Immobilization of carbonic anhydrase on chitosan beads for enhanced carbonation reaction

Carbonic anhydrase (CA) has been immobilized on chitosan beads and has been tested for its activity using p-NPA. CA immobilized chitosan beads were further tested for targeted application of carbonation reaction to convert CO2 to CaCO3. It was observed that onset time for precipitation of CaCO3 was 40 s for immobilized catalyst as compared to non-catalyzed system (100 s). Mechanistic and kinetic aspects have been addressed for immobilized catalyst as well as free CA using p-NPA assay. Km and Vmax of the immobilized CA was observed to be 2.36 mM and 0.54 μmoles/min/ml as compared to Km and Vmax of 0.87 mM and 0.93 μmoles/min, respectively, for free CA. Storage stability test was conducted up to 20 days and it was observed that at −20 °C, the Half Life Period (HLP) of immobilized CA was 216 h as compared to 192 h for free CA whereas at 25 °C the HLP for immobilized and free CA was observed to be 456 h and 408 h, respectively.