Direct Azo Dye Research Articles

Adsorptive Removal of Direct Azo Dyes from Textile Wastewaters Using Weakly Basic Anion Exchange Resin

Direct dyes are still widely used for coloring a variety of materials due to their ease of use and the wide range of colors available at a moderate cost of production. In the aquatic environment, some direct dyes, especially the azo type and their biotransformation products, are toxic, carcinogenic and mutagenic. Hence the need for their careful removal from industrial effluents. It was proposed adsorptive retention of C.I. Direct Red 23 (DR23), C.I. Direct Orange 26 (DO26) and C.I. Direct Black 22 (DB22) from effluents using anion exchange resin of tertiary amine functionalities Amberlyst A21 (A21). Applying the Langmuir isotherm model, the monolayer capacities were calculated as 285.6 mg/g for DO26 and 271.1 mg/g for DO23. The Freundlich isotherm model seems to be the better one for the description of DB22 uptake by A21, and the isotherm constant was found to be 0.609 mg1-1/n L1/n/g. The kinetic parameters revealed that the pseudo-second-order model could be used for the description of experimental data rather than the pseudo-first-order model or intraparticle diffusion model. The dye adsorption decreased in the presence of anionic and non-ionic surfactants, while their uptake was enhanced in the presence of Na2SO4 and Na2CO3. Regeneration of the A21 resin was difficult; a slight increase in its efficiency was observed using 1M HCl, 1 M NaOH and 1 M NaCl solutions in 50% v/v methanol.

Removal Efficiency of Insoluble β-Cyclodextrin Polymer from Water-Soluble Carcinogenic Direct Azo Dyes.

A batch system was applied to study the adsorption of three dyes (methyl violet, eriochrom black T and helianthin) from aqueous solution onto β-cyclodextrin polymer, synthesized by using citric acid as a cross linking agent. This polymer lets to adsorb only methyl violet for this effect, several operator variables was checked only with this kind of dye, the removal efficiently increases with increase in adsorbent amount; elevation of temperature lets also to improve the dye adsorption; ionic strength has not effect on dye adsorption process, for the pH we have remarked a slight decrease in removal efficiently with increasing of pH values. Equilibrium study was investigated by applying three models (Langumir, Frendlich and Temkin), results show that Langumir isotherm is the appropriate model. FTIR spectra show the complex inclusion formation which dominates the adsorption mechanism, confirmed by the absence of characteristic peaks of methyl violet in ß-cyclodextrin after adsorption.

Chemoinformatics Analysis of the Colour Fastness Properties of Acid and Direct Dyes in Textile Coloration

The efficiency of chemoinformatics methods based on a fragment approach for the analysis of relationships between the chemical structure of textile dyes and colour fastness of the dyeings have been shown by examining a large set of properties, including the light fastness of acid dyes on wool and polyamide fibres, the sensitivity of acid dyes on wool to oxygen bleaching, the wash fastness of acid dyes on wool, the adsorption of direct dyes on cotton, and the photodegradation of azo dyes in solution. An analysis of the developed regression models depicted the contribution of ten substructural molecular fragments for each indicator of the colour fastness properties of acid and direct azo dyes on textile materials. The similarity of several individual multi-atomic fragments for acid and direct azo dyes was found for wool, polyamide, and cotton fibres, which indicates the coinciding mechanisms of the physicochemical processes that accompany the destruction of dyes while testing the light fastness and sensitivity of the dyeings to oxygen bleaching, as well as their adsorption/desorption with the wash fastness and dyeability of wool and cotton.

Wasteful Azo Dyes as a Source of Biologically Active Building Blocks.

In this work, an environment-friendly enzymatic strategy was developed for the valorisation of dye-containing wastewaters. We set up biocatalytic processes for the conversion of azo dyes representative of the main classes used in the textile industry into valuable aromatic compounds: aromatic amines, phenoxazinones, phenazines, and naphthoquinones. First, purified preparations of PpAzoR azoreductase efficiently reduced mordant, acid, reactive, and direct azo dyes into aromatic amines, and CotA-laccase oxidised these compounds into phenazines, phenoxazinones, and naphthoquinones. Second, whole cells containing the overproduced enzymes were utilised in the two-step enzymatic conversion of the model mordant black 9 dye into sodium 2-amino-3-oxo-3H-phenoxazine-8-sulphonate, allowing to overcome the drawbacks associated with the use of expensive purified enzymes, co-factors, or exquisite reaction conditions. Third, cells immobilised in sodium alginate allowed recycling the biocatalysts and achieving very good to excellent final phenoxazine product yields (up to 80%) in water and with less impurities in the final reaction mixtures. Finally, one-pot systems using recycled immobilised cells co-producing both enzymes resulted in the highest phenoxazinone yields (90%) through the sequential use of static and stirring conditions, controlling the oxygenation of reaction mixtures and the successive activity of azoreductase (anaerobic) and laccase (aerobic).

