Azo Dye Concentration Research Articles

The development of Giant reed biochar for adsorption of Basic Blue 41 and Eriochrome Black T. azo dyes from wastewater

The textile industry is discharging high concentrations of anionic and cationic azo dyes into the nearby environment, which can cause adverse effects on public health, and the aquatic environment. Therefore, this study aimed to develop giant reed biochar and apply for the removal of Basic blue 41 (BB41) and Eriochrome black T (EBT) azo dyes from water. Characterization techniques such as BET surface area analyzer, Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermal gravimetric analyzer (TGA) were applied for biochar description. The biochar exhibits a high fixed carbon content (80.4%), a low ash content (3.8%), a large surface area (429.0 m2/g), and good thermal stability. High removal efficiencies of BB41 98.6% and EBT 82.5% were recorded at the specific experimental condition. The experimental data were fitted with the Langmuir isotherm model at R2 0.99 for both dyes whereas the adsorption kinetics revealed the pseudo-second-order kinetics at R2∼\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sim$$\\end{document} 1 and 0.99 for BB41 and EBT, respectively. Furthermore, four regenerations of biochar with adsorption performances of BB41 and EBT dyes were found to be 94.7% and 79.1%, respectively. Finally, this adsorbent can be considered an economically viable material for the removal of synthetic dyes from wastewater systems. In conclusion, the study findings showed that the adsorbent material is promising to apply for water and wastewater treatment but still, the study of adsorption interaction and modifications of the surface functionalities are essential to accommodate multipollutant removal from real water systems.

Efficient removal of direct dyes by SA-Er biopolymer gel spheres: Equilibrium isotherms, kinetics and regeneration performance study

Biomass-based adsorbent materials are characterized by their low cost, environmental friendliness, and ease of design and operation. In this study, biomass-based hydrogel microspheres erbium alginate (SA/Er) with high stability and adsorption properties were prepared by a one-step synthesis method. The prepared materials were characterized and analyzed by SEM-EDS, XRD, TGA, FT-IR, UV–Vis, BET-BJH and XPS, and the adsorption performance of SA/Er was investigated for high concentrations of azo dyes in water. The results showed that the adsorption performance of SA/Er on the azo dyes of direct violet N (DV 1) and direct dark green NB (DG 6) with concentrations of 850 mg/L and 1100 mg/L under the optimal conditions was very high, and the adsorption amount could be up to 692 mg/g and 864 mg/g, respectively. The adsorption process was in accordance with the quasi-secondary kinetic model, which was accomplished by physical and chemical adsorption; the Langmuir isothermal model was able to better respond to the adsorption equilibrium, and the adsorption was dominated by the adsorption of surface monolayers; after seven desorption cycles, the removal of both azo dyes by the adsorbent material could reach >79.7 %. Combined with the results of FT-IR, UV–vis and XPS analysis before and after the adsorption, it was revealed that the adsorption of SA/Er with the dye molecules mainly consisted of hydrogen bonding, electrostatic adsorption and surface complexation, which resulted in the significant adsorption effect on the two azo dyes, and the above results can provide a reference for the treatment of dye wastewater.

Effective removal of toxic mixed azo dyes and Cr (VI) ions from wastewater using an integrated approach

The textile industry generates a significant amount of wastewater, including hazardous dyes, pigments, and heavy metals. The integrated approach of isolated bacterial strain and the bacterially synthesized ZnO nanoparticles was used in the removal of mixed azo dyes and Cr(VI) in a lab-scale bioreactor. It resulted in 77.19 % bromocresol purple (4th day), 50.11 % on bromocresol blue (3rd day), and 50.59 % bromocresol green (4th day) removal. Mixed azo dyes and Cr(VI) were removed using bacterial strain, which showed the maximum removal of Cr(VI) was 73.6 % at 25 ppm (3rd day) and mixed azo dyes removal was a maximum of 49.01 % at 75 ppm. A lab-scale reactor study using bacterial strain resulted in 45.89 % (5th day) of mixed azo dye and Cr(VI) removal. However, when the reactor was employed with synthetic wastewater and bacterially synthesized ZnO nanoparticles, achieved a maximum removal of 53.84 % at 120 min. Also, a phytotoxicity study on the Cicer arietinum plant with different concentrations of mixed azo dyes and chromium concentrations showed a maximum length of 5.5 cm at 100 ppm (3rd day). The bacterial strain and synthesized ZnO nanoparticles integrated technique providing an economically viable and scale-up solution for wastewater treatment techniques.

