Multifunctional quaternary ammonium-modified TEMPO-oxidized cellulose nanofibers and MIL-100 with encapsulated laccase for efficient removal of anionic arund cationic dyes in wastewater.

Abstract

The increasing prevalence of micropollutants like cationic and anionic dyes in wastewater creates an influential environmental challenge, mainly due to their toxic effects and persistence. Current methods often lack the efficiency and versatility to cope with a wide variety of contaminants. This study explores the modification of TEMPO-oxidized cellulose nanofibers (TOCNF) using (3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHPTAC) to enhance their cationic properties. Laccase was immobilized within the MIL-100 framework and integrated into the cationized TOCNF network. The optimum enzyme concentration was obtained using Lowry's method equal to 2.5 mg/L, and the efficiency of enzyme immobilization at this concentration was 61%. Immobilized laccase in nanocomposite showed maximum activity at 30 °C and pH = 4. The performance of the nanocomposite with cationized-TOCNF was superior to the unmodified cellulose nanofiber nanocomposite (TOCNF), which effectively absorbs and degrades the cationic dye crystal violet and the anionic dye acid orange 7 with an efficiency of 95 and 98%, respectively. The multifunctional cellulose nanofibers increases the adsorbent potential against a wide range of micropollutants, and its integration with the laccase enzyme immobilized in the MIL-100 metal-organic framework provides a promising approach for new applications in the field of wastewater treatment.