Horseradish Peroxidase-Catalyzed Degradation of Reactive Blue 171 Dye

Abstract

Despite establishing covalent bonds with cellulose, significant amounts of reactive dyes remain unfixed and are lost through secondary reactions during cellulosic fiber dyeing, ultimately entering textile wastewater and making additional treatment necessary. In this work, the kinetics of the biocatalytic degradation of the textile dye Reactive Blue 171 with horseradish peroxidase (HRP PeO 906) with an activity of 2009.2 kU/g was studied. The influence of temperature (in the range of 30-70 °C), pH (in the range of 4-8), the amount of biocatalyst (1, 2, and 3 mg), and hydrogen peroxide concentration (up to 0.3%) used in the process was evaluated. Biodegradation was monitored by the disappearance of the maximum absorption band of the dye at 625 nm. Biodegradation of Reactive Blue 171 followed first-order kinetics with rate constants ranging from 1.538 × 10^-2 min^-1 (30 °C) to 7.514 × 10^-2 min^-1 (70 °C) and R ² ≥ 0.998. The best result observed for the biodegradation of Reactive Blue 171 was obtained at 40 °C when 0.1 g L^-1 of dye, 3 mg of enzyme, and 0.3% H₂O₂ were used. Under these conditions activation parameters were determined as E _a = 13.24 kJ mol^-1(r ² = 0.9919), ΔH ^# = 10.55 kJ mol^-1 (r ² = 0.9717), ΔG ^# _medium = 14.09 kJ mol^-1, and ΔS ^# _medium = 0.109 kJ K^-1 mol^-1, achieving a decolorization of 81.40% after 120 min. Biodegradation involved low energy variation and was favored by increases in temperature and biocatalyst concentration. In the investigated pH range, the highest dye degradation was observed at pH 4 and 5. The obtained decolorization results of Reactive Blue 171 with HRP and H₂O₂ indicate that the biodegradation of textile dyes is a viable and sustainable method.

1

Structure of the dye C.I. Reactive Blue 171.

2

Decrease in the absorption band of Reactive Blue 171 dye catalyzed by HRP PeO 906 peroxidase as a function of time at 50 °C, with [dye] = 0.1 g L^–1, [H₂O₂] = 0.3% (1 mL), and [enzyme] = 3 mg.

3

Decolorization of Reactive Blue 171 dye solution with 1 mg of HPR PeO 906 at different temperatures: (■) = 70 °C only in the presence of H₂O₂; (●) = 30 °C; (▲) = 40 °C; (▼) = 50 °C; (◆) = 60 °C; (◀) = 70 °C; [H₂O₂] = 0.3% and [dye] = 0.1 g L^–1.

4

Kinetic curve of decolorization of Reactive Blue 171 solution with 1 mg of HRP PeO 906 at different temperatures: (■) = 30 °C; (●) = 40 °C; (▲) = 50 °C; (▼) = 60 °C; (◀) = 70 °C; [H₂O₂] = 0.3% and [dye] = 0.1 g L^–1.

5

Kinetic curve of Reactive Blue 171 dye decolorization with 2 mg of HRP PeO 906 at different temperatures: (■) = 30 °C; (●) = 40 °C; (▲) = 50 °C; (▼) = 60 °C; (◀) = 70 °C; [H₂O₂] = 0.3% and [dye] = 0.1 g L^–1.

6

Kinetic curve of Reactive Blue 171 dye decolorization with 3 mg of HRP PeO 906 at different temperatures: (■) = 30 °C; (●) = 40 °C; (▲) = 50 °C; (▼) = 60 °C; (◀) = 70 °C; [H₂O₂] = 0.3% and [dye] = 0.1 g L^–1.

7

Decolorization of 0.1 g L^–1 Reactive Blue 171 solution with 1 mg of HRP PeO 906 and 0.03% H₂O₂ at 40 °C under different pH values: (■) = pH 4; (●) = pH 5; (▲) = pH 6; (▼) = pH 7; (◆) = pH 8; [H₂O₂] = 0.03% and [dye] = 0.1 g L^–1.

8

Decolorization of 0.1 g L^–1 Reactive Blue 171 solution with 2 mg of HRP PeO 906 and 0.03% H₂O₂ at 40 °C at different pH values: (■) = pH 4; (●) = pH 5; (▲) = pH 6; (▼) = pH 7; (◆) = pH 8; [H₂O₂] = 0.03% and [dye] = 0.1 g L^–1.

9

Decolorization of 0.1 g L^–1 Reactive Blue 171 solution with 3 mg of HRP PeO 906 and 0.03% H₂O₂ at 40 °C at different pH values: (■) = pH 4; (●) = pH 5; (▲) = pH 6; (▼) = pH 7; (◆) = pH 8; [H₂O₂] = 0.03% and [dye] = 0.1 g L^–1.