Industrial Azo Dye Research Articles

Application of Photoelectro-Fenton/BDD Process Based on the Cathodic Production of H2O2 for Degradation of Industrial Dyes

Photoelectro-Fenton/BDD process promotes in situ hydrogen peroxide (H2O2) by means of oxygen reduction via two electrons, adding Fe2+ to the solution resulting in the production of free hydroxyl radicals (•OH). The reaction can be catalyzed by the UV ligth accelerating the degradation of organic compounds in solution, because it promotes the photocehmical regeneration of Fe2+, and as a result a major •OH radicals production. In the present work, the authors discussed the study of the H2O2 production over boron doped diamond (BDD) cathode and the degradation of two industrial azo dyes, Blue-BR (B-BR) and Black-TRS (B-TRS) by photoelectro-Fenton/BDD (PEF/BDD) process using UV-ligth source. Comparative electrolyses carried out with 3L filter press pilot plant equipped with a BDD anode and cathode at constant current density showed the superiority of the processes with BDD because of the higher oxidation ability of ·OH formed from water oxidation at the BDD surface. Total mineralization was rapidly reached for the most potent treatment of PEF with BDD due to the additional oxidation by ·OH produced from Fenton's type reaction between added Fe2+ (0.5mM) and H2O2 generated at the cathode. Azo dyes decay always followed a pseudo-first-order kinetics. The influence of current density and substrate concentration on PEF with BDD was examined.

Three different clay-supported nanoscale zero-valent iron materials for industrial azo dye degradation: A comparative study

For evaluation of oxidative degradation of industrial azo dye Rosso Zetanyl B-NG (RZ B-NG), three clay supported nanoscale zero-valent iron materials were synthesized: bentonite, kaolin and native clay-supported nanoscale zero-valent iron (B-nZVI, K-nZVI and NC-nZVI). All clays used as a support material not only dispersed and stabilized nanoscale zero valent iron (nZVI) but also improved the adsorption and degradation of dye as they consequently improved heterogeneous Fenton oxidation. Under the optimal conditions, for the used nanomaterial concentrations of 112, 168 and 224mg/L for B-nZVI, NC-nZVI and K-nZVI, the decolourization efficiencies achieved were 92.7, 92.1 and 91.6% and appropriate TOC removals were 57.8, 57.2 and 50.7% in the same order. The best catalytic performance was exhibited when B-nZVI was used. These results correlate with the specific surface area and mesoporous structure of the synthesized materials. They contributed to Fenton reaction enhancement by generating effective reaction sites for potential adsorption and subsequent oxidative degradation of the azo dye. Based on these results, all clay supported nanomaterials have proved to be superior heterogeneous Fenton-like catalysts for removing azo dyes from wastewater.

Characterization of the binding of chrysoidine, an illegal food additive to bovine serum albumin

Chrysoidine is an industrial azo dye and the presence of chrysoidine in water and food has become an environmental concern due to its negative effects on human beings. Binding of dyes to serum albumins significantly influence their absorption, distribution, metabolism, and excretion properties. In this work, the interactions of chrysoidine with bovine serum albumin (BSA) were explored. Isothermal titration calorimetry results reveal the binding stoichiometry of chrysoidine to BSA is 1:15.5, and van der Waals and hydrogen bonding interactions are the major driving force in the binding of chrysoidine to BSA. Molecular docking simulations show that chrysoidine binds to BSA at a cavity close to Sudlow site I in domain IIA. However, no detectable conformational change of BSA occurs in the presence of chrysoidine as revealed by UV–vis absorption, circular dichroism and fluorescence spectroscopy studies.

Decolorization of organic dye (NBB) using Fe(III)P2W12Mo5/H2O2 system

ABSTRACT This study evaluates the potential of Fe(III)P2W12Mo5/H2O2 system in the decolorization of one common industrial azo dye, naphthol blue black (NBB). The effects of different parameter’s dye decolorization were investigated. The studied parameters were: the initial pH, the initial H2O2 concentration, the catalyst mass, and the initial dye concentration. The optimal conditions for a maximum discoloration efficiency (100%) are: pH: 3, [NBB]0 = 10 mg/L, Catalyst mass : 0.3 g, [H2O2]0 = : 2 m M. The spectrophotometric analysis indicated that the decolorization of the azo dye with Fe(III)P2W12Mo5/H2O2 was due to the reduction of the azo bonds. This study verifies the viability of the use of Fe(III)P2W12Mo5/H2O2 in the decolorization of NBB.

