Disazo Dyes Research Articles

Active manganese oxide: a novel adsorbent for treatment of wastewater containing azo dye

A new variety of active manganese oxide was prepared, characterized, and tested for its potential of adsorbing Congo Red, a dis-azo dye, from aqueous solutions. Both equilibrium and kinetics were investigated over different values of process parameters such as temperature (25-45 degrees C), adsorbent loading (0.4-0.6%), initial dye concentration (50-500 mg/L), presence of salts (sodium sulphate, 500 mg/L) and the oxygen content (MnO(x), x=1.2, 1.33 and 2) of the adsorbent. The equilibrium adsorption data were fitted to Langmuir and Freundlich isotherms. Langmuir adsorption capacity of the sorbent (x=1.33) for Congo Red was 38.6 mg/g at room temperature which is substantially higher than those for commercial manganese dioxide, red mud, coir pith, activated carbon, and fly ash. The kinetic data were best interpreted using a pseudo-second order model. The results show that the active manganese oxide used in this work removes the dye by reversible adsorption and has the potential for practical use for remediation of textile industry effluents.

The synthesis, spectroscopic properties and theoretical calculation of some novel disperse disazo dyes derived from 3-amino-5-hydroxy-1-phenylpyrazole

In this study 5-amino-4-arylazo-3-methyl-1H-pyrazoles ( 1a– 1m) were diazotised and coupled with 3-amino-5-hydroxy-1-phenylpyrazole to give disperse disazo dyes ( 2a– 2m). The newly synthesized 13 disperse disazo dyes were characterized by elemental analysis and spectral methods. The solvatochromic behaviour of these disperse disazo dyes in various solvents was evaluated. Substituent, acid and base effects on the visible absorption spectra of the disperse disazo dyes substituted with electron-withdrawing and electron-donating groups at their o-, m-, p-position were also reported in detail. Additionally, theoretical calculations are performed for the disazo dyes. The molecular geometry and chemical shift are calculated by using ab initio calculations based on the density functional theory (DFT) in the ground state. The results obtained are in agreement with the experimental results.

Decolourization of textile dyes by the white-rot fungiPhanerochaete chrysosporiumandPleurotus ostreatus

BACKGROUND: The ability of the fungi Pleurotus ostreatus and Phanerochaete chrysosporium to decolourize and detoxify 11 (mono-, dis-, poly- azo, and anthraquinonic type) dyes, widely used across the textile and leather industries, was tested. RESULTS: Different substrate specificities were revealed between P. ostreatus and P. chrysosporium in decolourization experiments. The latter fungus provided almost complete decolourization of the tested azo dyes up to 600 ppm and dis-azo dyes up to 1000 ppm, and 80% decolourization of the tris-azo dye DBU1L38 at 1000 ppm, after 6 days. P. ostreatus provided almost total decolourization of the anthraquinone type dye ABU62 (1000 ppm) after just 1 day. P. ostreatus also showed the ability to decolourize the tested dis-azo and tris-azo dyes, giving the best performances against the dis-azo DBU1U1 (600 ppm) dye, which was 100% decolourized after 6 days. Laccases proved to be the main enzymatic activities acting in P. ostreatus decolourization. CONCLUSION: The potential of the fungi P. ostreatus and P. chrysosporium as efficient bio-systems for decolourization and detoxification of several toxic industrial dyes was demonstrated. The role of laccases in the decolourization of dis-azo dyes by P. ostreatus was demonstrated for the first time. Copyright © 2008 Society of Chemical Industry

Synthesis and application of alkyl-substituted disazo yellow dyes for unmodified polypropylene fiber

The several disazo dyes having different alkyl substituents were synthesized to dye unmodified polypropylene fiber. The affinity of the dyes onto unmodified polypropylene was increased with the increase of the length of alkyl substituents. Therefore, the heptyl-substituted dye having the longest alkyl group in this experiment showed very high color strength of dyeings with K/S value of over 24 at maximum absorption wavelength. The color fastnesses to washing, rubbing and light were also improved significantly for the longer alkyl substituted dyes, so that the heptyl-substituted dye exhibited a rating of 4∼5 for all kinds of fastnesses.