In-situ homeotropic alignment of dye doped liquid crystal molecules on multilayered self assembled nanoparticles in confined cells for next generation display devices

The in-situ homeotropic alignment (HA) of pure liquid crystal (LC) and dye doped LC molecules was prepared on the multilayered self assembled silica nanoparticles (SNPs) deposited on the substrates in a confined empty ITO cell. The LC and azo dye mixtures with (0.0625–0.5 wt%) concentrations show the uniform in-situ HA of nematic LC (NLC) over SNPs coated surface. The surface morphology with mapping of elements and functionality of the SNPs coated ITO glass substrate were confirmed by “field emission scanning electron microscope (FESEM)” and “X-ray photoelectron spectroscopy (XPS)”. Polarized optical microscopic textures and conoscopic view of pure and dye doped LC mixtures in SNPs coated confined cells, confirmed the HA of LC molecules and exhibited the uniform black textures under crossed polarizers. The electro-optic behaviour of dye doped homeotropically aligned LC (HALC) cells was compared to pure SNPs coated HALC cell. The results showed that on increasing the azo dye concentration (0.0625–0.25 wt%), the threshold (Vth) and operating (Vo) voltages were found decreased. However, on further increase of dye concentration to 0.5 wt%, Vth and Vo were observed relatively increased. The contrast ratio (CR) was found improved in dye doped HALCs with maximum CR at lowest dye concentration (0.0625 wt%). The UV results exhibit higher absorbance of the dye doped HALC cells with increasing the dye concentration. Also, the band gap values showed that the addition of even small amount of dye, it reduced the value of band gap in HALC cell.

Garlic Cellulosic Powders with Immobilized AgO and CuO Nanoparticles: Preparation, Characterization of the Nanocomposites, and Application to the Catalytic Degradation of Azo Dyes.

Nanomaterials have attracted specific consideration due to their specific characteristics and uses in several promising fields. In the present study, Chondrilla juncea was employed as a biological extract to facilitate the reduction of copper and silver ions within garlic peel powders. The resulting garlic-CuO and garlic-AgO nanocomposites were characterized using several analytical methods including FTIR, TGA/DTG, SEM, TEM, and XRD analyses. The garlic peel exhibited a rough surface. The nanoparticles were evenly dispersed across its surface. The incorporation of CuO and AgO nanoparticles affected the crystal structure of garlic peel. The establishment of CuO and AgO nanoparticles was evidenced by the highest residual mass values observed for the prepared nanocomposites. The thermogravimetric analysis showed that the prepared nanocomposites had lower thermal stability compared with garlic peel powders. The prepared nanocomposites were used for catalytic degradation of naphthol blue black B and calmagite. The decolorization process depended on the quantity of H2O2, initial concentration of azo dyes, duration of contact, and temperature of the bath. The calculated activation energy (Ea) values for the garlic-CuO nanocomposites were found to be 18.44 kJ mol-1 and 23.28 kJ mol-1 for calmagite and naphthol solutions, respectively. However, those calculated for garlic-AgO nanocomposites were found to be 50.01 kJ mol-1 and 12.44 kJ mol-1 for calmagite and naphthol, respectively.

Removal of Azo Dyes from Water Using Natural Luffa cylindrica as a Non-Conventional Adsorbent.

Reducing high concentrations of pollutants such as heavy metals, pesticides, drugs, and dyes from water is an emerging necessity. We evaluated the use of Luffa cylindrica (Lc) as a natural non-conventional adsorbent to remove azo dye mixture (ADM) from water. The capacity of Lc at three different doses (2.5, 5.0, and 10.0 g/L) was evaluated using three concentrations of azo dyes (0.125, 0.250, and 0.500 g/L). The removal percent (R%), maximum adsorption capacity (Qm), isotherm and kinetics adsorption models, and pH influence were evaluated, and Fourier-transform infrared spectroscopy and scanning electron microscopy were performed. The maximum R% was 70.8% for 10.0 g L-1Lc and 0.125 g L-1 ADM. The Qm of Lc was 161.29 mg g-1. Adsorption by Lc obeys a Langmuir isotherm and occurs through the pseudo-second-order kinetic model. Statistical analysis showed that the adsorbent dose, the azo dye concentration, and contact time significantly influenced R% and the adsorption capacity. These findings indicate that Lc could be used as a natural non-conventional adsorbent to reduce ADM in water, and it has a potential application in the pretreatment of wastewaters.

