Covalent Immobilization of Laccase on Mesoporous Bismuth Silicate for High‐Performance Biodegradation of Contaminants

Bismuth silicate (BiSi‐ext) was synthesized hydrothermally using tetrapropylammonium bromide (TPA·Br) as an organic structure‐directing agent at 200°C under autogenous pressure for 7 days. Soxhlet extraction of the template yielded phase‐pure bismuth silicate, indexed to an orthorhombic unit cell ( a = 23.234 Å, b = 17.109 Å, c = 3.897 Å), consistent with a highly anisotropic, layered framework. The material exhibited a high specific surface area (310 m 2 ·g −1 ) and mesopore volume (0.36 cm 3 ·g −1 ). Covalent immobilization of Myceliophthora thermophila laccase onto the silanized, glutaraldehyde‐activated support produced Lac–GA–APTES–BiSi‐ext. Bioinformatic modeling revealed that immobilization at Lys188 expanded the active‐site pocket volume from 342 to 423 Å 3 , enhancing substrate accessibility. The biocatalyst demonstrated improved thermal stability, reusability, and catalytic efficiency, achieving complete decolorization of Tectilon Blue 4R‐01 200% and ∼73% degradation of ibuprofen within 2 h at 40°C. Mechanistically, laccase performs single‐electron oxidation at the dye's secondary amine to generate N‐centered radicals and •OH; these species—directly or via in situ H 2 O 2 /Cu‐assisted Fenton‐like chemistry—drive aromatic hydroxylation, ring opening to muconic‐type/polycarboxylated intermediates, and stepwise decarboxylation. These results establish Lac–GA–APTES–BiSi‐ext as a robust, scalable, and eco‐friendly platform for advanced wastewater remediation targeting pharmaceutical residues and recalcitrant dyes.