Classifying NOM-organic sorbate interactions using compound transfer from an inert solvent to the hydrated sorbent.
Interactions of a wide set of organic compounds with model natural organic matter (NOM, Pahokee peat) were examined using a new approach that converts aqueous sorption to compound transfer from n-hexadecane to the hydrated NOM. This conversion accounts for solute-water interactions and applies the same inert reference medium for all compounds of interest, making it possible to classify sorbates according to the strength of sorbate-NOM interactions. Differences in strength of organic compound interactions in the sorbed phase as great as 4-5 orders of magnitude are demonstrated. The strongest interactions were observed for compounds with well-established H-bonding potentials. Considering hydrocarbons and Cl-substituted hydrocarbons, aliphatic compounds gain more upon distribution from the n-hexadecane medium to NOM than do aromatic compounds. Sorption nonlinearity was tested by comparing the change in n-hexadecane-hydrated NOM distribution coefficient (K(d,i)) versus sorbed concentration for the different compounds. Only those compounds that interact most strongly with NOM demonstrated significant sorption nonlinearity, expressed by a strong reduction in K(d,i) as a function of sorbed concentration. The relationship between compound ability to interact with NOM and reduction in K(d,i) as a function of sorbed concentration can be used to characterize compound distribution among different sorption domains.
Borisover
Mikhail
M
Institute of Soil, Water and Environmental Sciences, The Volcani Center, ARO, Bet Dagan 50250 Israel. vwmichel@volcani.agri.gov.il
Graber
Ellen R
ER
D000327:Adsorption; D006838:Hydrocarbons / Q000032:analysis / Q000737:chemistry*; D008962:Models, Theoretical; D009930:Organic Chemicals; D012995:Solubility; D012997:Solvents / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014873:Water Pollutants / Q000032:analysis*
D006838:Hydrocarbons; D009930:Organic Chemicals; D012997:Solvents; D014873:Water Pollutants; D014867:Water