A comprehensive investigation of dye–chitosan blended films for green chemistry applications

ABSTRACTIn this paper, the ability of chitosan film to remove dyestuff from wastewater was evaluated for environmental applications, using three commercial direct azo dyes. Two chitosan films were adopted: the standard one prepared following a well‐known procedure to form it, and a novel one, with a weakly acidic character. Moreover, to improve the adsorption process, the hydrophobic character of the films was investigated. The pH of the dye solutions was also changed, showing an excellent ability in dye removal at pH 12. The films were characterized by means of spectroscopic and morphologic methods to better understand the nature of interactions between dyes and chitosan chains. Swelling ratio measurements were also performed. All analyses suggest that all dyes showed a strong affinity to chitosan polymer chains, with the presence of extended hydrogen bonds and Van der Waals forces perturbing the chitosan network. Interestingly, very good results were obtained in recycling experiments related to the dyeing capacities of chitosan blended films in the presence of textiles. An ecofriendly application is thus presented in this paper. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45945.

Effective degradation of primary color direct azo dyes using Fe0 aggregates-activated persulfate process

The present study examined the oxidation power of a Fe0 aggregates/persulfate (PS/Fe0) system for the degradation of the wastewater containing mixed primary direct dyes (i.e., Sirius® Gelb S-2G, Sirius® Red F3B, and Sirius® Turkis GL01). Results indicated that decolorization efficiency was determined by operating parameters of the PS/Fe0 system and the structural complexity of dye molecules. System efficiency increased with increasing persulfate and Fe0 dosages. Faster decolorization was observed in experiments conducted at pH < 10. The process obeyed a first-order kinetics. Slow heterogeneous reactions were observed at high initial pH (>10.5) and low PS concentration (<2 × 10−3 M). Inhibitory effect occurred in systems containing salts Na2SO4, NaCl, Na2CO3, and Na2HPO4 at 1 × 10−2 M. The effect was suppressed when reaction temperature was raised to 55 °C. Heat enhanced not only decolorization efficiency, but also COD removal. Complete decolorization of a mixed dye containing ADMI (the American Dye Manufacture Institute) 15105 was achieved within10 min in the PS/Fe0/55 °C system with an initial pH of 6.0 and dosages of 5 × 10−3 M Na2S2O8 and 0.5 g/L Fe0. Low molecular weight intermediates including organic acids were identified. Due to a relatively low activation energy (4.68 kcaL/mol), the PS/Fe0 system exhibited higher efficiency at higher temperature. This study demonstrated that Fe0-activated PS is a promising process for the treatment of textile wastewaters containing mixed azo direct dyes.

Ultrasound and UV Stimulated Heterogeneous Catalytic Oxidation of an Azo Dye: A Synergistic Effect

This research deals with the decolourisation of direct azo dye, Direct Blue 71 (DB71), in aqueous solution by means of sonocatalytic, photocatalytic and sonophotocatalytic heterogeneous oxidation processes in the presence of a zinc oxide (ZnO) catalyst. The effect of these oxidation processes under visible light and 20 kHz ultrasound was investigated to study their influence on degradation rates by varying the initial dye concentration, pH and catalyst load and to understand the effect of synergy on the degradation process. The synergistic effect is quantified in terms of a synergy factor which has already been defined in the literature. The highest value of the factor was obtained for a low DB71 dye concentration at pH 5.5, 20 °C temperature and 400 mg L−1 optimum ZnO dosage. Pseudo first-order kinetics were followed for the removal of the azo dye according to the Langmuir–Hinshelwood model. For comparison, the Langmuir–Hinshelwood model was also used for experimental values obtained from the sonocatalytic process, the photocatalytic process and the combination of these processes. The Langmuir–Hinshelwood kinetic model demonstrated consistency in all calculations of the initial rates of degradation with the appropriate values for the reaction rate constant and DB71 dye absorption constant.

