Biomineralization of orange peel peroxidase within metal organic frameworks (OPP-MOFs) for dye degradation

In an attempt to make the biocatalyst preparation economically viable, the peroxidase enzyme extracted from orange peel (Citrus sinenses, a fruit waste) was immobilized within metal-organic framework (MOF) via self-assembled biomineralization method. The synthesis of OPP-MOF was accomplished by simply mixing 2-methylimidazole (24 mmol), zinc acetate (8 mmol) and orange peel extract at room temperature within 30 min. The obtained OPP-MOF was confirmed by using different characterization methods such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM). The half-life of OPP-MOF was determined in the temperature range of 40-60 degrees C which showed 2.1 folds enhanced thermal stability as compared to free enzyme. Further, Michaels constant (K-M) and maximum rate (V-max) values of OPP-MOF were evaluated by Michaelis-Menten kinetics studies which showed higher K-M and lower V-max as compared to native peroxidase. Furthermore, peroxidase-MOF retained 48% residual activity after 6th cycle. Also, the storage stability studies of OPP-MOF revealed that there was no significant loss in its activity till 18 days. Finally, immobilized OPP-MOF was used for degradation of methylene blue (MB) and congo red (CR) dye, and it was found to be more efficient and rapid.