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Vapor‐phase partitioning of volatile organic compounds: A regression approach
Author(s) -
Thoms Sharon R.,
Lion Leonard W.
Publication year - 1992
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.5620111004
Subject(s) - sorption , chemistry , dissolution , solubility , partition coefficient , aqueous solution , humic acid , water vapor , phase (matter) , hydrogen bond , environmental chemistry , inorganic chemistry , organic chemistry , adsorption , molecule , fertilizer
Partitioning of 15 volatile organic compounds (VOCs) between the vapor phase and dry and moist Al 2 O 3 samples was measured using a headspace technique. The best predictors of partition coefficients ( K ′ p ) from the vapor phase varied with the three Al 2 O 3 moisture contents (MCs) used; these variations may reflect alternate sorption mechanisms. For instance, sorption of chlorinated hydrocarbons at 1.9% MC was best explained by the hydrogen bond acceptor parameter β, suggesting hydrogen bonding between the —Cl group and surface groups or water films. However, sorption on humic acid‐coated Al 2 O 3 at approximately 45% MC was best explained by the log of the aqueous solubility and Henry's law constant. The importance of aqueous solubility and Henry's law constant suggested that dissolution of organic compounds in interstitial water is a primary sorption mechanism for VOCs at high Al 2 O 3 MCs. Sorption of the relatively insoluble hydrocarbons such as n ‐alkanes occurred in excess of that explained by dissolution in the interstitial water and may reflect the importance of partitioning into the organic matter provided by the humic acid coating.