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Amidoxime polyacrylonitrile (AOPAN) nanofibrous membranes were generated by the reaction between electrospun polyacrylonitrile nanofibrous membranes and hydroxylamine hydrochloride. AOPAN nanofibrous membranes were further modified by Fe(III) chelation for immobilizing catalases with coordination bonds. The surface morphologies of the nanofibrous membranes and immobilized catalases were observed by field emission scanning electron microscopy. Chelation of Fe(III) onto AOPAN nanofibrous membranes was studied by the Langmuir isothermal adsorption model. It was found that the maximum amount of coordinated Fe(III) (qm) was 4.5045 mmol g−1 (dry nanofibrous membranes) and the binding constant (Kl) was 0.0698 L mmol−1. The amounts of immobilized enzymes were determined by the method of Bradford. Kinetic parameters were analyzed for both immobilized and free catalases. The value of Vmax (7122.6 µmol mg−1 min−1) for the immobilized catalases was smaller than that for the free catalases (9203.2 µmol mg−1 min−1), and the Km for the immobilized catalases was larger. The immobilized catalases showed better resistance to pH and temperature change than the free catalases, and the storage stability of immobilized catalases was higher than that of free catalases. As for reusability, the immobilized catalases retained 71% of their activity after eight repeated uses. © 2012 Society of Chemical Industry

PVA/PA6 composite nanofibers were formed by electrospinning. Cu(II)-PVA/PA6 metal chelated nanofibers, prepared by the reaction between PVA/PA6 composite nanofibers and Cu2+ solution, were used as the support for catalase immobilization. The result of the experiments showed that PVA/PA6 composite nanofibers had an excellent chelation capacity for Cu2+ ions, and the structures of nanofibers were stable during the reaction with Cu2+ solution. The adsorption of Cu(II) onto PVA/PA6 composite nanofibers was studied by the Langmuir isothermal adsorption model. The maximum amount of coordinated Cu(II) (qm) was 3.731 mmol/g (dry fiber), and the binding constant (Kl) was 0.0593 L/mmol. Kinetic parameters were analyzed for both immobilized and free catalases. The value of Vmax (3774 &mu, mol/mg&middot, min) for the immobilized catalases was smaller than that of the free catalases (4878 &mu, min), while the Km for the immobilized catalases was larger. The immobilized catalases showed better resistance to pH and temperature than that of free form, and the storage stabilities, reusability of immobilized catalases were significantly improved. The half-lives of free and immobilized catalases were 8 days and 24 days, respectively.

Ployacrylonitrile (PAN) nanofibers were formed by electrospinning. Amidoxime polyacryonitrile (AOPAN) nanofibrous membranes were formed by reaction between PAN nanofibrous membranes and hydroxylamine hydrochloride, and Fe(III)-AOPAN metal chelated nanofibrous membranes were prepared for immobilizing catalases. The enzymatic membrane reactor (EMR) with immobilized catalases was assembled, and the fluxes of membrane and conversion ratio of EMR were studied. The immobilized catalases showed better resistance to pH and temperature change than that of the free form, and the storage stabilities of immobilized catalases were higher than that of the free catalases. The flux of the membrane and the conversion ratio of EMR were calculated, and the reusability of the EMR was studied. The results of experiments show that the immobilized catalases had a high affinity with the nanofibers, and the EMR has excellent performance.