Biocatalytic decolorization of azo dye-containing wastewater by immobilizing metagenome-derived laccase on green synthesized Co-doped NiO NPs

Abstract

Efficient removal of toxic dyes from wastewater is crucial for environmental protection. Laccases are enzymes that have been proposed as potential solutions to reduce the devastating effects of toxic dyes with recalcitrant structures present in complex wastewater. However, instability of laccases has been identified as a major issue. This study aimed to develop a carrier matrix based on Co-doped NiO NPs to improve the stability of the metagenome-derived laccase PersiLac1 and achieve high removal efficiency of Azo dye-containing wastewater. The immobilization of laccase led to improved enzymatic activity over a broader range of pH and temperature. After 15 reuse cycles, the immobilized enzyme retained 57.99 % of its initial activity. The immobilized enzyme demonstrated great potential for the biodecolorization of Congo red over broad pH and temperature ranges, with 66.23 % decolorization achieved after 60 min under optimal conditions. Treatment with real textile wastewater containing an extremely high concentration of Azo dye resulted in more than 92 % dye removal. After 20 cycles of operation, the immobilized enzyme retained 87.66 % of its initial decolorization capability. This study presents Co-doped NiO NPs-PersiLac1 as an efficient, stable, and cost-effective biocatalytic system for Azo dye-containing removal processes in textile effluents.