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The pyrazole derivatives and its metal complexes are considered to be pharmacologically significant with a variety of pharmacological applications. The present investigation highlights the synthesis of pyrazole based novel ligand, 4-[(E)-(3-hydroxypyridin-2-yl)diazenyl]-5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one (PDP) and its Co(II), Ni(II), Cu(II) complexes. The structure of the synthesized compounds has been evaluated using various physicochemical and spectroscopic techniques. Cyclic Voltammetry (CV) results are used to confirm the electrocatalytic ability of the modified electrode, [Co(PDP)2]Cl2.2H2O/GCE for the detection of Folic acid (FA) at different concentrations. The CV results displayed good electro-catalytic activity with 10-120 µML-1 with limits of detection (LOD) of 0.0666 µML-1. This electrode has a sensitivity of 2.8784 µAµM-1cm-2 for FA. The bio-efficacy of the synthesized ligand and its complexes have been evaluated against the bacteria (S.aures and E.coli) and fungal (A.flavus and P.anomala) strains using standard method. Antidiabetic study on two different enzymes, a-amylase and a-Glucosidase indicating excellent inhibition by the metal complexes having the maximum IC50 Value of 105.34 for a-amylase and 107.15 mg/mL for a-Glucosidase. [ABSTRACT FROM AUTHOR]

This study presents the development of ultra‐thin azo‐dye polarizers, notable for their minimal thickness (100‐200 nm) and superior optical performance, with polarization efficiency exceeding 99.9%, extinction ratios above 4000, transmittance over 45.3%, and dichoric ratio over 100. Utilizing cost‐effective solution‐processing methods, we fabricate these high‐performance polarizers and determine optimal experimental conditions for peak efficacy. Our research includes comprehensive Scanning Electron Microscopy analyses to understand the microstructural properties of these azo‐dye thin film polarizers, contributing significantly to the field of advanced display technologies. [ABSTRACT FROM AUTHOR]

Vertically Aligned LCD is one of the most widely used optical modes in LCD TV and mobile devices. It is also a very important category of passive LC displays used in Automobiles. It has the advantages of perfect dark state and very high contrast ratio for normal viewing. However, single domain VA LCD has the intrinsic issue of dead zone (contrast vanishing zone) in certain viewing direction in the voltage‐on state, which seriously limits its viewing angle performance. Recently, the State Key Laboratory on Advanced Displays and Optoelectronics Technologies of the Hong Kong University of Science and Technology has developed an easy‐to‐apply multi‐domain VA LCD technology that can be readily implemented in LCD factories without major investment and change in current production process. [ABSTRACT FROM AUTHOR]

Chemical compatibility of water‐soluble azo‐dye photoalignment materials opens up new possibilities of thin‐film optical devices fabrication with advanced characteristics combining several polymerizable liquid crystal layers into multilayer structures of broadband quarter or half wave retarders. However when the azodye photoalignment layer is placed in‐between two layers of polymerizable liquid crystal significant increase of dye absorption is observed. Analysis of this 'Absorption Problem' concludes azodye inter‐layer field is the cause of polarization and cis‐trans equilibrium change. New water‐soluble azo‐dye photoalignment material AmA‐2522 is suggested as perspective problem solution. [ABSTRACT FROM AUTHOR]

Optically driving liquid crystal display (ODLCD) uses polarized light field to control the orientation of the liquid crystal, and the display content can be maintained without external electric field, with extremely low power consumption. However, it has a long rewriting time, which is difficult to achieve industrialization. In order to improve the rewriting performance, the influence of the rotational viscosity of the mixed system of azo-dyes (SD1, MR) and nematic liquid crystal (5CB) on the rewriting speed is investigated. The experimental results show that the electro-optical properties of SD1-5CB and MR-5CB have great changes after irradiation by polarized light, among which the SD1-5CB is the best to improve the performance. With the increase of SD1 concentration, the rotational viscosity of SD1-5CB decreases significantly due to the change of cis-trans isomerization of azo-dye, and the optimal doping concentration is 0.5 wt%. In this case, the rewriting time is shortened from 45 s to 11 s, which has the potential to broaden the application of ODLCD. [ABSTRACT FROM AUTHOR]

Herein we present the production of a two-stage wastewater treatment system for industrial azo-dye using an immobilized nitrogen-doped zinc oxide (ND-ZnO) nanoparticles and a microalgae bioreactor. The treatment system was found capable of reducing up to 95% of methylene blue wastewater in 48 h under a seminatural condition. In the first stage, the immobilized ND-ZnO chamber was found to have photocatalyzed up to 80% using natural sunlight in 4 h. In the second stage, the algae (Chlorella vulgaris) were found to be capable of repeatedly handling the semitreated wastewater and found remained active for at least 7 cycles (hydraulic retention time = 44 h, solid reaction time = 14 days). The algae not only take part in purifying the wastewater but also absorb and metabolize the toxic cleaved by-products therein. The presented system demonstrated a low-cost alternative, both in terms of production and operation, for treatment of recalcitrant azo-dye. Furthermore, unlike other pilot systems using suspended nanoparticles, expensive recovery of nanoparticles is not required and accidental discharge of nanoparticles is avoided. Toxicity assay using fish gill cell line demonstrated that the acute toxicity of the effluent was negligible. To conclude, this novel treatment system opened a new and safe way for effective yet simple treatment of azo-dye wastewater. [ABSTRACT FROM AUTHOR]

Transition and rare-earth metal oxide-supported nanomaterials have ignited an attraction in many fields such as energy, environment and etc. In this work, transition/rare-earth metal oxide-supported carbon-based nanomaterials (TRM) were prepared by hydrothermal method and it was characterized by UV-DRS, FTIR, XRD, AFM, FE-SEM, HR-TEM, and EDAX techniques. Doping levels of transition/rare-earth metal oxides on the carbon-based material impacts the photocatalytic degradation efficiency. The photocatalytic activity (PCA) of the prepared TRM was examined, and the highest degradation percentage was observed compared to other reported catalysts. TRM 2 exhibits the maximum degradation percentages of azo dye under sunlight (99.8 %) irradiation. The optimization studies were conducted, such as the effect of pH, catalyst dosage, and concentration. The optimum condition for photocatalytic degradation was pH - 6.51, TRM dosage - 10 mg, and dye concentration - 5 ppm. The kinetic studies were conducted for the various concentrations (5–20 ppm), and the rate of reaction was determined; it clearly illustrated that the reaction follows a pseudo-first-order kinetics. The enhanced PCA in the TRM 2 was due to the combination of transition/rare-earth metal oxides on the carbon-based material. This transition/rare-earth metal oxide-supported carbon-based nanomaterials (TRM) is practically helpful in degrading environmental pollutants in real-time wastewater under sunlight irradiation.

