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.

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.

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 SiO_x 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 SiO_x, 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 β-PbO₂/α-PbO₂ ratio in the top layer deposited on the SiO_x film was four times higher respect to the one deposited directly on the stainless steel surface. In addition, the electrochemical behaviour of SS/SiO_x/PbO₂ interfaces was studied by electrochemical impedance spectroscopy (EIS). The EIS results showed that the presence of SiO_x 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/SiO_x/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.

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.

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.

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.

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.

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.

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.

Electron acceptor-dependent respiratory and physiological stratifications in biofilms

Bacterial respiration is an essential driving force in biogeochemical cycling and bioremediation processes. Electron acceptors respired by bacteria often have solid and soluble forms that typically coexist in the environment. It is important to understand how sessile bacteria attached to solid electron acceptors respond to ambient soluble alternative electron acceptors. Microbial fuel cells (MFCs) provide a useful tool to investigate this interaction. In MFCs with Shewanella decolorationis, azo dye was used as an alternative electron acceptor in the anode chamber. Different respiration patterns were observed for biofilm and planktonic cells, with planktonic cells preferred to respire with azo dye while biofilm cells respired with both the anode and azo dye. The additional azo respiration dissipated the proton accumulation within the anode biofilm. There was a large redox potential gap between the biofilms and anode surface. Changing cathodic conditions caused immediate effects on the anode potential but not on the biofilm potential. Biofilm viability showed an inverse and respiration-dependent profile when respiring with only the anode or azo dye and was enhanced when respiring with both simultaneously. These results provide new insights into the bacterial respiration strategies in environments containing multiple electron acceptors and support an electron-hopping mechanism within Shewanella electrode-respiring biofilms.

Electrochemical and sonoelectrochemical processes applied to amaranth dye degradation

Amaranth dye is an organic compound largely used in the food and beverage industries with potential toxicity effects on humans. It can be found as a pollutant species in aquatic environments and has been classified as an endocrine disruptor. This study describes amaranth degradation upon ultrasonication associated with an electrochemical system that uses a boron-doped diamond anode BDD, defined as a sonoelectrochemical process. Ninety-minute electrolyses were performed using current densities in the 10-50 mA cm(-2) range, and the concentration decay, pH, energy and current efficiencies, as well as the discoloration rate were evaluated. The amaranth concentration decayed as a function of electrolysis time and the reactions obeyed pseudo first-order kinetics, with an apparent constant rate between 10(-1) and 10(-3)min(-1). The electrochemical and sonoelectrochemical processes at 35 mA cm(-2) yielded TOC removal values between 92.1% and 95.1% respectively, after 90 min. Current efficiency values obtained for both processes were 18.2% and 23.6%. Exhaustive 5h electrolysis was performed and the degradation products were identified by HPLC-MS. A mechanism for the degradation of amaranth was proposed based on an analysis of the aromatic and aliphatic intermediates.

Targeting proteins with toxic azo dyes: a microcalorimetric characterization of the interaction of the food colorant amaranth with serum proteins

The interaction of amaranth with two homologous serum albumins from human and bovine (HSA and BSA) was studied by microcalorimetry. The binding stoichiometry for the complexation of amaranth to both BSA and HSA was around 1, and the equilibrium constants were (5.79 ± 0.07) × 10(5) and (1.76 ± 0.05) × 10(5) M(-1), respectively. The binding reaction to HSA at 298.15 K was driven by a large negative enthalpic contribution and a small but positive entropic contribution, while to BSA, it was entirely enthalpy-driven and the entropic contribution was unfavorable. Parsing of the standard molar Gibbs energy revealed that the complexation was dominated by non-polyelectrolytic forces. Temperature-dependent isothermal titration calorimetry studies revealed that the enthalpic contribution increased and the entropic contribution decreased with the rise in the temperature but the Gibbs energy change remained almost unaltered. Differential scanning calorimetry results revealed that the binding reaction stabilized the serum albumins significantly against thermal unfolding.

