Progress and prospects of Mg-based amorphous alloys in azo dye wastewater treatment

Mg-based amorphous alloys exhibit efficient catalytic performance and excellent biocompatibility with a promising application probability,specifically in the field of azo dye wastewater degradation.However,the problems like difficulty in preparation and poor cycling stability need to be solved.At present,Mg-based amorphous alloys applied in wastewater degradation are available in powder and ribbon.The amorphous alloy powder fabricated by ball milling has a high specific surface area,and its reactivity is thousands of times better than that of gas atomized alloy powder.But the development is limited due to the high energy consumption,difficult and costly process of powder recycling.The single roller melt-spinning method is a new manufacturing process of amorphous alloy ribbon.Compared to amorphous powder,the specific surface area of amorphous ribbon is relatively lower,therefore,it is necessary to carry out surface modification to enhance it.Dealloying is a way that can form a pore structure on the surface of the amorphous alloys,increasing the specific surface area and providing more reactive sites,which all contribute to the catalytic performance.Exploring the optimal conditions for Mg-based amorphous alloys in wastewater degradation by adjusting amorphous alloy composition,choosing suitable method to preparation and surface modification,reducing cost,expanding the pH range will advance the steps to put Mg-based amorphous alloys in industrial environments into practice.

Bioremediation of Textile Azo Dyes Amido Black 10B, Reactive Black 5, Reactive Blue 160 by Lentinus squarrosulus AF5 and Assessment of Toxicity of the Degraded Metabolites

Bioremediation is an eco-compatible and economical approach to counter textile dye menace. The isolated Lentinus squarrosulus AF5 was assessed for decolourization of textile azo dyes, and had shown ~93%, 88% and 70% decolorization of Reactive blue 160 (RB160), Reactive black 5 (RB5) and Amido black 10B (AB10B) respectively. Further analysis using UV-vis, HPLC, and FTIR, 1H NMR had shown the degradation of the dyes. Toxicity analysis of the metabolites was performed using seed germination and plant growth on two agriculturally important plants Guar (Cyamopsis tetragonoloba) and wheat (Triticum aestivum) as well as cytotoxicity analysis using the human keratinocyte cell line (HaCaT). The dye mix appeared inhibitory for seed germination (20% - 40%), whereas metabolites were non-inhibitory for germination. Treatment of HaCaT cells with of dye mix and metabolites led into 45% and ~100% of cell viability of HaCaT cells respectively. Therefore, metabolites following degradation of the dye mix were observed to be non-toxic.

Adsorption behavior of Azo Dye C. I. Acid Red 14 in aqueous solution on surface soils

Azo dyes have received considerable attention because of their association with various human health problems. The aim of the investigation is to determine the adsorption behavior ofazo dyes in aqueous solution on DG06, GSE17200, and GSE17201 soils using C. I. Acid Red 14 （AR14） as example. The experimental results indicate that the Freundlich model expresses the adsorption isotherm better than the Langmuir model and the pseudo-second-order model achieves adsorption of AR14 on the three soils well. Based on the pseudo-second-order model, the adsorption thermodynamic of AR14 on DG06 soil have been studied and the thermodynamics parameter of AGO is determined and AGO value shows the adsorption process of AR14 on DG06 is mainly physical in nature. Furthermore, the effects of temperature, pH and salinity （NaC1） on adsorption have been investigated. The decrease in pH or the increase in salinity enhances the adsorption of AR14 by DG06, GSE17200, and GSE17201.

Comparison of decolorization of reactive azo dyes by microorganisms isolated from various sources

Azo dyes are among the oldest man made chemicals and they are still widely used in the textile, printing and the food industries. About 10%-15% of the total dyes used in the industry is released into the environment during the manufacturing and usage. Some dyes and some of their N substituted aromatic bio transformation products are toxic and/or carcinogenic and therefore these dyes are considered to be environmental pollutants and health hazards. These azo dyes are degraded by physico chemical and biological methods. Of these, biological methods are considered to be the most economical and efficient. In this work, attempts were made to degrade these dyes aerobically. The organisms which were efficient in degrading the following azo dyes Red RB, Remazol Red, Remazol Blue, Remazol Violet, Remazol Yellow, Golden Yellow, Remazol Orange, Remazol Black were isolated from three different sources viz., wastewater treatment plant, paper mill effluent treatment plant and tannery wastewater treatment plant. The efficiency of azo dye degradation by mixed cultures from each source was analyzed. It was found that mixed cultures from tannery treatment plant worked efficiently in decolorizing Remazol Red, Remazol Orange, Remazol Blue and Remazol Violet, while mixed cultures from the paper mill effluent worked efficiently in decolorizing Red RB, Golden Yellow and Remazol Yellow. The mixed cultures from wastewater treatment plant efficiently decolorized Remazol Black.

