Pickering interfacial biocatalysis with enhanced diffusion processes for CO2 mineralization

Abstract

Utilization of carbon dioxide (CO2) has become a crucial and anticipated solution to address environmental and ecological issues. Enzymes such as carbonic anhydrase (CA) can efficiently convert CO2 into various platform chemicals under ambient conditions, which offers a promising way for CO2 utilization. Herein, we constructed a Pickering interfacial biocatalytic system (PIBS) stabilized by CA-embedded MOFs (ZIF-8 and ZIF-L) for CO2 mineralization. Through structure engineering of MOFs and incorporation of Pickering emulsion, the internal and external diffusion processes of CO2 during the enzymatic mineralization were greatly intensified. When CO2 was ventilated at a flow rate of 50 mL min–1 for 1 h, the pH value of PIBS dropped from ~8.00 to ~6.50, while the average pH value of free system only dropped to ~7.15, indicating that the initial reaction rate of CO2 mineralization of PIBS is nearly twice that of the free system. After the 8th cycle reaction, PIBS can still produce more than 9.8 mg of CaCO3 in 5 min, realizing efficient and continuous mineralization of CO2.