Production of biodiesel from renewable sources such as inedible vegetable oils by enzymatic catalysis has been a hotspot but remains a challenge on the efficient use of an enzyme. COFs (Covalent Organic Frameworks) with large surface area and porosity can be applied as ideal support to avoid aggregation of lipase and methanol. However, the naturally low density limits its application. In this work, we reported a facile synthesis of core–shell magnetic COF composite (Fe3O4@COF-OMe) to immobilize RML (Rhizomucor miehei lipase), to achieve its utilization in biodiesel production. This strategy gives extrinsic magnetic property, and the magnetic COFs is much heavier and could disperse in water medium well, facilitating the attachment with the enzyme. The resultant biocomposite exhibited an excellent capacity of RML due to its high surface area and fast response to the external magnetic field, as well as good chemical stability. The core–shell magnetic COF-OMe structure not only achieved highly efficient immobilization and recovery processes but also maintained the activity of lipase to a great extent. RML@Fe3O4@COF-OMe performed well in practical applications, while free lipase did not. The biocomposite successfully achieved the production of biodiesel from Jatropha curcas Oil with a yield of about 70% in the optimized conditions. Magnetic COFs (Fe3O4@COF-OMe) for RML immobilization greatly improved catalytic performance in template reaction and biodiesel preparation. The magneticity makes it easily recovered and separated from the system. This first successful attempt of COFs-based immobilized enzyme broadened the prospect of biodiesel production by COFs with some inspiration.

中文翻译：

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磁性COFs作为脂肪酶固定和回收的满意支持，通过保持酶活性有效实现生物柴油的生产

通过酶催化从不可食用植物油等可再生资源生产生物柴油一直是一个热点，但仍然是有效利用酶的挑战。具有大表面积和孔隙率的 COF（共价有机框架）可用作理想的支持物，以避免脂肪酶和甲醇的聚集。然而，天然的低密度限制了它的应用。在这项工作中，我们报道了一种简单的核壳磁性 COF 复合材料（Fe3O4@COF-OMe）的合成方法来固定 RML（Rhizomucor miehei 脂肪酶），以实现其在生物柴油生产中的应用。这种策略赋予了外在磁性，磁性 COFs 更重，可以很好地分散在水介质中，促进与酶的附着。由于其高表面积和对外部磁场的快速响应以及良好的化学稳定性，所得生物复合材料表现出优异的 RML 容量。核壳磁性COF-OMe结构不仅实现了高效的固定和回收过程，而且在很大程度上保持了脂肪酶的活性。RML@Fe3O4@COF-OMe 在实际应用中表现良好，而游离脂肪酶则不然。该生物复合材料在优化条件下成功实现了麻疯树油生产生物柴油，产率约70%。用于 RML 固定的磁性 COFs (Fe3O4@COF-OMe) 大大提高了模板反应和生物柴油制备的催化性能。磁性使其易于回收并与系统分离。