Synthesis and investigation of antimicrobial activity and spectrophotometric and dyeing properties of some novel azo disperse dyes based on naphthalimides

A series of novel disperse dyes containing azo group were synthesized through a diazotization and coupling process. The 4‐amino‐N‐2‐aminomethylpyridine‐1,8‐naphthalimide was diazotized by nitrosylsulphuric acid and coupled with various aromatic amines such as N,N‐diethylaniline, N,N‐dihydroxyethylaniline, 8‐hydroxyquinoline, and 2‐methylindole. Chemical structures of the synthesized dyes were characterized by Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), proton nuclear magnetic resonance (¹H NMR), carbon nuclear magnetic resonance (¹³C NMR), elemental analysis, and ultraviolet–visible (UV–visible) spectroscopy. The spectrophotometric data of all dyes were evaluated in various solvents with different polarity. Eventually, the dyes were applied on polyamide fabrics in order to investigate their dyeing properties. The fastness properties of the dyed fabrics such as wash, light, and rubbing fastness degrees were measured by standard methods. Moreover, the color gamut of the synthesized dyes was measured on polyamide fabrics. Results indicated that some of the synthesized dyes were able to dye polyamide fabrics with deep shades. They had very good wash and rubbing fastness degrees and moderate‐to‐good light fastness on polyamide fabrics. The antibacterial and antifungal activities of the synthesized dyes were evaluated in soluble state and on the dyed fabrics. The results indicated that dye 2 containing N,N‐dihydroxyethylaniline as coupler had the highest activity against all the bacteria and fungi used. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:1086–1095, 2015     

The microbial degradation of azo dyes: minireview

The removal of dyes in wastewater treatment plants still involves physical or chemical processes. Yet numerous studies currently exist on degradation based on the use of microbes—which is a well-studied field. However progress in the use of biological methods to deal with this environmentally noxious waste is currently lacking. This review focuses on the largest dye class, that is azo dyes and their biodegradation. We summarize the bacteria identified thus far which have been implicated in dye decolorization and discuss the enzymes involved and mechanisms by which these colorants are broken down.     

The reaction between some dyes and synthetic hydroxyapatite I. The uptake of dyes in relation to their structures

Synopsis The uptake of dyes from dilute solutions by synthetic hydroxyapatite and other sparingly soluble calcium compounds has been determined. About 30 dyes, mostly azo-, dis-azo and anthraquinonoid types were used in 95% ethanol or 0.1 M tris buffer. Many had closely related configurations. Chemical groupings possibly responsible for the adsorption of particular dyes by hydroxyapatite have been deduced from an analysis of the results. The uptake of most dyes from alcoholic solutions was, linearly related to the surface area of hydroxyapatite. Calcium carbonate and secondary calcium phosphate took up less stain than hydroxyapatite of similar surface area. With the simpler anthraquinonoid dyes, the uptake was higher from aqueous than alcoholic solutions, but specificity for hydroxyapatite was much less. The increased uptake of dye by powdered bone or dentine when rendered anorganic was proportional to the increased surface area. It was found that several dyes in common use as stains for bone and calcified tissue were only poorly adsorbed by synthetic hydroxyapatite under the particular conditions of these experiments.The experimental data presented could be used as a basis for the development of histochemical reactions for calcified tissue or inclusions. By suitable choice of dyes, solvent and rinsing solution it ought to be possible to differentiate various forms of calcified material.     

Bacterial decolorization and degradation of azo dyes

Azo compounds constitute the largest and the most diverse group of synthetic dyes and are widely used in a number of industries such as textile, food, cosmetics and paper printing. They are generally recalcitrant to biodegradation due to their xenobiotic nature. However microorganisms, being highly versatile, have developed enzyme systems for the decolorization and mineralization of azo dyes under certain environmental conditions. Several genera of Basidomycetes have been shown to mineralize azo dyes. Reductive cleavage of azo bond, leading to the formation of aromatic amines, is the initial reaction during the bacterial metabolism of azo dyes. Anaerobic/anoxic azo dye decolorization by several mixed and pure bacterial cultures have been reported. Under these conditions, this reaction is non-specific with respect to organisms as well as dyes. Various mechanisms, which include enzymatic as well as low molecular weight redox mediators, have been proposed for this non-specific reductive cleavage. Only few aerobic bacterial strains that can utilize azo dyes as growth substrates have been isolated. These organisms generally have a narrow substrate range. Degradation of aromatic amines depends on their chemical structure and the conditions. It is now known that simple aromatic amines can be mineralized under methanogenic conditions. Sulfonated aromatic amines, on the other hand, are resistant and require specialized aerobic microbial consortia for their mineralization. This review is focused on the bacterial decolorization of azo dyes and mineralization of aromatic amines, as well as the application of these processes for the treatment of azo-dye-containing wastewaters.     

