Choline [amino acid] ionic liquid/water mixtures: A triple effect for the degradation of an organophosphorus pesticide

Abstract

A series of ionic liquids (ILs) composed by choline (Ch) as a cation and different amino acids (AA) as anions and their respective aqueous mixtures were prepared using different [Ch][AA] contents in a range of 0.4-46 mol % IL. These solvents were used for the first time to achieve an eco-friendlier Paraoxon degradation. The results show that [Ch][AA]/water mixtures are an effective reaction medium to degrade Paraoxon, even when the IL content in the mixture is low (0.4 mol % IL) and without the need of an extra nucleophile. Both the kinetics and the degradation pathways of pesticides depend on the nature of the AA on [Ch][AA] and the amount of an IL present in the mixture. We have demonstrated that in those mixtures with a low amount of [Ch][AA], the hydrolysis reaction is the main pathway for Paraoxon degradation, showing a catalytic effect of the IL. However, as the percentage of [Ch][AA] increases in the mixture, the nucleophilic attack of [Ch][AA] is evident. Finally, the aim of this study was to provide evidence of a promising and biocompatible methodology to degrade a toxic compound (Paraoxon) using a minimal quantity of an IL designed totally from natural resources.