A hybrid chemo-biocatalytic system of carbonic anhydrase submerged in CO2-phillic sterically hindered amines for enhanced CO2 capture and conversion into carbonates

Abstract

The present study highlights a hybrid approach to capture and convert carbon dioxide (CO2) from exhaust gases using bovine carbonic anhydrase (CA) submerged into aqueous amine solvents. Particularly, the sterically hindered amines have unique properties to absorb CO2 and also play a key role in wide range of industrial applications. In this work, the reaction kinetics of CO2 were studied in the aqueous phase of sterically hindered amines (SHAs), 2-amino-2-hyroxymethyl-1,3-propanediol (AHPD) and 2-amino-2-methyl-1-propanol (AMP), mixed with bovine CA as test and without CA as control using the stopped flow technique. The results showed a significant improvement in the rate of reaction between SHAs (either aqueous AHPD or aqueous AMP) and CO2 in the presence of CA. Moreover, the absorption capacity of SHA for CO2 and its initial absorption rate in presence of CA was significantly enhanced. The rate constants of pseudo first-order reaction of CO2 reacting with AHPD and AMP (each 0.5 kmol/m3) with varied concentration of CA were determined at temperature range of 298- 353 K. The aqueous AHPD and AMP systems in the presence of CA and control retained 65% of absorption capacity after 5 repetitive cycles. Also, the amine solvent captured CO2 was converted into calcium carbonate (CaCO3) which is white powder materials. The synthesized CaCO3 was characterized for its morphological and physicochemical properties using scanning electron microscopy (SEM) and Fourier transformer infrared spectroscopy (FTIR) etc. Overall, as the CA present is the amine solvent can efficiently convert the CO2 and that can be removed easily in the form of CaCO3 precipitates.