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 (genus Pseudomonas and azo-degrading bacteria) at times of large amaranth removal. In the most active phase of amaranth biodetoxification (48 h), 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.

A novel textile dye degrading extracellular laccase from symbiotic bacterium of Bacillus sp. CF96 isolated from gut termite (Anacanthotermes).

Oxidation of phenolic compounds is an urgent need in textile industry, biological refinements, pulp and paper production. In present study, a laccase was purified from symbiotic bacterium of Bacillus sp. CF96 existing in termite digestive system. The extracellular laccase was purified via amnion sulfate precipitation, membrane dialysis, and ion exchange chromatography. The results showed that the Bacillus CF96 laccase possesses a molecular mass of 63 kDa, an optimal pH and temperature of 8.0 and 60 °C. Results showed that Zn2+, Mn2+ and Fe2+ were considered as the activator ions, while SDS was the main inhibitor. Using syringaldazine (SGZ) as substrate, the half-life of laccase at optimal temperature was 148 min; Km and Vmax were 0.737 µM and 100.5 U/mg. In addition, the enzyme showed a high effect on indigo dye with 90% bleaching capacity compared to control. In conclusion, the laccase has potential applications in industries under the provided optimal conditions.

Azoreductase activity of dye-decolorizing bacteria isolated from the human gut microbiota.

The gut microbiota enriches the human gene pool and contributes to xenobiotic metabolism. Microbial azoreductases modulate the reduction of azo-bonds, activating produgs and azo polymer-coated dosage forms, or degrading food additives. Here, we aimed to screen the healthy human gut microbiota for food colorant-reducing activity and to characterize factors modulating it. Four representative isolates from screened fecal samples were identified as E. coli (AZO-Ec), E. faecalis (AZO-Ef), E. avium (AZO-Ev) and B. cereus (AZO-Bc). Both AZO-Ef and AZO-Ev decolorized amaranth aerobically and microaerophilically while AZO-Ec and AZO-Bc had higher aerobic reduction rates. The isolates varied in their activities against different dyes, and the azo-reduction activity mostly followed zero-order reaction kinetics, with a few exceptions. Additionally, the isolates had different pH dependence, e.g., AZO-Ec was not affected by pH variation while AZO-Bc exhibited variable degradation kinetics at different pH levels. Cell-free extracts showed NADH-dependent enzymatic activities 14-19 times higher than extracellular fractions. FMN did not affect the reducing activity of AZO-Ef cell-free extract, whereas AZO-Ec, AZO-Ev and AZO-Bc had significantly higher reduction rates in its presence (P values = 0.02, 0.0001 and 0.02, respectively). Using Degenerate primers allowed the amplification of azoreductase genes, whose sequences were 98-99% similar to genes encoding FMN-dependent-NADH azoreductases.

A re-circulating horizontal flow constructed wetland for the treatment of synthetic azo dye at high concentrations.

A re-circulating horizontal flow constructed wetland (RHFCW) system was developed in a greenhouse. This system was operated with Typha domingensis to study the phytoremediation capacity of this macrophyte species in different developing stages for synthetic textile wastewater with the pollutant type, the amaranth (AM) azo dye. Experiments were applied with a fixed flow rate Q = 10 L/h corresponding to a theoretical residence time of 3 h. The synthetic feeding to the RHFCW container was re-circulated back until the required water quality was achieved. The performance of this pilot-scale system was compared to an unplanted RHFCW. The effect of the initial dye concentration was studied using four dye concentrations (10, 15, 20, and 25 mg/L). The following parameters pH, color, COD, BOD5, NO3-, NO2-, and NH4+ were monitored during treatment. The maximum efficiencies obtained for discoloration, COD, NO3-, and NH4+ were 92 ± 0.14%, 56 ± 1.12%, 92 ± 0.34%, and 97 ± 0.17% respectively. Experiences demonstrate a decrease of removal efficiencies of studied parameters with the increase of dye concentrations, leading to an increase of the duration of treatment. Changes in activities of antioxidant enzymes (superoxide dismutase (SOD), guaiacol peroxidase (GPX), catalase (CAT), ascorbic peroxidase (APX), and glutathione reductase (GR)) and their relation to plant defense system against stress were studied. Enzymes were evaluated in leaves of T. domingensis during the remediation of the azo dye (amaranth). During treatment, an increase of enzymes activities was observed in accordance with the high removal efficiency.

Accelerating effects of humin on sulfide-mediated azo dye reduction.

