INTERACTION OF CHLORDIMEFORM WITH CLAY MINERALS

Abstract--The adsorption-desorption of the cationic pesticide chlordimeform from aqueous olutions on montmorillonite, kaolinite, illite, and vermiculite appears to be a cation-exchange process coupled with the coadsorption f neutral molecules and the extraction ofAI from the structure of the mineral. Chlordimeform adsorption on montmorillonite, illite, and vermiculite by cation exchange isan irreversible process, where-as chlordimeform adsorbed on kaolinite is weakly bonded to the clay and easily removed by washing with water. X-ray powder diffraction and infrared spectroscopic data show that chlordimeform cations are ad-sorbed in the interlamellar spaces of montmorillonite at charge sites, lying in a fiat position in contrast to kaolinite, illite, and vermiculite, where they adsorb on external surfaces or charge sites close to the crystal edges