Localization of the Enzyme System Involved in Anaerobic Reduction of Azo Dyes by Sphingomonas sp. Strain BN6 and Effect of Artificial Redox Mediators on the Rate of Azo Dye Reduction.

Azo dyes are extensively used in the industry, resulting in the large amount of wastewater. Redox mediators (R.M.) can accelerate the chemical reduction of azo dye by shuttling electrons from primary electron donors such as sulfide to azo dyes. Three different types of R.M. were studied on the enhancement of chemical reduction of Acid Orange 7. The electron shuttle ability of these types of R.M. with 2.5 mM of initial sulfide concentration at pH 7.5, either dissolved or undissolved type, followed in order by riboflavin, humic acid and activated carbon. The potential engineering application of these R.M. lie on the superior catalytic ability for riboflavin, wide existence in the environment for humic acid, and retaining in the bioreactors all the times for activated carbon.

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Effect of nitrate on the reduction of Reactive Red 2 by mesophilic anaerobic sludge

Water Science & Technology ◽

10.2166/wst.2008.047 ◽

2008 ◽

Vol 57 (7) ◽

pp. 1067-1071 ◽

Cited By ~ 4

Author(s):

A. B. Dos Santos ◽

C. H. C. Braúna ◽

S. Mota ◽

F. J. Cervantes

Keyword(s):

Azo Dye ◽

Catalytic Properties ◽

Redox Mediator ◽

Anaerobic Sludge ◽

Redox Mediators ◽

Anaerobic Conditions ◽

Anaerobic Reactors ◽

Nitrate Addition ◽

Dye Reduction ◽

Reactive Red 2

This research aimed to evaluate the effect of nitrate on anaerobic azo dye reduction by using mesophilic bioreactors, in the absence (reactor R2) and in the presence (reactor R1) of redox mediators. The azo dye Reactive Red 2 (RR2) and the redox mediator anthraquinone-2,6-disulphonate (AQDS) were selected as model compounds. The results showed that the bioreactors were efficient on RR2 reduction, in which ethanol showed to be a good electron donor to sustain dye reduction under anaerobic conditions. The redox mediator AQDS increased the rates of reductive decolourisation, but its effect was not so remarkable compared to the previous experiments conducted. Contrary to the raised hypothesis that the nitrate addition could decrease decolourisation rates and catalytic properties of the redox mediators, no effect of nitrate was observed in the bioreactors, suggesting that the presence of nitrate in textile wastewaters will not decrease the capacity of anaerobic reactors supplemented or not with redox mediators to decolourize azo dyes.

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Effects of Different Quinoid Redox Mediators on the Anaerobic Reduction of Azo Dyes by Bacteria

Environmental Science & Technology ◽

10.1021/es010227+ ◽

2002 ◽

Vol 36 (7) ◽

pp. 1497-1504 ◽

Cited By ~ 164

Author(s):

Jörg Rau ◽

Hans-Joachim Knackmuss ◽

Andreas Stolz

Keyword(s):

Azo Dyes ◽

Redox Mediators ◽

Anaerobic Reduction

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Use of a sequencing batch biofilter for degradation of azo dyes (acids and bases)

Water Science & Technology ◽

10.2166/wst.2000.0532 ◽

2000 ◽

Vol 42 (5-6) ◽

pp. 329-336 ◽

Cited By ~ 8

Author(s):

M. Quezada ◽

I. Linares ◽

G. Buitrón

Keyword(s):

Azo Dyes ◽

Azo Dye ◽

Degradation Rate ◽

Removal Rate ◽

Textile Effluent ◽

Colour Removal ◽

Substrate Degradation ◽

Acids And Bases ◽

Removal Efficiencies ◽

Basic Red 46

The degradation of azo dyes in an aerobic biofilter operated in an SBR system was studied. The azo dyes studied were Acid Red 151 and a textile effluent containing basic dyes (Basic Blue 41, Basic Red 46 and 16 and Basic Yellow 28 and 19). In the case of Acid Red 151 a maximal substrate degradation rate of 288 mg AR 151/lliquid·d was obtained and degradation efficiencies were between 60 and 99%. Mineralization studies showed that 73% (as carbon) of the initial azo dye was transformed to CO2 by the consortia. The textile effluent was efficiently biodegraded by the reactor. A maximal removal rate of 2.3 kg COD/lliquid·d was obtained with removal efficiencies (as COD) varying from 76 to 97%. In all the cycles the system presented 80% of colour removal.

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Effect of Photo-Isomerization of Azo Dyes on the Photonic Bandgap in Chiral Nematics

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.181-182.257 ◽

2011 ◽

Vol 181-182 ◽

pp. 257-260

Author(s):

David Statman ◽

Andrew Jockers ◽

Daniel Brennan

Keyword(s):

Liquid Crystal ◽

Liquid Crystals ◽

Azo Dyes ◽

Azo Dye ◽

Photonic Bandgap ◽

Methyl Red ◽

Central Wavelength ◽

Chiral Nematic ◽

Anchoring Energy ◽

Pitch Length

Chiral nematic liquid crystals prepared with Grandjean texture demonstrate a photonic bandgap whose central wavelength is proportional to the pitch length, P, of the liquid crystal and whose width is given by (ne – no)P. We show that methyl red doped chiral nematics undergo a shift in the photonic bandgap upon photo-isomerization. This shift is a result of (1) photo-induced change in anchoring energy on the nematic surface, and (2) change in the natural pitch length from the photo-isomerization of the azo dye.

