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High cost and low operational stability are the most important challenges limiting the possible use of laccase in the removal of textile dyes. To overcome these challenges, in this study, polyvinylpyrrolidone (PVP)-coated magnetic nanoparticles (MNPs) were produced and characterized. To our knowledge, this is the first study to explore the feasibility of immobilizing a Trametes trogii laccase enzyme on Fe3O4/PVP MNPs. The characterization of samples and the successful immobilization of laccase were verified by characterization methods. Besides, the biochemical properties and stability of the Fe3O4/PVP/Lac were evaluated in terms of optimum pH, optimum temperature, thermostability, thermodynamic and kinetic parameters, storage stability, operational stability, and decolorization efficiency of two different textile dyes. The optimum activities were recorded at pH 2.5 °C and 30 °C. The Fe3O4/PVP/Lac displayed remarkable thermal stability and activation energy for denaturation, enthalpy, Gibbs free energy, and entropy results confirmed the enhanced stability of Fe3O4/PVP/Lac against high temperatures. Meanwhile, the Fe3O4/PVP/Lac retained about 58% of its original activity after seven consecutive reuses, while it retained up to 25% of its original activity after 28 d of storage at room temperature. Km and Vmax for the Fe3O4/PVP/Lac were calculated to be 126 µM and 211 µmol/min, respectively. Finally, after 8 and 6 cycles of repeated use, the Fe3O4/PVP/Lac still decolorized 32.34% and 32.23% of Remazol Brilliant Blue R (RBBR) and Indigo Carmine (IC), respectively. As envisioned, this study suggests a promising way to solve the problems of high price and poor operational stability of the enzyme during biocatalytic decolorization of textile dyes in wastewaters. [ABSTRACT FROM AUTHOR]

The present study aimed to immobilize laccase on dry bacterial cellulose (BC) produced by Komagataeibacter xylinus B759 in mulberry pomace waste extract as a low‐cost and natural waste by‐product and to determine the effectiveness of the obtained laccase immobilized BC (Lac/BC) for textile dye decolorization. The highest BC yield obtained after optimization studies was as 1.70 g/L in pH 8.0 medium at 32°C after 15 days. BC and Lac/BC structures were characterized by different instrumental techniques. A transition to more amorphous character was observed with the binding of the enzyme structure. The morphological properties and fiber structure of the BC and enzyme‐linked cellulose structures were examined by SEM and AFM analyses. Obtained Lac/BC pieces were used for the decolorization of Reactive Blue 171 (RB 171) and Reactive Blue 198 (RB 198) diazo dyes during the repeated‐batch process. As a result of using 12 pieces of Lac/BC, 93% and 98% decolorization values were obtained for the RB 171 and RB 198 dyes in the first use, while the color removal was still 83% and 51% at the 8th use, respectively. The results showed that BC produced in a mulberry pomace waste extract can be used for laccase immobilization and Lac/BC is an effective and promising system for textile dye decolorization. [ABSTRACT FROM AUTHOR]