Textile Azo Dyes Research Articles

Exploring docking and aerobic-microaerophilic biodegradation of textile azo dye by bacterial systems

Aeromonas hydrophila MTCC 1739 and Lysinibacillus sphaericus MTCC 9523 non-adapted bacteria were investigated for decolorization of 100 mg L−1 of a textile azo dye Drimaren Red CL-5B in Nutrient Broth at 37 °C, pH 8 under sequential aerobic-microaerophilic conditions for 72 h. Docking by Biosolve IT software was used to calculate docking score, identify active site residues and molecular interactions between laccase and azoreductase of both bacteria with dye. Docking score and decolorization percentage were assessed comparatively. UV–vis spectroscopy, HPLC, FTIR and GC–MS were performed for biodegradation analysis. Laccase, veratryl alcohol oxidase and azoreductase enzymes were assayed. Docking score of −31.9921, −18.1289 and −27.2792, −2.5185 kJ/mol for laccase and azoreductase while 91.96 and 88.35 % decolorization were achieved by A. hydrophila MTCC 1739 and L. sphaericus MTCC 9523 respectively. Docking studies analyzing interactions between dye and dye-degrading enzymes were in agreement with decolorization percentage. Biodegradation analysis supported biotransformation of dye into simpler products. Enzyme studies revealed high expression of dye degrading enzymes in both non-acclimatized bacteria on exposure to azo dyes compared to controls. It was suggested that A. hydrophila MTCC 1739 and L. sphaericus MTCC 9523 can be used for efficient decolorization and biodegradation of azo dye containing textile wastewater. Thus, an advanced approach consisting of an in silico preliminary screening and subsequent bacterial dye degradation is validated for an ecofriendly, economical and time-efficient bioremediation to reuse treated water.

Biodegradation and Detoxification Efficiency of Azo-Dye Reactive Orange 16 by Pichia kudriavzevii CR-Y103

In consideration of the hazards associated with the presence of the textile azo-dye and their biotransformation products in the environment, the goal of this work was to study bioremediation process by the yeast strain Pichia kudriavzevii CR-Y103 related to the ability to degrade and detoxify the sulfonated Reactive Orange 16 azo-dye. In experimental conditions, the optimal inoculum/dye concentration ratio required for complete decolorization (100%) of culture medium and biomass within 24 h has been 1 g L−1 yeast cell (dry weight)/50 mg L−1 Reactive Orange 16. In the presence of 400 mg L−1 of Reactive Orange 16 (RO16), 95% of the dye was removed after 72 h of incubation. Also, the yeast strain could decolorize other eight textile dyes (56.48–99.98% decolorization within 24 h). NADH-DCIP reductase and azo reductase activities were significantly increased (ca. 5.4 times and ca. 37 times, respectively) during the decolorization process. UV-VIS spectra, high-performance liquid chromatography (HPLC), and Fourier transform infrared spectroscopy (FTIR) analysis confirmed the presence of new biotransformation products in extracted metabolites, highlighting the partial biodegradation of the dye by the new yeast isolate. The phytotoxicity evaluation strongly supported the decreased toxicity of biodegraded products as minor inhibition on germination (%), root and shoots elongation of T. pratense L. and T. aestivum L. seedlings. Increasing of mitotic index value and decreasing the frequency of chromosomal aberrations in tested plant meristem cells treated with biodegraded products, compared with RO16 treatment (500 ppm), confirmed their slightly toxic nature. A cell viability assay also confirmed the reduced toxicity of biodegraded products on healthy monkey kidney cells (Vero cells).