Investigation of ground state tautomeric form of a heterocyclic disazo dye derived from barbituric acid by ab initio Hartree–Fock and density functional theory calculations

The optimized molecular structures, vibrational frequencies and corresponding vibrational assignments of 10 tautomeric forms of a heterocyclic disazo dye [5-(3-methyl-4-phenylazo-1H-pyrazole-5-ylazo) barbituric acid] have been calculated using ab initio Hartree–Fock (HF) and density functional theory (B3LYP) methods with 6-31G(d, p) basis set level. Calculations have shown that the most probably preferential form of the heterocyclic disazo barbituric acid dye in the ground state is azo-hydrazo-keto form corresponding to the experimental results.

The synthesis, antimicrobial activity and absorption characteristics of some novel heterocyclic disazo dyes

Abstract 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.

Synthesis, spectral characterisation and antimicrobial activity of new disazo dyes derived from heterocyclic coupling components

Two series of new disazo dyes were prepared by diazotising 4,4′‐diaminodiphenylsulphonamide and 4,4′‐diaminodiphenylurea and coupling with 3‐methyl‐1‐phenyl‐pyrazoline‐5‐one, 2‐methylindole, 8‐hydroxyquinoline, 2‐phenylindole, 1‐methyl‐2‐phenylindole, 3‐amino‐1‐phenyl‐pyrazoline‐5‐one. These dyes were characterised by ultraviolet–visible, Fourier transform infrared, nuclear magnetic resonance spectroscopic techniques and elemental analysis. The spectral characterisation of the dyes was evaluated with respect to visible absorption properties in various solvents. The effects of acid and base on the visible absorption maxima of the dyes were also reported. In addition, the antimicrobial effect of the dyes was evaluated.

Aeration as a factor in textile dye bioremoval by Aspergillus niger

Experiments were done to study the bioremoval/ biosorption of dis-azo dye byAspergillus niger strain 20 in two concentrations using 5 liter bioreactor at five aeration rates. The experimental results are compared for various operating conditions. The dye used was direct brown and the inlet air flow rate was: 1/8, ¼, ½, 1, 2 v/v/min. The aeration rate of ½ v/v/min yielded 9.2 g fungal biomass and removed 72 % of the dye. Increasing of the aeration rate to 2 v/v/min increased the removal to 77%, whereas the biomass was decreased markedly at the end of the incubation time. The results also indicate that the fungal biomass obtained at the three other air flow rates was more or less the same after 3 days of incubation. The obtained results indicate that air flow rates 1/8, ¼ and ½ v/v/min gave better dye bioremoval as compared with the high aeration rate (1, 2 v/v/min) and can be recommended for dis-azo dye bioremediation. Isotherm experiments were conducted to determine the sorbents-desorption behavior of examined dye from aqueous solutions using Langmiur and Freundlich equations. Key words: Textile dyes, removing, dis-azo, batch reactor, modeling, bioremediation.

Preparation of Dis-Azo Dyes Derived from p-Aminophenol and Their Fastness Properties for Synthetic Polymer-Fibres

Preparation of Dis-Azo Dyes Derived from p-Aminophenol and Their Fastness Properties for Synthetic Polymer-Fibres

The synthesis, characterization and spectral properties of crown ether based disazo dyes

A series of crown ether based azo dyes ( 7a– 10) were obtained by the coupling of crown ether based diazonium chloride with various substituted naphthols ( 3a– 3f), pyrazolones ( 4a– 4d), acetoacetanilides ( 5a– 5d) and barbituric acid ( 6). The synthesized dyes were purified and characterized by elemental analysis, FT-IR, 1H NMR and FAB mass spectra. The absorption properties of the synthesized dyes were studied and their application in solvent based inks was investigated; the fastness properties of formulated inks were also studied.

