Journal articles: 'Azo dyes – Environmental aspects'

1

Yoo, E. S., J. Libra, and U. Wiesmann. "Reduction of azo dyes by desulfovibrio desulfuricans." Water Science and Technology 41, no. 12 (June 1, 2000): 15–22. http://dx.doi.org/10.2166/wst.2000.0231.

Full text

Abstract:

Azo dyes are widely used in textile finishing, and have become of concern in wastewater treatment because of their color, bio-recalcitrance, and potential toxicity to animals and humans. Thus, wastewater with azo dyes must be decolorized and furthermore mineralized in appropriate systems combining biological and chemical processes. In this study, the potential for sulfate reducing bacteria (SRB) to decolorize azo dyes was studied, employing the pure culture of Desulfovibrio desulfuricans (D. desulfuricans) with varying sulfate levels. Under sulfate-rich conditions, the sulfide produced from sulfate respiration with pyruvate (electron donor) by D. desulfuricans chemically decolorized the azo dyes C. I. Reactive Orange 96 (RO 96) and C. I. Reactive Red 120 (RR 120). Under sulfate-depleted conditions (≤0.1 mmol/L), the decolorization of RO 96 and RR 120 occurred in correlation with the fermentation of pyruvate by D. desulfuricans. It is suggested that the electrons liberated from the pyruvate oxidation were transferred via enzymes and/or coenzymes (electron carriers) to the dyes as alternative terminal electron acceptors, giving rise to decolorization, instead of to the protons (H+), resulting in the production of H2. Both decolorization pathways were compared in light of bioenergetics and engineering aspects.

APA, Harvard, Vancouver, ISO, and other styles

2

Cervantes, Francisco J., and André B. Dos Santos. "Reduction of azo dyes by anaerobic bacteria: microbiological and biochemical aspects." Reviews in Environmental Science and Bio/Technology 10, no. 2 (January 19, 2011): 125–37. http://dx.doi.org/10.1007/s11157-011-9228-9.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Encinas-Yocupicio, A. A., E. Razo-Flores, F. Sánchez-Díaz, A. B. dos Santos, J. A. Field, and F. J. Cervantes. "Catalytic effects of different redox mediators on the reductive decolorization of azo dyes." Water Science and Technology 54, no. 2 (July 1, 2006): 165–70. http://dx.doi.org/10.2166/wst.2006.500.

Full text

Abstract:

The catalytic effects of redox mediators, with distinct standard redox potentials (E′0), were evaluated on the first-order rate constant of decolorization (Kd) of recalcitrant azo dyes by an anaerobic granular sludge. The dyes studied included mono-azo (Reactive Orange 14, RO14), di-azo (Direct Blue 53, DB53), and tri-azo (Direct Blue 71, DB71) compounds. Toxicity and auto-catalytic aspects seemed to play a role in determining the rate of decolorization. Addition of riboflavin, anthraquinone-2,6-disulphonate (AQDS) or lawsone as a redox mediator, increased the Kd value for all dyes studied, although their impact varied in every case. Kd values were increased from 1.1-fold up to 3.8-fold depending on the redox mediator applied. Moreover, catalysts with moderately similar E′0 value caused distinct stimulation on the rate of decolorization. These results should be considered for selecting the proper redox mediator to be applied during the anaerobic treatment of textile wastewaters and effluents containing electron-withdrawing pollutants, such as nitro-aromatic and polychlorinated compounds.

APA, Harvard, Vancouver, ISO, and other styles

4

ELENA, PERDUM, MEDVEDOVICI ANDREI VALENTIN, TACHE FLORENTIN, VISILEANU EMILIA, DUMITRESCU IULIANA, MITRAN CORNELIA-ELENA, IORDACHE OVIDIU-GEORGE, and RADULESCU ION RAZVAN. "Some validation aspects on the analytical method for assaying carcinogenic amines from textile dyes." Industria Textila 69, no. 03 (July 1, 2018): 249–56. http://dx.doi.org/10.35530/it.069.03.1521.

Full text

Abstract:

Chemicals safety control and ecological properties have become a priority for the textile industry in order to avoid the negative effects on humans and environment. The increasing interest for toxicology of textiles is determined by the presence of dangerous compounds in clothes generated from dyeing and finishing processes. In order to protect human health, European Regulations as Oeko Tex Standard 100 and REACH Regulation limit the presence of dangerous chemicals, such as aromatic amines, generated by reductive cleavage of azo dyes, by no more than 30 mg/kg of textile material. The main goal of this research work was to develop and validate a HPLC/MWD method for precise and reliable identification and quantification of carcinogenic aromatic amines derived from banned azo dye specific to the textile industry. The simultaneous determination of 24 regulated aromatic amines has been conducted by two chromatographic methods according to SR EN ISO 14362-1:2017 in order to avoid matrix interferences and compounds misidentification due to the presence of structural isomers. Preliminary analyses to establish the maximum absorption wavelength of each standard solution of aromatic amine were performed simultaneously at four wavelengths, 240, 280, 305 and 380 nm. With the scope of demonstrating the consistency, reliability and accuracy of the analysed data, both liquid and gas chromatographic method were validated. Parameters as selectivity, precision, limit of detection and limit of quantification of the analytical methods were evaluated. The certainty of the determinations was also proved by the results of proficiency testing conducted by IIS Netherlands on azo dyes in textiles.

APA, Harvard, Vancouver, ISO, and other styles

5

Setiyanto, Henry. "STUDY ON THE FENTON REACTION FOR DEGRADATION OF REMAZOL RED B IN TEXTILE WASTE INDUSTRY." Molekul 11, no. 2 (November 28, 2016): 168. http://dx.doi.org/10.20884/1.jm.2016.11.2.212.