As an important fraction of humic substances, humin has been found capable of stimulating bioreduction reactions. However, whether humin could promote abiotic reduction and the effects of coexisting soluble humic substance and insoluble mineral remained unsolved. In this study, a humin sample was isolated from a paddy soil. Cyclic voltammetry, electron paramagnetic resonance, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses of the humin indicated the existence of redox-active quinone moieties and other oxygen-containing groups. The humin could be reduced by sulfide and its presence stimulated the abiotic reduction of acid red 27 (AR27) and four other azo dyes by sulfide. In the presence of 100-1000 mg/L intact humin, the sulfide-mediated AR27 reduction efficiency in 7 d was enhanced from 56.3% to 92.5%. The stimulating behavior of intact humin was observed for 100-300 mg/L AR27 and increased with the increase of sulfide concentration (1.2-3.0 mM). Much higher stimulating effects were found with the presence of humin pre-reduced by sulfide. Moreover, for sulfide-mediated AR27 reduction, the coexistence of humin (500 mg/L) and humic acid (10-30 mg/L) or Wyoming sodium-montmorillonite (SWy-2, 1-4 g/L) led to better promotion activities than the presence of single component. And synergistic promotion of sulfide-mediated AR27 reduction was observed with coexisting humin and SWy-2 due to enhanced Fe(II) production. These findings extended our understanding of the influence of humin on reductive transformation of pollutants in the environment.

Effect of coating method on the structure and properties of a novel PbO2 anode for electrochemical oxidation of Amaranth dye.

This study deals with the electrochemical degradation of Amaranth in aqueous solution by means of stainless steel (SS) electrodes coated with a SiOx interlayer deposited by Plasma Enhanced Chemical Vapour Deposition and a modified PbO2 top layer deposited by continuous galvanostatic electrodeposition. The morphological characterization of the PbO2 top-layer performed by Field Emission Scanning Electron Microscope put in evidence that the SiOx, interlayer allows obtaining a more integrated PbO2/SS electrode with a very homogeneous PbO2 film. The composition of the lead oxide layer was investigated by X-ray Diffractometry, showing that the ß-PbO2/α-PbO2 ratio in the top layer deposited on the SiOx film was four times higher respect to the one deposited directly on the stainless steel surface. In addition, the electrochemical behaviour of SS/SiOx/PbO2 interfaces was studied by electrochemical impedance spectroscopy (EIS). The EIS results showed that the presence of SiOx favors electron transfer within the oxide layer which improves electro-oxidation capability. Moreover, bulk electrolysis showed that over 100% colour removal and 84% COD removal, using SS/SiOx/PbO2 at acidic pH were reached after 300 min. High Performance Liquid Chromatography analysis was used for the quantitative determinations of initial Amaranth dye molecule removal and to evaluate its specific degradation rate. In order to evaluate the phototoxicity of treated solution with different by-products, different tests of germination were performed and proved that the electrochemical treatment with modified PbO2 could be as an efficient technology for reducing hazardous wastewater toxicity and able to produce water available for reuse.

Selective and sensitive spectrophotometric method to determine trace amounts of copper metal ions using Amaranth food dye.

Copper is an essential element in some biological processes in organisms, so it was important to find ways to identify trace amounts of it. Minimal amounts of copper ions can be determined in aqueous solutions in the spectrophotometric method suggested in this study. The method depends on the reaction between Cu(II) and Amaranth dye at the pH 6.0. The gradual disappearance of Amaranth colour at 520 nm occurring with an increase of Cu(II) concentration from 0.13 up to 2.0 µg cm-3. The molar absorptivity coefficient and Sandell's sensitivity of the complex are found to be 0.94 × 104 L mol-1 cm-1, 6.8 ng cm-2 respectively. The advantages of this method are simple, selective, and highly sensitive. The method was used for determination of copper ions in aqueous solutions containing several metal ions, where excellent agreements between reported and obtained results were achieved in aqueous solutions containing copper metal ions only. The postulated method is in an excellent agreement with the determination of Cu(II) ion concentrations by atomic absorption spectroscopy (AAS). The interference was studied to determine the copper metal ions concentration, and do not interfere with eleven of other metal ions.

A versatile CeO2/Co3O4 coated mesh for food wastewater treatment: Simultaneous oil removal and UV catalysis of food additives.

Food waste water is one of the most urgent environmental problems for the close connection between food and our daily life. Herein, we use a simple hydrothermal method to prepare a highly efficient catalyst-CeO2/Co3O4 compound on the stainless steel mesh, aiming for food waste water treatment. Possessing the superhydrophilic property and catalytic ability under ultraviolet light, CeO2/Co3O4 coated mesh has successfully processed three representative contaminants in food wastewater, which are soybean oil (food oil), AR (food dye) and VA (food flavor) simultaneously with an one-step filtration. Besides, the mesh is stable in a wide pH range and performs well in reusability. Therefore, such a multifunctional material with simple preparation method, high processing efficiency and facile operation shows a promising prospect for practical production and application for food wastewater treatment.

