Oxidation Of Dye Research Articles

Preparation of Activated Carbon/N-doped Titania Composite for Synergistic Adsorption-photocatalytic Oxidation of Batik Dye

A synergetic improved composite TiO2 photocatalysts was successfully synthesized by using nitrogen (N) as a dopant and activated carbon (AC) as synergetic compound. Two different types of AC prepared from Garcinia mangostana shell and commercial AC obtained from palm shell were chosen as synergetic compound. Thus synthesized composites was further characterized by Brunauer-Emmett-Teller (BET) surface analyzer and UV-visible light spectroscope. The doping of N resulted in a better solar light utilization potential. Furthermore, synergizing with AC contributed for the improved BET surface area and pore size distribution. The synergetic adsorption-photocatalytic activity was investigated by removing a commercial batik dye namely Remazol Brilliant Blue (RBB) under direct solar irradiation. The synergetic experiments showed that commercial AC synergized with N-TiO2 resulted with a maximum removal efficiency of ∼80% in 6 h.

A novel catalyst of ceria-nanorods loaded on carbon xerogel for catalytic wet oxidation of methyl green dye

In this study, promising catalysts of ceria nanorods-supported on the porous carbon xerogels via impregnation route were prepared. Three different molar concentrations of ceria catalysts (0.15, 0.25 and 0.50 mol/L) loaded onto carbon xerogels and denoted as follows 0.15Ce/CX, 0.25Ce/CX and 0.50Ce/CX were studied in the catalytic oxidation of methyl green (MG) dye. Nanorods-like shape of the CeO2 supported on the carbon xerogel was determined using both scanning electron microscope (SEM) and transmission electron microscope (TEM). Other techniques such as FTIR, XRD and N2 adsorption–desorption were investigated. The catalytic activity of the obtained samples was examined under various variables such as ceria loading, initial concentrations of dye, H2O2 dose and temperature to optimize the operating conditions. Catalytic wet oxidation experiments revealed that 0.25Ce/CX catalyst has the highest catalytic activity toward degradation of MG dye. The presence of ceria generated a large content of reactive basic oxygen species at the surface of CX and thus enhanced the catalytic oxidation of the pristine CX support. The optimal parameters showing efficient catalytic oxidation toward MG dye found to be 0.25 mol/L cerium loading, 0.139 mol/L H2O2 and temperature of 40 °C at pH 6.0 where 100% degradation of MG dye was obtained within 30 min. The maximum removal of dye through adsorption process only was reached to 54 and 42% onto CX and 0.25Ce/CX at 120 min. Conclusively, the studied catalytic system assessed that there was a synergetic effect as a result of a combination of basic oxygen groups and redox properties of CeO2 at the surface of CX which is effective for a heterogeneous Fenton-catalysis in liquid-phase processes.

<b>Influence of pH and concentration on the decolorization and degradation of BR red azo dye by ozonization

Ozone application has been generally reported based only on the oxidation of textile dyes. In this study, a central composite design and surface response methodology were applied to optimize operational parameters pH and concentration of the dye in the decolorization process. The oxidation of Corafix BR Red Azo dye in aqueous solutions was carried out in a semi-batch bubble column reactor with ozone production at 0.702 g hour -1 . Tests were performed at pH 4, 7 e 10 and initial dye concentration of 50, 100 and 150 mg L -1 . The maximum removal efficiency was 98% for pH 10 and initial dye concentration of 50 mg L -1 with pseudo-first order constant rate (k 1 ) of 0.0595 min -1 . Statistical analysis determined the influence of pH and dye concentration in the decolorization process. The pH presented a positive effect on the decolorization while the variation in dye concentration had a negative effect on the same variable, indicating the higher the pH and the lower the initial concentration of dye, the higher the efficiency. Toxicity tests performed before and after ozonization showed acute toxicity for the test organism Daphnia similis with higher percentage of mortality after ozonization.