Biodegradation of azo dyes by genetically engineered azoreductase

A azoreductase gene with 537 bp was obtained by PCR amplification from Rhodobacter sphaeroides AS1 1737 The enzyme, with a molecular weight of 18 7 kD, was efficiently expressed in Escherichia coli and its biodegradation characteristics for azo dyes were investigated. Furthermore, the reaction kinetics and mechanism of azo dyes catalyzed by the genetically engineered azoreductase were studied in detail. The presence of a hydrazo-intermediate was identified, which provided a convincing evidence for the assumption that azo dyes were degraded via an incomplete reduction stage.

Quinone-mediated decolorization of sulfonated azo dyes by cells and cell extracts from Sphingomonas xenophaga

The effects of various quinone compounds on the decolorization rates of sulfonated azo dyes by Sphingomonas xenophaga QYY were investigated. The results showed that anthraquinone-2-sulfonate （AQS） was the most effective redox mediator and AQS reduction was the rate-limited step of AQS-mediated decolorization of sulfonated azo dyes. Based on AQS biological toxicity tests, it was assumed that AQS might enter the cells and kill them. In the cytoplasmic extracts from strain QYY, AQS more effectively increased decolorization rates of sulfonated azo dyes than other quinone compounds. In addition, we found a NADH/FMN-dependent AQS reductase using nondenaturing polyacrylamide gel electrophoresis （Native-PAGE）.

Decolorization and bio degradation metabolism of azo dyes by Pseudomonas S-42

A bacterial strain was isolated from activated sludge and has been identified as Pseudomonas sp. S-42 capable of decolorizing azo dyes such as Diamira Brilliant Orange RR (DBO-RR), Direct Brown M (DBM), Eriochrome Brown R (EBR) and so on. The growing cells, intact cells, cell-free extract and purified enzyme of strain S-42 could decolorize azo dyes under similar conditions at the optimum pH 7.0 and temperature of 37℃. The efficiencies of decolorization for DBO-RR, DBM, EBR with intact cells stood more than 90%. When the cell concentration was 15mg (wet)/ml and the reaction time was 5 hours, the decolorizing activities of intact cells for above three azo dyes were 1.75, 2.4, 0.95 μg dye/mg cell, respectively. Cell-free extract and purified enzyme belonged to azoreductase with molecular weight about 34000±2000 and Vmax and Km values for DBO-RR of 13μmol/mg protein/nun and 54μmol, respectively. The results from the detection of the biodegradation products of DBO-RR by spectrophotometric and NaNO2 reaction methods showed that the biodegradation of azo dyes was initiated by the reducing cleavage of azo bonds. The biodegradation metabolism path for DBO-RR by Psued. S-42 was hypothesized.

Study on photodegradation of Azo dye by polyoxometalates/polyvinyl alcohol

A series of photocatalysts, K11[Ln(PW11O39)2]/PVA (Ln=La, Ce, Pr, Nd, Sm) were prepared by K11[Ln(PW11O39)2] (Ln=La, Ce, Pr, Nd, Sm) containing five kinds of lanthanides and polyvinyl alcohol as the support. The catalysts obtained were characterized by Fourier transform infrared spectra, UV-vis spectra, powder X-ray diffraction, and scanning electron microscopy, indicating that the structure of K11[Ln(PW11O39)2] and polyvinyl alcohol remained intact, respectively. The photocatalysts exhibited efficient catalytic activity to degrade methyl orange, Congo Red, Ponceau 2R. The maximal degradation conversions of the three kinds of dyes were 99.58%, 47.61%, 72.42%, respectively.

TiO_2/beads as a photocatalyst for the degradation of X_(3B) azo dye

The feasibility of photocatalytic degradation of X 3B azo dye by TiO 2/beads photocatalyst was studied. The effects of parameters such as the amount of TiO 2/beads, airflow, as well as the concentrations of H 2O 2, Fe 3+ , Mg 2+ and Na + on the photocatalytic degradation of X 3B azo dye were also studied. The results showed that 25 mg/dm 3 X 3B azo dye can be photocatalytically degraded completely by 30 min illumination with a 375W medium pressure mercury lamp. Adding a small amount of H 2O 2 or Fe 3+ , the efficiencies of photocatalytic degradation of X 3B azo dye were increased rapidly. The mechanisms of the reaction and the role of the additives were also investigated. After 120 hours TiO 2/beads showed no significant loss of the photocatalytic activity.

