Sorption of Aromatic Compounds to Clay Mineral and Model Humic Substance-Clay Complex: Effects of Solute Structure and Exchangeable Cation
- 1 May 2008
- journal article
- Published by Wiley in Journal of Environmental Quality
- Vol. 37 (3), 817-823
- https://doi.org/10.2134/jeq2007.0217
Abstract
Clay minerals and humic substance (HS)-clay complexes are widely distributed in soil environments. Improved predictions on the uptake of organic pollutants by soil require a better understanding of fundamental mechanisms that control the relative contribution from organic and inorganic constituents. Five selected aromatic compounds varying in electronic structure, including nonpolar phenanthrene (PHEN), 1,2,4,5-tetrachlorobenzene (TeCB), polar 1,3-dinitrobenzene (DNB), 2,6-dichlorobenzonitrile (dichlobenil [DNL]), and 1-naphthalenyl methylcarbamate (carbaryl [CBL]), were sorbed separately from aqueous solution to Na(+)-, K(+)-, Cs(+)-, and Ca(2+)-saturated montmorillonites with and without the presence of dissolved HS at pH about 6. Upon normalizing for hydrophobic effects by solute aqueous solubility, the overall trend of sorptive affinity to HS-free K(+)-clay is DNB >> DNL, CBL > PHEN, TeCB, indicating preferential adsorption of the polar solutes. With the presence of HS, sorption of PHEN, TeCB, and CBL increases by several times compared with the pure clay, attributed to HS-facilitated hydrophobic partition (PHEN and TeCB) or H-bonding (CBL). The enhanced sorption of PHEN by HS is cation dependent, where Cs(+) shows the strongest facilitative effect. Coadsorption of HS does not affect sorption of DNB and DNL to clays except that of DNB to Ca(2+)-clay because cation-dipole interactions between the polar group (NO(2) or CN) of solute and weakly hydrated exchangeable cations dominate the overall sorption.Keywords
Funding Information
- China National Science Foundation (20637030, 20647002)
- Jiangsu Province Science Foundation (BK2006128)
This publication has 39 references indexed in Scilit:
- The role of mineral and organic components in phenanthrene and dibenzofuran sorption by soilEuropean Journal of Soil Science, 2005
- Cation–π Bonding: A New Perspective on the Sorption of Polycyclic Aromatic Hydrocarbons to Mineral SurfacesJournal of Environmental Quality, 2004
- Characterization of NOM adsorption to clay minerals by size exclusion chromatographyWater Research, 2000
- Mechanisms for adsorption of organic bases on hydrated smectite surfacesEnvironmental Toxicology and Chemistry, 1999
- Sorption of 2,4-Dichlorophenoxyacetic Acid by Model Particles Simulating Naturally Occurring Soil ColloidsEnvironmental Science & Technology, 1999
- The Sorption of Pyrene and Anthracene to Humic Acid‐Mineral Complexes: Effect of Fractional Organic Carbon ContentJournal of Environmental Quality, 1997
- Specific Adsorption of Nitroaromatic Explosives and Pesticides to Clay MineralsEnvironmental Science & Technology, 1996
- Partition equilibriums of nonionic organic compounds between soil organic matter and waterEnvironmental Science & Technology, 1983
- Sorption of polynuclear aromatic hydrocarbons by sediments and soilsEnvironmental Science & Technology, 1980
- Sorption of hydrophobic pollutants on natural sedimentsWater Research, 1979