Ecotoxicity assessment of dicationic versus monocationic ionic liquids as a more environmentally friendly alternative

Abstract

One of the reasons why ionic liquids have received growing interest from researchers is their environmentally interesting characteristics, such as their negligible vapour pressure and their good chemical and thermal properties. In particular, dicationic ionic liquids whose thermal and electrochemical stability is higher than that of monocationic ionic liquids have begun to gain attention during recent years. In this work, monocationic and dicationic ionic liquids were synthesized, characterized and tested for their toxicity, which was assessed using the luminescent bacterium Vibrio fischeri. The results revealed that the toxicity of the ionic liquids mainly depends on the head groups and linkage chain length of their cationic structure. Introduction of a new cationic head decreased the EC (concentration which leads to 50% reduction in bioluminescence of the bacteria) of the ionic liquids. The results present a promising picture of dicationic ionic liquids as alternatives with lower environmental impact than their monocationic counterparts and underline the significance of designing particular structures for ionic liquids.

Ecotoxicity evaluation towards Vibrio fischeri of imidazolium- and pyridinium-based ionic liquids for their use in separation processes

“…Table 2 also shows the octanol-water partition coefficients estimated from the Eq. 1, proposed by Montalbán et al [36]: , has the lowest toxicity among all the studied ILs, which is in good agreement with previous studies [37,38]. It is interesting to highlight that the effect of the anion on the toxicity decreases with longer cation alkyl chains.…”

An insight into the intermolecular vibrational modes of dicationic ionic liquids through far-infrared spectroscopy and DFT calculations

“…A few works indicated that DILs behave in a different way from the structurally related MILs when tested in the same application. For instance, it has been found that some DILs are characterized by lower polarity and different structural organizations, 21 higher thermal stabilities, 22 lower ecotoxicities, 23 higher activity in the cycloaddition of CO 2 to epoxides, 24 higher or lower cathodic reductions, depending on the type of spacer. 25 The physico-chemical properties of ILs, and accordingly their potential applications, are strictly governed by the type and strength of the interaction between the constituent ions.…”

An Overview on the Toxicological Properties of Ionic Liquids toward Microorganisms

“…The structure and orientation of cations are key factors that determine membrane interactions and concurrent toxicity to different microorganisms. While an increase in the cationic side chain length of an IL is directly related to an increase in membrane activity, the orientation of the cationic group emerges as a structural and biological element that must be considered in ILs toxicity . The most amino acid ILs (AAILs) were found to be nontoxic with no inhibition zone against target bacteria, while some AAILs demonstrated low toxicity even at high concentrations (1 mol L −1 ) .…”

“…They have remarkable features that can be easily custom‐made by a plethora of cations and anions, making them task‐specific solvents and agents. Because of these tailor‐made properties, ILs have been used in a wide variety of applications including biotechnology, chemical engineering, separation processes, material sciences, green chemistry, pharmaceutics, and many others. The use of ILs in biological applications has gained popularity in recent years because ILs are less toxic than that of many conventional organic solvents.…”