Activated rice husk biochar for azo dye removal: batch adsorption, kinetics and thermodynamic studies

<p>The study aimed to analyze the adsorption behaviour of an activated rice husk biochar adsorbent in batch mode to expunge azo dye concentrations depletion from liquid solvents. The biochar adsorbent was formulated using different chemical synthesis processes, and its surface region was assessed using Nitrogen retention. The existence of the particular azo dyes was verified through SEM and EDX examinations. Additionally, XRD analysis was conducted to examine the intensity and crystalline structure of the activated biochar adsorbent. A batch mode study was conducted to ascertain the ideal adsorption parameters, including pH, contact time, biochar dose, and azo dye concentration. The adsorption kinetic studies supported the notion of a favourable adsorption interaction occurring through the mutual influence of the adsorbed matter and the adsorbing substrate. Most isotherm studies were well-fitted with regression values of isotherm models, indicating an adsorption process with non-uniform monolayer formation. Thermodynamic investigations validated that the binding forces between the adsorptive and the adsorbing phase are endothermic, and a significant amount of spent adsorbent was successfully recovered using a strong hydrochloric acid desorption process.</p>

Smartphone-based procedure to determine content of single synthetic dyes in food using the Arata-Possetto extraction method

The use of additives, including dyes, is common in the preparation of food products. The analytical control of artificial food dye content is relevant since some, such as azo dyes, may produce cancer and attention deficit disorders and hyperactivity in children. Consequently, the maximum permitted concentration of azo dyes in food is regulated by current legislation. Therefore, it is of interest to find simple and fast procedures for the control of these compounds. The aim of this study is to determine the concentration of azo dyes in food samples by the Arata-Possetto method – based on the extraction of azo dyes employing natural wool –, followed by the analysis of an image captured by a smartphone camera. After experimentally determining the optimal extraction conditions, the calibration curves for standard solutions of different food dyes and the color of the dyed wool were obtained. Results from dyed wool image processing were compared with the absorbance spectra of the solutions before extraction as measured by a diode array spectrophotometer. The spectrophotometric and the image processing procedures were employed to obtain the calibration curves for different food dyes, which were subsequently employed to analyze food samples. Statistical treatment shows that the results of both methods are comparable.

Biocatalytic decolorization of azo dye-containing wastewater by immobilizing metagenome-derived laccase on green synthesized Co-doped NiO NPs

Efficient removal of toxic dyes from wastewater is crucial for environmental protection. Laccases are enzymes that have been proposed as potential solutions to reduce the devastating effects of toxic dyes with recalcitrant structures present in complex wastewater. However, instability of laccases has been identified as a major issue. This study aimed to develop a carrier matrix based on Co-doped NiO NPs to improve the stability of the metagenome-derived laccase PersiLac1 and achieve high removal efficiency of Azo dye-containing wastewater. The immobilization of laccase led to improved enzymatic activity over a broader range of pH and temperature. After 15 reuse cycles, the immobilized enzyme retained 57.99 % of its initial activity. The immobilized enzyme demonstrated great potential for the biodecolorization of Congo red over broad pH and temperature ranges, with 66.23 % decolorization achieved after 60 min under optimal conditions. Treatment with real textile wastewater containing an extremely high concentration of Azo dye resulted in more than 92 % dye removal. After 20 cycles of operation, the immobilized enzyme retained 87.66 % of its initial decolorization capability. This study presents Co-doped NiO NPs-PersiLac1 as an efficient, stable, and cost-effective biocatalytic system for Azo dye-containing removal processes in textile effluents.