The toxicity of textile reactive azo dyes after hydrolysis and decolourisation

The toxicity of C.I. Reactive Black 5 and three Procion dyes, as found in textile effluents, was determined using the bioluminescent bacterium Vibrio fischeri. Hydrolysed Reactive Black had a slightly greater toxicity than the parent form (EC(50) 11.4+/-3.68 and 27.5+/-4.01 mg l(-1), respectively). A baffled bioreactor with anaerobic and aerobic compartments was used to decolourise hydrolysed Reactive Black 5 in a synthetic effluent. Decolourisation of hydrolysed Reactive Black resulted in an increased toxicity (EC(50) 0.2+/-0.03 mg l(-1)). Toxicity was not detectable when decolourised Reactive Black 5 was metabolised under aerobic conditions. No genotoxicity was detected after the decolourisation of either the parent or the hydrolysed reactive dyes, either in vitro or in the bioreactor. The toxicity and genotoxicity of decolourised C.I. Acid Orange 7 was due to the production of 1-amino-2-naphthol (EC(50) 0.1+/-0.03 mg l(-1)).     

The effect of azo dyes on heat aggregation of IgG

The mechanism of IgG heat aggregation was studied using IgG aggregates complexed with azo dyes to increase their solubility and stability. Heat dependent and heat independent steps of aggregation were differentiated. On heating IgG at the dye concentration exceeding 100 times that of protein, mainly dimers are formed, as judged from ultracentrifugation and chromatographic analysis, whereas high molecular weight derivatives appear at room temperature when the protein/dye ratio is decreased. The analysis of spectral changes following either the attachment or removal of the dye from IgG aggregates implies that only a part of the dye molecules is bound firmly and directly to the protein binding sites. These dye molecules which are easily removed by adsorption to cellulose or reduced by dithionate but migrate together with IgG aggregates on chromatography and electrophoresis, are supposed to constitute that part of the micelle which extrudes from the binding site and, hence, is fixed indirectly to protein. Various proteins with predominant beta-structure were also found to bind azo dyes when heated.     

Toxicity assessment and microbial degradation of azo dyes

Toxic effluents containing azo dyes are discharged from various industries and they adversely affect water resources, soil fertility, aquatic organisms and ecosystem integrity. They pose toxicity (lethal effect, genotoxicity, mutagenicity and carcinogenicity) to aquatic organisms (fish, algae, bacteria, etc.) as well as animals. They are not readily degradable under natural conditions and are typically not removed from waste water by conventional waste water treatment systems. Benzidine based dyes have long been recognized as a human urinary bladder carcinogen and tumorigenic in a variety of laboratory animals. Several microorganisms have been found to decolourize, transform and even to completely mineralize azo dyes. A mixed culture of two Pseudomonas strains efficiently degraded mixture of 3-chlorobenzoate (3-CBA) and phenol/cresols. Azoreductases of different microorganisms are useful for the development of biodegradation systems as they catalyze reductive cleavage of azo groups (-N=N-) under mild conditions. In this review, toxic impacts of dyeing factory effluents on plants, fishes, and environment, and plausible bioremediation strategies for removal of azo dyes have been discussed.     

Biodegradation perspectives of azo dyes by yeasts

Azo dyes are the largest class of synthetic dyes, which are widely used in the textile industry. The amount of dyestuff does not bind to the fibers and is lost in wastewater during textile processing. The discharge of colored effluents into the environment is not only aesthetically unpleasing. Moreover, dyes and their break-down products cause toxic effects and they affect photosynthetic activity of aquatic systems by reducing light penetration. A number of microorganisms belonging to different taxonomic groups of bacteria, algae, fungi and yeast have been reported for their ability to decolorize azo dyes. In the literature the ability to decolorize azo dyes by yeasts, compared to bacterial and fungal species, has been studied in a few reports. Within this review, an attempt is made to elucidate some basic biological aspects associated with the azo dye degradation by yeasts and enzymes involved that are responsible for degradation process.     

