Sorptive Interactions of Fungicidal 2-(4'-Thiazolyl) Benzimidazole with Soils of Divergent Physicochemical Composition

Abstract

Thiabendazole, 2-(4'-thiazolyl) Benzimidazole fungicide is rampantly used in Pakistan for controlling fungalgrowth in addition to combating various fungus driven diseases. Thiabendazole leaching and mobility patterns can beeasily predicted through investigation of Thiabendazole adsorption and desorption behavior in soils. Present work iscarried out by conducting a batch equilibration experiment for evaluation of Thiabendazole adsorption and desorption insoils from four diverse Pakistani climatological regions. Data revealed Thiabendazole had moderate to weak adsorption inselected soils with distribution co-efficient Kd(ads) ranging from 13.33 to 24.04 µg/ml in selected soils. The TBZ adsorptionin soils best fitted with Freundlich model (R2>0.87). The Freundlich adsorption coefficient (Kf(ads)) values ranged from4.51 to 8.90 µg/ml. Thiabendazole adsorption trends in the selected soils were positively influenced by the clay contentand soil organic matter while it was negatively influenced by soils’ pH. The Freundlich desorption coefficient (Kf(des))values spanned over a range of 1.03 to 6.43 µg/ml indicating decreased desorption from soils with creditable affinities forThiabendazole adsorption. The adsorptive interactions between Thiabendazole and selected soils were primarily physicalconfirmed through lower values of Gibbs free energy ∆G ≤ - 40kJ/mol. Thiabendazole desorption was highly hysterical inall soils with profound irreversibility. Thiabendazole possessed medium mobility patterns in selected soils. The loweradsorptive capability of Thiabendazole in selected soils points towards its lower application rates for combating long termenvironmentally perilous implications.