Degradation of Azo Dyes by Laccase and Ultrasound Treatment

Abstract

The goal of this work was to investigate the decomposition of azo dyes by oxidative methods, such as laccase and ultrasound treatments. Each of these methods has strong and feeble sides. The laccase treatment showed high decolorization rates but cannot degrade all investigated dyes (reactive dyes), and high anionic strength led to enzyme deactivation. Ultrasound treatment can decolorize all tested dyes after 3 h at a high energy input, and prolonged sonication leads to nontoxic ionic species, which was demonstrated by ion chromatography and toxicity assays. For the first time, it was shown that a combination of laccase and ultrasound treatments can have synergistic effects, which was shown by higher degradation rates. Bulk light absorption and ion-pairing high-performance liquid chromatography (IP-HPLC) were used for process monitoring, while with reversedphase HPLC, a lower number of intermediates than expected by IP-HPLC was found. Liquid chromatographymass spectrometry indicated that both acid orange dyes lead to a common end product due to laccase treatment. Acid Orange 52 is demethylated by laccase and ultrasound treatment. Further results confirmed that the main effect of ultrasound is based on˙OH attack on the dye molecules.

Bacterial diversity and composition in major fresh produce growing soils affected by physiochemical properties and geographic locations

“…Specific features that contribute to mutagenicity of azo dyes are related to differences in substitution sites, and the number and position of hydroxyl and sulpho groups adjacent to the azo bond (Table 1). For example, dyes containing a hydroxyl group at the ortho position are more toxic than those containing a hydroxyl group at the para position (Tauber et al, 2005). Likewise, differences in biodegradability are associated with particular features.…”

Degradation of the synthetic dye amaranth by the fungus Bjerkandera adusta Dec 1: inference of the degradation pathway from an analysis of decolorized products

“…Moreover, degradation of azo dyes by reduction in water produces several aromatic amines, which are more toxic and carcinogenic than are the dyes themselves. The permissible concentration of aromatic amines in waste water is regulated by legislation, especially in developed countries (Tauber et al 2005). Aromatic amines enter the human body through the environmental chain and are next converted to acyloxyamine derivatives.…”

Degradation of Azo Dyes by Trametes villosa Laccase over Long Periods of Oxidative Conditions

“…It is known that laccases can catalyze the polymerization of various halogen-, alkyl-, and alkoxy-substituted anilines (15). In the literature, there is a large number of papers reporting on the decolorization of azo dyes; however, the fate of the products of azo dye laccase reactions and their possible polymerization have been ignored (7,16,25,28). Therefore, the purpose of this work was the study of azo dye degradation products in the presence of laccase.…”