Adsorption-Desorption Behaviour of Pyridalyl on Clays

The study reports the adsorption-desorption of pyridalyl on three clays. Clays showed very high adsorption of pyridalyl and the Freundlich adsorption coefficient (K_f) values for pyridalyl on kaolinite, montmorillonite and nano-bentonite were 885.1, 4360.1 and 6031.1, respectively. Thus, nano-bentonite clay showed maximum pyridalyl adsorption followed by montmorillonite and kaolinite. Pyridalyl sorption in clay showed positive correlation with cation exchange capacity of clays while negative correlation was observed with clay particle size. Desorption of pyridalyl from clays followed the order: montmorillonite > nano-bentonite > kaolinite. Thus, nano-bentonite, which showed maximum pyridalyl adsorption, did not retain maximum amount of sorbed insecticide. The K_f desorption coefficient for pyridalyl in montmorillonite clay was 10 times higher than that in nano-bentonite clay. The study suggested that clays can play a significant role in environmental behaviour of pyridalyl.