Treatment of artificial wastewater containing two azo textile dyes by vertical-flow constructed wetlands

The release of untreated dye textile wastewater into receiving streams is unacceptable not only for aesthetic reasons and its negative impacts on aquatic life but also because numerous dyes are toxic and carcinogenic to humans. Strategies, as of now, used for treating textile wastewaters have technical and economical restrictions. The greater part of the physico-chemical methods, which are used to treat this kind of wastewater, are costly, produce large amounts of sludge and are wasteful concerning some soluble dyes. In contrast, biological treatments such as constructed wetlands are cheaper than the traditional methods, environmental friendly and do not produce large amounts of sludge. Synthetic wastewater containing Acid Blue 113 (AB113) and Basic Red 46 (BR46) has been added to laboratory-scale vertical-flow construction wetland systems, which have been planted with Phragmites australis (Cav.) Trin. ex Steud. (common reed). The concentrations 7 and 208 mg/l were applied for each dye at the hydraulic contact times of 48 and 96 h. Concerning the low concentrations of BR46 and AB113, the unplanted wetlands are associated with significant (ρ < 0.05) reduction performances, if compared with planted wetlands concerning the removal of dyes. For the high concentrations of AB113, BR46 and a mixture of both of them, wetlands with long contact times were significantly (ρ < 0.05) better than wetlands that had short contact times in terms of dye, colour and chemical oxygen demand reductions. Regarding nitrate nitrogen (NO3-N), the reduction percentage rates of AB113, BR46 and a mixture dye of both of them were between 85 and 100%. For low and high inflow dye concentrations, best removals were generally recorded for spring and summer, respectively.

Decolorization of textile dyes by combination of gold nanocatalysts obtained from Acinetobacter sp. SW30 andNaBH4

Abstract In the present work, a new strategy for decolorization of textile dyes such as direct black 22 (DB) and reactive yellow 186 (RY) has been studied using sodium borohydride 100 mM ( NaBH 4 ) as a reducing agent and 6 . 5 μ g ∕ ml bacteriogenic gold nanoparticles (AuNP) as nanocatalysts. The combination of two could decolorize 93 and 83% of DB and RY in 20 and 30 min respectively. The rate constant for both the dyes were very less, indicating the higher affinity of AuNP for dyes. FTIR, HPLC and GC–MS confirm that NaBH4 reduces the dye at azo bond leading to decolorization of dyes. Phytotoxic and cytotoxic studies were performed on bulbs of Allium cepa which revealed the non-toxic nature of degraded metabolites towards onion bulbs. AuNP can be immobilized in sodium alginate beads and can be reused for 3 times with same efficiency of decolorization. This is the first report on the decolorization of textile azo dyes using AuNP as catalysts.

Batch and dynamic adsorption of Eriochrome Black T from water on magnetic graphene oxide: Experimental and theoretical studies

In this study we have synthesized a high surface area magnetic graphene oxide (MGO) impregnated with α-Fe2O3 for the removal of a toxic textile azodye Eriochrome Black T (EBT). MGO was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-rays (EDAX), fourier transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman, Superconducting quantum interference device (SQUID) and Brunauer-Emmet-Teller (BET) surface area analyzer. Batch adsorption of EBT with MGO was studied using various isotherms and it was found to follow Langmuir monolayer adsorption with 210.53 mg g−1 maximum adsorption capacity. Thermodynamic study indicates the adsorption to be spontaneous and exothermic in nature. The time-dependent adsorption followed pseudosecond order kinetics and intraparticle diffusion model indicates strong initial adsorption and the diffusion is controlled by both boundary layer and intraparticle diffusion. Attempt was made to study the dynamic EBT adsorption, for which a customized filter was prepared. It was observed that MGO has high adsorption capacity in this case as well which led to the conclusion that MGO filters have a great potential to be used commercially, becoming a futuristic adsorbent.

Bioremediation Efficiency of Heavy Metals and Azo Dyes by Individual or Consortium Bacterial Species Either as Free orImmobilized Cells: A Comparative Study

THE OBJECTIVE of the present study was to compare between free and immbolized bacterial cultuer/s in bioremediation of heavy metals and dyes to reduce environmental pollutants with the help of biological entities. The bacterial consortium consisting of Sphingomonas paucimobilis, Rhizobium radiobacter, and Bacillus subtilis was developed due to capabilities of the three bacterial species to remove heavy metals from industrial waste water and decolorize methyl orange and Congo red textile azo dyes than their corresponding single cultures. The immobilization of bacterial consortium on Ca-alginate increased its heavy metals removal efficiency more than 10% compared to consortium of free cells after 4 days. Also, decolorization ability of immobilized consortium was conducted for shorter time and higher concentrations of dyes than that of free one. The greater efficiency of immobilized consortium than free single culture may be correlated to synergistic activity of different metabolites of bacterial cultures and protection of cells from toxic pollutants that provided by Ca-alginate matrices which promoting an efficient bio-treatment of industrial effluents containing dyes and heavy metals.