Binding of chrysoidine to catalase: Spectroscopy, isothermal titration calorimetry and molecular docking studies

Chrysoidine is an industrial azo dye and the presence of chrysoidine in water and food has become an environmental concern due to its negative effects on human beings. In this work, the interactions between chrysoidine and bovine liver catalase (BLC) were explored. Obvious loss in catalytic activity was observed after incubation of BLC with chrysoidine, and the inhibition effect of BLC was found to be of the non-competitive type. No profound conformational change of BLC occurs in the presence of chrysoidine as revealed by UV–vis absorption, circular dichroism and fluorescence spectroscopy studies. Isothermal titration calorimetry results indicate that catalase has two sets of binding sites for chrysoidine. Further, molecular docking simulations show that chrysoidine is located within the bottleneck in the main channel of the substrate to the active site of BLC, which explain the activity inhibition of BLC by chrysoidine.

Degradation of industrial azo dye in aqueous solution by heterogeneous Fenton process (fly ash/H2O2)

The aim of this study was to investigate the possibilities and efficiency of heterogeneous Fenton process with the use of fly ash from thermal power plants Kolubara, Serbia, as the catalyst in the degradation of industrial azo dye Zetanyl Rosso B-NG. The effects of various experimental parameters such as pH, temperature, concentration of fly ash, the initial concentration of H2O2 and initial concentration of dye on the kinetics and efficiency of decolorization were investigated. Simultaneous leaching of iron from fly ash was monitored. The optimum conditions had been determined, and it was found that decolorization efficiency obtained after 150 min of reaction, was about 98.9%. The optimal parameters were: initial pH = 3; [H2O2]0 = 6 mM; dosage of fly ash = 0.1g/l (for dye concentration of 100 mg/l); temperature = 22 ?C. The effectiveness of the applied treatment for mineralization of dye solution was investigated, under optimal conditions determined by the examination of various factors influencing the decolorization process at the specified contact time. The maximum achieved reduction of total organic carbon content was 96.5%. The results indicate that the reuse of fly ash as the catalyst support in ?OH production in this process achieves significant efficiency in terms of decolorization, 94.4% and mineralization, 89.6%. Futhermore, fly ash showed adequate stability during the reaction (low iron leaching, concentrations under optimal reaction condition were about 2 mg/l).

Decolorization of industrial azo dye in an anoxic reactor by PUF immobilized Pseudomonas oleovorans

This work reported the full degradation of an azo dye in a synthetic effluent by Pseudomonas oleovorans immobilized in polyurethane foam (PUF). For each fed-batch experiment, a screw-top vessel containing 160 mL of nutrient broth was inoculated with 0.16 g L−1 of fresh culture, incubated at 32 °C and supplemented with 50 mg L−1 of dye every 24 hours. Afterwards, the P. oleovorans were immobilized in PUF and inoculated in an anoxic reactor. The results showed that at fed-batch conditions, P. oleovorans was capable of removing 50 mg of dye in 192 hours. However, when the decolorization was performed in an anoxic reactor, it was capable of fully degrading 25 mg of dye in only 24 hours.

Decolorization of Naphthol Blue Black using the Horseradish Peroxidase

This study evaluates the potential of the enzyme horseradish peroxidase in the decolorization of one common industrial azo dye, naphthol blue black. Studies are carried out to understand the process parameters such as pH, temperature and reaction time. The enzymatic decolorization of the dye was examined by UV-Vis spectrophotometer and LC-MS measurements. Temperature and pH conditions were optimized for obtaining high azo-dye decolorization. Azo-dye removal at a pH range 4-6 was found to be the highest for all temperatures. After 5 minutes of treatment, the color removal of dye was ca. 80-90%. The LC-MS and spectrophotometric analyses indicated that the decolorization of the azo dye with enzyme was due to the reduction of the azo bonds. This study verifies the viability of the use of the horseradish peroxidase in the decolorization of naphthol blue black.

Decolorization of different azo dyes by Phanerochaete chrysosporium RP78 under optimal condition

Detoxification of synthetic dyes is one of the main challenges in clearing textile industry wastes. Biodegradation of azo-dyes using Phanerochaete chrysosporium is one the most environmentally friendly methods available. The main enzymes responsible for mycodecolorization process are lignin and manganese peroxidases. Here, optimization of expression conditions has been carried out with manipulating culture condition and nutrient sources. Therefore, the effects of buffer and temperature as well as nitrogen source on lignin peroxidase and manganese peroxidase production were investigated at two levels and four levels, respectively. For this purpose, P. chrysosporium RP78 based on Taguchi design of experiment has been applied. Maximum lignin and manganese peroxidase activities of 182 ± 2.5 U/L and 850 ± 41 U/L were obtained under predicted optimum conditions, respectively. Thereby, about 100 % decolorization was achieved after 24 h for two most widely used groups of azo dyes in textile industry consisting reactive and acidic. The physical adsorption of the azo dyes by mycelia was not significant which indicated that the enzymatic degradation of the dyes was occurred. Time profile of these enzymes showed that manganese peroxidase was peaked on 9 th day while lignin peroxidase peaked on 13 th. day and remained stable in the culture. The extracellular expression profiles of both were studied by 2 dimensional gel electrophoresis to partially characterize the enzymes.

