Recyclable laccase nano-catalyst based on aldehyde-β-cyclodextrin and Fe-ZIF for diclofenac degradation

Diclofenac (DCF), a commonly used non-steroidal anti-inflammatory pharmaceutical, causes harm to ecological environment safety. Thus, the degradation of DCF is of great value. Herein, we report a strategy to prepare a novel immobilised laccase (LAC), Fe-ZIF@β-CD-CHO-LAC, for DCF degradation. Benefiting from the unique and remarkable structure of aldehyde-β-cyclodextrin (β-CD-CHO), it can covalently bind Fe-ZIF and LAC. As a proof of concept, we prepare a novel, iron-based zeolitic imidazolate framework (Fe-ZIF) with a saturation magnetisation of 71.35 emu/g Fe and fabricate Fe-ZIF@β-CD-CHO-LAC via liquid-phase synthesis combined with chemical cross-linking. The catalytic activity of Fe-ZIF@β-CD-CHO-LAC is approximately 1.6 times that of free LAC, with a residual catalytic activity of 84 % after the 10th cycle and a cumulative catalytic activity 10.23 times that of free enzyme. Fe-ZIF@β-CD-CHO-LAC exhibits remarkable stabilities in terms of pH, temperature and storage. It also delivers an excellent performance in DCF degradation. Furthermore, Fe-ZIF@β-CD-CHO-LAC exhibits several attractive features, such as easy preparation, remarkable stability and excellent reusability, providing a novel and promising tool for DCF degradation.