Ja. Smith et Pr. Jaffe, ADSORPTIVE SELECTIVITY OF ORGANIC-CATION-MODIFIED BENTONITE FOR NONIONIC ORGANIC CONTAMINANTS, Water, air and soil pollution, 72(1-4), 1994, pp. 205-211
The mineral surface of Wyoming bentonite was modified by replacing ino
rganic ions with four quaternary ammonium cations in an amount equal t
o 40 percent of the cation-exchange capacity of the bentonite. The fou
r quaternary ammonium cations used were tetramethylammonium (TMA), tet
raethylammonium (TEA), benzyltrimethylammonium (BTMA), and benzyltriet
hylammonium (BTEA). Sorption of benzene, tetrachloromethane, trichloro
ethene, 1, 2-dichlorobenzene, and naphthalene to the modified sorbents
from water at 20 degrees C was investigated. All five solutes were so
rbed strongly by TEA-, BTMA-, and BTEA-bentonite, but only benzene and
tetrachloromethane were strongly sorbed by TMA-bentonite. The sorptio
n isotherms are distinctly nonlinear and the magnitude of sorption is
not correlated with the solute's aqueous solubility. In contrast, sorp
tion of trichloroethene, 1, 2-dichlorobenzene, and naphthalene to TMA-
bentonite was negligible relative to benzene and tetrachloromethane so
rption. 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 landfi
ll liners or slurry walls to decrease the mobility of a variety of non
ionic organic contaminants.