Sustainable Development of Magnetic Chitosan Core–Shell Network for the Removal of Organic Dyes from Aqueous Solutions

The wide use of alizarin red S (ARS), a typical anthraquinone dye, has led to its continued accumulation in the aquatic environment, which causes mutagenic and carcinogenic effects on organisms. Therefore, this study focused on the removal of ARS dye by adsorption onto a magnetic chitosan core–shell network (MCN). The successful synthesis of the MCN was confirmed by ATR-FTIR, SEM, and EDX analysis. The influence of several parameters on the removal of ARS dye by the MCN revealed that the adsorption process reached equilibrium after 60 min, pH played a major role, and electrostatic interactions dominated for the ARS dye removal under acidic conditions. The adsorption data were described well by the Langmuir isotherm and a pseudo-second order kinetic model. In addition to the preferable adsorption of hydrophobic dissolved organic matter (DOM) fractions onto the MCN, the electrostatic repulsive forces between the previously adsorbed DOM onto MCN and ARS dye resulted in lower ARS dye removal. Furthermore, the MCN could easily be regenerated and reused for up to at least five cycles with more than 70% of its original efficiency. Most importantly, the spent MCN was pyrolytically converted into N-doped magnetic carbon and used as an adsorbent for various dyes, thus establishing a waste-free adsorption process.

Optimization of Anthraquinone Dye Wastewater Treatment using Ozone in the Presence of Persulfate Ion in a Semi-batch Reactor

The degradation of anthraquinone dye Reactive Blue 19 by using O3 and O3 / S2O8 2- in the advanced oxidation processes is studied to investigate the performance of these two systems. The response surface method with a Box-behnken Design was successfully applied to identify the relationship between operating variables such as initial concentration, S2O8 2- dosage and contact time in order to determine the optimum operating condition. The quadratic model for the percentage COD removal (response) proved to be significant for the degradation of the dye. The COD removal efficiency under Box-behnken Design and experimental test were found to be 96.2% and 83.9% under the optimum conditions. Furthermore, the result obtained showed that the O3 / S2O8 2- system is more effective than the O3 only in treating the Reactive Blue 19.

Decolorization Assay of the Anthraquinone Dye Acid Blue 25 by Trichoderma asperellum LBKURCC1 Crude Laccase Extracts

One major concern of the textile industry waste is the health hazard imposed by textile dye waste effluents. Anthraquinone dyes are the second largest group of dyes produced and used annually worldwide, that is difficult to degrade naturally. Biological methods using enzymes for waste treatment is gaining popularity due to its eco-friendliness. Laccase is an enzyme with potential to degrade textile dyes, due to its wide ability to oxidize a wide range of substrates. The aim of this study was to evaluate the ability of T. asperellum LBKURCC1 laccase crude extract to decolorize the anthraquinone anionic dye Acid Blue 25 (AB25). A solution of 50 ppm AB25, pH 5.5, was treated with T. asperellum LBKURCC1 laccase crude extract and incubated at room temperature. Absorbance of the solution at 603 nm was measured daily and compared to buffer and heat denatured enzyme controls. No decolorization of AB25 was observed up to 6 days incubation in the enzyme treated samples, as well as the controls. Addition of 0.1 to 5 mM of 1-hydroxybenzotriazole hydrate (HBT) to the decolorization assay did not succeed in mediating the redox reaction of AB25 oxidation by the T. asperellum LBKURCC1 laccase.

Amended Safety Assessment of Acid Violet 43 as Used in Cosmetics

The Expert Panel for Cosmetic Ingredient Safety (Panel) reopened the safety assessment of Acid Violet 43, a cosmetic ingredient that is an anthraquinone dye reported to function in cosmetics as a colorant. This colorant has the same chemical structure as Ext. D&C Violet No. 2, which is a certified colorant; however, Acid Violet 43 is not a certified color and it could have impurities that are not allowed in the certified color. The Panel reviewed relevant new data related to this ingredient and concluded that Acid Violet 43 is safe in the present practices of use and concentration for use in hair dye formulations. This conclusion supersedes the previous conclusion for Acid Violet 43 that included impurity specifications indicated for the certified color.