Fluoroalkyl phthalocyanines: Bioinspired catalytic materials

The design of self oxidation-resistant catalytic materials based on organic molecules, although advantageous due to the ability to control their structures, is limited by the presence of labile C–H bonds. This mini review summarizes recent work aimed at first-row transition metal complexes of a new class of coordinating ligands, fluoroalkyl-substituted fluorophthalocyanines, R[Formula: see text]Pcs, ligands in which all, or the majority of their C–H bonds are replaced by a combination of fluoro- and perfluoroalkyl groups yielding porphyrin-bioinspired catalyst models. In the case of homogeneous systems, cobalt(II) complexes catalyze the aerobic oxidation of thiols to disulfides, a reaction of both biological significance and industrial importance. Zinc(II) complexes photo-generate excited state singlet oxygen, [Formula: see text]O[Formula: see text], resulting in both the incorporation of O[Formula: see text] in C–H bonds or, depending on the reaction parameters, oxidation of dyes, model pollutants. Catalyst heterogenization using oxidic and other supports yields stable, active hybrid materials. Functionalized R[Formula: see text]Pcs with acidic (–COOH) or basic (–NH[Formula: see text]R[Formula: see text], [Formula: see text] 2) groups exhibit scaffolds that afford both conjugation with biological vectors for theranostic applications as well as solid-supported materials with superior stability. Electrodes modified with hybrid R[Formula: see text]Pc-containing supports have also been used in photo-oxidations, replacing enzymes and H[Formula: see text]O[Formula: see text] associated reagents with a combination of light and air. An analytical device employed for the nano-level detection of environmentally deleterious antibiotics has been constructed.

Electrochemical Decontamination Process an Effective Alternative to Treat Textile Effluents

Keeping in view the growing concern regarding aquatic pollution by effluent water from textile industries containing complex compounds, the present study was under taken with the view to study the efficiency of the removal by electrochemical oxidation. In recent year the use of electrochemistry for the investigation of environmental pollution is being thoroughly investigated. Reactive dye mainly composed of complex organic molecules are highly stable to decomposition in normal condition. Textile industry wastewater containing dyes poses a chronic and synergistic effects to environment. This study examines the electrochemical oxidation of the organic dyes. All the experiments were performed using a Filter Press Flow Cell Reactor containing Ti/Ti0.7Ru0.3O2 anode and stainless steel as cathode in which impact of the current density (5 – 20 mA cm-2), electrolytes (NaCl, Na2SO4, H2SO4), Sodium chloride concentration (0.02 – 0.10 mol L-1) were studied. The electrode used were characterized by the cyclic voltammetry experiments. The Reaction Kinetics and energy consumption parameters were studied of the electrochemical process. Results obtained in this research clearly demonstrated that the effect of the electro generated strong oxidant species active chlorine, depends on electro catalytic mechanism followed on surface of Ti/Ti0.7Ru0.3O2 resulting in the improvement of the color. Results also confirmed a high removal efficiency according to environment and electrolyte used in the process. However, there is a limit of NaCl for treating real effluents avoiding the formation of organochloride compounds; and it is a subject of critical importance, from the environmental point of view, to apply this alternative treatment. Keyword: textile effluents, contaminants, electrochemical process, Kinetics

Carbon/FexOy magnetic composites obtained from PET and red mud residues: paracetamol and dye oxidation

