Immobilized carbonic anhydrase on mesoporous cruciate flower-like metal organic framework for promoting CO 2 sequestration

CO capture by immobilized carbonic anhydrase (CA) has become an alternative and environmental friendly approach in CO sequestration technology. However, the immobilized CA usually exhibits low CO sequestration efficiency due to no gas adsorption function for the conventional CA supports. Metal organic frameworks (MOFs) are an excellent material for gas adsorption and enzyme immobilization. Herein, a combined immobilization system of CA and ZIF-8 with cruciate flower-like morphology for CO adsorption was prepared for the first time by adsorbing CA onto ZIF-8. The immobilization efficiency was greater than 95%, and the maximum activity recovery reached 75%, indicating the highly efficient immobilization process. The resultant CA@ZIF-8 composites exhibited outstanding thermostability, the tolerance against denaturants, and reusability compared with free CA. Furthermore, we demonstrated for the first time that the shape of ZIF-8 could be controlled by adjusting concentrations of Zn ions at the high concentration of 2-methylimidazole (1 M). More importantly, we also demonstrated the applicability of the CA@ZIF-8 composites to the sequestration of CO in carbonate minerals. The yields of the CaCO obtained by using CA@ZIF-8 composites were 22-folds compared to free CA. Thus, this CA@ZIF-8 composite can be successfully used as a robust biocatalyst for sequestration of CO .