The study focused on producing and examining the properties of the 2-(((3-mercapto-5-(4-nitrophenyl)-4H-1,2,4-triazol-4-yl)imino)methyl)-4-(((4-mercaptophenyl) diazenyl)phenol) ligand (L) and its complexes with three transition metal ions, namely Ni(II), Co(II), and Cu(II). The ligand was formed through diazotization and coupling reactions between 4-aminobenzenethiol and a coupling Schiff base derived from 1,2,4-triazole. The characterization of the ligand and its metal ion complexes was carried out using analytical techniques such as FTIR, 1H- and 13C-NMR, UV-visible spectroscopy, and thermal analysis (TGA and DTG). Various physical methods were employed to synthesize and analyze the properties of the three mononuclear Co(II), Ni(II), and Cu(II) complexes with the azo-dye Schiff's base ligand. Based on the microanalysis and spectroscopic results, it was determined that the coordination between the azo Schiff base ligand and the central metal ion occurred through the NOS-donating atoms of the ligand. The analysis of the electronic spectra revealed that the synthesized Co(II) and Ni(II) complexes exhibited an octahedral geometry, while the Cu(II) complex had a distorted octahedral geometry. The implications of the finding regarding the octahedral and distorted-octahedral geometries include expanding the structural diversity in coordination chemistry, providing insights into ligand-metal interactions, and understanding the influence of geometry on properties.

In this investigation, Co–, Ni- and Cu-doped ZnO nanoparticles were prepared using precipitation methods. The characterization of the as-prepared nanomaterials was carried out using XRD, FT-IR, DRS, XPS and SEM. The XRD analysis showed that the insertion of foreign metal ions into the matrix of ZnO caused a slight shift of the positions of (100), (002) and (101) diffraction peaks of ZnO towards the lower 2θ, by comparison with pure ZnO. The DRS results showed that Co-doped ZnO nanoparticles absorb wavelengths higher than 400 nm. The estimated band gaps (eV) were 2.48, 3.17 and 3.14 for 10 %Co-ZnO, 10 %Ni-ZnO and 10 %Cu-ZnO respectively. The XPS results showed the existence of two valence states for Co and Ni (Co2+/Co3+ and Ni2+/Ni3+) while Cu exists in the form of Cu2+. The photocatalytic efficiency was evaluated under UV and visible irradiations in aqueous solution using methyl orange (MO) as an organic pollutant probe molecule. The results showed that, under visible light, the MO degradation increased significantly by doping ZnO (10 %Co-ZnO: 33.2 %; 10 %Ni-ZnO: 19.8 % and 10 %Cu-ZnO: 52.5 %) by comparison with undoped ZnO (9.3 %). The important increase in photocatalytic activity observed for the doped ZnO by comparison with pure ZnO, particularly for 10 %Cu-ZnO, has been linked to a synergistic effect of both the band gap narrowing and the increase in the lifetime of photogenerated charge carriers.

The present study investigated the degradation of an aqueous Allura Red AC (AR–AC) solution by activating hydrogen peroxide with bicarbonate using cobalt ion (Co2+) as the catalyst. Four independent variables (H2O2, NaHCO3, Co2+, and dye concentrations) were analyzed in the composite central design (CCD). AR–AC degradation was optimized using the response surface methodology (RSM). Under optimal degradation conditions (41.86 mg/L AR–AC, 5.58 mM H2O2, 2.00 mM NaHCO3, and 9.00 µM Co2+), decolorization > 99.86%, mineralization (CO2 to conversion) of 12.99%, and total nitrogen removal of 51.97% were achieved. The predicted values for the three response variables were consistent with the experimental values, with determination coefficients (R2) greater than 0.9053. Because cobalt ions (Co2+) are a source of water pollution, after oxidation, these were adsorbed on sodium bentonite (Na–Bent), obtaining a final concentration of <0.01 mg/L. Bicarbonate-activated hydrogen peroxide is a potential technology for dye wastewater treatment that operates at an alkaline pH and at ambient temperature. [ABSTRACT FROM AUTHOR]

In recent years, artificial additives, especially synthetic food colorants, were found to demonstrate wider properties compared to their natural equivalents; however, their health impact is still not totally mapped. Our study aimed to determine the long-term (30 and 90 days) exposure effect of one of the commonly used artificial food colorants, tartrazine, on NMRI mice. The applied dose of tartrazine referred to the human equivalent dose for acceptable daily intake (ADI). Further, we evaluated its impact on the transcription of a range of epigenetic effectors, members of the DNA methyltransferase (DNMT) as well as histone deacetylase (HDAC) families. Following the exposure, organ biopsies were collected from the lungs, kidneys, liver, and spleen, and the gene expression levels were determined by real-time quantitative reverse transcription PCR (RT-qPCR). Our results demonstrated significant upregulation of genes in the tested organs in various patterns followed by the intake of tartrazine on ADI. Since DNMT and HDAC genes are involved in different steps of carcinogenesis, have roles in the development of neurological disorders and the effect of dose of everyday exposure is rarely studied, further investigation is warranted to study these possible associations. [ABSTRACT FROM AUTHOR]