ABSTRACTComposite materials from PET and red mud (RM) wastes were used as catalysts for environmental application such as the wastewater treatment. The PET-RM catalysts were obtained by a mechanical mixture of the residues followed by thermal treatment under an N2 atmosphere (300°C/1 h). An additional activation of the composites with CO2 was investigated (at 800–900°C) to reduce the red mud basicity. The CO2 activation affected the composites surface area and reduced their carbon content. XRD revealed that the haematite (α-Fe2O3) and maghemite/magnetite are the main iron oxides present in the composites. Mössbauer characterization indicated the formation of reduced iron species (Fe2+), highly reactive, after the composites heat treatment. The materials were very active catalysts for methylene blue (MB) and paracetamol (PRC) removal from aqueous solution. The catalytic activity revealed to be dependent on the surface area and mainly of the presence of reduced iron species in the catalysts. The MB removal reached 97% for both PET-RM 800/2 h and PET-RM 800/5 h, after 1 h of reaction. In the case of PRC, the highest removal was also obtained for PET-RM 800/2 h and PET-RM 800/5 h, of ≈25% and 40%, respectively. The contaminants removal mechanism likely occurred through combined adsorption and Fenton-like oxidation processes.

Photocatalytic Oxidation of Azo Dyes and Oxalic Acid in Batch Reactors and CSTR: Introduction of Photon Absorption by Dyes to Kinetic Models

The possibilities of treating industrial effluents and water purification by advanced oxidation processes have been extensively studied ; photocatalysis has emerged as a feasible alternative solution. In order to apply the photocatalytic treatment on a larger scale, relevant modeling approaches are necessary. The scope of this work was to investigate the applicability of recently published kinetic models in different reactor systems (batch and CSTR) under UVA or UVC irradiation and in combination with two types of TiO2 catalyst, AEROXIDE® P25 and PC-500 for degradation of azo dyes (C.I. Reactive Violet 2, and C.I. Mordant Yellow 10), oxalic acid and their mixtures. The influences of reactor geometry and irradiation intensities on pollutant oxidation efficiency were examined. The effect of photon absorption by dyes in water matrix was thoroughly studied. Relevant kinetic models were introduced to the mass balance for particular reactor system. Resulting models were sufficient for description of pollutant degradation in batch reactors and CSTR. Experimental results showed 1.15 times higher mineralization extents achieved after 7 cycles in CSTR than in batch photoreactor of similar geometry within the equivalent time-span. The application of CSTR in-series could simplify the photocatalytic water treatment on a larger scale.

Radioresistant Cervical Cancers Are Sensitive to Inhibition of Glycolysis and Redox Metabolism.

Highly glycolytic cervical cancers largely resist treatment by cisplatin and coadministered pelvic irradiation as the present standard of care. In this study, we investigated the effects of inhibiting glycolysis and thiol redox metabolism to evaluate them as alternate treatment strategies in these cancers. In a panel of multiple cervical cancer cell lines, we evaluated sensitivity to inhibition of glycolysis (2-deoxyglucose, 2-DG) with or without simultaneous inhibition of glutathione and thioredoxin metabolism (BSO/AUR). Intracellular levels of total and oxidized glutathione, thioredoxin reductase activity, and indirect measures of intracellular reactive oxygen species were compared before and after treatment. Highly radioresistant cells were the most sensitive to 2-DG, whereas intermediate radioresistant cells were sensitive to 2-DG plus BSO/AUR. In response to 2-DG/BSO/AUR treatment, we observed increased levels of intracellular oxidized glutathione, redox-sensitive dye oxidation, and decreased glucose utilization via multiple metabolic pathways including the tricarboxylic acid cycle. 2-DG/BSO/AUR treatment delayed the growth of tumors composed of intermediate radioresistant cells and effectively radiosensitized these tumors at clinically relevant radiation doses both in vitro and in vivo Overall, our results support inhibition of glycolysis and intracellular redox metabolism as an effective alternative drug strategy for the treatment of highly glycolytic and radioresistant cervical cancers.Significance: This study suggests a simple metabolic approach to strike at an apparent Achilles' heel in highly glycolytic, radioresistant forms of cervical cancers, possibly with broader applications in cancer therapy. Cancer Res; 78(6); 1392-403. ©2018 AACR.