Degradation of dye wastewater with a photoelectric integration process (MPEC): Microbial fuel cells-assisted dual electrodes thin-film photoelectrocatalytic.

A novel photoelectric integration process (MPEC) was developed to degrade Amaranth. In the MPEC, the output voltage of the microbial fuel cells (MFCs) was used to assist the dual slant-placed electrodes thin-film photocatalytic (PC). With two MFCs connected in series, the MPEC process realized the highest decolorization efficiency. It is close to that of the external bias photoelectrocatalytic (PEC), and 7% higher than that of the self-generated electric field-assisted photoelectrocatalytic (SPEC). The feasibility of MPEC pre-treatment and MFC post-treatment of Amaranth was investigated. The results demonstrated that MPEC pre-treatment of Amaranth could improve its biodegradability. The higher MPEC decolorization efficiency indicated the stronger biodegradability of the obtained intermediates and the higher MFC output voltage. When the MPEC decolorization efficiency was gradually increased to 50%, the removal efficiencies of total Chemical Oxygen Demand (COD) by the MPEC and MFC increased; when the decolorization efficiency was increased above 50%, the removal efficiencies became stable. MPEC enhanced the biodegradability efficiently and was applicable to pre-treat textile wastewater.

Colorimetric Microtiter Plate Assay of Polycationic Aminoglycoside Antibiotics in Culture Broth Using Amaranth.

We present a colorimetric method for the detection of aminoglycoside antibiotics such as neomycin (NEO) using a reddish anionic dye, amaranth (AR3-). Under acidic conditions, at which NEO exists in fully protonated form (NEOH6+), the AR3- anion associates with the NEOH6+ cation to form a precipitate, NEOH(AR)2. The precipitate was soluble in a buffer solution of pH 8.5, yielding a reddish solution with an absorption maximum at around 520 nm. Tobramycin and gentamycin, which exist as pentavalent cations under acidic conditions, gave almost the same results. On the other hand, kanamycin, amikacin and streptomycin, which would exist as tri- and tetravalent cations, were not precipitated. Thus, the AR3- anion could be considered to be an analytical reagent for specific aminoglycosides with polycationic functionality. However, since the precipitation reaction was considerably affected by other anions, a separation method using the tetraphenylborate anion was employed as a pretreatment. The separation method involves precipitating the polycationic aminoglycosides with the tetraphenylborate anion, washing the precipitate with acetonitrile, and re-precipitating the aminoglycosides as hydrochloride salts. Thus, the present method was applied to a microtiter plate assay of the products in an NEO-producing culture broth.

Electrochemical behavior of amaranth and its sensitive determination based on Pd-doped polyelectrolyte functionalized graphene modified electrode.

In this work, poly(sodium p-styrenesulfonate) (PSS)-functionalized graphene supported palladium nanoparticles (Pd) composites were fabricated with simple ultrasonic bath method. The morphology and structure of PSS-GR-Pd composites were characterized using UV-vis absorption spectra, X-ray diffraction and Transmission Electron Microscopy. By combining the merits of the PSS-GR and Pd NPs, a new electrochemical sensor was erected to detect amaranth based on the PSS-GR-Pd nanocomposites. The electrochemical behavior of amaranth was investigated systematically in 0.1molL-1 phosphate buffer solution (PBS 2.0). At the optimum parameter, Ipa was found to be linearly dependent on the concentrations of amaranth (1×10-7-9×10-6molL-1). The detection limit was 7nM (S/N=3) and sensitivity was 5.85µAµM-1. Finally, this system was utilized for determining amaranth in soft drink using the standard addition method.

Decolorization and mineralization of Amaranth dye using multiple zoned aerobic and anaerobic baffled constructed wetland.

The objective of this study is to determine the reduction efficiency of Chemical Oxygen Demand (COD) as well as the removal of color and Amaranth dye metabolites by the Aerobic-anaerobic Baffled Constructed Wetland Reactor (ABCW). The ABCW reactor was planted with common reed (Phragmite australis) where the hydraulic retention time (HRT) was set to 1 day and was fed with synthetic wastewater with the addition of Amaranth dye. Supplementary aeration was supplied in designated compartments of the ABCW reactor to control the aerobic and anaerobic zones. After Amaranth dye addition the COD reduction efficiency dropped from 98 to 91% while the color removal efficiency was 100%. Degradation of azo bond in Amaranth dye is shown by the UV-Vis spectrum analysis which demonstrates partial degradation of Amaranth dye metabolites. The performance of the baffled unit is due to the longer pathway as there is the up-flow and down-flow condition sequentially, thus allowing more contact of the wastewater with the rhizomes and micro-aerobic zones.

