Supported Ionic Liquids materials to remove insecticides

Abstract

Neonicotinoids insecticides are generally used to control pests in agriculture and for veterinary applications.1,2 Due to their extensive use, these compounds can be found in various environmental compartments, such as water, soils, and biota, which can be a problem of concern due to their toxicity against non-target organisms.2 Given this, it is of utmost priority to develop innovative and effective strategies able to remove neonicotinoids, while preventing environmental contamination by their exposure. In this work, supported ionic liquids (SILs) were studied as alternative adsorbent materials to remove insecticides, namely imidacloprid, acetamiprid, thiacloprid, and thiamethoxam, from aqueous matrices. SILs were initially synthesized and characterized and then employed in adsorption studies. The best identified SIL for the adsorption of all neonicotinoids was silica modified with propyltrioctylammonium chloride, [Si][N3888]Cl. The saturation of the materials was attained in 5 min or less, demonstrating their fast adsorption rate for the target compounds. The best fitting of the experimental kinetic data was achieved with the Pseudo Second-Order model, suggesting that the adsorption process is controlled at the solid-liquid interface, whereas for the experimental isotherm data Freundlich isotherm model was considered the best, exposing the occurrence of multiple layers of insecticides onto the surface of the material. The removal efficiency under continuous mode through solid-phase extraction using [Si][N3888]Cl was also evaluated, with maximum adsorption capacities decreasing according to the following order: imidacloprid > thiacloprid > thiamethoxam > acetamiprid. Overall, it was probed the outstanding adsorption performance of SILs for a wide range of insecticides, confirming their potential to be used as adsorbent materials to remove these compounds from aqueous matrices. This will contribute to avoid their introduction in the environment and therefore reduce all the associated environmental and health burdens.