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

Abstract

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 Kd ads and Kd des respectively. Kf ads values ranged from 6.6 to 8µgml-1 whereas values of Kf des followed the range of 1.5µgml-1 to 9.8µgml-1. Most of the samples depict negative hysteresis as their 1/ndes was more than 1/nads. Gibbs or free energy change (∆G) and hysteresis vividly proved physical and reversible adsorption process. The values of K om and Koc 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.

Keywords

• Thiabendazole (TBZ)
• linear isothermal model
• Freundlich isothermal model
• UV-Visible spectrophotometer