Tourmaline activated persulfate for degradation of Sirius Türkis GL 01

The high Fe2+ content of tourmaline (TM) has potential of activating a persulfate reaction. However, information pertaining to using TM as an activator in persulfate oxidation process is currently unavailable. In this study, powdered TM was used to activate persulfate (PS) oxidation for decolorization synthetic direct azo dye, Sirius Turkis GL 01 (STGL). Findings revealed that decolorization was significantly enhanced by TM/PS combined with ultrasound. A suitable oxidation condition for removal true color was TM 1.5 g/L, PS 5 × 10−4 M, US 106 W/cm2 (20 min sonication at 20 kHz), and initial pH 6.0, which could completely remove the color and COD of 40 mg/L STGL after 20 min treatment. Oxidation condition under higher TM dosage with higher sonication power is beneficial for generation of sulfate radicals, consequently, promoting the oxidation performance of TM/PS process. Results clearly indicated that Fe-tourmaline, can be potentially used to activate PS oxidation for effective decolorization of wastewater containing direct azo dyes.

Ultrasound and heat enhanced persulfate oxidation activated with Fe0 aggregate for the decolorization of C.I. Direct Red 23

Effluents from the paper printing and textile industries are often heavily contaminated with azo dyes. Azo dyes are difficult to oxidize biologically. This work investigated the decolorization of an azo dye, C.I. Direct Red 23 (DR23), by persulfate (PS) activated with Fe0 aggregates (PS/Fe0). Ultrasound (US) and heat were used as enhancement tools in the PS oxidation system. Neither US-activated PS nor thermally activated PS was effective in oxidizing DR23. However, the decolorization was significantly enhanced by PS/Fe0 combined with US (PS/Fe0/US) or heat (PS/Fe0/55°C). Approximately 95% decolorization of 1×10−4M DR23 was achieved within 15min in the PS/Fe0/US system at an initial pH of 6.0, PS of 5×10−3M, Fe0 of 0.5g/L and US irradiation of 106W/cm2 (60kHz). Complete decolorization was achieved within 10min in the Fe0/PS/55°C system. The rate of decolorization doubled when US was introduced in the PS/Fe0 system during the treatment of different initial dye concentrations. The dependence of dye and true color (ADMI) depletion on PS concentration has been discussed. DR23 was completely degraded based on the disappearance of aromatic groups of UV–vis spectra and the variation of TOC mineralization. The observed pseudo-first-order decolorization rate was substantially enhanced by increasing temperature. The Arrhenius activation energy for the PS activated with Fe0 was estimated as 8.98kcal/mol, implying that higher temperature is beneficial for the DR23 decolorization. The addition of US into the PS/Fe0 system did not incur a substantial increase in electricity, whereas the mineralization of DR23 occurred quickly. Thus, both PS/Fe0/US and heated PS/Fe0 systems are practically feasible for the effective degradation of the direct azo dye in textile wastewater.

Carcinogenic direct azo dye removal from aqueous solution by amino-functionalized calix[4]arenes

This study contains a convenient synthesis and azo dye extraction efficiency of amino-functionalized calix[4]arene derivatives. Two calix[4]arene derivatives bearing alkyl amino groups on their upper and lower rim have been successfully synthesized and used as extractant for dye removal in liquid–liquid extraction system. The effect of electrolyte concentration, contact time, and pH on azo dye extraction was also investigated for all calixarene derivatives. From the results, it has been deduced that the amino-functionalized calix[4]arenes showed a better affinity than other parent calix[4]arenes towards the selected azo dyes.

Enzymatic degradation of azo dyes using three macrophyte species: Arundo donax, Typha angustifolia and Phragmites australis

The aim of this study was to investigate the potential role of three macrophyte species (Arundo donax, Typha angustifolia and Phragmites australis) for degradation of azo dyes. Activities of peroxidases enzymes involved in plant protection against stress were tested for dye decolourization. In order to conduct the enzyme activity assay, the fresh extract was obtained from crude extracts of leaves. The oxidation capability of peroxidase (POD) on direct azo dyes (amaranth and amido black) was investigated and found to be an effective treatment methodology. The performance of peroxidase was evaluated in soluble and free form in the presence of H2O2. The oxidation was tested as a function of peroxidase at constant POD activity. Parameters such as temperature (5–70°C), concentration of H2O2 (0–1000 μM/L), pH (4–10), dye concentration (0.002–1 mM/L) and enzyme amount (5–20 μL) were studied. Results show that P. australis, leaves contained the highest peroxidase activity. The dye decolourization is about 87% for amido black and 93% for amaranth after 120 h of reaction time. The bio removal efficiency depends on the reaction time, initial dye and enzyme concentrations, pH and temperature.

