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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]

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]

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]

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.

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]

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.

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]

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]

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]

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 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]

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.

Despite the multidisciplinary standard treatment of glioblastoma (GB) consisting of maximal surgical resection, followed by radiotherapy (RT) plus concomitant chemotherapy with temozolomide (TMZ), the majority of patients experience tumor progression and almost universal mortality. In recent years, efforts have been made to create new agents for GB treatment, of which azo-dyes proved to be potential candidates, showing antiproliferative effects by inducing apoptosis and by inhibiting different signaling pathways. In this study we evaluated the antiproliferative the effect of six azo-dyes and TMZ on a low passage human GB cell line using MTT assay. We found that all compounds proved antiproliferative properties on GB cells. At equimolar concentrations azo-dyes induced more cytotoxic effect than TMZ. We found that Methyl Orange required the lowest IC 50 for 3 days of treatment (26.4684 μM), whilst for 7 days of treatment, two azo dyes proved to have the highest potency: Methyl Orange IC 50 = 13.8808 μM and Sudan I IC 50 = 12.4829 μM. The highest IC 50 was determined for TMZ under both experimental situations. Conclusions: Our research represents a novelty, by offering unique valuable data regarding the azo-dye cyototoxic effects in high grade brain tumors. This study may focus the attention on azo-dye agents that may represent an insufficient exploited source of agents for cancer treatment. [ABSTRACT FROM AUTHOR]

A thermo-, pH- and cyclodextrin- (CD) responsive poly(N-isopropylacrylamide) (PNIPAM), with a N,N-dimethylaminoazobenzene end group was synthesized. Using 3-mercaptopropionic acid as a chain transfer agent, PNIPAM with a well-defined COOH end group was obtained. The acid end group was transferred to the corresponding acid chloride and then functionalized with N,N-dimethyl[4-(4’-aminophenylazo)phenyl]amine. This dye-end-group-labeled polymer showed acidochromic effects, depending on the pH and the presence of randomly methylated β-cyclodextrin (RAMEB-CD). Also higher cloud-point values for the lower critical solution temperature (LCST) in the presence of RAMEB-CD were observed. Additionally, this azo-dye-end-group-labeled polymer was complexed with hyperbranched polyglycerol (HPG) decorated with β-CD to generate hedgehog-like superstructures.

[Display omitted] • A triad consisting of two azorubine ligands and sn-tetra(sulfophenyl)porphyrin has been synthesized. • Spectral-luminescent properties of the triad and its components in aqueous media have been studied. • The triad exhibits tunable sensitivity to the medium pH and local viscosity for each specific case. A triad (Az-SnP-Az) consisting of two azorubine ligands (Az) axially bonded to the sulfo-derivative of Sn(IV)-tetraphenylporphyrin [SnP(OH) 2 ] has been synthesized. The triad structure is optimized by quantum chemical calculations and confirmed by a complex of physicochemical methods. The spectral-luminescent properties of the triad and its components in aqueous media have been studied. The sensitivity of the photophysical characteristics of the triad to the concentration-dependent viscosity of the solution has been studied on a model system (binary solvent glycerol-water). It has been established that the resulting triad has the properties of a molecular rotor and exhibits high sensitivity to local viscosity at the Az and SnP absorption maxima. The ability to tune the wavelength of the radiation, allows configuring the created "molecular rotor" to monitor the local viscosity for each specific case. [ABSTRACT FROM AUTHOR]

In the present study, sludge samples were collected from the place where effluents were released by the carpet industries in Bhadohi district. Physico-chemical analysis revealed sludge samples were dark brown in color, pH (6.91 to 9.5), ECe (5.69-11.50 dSm-1), organic C (4.40 - 12.60%), N content (3.50 -13.90%), PO4 content (7.25-13.34%) and K2O content (1.02 -3.21%). Maximum population of bacterial (cfu≈106/g) isolates in sludge samples were found on NA media followed by Kings’ B and NMS. Out of 86 bacterial isolates, 39, 28 and 19 isolates were isolated on NA, Kings’ B and NMS agar media respectively. Sixteen bacterial isolates decolorized the test dyes in respective media plates, 10 decolorized congo red (CR) and 6 decolorized trypan blue (TB) up to higher concentration (25 to 150 ppm) of dyes in agar plate. Pseudomonas sp., Bacillus sp. and Azatobacter sp. and their consortium showed significant decororization of both the dyes after 24h in Nutrient broth. Consortium of C3 (Bacillus sp. + Azatobacter sp.) decolorized 94% of 100 ppm CR and 95% of TB.

