Design and preparation of stable CPO/HRP@H-MOF(Zr) composites for efficient bio-catalytic degradation of organic toxicants in wastewater

BACKGROUND Immobilization of enzyme on a solid support can improve its stability, however, this is often accompanied by a decrease of the initial catalytic activity. The design and preparation of immobilized enzyme with simultaneous high activity and stability is a challenge. RESULTS A hierarchically porous metal organic framework H-MOF(Zr) which was prepared by 'crystal defect' strategy was very stable in aqueous solution and possessed well-defined, tunable and adjacent hierarchical pores. When using the H-MOF(Zr) as support for enzyme immobilization, a single array of enzyme in a single mesoporous channel was achieved so as to avoid aggregation of the enzyme. Meanwhile the micropores can be utilized to concentrate substrates, resulting in a decrease in the mass transfer resistance of substrate compared with that in the bulk buffer due to the enzymes and substrates closely embedded on the same support. The prepared immobilized enzyme CPO/HRP@H-MOF(Zr) was more stable at elevated temparatures, showing 58.2% enhanced activity compared with free enzymes at 70 degrees C for 1 h incubation. After 12 cycles, 70.7% of activity remained. When the CPO/HRP@H-MOF(Zr) was applied in the treatment of wastewater containing isoproturon and 2,4-dichlorophenol, complete degradation was achieved in only 15 min. CONCLUSION Both high activity and stability under harsh reaction conditions give the CPO/HRP@H-MOF(Zr) composites potential for practical application in wastewater treatment. (c) 2018 Society of Chemical Industry