Degradation of direct azo dye by Cucurbita pepo free and immobilized peroxidase

Enzymatic decolourization of the azo dye, Direct Yellow (DY106) by Cucurbita pepo (courgette) peroxidase (CP) is a complex process, which is greatly affected by pH, temperature, enzyme activity and the concentrations of H2O2 and dye. Courgette peroxidase was extracted and its performance was evaluated by using the free-CP (FCP) and immobilized-CP (ICP) forms in the decolourization of DY106. Immobilization of peroxidase in calcium alginate beads was performed according to a strategy aiming to minimize enzyme leakage and keep its activity at a maximum value by optimizing sodium alginate content, enzyme loading and calcium chloride concentration. The initial conditions at which the highest DY106 decolourization yield was obtained were found at pH 2, temperature 20°C, H2O2 dose 1 mmol/L (FCP) and 100 mmol/L (ICP). The highest decolourization rates were obtained for dye concentrations 50 mg/L (FCP) and 80 mg/L (ICP). Under optimal conditions, the FCP was able to decolorize more than 87% of the dye within 2 min. While with ICP, the decolourization yield was 75% within 15 min. The decolourization and removal of DY106 was proved by UV-Vis analysis. Fourier transform infrared (FT-IR) spectroscopy analysis was also performed on DY106 and enzymatic treatment precipitated byproduct.

Decolourization of direct blue 15 by Fenton/ultrasonic process using a zero-valent iron aggregate catalyst

Decolourization of direct azo dye, direct blue 15 (DB15), by an advanced Fenton process coupled with ultrasonic irradiation (Fenton/US) was investigated. Zero-valent iron (ZVI) aggregates were used as the catalyst. A positive synergistic effect occurred when Fenton’s reagent was combined with ultrasonic irradiation. Experimental results showed that the optimum conditions for decolourization were pH 3.0, Fe(0) 1g/L, H2O2 5.15×10−3mol/L with ultrasound density of 120W/L at 60kHz. These conditions yielded 99% decolouration of 4.7×10−5 M DB15 (4130 ADMI) solution within 10min. DB15 decolouration follows the first-order decolouration kinetics. Although the solutions containing H2CO3, Cl−, ClO4-, NO3- and SO42- ions did not have a significant effect on the decolouration, the H2PO4- ion did decrease the decolouration rate. High ultrasonic input power accelerated the reaction and increased decolourization efficiency. The cost effectiveness of this process at high ultrasound density could be controlled despite the high electricity costs incurred by the process. ZVI aggregates were reusable; however, an increase in the number of times ZVI was recycled decreased the decolourization rate. This study demonstrates that a Fenton/US process can effectively decolour the direct azo dye DB15 in wastewater.

SYNTHESIS, COLORFASTNESS EVALUATION AND UTILIZATION OF HUMIC ACID DERIVED DYES / PIGMENT

ABSTRACT Pakistan coal derived humic acid (HAL) salt was used to synthesize direct azo and acid dyes by coupling reaction with arylamines and its substituted derivatives (R 1 -R 15 ) for dyeing industry as a reaction intermediates. A variety of color shades ranging from light to deep brown and yellowish were obtained by applying the dyes (D 1 -D 15 ) to various fabrics. The dyes were noteworthy due to bio-organic in nature, excellent colorfastness to perspiration and washing. The presence of chromophoric groups in a humic acid will explore the utilization of such a natural polymer as potential candidate for the synthesis of dyes and pigments. Colorfastness tests had been studied and significant performance was observed for pure cotton, silk and wool fabrics with certain limitations. The dyed fabrics showed fair to good colorfastness to light and very good to excellent fastness to washing, perspiration, rubbing and seawater. Humic acid and its calcium salt were used to prepare anti-rust pigment using indigenous technique. The humic pigment (HAP) was successfully used for anti-rust purposes in marine paint composition and textile printing application for polyester-cotton fabric. The colorfastness features of printed fabrics were evaluated in comparison with commercially available carbon black pigment (CBP). The computational color data (CIELab) analysis for dyed and printed fabrics were exhibited a good performance of humic derivatives as UV-absorber for value added textile.

Removal of direct azo dyes and aromatic amines from aqueous solutions using two β-cyclodextrin-based polymers

Two β-cyclodextrin (β-CD)-based polymers were synthesized using 4,4′-methylene-bis-phenyldiisocyanate (MDI) or hexamethylenediisocyanate (HMDI) as a cross linking agent in dimethylformamide and used as sorbents for the removal of azo dyes (Evans Blue and Chicago Sky Blue), as well as aromatic amines (benzidine, p-chloroaniline and α-naphthalamine) from aqueous solutions. The sorption experiments were carried out by using batch-wise procedure involving the determination of pH effect, sorbate concentration and contact time. Moreover, from the equation isotherms such as Langmuir and Freundlich were successfully applied to model the experimental data. From the results polymer 2 was found to be a better sorbent for both azo dyes and the aromatic amines as compared to polymer 1 as proved by Langmuir isotherm model. The proposed sorption mechanism involved several kinds of interactions: physical adsorption, hydrogen bonding and formation of an inclusion complex due to the β-CD molecules through host–guest interactions.