Fe₃O₄@rGO doped molecularly imprinted polymer membrane based on magnetic field directed self-assembly for the determination of amaranth

Based on magnetic field directed self-assembly (MDSA) of Fe3O4@rGO composites, a novel magnetic molecularly imprinted electrochemical sensor (MIES) was fabricated and developed for the determination of the azo dye amaranth. Fe3O4@rGO composites were obtained by a one-step approach involving the initial intercalating of iron ions between the graphene oxide layers via the electrostatic interaction, followed by the reduction with hydrazine hydrate to deposit Fe3O4 nanoparticles onto the reduced oxide graphene nanosheets. In molecular imprinting, the complex including the function monomer of aniline, the template of amaranth and Fe3O4@rGO was pre-assembled through π-π stacking and hydrogen bonding interactions, and then was self-assembled on the surface of magnetic glassy carbon electrode (MGCE) with the help of magnetic field induction before electropolymerization. The structures and morphologies of Fe3O4@rGO and the doped molecularly imprinted polymers (MIPs) were investigated by Fourier transform infrared spectrometer (FT-IR), Raman spectra and scanning electron microscope (SEM). Besides, the characterization by differential pulse voltammetry (DPV) showed that Fe3O4@rGO composites promoted the electrical conductivity of the imprinted sensors when doped into the MIPs. The adsorption isotherms and adsorption kinetics were employed to evaluate the performances of MIES. The detection of amaranth was achieved via the redox probe K3[Fe(CN)6] by blocking the imprinted cavities, which avoided the interferences of oxidation products and analogs of amaranth. Furthermore, the prepared MIES exhibited good sensitivity, selectivity, reproducibility and efficiency for detecting amaranth in fruit drinks. The average recoveries were 93.15-100.81% with the RSD <3.0%.

Removal of anionic azo dyes from aqueous solution by functional ionic liquid cross-linked polymer

A novel functional ionic liquid based cross-linked polymer (PDVB-IL) was synthesized from 1-aminoethyl-3-vinylimidazolium chloride and divinylbenzene for use as an adsorbent. The physicochemical properties of PDVB-IL were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The adsorptive capacity was investigated using anionic azo dyes of orange II, sunset yellow FCF, and amaranth as adsorbates. The maximum adsorption capacity could reach 925.09, 734.62, and 547.17 mg/g for orange II, sunset yellow FCF and amaranth at 25°C, respectively, which are much better than most of the other adsorbents reported earlier. The effect of pH value was investigated in the range of 1-8. The result shows that a low pH value is found to favor the adsorption of those anionic azo dyes. The adsorption kinetics and isotherms are well fitted by a pseudo second-order model and Langmuir model, respectively. The adsorption process is found to be dominated by physisorption. The introduction of functional ionic liquid moieties into cross-linked poly(divinylbenzene) polymer constitutes a new and efficient kind of adsorbent.

Comprehensive review and compilation of treatment for azo dyes using microbial fuel cells

Microbial fuel cells (MFCs) represent an emerging technology that focuses on power generation and effluent treatment. This review compiles articles related to MFCs using azo dye as the substrate. The significance of the general components in MFCs and systems of MFCs treating azo dye is depicted in this review. In addition, degradation of azo dyes such as Congo red, methyl orange, active brilliant red X-3B, amaranth, reactive blue 221, and acid orange 7 in MFCs are summarized. Further exploration and operational modification are suggested to address the challenges of complete removal of azo dye with maximum power generation in an MFC. In addition, a sequential treatment system with MFCs is suggested for complete mineralization of azo dye.

Dual electrodes degradation of Amaranth using a thin-film photocatalytic reactor with dual slant-placed electrodes

A dual slant-placed electrodes thin-film photocatalytic (PC) reactor was proposed and successfully applied to degrade Amaranth. In this PC reactor, both the TiO2/Ti photoanode and the Cu cathode are slant-placed in the reaction chamber, and aqueous thin-film formed on the surface of both electrodes as wastewater flowed over them. The degradation efficiency was significantly improved as a result of additional degradation at the cathode. When the TiO2 photocatalyst was irradiated with UV light, photogenerated electrons were spontaneously transferred from the anode to the cathode, driven by the electric field self-generated between the TiO2/Ti anode and the Cu cathode, based on the principle of establishing a Schottky barrier. On the Cu cathode surface, the transferred photoelectrons either reacted with dissolved oxygen to form H2O2, which then oxidized the dye, resulting in indirect oxidation decolourization, or reacted with the dye, resulting in direct reduction decolourization. The colour removal efficiency of the cathode was about half that of the photoanode. These processes together with direct oxidation of the photogenerated holes on the photoanode gave dual electrode degradation of the dye, and the degradation efficiency was significantly improved.