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The contribution of fermentative bacteria and methanogenic archaea to azo dye reduction by a thermophilic anaerobic consortium

Enzyme and Microbial Technology ◽

10.1016/j.enzmictec.2005.09.003 ◽

2006 ◽

Vol 39 (1) ◽

pp. 38-46 ◽

Cited By ~ 54

Author(s):

André B. dos Santos ◽

Marta P. de Madrid ◽

Frank A.M. de Bok ◽

Alfons J.M. Stams ◽

Jules B. van Lier ◽

...

Keyword(s):

Azo Dye ◽

Methanogenic Archaea ◽

Fermentative Bacteria ◽

Dye Reduction ◽

Anaerobic Consortium

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The contribution of biotic and abiotic processes during azo dye reduction in anaerobic sludge

Water Research ◽

10.1016/s0043-1354(03)00166-0 ◽

2003 ◽

Vol 37 (13) ◽

pp. 3098-3109 ◽

Cited By ~ 62

Author(s):

Frank P van der Zee ◽

Iemke A.E Bisschops ◽

Valérie G Blanchard ◽

Renske H.M Bouwman ◽

Gatze Lettinga ◽

...

Keyword(s):

Azo Dye ◽

Anaerobic Sludge ◽

Dye Reduction

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Biodegradation of selected azo dyes under methanogenic conditions

Water Science & Technology ◽

10.2166/wst.1997.0576 ◽

1997 ◽

Vol 36 (6-7) ◽

pp. 65-72 ◽

Cited By ~ 35

Author(s):

Elías Razo-Flores ◽

Maurice Luijten ◽

Brian Donlon ◽

Gatze Lettinga ◽

Jim Field

Keyword(s):

Azo Dyes ◽

Textile Industry ◽

Azo Dye ◽

Biological Treatment ◽

Present Report ◽

Anaerobic Bacteria ◽

Aminosalicylic Acid ◽

Batch Experiments ◽

Azo Reduction ◽

Uasb Reactors

Biological treatment of wastewaters discharged by the textile industry could potentially be problematic due to the high toxicity and recalcitrance of the commonly-used azo dye compounds. In the present report, the fate of two azo dyes under methanogenic conditions was studied. Mordant Orange 1 (MO1) and Azodisalicylate (ADS) were completely reduced and decolorised in continuous UASB reactors in the presence of cosubstrates. In the MO1 reactor, both 5-aminosalicylic acid (5-ASA) and 1,4-phenylenediamine were identified as products of azo cleavage. After long adaptation periods, 5-ASA was detected at trace levels, indicating further mineralization. ADS, a pharmaceutical azo dye constructed from two 5-ASA units, was completely mineralized even in the absence of cosubstrate, indicating that the metabolism of 5-ASA could provide the reducing equivalents needed for the azo reduction. Batch experiments confirmed the ADS mineralization. These results demonstrate that some azo dyes could serve as a carbon, energy, and nitrogen source for anaerobic bacteria.

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Development of novel pH-sensitive azo dyes from Cardanol as a bioresource

Pigment & Resin Technology ◽

10.1108/prt-03-2020-0026 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Siddhesh Umesh Mestry ◽

Umesh Ratan Mahajan ◽

Aswathy M. ◽

Shashank T. Mhaske

Keyword(s):

Azo Dyes ◽

Azo Dye ◽

Density Functional ◽

Ph Sensitivity ◽

Water Soluble ◽

Hydroxyl Group ◽

Disulfonic Acid ◽

Colour Properties ◽

Content Type ◽

Good Thermal Stability

Purpose The purpose of this paper is to use the bio-based resource as the starting material for the synthesis of azo dye. Cardanol is one of the most used bio-based resources for carrying out the synthesis of various compounds having numerous end applications. The study presents an attempt to develop an azo dye from Cardanol having end applications in pH-responsive dyes. Design/methodology/approach The cardanol was sulfonated to block the para position by which ortho positioned hydroxyl group after diazotization and coupling will provide necessary pH-sensitivity. The diazotization of two naphthalene derivatives, i.e. 1-naphthol-8-amino-3,6-disulfonic acid (H-acid) and 7-amino-4-hydroxy-2-naphthalene sulfonic acid (J-acid) was carried out using the standard practice, and the diazotized compounds were coupled with the sulfonated cardanol. The obtained dyes were characterized by Fourier transform infrared, nuclear magnetic resonance, carbon-hydrogen-nitrogen-sulfur analysis and hydroxyl value. The colour properties were checked using UV-vis spectrophotometry and density functional theory, while thermogravimetric analysis was used for the thermal degradation studies of both the dyes. Findings Water-soluble cardanol-based azo dyes were prepared successfully having good thermal stability, and the obtained results are being presented in this paper. Originality/value The originality lies between the use of cardanol as a bio-based resource for the synthesis of azo-dye and the obtained azo-dye has the pH-sensitivity.

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