Adsorption of Congo Red dye on hazelnut shells and degradation with Phanerochaete chrysosporium

The present work concerns the experimental evaluation of hazelnut shells as a low cost natural biosorbent. Adsorption of the direct azo dye Congo Red was performed within a concentrations range of 50-5000 mg/L. Hazelnut shells were employed as organic support for Phanerochaete chrysosporium cultures to study the best cultural medium composition for the MnP production. The capability of Phanerochaete chrysosporium to take macronutrients as carbon and nitrogen from hazelnut shells was demonstrated. Cultures of Phanerochaete chrysosporium were carried out with hazelnut shells coming from Congo Red adsorption tests, showing that 43% of the adsorbed dye was degraded.

Removal efficiency of a calix[4]arene-based polymer for water-soluble carcinogenic direct azo dyes and aromatic amines

A Mannich base derivative of 5,11,17,23-tetrakis-[(1,4-dioxa-8-azaspiro-[4.5]decanyl)methyl]-25,26,27,28-tetrahydroxy calix[4]arene 3 was synthesized by the treatment of calix[4]arene with a cyclic secondary amine (1,4-dioxa-8-azaspiro-[4.5]decane) and formaldehyde. The compound 3 was treated with dibromoxylene to obtain a calix[4]arene-based copolymer 4. In batch sorption experiments of selected carcinogenic azo dyes and aromatic amines, the compounds 3 and 4 were found to be a better sorbent for azo dyes than for the aromatic amines. It was observed that the percentage of azo dye removal was 95–99% for compound 3 and 83–97% for 4 when the pH of the dye solution was in the range of 2.0–8.0. The sorption of azo dyes and aromatic amines by calix[4]arenes-based compounds indicates that amino groups play the major role for the formation of hydrogen bonds and electrostatic interactions.

Removal of Carcinogenic Direct Azo Dyes from Aqueous Solutions Using Calix[n]arene Derivatives

AbstractCalix[n]arenes having different internal cavities sizes were synthesized. The ability of these sorbents to extract carcinogenic direct azo dyes from water by a solid‐liquid extraction process was studied and compared to results obtained with the unsubstituted calix[n]arene. The carboxylic acid derivative of calix[6,8]arene showed the highest affinity towards the azo dyes. The sorption capacity of dyes on the calix[n]arenes was dependent on the presence of sulfonate groups on the anionic dyes. The optimum pH value for dye sorption was observed at pH 3.5 to 8.5 for all calixarene derivatives. The proposed sorption mechanism involves several kinds of interactions: electrostatic repulsion between carboxylic acid groups of calix[n]arenes and sulfonate groups of azo dyes, hydrogen bonding and formation of an inclusion complex through host‐guest interactions.

Biosorption of direct azo dye from aqueous phase onto Spirogyra sp. I02: Evaluation of kinetics and mechanistic aspects

Sorption of azo dye from aqueous phase was evaluated using non-viable algal Spirogyra I02 as biosorbent. Agitated non-flow batch sorption studies revealed the capacity of algal biosorbent to adsorb the azo dye. Influence of dye concentration, effect of pH, biosorbent dosage, temperature effect and sorption–desorption were studied to evaluate the algal-dye sorption mechanism. Sorption interaction of dye on to algal species obeyed the pseudo second-order rate equation. Experimental data showed good fit with the Langmuir's adsorption isotherm model. Dye sorption was found to be dependent on the aqueous phase pH and the uptake was observed to be higher at lower pH. Maximum dye sorption was observed at 30 °C temperature. Sorption–desorption of dye into organic and/or inorganic solutions were observed and this indicated the combined effect of chemical and ion-exchange sorption phenomena.

Degradation of azo dyes by Trametes villosa laccase over long periods of oxidative conditions.

Trametes villosa laccase was used for direct azo dye degradation, and the reaction products that accumulated after 72 h of incubation were analyzed. Liquid chromatography-mass spectrometry (LC-MS) analysis showed the formation of phenolic compounds during the dye oxidation process as well as a large amount of polymerized products that retain azo group integrity. The amino-phenol reactions were also investigated by 13C-nuclear magnetic resonance and LC-MS analysis, and the polymerization character of laccase was shown. This study highlights the fact that laccases polymerize the reaction products obtained during long-term batch decolorization processes with azo dyes. These polymerized products provide unacceptable color levels in effluents, limiting the application of laccases as bioremediation agents.