Enhancement of CdS nanoparticles photocatalytic activity by Pt and In2O3 doping for the degradation of malachite green dye in water

A hydrothermal method was used to prepare CdS nanoparticles, and a photoassisted deposition method was used to prepare 0.5wt% In2O3/CdS, 0.5wt% Pt/CdS and 0.5wt% Pt, In2O3/CdS nanoparticles. Different techniques, such as UV–Vis, XPS, TEM, XRD, PL and BET surface area, were used to characterize the prepared materials. The results reveal that the doping of Pt, In2O3 on the surface of CdS nanoparticles plays an important role in the control electron-hole recombination rate. The photocatalytic performance of CdS, 0.5wt% In2O3/CdS, 0.5wt% Pt/CdS, and 0.5wt% Pt, In2O3/CdS nanoparticles was studied by measuring their photocatalytic oxidation of malachite green dye under visible light. Photocatalytic parameters such as the type of doped materials, photocatalyst dosage and photocatalytic stability were also studied. The photocatalytic activity of CdS is lower than that of doped cadmium sulphide nanoparticles. This can be attributed to the fact that the addition of Pt or In2O3 or both In2O3 and Pt to CdS nanoparticles decreases the electron-hole recombination rate or alternatively due to the transfer of electrons between the doped metal and CdS nanoparticles.

Kinetic and catalytic analysis of mesoporous metal oxides on the oxidation of Rhodamine B

In this study, we demonstrate the synthesis and catalytic activity of different mesoporous transition metal oxides, silica (SiO2), copper oxide (CuO), chromium oxide (Cr2O3), iron oxide (Fe2O3) cobalt oxide (Co3O4), cerium oxide (CeO2) and nickel oxide (NiO), on the oxidation of a pollutant dye, Rhodamine B (RhB). These metal oxides were synthesized by inverse micelle formation method and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), adsorption-desorption isotherms (BET) and H2-temperature programmed reduction (TPR). UV–vis spectrophotometry was used to monitor the time-resolved absorbance of RhB at λmax = 554 nm. Mesoporous copper oxide was calcined at different final heating temperatures of 250, 350, 450 and 550 °C, and each mesoporous copper oxide catalyst showed unique physical properties and catalytic behavior. Mesoporous CuO-550 with the smallest characteristic path length δ, proved to be the catalyst of choice for the oxidation of RhB in aqueous media. We observed that the oxidation of RhB in aqueous media is dependent on the crystallite size and characteristic path length of the mesoporous metal oxide. The Langmuir-Hinshelwood model was used to fit the experimental data and to prove that the reaction occurs on the surface of the mesoporous CuO. The thermodynamic parameters, EA, ΔH#, ΔS# and ΔG# were calculated and catalyst recycling and reusability were demonstrated.

Enhanced Oxidation of Azo Dye Using Ag-SiO2 Nanoparticle and Peroxydisulfate and Kinetic Study

Present work investigates the capability of oxidative treatment process in the presence of nano silver doped on silicate particles for decolorization of a widely used azo dye, C.I. Direct Blue 129 (DB129) in water samples. Solutions with initial concentration of 20 mgL-1 of dye, within the range of generic concentration in textile wastewaters, were treated under ambient conditions of initial pH of 6.7 and temperature of 25oc. The operational parameters evaluation including dye and peroxydisulfate concentration, initial pH, nanoparticles dosage and reaction time was studied in an endeavor to reach the higher dye removal efficiency. Subsequently, a removal more than 90% of dye was attained by applying the optimal operational conditions as follow: 0.4 g of catalyst, 20 mgL-1 of dye, 5 mM of peroxydisulfate and initial pH of 6.7 in 35 min. Moreover, kinetic study for various parameters in several conditions for treatment process was investigated. Pseudo- first-order reaction rate constants were calculated for the systems. The morphology and crystal structure of Ag-SiO2 nanoparticles were characterized by means of Transmission Electron Microscope (TEM).

Protective effect of conditioner agents on hair treated with oxidative hair dye.

