Utilization of immobilized horseradish peroxidase for facilitated detoxification of a benzidine based azo dye

• Published in: Chemical engineering research & design 2021-01, Vol.165, p.435-444
• Main Authors: Bayramoglu, Gulay, Akbulut, Aydin, Arica, Mehmet Yakup
• Format: Article
• Language: English
• Subjects: Azo dyes; Biochemistry; Biodegradation; Chlorella; Cryogel; Degradation; Dye; Enzymes; Horseradish peroxidase; Immobilization; Low temperature physics; Peroxidase; Polyhydroxyethyl methacrylate; Reaction time; Stability analysis; Toxicity; Toxicity assessment
• ISSN: 0263-8762; 1744-3563
• DOI: 10.1016/j.cherd.2020.11.017

[Display omitted] •HRP immobilization and degradation of Direct Blue-6 with immobilized HRP were optimized.•Activity of HRP was improved after immobilization on p(HEMA-GMA) cryogel.•More than 94% of Direct Blue 6 degradation was achieved using immobilized HRP.•Toxicity assessment test was realized with D. magna and C. Vulgaris using HRP treated dye solution.•GC–MS data confirmed degradation of Reactive Blue 6 into small molecular weight compounds. Horseradish peroxidase (HRP) was immobilized on the poly(2-hydroxyethyl methacrylate-glycidyl methacrylate) [p(HEMA-GMA)] cryogel and used for the degradation of a benzidine containing azo dye (i.e., Direct Blue-6). The maximum amount of HRP loading was found to be 87.6 mg g−1 cryogel, and the retained immobilized HRP activity was 67% with respect to the same quantity of the free enzyme. Biochemical properties of the HRP preparations were also evaluated along with the stability studied under various denaturizing conditions. The toxicity of the Direct Blue-6 and its degradation products was tested using Daphnia magna. Decrease in the absorbance of the blue color of dye at 590 nm was observed during enzymatic degradation studies. Additionally, Chlorella vulgaris was used as a test organism in the algal growth inhibition studies. After 60 min reaction time, the Direct Blue-6 dye and its degradation product were enzymatically removed from the medium. Thus, after treatment with HRP approximately 60-min, the medium was non-toxic for both D. magna and C. vulgaris. The Direct Blue-6 dye and its degradation product toxicities were reduced after enzymatic treatment from 99.6 to 7.3%. It should be noted that the initial degradation products appeared to be extra toxic compared to the pristine dye.