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Calculation of the interaction between dissolved organic carbon and organic micropollutants by three dimensional force field methods
Author(s) -
Govers Harrie A. J.,
van Roon André,
Parsons John R.
Publication year - 2003
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620220412
Subject(s) - dissolved organic carbon , environmental chemistry , field (mathematics) , total organic carbon , carbon fibers , environmental science , organic chemicals , force field (fiction) , chemistry , materials science , computer science , mathematics , composite number , composite material , artificial intelligence , pure mathematics
A 3D optimized potential for liquid simulation (OPLS) force field method with 6–31 G* atomic charges and a geometrical optimization approach was studied for the calculation of enthalpies of transfer at 300 K of partitioning processes. A 3D fulvic acid model of dissolved organic carbon was built. Limonene, α‐pinene, fluoranthene, p,p ′‐DDT, and 2,4‐D were inserted into a general site of preference, and interaction energies were calculated. Energies of hydration were calculated and subtracted from fulvic acid‐contaminant interactions. The resulting values for the enthalpies of transfer from water to dissolved organic carbon were ‐2.2, +0.9, ‐6.4, ‐4.0, and ‐4.3 kcal/mol for limonene, α‐pinene, fluoranthene, p,p ′‐DDT, and 2,4‐D, respectively. This led to a change of the partition constant by a factor of 0.17 to 1.27 at a temperature increase from 5 to 55°C. The values of fluoranthene and p,p ′‐DDT compared favorably with their experimental values of ‐4.4 and ‐5.0 kcal/mol. Prior to this, a general scaling factor for electrostatic interactions in both the pure liquid (s liq = 2.89) and the hydrated solute (s hyd = 3.70) was derived from the experimental values of enthalpies of vaporization and aqueous solution. Resulting predicted enthalpies of vaporization deviated by ‐3.1 (water), 0.4 (limonene), 0.2 (α‐pinene), 3.9 (fluoranthene), ‐3.0 ( p,p ′‐DDT), and 0.9 (2,4‐D) kcal/mol from experimental data, whereas enthalpies of aqueous solution deviated by ‐1.3 (limonene), ‐5.7 (α‐pinene), 4.2 (fluoranthene), and 0.3 ( p,p ′‐DDT) kcal/mol. Results are discussed in terms of molecular structures and their interactions.