Zeolite Y encapsulated with Fe-TiO2 for ultrasound-assisted degradation of amaranth dye in water

A new heterogeneous catalyst for sonocatalytic degradation of amaranth dye in water was synthesized by introducing titania into the pores of zeolite (NaY) through ion exchange method while Fe (III) was immobilized on the encapsulated titanium via impregnation method. XRD results could not detect any peaks for titanium oxide or Fe(2)O(3) due to its low loading. The UV-vis analysis proved a blue shift toward shorter wavelength after the loading of Ti into NaY while a red shift was detected after the loading of Fe into the encapsulated titanium. Different reaction variables such as TiO(2) content, amount of Fe, pH values, amount of hydrogen peroxide, catalyst loading and the initial dye concentration were studied to estimate their effect on the decolorization efficiency of amaranth. The maximum decolorization efficiency achieved was 97.5% at a solution pH of 2.5, catalyst dosage of 2 g/L, 20 mmol/100 mL of H(2)O(2) and initial dye concentration of 10 mg/L. The new heterogeneous catalyst Fe/Ti-NaY was a promising catalyst for this reaction and showed minimum Fe leaching at the end of the reaction.

Evaluation of potential genotoxicity of five food dyes using the somatic mutation and recombination test

In this study, different concentrations of five food dyes (amaranth, patent blue, carminic acid, indigotine and erythrosine) have been evaluated for genotoxicity in the Somatic Mutation and Recombination Test (SMART) of Drosophila melanogaster. Standard cross was used in the experiment. Larvae including two linked recessive wing hair mutations were chronically fed at different concentrations of the test compounds in standard Drosophila Instant Medium. Feeding ended with pupation of the surviving larvae. Wings of the emerging adult flies were scored for the presence of spots of mutant cells which can result from either somatic mutation or somatic recombination. For the evaluation of genotoxic effects, the frequencies of spots per wing in the treated series were compared to the control group, which was distilled water. The present study shows that carminic acid and indigotine demonstrated negative results while erythrosine demonstrated inconclusive results. In addition 25 mg mL(-1) concentration of patent blue and 12.5, 25 and 50 mg mL(-1) concentrations of amaranth demonstrated positive results in the SMART.

The role of hydrothermally prepared supported photocatalytic composite in organic micro-pollutants removal from the water

This work deals with the non-biodegradable micro-pollutants degradation by supported photocatalyst based heterogeneous photocatalytic reaction. TiO2 based supported photocatalyst was prepared by the hydrothermal technique to improve the photocatalytic performance along with easy recovery of suspended photocatalyst from aqueous medium after photoreaction. TO2 deposited calcium alumino-silicate beads (CASB) supports were prepared under mild hydrothermal conditions (Temparature-200 degrees C, Duration-24 h). In the present study, industrial dyes such as Amaranth and Brilliant Yellow were used as model micro-pollutants in aqueous solution. A real time pesticide industrial effluent was tested for its photocatalytic removal of organic pollutants using TO2 deposited CASB supported photocatalytic composite as an effective photocatalyst. Photocatalytic degradation of micro-pollutants present in aqueous medium was carried out in a batch photoreactor, at atmospheric pressure and temperature (28 degrees C). The influence of different light sources, irradiation time, catalyst load and catalytic performance is discussed. The photocatalytic degradation of micro-pollutants in aqueous medium was evaluated by determination of COD and %T. Easy separation and recovery of suspended photocatalysts from aqueous solution is the major advantage of hydrothermally prepared supported photocatalytic composite.

Kinetics of ozone-initiated oxidation of textile dye, Amaranth in aqueous systems

The ozone facilitated oxidation mechanism of water soluble azo anionic dye, amaranth (Am) was investigated monitoring the depletion kinetics of the dye spectrometrically at 521 nm. The oxidation kinetics of the dye by ozone was studied under semi-batch conditions, by bubbling ozone enriched oxygen through the aqueous reaction mixture of dye, as function of flow rate, ionic strength, [O(3)] and pH variations. With excess concentration of ozone and other reagents and low [amaranth], reaction followed pseudo-first-order kinetics with respect to the dye. Added neutral salts had marginal effect on the reaction rate and the variation of pH from 7 to 2 and 7 to 12 exerted only small increases in the reaction rate suggesting molecular ozone possibly is the principle reactive species in oxidation of dye. The reaction order with respect ozone was near unity and it varied slightly with pH and flow rate variations. The overall second-order rate constant for the reaction was (105 ± 4) M(-1) min(-1). The main oxidation products immediately after amaranth decolorization were identified. The reaction mechanism and overall rate law were proposed. After spiking the seawater, river water and wastewaters with Amaranth dye, the reaction rates and trends in BOD and COD under control and natural conditions were investigated. The rate of depletion of the dye in natural waters was relatively lower, but the ozonation process significantly decreased both the BOD and COD levels.