Decolorization of azo dyes by Geobacter metallireducens

Geobacter metallireducens was found to be capable of decolorizing several azo dyes with different structures to various extents. Pyruvate, ethanol, acetate, propionate, and benzoate could support 66.3?±?2.6?93.7?±?2.1 % decolorization of 0.1 mM acid red 27 (AR27) in 40 h. The dependence of the specific decolorization rate on AR27 concentration (25 to 800 μM) followed Michaelis–Menten kinetics (K _m?=?186.9?±?1.4 μΜ, V _max?=?0.65?±?0.02 μmol?mg protein^?1 h^?1). Enhanced AR27 decolorization was observed with the increase of cell concentrations ranging from 7.5 to 45 mgL^?1. AR27 decolorization by G. metallireducens was retarded by the presence of goethite, which competed electrons with AR27 and was reduced to Fe(II). The addition of low concentrations of humic acid (1?100 mgL^?1) or 2-hydroxy–1,4-naphthoquinone (0.5?50 μM) could improve the decolorization performance of G. metallireducens. High-performance liquid chromatography analysis suggested reductive pathway to be responsible for decolorization. This was the first study on azo dye decolorization by Geobacter strain and might improve our understanding of natural attenuation and bioremediation of environments polluted by azo dyes.     

Decolorization of azo dyes by Rhodobacter sphaeroides

Rhodobacter sphaeroides AS1.1737 decolorized more than 90% of several azo dyes (200 mg dyes l^–1) in 24 h. The optimal culture conditions were: anaerobic illumination (1990 lx), peptone as carbon source, temperature 35–40 °C and pH 7–8. Intracellular crude enzyme from this strain had azoreductase activity, optimized temperature as 45–50 °C, and decolorization kinetics which were consistent with a ping-pong mechanism.     

Binding of textile azo dyes byMyrothecium verrucaria

Summary A strain ofMyrothecium verrucaria that showed a high capacity for rapid decolorization of textile dye solutions was isolated from soil. As much as 70%, 86%, and 95% of Orange II, 10B (blue) and RS (red) dyes (color index no. 15510, 20470, 23635), respectively, were adsorbed from solutions of approximately 0.2 g dye per liter in 5 h by approximately 4.5 g dry weight of cells per liter of dye solution. Intact cells showed a higher adsorption capacity than disrupted cells for Orange II and RS but not for 10B. Dye bound to cells was recoverable by extraction with methanol and methanol-treated cells were able to be recycled, albeit with a slightly diminished dye-binding capacity. The Tween detergents were shown to reduce dye adsorption. Dyes strongly bound to the fungal biomass required sonication in dH₂O or in Triton X-100 or extraction with methanol for their removal. These results suggest that hydrophobic/hydrophilic interactions are important in dye binding.     

The significance of azo-reduction in the mutagenesis and carcinogenesis of azo dyes

Azo dyes are widely used in textile, printing, cosmetic, drug and food-processing industries. They are also used extensively in laboratories as either biological stains or pH indicators. The extent of such use is related to the degree of industrialization. Since intestinal cancer is more common in highly industrialized countries, a possible connection may exist between the increase in the number of cancer cases and the use of azo dyes. Azo dyes can be reduced to aromatic amines by the intestinal microflora. The mutagenicity of a number of azo dyes is reviewed in this paper. They include Trypan Blue, Ponceau 3R, Pinceau 2R, Methyl Red, Methyl Yellow, Methyl Orange, Lithol Red, Orange I, Orange II, 4-Phenylazo-Naphthylamine, Sudan I, Sudan IV, Acid Alizarin Violet N, Fast Garnet GBC, Allura Red, Ponceau SX, Sunset Yellow, Tartrazine, Citrus Red No. 2, Orange B, Yellow AB, Carmoisine, Mercury Orange, Ponceau S, Versatint Blue, Phenylazophenol, Evan's Blue and their degraded aromatic amines. The significance of azo reduction in the mutagenesis and carcinogenesis of azo dyes is discussed.     

假单胞菌S—42对偶氮染料的脱色和降解代谢

Pseudomonas S-42 was capable of decolorizing azo dyes such as Diamira Brilliant Orange RR(DBO-RR), Direct Brown M (DBM), Eriochrome Brown R(EBR) and so on. The cell suspension, cell-free extract and purified enzyme of Pseud. S-42 could decolorize azo dyes under similar conditions: the optimum pH and temperature laid 7.0 and 37 degrees C respectively. The efficiencies of decolorizing of DBO-RR, DBM, EBR by intact cells stood more than 90%. When the cell concentration was 15 mg(wet)/ml and the reaction time was 5 hours, the decolorizing activity for above three azo dyes by intact cells were 1.75, 2.4, 0.95 micrograms dye/mg cell, respectively. Cell-free extract and purified enzyme could well express the decolorizing activity only under the anaerobic condition and added NADH. Purified enzyme belongs to azoreductase, its molecular weight is about 34,000-2000 daltons, and its Vmax and Km for DBO-RR are 13 mumol.mg protein-1.min-1 and 54 mumol/L. The results of the detection of the biodegrading products of DBO-RR by spectrophotometric and NaNO2 reactional methods showed that the biodegradation of azo dyes was initiated by the reduction cleavage of azo bonds. It was hypothesized that biodegrading metabolism pathway of DBO-RR by Pseudomonas S-42.     