Efficient Degradation of Zearalenone by Dye-Decolorizing Peroxidase from Streptomyces thermocarboxydus Combining Catalytic Properties of Manganese Peroxidase and Laccase

Ligninolytic enzymes, including laccase, manganese peroxidase, and dye-decolorizing peroxidase (DyP), have attracted much attention in the degradation of mycotoxins. Among these enzymes, the possible degradation pathway of mycotoxins catalyzed by DyP is not yet clear. Herein, a DyP-encoding gene, StDyP, from Streptomyces thermocarboxydus 41291 was identified, cloned, and expressed in Escherichia coli BL21/pG-Tf2. The recombinant StDyP was capable of catalyzing the oxidation of the peroxidase substrate 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), phenolic lignin compounds 2,6-dimethylphenol, and guaiacol, non-phenolic lignin compound veratryl alcohol, Mn2+, as well as anthraquinone dye reactive blue 19. Moreover, StDyP was able to slightly degrade zearalenone (ZEN). Most importantly, we found that StDyP combined the catalytic properties of manganese peroxidase and laccase, and could significantly accelerate the enzymatic degradation of ZEN in the presence of their corresponding substrates Mn2+ and 1-hydroxybenzotriazole. Furthermore, the biological toxicities of the main degradation products 15-OH-ZEN and 13-OH-ZEN-quinone might be remarkably removed. These findings suggested that DyP might be a promising candidate for the efficient degradation of mycotoxins in food and feed.

Enzymatic Degradation of Multiple Major Mycotoxins by Dye-Decolorizing Peroxidase from Bacillus subtilis

The co-occurrence of multiple mycotoxins, including aflatoxin B1 (AFB1), zearalenone (ZEN) and deoxynivalenol (DON), widely exists in cereal-based animal feed and food. At present, most reported mycotoxins degrading enzymes target only a certain type of mycotoxins. Therefore, it is of great significance for mining enzymes involved in the simultaneous degradation of different types of mycotoxins. In this study, a dye-decolorizing peroxidase-encoding gene BsDyP from Bacillus subtilis SCK6 was cloned and expressed in Escherichia coli BL21/pG-Tf2. The purified recombinant BsDyP was capable of oxidizing various substrates, including lignin phenolic model compounds 2,6-dimethylphenol and guaiacol, the substrate 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid), anthraquinone dye reactive blue 19 and azo dye reactive black 5, as well as Mn2+. In addition, BsDyP could efficiently degrade different types of mycotoxins, including AFB1, ZEN and DON, in presence of Mn2+. More important, the toxicities of their corresponding enzymatic degradation products AFB1-diol, 15-OH-ZEN and C15H18O8 were significantly lower than AFB1, ZEN and DON. In summary, these results proved that BsDyP was a promising candidate for the simultaneous degradation of multiple mycotoxins in animal feed and food.

The Mechanism of Degradation of Alizarin Red by a White-Rot Fungus (Lenzites Gibbosa)

Background Alizarin red (AR) is a typical anthraquinone dye, and the resulting wastewater is toxic and difficult to remove. A study showed that the white rot fungus Lenzites gibbosa (L. gibbosa) can degrade dye wastewater by decolorization and has evolved its own enzyme-producing traits. Methods In this study, transcriptome sequencing was performed after alizarin red treatment for 0, 3, 7, 10, and 14 h. The key pathways and key enzymes involved in alizarin red degradation were found to be though the analysis of KEGG, GO and COG. The GST, MnP and Laccase enzyme activities of L. gibbosa treated with alizarin red for 0–14 h were detected. LC-MS and GC-MS analyses of alizarin red decomposition products after 7 h and 14 h were performed. Results The glutathione metabolic pathway ko00480, and the key enzymes GST, MnP, Laccase and CYP450 were selected. Most of the genes encoding these enzymes were upregulated under alizarin red conditions. The GST activity increased 1.8 times from 117.55 U/mg prot at 0 h to 217.03 U/mg prot at 14 h. The MnP activity increased 2.9 times from 6.45 U/L to 18.55U/L. The Laccase activity increased 3.7 times from 7.22 U/L to 27.28 U/L. Analysis of the alizarin red decolourization rate showed that the decolourization rate at 14 h reached 20.21%. The main degradation intermediates were found to be 1,4-butene diacid, phthalic acid, 1,1-diphenylethylene, 9,10-dihydroanthracene, 1,2-naphthalene dicarboxylic acid, bisphenol, benzophenol-5,2-butene, acrylaldehyde, and 1-butylene, and the degradation process of AR was inferred. Overall, 1,4-butene diacid is the most important intermediate product produced by AR degradation. Conclusions The glutathione metabolic pathway was the key pathway for AR degradation. GST, MnP, Laccase and CYP450 were the key enzymes for AR degradation. 1,4-butene diacid is the most important intermediate product. This study explored the process of AR biodegradation at the molecular and biochemical levels and provided a theoretical basis for its application in practical production.