Full text

Abstract:

Remazol Red B is a reactive dye that is often used in the textile industry. The dye can cause serious problems in the environmental / water because it is difficult to be degraded by microorganisms. Decolorization of reactive azo dyes (Remazol Red B) before being discharged into the environment is an important aspect in creating technology (method) that are environmentally friendly. The method chosen for this decolorization is Advanced Oxidation Process (AOP) using the Fenton reaction. The optimum conditions for this reaction is 25 mg/L H2O2 and 1.25 mg/L of Fe2+ to Remazol Red B with initial concentration at 83 mg/L ( with ratio [H2O2]/[Fe2+] = 20). The optimum conditions of this reaction were obtained at pH 3 and temperature of 27 0C, with decolorization efficiency up to 100% for a reaction time of 60 minutes. The kinetic model of dye decoloritation follow the second order reaction. Some of the metal ions were added i.e. Cu2+, Pb2+ and Zn2+ , given no significant impact on the degradation performed.

APA, Harvard, Vancouver, ISO, and other styles

6

Khaligh, Nader Ghaffari, Mohd Rafie Johan, and Juan Joon Ching. "Saccharin: a cheap and mild acidic agent for the synthesis of azo dyes via telescoped dediazotization." Green Processing and Synthesis 8, no. 1 (January 28, 2019): 24–29. http://dx.doi.org/10.1515/gps-2017-0133.

Full text

Abstract:

Abstract Green synthesis methods are considered as a safer alternative to the conventional synthetic processes due to their eco-friendly nature, cost-effectiveness, and easy handling. In the present study, an eco-friendly and sustainable method for the synthesis of stable arenediazonium has been developed using saccharin as a cheap and mild acidic agent and tert-butyl nitrite as a diazotization reagent for the first time. These stable intermediates were used in the azo coupling reaction with 4-hydroxybenzaldehyde via telescoped dediazotization. The current method has advantages such as reduced waste by avoiding solvent for the purification of intermediate in diazotization step, cost-effectiveness, simple experimental procedure, good yield of azo dyes, metal-free waste, and environmentally benign conditions. An interesting aspect of this study is the recovery of saccharin from the reaction, which could be reused.

APA, Harvard, Vancouver, ISO, and other styles

7

Mohan, S. Venkata, S. V. Ramanaiah, and P. N. Sarma. "Biosorption of direct azo dye from aqueous phase onto Spirogyra sp. I02: Evaluation of kinetics and mechanistic aspects." Biochemical Engineering Journal 38, no. 1 (January 2008): 61–69. http://dx.doi.org/10.1016/j.bej.2007.06.014.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Basu, Anirban, and Gopinatha Suresh Kumar. "Interaction of toxic azo dyes with heme protein: Biophysical insights into the binding aspect of the food additive amaranth with human hemoglobin." Journal of Hazardous Materials 289 (May 2015): 204–9. http://dx.doi.org/10.1016/j.jhazmat.2015.02.044.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Liakou, S., S. Pavlou, and G. Lyberatos. "Ozonation of azo dyes." Water Science and Technology 35, no. 4 (February 1, 1997): 279–86. http://dx.doi.org/10.2166/wst.1997.0137.

Full text

Abstract:

Ozone pretreatment studies of wastewater containing a specific azo dye – Orange II - were conducted in order to assess the kinetics of ozone oxidation and to evaluate the effect of ozonation on the biodegradability of the wastewater. Batch experiments were performed at different initial concentrations of the dye, showing that ozone is capable of a rapid disruption of the dye molecule. Moreover, the production of biodegradable compounds is apparent from the evolution of COD and BOD5 measurements. A mathematical model which describes the dye elimination, the COD and BOD5 variation, and the amount of ozone reacted has been developed.

APA, Harvard, Vancouver, ISO, and other styles

10

Lauth, G., W. Hoelderich, and G. Wagenblast. "Molecular sieves containing azo dyes." Zeolites 15, no. 2 (February 1995): 184. http://dx.doi.org/10.1016/0144-2449(95)90103-5.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Mon, Wai Phyo, Phongphan Jantaharn, Sophon Boonlue, Sirirath McCloskey, Somdej Kanokmedhakul, and Wiyada Mongkolthanaruk. "Enzymatic Degradation of Azo Bonds and Other Functional Groups on Commercial Silk Dyes by Streptomyces coelicoflavus CS-29." Environment and Natural Resources Journal 20, no. 1 (September 21, 2021): 1–10. http://dx.doi.org/10.32526/ennrj/20/202100104.

Full text

Abstract:

Azo dyes are used for silk textile manufacture, where their decolorization and detoxication are necessary after initial dying in the craft industry. The bio-decolorization efficiency of Streptomyces coelicoflavus CS-29 toward commercial azo blue and red dyes was investigated, analyzing the degradation and adsorption of dye molecules. S. coelicoflavus CS-29 showed reductions of 70% and 51% in red and blue dyes, respectively, after seven days. Morphological observation by light microscopy showed that dye molecules were adsorbed onto S. coelicoflavus CS-29 cell surface to form a dense cell pellet. Moreover, peroxidase and laccase activity were detected as extracellular enzymes, but no azo-reductase was detected. From the enzymatic activity, changes of dye profiles in HPLC showed differences between control dyes (untreated dyes) and metabolized products of dyes treated with S. coelicoflavus CS-29. The presence of main functional azo groups (-N=N-) in both blue and red silk dyes was indicated by FTIR analysis, in the untreated azo dyes. The azo bonds seemed to disappear in metabolites after S. coelicoflavus CS-29 treatment and other functional groups were changed compared to the control dyes. The treated dyes showed no significant effect on seed germination, root length, and shoot length of mung beans during phytotoxicity analysis. The red dyes showed a more negative effect on shoot lengths than the blue dyes. The overall results showed that S. coelicoflavus CS-29 is an effective and promising tool for the treatment of dye contaminated wastewater and the permanent elimination of recalcitrant commercial azo dye pollutants.

