Determining the adsorption and desorption behavior of thiabendazole fungicide for five different agricultural soils

Thiabendazole 2-(4'-thiazolyl)benzimidazole (TBZ) is a Benzimidazole fungicide. In the present study adsorption and desorption of TBZ was investigated through batch equilibrium method involving UV-Visible spectrophotometer and High-performance liquid chromatography. Linear and Freundlich coefficients and kinetics of TBZ was studied in different agricultural soils of Pakistan. 9.8µgml -1 and 12.09µgml -1 were highest values of K d ads and K d des respectively. K f ads values ranged from 6.6 to 8µgml -1 whereas values of K f des followed the range of 1.5µgml -1 to 9.8µgml -1 . Most of the samples depict negative hysteresis as their 1/n des was more than 1/n ads. Gibbs or free energy change (∆G) and hysteresis vividly proved physical and reversible adsorption process. The values of K om and K oc were indicated medium mobility group of TBZ in selected soils. However all kinetic values varied significantly from sample to sample depending on their physicochemical parameters.