Study on porous HZIF-8 immobilized enzyme and its performance in phenol degradation
Using hydrogel as template,zinc based MOF material HZIF-8 was prepared by template emul-sification method,and horseradish peroxidase was immobilized by the combination of embedding method and cross-linking method.The effects of temperature,pH and phenol concentration on the degradation of phenol by HZIF-8 immobilized enzyme were studied.The results showed that the optimum temperature of immobilized enzyme was raised to 50℃,and the optimum pH was 7.The environmental tolerance of HZIF-8 immobilized enzyme was much higher than that of free enzyme.The half-life is 16 d.When the immobilized enzyme was placed for 10 d,the relative enzyme activity still reached 82%,124.64 U/mg.The best degradation condition of HZIF-8 immobilized enzyme:50℃,pH = 8.The relative enzyme activity was still above 50%after 6 times of recycling.The Km values of acid radical peroxidase(HRP)and HZIF-8 immobilized enzyme were 9.57 mmol/L and 5.69 mmol/L,respectively.The affinity of HZIF-8 immobilized enzyme to substrate is higher than that of free enzyme,its catalytic efficiency is higher than that of free HRP,and the operational stability and activity of immobilized enzyme are also significantly enhanced.
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