Immobilization of carbonic anhydrase for biomimetic CO2 capture in a slurry absorber as cross-linked enzyme aggregates (CLEA)

Novel post-combustion Carbon Capture and Storage (CCS) processes include absorption of CO2 into aqueous solutions assisted by enzyme catalysis. Carbonic anhydrase EC 4.2.1.1 (CA) catalyzes CO2 hydration and it has been proposed as industrial biocatalyst for biomimetic CCS processes. The present study reports on the use of bovine CA immobilized via cross-linking of enzyme aggregates (CLEA). The aim of this study was to improve the biocatalyst stability at the typical operating conditions of CCS processes (high temperature, alkaline pH, high salt concentration). The optimum conditions of the immobilization procedure were determined in terms of enzyme concentration and cross-linker concentration. In addition, a magnetic CLEA (m-CLEA) sample was prepared, based on cross-linking in presence of amino-functionalized paramagnetic nanoparticles. Immobilization yields was remarkable in both cases. No substantial differences were observed between conventional and magnetic CLEA. The use of magnetic CLEA enables effective separation of the biocatalyst from the reaction mixture and prevent drawbacks associated with CLEA aggregation and compaction induced by centrifugation and filtration.