Decolourisation and degradation of textile dyes using a sulphate reducing bacteria (SRB) – biodigester microflora co-culture

Successful decolourisation and degradation of textile dyes was achieved in a biosulphidogenic batch reactor using biodigester sludge from a local municipality waste treatment plant as a source of carbon and microflora that augmented a sulphate reducing bacteria (SRB) consortium. Orange II (O II) was decolourised by 95% within one day (24 h) producing 1-amino-2-naphthol and stoichiometric quantities of sulphanilic acid. The latter was degraded steadily (from
290 to 43 iM) over 20 days while 1-amino-2-naphthol disappeared from the reactor within two days. Other azo dyes, Reactive black 5 (RB 5), Reactive red 120 (RR 120), Remazol Brilliant violet 5R (RBV 5R), an anthraquinone dye Reactive blue 2 (RB 2) and an industrial azo dye mixture (Da Gama Textiles, King Williams Town, South Africa) were successfully degraded with the exception of Amido black 10B (AB 10B). The Orange II degrading cultures were freeze dried to investigate the feasibility of commercialising a powdered mixed starter culture for textile effluent bioremediation, but this decreased the dye degrading efficiency. Therefore bioremediation of textile effluent with sludge and SRB can concomitantly treat two wastes while providing a cheaper alternative of the carbon source. However, the fate of more aromatic amines needs to be investigated before full commercialisation of the process.

Decolouration of industrial azo dyes by crude laccase from Trametes hirsuta

The decolouration of several azo dyes, commonly used in the leather industry, by crude laccase obtained from Trametes hirsuta cultivation was assessed. Among the six dyes studied four showed a decolouration percentage higher than 50% in 4 h, whereas the other two showed more resistance to degradation. These results show the ability of laccase towards different dye structures as well as its enormous potential for the decolouration of recalcitrant azo dyes.

In vitro degradation of a reactive azo dye by crude ligninolytic enzymes from nonimmersed liquid culture of Phanerochaete chrysosporium

In vitro degradation of synthetic dyes by ligninolytic enzymes from white rot fungi is one potential way to deal with dye pollution compared with decolorization by conventional biological treatment. In this work, production of the ligninolytic enzymes was carried out at C/N ratios of 28/44 mM and 56/2.2 mM in nonimmersed liquid culture of Phanerochaete chrysosporium. In vitro decolorization of one industrial azo dye, Reactive brilliant red K-2BP, by crude lignin peroxidase (LiP) and manganese peroxidase (MnP) obtained under carbon and nitrogen limitation respectively, was examined and compared for their degradation characteristics. Both decolorization by LiP and MnP were sensitive to pH, peaking around pH 3.0, and improved at higher enzyme activities. Decolorization by LiP can be enhanced to the greatest degree (89%) with higher addition of H 2O 2 and veratryl alcohol, whereas decolorization by MnP was optimized only with a suitable dose of H 2O 2 (0.1 mM) and decreased by the addition of Mn 2+. Decolorization declined at high dye concentrations; LiP was able to decolorize a dye concentration of 60 mg/l and below to no less than 85%, and MnP of 10 mg/l to a maximum of 71%. Decolorization by LiP and MnP together was somewhat lower than that by LiP alone. It is suggested that the optimization of the H 2O 2 supply was mainly responsible for a high efficiency in continuous dye degradation by crude LiP and MnP.

Dye decolorization by Trametes hirsuta immobilized into alginate beads

The present paper studies the production of laccase by Trametes hirsuta immobilized into alginate beads in an airlift bioreactor. In order to enhance laccase production fresh ammonium chloride was added, which led to the production, of high laccase activities (around 1000 U l−1). The bioreactor operated for 40 days without operational problems and the bioparticles maintained their shape throughout fermentation. Dye decolorization was performed at bioreactor scale operating in the batch mode. High decolorization percentages were obtained in a short time (96% for indigo carmine and 69% for phenol red in 24 h), indicating the suitability of this process for application to synthetic dye decolorization. On the other hand, in vitro decolorization of several industrial azo dyes by crude laccase produced in the above bioreactor was also performed. It was found that some of the dyes needed the addition of 1-hydroxybenzotriazole for their decolorization.

