Investigation of the kinetics of imidacloprid adsorption onto bimetallic Cu-BTC MOF

Imidacloprid, which is harmful for humans as well as many other aquatic invertebrate species, is extensively present in water worldwide. Hydrophobic Cu-BTC_IPA and a novel composite, Ag@Cu-BTC_IPA was synthesized for adsorption of imidacloprid from water. The synthesis of the composite and the increase in surface area and pore volume were confirmed by FTIR, XRD, SEM, and BET analysis. A comparative study of the adsorption efficiencies of the synthesized composites was performed. The maximum adsorption efficiency achieved was 83.6 % at pH 7 by the Ag@Cu-BTC_IPA composite. Kinetic and isotherm analyses suggested multilayer chemisorption involving p-p conjugation and pore-filling mechanisms. Intra-particle diffusion was the rate limiting step. Release studies of imidacloprid from water showed that the percentage release amount was 90.2 % at 70 min. Kinetic analysis of the release process suggested release through chemisorption, with swelling-controlled release from the dosage form, corresponding to the super case II transport mechanism.