Sorptive Behavior and Kinetics of Carbendazim in Mineral Soils

studies on adsorption, desorption and reaction kinetics of carbendazim in grey-brown podzolic soil derived from loamy sand (Albic luvisls), grey-brown podzolic soil derived from silt (Haplic luvisols) and brown soil derived from sandy clay loam (Haplic Cambisols) were carried out. Five concentrations of carbendazim (5.0, 3.8, 2.6, 1.0 and 0.2 μg ⋅ cm-3) in 0.01 mol ⋅ dm-3 CaCl2 were used for the 24 h batch adsorption experiments; the desorption experiments were performed by replacing equilibrium solutions with 0.01 mol ⋅ dm-3 CaCl2 and shaking again for the same period of time. The experimental data showed a good fit to the Freundlich equation (r2 in the range 0.988-0.997 for adsorption and 0.980-0.999 for desorption). The values of KF ads varied from 5.45 in the sandy to 11.81 in the loess soil, the KF des from 7.82 in the sandy to 17.87 in the loamy soil; the 1/n values for adsorption and desorption were in the range 0.636-0.812. Adsorption/desorption kinetics were investigated for 1, 2, 4, 6, 8, 10, 24 and 48 h reaction times. The adsorption process in all soils and the desorption process in sandy soil was time-dependent, initially proceeding quickly but within approximately one hour it slowed and ran slowly. useful models for the description of presented experimental kinetic data were the two-site model (r2 in the range 0.727-0.994) and the pseudo second-order model (r2 in the range 0.636-0.988).