A novel iron-based metal-organic framework, possessing high surface area and good catalytic activity, was proposed as a heterogeneous Fenton catalyst for degrading high concentration methylene blue ( C MB = 500 ppm). The morphology and physicochemical properties of prepared catalysts were characterized by SEM, XRD, XPS, FT-IR, Raman spectra, etc. The obtained results showed that MOF-based catalysts MIL-100(Fe) and Fe II @MIL-100(Fe) possess high surface area of 1646 and 1228 m 2 g −1 , respectively. The MB removal though adsorption by MIL-100(Fe) and Fe II @MIL-100(Fe) is respectively 27 and 6% in 30 min, due to the electrostatic interaction between negative (or positive) adsorbent and positive pollutant. However, Fe II @MIL-100(Fe) exhibited highest Fenton catalytic ability compared to MIL-100(Fe) and Fe 2 O 3 catalysts. The catalytic activity of each active site, evaluated by the turn over frequency (TOF) value, varied in the order of Fe II @MIL-100(Fe) > MIL-100(Fe) > Fe 2 O 3 . The main role of determining the decomposition efficiency, i.e., hydroxyl radical ( OH) generation, surface redox properties and surface reaction, was greatly enhanced by the synergistic effect between Fe II and Fe III in Fe II @MIL-100(Fe). Moreover, iron-based metal-organic framework retained the catalytic performance in a wide pH range of 3–8, and had a relative low iron leaching even in acidic condition. [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. [ABSTRACT FROM AUTHOR]

TiO powders were prepared through the hydrolysis of titanium isopropoxide followed by calcination at temperatures of 200 °C to 600 °C. The obtained powders were characterized by N adsorption-desorption and X-ray powder diffraction. The results confirmed strong dependence between specific surface area of the TiO powders and both the conditions of the hydrolysis process and the calcination temperature. While calcination temperature strongly affected crystallinity of the product, no significant influence of the hydrolysis conditions on this parameter was observed. TiO powders prepared at various conditions were examined as catalysts for photodegradation of Acid Red 18 in water. Photoactivities of the prepared powders were influenced by both the amount of water used to hydrolyze the TiO precursor and the temperature of calcination process. TiO samples calcined at 500 °C appeared to be the most active and the photocatalytic activities of the prepared materials increased along with the amount of water used for the hydrolysis process. [ABSTRACT FROM AUTHOR]

[Display omitted] • γ-Al 2 O 3 nanowires were successfully synthetized and extensively characterized. • Different amounts of iron were incorporated in order to obtain photoactive catalysts. • Complete decoloration of an azo-dye was achieved after 240 min of irradiation. • Evaluation of different reaction parameters was performed. γ-Al 2 O 3 nanowires (NW) were synthetized and impregnated with different amounts of iron (2, 6 and 10 wt%). Catalysts were further characterized by powder X-ray, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption isotherms, UV–visible diffuse reflectance, temperature-programmed reduction, thermogravimetric analysis, transmission electron microscopy, X-ray photoelectron spectrometry and atomic absorption. The obtained materials were evaluated as heterogeneous photocatalysts in the degradation of azo dye methyl orange as model compound employing a 125 W high-pressure mercury lamp. After 240 min under irradiation the complete decoloration and 69% of mineralization was obtained when Fe6NW was employed. When commercial γ-Al 2 O 3 was employed as support of 6 wt%. of iron and evaluated in photodegradation the final decoloration reached up to only 46%. Reaction parameters such as iron amount, catalyst amount, pH, effect of support and reuses, were evaluated. The photocatalyst was employed for five consecutive reaction cycles with only a 10% of diminish of activity, resulting in an attractive low-cost and benefit in heterogeneous catalysis. [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. [ABSTRACT FROM AUTHOR]

The UV/Vis spectra of the m-methyl red ( m-MR) ({3-[4-(dimethyl-amino) phenylazo] benzoic acid}) were examined in aqueous solutions at various acidities. These were characterized by the overlap of the different bands of m-MR. The thermodynamic acid dissociation constant, K, of the equilibrium between m-HMR (diprotic form) and m-HMR (monoprotic form) was determined as 1.02 × 10 at 25 °C, and that for the equilibrium between m-HMR and MR (basic form), K, was determined as 4.94 × 10 at 25 °C. Based on the two observed K values, the distribution diagram of the three forms of m-MR in water was constructed. The neutral monoprotic form ( m-HMR) has a maximum fraction of 0.883 at pH = 3.14. [ABSTRACT FROM AUTHOR]

