Fate of azo dyes in sludges

Rajagopalan, Gobinath; Boardman, Gregory D.; Michelsen, Donald L.

doi:10.1016/0043-1354(94)90303-4

Cited by 274 publications

(117 citation statements)

References 12 publications

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“…Leurs effets mutagènes, tératogènes ou cancérigènes apparaissent après dégradation de la molécule initiale en sous-produits d'oxydation. Les effets cancérigènes des composés azoïques s'expriment alors, dans certains cas, indirectement par leurs dérivés aminés (BRoWN et De VITo, 1993;CHUNG et al, 1981;GANESH, 1992;IARC, 1982;RAFII et al, 1997). La liaison azo est la partie la plus labile de ces molécules et peut facilement se rompre, chez des organismes mammifères incluant l'homme, sous l'action enzymatique d'une azoréductase P 450 exprimée au niveau du foie (zoLLINGER, 1987) ou d'une azoréductase exprimée par des microorganismes intestinaux strictement anaérobie (CHUNG et al, 1981;RAFII et al, 1997), pour se transformer en composés aminés cancérigènes.…”

Section: Mutagénicité / Carcinogénicitéunclassified

Les colorants textiles sources de contamination de l’eau : CRIBLAGE de la toxicité et des méthodes de traitement

Mansour¹,

Boughzala

Dridi

et al. 2011

rseau

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Les colorants sont largement utilisés dans les imprimeries, les produits alimentaires, cosmétiques et cliniques, mais en particulier dans les industries textiles pour leur stabilité chimique et la facilité de leur synthèse et leur variété de couleurs. Cependant, ces colorants sont à l’origine de la pollution une fois évacués dans l’environnement. La production mondiale des colorants est estimée à plus de 800 000 t•an-1 et les colorants azoïques sont majoritaires et représentent 60-70 %. Compte tenu de la composition très hétérogène de ces derniers, leur dégradation conduit souvent à la conception d’une chaîne de traitement physique-chimique et biologique assurant l’élimination des différents polluants par étapes successives. Dés études ont montré que plusieurs colorants azoïques sont toxiques et mutagènes et le traitement biologique de ces colorants semble présenter un intérêt scientifique majeur. Les traitements physico-chimiques communs (adsorption, coagulation/floculation, précipitation etc.) sont couramment utilisés pour les effluents industriels. Malgré leur rapidité, ces méthodes se sont avérées peu efficaces compte tenu des normes exigées sur ces rejets. Le traitement biologique constitue une alternative fiable; en effet, plusieurs microorganismes sont capables de transformer les colorants azoïques en sous-produits incolores. Les bactéries dégradent les colorants azoïques en deux étapes : un clivage de liaison azo, par l’intermédiaire de l’azoréductase, suivi d’une oxydation des amines aromatiques formées lors de la première étape. L’azoréduction constitue alors une étape clé du traitement des effluents chargés de ces colorants.Dyes are widely used for industrial, printing, food, cosmetic and clinical purposes as well as textile dyeing because of their chemical stability, ease of synthesis, and versatility. Their stability, however, causes pollution once the dyes are released into the environment in effluents. More than 800,000 tons of dyes are annually produced worldwide, of which 60 to 70% are azo dyes. Considering the heterogeneous composition of these latter dyes, their degradation usually requires a chain of physical, chemical and biological treatments assuring the elimination of different pollutants in successive steps. In addition, some azo dyes are toxic and mutagenic and thus the biological treatment of these dyes is now of major scientific interest. Physical-chemical treatments (adsorption, coagulation/flocculation precipitation, etc.) are usually used for industrial effluents. In spite of their rapidity, these methods have turned out to be ineffective in attaining the standards required for these discharges. As a viable alternative, biological processes are receiving increasing interest owing to their cost effectiveness and their ability to produce less sludge. It has been found that some microorganisms can transform azo dyes into colourless products. Bacterial degradation of azo dyes is often initiated by an enzymatic biotransformation step that involves cleavage of azo linkages with the aid of...

