Immobilization of carbonic anhydrase on carboxyl-functionalized ferroferric oxide for CO2 capture.

New materials of Fe3O4 magnetic microspheres were functionalized with carboxyl and prepared for carbonic anhydrase (CA) immobilization to capture CO2. The optimum conditions for immobilization, such as carrier dose, enzyme dose, pH, shaking speed, temperature and contact time, were determined. The pH and thermal stability of the free and the immobilized CA were compared. The results presented that the immobilized CA had a better enzyme activity, a higher pH and thermal stability than that of the free CA. Meanwhile, CO2 capture was respectively enhanced by the free and the immobilized CA in tris(hydroxymethyl) aminomethane (Tris) buffer solution. Moreover, the immobilized CA maintained 58.5% of its initial catalytic ability even after ten recovery cycles due to the protest of the magnetic microspheres. All the results confirmed the potential use of the carboxyl-functionalized Fe3O4 magnetic microspheres immobilized CA to remove CO2 from air or flue gas.