKWELL
Issue Date
2005-08
Language
English
Article Type
Article
Keywords

HUMIC ACIDS; AQUEOUS-SOLUTION; METAL-BINDING; MONTE-CARLO; DYNAMICS; SORPTION; SUBSTANCES; WATER; CLAY; COMPLEXES

Citation

ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY, v.24, no.8, pp.1902 - 1911

ISSN
0730-7268
DOI
10.1897/04-567R.1
URI
http://hdl.handle.net/10203/90697
Appears in Collection
EEW-Journal Papers(저널논문)
Files in This Item
There are no files associated with this item.
This item is cited by other documents in WoS
⊙ Detail Information in WoSⓡ Click to see webofscience_button
⊙ Cited 72 items in WoS Click to see citing articles in records_button

qr_code

  • mendeley

    citeulike


rss_1.0 rss_2.0 atom_1.0