Anodic oxidation of wastewater containing the Reactive Orange 16 Dye using heavily boron-doped diamond electrodes

Boron-doped diamond (BDD) films grown on the titanium substrate were used to study the electrochemical degradation of Reactive Orange (RO) 16 Dye. The films were produced by hot filament chemical vapor deposition (HFCVD) technique using two different boron concentrations. The growth parameters were controlled to obtain heavily doped diamond films. They were named as E1 and E2 electrodes, with acceptor concentrations of 4.0 and 8.0 x 10(21) atoms cm(-3), respectively. The boron levels were evaluated from Mott-Schottky plots also corroborated by Raman`s spectra, which characterized the film quality as well as its physical property. Scanning Electron Microscopy showed well-defined microcrystalline grain morphologies with crystal orientation mixtures of (1 1 1) and (1 00). The electrode efficiencies were studied from the advanced oxidation process (AOP) to degrade electrochemically the Reactive Orange 16 azo-dye (RO16). The results were analyzed by UV/VIS spectroscopy, total organic carbon (TOC) and high-performance liquid chromatography (HPLC) techniques. From UV/VIS spectra the highest doped electrode (E2) showed the best efficiency for both, the aromaticity reduction and the azo group fracture. These tendencies were confirmed by the TOC and chromatographic measurements. Besides, the results showed a direct relationship among the BDD morphology, physical property, and its performance during the degradation process. (C) 2011 Elsevier B.V. All rights reserved.

Heterogeneous photocatalytic degradation of reactive dyes in aqueous TiO(2) suspensions: Decolorization kinetics

This work assesses the photocatalytic (TiO(2)/UV) degradation of a simulated reactive dye bath (Black 5, Red 239, Yellow 17, and auxiliary chemicals). Color removal was monitored by spectrophotometry. Mineralization was determined by DOC analyses. Photocatalytic, photolytic, and adsorption experiments were performed, showing that adsorption was negligible. After 30 min of irradiation, it was achieved 97% and 40% of color removal with photocatalysis and photolysis, respectively. No mineralization occurred within 30 min. A kinetic model composed of two, first-order in-series reactions was used. The first photocatalytic decolorization rate constant was k(1) = 2.6 min(-1) and the second k(2) = 0.011 min(-1). The fast decolorization of Reactive Black 5 dye is an indication that the number of azo and vinylsulfone groups in the dye molecule maybe a determining factor for the increased photolytic and photocatalytic color removal and degradation rates. (C) 2008 Elsevier B.V. All rights reserved.

Synthesis and characterization of Fe(III)-doped ceramic membranes of titanium dioxide and its application in photoelectrocatalysis of a textile dye

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Photoeletrolytic system applied to remazol red brilliant degradation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Decolorization of textile dye by Candida albicans isolated from industrial effluents

The aim of the present work was to observe microbial decolorization and biodegradation of the Direct Violet 51 azo dye by Candida albicans isolated from industrial effluents and study the metabolites formed after degradation. C. albicans was used in the removal of the dye in order to further biosorption and biodegradation at different pH values in aqueous solutions. A comparative study of biodegradation analysis was carried out using UV-vis and FTIR spectroscopy, which revealed significant changes in peak positions when compared to the dye spectrum. Theses changes in dye structure appeared after 72 h at pH 2.50; after 240 h at pH 4.50; and after 280 h at pH 6.50, indicating the different by-products formed during the biodegradation process. Hence, the yeast C. albicans was able to remove the color substance, demonstrating a potential enzymatic capacity to modify the chemical structure of pigments found in industrial effluents.

Textile Dye Treated Photoelectrolytically and Monitored by Winogradsky Columns

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ligninolytic activity from newly isolated basidiomycete strains and effect of these enzymes on the azo dye orange II decolourisation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Toxicity assessment and degradation of disperse azo dyes by photoelectrocatalytic oxidation on Ti/TiO2 nanotubular array electrodes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Mutagenic activity removal of selected disperse dye by photoeletrocatalytic treatment

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Simultaneous removal of chromium and leather dye from simulated tannery effluent by photoelectrochemistry

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Assessment of by-products of chlorination and photoelectrocatalytic chlorination of an azo dye

The present work describes a more efficient methodology for the chlorination of water containing disperse dyes, where the chlorinated byproducts identified by mass spectra are compared. this investigation, we tested the degradation of Cl Disperse Blue 291 dye, 2-[(2-Bromo-4,6-dinitrophenyl)azo]-5-(diethylamino)-4-methoxyacetanilide) a commercial azo dye with mutagenic properties. The present work evaluates the photoelectrocatalytic efficiency of removing the Cl Disperse Blue 291 dye from a wastewater of the textile industry. We employed NaCl as a supporting electrolyte. It should be noted that photoelectrocatalytic techniques are non-conventional method of generating chlorine radicals. The by-products formed in this process were analyzed using spectrophotometry, liquid chromatography, dissolved organic carbon, mass spectral analysis and mutagenicity assays. The process efficiency was compared with the conventional chlorination process adopted during sewage and effluents treatment processes. This conventional chlorination process is less efficient in removing color, total organic carbon than the photoelectrochemistry technique. Furthermore, we shall demonstrate that the mutagenicity of the generated by-products obtained using photoelectrocatalysis is completely different from that obtained by the conventional oxidation of chloride ions in the drinking wafer treatment process. (C) 2012 Published by Elsevier B.V.

