Hybrid enzymatic CO2 capture process in intensified flat sheet membrane contactors with immobilized carbonic anhydrase

Abstract

A hybrid enzymatic CO2 absorption process in an intensified flat sheet membrane contactor with immobilized human carbonic anhydrase II (hCA II) enzyme was proposed. In addition to be immobilized on the membrane surface, extra carbonic anhydrase enzyme was immobilized on the surface of magnetic nanoparticles (MNPs) dispersed in the liquid phase to reduce the mass transfer limitations and enhance the absorption process. This hybrid enzymatic process is beneficial to attain high CO2 absorption rates, even if a component of the enzymatic system, either the biocatalytic membrane or biocatalytic MNPs, does not operate appropriately. The improvement CO2 hydration in the presence of biocatalytic MNPs was more significant at lower CA loadings on membrane surface. Reusability of the biocatalytic membranes and biocatalytic MNPs was demonstrated by 10 absorption cycles and the intensified membrane contactor displayed stable operation for several hours. A multiscale mathematical model (under gas-filled or partially liquid-filled membrane pores conditions) was proposed to explore the behaviour of the intensified membrane contactor. Model simulations showed that the resistance to mass transfer in membrane wetted zones is overcame by the CO2 enzymatic absorption in these zones (catalyzed by enzyme immobilized in membrane pores) and possible by the absorption of CO2 in the presence of biocatalytic MNPs.