Application of an industrial waste magnetic iron dust as a solid phase support for immobilizing enzyme of industrial applications

Magnetic iron dust, a byproduct by many chemical industries that performs the reduction of nitro compounds to amine, was used for laccase immobilization. The characterization of magnetic iron dust was done by X-ray diffraction, Fourier-transform infrared, and dynamic light scattering. Biodegradable polymer, chitosan, was coated on to the magnetic iron dust by reverse phase suspension method, which was confirmed by Fourier-transform infrared analysis. Immobilization of the laccase enzyme was done onto the chitosan-coated and non-coated magnetic iron dust. The immobilization was monitored by Fourier-transform infrared analysis. Binding efficiency, optimum pH, and optimum temperature for these immobilized laccases were investigated. X-ray diffraction pattern of magnetic iron dust confirmed presence of magnetite (Fe3O4) and maghemite (γ-Fe2O3) with a particle size of 529.6 nm measured by dynamic light scattering. Laccase was immobilized on chitosan-coated and non-coated magnetic iron dust, monitored by Fourier-transform infrared spectra. Binding efficiency of the laccases was found to be 100% onto the coated and non-coated magnetic iron dust and their activity remained to be 63% and 82%, respectively, even after the 10th cycle of their use. The present results demonstrated the applicability of these immobilized laccase system in the industry in terms of their reusability and waste recycling.