Facile construction of a robust and recyclable laccase/metal–organic framework-808 with boosted stability for biodegradation of Reactive Blue 171 and Reactive Blue 198 from aqueous media

Abstract

Laccase enzyme sees application demand in many industries such as textile, food processing, wood processing, pharmaceutical, and chemical. However, it becomes difficult to maintain the enzymatic activity of laccase under harsh reaction conditions and even after several biocatalytic cycles. Therefore, suitably prescribed supports are crucial to ensure that the catalytic activity and reusability of the immobilized laccase are maintained at high levels. The present study highlights the development and dye decolorization application of an enzyme carrier matrix employing a Zr-based metal-organic framework (MOF), MOF-808, with hierarchical porosity for the immobilization of laccase from Trametes trogii. The immobilization efficiency for Lac/MOF-808 was found to be 70.83 ± 1.98 %. Lac/MOF-808 exhibited optimal catalytic temperature at 60 °C, while the optimal catalytic pH was 4.5. Due to recoverable properties from the carrier matrix the recycle test was satisfactory for the Lac/MOF-808, being reused 7 times without losses greater than 50 % of residual activity. Stored at 25 °C, Lac/MOF-808 retained 30 % of its activity during 4-weeks period. A kinetic study was carried out for Lac/MOF-808 monitoring the oxidation reaction of ABTS. The Km value was 0.070 mM and the Vmax was 87.7 µmol min−1g−1. Kinetic investigations, on the other hand, demonstrated a decrease in Km following immobilization, signifying a higher affinity for substrate. The Lac/MOF-808 maintained its decolorization efficiency even after eight reaction cycles, exhibiting a remarkable activity of 56.7 % and 77.2 % against Reactive Blue 171 and Reactive Blue 198, respectively. Hence, the described Lac/MOF-808 might be an ideal candidate for efficient dye decolorization applications.