In situ encapsulation of laccase in mesoporous amorphous ZIF-8 for Reactive Blue 19 removal.

Abstract

Laccase with substrate non-specificity is particularly effective in pollutant degradation. However, the practical application of the laccase is limited due to its poor stability and reusability. In this study, a simple in situ encapsulation method was used to immobilize laccase into amorphous zeolitic imidazolate frameworks-8 (aZIF-8), and the synthesized Lac@aZIF-8 biocomposites were used to remove Reactive Blue 19 (RB 19). Results indicated that the presence of mesoporous endowed the immobilized laccase with higher substrate affinity. Compared with free laccase, the Lac@aZIF-8 showed higher thermo-tolerant performance, wider pH range, better storage stability, and reusability. The Lac@aZIF-8 biocomposites have excellent performance in the effective removal of RB 19. Without any mediators, the dye decolorization rate of immobilized laccase reached up to 82% in 3h under optimal conditions. Based on the LC-MS analysis, the proposed degradation pathways of RB 19 were discussed technically. Moreover, the growth inhibition experiments on Scenedesmus obliquus confirmed the lower toxicity intensity of the degradation products. This research enhanced the stability of laccase while maintaining high substrate affinity, providing a novel strategy for the green and efficient treatment of dye wastewater. PRACTITIONERS POINTS: Lac@aZIF-8 was synthesized by a simple in situ encapsulation method. The mesoporous structure endows the immobilized laccase with higher substrate affinity. The Lac@aZIF-8 shows higher thermo-tolerant performance, wider pH range, better storage stability, and reusability. The Lac@aZIF-8 biocomposites have excellent performance in RB 19 removal.