The textile industry is expanding globally and is considered the backbone of the world's largest source of foreign exchange. The development of the textile industry has caused environmental contamination due to its dye waste, which is complex and very difficult to resolve with chemical and physical treatments. Azo dye is one of the most widely used dyes in textile and other industries. It is one of the significantly toxic dyes, and when released in water bodies, it causes a serious threat to the environment. A bacterial strain having the potential to degrade a variety of azo dyes such as Congo red (CR), methylene blue (MB), Alizarin Red S (AR), and Remazol Brilliant Blue R (RBBR) was isolated from soil samples in the wood weathering area and further identified and characterized. Ligninolytic microorganisms produce laccase enzymes, lignin peroxidase, manganese peroxidase, and other enzymes that can decolorize dye waste from the textile industry. The research phase was qualitative and quantitative tests of ligninolytic bacteria in the decolorization process using several selected synthetic dyes, antagonism tests, and identification of potential bacteria based on 16S rDNA gene sequences. The L11 isolate showed high performance on CR dye of 82.79%, L1 isolate on dye AR of 40.51%, L7 isolate on dye MB of 38.69%, and L8 isolate on RBBR dye of 30.34%. The L11 isolate with the highest potency was identified as Bacillus paramycoides K7.2 with a similarity of 99.71%. After 7 days of incubation, the quantitative test findings are the same as the qualitative test results, with isolate L11 having the largest clear zone on CR, AR, and RBBR dyes. [ABSTRACT FROM AUTHOR]

In today's industries, a diversity of processes give rise to increasing numbers of non-biodegradable compounds that need to be degraded totally or transformed to other less toxic and/or more biodegradable compounds, before their discharge into the environment. One such compound chosen for this study is Orange II, a representative azo-dye that is widely used and easy to monitor in its degradation. The photo-Fenton process was used under heterogeneous and homogeneous conditions to study several different variables. At the end of this research, a comparative study was carried out between the two types of catalysis. It was observed that better results in primary degradation and mineralization were provided by homogeneous catalysis. The photo-Fenton process takes place effectively under heterogeneous and homogeneous catalysis conditions. The process is much faster under homogeneous conditions than under heterogeneous conditions (99.9 and 24% after 90 min, respectively, especially when only 2 ppm of iron in solution is required). Mineralization was observed through total organic carbon, through the variable C/Co as a function of time during photo-Fenton and Orange II degradation, and the data obtained for the final oxidation capacity are in agreement with the experimental percentages of mineralization. A linear fit was observed using the Chan–Chu kinetic model for heterogeneous and homogeneous catalysis. For heterogeneous catalysis, 56% mineralization was reached whereas the model predicts 63%. Regarding homogeneous catalysis, according to the model, 100% mineralization is reached because (1/σ) takes a value greater than 1 since the model calculates it on infinite time. [ABSTRACT FROM AUTHOR]

Pollution caused by the release of toxic heavy metals into the environment by industrial and farming processes has been regarded as a major problem worldwide. This has attracted a great deal of attention into restoration and remediation. Mercury is classified as a toxic heavy metal which has posed significant challenges to public and environmental health. To date, conventional methods for mercury detection rely on expensive, destructive, complex, and highly specialized methods. Evidently, there is a need to develop systems capable of easily identifying and quantifying mercury within the environment. In this way, organic-based colorimetric chemosensors are gaining increasing popularity due to their high sensitivity, selectivity, cost-effectiveness, ease of design, naked-eye, and on-site detection ability. The formation of coumarin-azo derivative AD1 was carried out by a conventional diazotization reaction with coumarin-amine 1c and N,N-dimethylaniline. Sensor AD1 displayed remarkable visual colour change upon mercury addition with appreciable selectivity and sensitivity. The detection limit was calculated as 0.24 µM. Additionally, the reversible nature of AD1 allowed for the construction of an IMPLICATION type logic gate and Molecular Keypad Lock. Chemosensor AD1 displayed further sensing applications in real-world water samples and towards on-site assay methods. Herein, we describe a coumarin-derived chemosensor bearing an azo (N = N) functionality for the colorimetric and quantitative determination of Hg2+ in organic and aqueous media. [ABSTRACT FROM AUTHOR]

The present study investigated the degradation of an aqueous Allura Red AC (AR–AC) solution by activating hydrogen peroxide with bicarbonate using cobalt ion (Co2+) as the catalyst. Four independent variables (H2O2, NaHCO3, Co2+, and dye concentrations) were analyzed in the composite central design (CCD). AR–AC degradation was optimized using the response surface methodology (RSM). Under optimal degradation conditions (41.86 mg/L AR–AC, 5.58 mM H2O2, 2.00 mM NaHCO3, and 9.00 µM Co2+), decolorization > 99.86%, mineralization (CO2 to conversion) of 12.99%, and total nitrogen removal of 51.97% were achieved. The predicted values for the three response variables were consistent with the experimental values, with determination coefficients (R2) greater than 0.9053. Because cobalt ions (Co2+) are a source of water pollution, after oxidation, these were adsorbed on sodium bentonite (Na–Bent), obtaining a final concentration of

In today’s industries, a diversity of processes give rise to increasing numbers of non-biodegradable compounds that need to be degraded totally or transformed to other less toxic and/or more biodegradable compounds, before their discharge into the environment. One such compound chosen for this study is Orange II, a representative azo-dye that is widely used and easy to monitor in its degradation. The photo-Fenton process was used under heterogeneous and homogeneous conditions to study several different variables. At the end of this research, a comparative study was carried out between the two types of catalysis. It was observed that better results in primary degradation and mineralization were provided by homogeneous catalysis. The photo-Fenton process takes place effectively under heterogeneous and homogeneous catalysis conditions. The process is much faster under homogeneous conditions than under heterogeneous conditions (99.9 and 24% after 90 min, respectively, especially when only 2 ppm of iron in solution is required). Mineralization was observed through total organic carbon, through the variable C/Co as a function of time during photo-Fenton and Orange II degradation, and the data obtained for the final oxidation capacity are in agreement with the experimental percentages of mineralization. A linear fit was observed using the Chan–Chu kinetic model for heterogeneous and homogeneous catalysis. For heterogeneous catalysis, 56% mineralization was reached whereas the model predicts 63%. Regarding homogeneous catalysis, according to the model, 100% mineralization is reached because (1/σ) takes a value greater than 1 since the model calculates it on infinite time.

