Improvement of Laccase Activity Via Covalent Immobilization over Mesoporous Silica Coated Magnetic Multiwalled Carbon Nanotubes for the Discoloration of Synthetic Dyes

Abstract

Due to its environmental friendliness and biodegradable ability, the enzymatic decolorization of azo dyes is the best option. However, the free enzyme suffers from various limitations, including poor stability, no repeatable use, and a high expense, which is the key drawback for its practical use. In this analysis, the laccase enzyme was immobilized in mesoporous silica coated magnetic multiwalled carbon nanotubes (Fe 3 O 4 -MWCNTs@SiO 2 ) by a glutaraldehyde cross-linker to create an easily separable and stable enzyme. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive Xray spectroscopy (EDX) were used to characterize the as-synthesized Fe 3 O 4 -MWCNTs@SiO 2 . Laccase immobilized in Fe 3 O 4 -MWCNTs@SiO 2 showed a good improvement in temperature, pH, and storage stability. Moreover, the operational stability of the biocatalyst was improved, retaining 87% of its original activity even after 10 cycles of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) oxidation. The biocatalysts were applied for the decolorization of selected azo dyes without a mediator, and up to 99% of Eriochrome Black T (EBT), 98% of Acid Red 88 (AR 88), and 66% of Reactive Black 5 (RB5) were decolorized. Based on these properties, the biocatalysts can be potentially utilized in various environmental and industrial applications.

Catalytic and Physicochemical Evaluation of a TiO2/ZnO/Laccase Biocatalytic System: Application in the Decolorization of Azo and Anthraquinone Dyes

“…Furthermore, the efficiency of the removal of C.I. Reactive Black 5 varied depending on the support used: TiO 2 /ZrO 2 (15%), Fe 3 O 4 -MWCNT@SiO 2 (80%), magnetic chitosan nanoparticles (90%), Fe 3 O 4 -NH 2 @MIL-101 (Cr) (65%) [39,[50][51][52][53]. It is noteworthy that the biocatalytic system presented in this study also removed C.I.…”

Functional Nanohybrids and Nanocomposites Development for the Removal of Environmental Pollutants and Bioremediation

“…An example is represented by mesoporous silica-coated magnetic multiwalled carbon nanotubes (Fe 3 O 4 -MWCNTs@SiO 2 ) used for the immobilization of the laccase enzyme with glutaraldehyde as a cross-linker, to serve as a biocatalyst for the discoloration of synthetic organic dyes. In particular, this biocatalyst has been tested for the discoloration of Eriochrome Black T, Acid Red 88, and Reactive Black 5, without a mediator, showing a decolorization efficiency up to 99, 98 and 66%, respectively, and also for the oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), retaining 87% of its original activity even after 10 cycles of use [ 156 ].…”

Synthesis of lipase-hydrogel microspheres and their application in deacidification of high-acid rice bran oil

“…After being incubated in sodium phosphate citrate buffer (pH = 6) at different temperatures (30,40,50,60, 70 and 80 1C) for 2 h respectively. The reusability of L-PHAMs was evaluated by measuring the enzymatic activity after each catalysis.…”