title: Degradation of azo dyes by oxidative processes--laccase and ultrasound treatment.
abstract: Azo dyes are of synthetic origin and their environmental fate is not well understood. They are resistant to direct aerobic bacterial degradation and form potentially carcinogenic aromatic amines by reduction of the azo group. This study shows that applying the oxidative processes of enzymatic treatment with laccase and ultrasound treatment, both alone and in combination, leads to dye degradation. Laccase treatment degraded both Acid Orange and Direct Blue dyes within 1-5 h but failed in the case of Reactive dyes, whereas ultrasound degraded all the dyes investigated (3-15 h). When applied as multi-stage combinations the treatments showed synergistic effects for dye degradation compared with individual treatments. Bulk light absorption (UV-Vis) and ion pairing HPLC were used for process monitoring. Additionally, mass spectrometry was used to elucidate the structures of intermediates arising from ultrasound treatment.
authors.affiliation: University of Applied Sciences Cologne, Faculty of Process Engineering, Energy and Mechanical Systems, Department of Chemical Engineering and Plant Design, D-50679 Cologne, Germany.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Tauber
authors.forename: Georg M
authors.initials: GM
authors.lastname: Gübitz
authors.forename: Astrid
authors.initials: A
authors.lastname: Rehorek
mesh_terms: D001391:Azo Compounds / Q000032:analysis* / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004396:Coloring Agents / Q000494:pharmacology; D005505:Food Coloring Agents / Q000032:analysis*; D007700:Kinetics; D042845:Laccase / Q000737:chemistry*; D013058:Mass Spectrometry / Q000379:methods; D008956:Models, Chemical; D010100:Oxygen / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013997:Time Factors; D014465:Ultrasonics; D014466:Ultraviolet Rays
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D005505:Food Coloring Agents; C100258:methyl orange; D042845:Laccase; C408744:Direct Blue 71; D010100:Oxygen