Dyeing of Polyester and Nylon with Semi-synthetic Azo Dye by Chemical Modification of Natural Source Areca Nut

Various azo compounds(Modified dyes)have been synthesised by chemical modification of areca nut extract(epicate-chin),a plant-based Polyphenolic compound to get semi-synthetic dyes.Three different primary amines namely p-nitro aniline,p-anisidine and aniline,were diazotized to form their corresponding diazonium salts which were further coupled with an areca nut extract.Preliminary characterization of the areca nut extract and the resultant azo compounds(Modified dyes)was carried out in terms of melting point,solubility tests,thin layer chromatography,UV-Visible and FTIR spectroscopy.These modified dyes were further applied on polyester and nylon fabrics and%dye exhaustion was evaluated.Dyed fabrics were further tested for their fastness properties such as wash fastness,rubbing fastness,light fastness and sublimation fastness.The results of the fastness tests indicate that,all the three modified dyes have good dyeability for polyester and nylon fabrics.The dyed fabrics were also tested for ultraviolet protection factor which showed very good ultraviolet protection.

Enhancement of modulation depth of an all-optical switch using an azo dye-ethyl red film

The polymethyl methacrylate （PMMA） film doped with an azo dye ethyl-red （ER） film is employed to demonstrate the properties of an all-optical switch by its photoinduced dichroism and birefringence. We show how to enhance remarkably the modulation depth of all-optical switches almost to 100% by using two linear polarization beams： one beam is inclined at 45° with respect to the probing beam and serves as a pumping beam, and the other beam is perpendicular to the probing beam and used as an erasing beam. Furthermore, a maximum-to-minimum output intensity ratio of 2000：1 is achieved in experiment, which is very useful and important for optical storages and image displays.

Degradation of Azo Dyes by Photocatalysis of Fe(Ⅲ)-oxalate Complexes/H_2O_2 in Aqueous Non-ionic Surfactant Triton X-100 Solution

Two azo dyes,C.I.Reactive Red 195(RR195)and C.I.Acid Black 234(AB234)were degraded by photocatalysis of Fe(Ⅲ)-oxalate complexes/H2O2 in aqueous non-ionic surfactant,Triton X-100(TX-100)solution.Some factors affecting the dye degradation such as TX-100 concentration,irradiation intensity,and sodium chloride were investigated.The interaction and competition between dye and TX-100 during the degradation were also examined using spectrophotometry and maximum bubble pressure method,respectively.The results indicated that TX-100 showed a significant reduction effect on degradation of two azo dyes,but which was largely confined to TX-100 concentration below the Critical Micellar Concentration(CMC).And the reduction was considerably decreased above the CMC,especially in the case of AB234.Moreover,the reducing effect of TX-100 on dye degradation almost did not vary with irradiation intensity.And the impact of sodium chloride on dye degradation was limited by the addition of TX-100.

A new inorganic azo dye and its thin film:MoO_4N_4H_6

Thin films of hydrazine molybdenum （MoO4N4H6）, a new inorganic azo dye, were synthesized and deposited on a commercial glass substrate using the chemical bath deposition technique. Subsequently, the optical transmission, reflectivity, absorption, refractive index, and dielectric constant of hydrazine molybdenum were investigated using an ultraviolet-visible spectrophotometer. In addition, the film structure was analyzed by mid-infrared spectroscopy. The spectra of the films were found to be in line with those in the literature. The surface properties of all films were examined using a computer-controlled digital scanning electron microscope with a secondary electron detector. The areas of application and the technological advantages of this material were also considered.

Effect of Quinoid Mediators on the Decolorization of Azo Dyes by the Strain CD-2

In the present study, the effects of various quinone compounds on the decolorization rates of azo dyes by the E. coli strain CD-2 were investigated. The results showed that Lawsone was the most effective redox mediator. The optimum concentration for Lawsone is 0.1 mmol/L. The effects of physic-chemical parameters on the Methyl Orange degradation by the strain were determined. The results indicated that, in the quinone mediated decolorization system, strain CD-2 exhibited a good degradation ability in the range of pH from 4 to 9, temperature from 20°C to 50°C and salinity from 1% to 6%. With Lawsone as a redox mediator, a broad spectrum of azo dyes with different structures could be decolorized by the strain. All the results showed that the addition of a redox mediator can be valuable for treating dye-colored wastewaters.

