ATRAZINE INTERACTIONS WITH CLAY-MINERALS - KINETICS AND EQUILIBRIA OFSORPTION

A novel technique using on-line microfiltration and HPLC analysis has been used to study sorption kinetics and sorption equilibrium of the h erbicide atrazine with the clay minerals montmorillonite, kaolinite, a nd illite and the clay fraction of a soil. Fast and slow labile sorpti on have been observed for atrazine along with a reversible but kinetic ally slow sorption/desorption process that is consistent with diffusio n of pesticide into the interior of the clay particles. Labile sorptio n capacity, mole fraction site coverage, labile sorption equilibrium f unction, and distribution coefficient were determined for the clay min erals in aqueous slurries with atrazine. The identification and quanti tative descriptions of key chemical species avoid some of the commonly reported hysteresis problems. Distribution coefficients are derived f rom the equilibrium constants so that comparisons may be made with the results of other workers.