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Section: Mutagénicité / Carcinogénicitéunclassified

Les colorants textiles sources de contamination de l’eau : CRIBLAGE de la toxicité et des méthodes de traitement

Mansour¹,

Boughzala

Dridi

et al. 2011

rseau

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“…Correspondingly, the decolorizing efficiency (δ) of ACBK was about 72. 4 2 (the structure was shown in Fig. 1) formed.…”

Section: +mentioning

confidence: 99%

“…Dyestuffs from the textile and photographic industries are becoming a major source of environmental contaminations [2,3]. Some conventional methods such as flocculation, reverse osmosis and activated carbon adsorption have been used to decolorize the textile wastewater [4] Activated carbon adsorption process for the removal of dyes is an accepted practice, but the cost of treatment is high.…”

Section: Introductionmentioning

confidence: 99%

The effects of copper ions on the catalytical degradation of azo dye acid chrome blue K

et al. 2009

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Abstract:The effects of Cu 2+ on the catalytical degradation of acid chrome blue K (ACBK) in UV-TiO 2 and H 2 O 2 processes were studied. In these two processes, Cu 2+ markedly depressed the catalytical degradation of ACBK by its interaction with ACBK. Through this interaction, the new complex Cu(ACBK) 2 formed. The formation of this new complex was favorable to protect some groups in ACBK from the oxidation of reactive oxygen generated in UV-TiO 2 and H 2 O 2 processes, and consequently had suppressing effects on degradation of ACBK. In addition, Cu 2+ also inhibited the degradation of ACBK in UV-TiO 2 process by influencing the adsorption of ACBK on the surface of TiO 2 particles.

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“…Due to the low utilization efficiency, about 2e50% of these dyestuffs are unemployed and exist in the effluent (Ganesh et al, 1994), which is harmful attributed to the apparent color and the toxicity to the organisms (Selvam et al, 2003). The decolorization of azo dyes is a reductive process involved in four electrons transfer for breaking one azo bound (eN]Ne).…”

Section: Introductionmentioning

confidence: 99%

Azo dye decolorization in an up-flow bioelectrochemical reactor with domestic wastewater as a cost-effective yet highly efficient electron donor source

Cui

Gao

et al. 2016

Water Research

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a b s t r a c tA major challenge of employing bioelectrochemical system (BES) for reductively degrading recalcitrant contaminants in industrial wastewater is lacking sufficient electron donors. In this work, domestic wastewater (DW) was demonstrated to efficiently drive BES for implementing the decolorization of azo dye, acid orange 7 (AO7). Side benefit was the simultaneous treatment of DW. Decolorization efficiency in BES fed with DW (R DW ) was found to be comparable with that either fed with glucose (R Glu ) or acetate (R Ac ). Much lower reductant usage ratio was observed in R DW . As a result, when the ratio of electron donors to azo dye decreased to 4.4 mol COD mol À1 AO7, DE of R DW kept over 90% while DEs of R Ac and R Glu were significantly dropped due to the insufficient electrons donation. Besides serving as electron donor, DW was proved to also provide some conductivity and buffer capacity. Accordingly, DE of R DW was less deteriorated when fully removing the external buffer slats. This study comprehensively revealed the feasibility and superiority of DW as a cost-effective electron donor source in BES and brings this technology closer to the practice.

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Fate of azo dyes in sludges

Cited by 274 publications

References 12 publications

Les colorants textiles sources de contamination de l’eau : CRIBLAGE de la toxicité et des méthodes de traitement

Les colorants textiles sources de contamination de l’eau : CRIBLAGE de la toxicité et des méthodes de traitement

The effects of copper ions on the catalytical degradation of azo dye acid chrome blue K

Azo dye decolorization in an up-flow bioelectrochemical reactor with domestic wastewater as a cost-effective yet highly efficient electron donor source

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