Immobilization of carbonic anhydrase in alginate and its influence on transformation of CO2 to calcite

► Carbonic anhydrase (CA) has been immobilized by entrapment into alginate beads. ► Physicochemical properties of CA related to CO2 sequestration have been studied. ► CO2 sequestration into calcite has been achieved via CA catalyzed reactions. ► XRD and SEM analysis confirms the formation of calcite. Present investigation entails carbonic anhydrase (CA) immobilization and its influence on transformation of CO2 to calcite. CA enzyme was immobilized in alginate beads, subsequently maintained its catalytic efficiency after sequential operational cycles. The immobilized beads showed better operational stability by retaining nearly 67% of its initial activity even after six cycles. Batch scale studies with free and immobilized enzyme revealed that the entrapped CA hydrates CO2 to bicarbonate and/or carbonate which was then made to react with Ca2+ ions to transform into calcite. Calcite was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The entrapped CA was employed for the performance evaluation with respect to several operational parameters including the influence of enzyme concentration in free and immobilized condition. It was concluded that immobilized CA in alginate beads would have the potential for CO2 sequestration by biomimetic route.