New composite photocatalysts have been obtained by chemical bath deposition of CdS on top of either nanostructured crystalline ZrO2 or TiO2 films previously deposited on conductive glass FTO. Their morphological, photoelectrochemical and photochemical properties have been investigated and compared. Time resolved spectroscopic, techniques show that in FTO/TiO2/CdS films the radiative recombination of charges, separated by visible illumination of CdS, is faster than in FTO/ZrO2/CdS, evidencing that carrier dynamics in the two systems is different. Photoelectrochemical investigation evidence a suppression of electron collection in ZrO2/CdS network, whereas electron injection from CdS to TiO2 is very efficient since trap states of TiO2 act as a reservoir for long lived electrons storage. This ability of FTO/TiO2/CdS films is used in the reductive cleavage of N=N bonds of some azo-dyes by visible light irradiation, with formation and accumulation of reduced aminic intermediates, identified by ESI-MS analysis. Needed protons are provided by sodium formate, a good hole scavenger that leaves no residue upon oxidation. FTO/TiO2/CdS has an approximately 100 meV driving force larger than FTO/ZrO2/CdS under illumination for azo-dye reduction and it is always about 10% more active than the seconds. The films showed very high stability and recyclability, ease of handling and recovering. [ABSTRACT FROM AUTHOR]

Combination of several films from polymerizable liquid crystal (PLC) into single device system with complex properties faces a fabrication issue due to chemical compatibility and mutual alignment effect of the neighbouring layers. Eco-friendly green technology of high anchoring azo-dye photoalignment layer coating from water solvent provides efficient solution to hinder interlayer interaction of bottom PLC layer avoiding its chemical damage and providing unique photoalignment pattern for top PLC retarder. The advanced possibilities of green technology of photoalignment layers coated from H2O solution are demonstrated through fabrication of achromatic quarter-wave retarder system comprising formation of polimerizable liquid crystal layers on top of one another with arbitrary azimuthal photoalignment direction. The merge of photoaligned PLC retarders into single multi-layer anisotropic structure opens new approach to fabrication of thin-film phase devices with complex optical properties. [ABSTRACT FROM AUTHOR]

In this work, the static and dynamic fluorescence analyses of direct yellow 27 [C25H20Na2O9S3] had been carried out through fluorescence spectroscopic techniques in various polar protic and polar aprotic solvents at room temperature. The prominent emission peak of the molecule observed at 355.84 nm in water, and the Stokes shift of the order of 68.84 nm (Δν = 6741 cm−1) came out. We found the recorded emission peak to be slightly redshifted with increase in polarity of the solvents. The excited-state lifetime measurement of the molecule in different solvents studied and determined that mono-azo direct yellow 27 possessed a lifetime of 12.18 ns in DMSO and 6.8 ns in the water at a concentration of 100 µM. The fluorescence quantum yield (Φf) calculated as 0.41 in water and the impact of different solvents on its value also analyzed. [ABSTRACT FROM AUTHOR]

In the field of the microbial ecology of biofilms and activated sludges, it is widely accepted that the microstructure of the communities depends on the environmental factors. Nevertheless, due to their complexity, the exact mechanisms are still unknown. In this study, we applied a stepwise increase of an azo-dye concentration as a selective factor for adaptation towards biodegradation. The degrading biofilm was developed in a lab-scale sand biofilter. It functioned in a semi-continuous regime for 623 h. The concentration of the azo-dye amaranth was increased from 10 to 55 mg L−1. The effectiveness was 90% and the rate of amaranth elimination was 1.136 mg h−1. The fluorescence in-situ hybridisation (FISH) revealed zones with high activity of Pseudomonas sp. Also increasing importance of the unculturable Pseudomonas sp. and the relationships in the biofilm were found. At the final stage of the experiment, a decrease of the azoreductase activity and an increase of the catechol-1,2-dioxygenase activity were established in the depth of the biofilter. The obtained results were linked with different Pseudomonas microstructures (shown by FISH). The obtained data showed that the changes in the biofilm structure occurred accordingly to the biodegradation of the toxic compound and it included the development of cooperative microbial relationships in the key genus Pseudomonas.

Flat nonprofiled surface of photoalignment AtA‐2 azo‐dye layer possesses simultaneously low molecular orientation anisotropy and strong azimuthal anchoring energy. We explain how flat surface of alignment layer orients nematic liquid crystal and show the existence of the new photoalignment mechanism based on photo‐induced hole dipole moments in the azo‐dye layer. The dependence of anchoring energy coefficient on the square of dipole moments of the alignment layer and the liquid crystal layer is formulated, grounding the idea of chemical modification of AtA‐2 azo‐dye with molecular dipole moment ~16D to obtain novel high anchoring photoalignment material. The new AtA‐0042 azo‐dye with molecular dipole moment ~27.5D is synthesized and experimentally verified. Strong azimuthal anchoring energy over >1.4 × 10−4 J/m2 is obtained for AtA‐0042 photoalignment material layer with ~40 mJ/cm2 exposure dose. [ABSTRACT FROM AUTHOR]

We deposited homogeneous, thin, yellow-colored films of chitosan (Chi)-N,N-dimethyl-4-(2-pyridylazo)aniline (PADA) dye from an acid Chi–PADA solution by spin-coating on glass substrates. We characterized Chi, PADA, and Chi–PADA films by ATR–FTIR spectroscopy, which revealed a slight shift of 3170 and 3268 cm−1 bands, indicating H-bonding between the chitosan hydroxyl (OH) group and the amine (N) of the PADA pyridine ring. Based on these analyses, it was possible to determine the efficiency of the hydrogen bonds to form a Surface Relief Grating (SRG) on azo-polymer thin film. Moreover, we performed UV–VIS spectroscopy analysis of this film, which showed a broad band extending from 400 to 700 nm, with the maximum occurring at 428 nm. Therefore, we selected, within the absorption band, the 532 nm green laser wavelength to irradiate the azo-polymer films at room temperature. For the first time, natural polymer derivative and dye sample Chi–PADA thin films showed unique photoresponsive behavior under irradiation with two interfering laser beams. This permitted us to generate surface inscription patterning known as an SRG, which we confirmed by atomic force microscopy (AFM) and for which we determined a grating depth up to 50 nm. The present study opens the new possibility of using natural polymer-dye thin films.