Recycling food waste to clean water: the use of a biodigester's residual liquid inoculum (RLI) to decolourise textile azo dyes.

A residual liquid inoculum (RLI) was used to decolourise solutions of Acid Yellow 25 (AY25) and Direct Violet 51 (DV51) azo dyes. The RLI was obtained through anaerobic digestion of food waste from a university restaurant. The concentration of bacteria in the RLI was 8.45 × 107 CFU mL-1. Dye solutions (50 μg mL-1) were inoculated with the RLI (20% v/v) and incubated at room temperature. The decolourisation studies took place at microaerophilic and in-batch conditions and at pH = 2.50. Initially, the dyes were taken up from solution by biosorption; maximum colour removal was achieved after 3 hours of incubation, with 88.66% for AY25 and 77.65% of DV51. At prolonged incubation times (3-96 hours) decolourisation was mainly attributed to biodegradation of the azo solutions, with breakage of the azo bond, as detected by UV-VIS spectroscopy and Fourier transform infrared (FT-IR) analysis. Analysis of UV-VIS absorption rates of dyes showed, however, that AY25 was more readily biodegradable whereas DV51 was more recalcitrant to the action of the RLI.

Role of Azoreductases in Bacterial Decolorization of Azo Dyes

Azo dyes are largest class of synthetic dyes used in textile industries. The disposal of wastewater from textile industry may have serious environmental concern. Bacterial decolorization of azo dyes from textile wastewater is an environment friendly and cost effective treatment system. Various species of bacteria produces azoreductase enzyme which have shown great potential to decolorize the textile azo dyes via reductive cleavage of azo bond under anaerobic or aerobic conditions.

Functional group influences on the reactive azo dye decolorization performance by electrochemical oxidation and electro-Fenton technologies.

Electrochemical water treatment technologies are highly promising to achieve complete decolorization of dyebath effluents, as demonstrated by several studies reported in the literature. However, these works are focused on the treatment of one model pollutant and generalize the performances of the processes which are not transposable since they depend on the pollutant treated. Thus, in the present study, we evaluate, for the first time, the influence of different functional groups that modify the dye structure on the electrochemical process decolorization performance. The textile azo dyes Reactive Orange 16, Reactive Violet 4, Reactive Red 228, and Reactive Black 5 have been selected because they present the same molecular basis structure with different functional groups. The results demonstrate that the functional groups that reduce the nucleophilicity of the pollutant hinder the electrophilic attack of electrogenerated hydroxyl radical. Thereby, the overall decolorization efficiency is consequently reduced as well as the decolorization rate. Moreover, the presence of an additional chromophore azo bond in the molecule enhances the recalcitrant character of the azo dyes as pollutants. The formation of a larger and more stable conjugated π system increases the activation energy required for the electrophyilic attack of •OH, affecting the performance of electrochemical technologies on effluent decolorization.

Nitrogen and Carbon Sources Influencing Mycoremediation of Textile Dyes Using Novel Autochthonous Fungal Isolates

Four fungal isolates Trichoderma virens, Phlebiopsis cf. ravenelii, Talaromyces stipitatus, Aspergillus niger originally isolated from the textile dye contaminated soil of Meerut, India. They were studies for decolorization purpose of selected textile azo dyes under laboratory conditions. Out of total 74 isolates, four fungal strains were picked up on the basis of primary screening carried out using agar layer decolorization technique. Dye decolorization and degradation activity of the culture was enhanced by optimization of concentration of carbon and nitrogen sources to the synthetic medium. This optimization facilitated decolorization and degradation within 9 d, at pH 5.4 and at a temperature of 30°C. Different concentrations of tested dyes (0.01%, 0.025%, 0.05 and 0.1%) were used and maximum decolorization 99.84% was achieved at dye concentration of 0.01%. Rate of decolorization carried out at different concentrations revealed the increase in dye solution concentration suppresses the decolorization. Optimized amount of nutrients were found to be 0.05%, 0.2%, 0.5%, 1% and 2% of ammonium sulphate and sodium nitrate as nitrogen source and glucose and lactose as carbon source respectively. Addition of nitrogen source above 0.5% caused decrease in percentage decolorization and addition of carbon source increase percentage decolorization up to 0.5%.