The efficiency of Fenton, Fenton/MW and UV/oxidant processes in the treatment of a mixture of higher concentrations of azo dyes

The concentration of dyes in the degradation process, as found in the literature, higher than 10 – 30 ppm is rarely found in the literature. The present study attempts to establish the degradation efficiency of a mixture of two azo dyes, Acid Blue 29 and Ponceau Xylidine at higher concentrations by Fenton, Fenton-type, photolysis and microwave assisted Fenton processes, employing hydrogen peroxide (HP) and sodium persulphate (SPS) as oxidants. It was observed that mixing of dyes enhances decolorisation and retards chemical oxygen demand (COD) and total organic carbon (TOC) removal in Fenton process. Nevertheless, COD removal efficiency (CODeff) was higher at pH 3 than at pH 5.9, the respective values being 72.8 and 61.2% in 300 min. Although, the COD removal in Fe2+/HP system was faster in the early stages than in UV/HP system, the later shows higher CODeff than the former (96.6 and 72.8%, respectively, in 300 min). This result is in good agreement with the consumption pattern of HP in both systems. Although contradicting in nature, our finding, that the inhibition of degradation by persulphate, is remarkable. Although, microwave (MW) irradiation accelerated Fenton process, the overall COD removal was not increased. The effect of inorganic ions and hydroxylamine on the Fenton process has been reported in this study. Toxicity assessment by both colony forming units (CFUs) and light loss method shows that the detoxification efficiency of different processes are in the order UV/HP>Fe2+ /HP.

Influence of the azo-dye amaranth on the trophic structure of activated sludge in a model experiment.

The textile industry generates significant amounts of wastewater containing high concentrations of azo dyes. An important point in the process of purification of azo dyes is their influence on the activated sludge (AS) in wastewater treatment plants. Azo dyes, such as amaranth, play the role of xenobiotics. This article seeks to answer the question of how organisms manage to respond to xenobiotics remains very important and open, i.e., how they will react to toxic conditions. The aim of this research was to study how these changes are expressed in terms of the different trophic levels of AS. In our experiment, it was found that the dominant trophic units are significantly changed due to the xenobiotic entering the system. The data reveal the significant development of the bacterial segment (genusPseudomonasand azo-degrading bacteria) at times of large amaranth removal. In the most active phase of amaranth biodetoxification (48h), the culturable bacteria of the genus Pseudomonas change by about 40%, while the azo-degrading bacteria change by about 2%. Fauna organisms have a sharp change in the dominant groups-from attached and crawling ciliates and testate amoebas to the mass development of small and large flagellates. This is of great importance because micro- and metafauna play an important role in the detoxification process by ingesting some of the xenobiotics. This role is expressed in the fact that after dying, macro-organisms release this xenobiotic in small portions so that it can then be effectively degraded by adapting to the amaranth biodegradation bacteria. In this study, it is clear that all these events lead to a decline in the quality of AS. But on the other hand, these allow AS to survive as a microbial community, and the fauna segment does not disappear completely.

Valorization of Annona reticulata biochar by chitosan for the adsorption of Azo dye from Textile effluent

<p>Azo dye is a synthetic aromatic dye which are direct dye frequently used in textile industry to colour fibres. It also contributes to the damage of the environment. This study examines the adsorption biochar made from Annona reticulata to remove azo dye from textile wastewater. To improve the adsorption capacity, biochar valorized by chitosan molecules, Investigations were conducted on the use of chitosan-based materials that are acid-resistant for azo dye adsorption. In the batch experiment, basic operating parameters such as initial Azo dye concentrations, pH, contact time and bed height were assessed. The percentage removal efficiency for Azo dye was recorded as 67.18%, 75.88% and 94.37% for three dissimilar sized columns that were 6cm, 8cm, and 10cm. The UV–visible absorption spectroscopy was used to quantify the decolorization of dyes. The changed surface properties of the adsorbent produced from Annona reticulata were characterized by using SEM, XRD, and FTIR. The effectiveness of the column's adsorption was calculated mathematically by Yoon-Nelson, Thomas, and Adams-Bohart models. The model that best represents equilibrium isotherm data by adsorption had R2 values of 94.63, 86.67 and 96.35 respectively.</p>

Batch and Packed Bed Column Studies of Azo Dyes Adsorption from the Aqueous Solutions Using Activated Sugarcane Bagasse Charcoal Adsorbent: Isotherm and Kinetic Studies