In the field of the microbial ecology of biofilms and activated sludges, it is widely accepted that the microstructure of the communities depends on the environmental factors. Nevertheless, due to their complexity, the exact mechanisms are still unknown. In this study, we applied a stepwise increase of an azo-dye concentration as a selective factor for adaptation towards biodegradation. The degrading biofilm was developed in a lab-scale sand biofilter. It functioned in a semi-continuous regime for 623 h. The concentration of the azo-dye amaranth was increased from 10 to 55 mg L−1. The effectiveness was 90% and the rate of amaranth elimination was 1.136 mg h−1. The fluorescence in-situ hybridisation (FISH) revealed zones with high activity of Pseudomonas sp. Also increasing importance of the unculturable Pseudomonas sp. and the relationships in the biofilm were found. At the final stage of the experiment, a decrease of the azoreductase activity and an increase of the catechol-1,2-dioxygenase activity were established in the depth of the biofilter. The obtained results were linked with different Pseudomonas microstructures (shown by FISH). The obtained data showed that the changes in the biofilm structure occurred accordingly to the biodegradation of the toxic compound and it included the development of cooperative microbial relationships in the key genus Pseudomonas. [ABSTRACT FROM AUTHOR]

Removal of textile azo-dyes from industrial wastewater is a concerning problem in the modern societies. Adsorption of organic dyes is an alternative for removing these pollutants, but efficient and low-cost adsorbents are required. In this work, a natural (crude) bentonite was used as adsorbent to remove a model cationic (basic) textile dye (basic red 46). Some parameters such as initial dye concentration, time, pH, and temperature were studied in semi-batch experiments to obtain the best conditions for adsorption of basic red 46 (BR-46) with minimal quantity of adsorbent (10 mg in 100 mL of solution). An experimental adsorption capacity (qm) of 594 mg g−1 was determined directly from the adsorption curve for 60 mg L−1, pH=7 and 25 °C. The thermodynamic parameters ΔG°, ΔH° and ΔS° were also estimated. Several adsorption isotherms (Langmuir, Freundlich, and Temkin) and kinetic models (pseudo-first order, pseudo-second order, and intra-particle diffusion) were applied to the experimental data; thus, the best settings were obtained by Langmuir isotherm and pseudo-second order kinetic model. The comparison of results obtained for this natural bentonite with respect to some materials published in the literature reveals the excellent performance of this material for adsorption of BR-46, allowing a fast and higher removal (94% ± 4, at 10 min), under mild conditions (neutral pH, 25 °C and atmospheric pressure). [ABSTRACT FROM AUTHOR]

Graphene zirconium oxide nanocomposite (Gr@ZrO2‐NC) has been functionalized with cetyltrimethylammonium bromide (CTAB or CT) or butanediyl‐1,4, bis (N, N‐hexadecyl ammonium) dibromide (cationic gemini surfactant (CGS)). Structural, morphological, optical and thermal properties of synthesized adsorbents (Gr@ZrO2‐NC, CT‐Gr@ZrO2‐NC and CGS‐Gr@ZrO2‐NC) are investigated using XRD, FTIR, electron microscopy and TGA. CGS‐Gr@ZrO2‐NC showed faster removal efficacy (90 % within the first 25 min) for anionic azo dyes (methyl orange, MO and Congo red, CR) compared to other adsorbents. This effect may be due to the creation of stronger hydrophobic region at the surface of adsorbent with CGS. Effects of concentration, contact time and pH were also seen. The adsorption efficacy remained better even in the simultaneous presence of MO and CR. Adsorption data with time showed that the pseudo‐second‐order kinetic model has been obeyed. Adsorbents were regenerated successfully with ethylene glycol (∼83 %). [ABSTRACT FROM AUTHOR]

The treatment by Advanced Oxidation Processes (AOPs) of wastewater polluted with dyes is of particular interest in the field of environmental engineering, especially for the removal azo-dyes, representing over 50% of the global annual production of dyes. Unfortunately, most azo-dyes are non-biodegradable and can be toxic to aquatic organisms. This is the first data article that applies the methodology of response surface for the optimization of decolorization of an azo-compound using cobalt in a homogeneous medium as the catalyst of a bicarbonate activated hydrogen peroxide (BAP) system which, in turn, is an emerging technology for wastewater treatment. The Response Surface Methodology (RSM) based on a Central Composite Design (CCD) was used to evaluate and optimize the influence of three experimental variables (stoichiometric dosage of H2O2, molar ratio H2O2/NaHCO3 and cobalt concentration) on the decolorization of Ponceau 4R. Reactions were performed at 25 °C, pH 8.3 with a reaction time of 2 h. Analysis of variance (ANOVA) showed values of R2 and adjusted-R2 of 0.9815 and 0.9648, and experimental data were fit to a second-order regression model. The optimal conditions to achieve a maximum decolorization (96.31%) of a Ponceau 4R aqueous solution of 20 mg/l were: 4.73 times stoichiometric dosage of H2O2, molar ratio H2O2/NaHCO3 of 1.70 and cobalt concentration of 11.16 µM. Under the optimal reaction conditions, the influence of temperature (20, 25, 30 and 35 °C) on decolorization was evaluated and data were adjusted to second order kinetics. To verify the efficiency of the BAP system on the decolorization of Ponceau 4R, under the optimal conditions of reaction, UV–Vis spectra, at different reaction times, were measured. Additionally, blank experiments in order to evaluate the effect of individual factors in the Ponceau 4R decolorization, using BAP system, were carried out. Data showed that the Co(II)-NaHCO3-H2O2 system is a suitable technology for the decolorization of azo-dyes aqueous solutions.

Waste water from the textile industry is one of the major sources of contamination causing serious health problems. In textile waste water, dyes are the main pollutant. In this research work textile waste water was treated with various organic acid-activated clays to remove the dyes. Pink Azo dye was selected as a component to remove from waste water. Adsorbent selected was bentonite clay and was activated by acids such as phosphoric, acetic, oxalic, and citric acids. Adsorbent characteristics have been analyzed through infrared spectroscopy (FTIR) and Scanning Electron Microscope (SEM) while the removal of dye at various temperatures has been analyzed through Ultraviolet (UV) analysis. It was observed that the bentonite clay-treated with phosphoric acid had relatively maximum capacity to remove the dye while the clay treated with oxalic acid got minimum capacity to remove the dye from same waste water.