The synthesis and solvatochromic properties of some novel heterocyclic disazo dyes derived from barbituric acid

5-Amino-4-arylazo-3-methyl-1 H-pyrazoles were diazotised and coupled with barbituric acid to provide 13 novel heterocyclic disazo barbituric acid dyes that were characterized by elemental analysis and spectral methods. The effects of varying the pH and solvent on the absorption of the dyes substituted with electron-withdrawing and electron-donating groups at their o-, m-, p-position were examined in detail.

Potential of aquatic fungi derived from diverse freshwater environments to decolourise synthetic azo and anthraquinone dyes

A total of 37 strains of aquatic hyphomycetes and 95 fungal isolates derived from diverse freshwater environments were screened on agar plates for the decolourisation of the disazo dye Reactive Black 5 and the anthraquinone dye Reactive Blue 19. The decolourisation of 9 azo and 3 anthraquinone dyes by 9 selected aquatic fungi was subsequently assessed in a liquid test system. The fungi were representatives of mitosporic anamorphs, and 6 strains had proven ascomycete affiliations. For comparison, 5 white rot basidiomycetes were included. The majority of dyes were decolourised by several mitosporic aquatic isolates at rates essentially comparable to those observed with the most efficient white rot fungus. Under certain conditions, particular aquatic strains decolourised dyes even more efficiently than the best performing white rot basidiomycete. Upon fungal treatment of several dyes, new absorbance peaks appeared, indicating biotransformation metabolites. All together, these results point to the potential of fungi occurring in freshwater environments for the treatment of dye-containing effluents.

The effects of reductant and carbon source on the microbial decolorization of azo dyes in an anaerobic sludge process

The effects of a reductant and carbon source on the decolorization of the disazo dye C.I. Reactive Black 5 and real textile wastewater were investigated in an anaerobic sludge system. The color removal without sulfide in this process was about 94% at 35 °C during 72 h. The intermittent addition of sulfide (10 mg/L) led to an increase in the microbial decolorization of more than 9% during 48 h in comparison with the case where no sulfide was added. The LC/MS and spectrophotometric analysis indicated that the microbial decolorization of the azo dye with anaerobic sludge was attributed to the reduction of the azo bonds. The decolorization rates were about 40% without an additional substrate and about 20% with methanol (10 −3 M), which were about 2- to 3-fold lower than that obtained with the favorite C-source, glucose. In the treatment of real textile wastewater, the unsatisfactory removal of COD (57.8%) and color was obtained during 12 h, due to the lack of readily degradable COD for the azo dye decolorization and the toxic effect of the wastewater.

Synthesis and absorption spectra of some novel heterocyclic disazo dyes derived from pyridone and pyrazolone derivatives

Heterocyclic amines were diazotized and coupled with 3-aminocrotononitrile to give the 2-hetarylhydrazone-3-ketiminobutyronitrile ( 1a– 1e) which can react with hydrazine hydrate and phenylhydrazine to afford the corresponding 5-amino-3-methyl-4-hetarylazo-1H-pyrazoles and 5-amino-3-methyl-4-hetarylazo-1-phenylpyrazoles ( 2a– 2j), respectively. Then, some novel disazo dyes 3a– 3j and 4a– 4j were synthesized by diazotisation of 5-amino-3-methyl-4-hetarylazo-1H-pyrazoles and 5-amino-3-methyl-4-hetarylazo-1-phenylpyrazoles using nitrosyl sulphuric acid, coupling with 3-cyano-6-hydroxy-4-methyl-2-pyridone and 3-methyl-1H-pyrazole-5-one. The dyes were characterized by elemental analysis and spectral methods and the solvatochromic behaviour of the dyes in various solvents was evaluated. Substituent, acid and base effects on the visible absorption maxima of the dyes were also reported.

Acid/Base Properties and Adsorption of an Azo Dye on Coating Pigments

Adsorption of an anionic disazo dye, Food Black 2 on coating pigments from polar solvents was studied. Pigments (kaolin, precipitated CaCO3, amorphous SiO2, TiO2, Al2O3, and talc) were chosen to be representative of those used in paper for ink‐jet printing. The predominating driving force for the adsorption was electrostatic interactions for all the pigments except talc, for which hydrophobic interactions were dominant. Lewis acid‐base properties of the pigments were studied by measuring adsorption of Lewis acid‐probe molecules from both polar and nonpolar media. The pigments studied were found to be amphoteric, containing both acidic and basic surface groups. However, in the presence of polar solvents, the adsorption of acid‐base probe molecules was greatly reduced, which indicates that Lewis acid‐base interactions have only a small influence on the adsorption of azo dyes from polar media such as water.