APA, Harvard, Vancouver, ISO, and other styles

12

Jadhav, Indrani, Roshan Vasniwal, Divya Shrivastav, and Kapilesh Jadhav. "Microorganism-Based Treatment of Azo Dyes." Journal of Environmental Science and Technology 9, no. 2 (February 15, 2016): 188–97. http://dx.doi.org/10.3923/jest.2016.188.197.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Liu, Guangfei, Jing Wang, Hong Lu, Ruofei Jin, Jiti Zhou, and Long Zhang. "Effects of reduction products of ortho-hydroxyl substituted azo dyes on biodecolorization of azo dyes." Journal of Hazardous Materials 171, no. 1-3 (November 2009): 222–29. http://dx.doi.org/10.1016/j.jhazmat.2009.05.136.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Ngo, Anna Christina R., and Dirk Tischler. "Microbial Degradation of Azo Dyes: Approaches and Prospects for a Hazard-Free Conversion by Microorganisms." International Journal of Environmental Research and Public Health 19, no. 8 (April 14, 2022): 4740. http://dx.doi.org/10.3390/ijerph19084740.

Full text

Abstract:

Azo dyes have become a staple in various industries, as colors play an important role in consumer choices. However, these dyes pose various health and environmental risks. Although different wastewater treatments are available, the search for more eco-friendly options persists. Bioremediation utilizing microorganisms has been of great interest to researchers and industries, as the transition toward greener solutions has become more in demand through the years. This review tackles the health and environmental repercussions of azo dyes and its metabolites, available biological approaches to eliminate such dyes from the environment with a focus on the use of different microorganisms, enzymes that are involved in the degradation of azo dyes, and recent trends that could be applied for the treatment of azo dyes.

APA, Harvard, Vancouver, ISO, and other styles

15

Chung, King-Thom, and S. Edward Stevens. "Degradation azo dyes by environmental microorganisms and helminths." Environmental Toxicology and Chemistry 12, no. 11 (November 1993): 2121–32. http://dx.doi.org/10.1002/etc.5620121120.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Liakou, S., M. Kornaros, and G. Lyberatos. "Pretreatment of azo dyes using ozone." Water Science and Technology 36, no. 2-3 (July 1, 1997): 155–63. http://dx.doi.org/10.2166/wst.1997.0508.

Full text

Abstract:

Wastewaters produced in textile industrial processes contain organic dyes which are not easily amenable to biological treatment. Pretreatment with ozone is a promising method for oxidation of those dyes to more degradable compounds. The aim of this work is to assess the oxidation kinetics of a specific azo dye used in the textile industry, Orange II. Batch experiments were conducted in order to elucidate the oxidation route of the dye. Oxalate, formate and benzenesulfonate are found to be the oxidation intermediate compounds. A mathematical model which describes the dye elimination, the COD and BOD5 variation, the amount of ozone reacted and the time evolution of the intermediate compounds has been developed.

APA, Harvard, Vancouver, ISO, and other styles

17

Hustert, Klaus, and Richard G. Zepp. "Photocatalytic degradation of selected azo dyes." Chemosphere 24, no. 3 (February 1992): 335–42. http://dx.doi.org/10.1016/0045-6535(92)90301-7.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Bafana, Amit, Sivanesan Saravana Devi, and Tapan Chakrabarti. "Azo dyes: past, present and the future." Environmental Reviews 19, NA (December 2011): 350–71. http://dx.doi.org/10.1139/a11-018.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Razo-Flores, Elías, Maurice Luijten, Brian Donlon, Gatze Lettinga, and Jim Field. "Biodegradation of selected azo dyes under methanogenic conditions." Water Science and Technology 36, no. 6-7 (September 1, 1997): 65–72. http://dx.doi.org/10.2166/wst.1997.0576.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

20

Stolz, A. "Basic and applied aspects in the microbial degradation of azo dyes." Applied Microbiology and Biotechnology 56, no. 1-2 (July 1, 2001): 69–80. http://dx.doi.org/10.1007/s002530100686.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Jiang, H., and P. L. Bishop. "Aerobic biodegradation of azo dyes in biofilms." Water Science and Technology 29, no. 10-11 (October 1, 1994): 525–30. http://dx.doi.org/10.2166/wst.1994.0800.

Full text

Abstract:

Factors affecting biofilm removal of azo dyes from a synthetic, municipal-type wastewater were investigated using lab-scale, rotating drum biofilm reactors. Among the three azo dyes studied - Acid Orange 8, Acid Orange 10, and Acid Red 14 - only AO-8 degraded aerobically. The azo bond cleavage occurred very easily for all three dyes under anaerobic conditions. AO-8 removals ranged from 20% to 90%. Statistically designed experiments were used to characterize the response of pseudo-steady state biofilms. Two AO-8 removal rate maxima were identified - one at high bulk-phase dissolved oxygen and low COD removal flux, and the other at low dissolved oxygen and high COD flux. The presence of azo dyes, along with other factors such as COD loading, bulk-phase DO level and shear force, showed impact on biofilm accumulation.

APA, Harvard, Vancouver, ISO, and other styles

22

Hu, T. L. "Kinetics of azoreductase and assessment of toxicity of metabolic products from azo dyes by Pseudomonas luteola." Water Science and Technology 43, no. 2 (January 1, 2001): 261–69. http://dx.doi.org/10.2166/wst.2001.0098.