The optical sensing and redox properties of 1, 5-diphenylcarbazone (dpc) towards some divalent metal ions (Co(II), Zn(II), and Pb(II)) were investigated by absorption spectroscopy, cyclic and square wave voltammetries, and the results supported by density functional calculations (DFT). Experimental absorption spectra of dpc is characterized by the H O M O → L U M O intra-molecular inter-ring π to π* charge transfer transition in addition the lower energy π to π* and less probable n to π* transitions of the N N and C O moieties. The optical sensitivity of this system, originates from the ability of the n -electrons on the azo or C O moieties, or the acidic hydrogens of the amide and amine groups to form inter-molecular interactions with other molecules and ions. Voltammetric analyses revealed that both the azo and amidic moieties are reduced via EC mechanisms in CH 3 CN, and the molecule is not capable of stabilizing the reduced states of the divalent ions, hence, electrocatalytic hydrogen evolution in acidic media was not observed for the cobalt(II) dpc system. Image 1 • Excitation energetics of dpc is solvent and solute dependent. • The optical behaviour of dpc is dominated by inter-ring charge transfer and intra-azo n to π* transitions. • Metallo- and halo-sensing behaviour of dpc is caused by coordination to the azo moiety. • Keto-enol tautomerization favours the keto form. • The redox behaviour of dpc is sensitive to the presence of metal ions. [ABSTRACT FROM AUTHOR]

In this investigation, Co–, Ni- and Cu-doped ZnO nanoparticles were prepared using precipitation methods. The characterization of the as-prepared nanomaterials was carried out using XRD, FT-IR, DRS, XPS and SEM. The XRD analysis showed that the insertion of foreign metal ions into the matrix of ZnO caused a slight shift of the positions of (1 0 0), (0 0 2) and (1 0 1) diffraction peaks of ZnO towards the lower 2θ, by comparison with pure ZnO. The DRS results showed that Co-doped ZnO nanoparticles absorb wavelengths higher than 400 nm. The estimated band gaps (eV) were 2.48, 3.17 and 3.14 for 10 %Co-ZnO, 10 %Ni-ZnO and 10 %Cu-ZnO respectively. The XPS results showed the existence of two valence states for Co and Ni (Co2+/Co3+ and Ni2+/Ni3+) while Cu exists in the form of Cu2+. The photocatalytic efficiency was evaluated under UV and visible irradiations in aqueous solution using methyl orange (MO) as an organic pollutant probe molecule. The results showed that, under visible light, the MO degradation increased significantly by doping ZnO (10 %Co-ZnO: 33.2 %; 10 %Ni-ZnO: 19.8 % and 10 %Cu-ZnO: 52.5 %) by comparison with undoped ZnO (9.3 %). The important increase in photocatalytic activity observed for the doped ZnO by comparison with pure ZnO, particularly for 10 %Cu-ZnO, has been linked to a synergistic effect of both the band gap narrowing and the increase in the lifetime of photogenerated charge carriers. [ABSTRACT FROM AUTHOR]

• The synthesised Schiff base derived ENB and its metal complexes. • The designed sensor act as efficient-bio-active, selective, stable and linearity. • The MWCNT-[Co(ENB) 2 ]/GCE responses well in the detection of ciplactin. • Synthesised compounds screened for cytotoxicity A549 and antioxidant activities. • Molecular docking exhibits the active site and E-score of synthesized compounds. A Schiff base derivative, 4-{[(E)-{2‑hydroxy-3-[(Z)-1,3-thiazol-2-yldiazeneyl]napthalen-1-yl}methylidene]amino}benzoic acid (ENB) and some of its transition metal complexes were synthesised. The structure of the ENB and its complexes were characterised by NMR, FT-IR, mass spectra, TGA, UV–visible, PXRD and ESR techniques. Physico-chemical data suggest an octahedral geometry nature. Molecular docking for all the synthesised compounds has been performed to predict the binding affinity. The [Ni(ENB) 2 ] exhibited excellent binding score of -284.32 kcal/mol In vitro cytotoxicity activities on lungs cell line A459 exhibited significant IC 50 values and the results indicated that [Co(ENB) 2 ] is a stronger antioxidant agent. Electrochemical detection of bioactive drug ciplactin using a modified electrode, MWCNT-[Co(ENB) 2 ]/GCE showed an excellent sensing ability with a long linear range 10-90 µmol/L, sensitivity 0.4765 µAµM−1cm−2 and its LOD is 3.333 µmol/L in PBS pH 7. Further, the modified electrodehas more stability and less leaching property in the detection system. [Display omitted] [ABSTRACT FROM AUTHOR]

Catalytic degradation of textile dyes in diluted aqueous solutions with minimal consumption of energy is a great challenge for wastewater treatment and environmental protection. Efficient heterogeneous catalysts are needed to completely oxidize azo-dyes under soft conditions. In this work, catalysts of Cu–Co oxide (1:2 molar ratio) supported on halloysite (Ha) nanotubes (CuCo(5%)/Ha and CuCo(10%)/Ha) were synthesized and used in the catalytic wet peroxide oxidation of reactive yellow 145 (RY-145) and basic red 46 (BR-46). The catalysts were characterized by chemical analysis, X-ray diffraction, Raman spectroscopy, N2 adsorption isotherms, scanning electron microscopy and transmission electron microscopy. The results showed that the synthesized catalysts possess nanotubular structure with good mesoporosity, and the spinel structure CuCo2 O4 was identified as the active phase deposited on Ha. The catalysts degraded these azo-dyes in diluted solutions (22 mg l−1 of RY-145 and 35 mg l−1 of BR-46) under mild reaction conditions (25°C , atmospheric pressure, pH 4 and minimum amounts of both catalyst and H2 O2) . Significant levels of dye conversion (93.1 ± 2.2 % for RY-145 and 54.4 ± 2.0 % for BR-46) were achieved in a relatively short time. In addition, significant values of total organic carbon removal (59.5 ± 1.8 % for RY-145 and 33.9 ± 1.4 % for BR-46) were obtained, indicating the total oxidation of a significant fraction of these dyes to CO2 and H2O . [ABSTRACT FROM AUTHOR]

