Cheap and biodegradable amino acid-based deep eutectic solvents for radioactive iodine capture via halogen bonds

Entrapment of hazardous radioactive iodine has attracted much attention due to the release of radioactive iodine during the application of nuclear energy, such as nuclear waste disposal and nuclear disaster. Deep eutectic solvents (DESs) are deemed as green solvents, designable solvents and solvents of the 21st century. Amino acids are cheap, highly biocompatible and highly biodegradable. Here, we for the first time develop amino acid-based DESs for iodine capture with high efficiency. Effect of structural factors (e.g., mole ratio, composition and composition) and external factors (e.g., mass, concentration and volume of iodine solution) on iodine capture is comprehensively studied. Cysteine:lactic acid (1:8) owns the highest rate and capacity for iodine capture, which shows similar efficiency with previous reports but owns lower cost and higher biodegradability. The high iodine-capturing efficiency of cysteine:lactic acid (1:8) is ascribed to the dominating halogen-bonding interaction (ca. 90%). This work opens a new route for the sustainable capture of radioactive iodine with high efficiency.