Full text

Abstract:

This is a continuous study on a decolorization strain, Pseudomonas luteola, which involves treating seven azo dyes with different structures. This study focuses mainly on determining both the mechanism of decolorization by P. luteola and the activity of azoreductase from P. luteola as well as identifying and assessing the toxicity of metabolic products of azo dyes. The growth of P. luteola reached the stationary phase after shaking incubation for 24 hours. Then, while being kept static, the color of seven tested azo dyes (100 mg/l) could be removed. The proportion of color removal was between 59–99%, which figure is related to the structure of the dye. Monoazo dyes (RP2B, V2RP and Red 22) showed the fastest rate of decolorization, i.e. from 0.23–0.44 mg dye-mg cell–1 hr–1. P. luteola could remove the color of V2RP and a leather dye at a concentration of 200 mg/l, and as to the rest of the azo dyes, it could remove at a concentration of up to 100 mg/l. Decolorization of RP2B and Red 22 required activation energy of 7.00 J/mol and 6.63 J/mole, respectively, indicating that it was easier for azoreductase to decolorize structurally simple dyes. The kinetics of azoreductase towards seven azo dyes suggested a competitive inhibition model be applied. Microtox® was used to analyze the toxicity of the metabolic products of azo dyes. EC50 showed differences in toxicity before and after the azo dyes had been metabolized. Analysis revealed significant differences between the results obtained by EC50 with Blue 15 and those obtained with the leather dye, indicating that the toxicities of the metabolic products were increased. The differences obtained by EC50 with Red 22, RP2P and V2RP were small, and Black 22 showed no such difference. Sulfanic acid and orthanilic acid may be the intermediate products of Violet 9 and RP2B, respectively. However, according to FT-IR analysis, aromatic amines were present in the metabolic product.

APA, Harvard, Vancouver, ISO, and other styles

23

Coughlin, M. F., B. K. Kinkle, A. Tepper, and P. L. Bishop. "Characterization of aerobic azo dye-degrading bacteria and their activity in biofilms." Water Science and Technology 36, no. 1 (July 1, 1997): 215–20. http://dx.doi.org/10.2166/wst.1997.0051.

Full text

Abstract:

An azo dye-degrading strain, originally named TBX65, was isolated from the mixed liquor of the Mill Creek waste water treatment plant in Cincinnati, Ohio. Strain TBX65 has the unusual ability to aerobically reduce the azo bond of several azo dyes and is able to use some of these dyes as growth substrate. Subsequent investigations have revealed that TBX65 is actually composed of several strains including two azo dye-degrading strains, MC1 and MI2. Strain MI2 is able to use the azo dyes AO7 and AO8 as its sole source of carbon, energy, and nitrogen. In contrast, MC1 can aerobically reduce the azo bond of these dyes but only in the presence of an exogenous source of carbon and nitrogen. Both MC1 and MI2 are Gram negative, rod-shaped bacteria that form yellow colonies. Sequencing and phylogenetic analysis of the 16S rRNA gene of MC1 indicates that it is a strain of Sphingomonas. Based on this phylogenetic analysis, the most closely related strain to MC1 is strain C7, a previously described azo dye-degrading bacterium isolated from biofilms growing in our laboratories. A strain-specific fluorescent antibody has been developed for strains MC1 and MI2, and is being used to determine the survival and azo dye-degrading ability of these strains in biofilms generated in a rotating drum bioreactor.

APA, Harvard, Vancouver, ISO, and other styles

24

Rodríguez, A., J. García, G. Ovejero, and M. Mestanza. "Wet air and catalytic wet air oxidation of several azodyes from wastewaters: the beneficial role of catalysis." Water Science and Technology 60, no. 8 (October 1, 2009): 1989–99. http://dx.doi.org/10.2166/wst.2009.526.

Full text

Abstract:

Degradation of several azo dyes, Acid Orange 7 (AO7), Acid Orange 74 (AO74), Direct Blue 71 (DB71), Reactive Black 5 (RB5) and Eriochrome Blue Black B (EBBB), well-known non-biodegradable mono, di and tri azo dyes has been studied using, wet-air oxidation (WAO) and catalytic wet air oxidation (CWAO). The efficiency of substrate decolorization and mineralization in each process has been comparatively discussed by evolution concentration, chemical oxygen demand, total organic carbon content and toxicity of dyes solutions. The most efficient method on decolorization and mineralization (TOC) was observed to be CWAO process. Mineralization efficiency with wet air and catalytic wet air oxidation essays was observed in the order of mono-azo > di-azo > tri-azo dye. Final solutions of CWAO applications after 180 min treatment can be disposed safely to environment.

APA, Harvard, Vancouver, ISO, and other styles

25

Wang, Cuiping, Yanwei Zhang, Li Yu, Zhiyuan Zhang, and Hongwen Sun. "Oxidative degradation of azo dyes using tourmaline." Journal of Hazardous Materials 260 (September 2013): 851–59. http://dx.doi.org/10.1016/j.jhazmat.2013.06.054.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Li, Haijun, Chong Tang, Min Wang, Changgen Mei, and Na Liu. "Decolorization of azo dyes in a heterogeneous persulfate system using FeS as the activator." Water Science and Technology 83, no. 7 (February 24, 2021): 1703–13. http://dx.doi.org/10.2166/wst.2021.085.

Full text

Abstract:

Abstract Textile effluents containing synthetic refractory azo dyes are one of the most important sources of water pollution. However, these kinds of refractory organic pollutants did not resist a persulfate (PS) oxidation process which was correctly activated. In this study, PS was activated by ferrous sulfide (FeS) in a heterogeneous system to break down azo dyes wastewater. The results showed that all five selected azo dyes were efficiently broken down using the PS/FeS system, except for DY 12, and more than 95% of azo dyes were decolored within 60 minutes. The decolorization efficiency of DR 81 in the PS/FeS system was comparable to PS activated with heat (60 °C) or Fe2+, and was slightly superior to Fe0 powders under the same conditions. Quenching studies indicated that both SO4−• and •OH were formed in the FeS surface and diffused into the solution to facilitate the successive transformation of DR 81, the •OH reaction with DR 81 might the crucial reaction. The coexisting chelating agents in real azo dye effluents at high concentrations had a negative influence on azo dye decolorization by PS/FeS. However, the superior factor of the PS/FeS system was the regenerability and reusability of the heterogeneous catalyst.

