Environmental impact assessment of dicationic ionic liquids with ammonium-phosphonium cations and amino acid anions

Abstract

Progress in the development of biodegradable or biobased ionic liquids (ILs) has led to the design of green compounds for several applications. Herein, four biocompatible dicationic ionic liquids (DILs) with ammonium-phosphonium cations and amino acid anions were synthesized and investigated their environmental impact. The structures of the DILs were confirmed by spectral analyses (1H, 13C and 31P NMR). Furthermore, physicochemical properties such as density, viscosity and refractive index were determined. Water content, bromide content and solubility were thereafter determined as the parameters needed for further studies. Subsequently, their antifeedant activity towards economically important pests of grain in storage warehouses: the granary weevil, confused flour beetle, and the khapra beetle was examined, showing the dependence on structure. Moreover, selected DILs were investigated for toxicity towards white mustard, Daphnia magna, and Artemia franciscana to specify the environmental impact. These studies were complemented by understand the biodegradation of DILs by bacterial communities derived from soil at the agricultural land. The result was DILs with limited environmental footprints that have great potential for further application studies. Ionic liquids, despite numerous reports highlighting their high application potential, elicit environmental concerns. Scientist indicated some of them low biodegradability, adverse effects on plant and insect growth, and toxicity to freshwater and saltwater organisms. This study endeavors to design ammonium-phosphonium ionic liquids (dicationic ionic liquids) with minimal negative impacts on terrestrial and aquatic ecosystems. Additionally, amino acids were employed in their synthesis to achieve above objectives, and a less harmful method for synthesizing the ammonium-phosphonium cation was developed.

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