Adsorption-desorption of atrazine on vertisols and alfisols

Adsorption-desorption of atrazine was measured in four soils of Hyderabad using batch equilibrium method at 27±1°C. The Freundlich equation was used to describe batch results. Both adsorption and desorption isotherms were well described by the Freundlich model. Fitted K_f value for desorption isotherms were consistently higher than those associated with adsorption. The opposite trend was observed for the exponential parameter n. The results revealed that the desorption data deviated significantly from adsorption data. The deviation, which is commonly referred to as hysteresis, was more prominent with higher adsorbed concentration of atrazine and incubation time. Desorption was significantly higher at the lowest adsorbed level of atrazine. The Freundlich K_f and n values were higher than that for adsorption and increased with increase in initially adsorbed concentration of atrazine.