APA, Harvard, Vancouver, ISO, and other styles

27

Chung, King-Thom, and S. Edward Stevens. "DEGRADATION OF AZO DYES BY ENVIRONMENTAL MICROORGANISMS AND HELMINTHS." Environmental Toxicology and Chemistry 12, no. 11 (1993): 2121. http://dx.doi.org/10.1897/1552-8618(1993)12[2121:doadbe]2.0.co;2.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Kalyuzhnyi, S., N. Yemashova, and V. Fedorovich. "Kinetics of anaerobic biodecolourisation of azo dyes." Water Science and Technology 54, no. 2 (July 1, 2006): 73–79. http://dx.doi.org/10.2166/wst.2006.488.

Full text

Abstract:

Kinetics of anaerobic biodecolourisation (methanogenic environment) of four azo dyes (Acid Orange 6, Acid Orange 7, Methyl Orange and Methyl Red) was investigated with regard to their electrochemical properties as well as under variation of dye and sludge concentrations, pH and temperature. Cyclic voltammetry revealed a correlation between the potential of irreversible reduction peak of the dye and its first-order decolorisation constant. For each dye tested, this decolourisation constant was adversely proportional to dye concentration (0.086–1.7 mM) and had a saturation (hyperbolic) dependency on sludge concentration (0.04–1.1 g VSS/l), a bell-shape dependency on pH (4.0–9.0) and Arrhenius dependency on temperature (24–40 °C). Transfer from methanogenic to sulphate reducing environment led to an increase of decolorisation constant for all the dyes investigated due to the abundant presence of sulphide as a reducing agent in the reaction medium. Similar transfer to a denitrifying environment resulted in an almost complete decease of decolourisation because nitrate easily outcompetes azo dyes as an electron acceptor.

APA, Harvard, Vancouver, ISO, and other styles

29

Rahi, Ravi Kant, and Varsha Gupta. "Biodegradation of Carcinogenic Reactive Azo Dyes by Indigenous Bacterial Consortium X5RC5." Journal of Environmental Science and Management 24, no. 2 (December 31, 2021): 54–61. http://dx.doi.org/10.47125/jesam/2021_2/06.

Full text

Abstract:

Reactive azo dyes are considered as a major source of water and soil contamination. Carcinogenicity and the recalcitrant nature of these dyes is a worldwide problem. Exclusion of these dyes from the effluent is necessary for a clean and green environment. A bacterial consortium X5RC5 was developed for the effective removal of two of the primary reactive azo dyes utilized widely in textile industries (reactive orange 3R and reactive red HE7B). The consortium includes two indigenous bacterial isolates, Lysinibacillus macroides and Stenotrophomonas acidaminiphila, from textile effluent. The X5RC5 completely degraded the reactive orange 3R in 4 days and reactive red HE7B in 5 days of incubation periods. In two days, more than 50% degradation was observed for both dyes. Biodegradation of these dyes was affirmed through the UV-Vis spectra and Fourier-transform infrared spectroscopy (FTIR) analysis. This investigation advances the utilization of consortium X5RC5 as a biological tool for the bio-handling of effluent containing dyes.

APA, Harvard, Vancouver, ISO, and other styles

30

Demirev, Anton, and Valentin Nenov. "Ozonation of Two Acidic Azo Dyes with Different Substituents." Ozone: Science & Engineering 27, no. 6 (December 2005): 475–85. http://dx.doi.org/10.1080/01919510500351834.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Joudi, Meryeme, Jihan Mouldar, Houyem Hafdi, Hamid Nasrellah, Badreddine Hatimi, Moulay Abderrahim El Mhammedi, and Mina Bakasse. "Factorial experimental design for the removal of disperse dyes using hydroxyapatite prepared from Moroccan phosphogypsum." Mediterranean Journal of Chemistry 8, no. 1 (February 2, 2019): 1–9. http://dx.doi.org/10.13171/mjc811902219mb.

Full text

Abstract:

Azo dyes are the major group of synthetic dyes known and have given rise to many water and soil environmental problems, the most of this azo dyes were used in textile industry. The aim of this study is the removal of Disperse Blue 79 (DB 79) and Disperse Blue 165 (DB 165) as azo dyes by Hydroxyapatite (HAP). The adsorption experiments were carried out to investigate the factors that influence the dyes uptake by hydroxyapatite, such as the contact time under agitation, adsorbent dosage, initial dye concentration and size of HAP. To reduce the number of experiments, full factorial experimental design at two levels (24) was used to achieve optimal conditions for the removal of DB 79 and DB 165 from aqueous solutions.

APA, Harvard, Vancouver, ISO, and other styles

32

Cervantes, F. J., A. B. dos Santos, M. P. de Madrid, A. J. M. Stams, and J. B. van Lier. "Reductive decolourisation of azo dyes by mesophilic and thermophilic methanogenic consortia." Water Science and Technology 52, no. 1-2 (July 1, 2005): 351–56. http://dx.doi.org/10.2166/wst.2005.0538.

Full text

Abstract:

The contribution of acidogenic bacteria and methanogenic archaea on the reductive decolourisation of azo dyes was assessed in anaerobic granular sludge. Acidogenic bacteria appeared to play an important role in the decolourising processes when glucose was provided as an electron donor; whereas methanogenic archaea showed a minor role when this substrate was supplemented in excess. In the presence of the methanogenic substrates acetate, methanol, hydrogen and formate, methane production became important only after colour was totally removed from the batch assays. This retardation in methane production may be due to either a toxic effect imposed by the azo dyes or to the competitive behaviour of azo dyes to the methanogenic consortia for the available reducing equivalents.

APA, Harvard, Vancouver, ISO, and other styles

33

Pinheiro, Lucas Rafael Santana, Diana Gomes Gradíssimo, Luciana Pereira Xavier, and Agenor Valadares Santos. "Degradation of Azo Dyes: Bacterial Potential for Bioremediation." Sustainability 14, no. 3 (January 28, 2022): 1510. http://dx.doi.org/10.3390/su14031510.