A facile synthesis of some new pyrazolo[1,5- a]pyrimidine heterocyclic disazo dyes and an evaluation of their solvatochromic behaviour

Hetarylmalononitriles (thiazolylmalononitrile and benzothiazolylmalononitrile) were prepared by the coupling reaction of malononitrile with heterocyclic amines in nitrosyl sulfuric acid. 4-Hetarylazo-3,5-diaminopyrazole compounds were obtained by the reaction of hetarylmalononitriles with hydrazine hydrate (64%). Both compounds can react with arylazo- and hetarylazomalononitriles to give 3,6-di-(aryl or hetaryl)-azo-2,5,7-triaminopyrazolo[1,5- a]pyrimidine heterocyclic disazo dyes. These dyes were characterized by elemental and spectral analyses (IR, 1H NMR and mass). The solvatochromic behaviour in various solvents was evaluated.

Decolorization of Copper Formazan Dyes and Disazo Dyes by Bilirubin Oxidase

Decolorization of Copper Formazan Dyes and Disazo Dyes by Bilirubin Oxidase

Synthesis and properties of some disazo disperse dyes derivatives of 2-amino-6-phenylazobenzothiazole and 2-amino-6-(4′-nitro)-phenylazobenzothiazole

This paper is concerned with the synthesis and evaluation of some red, violet and bluish violet disperse disazo dyes. They were synthesised via diazotisation of 2-amino-6-phenylazobenzothiazole or its nitro-substituted analogue followed by the coupling with a variety of coupling components. The spectral properties ( 1H NMR and visible spectra) of obtained dyes are reported. The basic fastness properties (light fastness, dry-heat treatment fastness) of the dyes on polyester fibre are also discussed in terms of their chemical structure.

Spectral-Polarization Properties and Light Resistance of Polyvinyl-Alcohol Films Colored With Disazo Dyes

Polarizers containing disazo dyes from the group of azobenzene-azonaphthalene have been developed. It has been established that their polarizing ability is determined by the mutual disposition of the azo group and electron-donor substituents in the naphthalene ring. On diazo coupling of γ acid into the α position relative to the oxy group, the M1 and M3 dyes are formed, the polarizing ability of which in uniaxially oriented polyvinyl-alcohol films is higher than in the M2 dye produced as a result of diazo coupling into the α position relative to the amino group. On irradiation by UV light, the dyes are subjected to photodestruction, which, in the case of M2, proceeds through trans-cis-isomerization. The rate of photodestruction depends on the aggregation of the dye molecules, and it increases in the presence of a free-radical initiator. The UV absorber (substituted benzotriazole) and the uniaxial orientation of the film retard this process.

Synthesis of disazo dyes derived from heterocyclic components

In this study, 2-phenylhydrazone-3-ketiminobutyronitrile was synthesised and reacted with hydrazine hydrate and phenylhydrazine to afford the corresponding 5-amino-3-methyl-4-phenylazo-1H-pyrazole and 5-amino-3-methyl-4-phenylazo-1-phenylpyrazole, respectively. Ten novel disazo dyes were then synthesised by diazotisation of 5-amino-3-methyl-4-phenylazo-1H-pyrazole and 5-amino-3-methyl-4-phenylazo-1-phenylpyrazole using nitrosylsulphuric acid, and coupling with 4-hydroxy-6-methyl-2-pyrone, 4-hydroxycoumarin, 3-methyl-1H-pyrazolin-5-one, 3-methyl-1-phenylpyrazolin-5-one and 3-cyano-6-hydroxy-4-methyl-2-pyridone. The dyes were characterised by elemental analysis and spectral methods. The solvatochromic behaviour of these disazo dyes in various solvents was evaluated. Received: 18 May 2005; Accepted: 8 July 2005.