Immobilization of Glucose Oxidase on Fe3O4 Magnetic Nanoparticles and its Application in the Removal of Acid Yellow 12

In this study, the decolorization of a dye solution via bio-Fenton process with in situ generation of H₂O₂ by enzymatic catalyzed oxidation of glucose was investigated. For this purpose, magnetite was synthesized and was used as the support for glucose oxidase immobilization. The particle size of the magnetite was estimated to be around 42 nm according to the obtained scanning electron microscope images. The magnetite crystal size was obtained approximately 26 nm by X-ray diffraction spectrum. Effective variables on immobilization were investigated. The best immobilization conditions were achieved at pH 6, temperature of 10 °C, glucose oxidase/support ratio of 1800 U/g, and time of 2.5 h. In these conditions, 450 U of glucose oxidase was immobilized per grams of magnetite. The immobilized glucose oxidase was used for the decolorization of acid yellow 12 in batch experiments. Decolorization conditions were optimized by response surface methodology. Four parameters including pH, temperature, glucose, and Fe²⁺ concentrations in five levels were investigated. The optimum conditions were obtained as follows: pH = 4.5, T = 29 °C, initial glucose concentration of 1.5 g/L, and Fe⁺² concentration of 1.4 g/L. Decolorization efficiency after 120 min at optimal conditions in the presence of 0.3 g immobilized enzyme (450 U/g) in 100 cm³ solution was observed to be equal to 62.27 %.