Absorption of CO2 may be carried out chemically or physically. Chemical absorption takes advantage of the rapid reaction of CO2 with bases. An alkali absorbent solution, typically that of an amine, is brought into contact with the gas mixture to neutralize CO2 and form carbamate or bicarbonate salts. The resulting solution is then transferred to a regenerator (reboiler) to release the CO2 and recover the solvent. Monoethanolamine (MEA) is the most widely used absorbent and is the only one currently in commercial applications. Other widely studied amines include diethanolamine (DEA), 32 methyldiethanolamine (MDEA), piperazine, and 2-amino-2-methyl-1-propanol (AMP). The latter two are frequently studied as blends with other amines or with each other. Proprietary amine solutions such as Cansolv and Econamine FG Plus have been reported and demonstrated in pilot plants. Amine-based absorptions are effective even for low pressure streams with low CO2 concentrations, making them particularly suitable for postcombustion capture. Their drawbacks include limited thermal and oxidative stability, the high thermal energy required for solvent regeneration, solvent evaporation, and the corrosiveness of the absorbents. The numbers of studies related to CO2 capture using the most popular amines are shown in Given the limited number of commercially available amines suitable as absorbents, additives for amine solutions have been reported with varying success in improving oxidation stability and reducing corrosion. Also, electrochemical solvent regeneration, where CO2 is stripped from the stream by electrochemically generated copper ions, has been reported. The processes were found to be more energy efficient than thermal regeneration, and can be carried out at normal temperatures, thus minimizing solvent loss and thermal degradation.