Fe3O4/Acid activated montmorillonite/cellulase composites: Preparation, structure, and enzyme activity

Abstract In the present work, a series of Fe3O4/acid activated montmorillonite (Mt K-10) composites were prepared by chemical co-precipitation method and used as supports for immobilization of cellulase. The structure of composites and their effects on the adsorption and activity of cellulase were studied. In Fe3O4/Mt K-10 composite, the Mt K-10 layers were exfoliated and the size of formed Fe3O4 particles could be controlled by varying the amount of Mt K-10. The results showed that the amount of adsorbed cellulase and activity recovery of immobilized cellulase were affected by the mass ratio (Fe3O4/Mt K-10). As the mass ratio (Fe3O4/Mt K-10) increased from 1:3 to 1:1 the amount of adsorbed cellulase increased from 704.6 mg/g to 860.8 mg/g and the activity recovery of immobilized cellulase increased from 45.66% to 51.88%. The enzyme activity was linked to its structure. Therefore, the effect of Fe3O4, Mt K-10 and Fe3O4/Mt K-10 composite on the structure of cellulase had been investigated by Fourier transform infrared spectroscopy. It was found that the cellulase immobilized on Mt K-10 contained a higher fraction of α-helix and lower fraction of β-sheet than those of cellulase immobilized on Fe3O4/Mt K-10 composite. Cellulase immobilized on the low-cost and recyclable Fe3O4/Mt K-10 composite which can be employed in the enzymatic degradation of lignocellulose biomass.