Metal-organic frameworks (MOFs) have been extensively studied as candidate materials for enzyme immobilization over recent years. In this work, carbonic anhydrase was immobilized in ZIFs by “in situ” immobilization method. The growth state of ZIF-8 was adjusted by adjusting the ratio of Zn 2+ and 2-Hmim to obtain crystals with different morphologies (cubic-, dodecahedral- and leaf-shape). In addition, different surfactants (cationic surface-active agent, an-ionic surfactant, and non-ionic surface-active agent) were added as “shape-inducing agents” to further regulate the crystal shapes, thus affecting the activity of enzyme immobilization in ZIFs. Through CO 2 absorption test, it was found that the thick leaf-shaped CA/ZIF-L-(PVP) induced by PVP had a higher relative activity (150%) than other shapes (cubic, dodecahedral, “burr puzzle” shape, “interpenetration leaves” shape, etc.) of immobilized enzymes. In addition, CA/ZIF-L-(PVP) exhibited excellent reusability and stability, which maintained a relative activity of 131% after 5 cycles, and remained approximately 99% relative activity after 15 days at 40 °C in MDEA solution.
Ran Ma,An-Hua Liu,Cheng-Bin Huang,Xue-Dong Li,Liang-Nian He
A green process was developed for efficient reduction of sulfoxides and pyridine-N-oxides using the iron powder in the presence of H2O–CO2 to sulfides and pyridines, respectively. Notably, H2O is employed as the terminal hydrogen source, and CO2 could enhance hydrogen generation through in situ formation of carbonic acid. Thus carbonic acid offers simple neutralization by depressurizing CO2 and the system can eliminate unwanted byproducts. The high generality and chemo-selectivity of this protocol were demonstrated by the scope of substrates, in which chlorine, vinyl group and benzene ring can be tolerated.
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