Absorption of carbon dioxide with piperazine and its mixtures in a rotating packed bed

The removal efficiency of carbon dioxide from gases containing 10% CO2 by the aqueous solutions containing piperazine (PZ) and its mixture with monoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP), and methyldiethanolamine (MDEA) in a rotating packed bed was investigated in this study. The efficiency was assessed in terms of an overall volumetric mass transfer coefficient (KGa) that was found to be a strong function of gas and liquid flow rates. The obtained results indicated that PZ was the most effective absorbent over MEA, AMP, and MDEA. This was attributed to a high reaction rate of PZ with CO2. The mixed amines containing PZ and MEA as well as PZ and AMP exhibited a high CO2 removal efficiency as well. A higher portion of PZ in the mixture was more favorable to CO2 absorption. The mixture of PZ with MDEA, however, was found not to be appropriate due to a low reaction activity of MDEA with CO2. The CO2 removal efficiency in a rotating packed bed was also observed to be more effective than that in a packed tower, implying a great potential of a rotating packed bed applied to the reduction of the greenhouse gas CO2 from the exhausted gases.