Customizable cholinium-based aqueous biphasic systems as ecofriendly extraction platform for removal of pesticide from wastewaters

Abstract

This study explores the use of a series of cholinium ionic liquids (ILs) or salts in combination with polypropylene glycol 400 to form aqueous biphasic systems (ABS) for extracting various polarity pesticides (dicamba, clomazone, pyraclostrobin, and deltamethrin) from water. We assessed five cholinium-based salting-out agents ([Ch][DHP], [Ch]Cl, [Ch][Ac], [Ch][Lac], and [Ch][Nic]), chosen for their structural diversity and unique properties, such as high salting-out potential and different ability to undergo specific interactions. Liquid-liquid equilibrium phase diagrams were established, and partition experiments were conducted to evaluate extraction efficiency. Different partition patterns were obtained for studied pesticides, with [Ch][DHP] demonstrating the highest efficiency exceeding 90 % for each target pesticide due to its strong salting-out ability. On the other hand, more diverse partition trends due to specific interactions were obtained for low-melting cholinium-ILs ABS. The effect of pH and temperature on the partitioning behavior in [Ch][Ac]-based ABS highlighted the cholinium ILs extraction system's customizable nature. Focusing on [Ch]Cl for its eco-friendly aspects, widespread availability and excellent extraction performance, we optimized parameters for the removal of pesticides from real samples, applying the technology to spiked agricultural wastewater with an extraction efficiency of over 99 %. Our findings demonstrate the potential of cholinium-based IL-ABS in reducing environmental pollution through efficient pesticide extraction.