Efficient iodine capture by biocompatible PEG-based deep eutectic solvents: Kinetics and dynamic mechanism

Capture of radioactive iodine has been paid much attention due to the release of radioactive iodine from nuclear accident and metal fission. Deep eutectic solvents (DESs) are green solvents. Polyethylene glycol (PEG) possesses the merits of no toxicity, high biocompatibility, high biodegradation and low cost. Here, we for the first time design a series of PEG-based DESs for efficient iodine capture. PEG:thiourea+ethanol mixture owns the highest rate and capacity for iodine capture. Effect of mass, mol ratio, organic solvent, molecular weight of PEG and composition of DESs on iodine capture is investigated. W = W-infinity(1 - e-(kx)) is first fitted for DESs to capture iodine. Conventional, difference and the PCMW2D-COS UV-Vis spectra show that PEG:thiourea+ethanol interacts with iodine mainly via halogen bonds before 75 min and via induced force after 75 min. The iodine-capturing rate by PEG:thiourea+ethanol is slightly higher than that of the reported DESs with the highest efficiency while in the same condition. Although the presence of volatile ethanol in PEG:thiourea decreases the iodine storage efficiency, it would provide a new route of improving iodine-capturing rate and capacity. (C) 2019 Elsevier B.V. All rights reserved.