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Linear adsorption of nonionic organic compounds from water onto hydrophilic minerals: Silica and alumina

Environmental Science and Technology

By:
, , ,
DOI: 10.1021/es0609809

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Abstract

To characterize the linear adsorption phenomena in aqueous nonionic organic solute-mineral systems, the adsorption isotherms of some low-molecular- weightnonpolar nonionic solutes (1,2,3-trichlorobenzene, lindane, phenanthrene, and pyrene) and polar nonionic solutes (1,3-dinitrobenzene and 2,4-dinitrotoluene) from single-and binary-solute solutions on hydrophilic silica and alumina were established. Toward this objective, the influences of temperature, ionic strength, and pH on adsorption were also determined. It is found that linear adsorption exhibits low exothermic heats and practically no adsorptive competition. The solute-solid configuration and the adsorptive force consistent with these effects were hypothesized. For nonpolar solutes, the adsorption occurs presumably by London (dispersion) forces onto a water film above the mineral surface. For polar solutes, the adsorption is also assisted by polar-group interactions. The reduced adsorptive forces of solutes with hydrophilic minerals due to physical separation by the water film and the low fractions of the water-film surface covered by solutes offer a theoretical basis for linear solute adsorption, low exothermic heats, and no adsorptive competition. The postulated adsorptive forces are supported by observations that ionic strength or pH poses no effect on the adsorption of nonpolar solutes while it exhibits a significant effect on the uptake of polar solutes. ?? 2006 American Chemical Society.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Linear adsorption of nonionic organic compounds from water onto hydrophilic minerals: Silica and alumina
Series title:
Environmental Science and Technology
DOI:
10.1021/es0609809
Volume
40
Issue:
22
Year Published:
2006
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
6949
Last page:
6954
Number of Pages:
6