Modified PAN Nanofibers Immobilized With Laccase And Their Catalytic Properties

In this paper, in order to obtain amidoxime-modified PAN nanofibers （AOPAN）, PANnanofibers spun by electrospinning technique were modified in hydroxylamine hydrochloridesolution. Then the catalytic properties for dye of the AOPAN nanofibers coordinated withdifferent metal ions were discussed. Finally, the PAN nanofibers coordinated with differentmetal ions （M-AOPAN） were used as carrier for laccase, and the effects of different metalions on immobilized performance, as well as the catalytic properties of immobilized laccasefor dye were investigated in this work.The existence of amidoxime group on the surface of AOPAN nanofibers confirmed IRspectrum successfully, at the same time, the SEM image demonstrated the modification didn’tlead to some change and damages on surface morphology of AOAPAN nanofibers. Then itwas demonstrated via IR spectrum that the amidoxime groups on AOPAN nanofibers werecoordinated with different metal ions. The metal ions were occurred on the AOPANnonafibers By EDAX spectrum analysis. It can be seen from the SEM images that theM-AOPAN still maintained a good state of fiber, meanwhile, strength testing could prove thatthe strength of modified PAN nanofibers did not damage seriously, which were beneficial toreuse of nanofiber membranes.The PAN nonafibers coordinated with Four kinds of metal ions (Fe3+、Cu²⁺、Co²⁺、Cd²⁺)could constitute Fenton-catalytic system with hydrogen peroxide oxidation to degradeReactive Orange K-G dye. The results showed that the catalytic activities of M-AOPANnanofibers were ordered Fe-AOPAN>Cd-AOPAN>Co-AOPAN>Cu-AOPAN, which wereresulted from that the ions on the nanofibers were easy to gain electrons or not. The researchshowed increasing the quality of M-AOPAN nanofibers or the amount of metal ionscoordinated on the fibers could improve the catalytic effect of Reactive Orange K-G dyedegradation significantly. Experiments indicated that M-AOPAN nanofiber still could showcatalytic activity of degradation Reactive Orange K-G Dye after twice reuse. At the last of thispart, we found Fe-AOPAN nanofibers of were easier to achieve balance in the reaction systemvia a kinetic study.Immobilized laccase could be obtained by the coordination bonds between the metal ionson M-AOPAN nanofibers and laccase macromolecules. The immobilized laccase expressedbetter resistance of temperature and pH than that of free laccase, as well as the storagestability.. Meanwhile, reusability as the outstanding advantages of the immobilized enzymehad also been confirmed. It could be proved by catalytic research that immobilized laccasehad catalytic effect on degradation Reactive Red Dye, and Fe3+had inhibition to catalyticactivity of laccase, however, Cu²⁺, Co²⁺and Cd²⁺had no effect on that. Also, the result of Michaelis-Menten equation demonstrated that the maximum reaction rate and the affinity withthe substrate of the immobilized laccase had decreased respectively. Finally, from theexperimental results we could see that the catalytic activity of immobilized laccase did notreduce seriously after three times reuse.