Full text

Abstract:

The use of dyes dates to ancient times and has increased due to population and industrial growth, leading to the rise of synthetic dyes. These pollutants are of great environmental impact and azo dyes deserve special attention due their widespread use and challenging degradation. Among the biological solutions developed to mitigate this issue, bacteria are highlighted for being versatile organisms, which can be applied as single organism cultures, microbial consortia, in bioreactors, acting in the detoxification of azo dyes breakage by-products and have the potential to combine biodegradation with the production of products of economic interest. These characteristics go hand in hand with the ability of various strains to act under various chemical and physical parameters, such as a wide range of pH, salinity, and temperature, with good performance under industry, and environmental, relevant conditions. This review encompasses studies with promising results related to the use of bacteria in the bioremediation of environments contaminated with azo dyes in the most diverse techniques and parameters, both in environmental and laboratory samples, also addressing their mechanisms and the legislation involving these dyes around the world, showcasing the importance of bacterial bioremediation, specialty in a scenario in an ever-increasing pursuit for sustainable production.

APA, Harvard, Vancouver, ISO, and other styles

34

Gudelj, Ivana, Jasna Hrenović, Tibela Dragičević, Frane Delaš, Vice Šoljan, and Hrvoje Gudelj. "Azo Dyes, Their Environmental Effects, and Defining a Strategy for Their Biodegradation and Detoxification." Archives of Industrial Hygiene and Toxicology 62, no. 1 (March 1, 2011): 91–101. http://dx.doi.org/10.2478/10004-1254-62-2011-2063.

Full text

Abstract:

Azo Boje, Njihov Utjecaj Na Okoliš I Potencijal Biotehnološke Strategije Za Njihovu Biorazgradnju I DetoksifikacijuIntenzivan industrijski razvoj popraćen je sve većom kompleksnošću sastava otpadnih voda, što u smislu učinkovite zaštite okoliša i održivog razvoja nalaže potrebu pospješivanja kvalitete postojećih te uvođenjem novih postupaka obrade otpadnih voda, kao iznimno važnog čimbenika u interakciji čovjeka i okoliša. Posebnu znanstveno-tehnološku pozornost zahtijevaju novosintetizirani ksenobiotici, poput azo-boja, koji su u prirodi veoma teško razgradivi. Azo-boje podložne su bioakumulaciji, a zbog alergijskih, kancerogenih, mutagenih i teratogenih svojstava nerijetko su prijetnja zdravlju ljudi i očuvanju okoliša. Primjenu fizikalnokemijskih metoda za uklanjanje azo-boja iz otpadnih voda često ograničavaju visoke cijene, potrebe za odlaganjem nastalog štetnog mulja ili nastanak toksičnih sastojaka razgradnje. Biotehnološki postupci su, zbog mogućnosti ekonomične provedbe i postizanja potpune biorazgradnje, a time i detoksifikacije, sve zastupljeniji u obradi svih vrsta otpadnih voda, pa tako i onih koje sadržavaju azo-boje.

APA, Harvard, Vancouver, ISO, and other styles

35

Zissi, U., and G. Lyberatos. "Axo-dye biodegradation under anoxic conditions." Water Science and Technology 34, no. 5-6 (September 1, 1996): 495–500. http://dx.doi.org/10.2166/wst.1996.0588.

Full text

Abstract:

Biological oxidation of azo-dyes is important for wastewater treatment. Azo-dyes are synthetic organic colorants that exhibit great structural variety. A large majority of these dyes are released into the environment. The textile industry and dyestuff manufacturing industry are two major sources of released azodyes. In the present study, we focus on the anoxic degradation of a disperse azo-dye, p-aminoazobenzene (pAAB), a simple azo-dye, by a pure culture of Bacillus subtilis, growing on a synthetic medium. Bacillus subtilis is a bacterium capable of using nitrate and/or nitrite as terminal electron acceptor under anoxic conditions. This bacterium lacks the capability for fermentation. The degradation of p-aminoazobenzene by Bacillus subtilis was examined through batch experiments in order to elucidate the mechanism of dye degradation. The results proved that Bacillus subtilis co-metabolizes p-aminoazobenzene under denitrifying conditions, in the presence of glucose as carbon source, producing aniline and p-phenylenediamine as the nitrogen-nitrogen double bond is broken.

APA, Harvard, Vancouver, ISO, and other styles

36

Guo, Guang, Fang Tian, Can Zhang, Tingfeng Liu, Feng Yang, Zhixin Hu, Chong Liu, Shiwei Wang, and Keqiang Ding. "Performance of a newly enriched bacterial consortium for degrading and detoxifying azo dyes." Water Science and Technology 79, no. 11 (June 1, 2019): 2036–45. http://dx.doi.org/10.2166/wst.2019.210.

Full text

Abstract:

Abstract To obtain a bacterial consortium that can degrade azo dyes effectively, a bacterial consortium was enriched that can degrade Metanil yellow effectively. After 6 h, 96.25% Metanil yellow was degraded under static conditions by the bacterial consortium, which was mainly composed of Pseudomonas, Lysinibacillus, Lactococcus, and Dysgonomonas. In particular, Pseudomonas played a main role in the decolorization process. Co-substrate increased the decolorization rate, and yeast powder, peptone, and urea demonstrated excellent effects. The optimal pH value and salinity for the decolorization of azo dyes is 4–7 and 1% salinity respectively. The bacterial consortium can directly degrade many azo dyes, such as direct fast black G and acid brilliant scarlet GR. Azo reductase activity, laccase activity, and lignin peroxidase activity were estimated as the key reductase for decolorization, and Metanil yellow can be degraded into less toxic degradation products through synergistic effects. The degradation pathway of Metanil yellow was analyzed by Fourier transform infrared spectroscopy and gas chromatography–mass spectrometry, which demonstrated that Metanil yellow was cleaved at the azo bond, producing p-aminodiphenylamine and diphenylamine. These findings improved our knowledge of azo-dye-decolorizing microbial resources and provided efficient candidates for the treatment of dye-polluted wastewaters.

