Adsorption mechanisms of carbofuran on silica: structure, kinetics, and solubility influence

The adsorption processes of carbofuran from solutions in pure water onto silica (Aerosil 200) have been determined in order to bring greater coherence to previous results obtained directly on soils. Adsorption isotherms and their evolution with temperature reveal that adsorption is generally weak, increases with temperature, and does so significantly with concentration when the solubility limit is approached. Kinetics of dissolving, of adsorption on silica, and of desorption all obey an irreversible two-compartment model. Desorption rate is slower than adsorption rate. Consequences on the behavior of carbofuran in the environment are discussed.