Azo Dyes

Fenton Process, a type of Advanced Oxidation Processes is an efficient method for treating textile wastewaters. However, excessive use of hydrogen peroxide and catalyst has made this process economically non-feasible. Besides, industrial grade hydrogen peroxide costs $390-500 per ton. One of the means to overcome this problem is the in-situ production of hydrogen peroxide. In this paper, a detailed review was conducted on the generation methods, degradation potential and optimum operating parameters for in-situ production of hydrogen peroxide/hydroxyl radicals. Additionally the scavenging aspect for hydroxyl radicals was also investigated. From this review, it can be concluded that hydroxyl radical is highly oxidative and non selective in nature and its in-situ production can be performed through application of catalyst, ozonation, photocatalysis, electro and microbial fuel cells. Furthermore, optimization of operating parameters can result in an increase in the yield of hydroxyl radicals/hydrogen peroxide. Sonolysis as an auxiliary tool has potential to induce synergetic effects in combination with Advanced Oxidation Processes to increase in-situ hydrogen peroxide production. However, the problem of the scavenging effect is an aspect that needs to be dealt with, as hydroxyl radicals are prone to deactivation by scavengers. Therefore based on the review, it is concluded that insitu production of hydrogen peroxide/hydroxyl radical for treating textile wastewater is economically viable and practically feasible if careful selection of process is conducted through selective research. (C) 2014 Elsevier Ltd. All rights reserved.

http://www.sciencedirect.com/science/article/pii/S0959652614009408

This paper describes research on natural azo compounds isolated from fungi, plant, bacteria, and invertebrates. More than 120 biologically active diazene containing alkaloids demonstrate confirmed pharmacological activity, including antitumor, antimicrobial, and antibacterial effects. The structures, origin, and biological activities of azo compounds are reviewed. Utilizing the computer program PASS, some structure-activity relationship new activities are also predicted, pointing toward possible new applications of these compounds. This article emphasizes the role of natural azo compounds as an important source of drug prototypes and leads for drug discovery.

This study used a novel integrated technology of ceramic supported carbon membrane (CSCM) to degrade azo dyes through an anaerobic mixed culture. The CSCM worked simultaneously as biofilm support, redox mediator, and nano-filter to enhance the dye decolorization efficiency. The decolorization of Acid Orange 7 (AO7) was initially investigated with and without microorganisms in both ceramic support (CS) and CSCM reactors. The CSCM bioreactor (B-CSCM), operated with microorganisms, gave a maximum decolorization of 98% using a CSCM evolved from 10% weight (wt.) of Matrimid 5218 solution. To know the influence of permeate flow, feed concentration, and dye structure on the decolorization process, different B-CSCMs for dye removal experiments were studied over monoazo AO7, diazo Reactive Black 5 (RB5), and triazo Direct Blue 71 (DB71). The highest color removal, operated with 50 mg·L−1 feed solution and 0.05 L·m−2·h−1 of permeate flux, was 98%, 82%, and 72%, respectively, for AO7, RB5, and...

A biosurfactant producing Gram positive bacterium isolated from anodic biofilm of textile wastewater fed MFC was identified as Bacillus sp. MFC (Accession number: MT322244). Scanning Electron Microscopy of the bacterium showed appendages, the bacterium forms biofilm on Congo red agar medium. The obtained results showed that the addition of 5 mg/l endogenous biosurfactant to the bacterial cells resulted in 19-fold increase in bacterial surface-bound exopolysaccharides (EPS) and 1.94-fold increase in biofilm. However, when the bio-surfactant concentration increased to 20 and 40 mg/l, EPS and biofilm decreased and the cells lost their colony forming ability. The dielectric properties of the bacterial cells showed increase in conductivity and relative permittivity with increasing biosurfactant concentrations. The shape of the voltammogram currents peak, their location and Electrochemical impedance spectroscopy (EIS) suggest the involvement of biofilm as direct electron transfer pathway....

This study focuses on the synthesis of the 2-[2\-(5-bromo thiazolyl) azo]-5-di-methyl
amino benzoic acid (5-BrTAMB) and Cd(II) coordinate complex. Diazotization by 2-amino-5- bromo thiazole and mixation by an alkaline alcohol solution of the 3-dimethyl amino benzoic acid. Various analytical techniques, including 1H-NMR, mass spectral, FT-IR spectra, UV-Vis, elemental analysis (C.H.N.S), measurement of electrical conductivity, magnetic susceptibility, TGA, XRD data and SEM spectra support azo ligand structures and their metal complex. The ligand is the trident N, N, O donor and forms the ML2 [metal-ligand] stoichiometry complex. Cd(II)-complex is found to have exhibited octahedral geometry. The ligand and its metal complex were screened against A. Niger for their antifungal activity and antibacterial activity against S. Aurores and E. Coli.

