Adsorptive selectivity of organic-cation-modified bentonite for nonionic organic contaminants
- Cite this article as:
- Smith, J.A. & Jaffé, P.R. Water Air Soil Pollut (1994) 72: 205. doi:10.1007/BF01257125
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The mineral surface of Wyoming bentonite was modified by replacing inorganic ions with four quaternary ammonium cations in an amount equal to 40 percent of the cation-exchange capacity of the bentonite. The four quaternary ammonium cations used were tetramethylammonium (TMA), tetraethylammonium (TEA), benzyltrimethylammonium (BTMA), and benzyltriethylammonium (BTEA). Sorption of benzene, tetrachloromethane, trichloroethene, 1,2-dichlorobenzene, and naphthalene to the modified sorbents from water at 20 °C was investigated. All five solutes were sorbed strongly by TEA-, BTMA-, and BTEA-bentonite, but only benzene and tetrachloromethane were strongly sorbed by TMA-bentonite. The sorption isotherms are distinctly nonlinear and the magnitude of sorption is not correlated with the solute's aqueous solubility. In contrast, sorption of trichloroethene, 1,2-dichlorobenzene, and naphthalene to TMA-bentonite was negligible relative to benzene and tetrachloromethane sorption. The apparent absence of solute selectivity by TEA-, BTMA-, and BTEA-bentonite, along with their large sorption capacities, indicates that these sorbents can potentially be useful as components of landfill liners or slurry walls to decrease the mobility of a variety of nonionic organic contaminants.