Laccase immobilization on bimetallic MOF‐derived porous carbon materials for the removal of bisphenol A

Abstract

As a result of the poor mechanical properties of most metal-organic frameworks (MOFs), they are liable to dissociate in water and thus cannot maintain immobilized enzyme activity. In this paper, a magnetic porous carbon material (Fe-Cu-MPC) with good stability was prepared by high temperature carbonization using a bimetallic Fe-Cu-MOF precursor, and used to immobilize laccase by a simple and rapid adsorption-crosslinking method. Optimized by the response surface method, optimal conditions for the immobilization of laccase on Fe-Cu-MPC were obtained as follows: enzyme concentration 1.275 mg mL −1 , immobilization time 32 min, and pH 4.7. Under the optimal preparation conditions, the activity of the immobilized laccase obtained was 0.63 U mg −1 , with activity recovery of 63.13%. The enzyme loading was 189.03 mg g −1 and the immobilization yield was 74.13%. Compared with free laccase, Fe-Cu-MPC@Lac showed stronger tolerance to temperature and pH, and had better thermal stability and storage stability. The removal of BPA by immobilized laccase was studied, showing that the removal effect of Fe-Cu-MPC@Lac on BPA was much higher than that of free laccase. Within 5 h, the BPA removal amount of Fe-Cu-MPC@Lac (0.34 mmol g −1 ) was two-fold that of free laccase (0.14 mmol g −1 ), and the BPA removal rate reached 41.35% after ten cycles. Finally, based on the intermediates identified by gas chromatography-mass spectrometry, two possible degradation pathways of BPA were proposed. Studies have shown that Fe-Cu-MPC is an excellent carrier and Fe-Cu-MPC@Lac has great potential in the treatment of BPA containing wastewater.

Preparation of Ordered Macroporous ZIF-8-Derived Magnetic Carbon Materials and Its Application for Lipase Immobilization

“…However, the acid stability of ZIF-8 is poor and its crystal structure can be damaged by fatty acids and other substances, which limits the application of ZIF-8 immobilized lipases [12]. The chemical stability of the materials can be effectively enhanced by obtaining their derived porous carbon materials through high-temperature pyrolytic carbonization, which is due to the fact that the structure of carbon materials mainly relies on covalent bonds [13,14]. Our group has already prepared single-crystal macroporous ZIF-8-derived carbon materials using a hard template method-pyrolytic carbonization strategy and successfully applied them to immobilized lipases [12].…”