Laccase Integrated Fe-Squaric Acid Complex as Biomimetic Nanozyme for the Construction of PVDF-Based Mixed-Matrix Membrane with Enhanced Dye Removal Efficiency.

Nanozyme/enzyme hybrid heterogeneous catalysts have attracted significant attention in the fields of biocatalysis and environmental remediation due to their integrated advantages of reusability, high stability, and catalytic selectivity. In this study, a hybrid biocatalyst (Lac@Fe-SS) composed of Fe-squaric acid complex (Fe-SS) and laccase (Lac) was first synthesized under mild conditions. Lac@Fe-SS was subsequently incorporated into a matrix (poly(ethylene glycol) (PEG) and poly(vinylidene fluoride) (PVDF)) through a casting method. The resulting composite film (Lac@Fe-SS@PEG/PVDF) was evaluated for its potential for degrading indigo carmine (IC) in aqueous solutions. The physical and chemical properties of the Lac@Fe-SS@PVDF/PEG membrane were extensively characterized using a range of analytical techniques (e.g., XRD, FT-IR, SEM, AFM). The membrane exhibited excellent removal efficiency for IC degradation, achieving over 99% removal within 20 min. This enhanced catalytic performance could be attributed to the synergistic catalysis between the Fe-SS complex and laccase. Furthermore, the hybrid biocatalyst demonstrated outstanding stability and reusability, likely due to the protective effect of Fe-SS on the laccase. The developed nanozyme/enzyme composite film represents a promising approach for enzyme immobilization and highlights its great potential for industrial applications in textile wastewater treatment.