Adsorption studies on pesticide/cationic surfactant/bentonite systems.

Surfactant-bentonite complexes (organo-clays) with different amounts of adsorbed dodecyltrimethylammonium bromide (DTAB) were prepared. The adsorption of the pesticides paraquat and biphenyl from aqueous solution on clays was studied by the batch method with radiotracers. — On organo-clays the preferentially adsorbed di-cation paraquat only partially replaces the mono-cationic surfactant. This result was supported by investigations with microcalorimetry and x-ray diffraction. — On the contrary, the adsorption of the hydrophobic biphenyl is enhanced with an increased amount of adsorbed DTAB by hydrophobization of the bentonite. [ABSTRACT FROM AUTHOR]