Accelerated carbonate weathering by immobilized recombinant carbonic anhydrase

CO2 absorption in aqueous alkaline solutions promoted by carbonic anhydrase (CA) has received increased attention as a solution for post-combustion CO2 capture. In particular, accelerated weathering has emerged as an alternative approach for CO2 capture, mimicking nature’s way to sequestrate CO2. In this study, an evolved CA from Desulfovibrio vulgaris was immobilized on magnetic nanoparticles (MNPs) offering a promising solution for the effective enzyme separation and recovery from complex and heterogeneous reaction media. The immobilization yields were high (86–98 %) and MNPs-DvCA8.0 were characterized based on standardized CO2 release and CO2 absorption assays and compared to the free enzyme. As a following step, MNPs-DvCA8.0 were applied as promoter in the accelerated weathering of insoluble lime mud, originating as a residue from a paper and pulp industry. MNPs-DvCA8.0 could be efficiently separated, washed and reused for up to 10 consecutive reaction cycles, offering a biocatalyst productivity equal to 2.83 g captured CO2/g CA opposite to the free enzyme that offered only 1.01 g captured CO2/g CA. CA immobilization could offer a mitigation strategy for the non-selective adsorption of the free enzyme on lime mud particles during the CO2 capturing reaction. The highly reproducible and robust immobilization method, that provides material separation based on its magnetic properties, could be a viable solution for the recovery of enzyme and its separation from the lime mud slurry, aiding in obtaining a highly pure solution rich in bicarbonate, as product.