The CO2 absorption-desorption performance of non-aqueous solutions comprising a sterically hindered amine system (2-amino-2-ethyl-1,3-propanediol (AEPD): 1-hexanol) was investigated in a gas-liquid stirred cell reactor under sequential absorption-desorption cycles. The absorption capacity and initial absorption rate were calculated for different concentrations of AEPD: 1-hexanol at 303 K and 2 bar absolute pressure. Increasing the amount of AEPD increased the CO2 absorption capacity. The biocatalytic effect of a constant amount of carbonic anhydrase (CA) on the CO2 absorption performance was also investigated, and the CA enzyme was found to increase the total amount of absorbed CO2. The CO2 loading of AEPD: 1-hexanol and CA activated AEPD: 1-hexanol were 0.88 and 0.97 mol CO2/mol AEPD, respectively. CO2 desorption experiments were performed in different sequences of the same experimental set-up at 363 K and 1.1 bar absolute N2 pressure. The effect of ultrasonic irradiation on the desorption performance of 0.1 g/L CA catalyzed AEPD: 1-hexanol system was also investigated. It was observed that ultrasonic assistance shortened the desorption time and enhanced the desorption rate. Furthermore, the effectiveness of regeneration, the reusability, and performance loss of AEPD: 1-hexanol, in the presence and absence of CA, were analyzed by Fourier transform infrared spectrometry.
CO2 capture, Carbonic anhydrase, FTIR, Sterically hindered amines