APA, Harvard, Vancouver, ISO, and other styles

37

Corso, C. R., E. J. R. Almeida, G. C. Santos, L. G. Morão, G. S. L. Fabris, and E. K. Mitter. "Bioremediation of direct dyes in simulated textile effluents by a paramorphogenic form of Aspergillus oryzae." Water Science and Technology 65, no. 8 (April 1, 2012): 1490–95. http://dx.doi.org/10.2166/wst.2012.037.

Full text

Abstract:

Azo dyes are extensively used for coloring textiles, paper, food, leather, drinks, pharmaceutical products, cosmetics and inks. The textile industry consumes the largest amount of azo dyes, and it is estimated that approximately 10–15% of dyes used for coloring textiles may be lost in waste streams. Almost all azo dyes are synthetic and resist biodegradation, however, they can readily be reduced by a number of chemical and biological reducing systems. Biological treatment has advantages over physical and chemical methods due to lower costs and minimal environmental effect. This research focuses on the utilization of Aspergillus oryzae to remove some types of azo dyes from aqueous solutions. The fungus, physically induced in its paramorphogenic form (called ‘pellets’), was used in the dye biosorption studies with both non-autoclaved and autoclaved hyphae, at different pH values. The goals were the removal of dyes by biosorption and the decrease of their toxicity. The dyes used were Direct Red 23 and Direct Violet 51. Their spectral stability (325–700 nm) was analyzed at different pH values (2.50, 4.50 and 6.50). The best biosorptive pH value and the toxicity limit, (which is given by the lethal concentration (LC100), were then determined. Each dye showed the same spectrum at different pH values. The best biosorptive pH was 2.50, for both non- autoclaved and autoclaved hyphae of A. oryzae. The toxicity level of the dyes was determined using the Trimmed Spearman–Karber Method, with Daphnia similis in all bioassays. The Direct Violet 51 (LC100 400 mg · mL−1) was found to be the most toxic dye, followed by the Direct Red 23 (LC100 900 mg · mL−1). The toxicity bioassays for each dye have shown that it is possible to decrease the toxicity level to zero by adding a small quantity of biomass from A. oryzae in its paramorphogenic form. The autoclaved biomass had a higher biosorptive capacity for the dye than the non-autoclaved biomass. The results show that bioremediation occurs with A. oryzae in its paramorphogenic form, and it can be used as a biosorptive substrate for treatment of industrial waste water containing azo dyes.

APA, Harvard, Vancouver, ISO, and other styles

38

Quezada, M., I. Linares, and G. Buitrón. "Use of a sequencing batch biofilter for degradation of azo dyes (acids and bases)." Water Science and Technology 42, no. 5-6 (September 1, 2000): 329–36. http://dx.doi.org/10.2166/wst.2000.0532.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

39

Rawat, Deepak, Vandana Mishra, and Radhey Shyam Sharma. "Detoxification of azo dyes in the context of environmental processes." Chemosphere 155 (July 2016): 591–605. http://dx.doi.org/10.1016/j.chemosphere.2016.04.068.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Prato-Garcia, D., and G. Buitrón. "Solar photoassisted advanced oxidation process of azo dyes." Water Science and Technology 59, no. 5 (March 1, 2009): 965–72. http://dx.doi.org/10.2166/wst.2009.071.

Full text

Abstract:

Advanced oxidation processes assisted with natural solar radiation in CPC type reactors (parabolic collector compound), was applied for the degradation of three azo dyes: acid orange (AO7), acid red 151 (AR151) and acid blue 113 (AB113). Fenton, Fenton like and ferrioxalate-type complexes showed to be effective for degrade the azo linkage and moieties in different extensions. Initially, the best dose of reagents (Fe3 + -H2O2) was determined through a factorial experimental design, next, using response surface methodologies, the reagent consumption was reduced up to 40%, maintaining in all cases high decolourisation percentages (>98%) after 60 min. of phototreatment. In this work, it was also studied the effect of concentration changes of the influent between 100–300 mg/L and the operation of the photocatalytic process near neutral conditions (pH 6.0–6.5) by using ferrioxalate type complex (FeOx).

APA, Harvard, Vancouver, ISO, and other styles

41

Nam, Sangkil, and V. Renganathan. "Non-enzymatic reduction of azo dyes by NADH." Chemosphere 40, no. 4 (February 2000): 351–57. http://dx.doi.org/10.1016/s0045-6535(99)00226-x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Michaels, Glenda B., and David L. Lewis. "Microbial transformation rates of AZO and triphenylmethane dyes." Environmental Toxicology and Chemistry 5, no. 2 (February 1986): 161–66. http://dx.doi.org/10.1002/etc.5620050206.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Taheri, Mahsa. "Techno-economical aspects of electrocoagulation optimization in three acid azo dyes’ removal comparison." Cleaner Chemical Engineering 2 (June 2022): 100007. http://dx.doi.org/10.1016/j.clce.2022.100007.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Wang, Yifeng, Dan Zhao, Wanhong Ma, Chuncheng Chen, and Jincai Zhao. "Enhanced Sonocatalytic Degradation of Azo Dyes by Au/TiO2." Environmental Science & Technology 42, no. 16 (August 2008): 6173–78. http://dx.doi.org/10.1021/es800168k.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Zhang, Guoyang, and Shujuan Zhang. "Quantitative structure-activity relationship in the photodegradation of azo dyes." Journal of Environmental Sciences 90 (April 2020): 41–50. http://dx.doi.org/10.1016/j.jes.2019.11.009.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Edwards, Laura C., and Harold S. Freeman. "Synthetic dyes based on environmental considerations. Part 3: Aquatic toxicity of iron-complexed azo dyes." Coloration Technology 121, no. 5 (September 2005): 265–70. http://dx.doi.org/10.1111/j.1478-4408.2005.tb00284.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

47

Kalyuzhnyi, S., and V. Sklyar. "Biomineralisation of azo dyes and their breakdown products in anaerobic-aerobic hybrid and UASB reactors." Water Science and Technology 41, no. 12 (June 1, 2000): 23–30. http://dx.doi.org/10.2166/wst.2000.0233.