Pollution of industrial wastewaters containing dyes is a major concern for health in many countries, calling for advanced remediation techniques. Here, we review dye classification, toxicity, and removal with focus on adsorption using nanomaterials and magnetic nanoparticles. We present isotherm modeling and kinetic studies. We discuss factors controlling dye adsorption, such as pH, dye concentration, adsorbent amount, and temperature. Adsorption using magnetic nanoparticles appear as a simple and cost-effective technique. Removal efficiency increases with adsorbent concentration but declines sharply with increasing pH. Temperature is also highly influencing the removal.

The color removal activity of polyphenolic extracts obtained by maceration of coffee pulp with the Coffea arabica species was evaluated in synthetic waters prepared with three commercial dyes: methylene blue, malachite green and crystal violet. The extract was prepared by maceration using milled coffee pulp in a hydroalcoholic solution with a volume ratio of 1:1 and a solid: solvent ratio of 1:20 (g: mL). Additionally, total polyphenols were quantified using the Folin-Ciocalteu method and pH effects were evaluated based on the color removal percentages at fixed doses of 2.5 mg GAE / L (gallic acid equivalent per liter). Maximum removals with the values of 61.74%, 91.65% and 86.47% were obtained for malachite green, crystal violet and methylene blue at a pH of 4.26, 8.40 and 9.22, respectively. The present study confirms the potential use of waste extracts from the coffee industry for the removal of cationic dyes by coagulation.

The present study investigates the effects of substituents, structural rigidity, tautomerism, hydrogen bonding interaction, and spatial hindrance on the thermal stability of some azo compounds including bisazo Tröger base analogs (BATBAs). The relatively large structures of BATBAs allow assessing their thermal stability before reaching the sublimation or boiling point. BATBAs carry two identical azo groups per molecule resulting in an intense and detectable sign of decomposition. Unlike most azo dyes, BATBAs are not ionic and prevent the complexity of decomposition associated with simultaneous dehydration. A few commercial azo dyes are also analyzed to evaluate the generality of the conclusion.

Hünlich’s base modification has resulted in introducing a series of versatile Λ-shaped building blocks presented in this work. The methods are optimized to provide convenient approaches in the quicker production of these new building blocks in low-cost and low-risk.

The production of azo derivatives of a di-amino analogue of Tröger’s base (Hünlich base), by employing the standard procedures of diazotization, azo-coupling and Williamson etherification is described here. These versatile molecules possess a Λ-shaped core, photoswitchable groups and some carry two modifiable extremities to enable further synthesis or molecular assembly. The synthesis is straightforward and requires inexpensive starting materials, which facilitates their application to different fields of research such as light-driven molecular machine design.

The enantiomer separation of a chiral Tröger's base analog and its use, as an optically active building block, in the construction of molecular superstructures are presented. Various strategies are illustrated here for the attachment of azo photoswitches to the Tröger's base scaffold without racemizing its stereogenic centers. The resulting optically active photoswitches introduced chirality, thermochromic, and phototunable properties to an achiral liquid crystal host. The doped mesophases reflected specific wavelengths of light owing to the formation of self-organized helical superstructures. These observations illustrate the potential use of the presented products as liquid crystal dopants.

Aniline derivatives were diazotized and coupled with 3-aminocrotononitrile to give the corresponding 2-arylhydrazono-3-ketiminobutyronitriles. Cyclization of these arylhydrazono derivatives with hydrazine monohydrate afforded 5-amino-4-arylazo-3-methyl-1H-pyrazoles which were subsequently diazotised and coupled with malononitrile to yield a series of pyrazolylhydrazonomalononitriles. These compounds were then reacted with hydrazine monohydrate to provide 10, novel, heterocyclic disazo dyes, which were characterized by elemental analysis and spectral methods. The antimicrobial activity and absorption characteristics of the dyes were also examined in detail.

