The Preparation Of Novel Horseradish Peroxidase Complex Nanoparticle Catalysts And Degradation Of Phenol Contaminants

Enzyme is a natural catalyst with high activity and high selectivity,and it has good biocompatibility and recycling ability.In recent years,with the development of the enzyme industry,enzymes have been widely used in food industry,biomedicine,textile engineering,sewage treatment and other industries.However,the methods for immobilizing enzymes still have many problems such as low enzyme activity,poor cycling ability,and unsatisfactory results in practical applications.And an important way to solve this problem is to improve the carrier material and change the immobilization method.In this paper,we chose horseradish peroxidase?HRP?as our research basis.We searched many solutions such as magnetic nanospheres loading target enzymes,synthesizing magnetic nanoflowers and loading target enzyme by g-C₃N₄ to solve the problems existing in current researches on immobilized enzymes.The specific experiment content is listed as follows:?1?In this part,a new type of functionalized magnetic nanospheres Fe₃O₄@p?AABOB-co-AIM?-Ni²⁺was synthesized and characterized.As we know,Phenylboronic acid can form a stable six-membered ring structure with the O-dihydroxy group on horseradish peroxidase.And nickel ion on the surface of the magnetic ball can react with the amino group on horseradish peroxidase.These two effects work together for the immobilization of horseradish peroxidase in this study.In this experiment,we investigated the influence of the amount of the cross-linking agent,the pH and the ratio between the two ligands on the immobilization of the enzyme.The enzyme immobilization under optimal conditions was 174.75 mg g-1,which was much higher than that reported in the current literature.The loading capacity of HRP under optimal conditions was 174.75 mg g^-1,much higher than that reported in the current literature.In addition,the new synthetic immobilized enzyme has strong reusability.It can also be separated in 30s in the presence of an external magnetic field,and the enzyme activity can still reach 83%after 5 cycles.The enzymatic properties of this immobilized enzyme also have some improvements,including temperature stability,pH stability and storage stability.we also used this immobilized enzyme for the degradation of phenol,which has a significant increase in the degradation rate of phenol compared to free enzyme.?2?In this part,a new type of magnetic nanospheres Fe₃O₄@PMG@IDA-Cu²⁺was synthesized and characterized to form a new type of magnetic nanoflowers.We investigated the effects of many factors in the synthesis of nanoflowers,such as enzyme concentration,pH,synthesis time,concentration of phosphate buffer solution,etc.And the optimal synthesis conditions were listed as follows:horseradish peroxidase concentration was 0.5 mg mL^-1;pH was 7;the synthesis time was 8 hours;concentration of phosphate buffer solution was 0.2 mol L^-1.It can also be separated rapidly in the presence of an external magnetic field,and the enzyme activity can still reach 78%after 6 cycles.In addition,the temperature stability,pH stability,and storage stability of this magnetic nanoflower also have a clearly increase.Finally,we also discussed the ability of synthesized magnetic nanoflowers for the degradation of bisphenol A.The degradation process,such as the concentration of bisphenol A,the concentration ratio of hydrogen peroxide and bisphenol A,the concentration of magnetic nanoflowers added,and the temperature of the reaction system,were optimized.The ability of synthesized magnetic nanoflowers to degrade Bisphenol A is significantly higher than that of free enzymes,which can degrade more than 90%of bisphenol A within 30 minutes.?3?AnewtypeofHRP-C₃N₄compositephotocatalyticmaterial,g-C₃N₄/Ni-HRP,was designed and synthesized to further study the enhancement of horseradish peroxidase degradation of phenolic contaminants.We adjusted the ratio of g-C3N4,Ni and horseradish peroxidase to achieve the best photocatalytic degradation performance.And the optimal synthesis conditions were listed as follows:50 mg g-C3N4;3 mg Ni;1 mg horseradish peroxidase.Without the addition of hydrogen peroxide,the synthesized composite material can completely degrade bisphenol A within 40 minutes,which degradation ability has significantly improved compared with previous studies.In addition,the reusability of the material was also discussed.After 4 cycles,its degradation capacity did not decrease significantly,indicating good stability of the synthesized material.