Fast removal and recovery of amaranth by modified iron oxide magnetic nanoparticles

The adsorption and removal of amaranth (AM) from an aqueous solution by iron oxide nanoparticles (IONPs) coated with cetyltrimethylammonium bromide (CTAB) as adsorbent was reported. The novel magnetic separation was quite efficient for the adsorption and desorption of AM. In an aqueous solution of AM at 25 degrees C, the adsorption data could be fitted by the Langmuir equation with a maximum adsorption amount of 1.05 mg mg(-1) and a Langmuir adsorption equilibrium constant of 0.90 Lmg(-1). The effect of temperature, pH of aqueous medium, electrolyte concentration, composition of desorbent solvent and interfering ions on the recovery process were also investigated. Methanol was used for desorption of adsorbed AM. Due to the absence of internal diffusion resistance both adsorption and desorption of AM were fast and could be completed within 5 min. The results indicated that the CTAB-coated IONPs could be employed in the removal of the anionic dye from wastewater. The AM was removed successfully in spiked samples of Karoon River water.

Preparation and characterization of an anionic dye-polycation molecular films by electrostatic layer-by-layer adsorption process

This communication reports the formation and characterization of self-assembled films of a low molecular weight anionic dye amaranth and polycation poly(allylamine hydrochloride) (PAH) by electrostatic alternating layer-by-layer (LBL) adsorption. It was observed that there was almost no material loss occurred during adsorption process. The UV-vis absorption and fluorescence spectra of amaranth solution reveal that with the increase in amaranth concentration in solution, the aggregated species starts to dominate over the monomeric species. New aggregated band at 600 nm was observed in amaranth-PAH mixture solution absorption spectrum. A new broad low intense band at the longer wavelength region, in the amaranth-PAH mixture solution fluorescence spectrum was observed due to the closer association of amaranth molecule while tagged into the polymer backbone of PAH and consequent formation of aggregates. The broad band system in the 650-750 nm region in the fluorescence spectra of different layered LBL films changes in intensity distribution among various bands within itself, with changing layer number and at 10 bilayer LBL films the longer wavelength band at 710 nm becomes prominent. Existence of dimeric or higher order n-meric species in the LBL films was confirmed by excitation spectroscopic studies. Almost 45 min was required to complete the interaction between amaranth and PAH molecules in the one-bilayer LBL film.

Investigation of the toxicity of the products of decoloration of Amaranth by Trametes versicolor

Trametes versicolor decolorized 2000 mg L(-1) of the mono-azo substituted naphthalenic dye Amaranth with no dye sorption observed visually. The changes in the toxicity were assessed over a period of 30 d for the dye-treated viable culture, control (no dye added), and a boiled culture treated with dye, using the Microtox Acute Toxicity assay. Before dye addition, the culture filtrate had some toxicity, which increased after the dye addition. The toxicity of the dye-treated culture decreased during the treatment. The loss of toxicity occurred at the same time, with the loss of color suggesting that detoxification is associated with decoloration. The change in pH was due to natural metabolic processes and had a small effect on detoxification. Because the toxicity of the treatment was similar to that of the control at the end of the treatment, the effluent seems to be safe for release into the environment, potentially rendering this treatment suitable for industrial application.

Asymmetric membrane capsule for osmotic delivery of flurbiprofen

An asymmetric membrane capsule of cellulose acetate for osmotic delivery of flurbiprofen has been developed and influence of osmogents and solubilizing agent on in vitro drug release were evaluated. The capsule membrane was prepared by the phase inversion technique. To ensure the osmotic delivery of drug, two approaches were adopted: (i) the drug was encapsulated with osmogents like sodium chloride and mannitol to increase the osmotic pressure of the core, and (ii) the drug was encapsulated with sodium lauryl sulfate in the core of the formulation to increase the solubility and thus its osmotic pressure. Scanning electron microscopy of the membrane confirmed its porous, dense asymmetric nature. Dye test revealed in situ pore formation. The in vitro release study showed that as the proportion of osmogent and solubilizing agent was increased the release rate also increased. A good correlation was observed between the zero-order rate constant and the amount of the osmogent and solubilizing agent used.

