Utilization of Deep Eutectic Solvents to Reduce the Release of Hazardous Gases to the Atmosphere: A Critical Review.

The release of certain gases to the atmosphere is controlled in many countries owing to their negative impact on the environment and human health. These gases include carbon dioxide (CO), sulfur oxides (SOx), nitrogen oxides (NOx), hydrogen sulfide (HS) and ammonia (NH). Considering the major contribution of greenhouse gases to global warming and climate change, mitigation of these gases is one of the world's primary challenges. Nevertheless, the commercial processes used to capture these gases suffer from several drawbacks, including the use of volatile solvents, generation of hazardous byproducts, and high-energy demand. Research in green chemistry has resulted in the synthesis of potentially green solvents that are non-toxic, efficient, and environmentally friendly. Deep eutectic solvents (DESs) are novel solvents that upon wise choice of their constituents can be green and tunable with high biocompatibility, high degradability, and low cost. Consequently, the capture of toxic gases by DESs is promising and environmentally friendly and has attracted much attention during the last decade. Here, we review recent results on capture of these gases using different types of DESs. The effect of different parameters, such as chemical structure, molar ratio, temperature, and pressure, on capture efficiency is discussed.