Degradation of azo dyes by laccase and ultrasound treatment

The goal of this work was to investigate the decomposition of azo dyes by oxidative methods, such as laccase and ultrasound treatments. Each of these methods has strong and feeble sides. The laccase treatment showed high decolorization rates but cannot degrade all investigated dyes (reactive dyes), and high anionic strength led to enzyme deactivation. Ultrasound treatment can decolorize all tested dyes after 3 h at a high energy input, and prolonged sonication leads to nontoxic ionic species, which was demonstrated by ion chromatography and toxicity assays. For the first time, it was shown that a combination of laccase and ultrasound treatments can have synergistic effects, which was shown by higher degradation rates. Bulk light absorption and ion-pairing high-performance liquid chromatography (IP-HPLC) were used for process monitoring, while with reversed-phase HPLC, a lower number of intermediates than expected by IP-HPLC was found. Liquid chromatography-mass spectrometry indicated that both acid orange dyes lead to a common end product due to laccase treatment. Acid Orange 52 is demethylated by laccase and ultrasound treatment. Further results confirmed that the main effect of ultrasound is based on *OH attack on the dye molecules.     

Biodegradation of azo and heterocyclic dyes by Phanerochaete chrysosporium

Biodegradation of Orange II, Tropaeolin O, Congo Red, and Azure B in cultures of the white rot fungus, Phanerochaete chrysosporium, was demonstrated by decolarization of the culture medium, the extent of which was determined by monitoring the decrease in absorbance at or near the wavelength maximum for each dye. Metabolite formation was also monitored. Decolorization of these dyes was most extensive in ligninolytic cultures, but substantial decolorization also occurred in nonligninolytic cultures. Incubation with crude lignin peroxidase resulted in decolorization of Azure B, Orange II, and Tropaeolin O but not Congo Red, indicating that lignin peroxidase is not required in the initial step of Congo Red degradation.     

Biodegradation of azo and anthraquinone dyes in continuous systems

The purpose is to develop a complete microbiological model system for the treatment of wastewater from textile mills in developing countries. Artificial wastewater was treated by microorganisms growing on wood shavings from Norway spruce during unsterile conditions. The microorganisms were inoculated from forest residues. Mixtures of the azo dyes Reactive Black 5 and Reactive Red 2 were degraded in batch as well as continuous experiments. Reactive Red 2 mixed with the anthraquinone dye Reactive Blue 4 was also treated in the continuous system. The system consisted of three reservoirs - the first two with an anaerobic environment and the third with an aerobic. The dye concentrations were 200 mg l⁻¹ of each dye in the continuous system and the retention time was approximately 4 days and 20 h per reservoir. Samples from the process were analysed with spectrophotometer and LC/MS to monitor the degradation process. 86-90% of the colour was removed after a treatment of 4 days and 23 h in the continuous process. Two metabolites were found in the outlets of reactors one and two, but they were degraded to below the detection limit in the aerobic reactor.     

Mutagenicity of azo dyes: structure-activity relationships.

Azo dyes are extensively used in textile, printing, leather, paper making, drug and food industries. Following oral exposure, azo dyes are metabolized to aromatic amines by intestinal microflora or liver azoreductases. Aromatic amines are further metabolized to genotoxic compounds by mammalian microsomal enzymes. Many of these aromatic amines are mutagenic in the Ames Salmonella/microsomal assay system. The chemical structure of many mutagenic azo dyes was reviewed, and we found that the biologically active dyes are mainly limited to those compounds containing p-phenylenediamine and benzidine moieties. It was found that for the phenylenediamine moiety, methylation or substitution of a nitro group for an amino group does not decrease mutagenicity. However, sulfonation, carboxylation, deamination, or substitution of an ethyl alcohol or an acetyl group for the hydrogen in the amino groups leads to a decrease in the mutagenic activity. For the benzidine moiety, methylation, methoxylation, halogenation or substitution of an acetyl group for hydrogen in the amino group does not affect mutagenicity, but complexation with copper ions diminishes mutagenicity. The mutagenicity of benzidine or its derivatives is also decreased when in the form of a hydrochloride salt with only one exception. Mutagenicity of azo dyes can, therefore, be predicted by these structure-activity relationships.