In Silico Analysis of Bacterial Systems For Textile Azo Dye Decolorization and Affirmation With Wetlab Studies

A systemic approach involving in‐silico and in‐vitro tests were used for the decolorization of five azo dyes, Reactive Yellow F3R, Joyfix Yellow 53R, Remazol Red RR, Drimaren Black CL‐S and Disperse Red F3BS, using Aeromonas hydrophila SK16 and Lysinibacillus sphaericus SK13. Homology models for laccase and azoreductase enzymes from these two bacteria were generated using Accelrys Discovery Studio 3.5 and validated. Docking was performed with LeadIT software for binding energy calculation, and active site residues were identified. Reactive Yellow F3R showed highest binding energy with A. hydrophila, which emulated the decolorization percentage by ultraviolet–visible (UV–vis) spectroscopy. High‐performance LC (HPLC), Fourier transform IR spectroscopy (FTIR), and gas chromatography–mass spectrometry (GCMS) supported biotransformation and biodegradation of Reactive Yellow F3R by A. hydrophila SK16, and a biodegradation pathway was proposed. HPLC analysis of treated sample illustrated peaks at retention time 1.481, 3.165, 3.374, and 3.945 min while the control dye showed peaks at 1.478 and 3.106 min. GCMS analysis showed that (2Z)‐but‐2‐ene, 1,3,5‐triazine, aniline, and naphthalene were formed as end products. The in‐silico outcome was in good agreement with experimental studies. Thus, it can be surmised that in‐silico molecular modeling and docking studies can assist as a preliminary tool for screening of potential bacterial system to be employed in textile dye decolorization and degradation studies.

Biodecolorization of textile azo dye using Bacillus sp. strain CH12 isolated from alkaline lake

Textile azo dye decolorizing bacteria were isolated from alkaline Lakes Abaya and Chamo using Reactive Red 239 (RR239) dye. Through subsequent screening process, strain CH12 was selected to investigate the effects of nutrient supplement, DO, pH, temperature, dye concentration and types on decolorization. Based on 16S rRNA gene sequence analysis, strain CH12 was identified as Bacillus sp. Decolorization efficiencies were significantly enhanced with carbon (≥98%) and organic nitrogen (∼100%) supplements. Complete decolorization was also observed under anoxic and anaerobic conditions, and at the temperature of 30°C and the pH of 10. However, the azo dye decolorization efficiency of strain CH12 was significantly reduced when NaNO3 (1–8%) was supplemented or under aerobic culturing condition (≤6%), indicating that RR239 was less preferred electron acceptor. Overall, strain CH12 can be a promising candidate for decolorization applications due to its potential to effectively decolorize higher RR239 concentrations (50−250mg/L) and six additional dyes.

Azo dyes in clothing textiles can be cleaved into a series of mutagenic aromatic amines which are not regulated yet

Azo dyes represent the by far most important class of textile dyes. Their biotransformation by various skin bacteria may release aromatic amines (AAs) which might be dermally absorbed to a major extent. Certain AAs are well known to have genotoxic and/or carcinogenic properties. Correspondingly, azo dyes releasing one of the 22 known carcinogenic AAs are banned from clothing textiles in the European Union. In the present study, we investigated the mutagenicity of 397 non-regulated AAs potentially released from the 470 known textile azo dyes. We identified 36 mutagenic AAs via publicly available databases. After predicting their mutagenicity potential using the method by Bentzien, we accordingly allocated them into different priority groups. Ames tests on 18 AAs of high priority showed that 4 substances (22%) (CASRN 84-67-3, 615-47-4, 3282-99-3, 15791-87-4) are mutagenic in the strain TA98 and/or TA100 with and/or without rat S9 mix. Overall, combining the information from the Ames tests and the publicly available data, we identified 40 mutagenic AAs being potential cleavage products of approximately 180 different parent azo dyes comprising 38% of the azo dyes in our database. The outcome of this study indicates that mutagenic AAs in textile azo dyes are of much higher concern than previously expected, which entails implications on the product design and possibly on the regulation of azo dyes in the future.