<p>Biosorption of azo dyes (RO-16, RB-120 & RB-19) from the aqueous solutions was investigated using the activated sugarcane bagasse charcoal adsorbent. The characteristics of the prepared adsorbent were analyzed by SEM, EDX, FTIR, XRD, TG & DT analysis, and the BET surface area of the sugarcane bagasse adsorbent was examined by N2 adsorption and desorption techniques. Batch adsorption studies were performed to determine the optimum pH, azo dye concentration, sugarcane dose & temperature, and both Langmuir & Freundlich isotherm studies fit well with the adsorption process. Packed bed column adsorption studies confirmed the earlier breakthrough of the adsorption process, and the column adsorption studies fitted with Thomas, Yoon-Nelson, BDST and Adams-Bohart models. The desorption studies were conducted by adding various concentrations of sulfuric acid, and regeneration of spent azo dyes was done by different cycles.</p>

Degradation efficiency of the azo dye acid orange 2 and microbial community characteristics in a rotating algal biofilm reactor

Under the traditional suspended culture system for algae, processing high concentrations of azo dyes is difficult because of poor light transmittance in wastewater. The rotating algal biofilm (RAB) system enables algal biofilms to receive adequate light, even in the presence of high concentrations of dye. The degradation efficiency of acid orange 2 (AO-2) at concentrations of 50–600 mg/L exceeded 95 % within 12–24 h, and the highest removal rate was 592.35 mg/(L·d). Fourier transform infrared spectroscopy showed that the azo bond was broken in AO-2, and the main decomposition products were amines and olefins. The sulfate concentration did not influence the AO-2 removal, whereas the pH had a significant effect (P < 0.001). The dye degradation efficiencies under acidic and neutral conditions were higher than those under alkaline conditions. Decolorization experiments indicated that the extracellular and intracellular enzymes synergistically degraded AO-2. High-throughput sequencing revealed that biofilms in RAB reactors contained a variety of taxa, including cyanobacteria, bacteria, Rotifera, and Cercozoa. The potential cause of AO-2 biodegradation by algae-bacterial systems is that the biofilm can use AO-2 as a nitrogen source for its own growth.

Aliphatic oxime 3-(hydroxyimino)pentan-2,4-dione as new potential mediator for laccase-catalyzed decolorization of dyes

Aliphatic oxime HIPD (3-(hydroxyimino)pentan-2,4-dione) was studied as mediator of laccase (from Trametes versicolor) catalyzed decolorization and detoxication of eight structurally diverse synthetic dyes with typical chromophores including the azo dyes (Acid Red 1, Methyl Orange and Mordant Blue 13), indigo dye (Indigo Carmine), triphenylmethane dyes (Methyl Green, Crystal Violet), anthraquinone dye (Reactive Blue 4) and thiazine dye (Methylene Blue). The results demonstrated the potential and limitations of using 3-(hydroxyimino)pentane-2,4-dione as mediator for enzymatic decolorization of various type dyes. In the presence of a laccase-mediator system almost 100 % biodegradation was observed for Indigo Carmine, Acid Red 1, Methyl Orange and Reactive Blue 4 within 3 h. At the same time, the proposed laccase-mediator system does not decolorize Methylene Blue and exhibits lower efficiency in the degradation of triphenylmethane dyes in comparison with azo dyes. The studied system can be used repeatedly for wastewater treatment. Phytotoxicity tests of the solutions before and after treatment with laccase-mediator system indicated that dyes are converted into low-toxicity metabolites. The proposed system has demonstrated its efficiency in the treatment of artificial wastewater containing high concentrations of azo dyes (0.5 g L−1) and other auxiliaries used in the textile industry. Color reductions of 92 % and 83 % were achieved using laccase-mediator system for Acid Red 1 and Methyl Orange for 7 days in the presence of dye bath components.