• Sorption of anthraquinone-dye AB-127 and azo-dye AY-17 onto FA was compared. • Two steps isotherm curves were observed for both dyes in single and binary systems. • The isotherm curves of L AB-127 were L-shaped but they were S-shaped for AY-17. • Concentration and temperature reversely affected on sorption of AB-127 and AY-17. • Both dyes could be efficiently removed by the FA from single and binary solutions. Sorptive removal of an anthraquinone-dye (Acid Blue 127, AB-127) and an azo-dye (Acid Yellow 17, AY-17) from single and binary solutions using fly ash (FA) was compared. The diffuse reflectance infrared Fourier-transform spectra and scanning electron microscopy images were used for analyses of the bare and dye-loaded sorbents. Kinetic results well fit to the McKay equation. Typical two-step isotherms were observed both in single and binary component systems. Solution activity was used instead of concentration in the construction of isotherm plots and various isotherm models were modified for the calculation of two-step isotherm curves. The Liu isotherm shows the best fit to the experimental data of both L-shaped curves of AB-127 and S-shaped curves of AY-17. The Liu sorption capacities of the FA for AB-127 increased from 7.70 × 10−5 to 3.78 × 10-4 mol/g with the increasing temperature from 25 to 60 °C whereas it decreased from 2.35 × 10-4 to 2.10 × 10-5 mol/g for AY-17 in the same temperature range. Binary sorption was studied at three different molar ratios of AY-17/AB-127 of 1/10, 1/1 and 5/1. The removal capacities of the FA for the dyes were as high as activated carbon and it could be evaluated as an efficient sorbent for in-situ treatments in plants. [ABSTRACT FROM AUTHOR]

This paper investigates the photoinduced change of refractive index in dye (methyl red, MR)-doped blue phase (DDBP) cells by illumination of a pump beam. Through excitation of light irradiation with proper photon energy, MR can transform from trans-state to cis-state and successively diffuse and anisotropically adsorb on the inner glass substrate of the DDBP cell along the direction perpendicular to the polarisation of the pump beam. The adsorbed MR molecules can effectively rotate the orientation of the liquid crystal (LC) molecules and thereby modulate the effective refractive index of the DDBP cell. The SEM images of the adsorbed regions of the illuminated DDBP samples were also taken for discussing the relation between the pump intensity and the photoinduced birefringence. [ABSTRACT FROM AUTHOR]

Abstract Removal of azo dye from wastewater with biological method is a complicated process, including decolorization and mineralization. However, there is little understanding of the functional microbial community involved in the whole dye degradation process. In this study, a simplified model using anaerobic3-oxic2-sedimentaion reactor was proposed. Acid Orange and Methyl Orange were treated as model azo dyes. In each compartment, the degradation intermediates of azo dyes were identified with UV–Vis, FTIR, HPLC-MS and GC-MS, and the corresponding microorganisms were determined with 16S rDNA high throughput Miseq sequencing. Decolorization happened in anaerobic compartments, while mineralization of the resulted aromatic amines mainly occurred under aerobic circumstance. LEfSe analysis demonstrated that the microbial community compositions were significantly influenced by the chemical structures of substrates. With t -value biplot, the relationship between azo dye degradation and microbial community structure was proposed statistically. It was found that the functional microbial communities varied with the change of azo dye degradation intermediates. Besides, cleavage of benzene ring also happened under anaerobic circumstance. This may be due to the genera of Parabacteroides and Bacteroides , which exhibited significantly positive relationships with 1,4-Benzenediol. With the new model, the performances and structures of functional microbial communities for N N- reduction and aromatic amines mineralization were characterized and the reaction mechanism was explored. Graphical abstract Image 1 Highlights • 100% of decolorization rate were obtained in anaerobic compartments. • 100% of aromatic amines were removed under aerobic situation. • Multiple linear regression combined with t -value biplot was proposed. • Degradation intermediates significantly influenced microbial community composition. • Functional microbial community structures were statistically characterized. [ABSTRACT FROM AUTHOR]

In this research, the amine functionalized magnetic silica‐based nanocomposite as a solid‐phase extraction adsorbent coupled with high‐performance liquid chromatography was applied for the preconcentration and determination of Sudan dyes in environmental waters and a food sample. The synthesized core‐shell Fe3O4@silica nanoparticles were functionalized with amino groups and characterized by scanning electron microscopy, energy‐dispersive X‐ray spectroscopy and Fourier transform infrared spectroscopy techniques. The experimental parameters optimized and under the best conditions, the sorbent was successfully used to extract the target analytes. The result showed that a good linearity with a r‐value of greater 0.990, and the limits of detection were from 0.082 to 0.12 µg L−1. The relative recoveries obtained by analysing the spiked water samples were in the range of 90–102% and the relative standard deviations were between 0.590 and 7.94%. [ABSTRACT FROM AUTHOR]

A Metal-Organic Framework (MOF), iron-benzenetricarboxylate (Fe(BTC)), has been studied for the adsorptive removal of azo-dye Orange II from aqueous solutions, where the effect of various parameters was tested and isotherm and kinetic models were suggested. The adsorption capacities of Fe(BTC) were much higher than those of an activated carbon. The experimental data can be best described by the Langmuir isotherm model (R2 > 0.997) and revealed the ability of Fe(BTC) to adsorb 435 mg of Orange II per gram of adsorbent at the optimal conditions. The kinetics of Orange II adsorption followed a pseudo-second-order kinetic model, indicating the coexistence of physisorption and chemisorption, with intra-particle diffusion being the rate controlling step. The thermodynamic study revealed that the adsorption of Orange II was feasible, spontaneous and exothermic process (−25.53 kJ·mol−1). The high recovery of the dye showed that Fe(BTC) can be employed as an effective and reusable adsorbent for the removal of Orange II from aqueous solutions and showed the economic interest of this adsorbent material for environmental purposes.

