Amino functionalized metal–organic framework as eco-friendly support for enhancing stability and reusability of horseradish peroxidase for phenol removal

Phenolic compounds are expected to be successfully removed from wastewater as pervasive environmental contaminants. For the removal of phenolic chemicals, enzymes such as horseradish peroxidase have shown to have a lot of promise. Horseradish peroxidase (HRP) was immobilized on amino functionalized metal organic frameworks (NH 2 -MOF-Zr) utilizing covalent bonds. The microstructural and physicochemical properties were investigated using Fourier transform infrared (FT-IR), X-Ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). The free HRP and NH 2 -MOF-Zr@HRP were characterized by determining the activity profile as a function of kinetic behavior, pH, storage stability, effect of organic solvent, and temperature. The Km and Vmax for NH 2 -MOF-Zr@HRP were estimated to be 34.7 mM, 0.811 U/mL for guaiacol and 12.58 mM, 0.930 U/mL for H 2 O 2 , respectively. The optimum pH values of the enzyme activity were found as 7 and 7–7.5 for the free HRP and NH 2 -MOF-Zr@HRP, respectively. The optimum temperature profile of the free HRP and NH 2 -MOF-Zr@HRP revealed as 40 °C and 50 °C, respectively. NH 2 -MOF-Zr@HRP maintained 74% of its initial activity after 6 weeks of storage and 59% of its initial activity after ten consecutive cycles of the guaiacol oxidation. A substantial degree of the phenolic compounds was removed by HRP immobilized on the NH 2 -MOF-Zr. About 87%, 53%, and 49% of 4-methoxyphenol (4-MEP), bisphenol A (BPA), and phenol were removed by NH 2 -MOF-Zr@HRP during a 6-h reaction. The removal efficiency of phenol, BPA, and 4-MEP after five reuse cycles was 48%, 51%, and 62%, respectively.