High toxicity of amino acid-based deep eutectic solvents

Amino acid-based deep eutectic solvents (i.e., ionic liquids analogues (DESs)) have been deemed as green and low toxic materials for efficient CO2 capture, conversion and utilization. However, (1) are amino acid-based DESs really green and low toxic? (2) how to minimize the toxicity of amino acid-based DESs for a better CO2 capture, conversion and utilization? Herein, we for the first time unexpectedly find that amino acid-based DESs are super toxic. The toxicity of amino acid-based DESs could be 105 times that of conventional choline chloride-based DESs, which could be ascribed to the much higher toxicity of DESs than their individuals. The lower toxicity of amino acid-based DESs could be tuned by hydrogen-bonding acceptor, hydrogen-bonding donor, mole ratio and intermolecular interaction. This work would provide a basis for designing less or even no toxic green solvents for better and sustainable CO2 capture, conversion and utilization.