Biodegradability and Ecotoxicity Profiles of Choline Acetate, Betaine, and L-Proline NADESs: A Hidden Threat for Eutrophication?

Deep Eutectic Solvents (DESs), particularly Naturally Available Deep Eutectic Solvents (NADESs), are increasingly regarded as green solvents due to their low vapor pressure, non-flammability, thermal stability, strong solvent power, and low toxicity. In line with Green Chemistry principles, the use of renewable and biocompatible components such as amino acids, lipids, and naturally derived acids enables the development of more sustainable solvent systems. This study addresses the need for environmentally safer NADESs by evaluating their physico-chemical suitability and environmental impact. Fifteen NADESs were prepared using naturally derived components and assessed for environmental safety. Biodegradability was evaluated using the OECD 301D Closed Bottle Test (CBT), while toxicity toward Raphidocelis subcapitata was examined to characterize ecotoxicological behavior. The results demonstrated that the synthesized NADESs exhibit high biodegradability levels and low toxicity toward microalgae. Toxicity control indicated no significant inhibition of microbial activity during biodegradation, suggesting favorable environmental compatibility. Overall, the findings indicate that the NADESs represent more sustainable solvent alternatives with low toxicological profiles. However, the potential role of these compounds in enhancing eutrophication processes cannot be excluded and warrants further investigation.