Binding and Inhibitory Effect of the Dyes Amaranth and Tartrazine on Amyloid Fibrillation in Lysozyme.

Interaction of two food colorant dyes, amaranth and tartrazine, with lysozyme was studied employing multiple biophysical techniques. The dyes exhibited hypochromic changes in the presence of lysozyme. The intrinsic fluorescence of lysozyme was quenched by both dyes; amaranth was a more efficient quencher than tartrazine. The equilibrium constant of amaranth was higher than that of tartarzine. From FRET analysis, the binding distances for amaranth and tartrazine were calculated to be 4.51 and 3.93 nm, respectively. The binding was found to be dominated by non-polyelectrolytic forces. Both dyes induced alterations in the microenvironment surrounding the tryptophan and tyrosine residues of the protein, with the alterations being comparatively higher for the tryptophans than the tyrosines. The interaction caused significant loss in the helicity of lysozyme, the change being higher with amaranth. The binding of both dyes was exothermic. The binding of amaranth was enthalpy driven, while that of tartrazine was predominantly entropy driven. Amaranth delayed lysozyme fibrillation at 25 µM, while tartrazine had no effect even at 100 µM. Nevertheless, both dyes had a significant inhibitory effect on fibrillogenesis. The present study explores the potential antiamyloidogenic property of these azo dyes used as food colorants.

Evaluating role of immobilized periphyton in bioremediation of azo dye amaranth.

The aim of this study was to evaluate the bioremediation capabilities of three kinds of periphyton (i.e. epiphyton, metaphyton and epilithon) immobilized in bioreactors to decolorize and biodegrade the sulphonated azo dye, amaranth. Results showed that periphyton dominated by phyla including Cyanobacteria, Proteobacteria and Bacteroidetes. Complete removal of dye was shown by all the biofilms periphyton (epiphyton showed highest removal efficacy) over a range of initial concentrations (50-500mgL-1) within 84h at pH 7 and 30°C. Biodegradation of amaranth was confirmed through FTIR and HPLC and the biodegradation pathways were detected by GC-MS/MS analysis. The azo bonds in the amaranth were successfully broken by periphyton and amaranth was converted to non-toxic, aliphatic compounds including isobutene, acetyl acetate and ethyl acetate. The results showed the potential application of immobilized periphyton at industrial scale for the removal of azo dyes from wastewater containing azo dye amaranth.

Adsorption of azo dyes from aqueous solution by the hybrid MOFs/GO.

In this work, a hybrid of chromium(III) terephthalate metal organic framework (MIL-101) and graphene oxide (GO) was synthesized and its performance in the removal of azo dyes (Amaranth, Sunset Yellow, and Carmine) from water was evaluated. The adsorption for azo dyes on MIL-101/GO was compared with that of MIL-101, and it was found that the addition of GO enhanced the stability of MIL-101 in water and increased the adsorption capacity. The maximum adsorption capacities of MIL-101/GO were 111.01 mg g(-1) for Amaranth, 81.28 mg g(-1) for Sunset Yellow, and 77.61 mg g(-1) for Carmine. The adsorption isotherms and kinetics were investigated, showing that the adsorption fits the Freundlich isotherm and the pseudo-second-order kinetic model. The recyclability of MIL-101/GO was shown by the regeneration by acetone. The high adsorption capability and excellent reusability make MIL-101/GO a competent adsorbent for the removal dyes from aqueous solution.

Spectroscopic and microcalorimetric studies on the molecular binding of food colorant acid red 27 with deoxyribonucleic acid.

Interaction of the food colorant acid red 27 with double stranded DNA was investigated using spectroscopic and calorimetric methods. Absorbance and fluorescence studies suggested an intimate binding interaction between the dye and DNA. The quantum efficiency value testified an effective energy transfer from the DNA base pairs to the dye molecules. Minor groove displacement assay with Hoechst 33258 revealed that the binding occurs in the minor groove of DNA. Circular dichroism studies revealed that acid red 27 induces moderate conformational perturbations in DNA. Results of calorimetric studies suggested that the complexation process was driven largely by positive entropic contribution with a smaller favorable enthalpy contribution. The equilibrium constant of the binding was calculated to be (3.04 ± 0.09) × 10(4) M(-1) at 298.15 K. Negative heat capacity value along with the enthalpy-entropy compensation phenomenon established the involvement of dominant hydrophobic forces in the binding process. Differential scanning calorimetry studies presented evidence for an increased thermal stability of DNA on binding of acid red 27. Copyright © 2016 John Wiley & Sons, Ltd.