A simplified model employing anaerobic 3 -oxic 2 -sedimentaion reactor and multiple linear regression was proposed in this study. Four typical azo dyes were treated as model contaminants. Decolorization firstly happened by the cleavage of N N double bond, aromatic amines were yielded. Afterwards, deamination and desulphurization occurred, phenol and naphthol were formed. Then dearomatization reactions were detected by introducing the atoms of O 2 into the aromatic nucleus. At last complete mineralization happened, yielding CO 2 and H 2 O. Two types of functional microbial communities for N N double bond cleavage and aromatic rings broken were statistically identified with multiple linear regression and the results were presented in t-value biplots. The genera of Enterococcus , Acidaminococcus , Bacteroides , Megasphaera and Klebsiella played significantly important roles in cleavage of N N , while Pseudomonas , Anaerovorax and Longilinea demonstrated significantly positive relationship with breaking the aromatic rings. We must point out that species in the genera of Anaerovorax and Longilinea are usually reported as strictly anaerobic bacteria, while, in our study, they were abundant in aerobic compartments and significantly positive with aromatic compounds. The findings will provide important information for operation process optimization and treatment efficiency improvement in printing and dyeing wastewater treatment plant. [ABSTRACT FROM AUTHOR]

We present results on reversible light-induced solubility of disperse red 1 (DR1) dye in a hydroxypropyl cellulose (HPC) matrix. The samples were prepared by dissolution of both DR1 and HPC in acetone and left to dry overnight in air to form not totally uniform red coatings. It is observed that both heating and illumination of the samples with visible light promote the appearance of a dark red coloration inside the heated or illuminated regions. This new phenomenon is attributed to a dissolution of dye and/or disruption of DR1 aggregates. It is confirmed by visible light and FTIR spectroscopies. UV-Vis spectra evidence disappearance of a band at 400 nm, which is attributed to DR1 aggregates, upon illumination of the samples with visible light. FTIR spectra show new bands at 1600, 1508, and 1342 cm−1 that were assigned to symmetric and asymmetric stretching modes of NO2 of the dissolved DR1. Results evidence a dye solubilization process throughout repeated trans-cis isomery induced by visible light. This process is also a new feature of the light induced molecular movements of azo-dyes and may be used in future for the photo-command of polymer properties and/or light storage. This work opens new perspectives to use natural polymers and composites in photonic applications. It also reveals the strong potential of azo-materials as light powered molecular motors. [ABSTRACT FROM AUTHOR]

A nanocomposite containing zinc oxide and zinc titanate spinel was synthesized from a mixture of layered zinc hydroxide nitrate and titanium (IV) oxysulfate (theoretical Zn 2 TiO 4 :ZnO mass ratio of 10%) by calcination at 700 °C. The resulting material was characterized by XRD, TGA-DSC, FTIR, TEM, SAED, SEM, EDS mapping and Raman spectroscopy, techniques that allowed verifying a heterogeneous material constituted of tubular Zn 2 TiO 4 and granular ZnO particles. The resulting ZnO/Zn 2 TiO 4 nanocomposite was used as a photocatalyst in the advanced oxidative process (AOP) for degradation of Reactive Black 5 dye in aqueous solution. The results indicate excellent photocatalytic performance with significant removal of the integrated spectral area, which suggests significant dye degradation after 60 min. [ABSTRACT FROM AUTHOR]

Recalcitrant dyes present in effluents constitute a major environmental concern due to their hazardous properties that may cause deleterious effects on aquatic organisms. Tartrazine is a widely-used dye, and it is known to be resistant to biological and chemical degradation processes and by its carcinogenic and mutagenic nature. This study presents the use of TiO 2 (P25) nanoparticles immobilized into a poly(vinylidenefluoride–trifluoroethylene) (P(VDF–TrFE)) membrane to assess the photocatalytic degradation of this dye in a solar photoreactor. The nanocomposite morphological properties were analyzed, confirming an interconnected porous microstructure and the homogeneous distribution of the TiO 2 nanoparticles within the membrane pores. It is shown that the nanocomposite with 8 wt% TiO 2 exhibits a remarkable sunlight photocatalytic activity over five hours, with 78% of the pollutant being degraded. It was also demonstrated that the degradation follows pseudo-first-order kinetics model at low initial tartrazine concentration. Finally, the effective reusability of the produced nanocomposite was also assessed. [ABSTRACT FROM AUTHOR]

Adsorption, a popular technique for removing azo dyes from aqueous streams, is influenced by several factors such as pH, initial dye concentration, temperature and adsorbent dosage. Any strategy that seeks to identify optimal conditions involving these factors, should take into account both kinetic and equilibrium aspects since they influence rate and extent of removal by adsorption. Hence rigorous kinetics and accurate equilibrium models are required. In this work, the experimental investigations pertaining to adsorption of acid orange 10 dye (AO10) on activated carbon were carried out using Central Composite Design (CCD) strategy. The significant factors that affected adsorption were identified to be solution temperature, solution pH, adsorbent dosage and initial solution concentration. Thermodynamic analysis showed the endothermic nature of the dye adsorption process. The kinetics of adsorption has been rigorously modeled using the Homogeneous Surface Diffusion Model (HSDM) after incorporating the non-linear Freundlich adsorption isotherm. Optimization was performed for kinetic parameters (color removal time and surface diffusion coefficient) as well as the equilibrium affected response viz. percentage removal. Finally, the optimum conditions predicted were experimentally validated. [ABSTRACT FROM AUTHOR]

This work aims to investigate possible interferences due to the presence of sodium carbonate on the photodegradation of the reactive Black 5 azoic dye, both in systems containing only titanium oxide and those containing titanium oxide and hydrogen peroxide. The role of hydrogen peroxide is explicitly treated. Sodium carbonate, in fact, is often present in the wastewater of textile industries as it is used in the fiber dyeing phases. The use of TiO2 nanoparticles is emphasized, and the possible danger is underlined. Each system was subjected to ultraviolet irradiation (UV) by varying the exposure time. After the photodegrading tests, the resulting solutions were analyzed by UV-vis spectrophotometry and High-Resolution Nuclear Magnetic Resonance to measure the residual concentrations of dye. The dye degradation curves and reaction rates for different UV exposure times were obtained and discussed as a function of the used additives. All the data are repeated three times, and they differ only by a maximum of 5%. The results indicated a reduction of about 50% of the initial concentration of Reactive Black 5 after 30 min under optimal experimental conditions. The NMR analysis indicated the formation of a series of aromatic structures that were generated by the UV-induced photochemical fragmentation of the original molecule.