Reduction and partial degradation mechanisms of naphthylaminesulfonic azo dye amaranth by Shewanella decolorationis S12

Reduction and biodegradation mechanisms of naphthylaminesulfonic azo dye amaranth using a newly isolated Shewanella decolorationis strain S12 were investigated. Under anaerobic conditions, amaranth was reduced by strain S12, and a stoichiometric amount of two reduction products RP-1 and RP-2 were generated. UV/visible spectrophotometric and high performance liquid chromatography (HPLC) analysis indicated that RP-1 and RP-2 were 1-aminenaphthylene -4-sulfonic acid and 1-aminenaphthylene-2-hydroxy-3, 6-disulfonic acid. The result strongly supports a mechanism of azo dye reduction by the process via the reductive cleavage of the azo bond to form corresponding aromatic amines. The result of HPLC analyses revealed that these aromatic amines were not able to be mineralized by strain S12 under anaerobic conditions. But after re-aeration of the decolorized culture, RP-2 was mineralized completely by this microorganism, but the consumption of RP-1 was not observed. Ames test showed that amaranth had mutagenic but no cytotoxic potential. The mutagenic potential was relieved after the anaerobic treatment with strain S12 as the mutagenic effect of the two reduction products from amaranth was not detected by Ames test. Thus, the ability of strain S12 to reduce and partially mineralize the naphthylaminesulfonic azo dye efficiently was demonstrated, which can potentially be used to biodegrade and detoxify wastewater containing azo dyes using an alternating anaerobic/aerobic treatment procedure.

Electrochemical degradation of amaranth aqueous solution on ACF

The degradation of Amaranth, a kind of azo dye, has been studied under galvanostatic model with activated carbon fiber (ACF) electrode in aqueous solution with electrochemical method. The ACF was used as anode and cathode, respectively for the decolorization process. The onset oxidation potential and reduction potential for Amaranth on ACF were respectively ascertained at 0.6 and -0.4 V. During the range of -1.1 to 0.50 mA cm(-2), the decolorization was clarified into three processes as electroreduction, adsorption and electrooxidation. There were little contributions to the color and COD removals for the process of adsorption. The color removal can be up to 99% when the current density was 0.50 mA cm(-2). The maximum COD removal was 52% for the process of electrooxidation. Hundred percent color removal was obtained when the current density of -1.0 mA cm(-2) was applied. The maximum COD removal was 62% for the electroreduction. The COD removal results from the adsorption of products for the decolorization process of electrooxidation or electroreduction.

Effects of sterilizing-grade filters on the physico-chemical properties of onion-like vesicles

Spherulites are new promising multilamellar vesicles that we study in a drug delivery context. The sterilization of spherulites suspensions is a necessary step before biological tests and later, before pharmaceutical applications (for example, parenteral or local injections). Among all sterilizing operations, the filtration through 0.22 microm sterilizing-grade filters (of the type Millex (Ø 4 mm) by Millipore) is easy and rapid, and we decided to study it as a mean to obtain sterile suspensions. The spherulites diameter is usually comprised between 0.2 and 0.5 microm but bigger vesicles occur and reach Ø 1 microm. The effects of such filters on vesicles' size and lipids' concentration were then compromised. After examination of this challenging operation, results proved that the sterilizing filtration had no effect on these two parameters whatever the formulation chosen. Then, the possible release of amaranth, an encapsulated hydrophilic dye was followed. With the formulations and in spite of a filter diameter inferior to that of the vesicles, the encapsulation yields were not significantly different before and after the filtration and no leakage could be detected. Finally, the spherulites' functionality after sterilizing filtration was studied under the chemical angle: vesicles containing an amphiphilic reactive anchor (CholE3ONH2) were still able to bind covalently a peptidic molecular recognition pattern. The ligation was quantified by fluorimetry as high as for non-filtrated suspensions. Thus, though spherulites can present a diameter superior to that of the sterilizing filters, their passage through them do not alter the physico-chemical properties of these vesicles.

