Ecotoxicity of Pyridinium Based ILs towards Guppy Fish and Four Bacterial Strains

Abstract

Ionic liquids (ILs) are molten salts that possess low melting points and wide solvation properties. ILs attracted the attention of the academic and industrial professionals due remarkable properties such as low vapor pressure and thermal stability which make them more environmentally friendly as they can replace volatile organic solvents (VOCs) in many organic reactions. This has brought attention to broaden this research area to overcome the harmful emissions from VOCs in industry. Pyridinium ILs have a wide range of applications in various domains such as material sciences, organic and bioorganic syntheses, biotechnologies, nanotechnology and Enhanced Oil Recovery (EOR). However, available toxicity data in literature is yet scarce and hampers a large scale development. In this study, 18 synthesized ILs were tested against guppy fish and four bacterial strains. Two gram negative bacteria: Salmonella enterica, Vibrio cholera and two gram positive bacteria: Listeria monocytogenes, Staphylococcus aureus were chosen to represent each category of bacteria. Fish test was conducted using OECD guidelines and the “96-well plate” procedure was adopted for the bacterial test using (CLSI M100-S24). Results showed that long alkyl chain length ILs showed higher toxicity than short alkyl chain analogs on all the targeted strains. The highest toxic effect exhibited by pyridinium ILs towards guppy fish was moderately toxic and the rest varied between relatively harmless and practically nontoxic. The highest antibacterial effect indicated slightly toxic effect towards Staphylococcus aureus obtaining EC50 = 19.3mg/L. In most cases, pyridinium ILs indicated relatively harmless and practically harmless effects towards bacteria after comparing the EC50 values obtained with Passino and Smith 1987 hazard ranking.