Efficient removal of azo dyes by Enterococcus faecalis R1107 and its application in simulated textile effluent treatment

This study aimed to exploit the potential of Enterococcus faecalis R1107 in the bioremediation of azo dyes. The maximal decolorization of Congo Red (CR), Reactive Black 5 (RB5), and Direct Black 38 (DB38) were 90.17%, 96.82%, and 81.95%, respectively, with the bacterial treatment for 48 h. 65.57% of CR and 72.64% of RB5 could be decolorized by E. faecalis R1107 within 48 h when the concentration of azo dyes increased up to 1000 mg/L. FTIR analysis confirmed that E. faecalis R1107 could effectively break down the chemical structures of three azo dyes. E. faecalis R1107 alleviated the phytotoxicity of azo dyes and improved seed germination, which contributed to the increase in the lengths of roots, stems, and leaves of Vigna radiata seedlings. Transcriptomic analysis suggested that the gene regulatory networks in E. faecalis R1107 synergistically improved the degradation and detoxification of RB5, including the major metabolic pathways, the secondary metabolism, the transport system, the amino acid metabolic pathways, and the signal transduction systems. Simulated textile effluent (STE) was used to mimic real textile effluent to evaluate the bioremediation potential of E. faecalis R1107, and 72.79% STE can be decolorized after E. faecalis R1107 treatment for 48 h. In summary, our study demonstrated that E. faecalis R1107 might be well suitable for potential applications in the bioremediation of textile effluent.

Synthesis, characterization and nonlinear optical properties of polylactide and PMMA based azophloxine nanocomposites for optical limiting applications

The widespread usage of harmful pulsed laser sources emitting brief but intense radiations implies to search for appropriate and convenient forms of protection. Nonlinear optical nanomaterials can serve this purpose when properly embedded in a solid medium, resulting in nanocomposite passive optical limiting filters.This article focuses on the optical limiting behavior of a series of polymer-dye nonlinear nanocomposites, for which we combined azophloxine, a red azo dye, with two polymer hosts, namely polymethyl methacrylate (PMMA) and polylactide (PLA). In this work, optical filters were produced by chemical synthesis from the bulk. Their linear absorption and transmittance were measured by UV–VIS-NIR spectrophotometry and their thermal examination was done via TGA measurements. The optical limiting properties were characterized using an appropriate custom-made optical setup and the nonlinear absorption coefficients and refractive indices were measured by the Z-scan method. Optical measurements in the nonlinear regime were performed at the wavelength of 1064 nm with nanosecond pulses at a low pulse repetition rate. The nonlinear optical properties resulting from energy dependent transmittance assessments reveal that the dye concentration is of major relevance regarding the PMMA nanocomposites, and to a lesser extend for the PLA based systems. The PLA synthesis concept described in this study offers an easy way to directly attach the dye covalently to the polymer chain. The originality and novelty of this synthesis technique is to be pointed out since it has never been mentioned elsewhere to date. For the various types of nanocomposites investigated, significant differences in the optical limiting response were observed. For instance, it is averred that a significantly higher optical limiting effect results in the systems with the less azo dye concentration and the best optical limiting performance corresponding to a laser protection level of OD = 3.3 was measured for the PLA based system. Besides, the PMMA nanocomposite system exhibits an optical limiting level of OD = 1.9. A molecular model claiming for the dye aggregation in the PMMA nanocomposites is discussed. Two different absorption regimes responsible for the optical limiting action have been identified to be reverse saturable (RSA) – excited state absorption (ESA) on the one hand and multi-photons absorption (MPA) on the other hand. By means of transmittance investigations in an open Z-scan configuration, one could observe the sudden and remarkable changeover from a saturable absorption (SA) regime to a reverse saturable absorption one for high azo dye loads in PMMA. Such transition from SA to RSA has been basically revealed for materials and experimental conditions close to or centered on the resonance of absorption (i.e. around 532 nm). To the author’s knowledge, a study in off-resonant conditions (i.e. 1064 nm) was never reported elsewhere to date. Also tracked out by open Z-scan measurements, significantly higher nonlinear absorption coefficients βresulted for the PLA based systems. Similar experiments in a close aperture Z-scan scheme revealed nonlinear refractive indexes in the order of n2=-2.0X10-15cm2/W for the PMMA nanocomposites and n2=-3.0X10-15cm2/W for the PLA nanocomposites.