A new azo-chalcone ligand was prepared in this work, by preparation the amino-chalcone first followed by diazoted it and reacting with the coupling component (2-naphthol) at 0ºC to produce the new ligand (VACAN). Three chelating complexes of divalent transition metal ions (Co, Ni, Cu) were prepared after the fixation of optimal condition of (concentration and pH values)and determination the mole ratio (M:L),the result indicate that the mole ratio for Co 2+ ion was(2:1),while the others has (1:1)ratio. Both the amino-chalcone, the new ligand (VACAN) and its complexes was identified with the available techniques such (Mass spectroscopy (for VACAN), elementary analysis, Atomic Absorption, Uv-Visible spectroscopy, I.R spectroscopy), electrical molar conductivity and Magnetic susceptibility for the solid complexes. From the results obtained we can suggest an octahedral geometry for cobalt complex, square planner geometry for nickel complex and tetrahedral geometry for copper complex was appeared.

The batik industry is considered to be one of the largest textile cottage industries in the Southeast Asian region. Batik processing utilizes wax as a physical resistant and consumes a large amount of water during dyeing, fixing, and washing process; thus, generating harmful wastewater including dye, wax, and other auxiliaries. Respectively, an efficient wastewater treatment method is deemed necessary to meet legal emission standards. In this study, application of polyamide nano-membrane to remove dyes was evaluated for five different fiber reactive dyes' wastewater, namely reactive blue 15, reactive red 194, reactive yellow 145, reactive black 5, and reactive orange 16. The discussed dyes were tested in low concentration (16 mg/l) during a 60 min filtration process. The efficiency of filtration was calculated based on pre-process and post-process analytical experiments. The flux for all the samples ranged between 7.8 and 9.2 ml/cm(2 )s. The permeate pH value of the samples was observed to slightly increase, within a range of 6.4-7.1. Conductivity measurements for the samples indicated dramatic reduction for each sample dye solution compared to the sample from the feed to permeate during the filtration runs. Chemical oxygen demand value in the permeate samples was reduced to zero, representing a dye removal efficiency of more than 90%, thus successfully meeting the environmental legal standard.

Link to Full-Text Articles :
http://www.tandfonline.com/doi/pdf/10.1080/19443994.2014.912964

Pseudomonas species was isolated from the textile effluent polluted soil in Ankleshwar, Gujart, India and identified based on Biochemical and 16S RNA Sequence. The present study was carried out in an attempt to decolorize a commonly used yet tougher dye to decolorize, Reactive Black. The decolorization percentage was calculated from UV-Vis spectrophotometric analysis. Dye decolorization was probably due to the biotransformation and depended upon the biomass. Replacement of nutrient broth with minimal media did not show any decolorization property. The decolorization was confirmed by studying the spectral analysis of the dye. 16S rRNA partial gene sequencing (772 bp) of isolate Pseudomonas was also performed and a phylogenetic tree was prepared. Decolorization was optimized and found to be up to 95% at 7 pH, 40°C under static and non-aerated condition.

... Kraft E1 effluent (E1) corresponds to the first alkaline extraction stage. ... concentration is the collection of data that can be compared with those obtained in lignin peroxidase immobilisation ... were more satisfactory than those obtained by the use of free [35] or silica supported [17 ...

Congo red is a synthetic azo-dye dye with many industrial applications. The effluents containing azo dyes are causing several environmental hazards and thus should be treated prior to their discharge. The present work investigates the possible use of a novel microbial consortium from sheep compost for the decolorization of Congo red dye. The effect of different parameters including contact time, dye concentration and inoculum concentration on dye decolorization were investigated. The kinetic of dye decolorization was also assessed and the biodegradation of the dye was confirmed by different techniques. The results showed that the microbial consortium decolorized about 98% of Congo red (500 mg/L) after 24h. The efficiency of the decolorization decreased from 95% to 62% when the dye concentration increased from 100 to 500mg/L. Also, it was noticed that 75% of Congo red (25 mg/L) was decolorized at an inoculum rate of 2.5%. The kinetic results suggested that the decolorization of Congo...

The azo class of synthetic dyes represents one of the most industrially used dyes as well as a major class of environmental contaminants, which possess one or more azo bonds (-N=N-) along with aromatic rings and sulfonic groups. Due to its recalcitrant nature and toxicity for animals and human beings, the elimination of these dyes from the environment is essential. The present study focuses on the biodegradation of such azo dye, malachite green (MG), through a potent ligninolytic fungus, Aspergillus flavus (F10). Aspergillus flavus (F10) completely decolorized MG (150 mg L−1) within six to eight days in optimized Kirk's basal medium under static aerobic conditions at pH 5.8. Sucrose and sodium nitrate were efficient carbon and nitrogen sources, respectively. The products obtained after degradation were examined using UV-vis spectrophotometry, Fourier transform infrared spectroscopy, and liquid chromatography-mass spectroscopy. The metabolic intermediate products were identified as N-demethylated and N-oxidized metabolites, including primary and secondary arylamines, which confirms the involvement of laccase and manganese peroxidase in decolorization and degradation of MG. The end products of MG degradation were nontoxic. Aspergillus flavus (F10), immobilized by entrapment on natural and synthetic polymeric matrices was found to be a more efficient degrader of MG as compared to free cells.

