Enhanced CO2 capture in packed-bed column bioreactors with immobilized carbonic anhydrase

Abstract

• Green CO 2 capture with carbonic anhydrase (CA) immobilized on packing and MNPs. • Novel hybrid enzymatic process in packed-bed column bioreactors. • CA immobilization on MNPs intensifies the CO 2 hydration process. • Enhanced enzymatic CO 2 capture process enables long-term continuous operation. A novel hybrid enzymatic process with human Carbonic Anhydrase II (hCA II) enzyme immobilized on packing surface and magnetic nanoparticles (MNPs) dispersed in liquid absorbent in a gas–liquid packed-bed column bioreactor was proposed. Packing and MNPs surface were amine-functionalized by co-deposition of polydopamine (PDA)/polyethyleneimine (PEI) and hCA II was immobilized on the modified surface via glutaraldehyde. Immobilized hCA II on packing and MNPs displayed a high storage stability even after 40 days, preserving 80% and 84.7% of their initial activities, respectively. CO 2 hydration process achieved significant improvements due to the additional hCA II enzyme immobilized on the MNPs surface, functioning as a free solution-phase enzyme, especially when the diffusion limitation of the enzymatic process with immobilized hCA II enzyme on the packing surface was very significant. CO 2 absorption performance has been evaluated experimentally and theoretically under different conditions, including buffer type, buffer concentration, and operational parameters. A 3-D model describing the hydrodynamics, mass transport/reaction in liquid/gas phases, accumulation of biocatalytic MNPs in packed bed, reaction and diffusion in enzyme washcoat/liquid film was used to investigate the behavior of the packed-bed column bioreactor. Overall, the results achieved in this work illustrated that packed-bed column bioreactor with immobilized CA enzyme on the packing and MNPs surface is an encouraging green CO 2 capture technology design, which improve the utilization of CA enzyme large turnover number.