Novel stimuli-responsive hydrogels derived from morpholine: synthesis, characterization and absorption uptake of textile azo dye

A new cationic monomer methacrylamido-4-(2-aminoethyl)morpholine, (MAEM) derived from morpholine was synthesized in a single step and characterized by FTIR, 1H and 13C NMR analyses. Through free radical aqueous polymerization, novel copolymeric hydrogels have been prepared successfully using methacrylamido-4-(2-aminoethyl)morpholine and acrylamide (Aam) as monomers. Later on SEM, FTIR, elemental analysis and TG instruments were used to characterize the obtained poly(acrylamide-co-methacrylamido-4-(2-aminoethyl)morpholine), poly(Aam-c-MAEM), hydrogels. Poly(Aam-c-MAEM) hydrogels were tested for swelling, diffusion and uptake of reactive orange, RO, anionic dye. In this regard, various adsorption kinetics and isotherm models as well as operation parameters were systematically examined and discussed in detail in relation to adsorption uptake such as pH of media, comonomer composition, adsorbent dosage, temperature, initial dye concentration and contact time. The description of adsorption process of RO on hydrogels was consistent with the pseudo-second-order model followed by Elovich and pseudo-first-order. The best fitting adsorption model was selected on the basis of R 2, in the order of: Temkin > D-R > Langmuir > Freundlich isotherm. The results obtained in this study demonstrate that poly(Aam-c-MAEM) hydrogels provide an excellent advantage for application of this hydrogel system in the removal of anionic textile dyes from wastewater.

Synthesis of cobalt-orthotitanate inverse spinel nano particles via a novel low temperature solvothermal method: structural, opto-electronical, morphological, surface characterization and photo-catalytical application in mineralization of Remazol Red RB 133

Synthesis of single phase cobalt-orthotitanate inverse spinel nano particles is reported for the first time via a novel solvothermal method at low calcination temperature at 400 °C. The pure phase cobalt-orthotitanate spinel nano particles were prepared using cobalt nitrate and titanium tetraisopropoxide (1:1 molar ratio) as cobalt and titanium sources. The synthesised Co2TiO4 nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, surface area analyses (Brauner–Emmett–Teller) (BET) and UV–Vis diffuse reflectance spectroscopy. The XRD results proved the formation of a single phase cobalt-orthotitanate (Co2TiO4) nanoparticles by calcination temperature of 400 °C. The FE-SEM results showed that nano particles possess a uniform spherical morphology with an average size of 51 nm. Porosity and specific surface area of cobalt-orthotitanate nano particles was measured by nitrogen adsorption using BET and the results showed surface area of 44.47 m2/g. DRS results showed an optical band gap value of 1.802 eV for cobalt-orthotitanate nano powder. An excellent performance as a nano photo-catalyst toward the degradation of Remazol Red RB 133 (RR133) as a single azo textile dye with excellent efficiency. Mineralization of RR133 by highly active cobalt-orthotitanate nano-catalyst coated on glass surface was applied and 97% TOC removal was observed. This is due to high electron–hole charge separation and high surface area of nano-catalyst.

Bacillus algicola decolourises more than 95% of some textile azo dyes

Textile effluents in natural waters pose environmental health problems if not treated to safe limits. Various bacterial species have the potential to degrade dyes. Here we studied the ability of Bacillus algicola to decolourise red, blue and yellow azo dyes. B. algicola was isolated from soil samples taken from a sanitary landfill site. Isolation and screening were performed using mineral salt medium. Dye-decolourising isolates were assessed in their capacity to decolourise dyes. Experiments were conducted at pH 6, 7 and 8, and 25, 35 and 45 °C. Phytotoxicity of the dyes and biodegradation products was assessed by seed germination tests. Results show that B. algicola gave the highest decolourisation at pH 8.0 and 25 °C in the presence of yeast extract as media supplement. B. algicola degraded the red and blue azo dyes by over 95%. The phytotoxicity results indicated that biodegradation products of the red and blue azo dyes were not toxic. Biodegradation products of the yellow dye were, however, toxic and considerably hindered germination. From these results, we infer that B. algicola has good potential for degrading and decolourising the red and blue test azo dyes.

