Accelerated CO2 capture using immobilized carbonic anhydrase on polyethyleneimine/dopamine co-deposited MOFs

Immobilized carbonic anhydrase (CA, EC4.2.1.1) for CO 2 capture has been intensively investigated. Unfortunately, the immobilized CA usually shows low CO 2 capture efficiency due to lack of CO 2 capture function for the conventional CA supports. In this study, an acid-resistant metal-organic framework MOF-808 was first modified by co-deposition of PEI (polyethyleneimine) and PDA (polydopamine) (PEI/PDA-MOF-808). Subsequently, the PEI/PDA-MOF-808 with a large number of amino groups was used as the strengthening material of CO 2 capture to immobilize CA (CA@PEI/PDA-MOF-808). The resultant CA@PEI/PDA-MOF-808 showed a considerably improved CO 2 capture capacity compared with free CA and PEI/PDA-MOF-808. The amount of CaCO 3 produced by CA@PEI/PDA-MOF-808 was 11.0-fold and 2.5-fold higher than free CA and PEI/PDA-MOF-808, respectively. After 8 consecutive rounds of CO 2 conversion, the total production of CaCO 3 by CA@PEI/PDA-MOF-808 was 92-fold higher than free CA, reaching 294.0 mg. Furthermore, CA@PEI/PDA-MOF-808 displayed high thermostability , pH stability, storage stability, and reusability compared with free counterpart. After 1 h treatment at pH 3.0, CA@PEI/PDA-MOF-808 preserved 53.6% of its original activity while free CA was almost inactivated. In conclusion, this work provides a promising strategy for enzymatic CO 2 conversion.