Development of hydrophobic deep eutectic solvents for extraction of pesticides from aqueous environments

Wastewater treatment plants do not properly address the removal of emerging micropollutants, such as pesticides, and thus these compounds contaminate water sources of public drinking water systems. In this context, this work focuses on the development of hydrophobic deep eutectic solvents (DESs), as cheap extractants for the removal of four neonicotinoids, Imidacloprid, Acetamiprid, Nitenpyram and Thiamethoxam, from diluted aqueous solutions. In particular, two different families of DESs, one based on natural neutral ingredients (DL-Menthol and natural organic acids) and the other based on quaternary ammonium salts and organic acids were prepared and their water stability carefully studied through H-1 NMR. Only the chemically stable DESs were selected to be used as solvents in the extraction of the four neonicotinoids so that no contamination of the water cycle is attained, while reuse of the DES is possible. The final results were compared with those obtained for liquid-liquid extraction using hydrophobic imidazolium-based ionic liquids as solvents. (C) 2017 Elsevier B.V. All rights reserved.