Hair coloring is broadly used by women and men either to change their natural hair color or to delay the onset of gray hair. Oxidative dyes may damage the hair, as chemical and physical processes are required to convert the fiber structure and, consequently, alterations in its mechanical and surface properties. The aim of this study was to evaluate the protective effect of silanetriol (and) Panthenol, PEG-12 dimethicone, and hydrolyzed silk (and) hydrolyzed milk protein (and) lactose as conditioner agents on hair treated with oxidative hair dye by protein loss, combability, and breaking strength. In this research, we analyzed the untreated hair (sample I) and the effect of oxidative hair dye emulsions, with or without conditioner agents (sample II) silanetriol (and) Panthenol (sample III), PEG-12 dimethicone (sample IV), and hydrolyzed silk (and) hydrolyzed milk protein (and) lactose (sample V) on Caucasian hair. The hair samples were submitted to protein loss quantification, breaking strength, and combing analysis. For protein loss, the results were: IIa =Va >IVb >IIIc >Id . For the breaking strength: Ie =IIe =IIIe =IVe =Ve . For the combing analysis for wet and dry hair, the results were, respectively: IIa >IIIb =IVb >Vc >Id and IIA >IIIb =Vb >IVc =Ic . Data classified by different letters presented statistically significant alterations, α=5, P≤. 05, n=15. Based on these results, the incorporation of conditioner agents into emulsion blond color decreased the damage caused by the coloring process.

Optimization of Disperse Blue 3 mineralization by UV-LED/FeTiO3 activated persulfate using response surface methodology

Abstract Response surface methodology based on Box-Behnken design (BBD) was successfully applied for the optimization of the UV-LED/FeTiO3 activated persulfate (PS) process. Disperse Blue 3 (DB3) azo dye oxidation was carried out in a quartz jacketed stirred batch reactor using 405 nm UV at 10 W/m−2 as radiation source. The effects of temperature, catalyst concentration and persulfate dose upon the total organic carbon (TOC) removal were investigated. Optimum operating conditions were found to be: ilmenite: 320 mg/L−1, PS: 1.56 g/L−1 and 67 °C. Under these conditions, 96% mineralization was achieved. Ecotoxicity of the final effluent was evaluated using Aliivibrio fischeri bacteria, finding a negligible toxicity.

Rutile TiO2 nanorods/MWCNT composites for enhanced simultaneous photocatalytic oxidation of organic dyes and reduction of metal ions

This work aims to enhance the charge separation and the photocatalytic performance of TiO2 by combining two ways of modification synthesizing TiO2 Nanorods with modified morphology and anchoring on the surface of multi-walled carbon nanotubes (MWCNT). Simple hydrothermal method is performed to synthesize pure rutile TiO2 Nanorods/MWCNT composite. The photocatalytic activity of the nanocomposite is evaluated for the degradation of the organic dye Bromophenol blue (BPB). An enhancement in the photocatalytic activity is observed using TiO2 Nanorods/MWCNT composite as compared to pure TiO2 Nanorods. A synergism between the MWCNT and the TiO2 Nanorods is expected to suppress the recombination of photogenerated electron–hole pairs and hence the photocatalytic activity. Moreover, simultaneous degradation of BPB and reduction of Ag(I) is studied using TiO2 Nanorods/MWCNT nanocomposite. Enhancement in the photocatalytic degradation of BPB is observed in the presence of Ag(I) as compared to O2 as electron acceptor due to higher TiO2 electron transfer reaction rate to the Ag(I) ion as compared to its rate to the dissolved O2. The results provide an effective method for dual benefits for the wastewater purification from organic and inorganic pollutants.

Application of a novel definitive screening design to in situ chemical oxidation of acid orange-II dye by a Co2+/PMS system

In this work, a novel definitive screening design (DSD) was initially used to investigate the in situ chemical oxidation of acid orange-II (AO II) dye using a homogeneous cobalt-catalyzed peroxymonosulfate (Co2+/PMS) system.