Semiconductor-mediated photocatalysed degradation of two selected azo dye derivatives, amaranth and bismarck brown in aqueous suspension

Semiconductor-mediated photocatalysed degradation of two selected azo dye derivatives such as amaranth (1) and bismarck brown (2) has been investigated in aqueous suspension by monitoring the change in substrate concentration employing UV spectroscopic analysis technique as a function of irradiation time. The degradation was studied under different conditions such as types of TiO(2), pH, substrate concentration, catalyst concentration, and in the presence of electron acceptors such as hydrogen peroxide (H(2)O(2)), potassium bromate (KBrO(3)) and ammonium persulphate (NH(4))(2)S(2)O(8) besides air. The degradation rates were found to be strongly influenced by all the above parameters. The photocatalyst Degussa P25 showed comparatively highest photocatalytic activity. The dye derivative, bismarck brown (2) was found to degrade faster than amaranth dye (1).

A square-wave adsorptive stripping voltammetric method for the determination of Amaranth, a food additive dye

Square-wave adsorptive stripping voltammetric (AdSV) determinations of trace concentrations of the azo coloring agent Amaranth are described. The analytical methodology used was based on the adsorptive preconcentration of the dye on the hanging mercury drop electrode, followed by initiation of a negative sweep. In a pH 10 carbonate supporting electrolyte, Amaranth gave a well-defined and sensitive AdSV peak at -518 mV. The electroanalytical determination of this azo dye was found to be optimal in carbonate buffer (pH 10) under the following experimental conditions: accumulation time, 120 s; accumulation potential, 0.0 V; scan rate, 600 mV/s; pulse amplitude, 90 mV; and frequency, 50 Hz. Under these optimized conditions the AdSV peak current was proportional over the concentration range 1 x 10(-8)-1.1 x 10(-7) mol/L (r = 0.999) with a detection limit of 1.7 x 10(-9) mol/L (1.03 ppb). This analytical approach possessed enhanced sensitivity, compared with conventional liquid chromatography or spectrophotometry and it was simple and fast. The precision of the method, expressed as the relative standard deviation, was 0.23%, whereas the accuracy, expressed as the mean recovery, was 104%. Possible interferences by several substances usually present as food additive azo dyes (E110, E102), gelatin, natural and artificial sweeteners, preservatives, and antioxidants were also investigated. The developed electroanalyticals method was applied to the determination of Amaranth in soft drink samples, and the results were compared with those obtained by a reference spectrophotometric method. Statistical analysis (paired t-test) of these data showed that the results of the 2 methods compared favorably.

Kinetic Spectrophotometric Determination of Rutin by Its Inhibitory Effect on the Oxidation of Amaranth by Potassium Periodate

A novel kinetic spectrophotometric method is described for the determination of rutin. The method is based on the inhibitory effect of rutin on the oxidation reaction of amaranth by potassium periodate in acidic media at 100 degrees C. The linear range for the determination of rutin is 0.02 - 0.50 microg/ml, and the detection limit is 0.014 microg/ml. The method has been successfully applied to the determination of rutin in medicine of rutin tablet and traditional Chinese medicine.

Influence of the composition of in-vitro azo-reducing systems on the degradation kinetics of the model compound amaranth

The purpose of this study was to investigate the influence of the composition of in-vitro azo-reducing systems on the degradation kinetics of the model compound amaranth. The degradation kinetics of amaranth were determined under anaerobic conditions both in rat caecal content (ex-vivo) and in a variety of in-vitro degradation media derived from rat caecal content. It was observed that the reducing activity was highly dependent on the preparation method and composition of the degradation medium. In pure rat caecal content, the degradation of amaranth was apparent first order (k = 0.044 +/- 0.002 min(-1)), while dilution of the rat caecal content resulted in an apparent zero-order degradation. Both apparent zero- and first-order degradations were also observed in media made up of diluted rat caecal content to which cofactors such as NADP, D-glucose-6-phosphate, glucose-6-phosphate dehydrogenase and Bz were added. This study demonstrates that in-vitro azo-reducing kinetics are dependent on the composition and mode of preparation of the in-vitro media used. This has to be taken into account when evaluating the degradability of azo-aromatic drug delivery systems in-vitro.