Research on Some Brown Iron Complex Azo Dyes

Some novel 1:1 and 1 ：2 Fe complex azo dyes were synthesized in this study.The mass spectrum analysis of 1:1 and 1:2 Fe complex azo dyes is presented.Lightfastness,rubbing fastness and washing fastness of these metallized complex dyes were evaluated for use on wool.Results show that these dyes are of good lightfastness and satisfactory brown shades.

STUDY ON ENRICHMENT AND SEPARATION OF TRACE ELEMENTS WITH SILICA GELS MODIFIED BY HETEROCYCLIC AZO DYES

Two types of modified silica gels were prepared by adsorption method and bonding method respectively. Enrichment and separation of trace metal ions have been done by using the column packed with modified silica gels.

Azo Dye Decolorizing by Candida Lipolytica Using Response Surface Methodology

Candida lipolytica with efficient decolorization of Acid Red3 G was screened. An experimental design based on the response surface method was applied to finding the optimal conditions. The results showed that the optimum dye decolorizing conditions were160 r/min with shake cultivation,initial dye concentration( 400 mg/L),incubation temperature 30 ℃ with inoculum amount 5%,and the medium compositions were glucose 21 g/L,yeast extract 10 g/L,Mg^(2+)20 mmol/L,and Cu^(2+)9. 5 mg/L. The Candida lipolytica culture exhibited decolorization 97. 5% within 48 h. These results demonstrated that the Candida lipolytica culture had high potential to decolorize azo dyes textile-dyeing wastewater.

Screening and Identification of a Highly Effective Azo Dye-degrading Strain

In this study, strain tsl-2, which could effectively degrade azo dye amaranth, was isolated from activated sludge in the sewage treatment pool of a print- ing and dyeing mill in Liaocheng City, Shandong Province. Based on morphological characteristics, physiological and biochemical properties and 16S rDNA se- quence analysis, the isolated strain was identified preliminarily as Leucobacter komagatae. The decolorization of strain tsl-2 was investigated under static culture conditions. The results showed that strain tsl-2 exhibited the highest decolorization rate when initial concentration of amaranth was 50 rag/L, and the maximum de- colorization concentration was 1 250 mg/L. After decolorization under optimal conditions for 14 h, the decolorization rate of amaranth reached above 95%. This study provided the basis for further optimization of azoreductase production conditions.

Biocoagulation of Direct Red-31 and Direct Yellow-12 Azo Dyes from Synthetic Wastew ater with Moringa Oleifera Seed Presscake

Batches experiments were carried out to study the removal potentials of Moringa oleifera seed presscake( MOSP),the residual solids of Moringa oleifera seed after oil extraction used as a natural coagulant for the removal of two direct azo dyes including Direct Red-31( DR-31) and Direct Yellow-12( DY-12). The results indicated that the MOSP contained active proteins which were active agents and efficient for the removal of the two dyes. Higher temperature and lower p H were favorable for dye removal. The removal rates of the two dyes increased with the increasing MOSP dosage. Inorganic salts improved the dye removal efficiencies by the salt-in effect that prompted the release of proteins from the MOSP particles. Suspended solid simulated by kaolin decreased the dye removal efficiencies because of the competition for active sites of the MOSP between the kaolin particles and the dye molecules. The most likely mechanism for the removal of the two dyes by using MOSP as coagulant was a combined effect of adsorption and neutralisation of charges and the nucleation of the MOSP particles. The results provide new insight into the MOSP utilization and development of new coagulant for dye removal.

Azo dye degradation behavior of AlFeMnTiM(M = Cr, Co, Ni) high-entropy alloys

Because of the potential carcinogenic effects and difficult degradation of azo dyes, their degradation has been a longstanding problem. The degradation of azo dye Direct Blue 6(DB6) using ball-milled(BM) high-entropy alloy(HEA) powders was characterized in this work. Newly designed AlFeMnTiM(M = Cr, Co, Ni) HEAs synthesized by mechanical alloying(MA) showed excellent performance in the degradation of azo dye DB6. The degradation efficiency of AlFeMnTiCr is approximately 19 times greater than that of the widely used commercial Fe–Si–B amorphous alloy ribbons and more than 100 times greater than that of the widely used commercial zero-valent iron(ZVI) powders. The galvanic-cell effect and the unique crystal structure are responsible for the good degradation performance of the BM HEAs. This study indicates that BM HEAs are attractive, valuable, and promising environmental catalysts for wastewater contaminated by azo dyes.