Novel double layer film composed of reduced graphene oxide and Rose Bengal dye: design, fabrication and evaluation as an efficient chemosensor for silver(i) detection

A novel silver-chemosensor fabricated with reduced graphene oxide and Rose Bengal (RB) based on the interaction of Ag+ and RB.

The Dependence of Oxidation Parameters and Dyes’ Molecular Structures on Microstructure of Boron-Doped Diamond in Electrochemical Oxidation Process of Dye Wastewater

In this study, the microstructure of boron-doped diamond (BDD), such as grain size, grain boundaries, surface boron concentration, film thickness, ratio of sp(3)/sp(2) was manipulated by adjusting the deposition parameters of hot filament chemical vapor deposition. Furthermore, Reactive orange 1 simulated dye wastewater was treated to discuss the degradation relationship between the microstructure of BDD electrodes and oxidation parameters. BDD electrode showed the worst electrocatalytic performance toward simulated dye wastewater, but exhibited the highest sensitivity to degradation parameters. In addition, the degradation processes of 8 kinds of synthetic dyes with different molecular structures were compared and the degradation relationship between the microstructure of BDD and the molecular structure of dyes was investigated. The degradation of refractory dyes were much more dependent on the microstructure of BDD electrodes compared to easily degradable ones, indicating that the optimization of oxidation parameters and the electrode microstructure are more effective to the degradation of refractory organic pollutants.

Amplification of surface-enhanced Raman scattering by the oxidation of capping agents on gold nanoparticles.

Surface-enhanced Raman spectroscopy is a powerful analytical method, and is especially useful for the detection of nitrogen- and sulfur-containing organic substances in trace amounts. SERS substrates with high enhancement factors can be produced via the aggregation of gold nanoparticles, leading to the formation of ‘hot spots’ – regions of highest electric field intensity and Raman scattering enhancement. Thus, the availability of gold surfaces in ‘hot spots’ for the adsorption of analyte molecules strongly influences the enhancement factor of a substrate. We studied the kinetics of oxidation of dyes with hydrogen peroxide in the presence of citrate-capped gold nanoparticles and discovered the amplification of surface-enhanced Raman scattering, probably due to the oxidation of citrate ligands and the additional adsorption of dye molecules onto vacant spots on the gold surface. Maximum amplification was observed with 3% (v/v) hydrogen peroxide in the reaction medium. Under optimized conditions, model analytes can be detected at concentrations as low as 1 × 10−9 M, which is ten times lower than the detection limit without hydrogen peroxide addition.

Titanium dioxide (TiO2)-decorated silver indium diselenide (AgInSe2): novel nano-photocatalyst for oxidative dye degradation

Novel titanium-dioxide-decorated silver indium diselenide nano-photocatalyst for enhancement in photocatalytic dye degradation efficiency of three different dyes, namely, MB, MO, and RhB.

Oxidation of azo and anthraquinonic dyes by peroxymonosulphate activated by UV light

ABSTRACTThe photochemical degradation of two azo and two anthraquinonic dyes was performed using potassium peroxymonosulphate (Oxone®) activated by UV radiation. The fast decolourization of all dyes was observed within 6 min of UV irradiation, with corresponding dye decays higher than 80%. The kinetic rate constants of the dyes' decay were determined, along with the energetic efficiency of the photochemical treatment, taking into account the influence of a few anions commonly present in real wastewaters (i.e., chloride, nitrate, carbonate/bicarbonate and phosphate ions). Chloride and carbonate/bicarbonate ions enhanced dye degradation, whereas phosphate ions exerted an inhibitory effect, and nitrates did not have a predictable influence. The dye decolourization was not associated with efficient mineralization, as suggested by the lack of a significant total organic carbon (TOC) decrease, as well as by the low concentrations of a few detected low molecular weight by-products, including nitrate ions, formaldehyde and organic acids. High molecular weight by-products were also detected by mass spectrometry analysis. The investigated process may be proposed as a convenient pre-treatment to help dye degradation in wastewater during combined treatment methods.