Decolourization of azo dye using a batch bioreactor by an indigenous bacterium Enterobacter aerogenes ES014 from the waste water dye effluent and toxicity analysis

Effluents of textile industries caused serious environmental problem throughout the world. In this study, a total of 23 bacterial strains from five bacterial species were isolated from the dye effluent. Of these strains, a unique and novel Enterobacter aerogenes ES014 was utilized for dye decolourization and toxicity analysis. The selected strain could effectively decolourize three selected azo dyes. It showed the capability for decolourizing acid orange (82.3 ± 3.6%), methyl orange (78.2 ± 3.3%), and congo red (81.5 ± 3.2%). The selected bacterial strain significantly decolourized 100 mg/L acid orange at 35 °C, pH 7.5 with 6% sodium chloride concentration. Most of the tested nitrogen and carbon sources effectively enhanced decolourization process. It showed the ability to decolourize acid orange in the culture medium containing 1.5% glucose (100 ± 2.8%) and 0.8% beef extract (100 ± 3.1%). A laboratory-scale batch bioreactor was used to decolourize azo dye at optimized culture conditions. The decolourizing ability improved with 100 mL/h hydraulic retention time. The treated wastewater quality was improved due to sharp depletion of Total Dissolved Solids (TDS), pH, Chemical Oxygen Demand (COD), alkalinity and sulphate concentration. The selected bacteria has the potential to produce dye degrading laccase. Laccase was detected during fermentation process in batch bioreactor as a key enzyme for decolourization produced by E. aerogenes ES014. Phytotoxicity and acute toxicity analysis were performed using Arachis hypogaea (pea nut) seed and first instar larvae of Artemia parthenogenetica (brine shrimp). The seed germination rate of treated wastewater was improved (94.3 ± 1.8%) and enhanced survival rate (91.7 ± 2.9%) in the first instar Artemia larvae treated with wastewater after 24 h. Overall, E. aerogenes ES014, might be a promising bacterial strain for the treatment of textile effluents with high azo dye concentrations.

Treatment of textile wastewater containing mixed toxic azo dye and chromium (VI) BY haloalkaliphilic bacterial consortium

Scientific empowerment in this century created a positive and negative impact on the ecosystem's biotic and abiotic components. The current scenario of emerging recalcitrant pollutants in the environment is encountered using various remediation approaches are enforced and applied. The need for mineralization of the toxic pollutants to non - toxic forms accomplished the application of microbes (bacteria, fungi and algae) and plants individually or in a combined manner. The current research on the removal of pollutants from synthetic textile wastewater containing 1200 ppm concentration of mixed azo dyes –Reactive red (RR), Reactive Brown (RB) & Reactive Black (RBl) and 300 ppm Cr (VI) metal using haloalkaliphilic bacterial strains LBKVG1, LBKVG2, LBKVG3 & LBKVG4 in a Moving Bed Biofilm Reactor (MBBR), showed decolorization of 82 ± 0.5% of mixed azo dyes and degradation 56 ± 0.5% of Cr (VI) metal at 37 °C and pH 8.5 in the fifth day of the study. The isolated bacterial strains in the consortium were molecularly and morphologically characterized by 16SrRNA sequencing and SEM analysis. FT-IR and GC-MS analysis scrutinized the metabolites obtained. The findings suggest the degradation of hazardous pollutants even at higher concentrations and attempt to decolourize the mixed azo dyes simultaneously using the eco-friendly bacterial consortium.

Catalytic degradation of acid red B in the system of ultrasound/peroxymonosulfate/Fe3O4

The wastewater containing azodyeswastewater features high chroma, difficult degradation and great harm to the environment. It is difficult to meet the increasingly stringent requirements for industrial wastewater discharge using traditional water treatment methods. In this paper, degradation of Acid Red B in the system of ultrasound/peroxymonosulfate/Fe3O4 was investigated. The effects of Fe3O4 dosage, peroxymonosulfate dosage, ultrasonic power, ultrasonic frequency, initial azo dye concentration and initial pH value on degradation were studied through orthogonal experiments. Besides, through single factor experiment, the influence of various factors on the degradation was determined in the system of ultrasound/peroxymonosulfate/Fe3O4. Ethanol and tert-Butanol were used to study the dominant radicals in the system. NaH2PO4, NaHCO3 and NaCl were added to study the degradation effect of inorganic anions on acid red B. Finally, ultraviolet–visible spectrophotometer was used to scan the spectrum to analyze the degradation path of acid red B in the system of ultrasound/ peroxymonosulfate/Fe3O4. The results indicate that proposed method is of great potential application value in removal of organic pollution and environmental purification.