Solution structure of the main alpha-amylase inhibitor from amaranth seeds

The most abundant alpha-amylase inhibitor (AAI) present in the seeds of Amaranthus hypochondriacus, a variety of the Mexican crop plant amaranth, is the smallest polypeptide (32 residues) known to inhibit alpha-amylase activity of insect larvae while leaving that of mammals unaffected. In solution, 1H NMR reveals that AAI isolated from amaranth seeds adopts a major trans (70%) and minor cis (30%) conformation, resulting from slow cis-trans isomerization of the Val15-Pro16 peptide bond. Both solution structures have been determined using 2D 1H-NMR spectroscopy and XPLOR followed by restrained energy refinement in the consistent-valence force field. For the major isomer, a total of 563 distance restraints, including 55 medium-range and 173 long-range ones, were available from the NOESY spectra. This rather large number of constraints from a protein of such a small size results from a compact fold, imposed through three disulfide bridges arranged in a cysteine-knot motif. The structure of the minor cis isomer has also been determined using a smaller constraint set. It reveals a different backbone conformation in the Pro10-Pro20 segment, while preserving the overall global fold. The energy-refined ensemble of the major isomer, consisting of 20 low-energy conformers with an average backbone rmsd of 0.29 +/- 0.19 A and no violations larger than 0.4 A, represents a considerable improvement in precision over a previously reported and independently performed calculation on AAI obtained through solid-phase synthesis, which was determined with only half the number of medium-range and long-range restraints reported here, and featured the trans isomer only. The resulting differences in ensemble precision have been quantified locally and globally, indicating that, for regions of the backbone and a good fraction of the side chains, the conformation is better defined in the new solution structure. Structural comparison of the solution structure with the X-ray structure of the inhibitor when bound to its alpha-amylase target in Tenebrio molitor shows that the backbone conformation is only slightly adjusted on complexation, while that of the side chains involved in protein-protein contacts is similar to those present in solution. Therefore, the overall conformation of AAI appears to be predisposed to binding to its target alpha-amylase, confirming the view that it acts as a lid on top of the alpha-amylase active site.

Structural determination of unknown subsidiary colors in commercial food red Nos. 2 and 102

Major subsidiary colors A (Sub A) and B (Sub B) in commercial Food Red No. 102, and colors C (Sub C) and D (Sub D) in commercial Food Red No.2 were isolated. These structures were characterized by physicochemical evidence. The structures of Sub A, B, and C are trisodium salt of 7-hydroxy-8-(6-sulfonaphthyl-2-azo)-1,3-naphthalenedisulfonic++ + acid, disodium salt of 4-amino-3-(4-sulfonaphthyl-1-azo)-1-naphthalenesulfonic acid and trisodium salt of 3-hydroxy-4-(6-sulfonaphthyl-2-azo)-2,7-naphthalenedisulfonic++ + acid, respectively. Sub D was identified as Sub B.

Microbiological, nutritional and sensory aspects of stored amaranth biscuits and amaranth crackers

The object of this work was to present some results from the evaluation of microbiological (total bacterial count, coliform bacteria, aerobic sporogenic bacteria, yeasts and moulds), nutritional (lysine) and sensory (shape, surface, colour, consistency, odour, taste, the profiling of tastiness) quality and of the a(w) values of amaranth biscuits and crackers during the four-month storage (January-April, 1996 every 30th day) in laboratory conditions (20 +/- 2 degrees C and RH = 62 +/- 1%). From the aspect of consumers the chosen parameters of quality permitted the storage stability of the indicated non-traditional products to be estimated and on the basis of the favourable evaluation recommended for the rational nutrition.

A pitfall in determining the globulin/albumin ratio in amaranth grains

In amaranth grains (Amaranthus hypochondriacus L. and Amaranthus cruentus L.), there were two albumin (Alb) fractions, Alb-1 and Alb-2; Alb-1 was extracted with water or 0.5 M NaCl, and Alb-2 was extracted with water after extracting Alb-1 and globulin. The amount of Alb-2 comprised about 30% of the total albumin and globulin content. Little or no measurable protein corresponding to the amaranth Alb-2 was extracted from seeds of buckwheat (Fagopyrum esculentum Moench), quinoa (Chenopodium quinoa L.), or barley (Hordeum vulgare L. cv Sekitorisai-1). That the globulin/albumin ratio (G/A) in amaranth grains has been conflicting among investigators probably accounts for the consideration of Alb-2 during extraction. We here report the revised G/A ratio of 0.3-0.4.