Evaluation of different electrochemical methods on the oxidation and degradation of Reactive Blue 4 in aqueous solution

The oxidation of a reactive dye, Reactive Blue 4, RB4, (C.I. 61205), widely used in the textile industries to color natural fibers, was studied by electrochemical techniques. The oxidation on glassy carbon electrode and reticulated vitreous carbon electrode occurs in only one step at 2.0 < PH < 12 involving a two-electron transfer to the amine group leading to the imide derivative. Dye solution was not decolorized effectively in this electrolysis process. Nevertheless, the oxidation of this dye on Ti/SnO2/SbOx (3% mol)/RuO2 (1% mol) electrode showed 100% of decolorization and 60% of total organic carbon removal in Na2SO4 0.2 M at PH 2.2 and potential of +2.4 V. Experiments on degradation photoelectrocatalytic were also carried out for RB4 degradation in Na2SO4 0.1 K PH 12, using a Ti/TiO2 photoanode biased at +1.0 V and UV light. After 1 h of electrolysis the results indicated total color removal and 37% of mineralization. (c) 2004 Elsevier Ltd. All rights reserved.

Photoelectrocatalytic degradation of Remazol Brilliant Orange 3R on titanium dioxide thin-film electrodes

Degradation of reactive dye Remazol Brilliant Orange 3R (RBO) has been performed using photoeletrocatalysis. A biased potential is applied across a titanium dioxide thin-film photoelectrode illuminated by UV light. It is suggested that charges photogenerated at the electrode surface give rise to chlorine generation and powerful oxidants (OH) that causes the dye solution to decolorize. Rate constants calculated from color decay versus time reveal a first-order reaction up to 5.0×10-5 mol l-1 in dye concentration. The best experimental conditions were found to be pH 6.0 and 1.0 mol l-1 NaCl when the photoelectrode was biased at +1V (versus SCE). Almost complete mineralization of the dye content (70% TOC reduction) was achieved in a 3-h period using these conditions. Effects of other electrolytes, dye concentration and applied potentials also have been investigated and are discussed. © 2003 Elsevier Science B.V. All rights reserved.

Chlorine disinfection of dye wastewater: Implications for a commercial azo dye mixture

Azo dyes, the most widely used family of synthetic dyes, are often employed as colorants in areas such as textiles, plastics, foods/drugs/cosmetics, and electronics. Following their use in industrial applications, azo dyes have been found in effluents and various receiving waters. Chemical treatment of effluents containing azo dyes includes disinfection using chlorine, which can generate compounds of varying eco/genotoxicity. Among the widely known commercial azo dyes for synthetic fibers is C.I. Disperse Red 1. While this dye is known to exist as a complex mixture, reports of eco/genotoxicity involve the purified form. Bearing in mind the potential for adverse synergistic effects arising from exposures to chemical mixtures, the aim of the present study was to characterize the components of commercial Disperse Red 1 and its chlorine-mediated decoloration products and to evaluate their ecotoxicity and mutagenicity. In conducting the present study, Disperse Red 1 was treated with chlorine gas, and the solution obtained was analyzed with the aid of LC-ESI-MS/MS to identify the components present, and then evaluated for ecotoxicity and mutagenicity, using Daphnia similis and Salmonella/microsome assays, respectively. The results of this study indicated that chlorination of Disperse Red 1 produced four chlorinated aromatic compounds as the main products and that the degradation products were more ecotoxic than the parent dye. These results suggest that a disinfection process using chlorine should be avoided for effluents containing hydrophobic azo dyes such commercial Disperse Red 1. © 2012 Elsevier B.V..

FT-IR analysis of acid black dye biodegradation using saccharomyces cerevisiae immobilized with treated sugarcane bagasse

Textile industries use large amounts of water in dyeing processes and a wide variety of synthetic dyes. A small concentration of these dyes in the environment can generate highly visible pollution and changes in aquatic ecosystems. Adsorption, biosorption, and biodegradation are the most advantageous dye removal processes. Biodegradation occurs when enzymes produced by certain microorganisms are capable of breaking down the dye molecule. To increase the efficiency of these processes, cell immobilization enables the reuse of the immobilized cells and offers a high degree of mechanical strength, allowing metabolic processes to take place under adverse conditions. The aim of the present study was to investigate the use of Saccharomyces cerevisiae immobilized in activated sugarcane bagasse for the degradation of Acid Black 48 dye in aqueous solutions. For such, sugarcane bagasse was treated with polyethyleneimine (PEI). Concentrations of a 1 % S. cerevisiae suspension were evaluated to determine cell immobilization rates. Once immobilization was established, biodegradation assays for 240 h with free and immobilized yeast in PEI-treated sugarcane bagasse were evaluated by Fourier transform infrared spectrophotometry. The results indicated a probable change in the dye molecule and the possible formation of new metabolites. Thus, S. cerevisiae immobilized in sugarcane bagasse is very attractive for biodegradation processes in the treatment of textile effluents. © 2013 Springer Science+Business Media Dordrecht.