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Characterization of technical grade carbonic anhydrase as biocatalyst for CO 2 capture in potassium carbonate solutions
Author(s) -
Peirce Sara,
Perfetto Rosa,
Russo Maria Elena,
Capasso Clemente,
Rossi Mosè,
Salatino Piero,
Marzocchella Antonio
Publication year - 2018
Publication title -
greenhouse gases: science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.45
H-Index - 32
ISSN - 2152-3878
DOI - 10.1002/ghg.1738
Subject(s) - chemistry , potassium carbonate , carbonic anhydrase , bicarbonate , carbonate , solvent , catalysis , absorption (acoustics) , inorganic chemistry , biocatalysis , nuclear chemistry , organic chemistry , enzyme , reaction mechanism , materials science , composite material
Reactive absorption promoted by carbonic anhydrase (CA, E.C. 4.2.1.1.) catalysis has been proposed for CO 2 capture from exhaust gas as an alternative to the reactive absorption in amine solutions. Potassium carbonate solutions allow feasible CO 2 capture assisted by CA. This paper reports on the characterization of a CA form supplied by Novozymes as a catalyst for CO 2 capture in K 2 CO 3 solutions at operating conditions relevant for industrial processes (2–3 M K 2 CO 3 , 298–313 K, 0–40% carbonate to bicarbonate conversion). CO 2 absorption tests were carried out in a batch‐stirred cell apparatus at constant gas volume and temperature by measuring gas pressure decay. The enhancement ratio between CO 2 absorption rate with and without the enzyme at biocatalyst concentration above 0.3 kg m −3 ranged between 5 and 8 depending on the solvent composition and temperature. Active enzyme aggregates formed at protein concentration larger than 0.3 kg/m 3 and their contribution to the absorption rate enhancement was remarkable. Assessment of enzyme kinetics in homogeneous solutions at enzyme concentration lower than 0.018 kg·m −3 showed that k cat /K M increased with both temperature and salt concentration. k cat /K M ranged between 9.0·10 3 and 7.0·10 4 m 3 ·kg −1 ·s −1 in agreement with literature data on carbonic anhydrase kinetics. Reliability of the adopted method for kinetic characterization was confirmed. The activity of enzyme aggregates formed in the carbonate solvent was verified and CA aggregates can be used to select the proper CA based biocatalyst for CO 2 capture application as an alternative to free and immobilized enzyme. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.