Date of Award

2023

Publication Type

Thesis

Degree Name

M.A.Sc.

Department

Civil and Environmental Engineering

Keywords

Hydrogen peroxide, Reactive black 5, Soybean peroxidase, Azo dyes, Physiochemical treatment

Supervisor

K.E.Taylor

Supervisor

I.Xu

Rights

info:eu-repo/semantics/openAccess

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

The textile industry and other colour-oriented industries utilize azo dyes in extensive amounts. Dye effluents are recalcitrant to natural biodegradation, hence, causing toxic effects on the environment. Physiochemical treatment generates sludge which requires secondary disposal; advanced oxidation processes (AOPs) are cost and energy intensive; biological methods like anaerobic treatment via bacteria generate aromatic amines which are mutagenic and carcinogenic. A promising alternative that has shown great success in the treatment of wastewater is the enzymatic method. This thesis reports the enzymatic degradation of Reactive Black 5 (RB5), Acid Orange 7 (AO7), and Acid Orange 20 (AO20) from synthetic textile effluents using soybean peroxidase (SBP). ‘Synthetic textile effluents’ refers to the contamination of water by the applied dye. Dyes were individually tested at a constant dye concentration of 50 μM considering the following parameters: pH, SBP, and hydrogen peroxide, for 3 hours and subsequently analyzed using UV-VIS spectrometer and high-performance liquid chromatography (HPLC). Optimization was done using a one-factor-at-a-time approach. It should be mentioned that ≥95% removal efficiency was obtained within 5 minutes of reaction at optimal conditions of pH 3.5, 0.075 U/mL SBP, and 0.0375 mM hydrogen peroxide for RB5; pH 3.0, 0.5 U/mL SBP, and 0.0375 mM hydrogen peroxide for RB5; and pH 3.0, 0.0025 U/mL SBP, and 0.0625 mM hydrogen peroxide for AO20. A pro-forma cost analysis for the feasibility of commercializing enzymatic treatment in comparison to other conventional treatment methods showed that the total estimated cost of enzymatic treatment of the investigated dyes was nearly 2 to 9 times less than that of the conventional treatments. This study verifies the viability of using SBP for the sulfonated azo dyes treatment in the order of increasing cost of treatment as AO20

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