Laboratory Studies of Electrochemical Treatment of Industrial Azo Dye Effluent

Removal of color and reduction of chemical oxygen demand (COD) in an industrial azo dye effluent containing chiefly reactive dyes were investigated under single-pass conditions at a dimensionally stable anode (DSA) in a thin electrochemical flow reactor at different current densities, flow rates, and dilutions. With 50% diluted effluent, decolorization was achieved up to 85-99% at 10-40 mA/ cm2 at 5 mL/min flow rate and 50-88% at 30-40 mA/ cm2 at high (10-15 mL/min) flow rates. The COD reduction was maximum (81%) at 39.9 mA/cm2 or above when solution-electrode contact time (Ct) was as high as 21.7 s/cm2 and decreased as Ct declined at a given current density. Cyclic voltammetric studies suggesting an indirect oxidation of dye molecules over the anode surface were carried out at a glassy carbon electrode. The effect of pH on decolorization and COD reduction was determined. An electrochemical mechanism mediated by OCl- operating in the decolorization and COD reduction processes was suggested. The effluent was further treated with NaOCI. The oxidized products from the treated effluents were isolated and confirmed to be free from chlorine-substituted products by IR spectroscopy. From the apparent pseudo-first-order rate data, the second-order rate coefficients were evaluated to be 2.9 M(-1) s(-1) at 5 mL/ min, 76.2 M(-1) s(-1) at 10 mL/min, and 156.1 M(-1) s(-1) at 15 mL/ min for color removal, and 1.19 M(-1) s(-1) at 5 mL/min, 1.79 M(-1) s(-1) at 10 mL/min, and 3.57 M(-1) s(-1) at 15 mL/min for COD reduction. Field studies were also carried out with a pilot-scale cell at the source of effluent generation of different plants corresponding to the industry. Decolorization was achieved to about 94-99% with azo dye effluents at 0.7-1.0 L/min flow costing around Indian Rupees 0.02-0.04 per liter, and to about 54-75% in other related effluents at 0.3-1.0 L/min flow under single-pass conditions.

FS01.1 The use of azo dyes in the European Union – legislation review

The aim of this paper is to review the European legislation concerning the use of textile dyes.It is known that different dyes of different classes can be sensitizing and cause allergic contact dermatitis for both textile workers and consumers.The European Union has created restraining directives regarding the manufacture and distribution of potentially dangerous products, such as aromatic amines. A specific scientific committee of EU stated that the carcinogenic capacity of some azo dyes is related to chemical releasing of aromatic amines (groups MAK III; A1; A2).In this paper, focus will be centred on the latest European Union Directives in this matter and the prohibition of some azo dyes in textile industry.

Application of power ultrasound for azo dye degradation

Power ultrasound of 850 kHz at 60, 90 and 120 W was used for the degradation of industrial azo dyes Acid Orange 5 and 52, Direct Blue 71, Reactive Black 5 and Reactive Orange 16 and 107. The results show that power ultrasound is able to mineralize azo dyes to non-toxic end products, which was confirmed by respiratory inhibition test of Pseudomonas putida. All investigated dyes have been decolorized and degraded within 3–15 h at 90 W and within 1–4 h at 120 W, respectively. Mass spectrometric investigations show, that hydroxyl radicals attack azo dyes by simultaneous azo bond scission, oxidation of nitrogen atoms and hydroxylation of aromatic ring structures. A volumetric scale-up showed a correlation between the energy input and the absolute amount of degraded dye. Up to an energy input of about 90 W no enzymatic deactivation of laccase was observed which might be helpful for a simultaneous action of sonochemical and enzymatic treatments.

ADSORPTION CHROMATOGRAPHY OF DIRECT AZO DYES.

DIRECT azo dyes contain in most cases a number of coloured by-products which may adversely influence the shade of the dye, its stability in light and distort its biological action. In view of the importance of direct azo dyes in industry as well as in biology and medicine a number of authors1–10 worked on the problem of their purification. So far it has not been possible to separate these dyes completely (strong adsorption of dyes on cellulose in paper chromatography or electrophoresis, losses during crystallization, etc.). This communication describes a simple method of separation which excludes use of cellulose. Tests with agar electrophoresis, though there was some movement of dyes, did not lead to satisfactory separation. Therefore, I carried out adsorption chromatography on aluminium oxide. This method, though it has been frequently used for the separation of other dyes11–15, has not been used in practice for direct azo dyes.