Full text

Abstract:

Batch toxicity and biodegradability of two azo dyes (Siriusgelb and Siriuslichtbraun) has been investigated. It was found that the former azo dye was significantly less toxic to methanogenic sludge than the latter one (IC50 are equal to 3.55 and 0.41 g COD/l, respectively). Neither of the azo dyes was biodegradable under aerobic conditions but both dyes were readily decolourised and slowly mineralised in anaerobic environments. In order to optimise the treatment strategy, the anaerobic and aerobic phases were combined into one single unit called the anaerobic-aerobic hybrid reactor. The performance of this innovative reactor was tested with a synthetic wastewater containing Siriusgelb and ethanol at 30°C and 56% removal of azo dye COD was achieved at volumetric load of 0.3 g azo dye COD/l/day. The effluent COD content could be attributed to the presence of non-biodegradable autooxidation products of Siriusgelb breakdown intermediates. A continuous biomineralisation of 2-aminobenzoic acid (2-ABA) – intermediate of the anaerobic decomposition of Siriuslichtbraun – was studied in a UASB reactor at 30°C. A high (>90%) removal of 2-ABA was achieved under volumetric loads of 1.5 g 2-ABA COD/l/day. However, a further increase in volumetric load led to a decrease in 2-ABA removal, probably due to low attachment ability of the bacteria responsible for primary decomposition of 2-ABA.

APA, Harvard, Vancouver, ISO, and other styles

48

Faldu, Priti, Vishal Kothari, Charmy Kothari, Jalpa Rank, Ankit Hinsu, and Ramesh Kothari. "Toxicity Assessment of Biologically Degraded Product of Textile Dye Acid Red G." Defence Life Science Journal 4, no. 4 (October 21, 2019): 236–43. http://dx.doi.org/10.14429/dlsj.4.14972.

Full text

Abstract:

Azo dyes are of environmental concern due to their recalcitrant nature. Several azo dyes and their decolorized and degraded products exert toxic and mutagenic effects on the flora and fauna. The toxic properties of these azo dyes are due to nature and position of the substitution with respect to the aromatic rings and amino nitrogen atoms. Several studies have thus far been emphasized on biodegradation of azo dye pollutants, though role of their biodegraded product is rarely studied. Given a lack of this understanding, we have analyzed the effects of degraded products of a di-azo textile dye Acid Red G by newly isolated bacterial species, Pseudomonas aeruginosa PFK10 and Brevibacillus choshinensis PFK11. The genotoxicity and cytotoxicity of Acid Red G and their degraded products were tested on HeLa cell line and Human lymphocyte cell, respectively. The data of MTT assay has been shown that activity of degraded products of the Acid Red G were comparable to their parent dye. But chromosome aberration assay and sister chromatid exchange assay did not show any significant changes in chromosomes as compared to positive control mitomicine.

APA, Harvard, Vancouver, ISO, and other styles

49

Hassan, Nur Hudawiyah Abu, Nisa Syukrina Mat Natsir, Siti Noramira Ab Rahman, Farah Diana Mohd Daud, Nur Ayuni Jamal, NorFadhilah Ibrahim, and Norhuda Hidayah Nordin. "Development of High Entropy Alloy (HEA) as Catalyst for Azo Dye Degradation in Fenton Process." Journal of Physics: Conference Series 2129, no. 1 (December 1, 2021): 012101. http://dx.doi.org/10.1088/1742-6596/2129/1/012101.

Full text

Abstract:

Abstract Azo dye is widely used in the textile industry since it is cost effective and simple to use. However, it becomes a continuous source of environmental pollution due to its carcinogenicity and toxicity. Various methods had been used to remove the azo dye in solution. One of the famous and repeatedly used is Fenton process. The Fenton’s process is one of the advanced oxidation process where iron catalysed hydrogen peroxide to generate hydroxyl radical. Treating azo dyes in solution requires a catalyst to enhance the process of degradation. Herein, high entropy alloy (HEA) has been proposed as a catalytic material to enhance the performance of Fenton process for azo dye degradation. HEA has been reported as a promising catalyst due to its high surface area. The higher the number of active sites, the higher the rate of azo dye degradation as more active sites are available for adsorption of azo dyes. The results have shown that HEA can be used as a catalyst to fasten the Fenton’s reaction since the degradation time is proven to be shorter in the presence of HEA. The method derived from the result of this study will contribute in treating azo dyes for wastewater management in Fenton process.

APA, Harvard, Vancouver, ISO, and other styles

50

Harrelkas, F., M. N. Pons, O. Zahraa, A. Yaacoubi, and E. K. Lakhal. "Application of a sequential batch reactor system for textile dyes degradation: comparison between azo and phthalocyanine dyes." Water Science and Technology 55, no. 10 (May 1, 2007): 107–14. http://dx.doi.org/10.2166/wst.2007.313.

Full text

Abstract:

Photocatalysis on supported TiO2 was combined with aerobic biological treatment in a sequential batch reactor to compare the degradation of two textile dyes: a blue azo dye (DR KBL CDG) and a green phthalocyanine dye (DR K4GN). Three reactors were run in parallel. SBR1 was used as a reference and was fed with urban wastewater only. SBR2 and SBR3 were fed with the same urban wastewater combined with pretreated (for SBR2) and non-pretreated (for SBR3) dye solution. For an azo dye concentration of 12 mg/L decolouration yields of 78 and 27% were achieved, respectively, in SBR2 and SBR3. For the phthalocyanine dye, the decolouration yields decreased to 24 and 15%, respectively. Concerning COD removal it decreases for both dyes with and without pretreatment, when the dye concentration increases. Although a detrimental effect on biomass could be observed, bacteria were able to cope with the inhibitory effect of the dyes.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Azo dyes – Environmental aspects'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles