Design of deep eutectic solvent for efficient I2 and CO2 capture

As industrial and economic activities continue to expand, the emissions of polluting gases remain a significant threat to the environment and human health. In the energy sector, for instance, nuclear plants produce radioactive iodine isotopes (129I and 131I) during uranium-235 fission, with volatile and harmful I2 vapours requiring effective containment. Similarly, fossil fuel-based industries emit large quantities of CO2, a major greenhouse gas responsible for global warming and climate change. Developing sustainable, reversible, and cost-effective strategies for I2 and CO2 capture is therefore essential. In this context, deep eutectic solvents (DESs) have attracted considerable attention in recent years due to their simpler synthesis, environmental benignity, and cost-effectiveness. In this contribution, we present various cholinium-glycerol DESs with exceptional iodine uptake efficiency of up to 400 ms%, outperforming several benchmark porous absorbents. By combining Raman spectroscopy and thermal gravimetric analysis (TGA), we identified the species formed and transformed during the uptake and release of iodine, underlining the role of halogen bonding. Beyond iodine, we further explored amine-based DES and DES-like systems to enhance CO₂ capture while minimizing the solvent loss commonly observed in pure amines. Absorption experiments demonstrated higher specific capacities, while TGA highlighted a remarkable reduction in evaporation, especially in the n-butylamine/glycerol mixture, likely stabilized by an extended hydrogen-bond network. Together, these findings highlight DESs as a sustainable and multifunctional tool for addressing diverse industrial gas pollutants, bridging challenges from nuclear safety to carbon mitigation.