Sol–gel preparation, structural, thermal and spectroscopic analyses, and opto-electronic and photocatalytic activities of normal spinel nickel cobaltite nano-powder for photo-degradation of Reactive Red RB

Nickel cobaltite nano-composites have been prepared by a modified sol–gel process using nickel–cobalt acetates as precursors and citric acid-monoethylene glycol as stabilizers followed by calcination at 400 and 650 °C in air. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and thermogravimetry (TG-DTG), and energy dispersive X-ray (EDX), Fourier transform infrared (FTIR) and UV–Vis diffuse reflectance (UV–Vis DRS) spectroscopies were used for structural, thermal, and opto-electronic characterization of the prepared nano-powders. XRD results showed that using acetate as precursor and calcination at 400 °C results in a pure nickel cobaltite phase (NiCo2O4), while at 650 °C, nickel cobaltite with NiO impurity is produced. The nano-structured nickel cobaltite photocatalyst was composed of nano-size crystalline phases with an average size of 25 nm. The optical band gap energy of the nano-structured nickel cobaltite photocatalyst was 2.00 (640) and 3.20 eV (387.5 nm) from the UV–Vis DRS absorption spectra. The photo-catalytic activity of the synthesized nickel cobaltite nano-composite photo-catalysts for degradation of Reactive Red RB azo textile dye was examined. The nano-structured nickel cobaltite photocatalyst exhibited high photocatalytic activity for the photo-degradation of Reactive Red RB which is related to the optical absorption in the visible (640 nm) and UV (387.5 nm) irradiation, electron–hole separation and high surface area of the nano size particles (average size of 25 nm).

Adsorption of Acid Yellow 42 dye on calcined layered double hydroxide: Effect of time, concentration, pH and temperature

The adsorption of textile dyes onto Layered Double Hydroxides (LDH) and their thermally decomposed products is a promising strategy for the treatment of contaminated effluents - combining high removal efficiency with reasonable cost. The main purpose of this paper was to investigate the adsorption of textile azo dye Acid Yellow 42 (AY) onto calcined and uncalcined Mg-Al-CO3-LDH. A set of analytical techniques was used to characterize the materials, namely X-ray diffraction (XRD), Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), thermogravimetric analyses (TGA), N2 adsorption-desorption isotherms and Scanning Electron Microscopy (SEM). In the study of azo dye adsorption, the following factors were assessed: kinetics, adsorption capacity, effect of temperature, initial pH value, and recyclability of the adsorbent material. The adsorption capacity of calcined LDH (CLDH) was almost four times greater than that of the LDH precursor: 1266mg·g−1 (1.669mmol·g−1) and 330.0mg·g−1 (0.4350mmol·g−1), respectively, at pH equal to 7.0 and 25°C. The greater adsorption capacity for CLDH is related to the recovery property of these materials in light of the so called “memory effect”, which allows an intercalation process of the anionic dye, as demonstrated by XRD data.

Textile dye removal using experimental wetland ponds planted with common duckweed under semi-natural conditions

The study assesses the performance of experimental wetland pond systems vegetated by Lemna minor L. (common duckweed or lesser duckweed) for textile azo dye removal. The objectives are to assess the influence of L. minor on water quality parameters, compare the dye and chemical oxygen demand (COD) removal of four dyes (Acid Blue 113, Reactive Blue 198, Direct Orange 46 and Basic Red 46) with each other, and monitor the effect of dye accumulation as a function of the relative growth rate (RGR) of L minor. Findings indicate that the simulated shallow pond systems remove BR46 (low concentration) significantly (p < 0.05) higher than other dyes, and the ponds containing L. minor outperformed control ponds by around 51% in mean removal efficiency with a potential of L. minor for phytoremediation of approximately 13% efficiency. (Less)

Response surface methodology mediated optimization of textile azo dye, Eriochrome Black T decolorization by Bacillus cereus RC1

Response surface methodology mediated optimization of textile azo dye, Eriochrome Black T decolorization by Bacillus cereus RC1