Degradation of Amaranth azo dye in water by heterogeneous photo-Fenton process using FeWO4 catalyst prepared by microwave irradiation.

FeWO4 particles were synthesized by a simple, rapid and facile microwave technique and their catalytic properties in heterogeneous photo-Fenton reaction were evaluated. This material was employed in the degradation of Amaranth azo dye. Individual and interactive effects of operational parameters such as pH, dye concentration and H2O2 dosage on the decolorization efficiency of Amaranth dye were evaluated by 2(3) central composite design. According to characterization techniques, a porous material and a well-crystallized phase of FeWO4 oxide were obtained. Regarding the photo-Fenton reaction assays, up to 97% color and 58% organic carbon removal were achieved in the best experimental conditions. In addition, the photo-Fenton process maintained treatment efficiency over five catalyst reuse cycles to indicate the durability of the FeWO4 catalyst. In summary, the results reveal that the synthesized FeWO4 material is a promising catalyst for wastewater treatment by heterogeneous photo-Fenton process.

Rapid enhanced photocatalytic degradation of dyes using novel N-doped ZrO2.

A novel N-doped ZrO2 (N-ZrO2) photocatalyst is synthesized through thermal decomposition of zirconium hydroxide-urea complex and is characterized using various techniques, including XRD, FTIR, TGA, SEM, TEM, UV-DRS, XPS, XANES, and BET. The N-ZrO2 possesses pure monoclinic structure with high crystallinity. By using the proposed facile route of synthesis, both interstitial and substitutional N doping with high dopant stability can be realized. The optical properties of the catalyst are significantly altered after N doping, giving an optical response in the visible and near infrared regions and an additional strong absorption peak in the UVA region. The N-ZrO2 showed a higher photocatalytic activity than pristine ZrO2 for the degradation of amaranth (AM) and methylene blue (MB) under visible or UV light irradiation, which could be attributed to the band gap narrowing, higher specific area, smaller crystalline size, and higher availability of surface hydroxyl groups. Due to its molecular structure and light absorption characteristics, MB is easier to degrade than AM. Overall removal efficiencies, including adsorption and photolysis, for AM and MB by N-ZrO2 at pH 7 with initial dye concentration of 10 mg/L, catalyst concentration of 1 g/L, and visible light irradiation of 144.7 W/m(2) are 67.2 and 96%, respectively. Using UVA light of only 3.5 W/m(2) under identical experimental conditions, complete removal of MB and AM is obtained. The photocatalytically treated solution of either AM or MB is nontoxic against Bacillus cereus, an agriculturally important soil microorganism.

Exploration of binding of C.I. Food Red 9 with pepsin by optical spectroscopic and molecular docking methods.

A comprehensive study of the effects of C.I. Food Red 9 on the conformation and activity of pepsin was performed using multi-spectral methods and molecular docking technique. Fluorescence and circular dichroism spectral analyzes showed that C.I. Food Red 9 binding induced the changes of secondary and tertiary structure of pepsin. The activity experimental results indicated that the activity of pepsin decreased remarkably with the increasing concentration of C.I. Food Red 9. Multi non-covalent interactions including hydrogen bonds, hydrophobic, and electrostatic forces played important roles in the complex formation between C.I. Food Red 9 and pepsin. The binding constants of pepsin with C.I. Food Red 9 were (1.21±0.036)×10(4) L mol(-1) (298 K) and (1.05±0.043)×10(4) L mol(-1) (310 K). Moreover, the putative binding site of C.I. Food Red 9 on pepsin was near to activity pocket. This study demonstrates that C.I. Food Red 9 could cause some negative effects on pepsin.

Interaction of toxic azo dyes with heme protein: biophysical insights into the binding aspect of the food additive amaranth with human hemoglobin.

A biophysical study on the interaction of the food colorant amaranth with hemoglobin was undertaken. Spectrophotometric and spectrofluorimetric studies proposed for an intimate binding interaction between the dye and the protein. The dye quenched the fluorescence of the protein remarkably and the mechanism of quenching was found to be static in nature. Synchronous fluorescence studies suggested that the polarity around the tryptophan residues was altered in the presence of amaranth whereas the polarity around tyrosine residues remained largely unaltered. 3D fluorescence, FTIR and circular dichroism results suggested that the binding reaction caused conformational changes in hemoglobin. The negative far-UV CD bands exhibited a significantly large decrease in magnitude in the presence of amaranth. From calorimetry studies it was established that the binding was driven by a large positive entropic contribution and a small but favorable enthalpy change.