Narrow-leaved cattails were studied in synthetic reactive dye wastewater (SRDW) under caustic conditions. The effects of the toxic dye were expressed in terms of relative plant growth rate and the appearance of symptoms such as necrosis, and chronic or acute wilting. The dye toxicity was 25.33 mg l(-1) which was close to approximate the concentration of dye residue from the textile effluent in the public stream. The system pH and % color removal were decreased, indicating that narrow-leaved cattail can treat wastewater. The average system pH decreased from 9 to 7. The maximum color removal was approximately 60% when cultured under soil conditions. The SEM image of narrow-leaved cattail root after treatment with SRDW indicated that the root cortex was damaged and the crystalline sodium salts deposited in the root cells which caused evaporation and transpiration decreased in SRDW. The salinity under caustic conditions also affects the growth of the plants. The maximum sodium removal was approximately 44% and was found in the SRDW under soil conditions within 14 days. A small amount of sodium could enhance the relative growth rate. However, the sodium removal of the plants was limited after the third week of treatment. It should be noted that narrow-leaved cattails are known to avoid the textile dye and salt stress conditions during SRDW treatment through special mechanisms such as salt accumulation in the roots or shedding of older leaves. In addition, elements such as silicon, calcium and iron in plants might help the plant to detoxify by forming complexes with dye molecules.

In the paper, equilibrium of sorption of s elected azo dyes onto natural sorbents was studied. The sorbents included birch chips, rye straw, hemp fiber and cellulose. The materials were first subjected to initial heat and chemical processing. Sorption studies were carried out for selected azo dyes, i.e. Reactive Blue 81, Reactive Red 120, Direct Black 22 and Direct Orange 26. An advanced examination under infrared light was performed for the analysed systems, which allowed for the determination of the nature of the dye-sorbent bond. In most cases, the bonds were a result of physical adsorption on the surface and in the micropores of the material.

This article describes the synthesis and characterization of azo derivatives of the Hünlich base. The possession of modifiable extremities, a Λ-shaped core, and photo-responsive groups are features of these novel products. Such materials may provide a handy tool-kit including a set of photoswitches with a specific response to external stimuli.

Pre Publish Master of Science Thesis

Estimated Relase Date : 30th July 2015

Mersin University The Graduate School of Natural and Applied Science  Department of Nanotechnology and Advanced Materials
Thesis Supervisor : Assoc. Prof. Dr. Meral TURABIK

A bacterial consortium was constructed using five different bacterial strains isolated from the effluent with the ability to degrade Acid Blue, a diazo dye. These organisms were identified as Pseudomonas putida (2 strains-designated as A & B), Bacillus subtillis, Pseudomonas aeruginosa (2 strains) using 16S rRNA analysis. The consortium was found to degrade 90% of the dye by 22 h in 80% diluted textile effluent supplemented with glucose and ammonium nitrate. Optimization studies using Response Surface Methodology have confirmed that the degradation process was predominantly influenced by agitation and pH where as glucose was found to have negative effect. TLC analyses indicated the presence of metanilic acid and peri acid in 24 h sample which disappeared by 48 h. The GC-MS analysis has confirmed the presence of methyl salicylic acid, catechol and β-ketoadipic acid with the RT values of 7.71, 10.88 and 15.04 respectively confirming the complete degradation of Acid Blue.

Bacterial isolates, obtained from dye-contaminated sludge, decolorized the toxic azo dye methyl red (MR). Enterobacter spp. ETL-1979 was selected because of its better abilities to completely decolorize MR under aerobic conditions. Effects of physicochemical parameters (temperature, stirring, concentration of glucose and pH of the synthetic medium) on the MR decolorization by the selected bacterium were studied. Under optimal conditions, Enterobacter spp. ETL-1979 completely decolorized 100 mg/l of MR within 6 h of incubation in synthetic medium. The high MR decolorization ability and low nutrient and environmental requirements of Enterobacter spp. ETL-1979 enable this bacterium to be used in the biological treatment of industrial effluent containing azo dyes.