This study is first report on the synthesis of novel rhodanine based azo dyes and their fluorogenic and chromogenic sensing behaviors with metal ions (Li+, Na+, K+, Rb+, Pb2+, Ni2+, Zn2+, Cu2+) by using UV-vis and fluorescence spectroscopy techniques. The results of spectroscopic experiments for rhodanine based azo dye 1a exhibited excellent selectivity for Cu2+ over the other metal ions. Furthermore, anti-bacterial studies of rhodanine azo dyes were performed towards some selected bacteria via microbroth dilution method. Obtained results showed that rhodanine ionophore 1a showed strong antibacterial activity against S.aureus. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to realize catalytic depositions of commercial titane dioxide on classic glass plates by the PMTP method, Previed Made Titanium Powder, and to characterize these deposits by MEB and DRX. As confirmed by SEM, three successive layers of photocatalyst are obtained on the glass plates in a quite homogeneous phase as well as it is confirmed that the anatase accounts for 75% after the calcination treatment by the PMTP method. The photocatalytic reactivity is evidenced with the determination of the rate constants of degradation of the dye cibacron green RG12, used as target, on the fixed TiO2 bed (0.010 min-1) compared to the direct photolysis in homogenous aqueous phase 0.001 min-1. Optimization of the process was explored by studying the dependence of the liquid flow rate and the absorption of photon by the photocatalyst on the kinetic rate constants of the dye photodegradation. [Copyright &y& Elsevier]

Abstract: MCM-41 materials were modified with Cr, Fe, Co and Ti and characterized by ICP, XRD, N2 adsorption, UV–Vis DRS and TPR. Their photo-catalytic activity was evaluated for the degradation of Acid Orange 7 (AO7) in aqueous suspensions irradiated by artificial UV–Vis and visible light. The results showed that the Cr-modified catalysts exhibited the highest activity under visible light. The presence of Cr6+ highly dispersed on the internal surface of the MCM-41 structure would have a significant influence on the photo-activity. Thus, the lack of a notable increment in the activity when the Cr loading was duplicated is probably due to the increased presence of inactive Cr3+ species. Upon the TiO2 loading, an increase in the degradation was not observed. It is suggested that the Cr3+ species, as Cr2O3 clusters and/or α-Cr2O3 nano-particles, could avoid the desired heterojunction between Cr6+ and titania species. [Copyright &y& Elsevier]

Abstract: This study evaluated the treatability of simulated textile wastewaters in a bench-scale experimental system, comprising an anaerobic biofilter, an anoxic reactor and an aerobic membrane bioreactor. The Reactive Orange 16 (RO16) was used as model of azo dye. The proposed system was demonstrated to be effective in the treatment of the synthetic wastewater under the operating conditions applied in the study. The results demonstrate that neither the azo dye, nor the aromatic amines formed by the anaerobic azo-bond cleavage seem to significantly affect the COD and nitrogen removal under the operating conditions applied. Although aromatic amines are considered easily degradable under aerobic conditions, the results confirms that at least the sulfonated aromatic amines formed under anaerobic conditions from the RO16 are recalcitrant to biodegradation and therefore aromatic amines are still a matter of concern for the biological treatment of textile wastewater. [ABSTRACT FROM AUTHOR]

Abstract: To promote bio-based products for the industry, six bio-organic substances (cHALi) isolated from yard trimmings (green) and food (humid) urban residues aged under aerobic digestion for 0–60 days were investigated for their potential to perform as sensitizers for azo-dyes photodegradation. Ethylorange (EO) was used as probe molecule at 5mgL−1 starting concentration and irradiated in a closed Pyrex® cell with a Xenon (1500W) lamp and a cut-off filter for wavelengths below 340nm or in a cylindrical photochemical reactor equipped with a 125W medium pressure Hg lamp. The cHALi/EO ratio in the starting EO solution varied in the 0–200 (w/w) range. The % dye abatement was found a function of the irradiation time, of the type of cHALi substance and of the cHALi/EO ratio. The best results were achieved with cHALi isolated after 7 days biomass aerobic digestion. Total dye abatement was achieved within relatively short few hours. A progressive dye mineralization was observed under the same experimental conditions. On the contrary no significant degradation was evident for the cHALi substances within the same irradiation time. Several hydroxylated azo compounds were identified as likely responsible of residual color after total EO abatement. The results, coupled to the previously reported good performance of the same cHALi substances as auxiliaries for textile dyeing, augur well for the development of both efficient and environmentally friendly textile dyeing processes. [Copyright &y& Elsevier]