Co-precipitation synthesis of carbonic anhydrase-embedded magnetic zeolitic imidazolate framework-8 nanocomposite enzyme for enzymatic CO2 conversion and utilization in facilitating uranium extraction

Carbonic anhydrase (CA)-mediated carbon conversion and utilization (CCU) technology is recognized as an eco-friendly and cost-effective strategy for carbon reduction. However, the broader application of this technology is significantly constrained by the operational instability and challenging recyclability of free CA . Fortunately, nano-integrated biocatalysis has emerged as an effective solution to these challenges. In this study, we immobilized CA for the first time as a CA-embedded ferriferous oxide-zeolite imidazolium framework-8 (Fe 3 O 4 @ZIF-8@CA) nanocomposite enzyme through a one-pot co-precipitation strategy, integrating both the in-situ growth of ZIF-8 around the Fe 3 O 4 core and the immobilization of CA within a single step. Subsequently, this nanocomposite was employed as a nano-integrated biocatalyst to facilitate an innovative CCU pathway. This pathway leverages bicarbonate, produced from the enzymatic hydration of carbon dioxide (CO 2 ), as a substantive uranyl complexing agent to facilitate the neutral leaching of sandstone uranium ore. Systematic characterization techniques, including SEM, TEM, XRD, FTIR, TGA, CLSM, and MPMS, confirmed that Fe 3 O 4 @ZIF-8@CA, which possesses a core–shell structure and excellent magnetic responsiveness, has been successfully synthesized. Enzymatic assays revealed that Fe 3 O 4 @ZIF-8@CA retains approximately 79% of the activity compared to its free counterparts while demonstrating significantly enhanced thermal and storage stability. The outcome of CO 2 hydration conversion for facilitating uranium extraction indicated that, compared with the non-enzymatic reaction group, the bicarbonate yield increased up to 1.5 times, and the uranium extraction efficiency was nearly 10% higher in the Fe 3 O 4 @ZIF-8@CA-mediated reaction group. These findings suggest that Fe 3 O 4 @ZIF-8@CA possesses excellent catalytic properties for CO 2 hydration and can achieve multiplied decarbonization by mediating this innovative CCU pathway. Furthermore, Fe 3 O 4 @ZIF-8@CA demonstrated superb reusability and durability, experiencing no significant degradation in its catalytic performance after eight consecutive hydration regeneration cycles. Our research is anticipated to be a viable option for advancing the goals of carbon neutrality and sustainable development.