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Sequential anaerobic and electro-Fenton processes mediated by W and Mo oxides for degradation/mineralization of azo dye methyl orange in photo assisted microbial fuel cells
摘要： The intensification of the degradation and mineralization of the azo dye methyl orange (MO) in contaminated water with simultaneous production of renewable electrical energy was achieved in photo-assisted microbial fuel cells (MFCs) operated sequentially under anaerobic - aerobic processes, in the presence of Fe(III) and W and Mo oxides catalytic species. In this novel process, the W and Mo oxides deposited on the graphite felt cathodes accelerated electron transfer and the reductive decolorization of MO. Simultaneously, the mineralization of MO and intermediate products was intensified by the production of hydroxyl radicals (HO?) produced by (i) the photoreduction of Fe(III) to Fe(II), and by (ii) the reaction of the photochemically and electrochemically produced Fe(II) with hydrogen peroxide, which was produced in-situ during the aerobic stage. Under anaerobic conditions, the reductive decolorization of MO was driven by cathodic electrons, while the partial oxidation of the intermediates proceeded through holes oxidation, producing N,N-dimethyl-p-phenylenediamine. In contrast, under aerobic conditions superoxide radicals (O2?-) were predominant to HO?, forming 4-hydroxy-N,N-dimethylaniline. In the presence of Fe(III) and under aerobic conditions, the oxidation of the intermediate products driven by HO? superseded that of O2?-, yielding phenol and amines, via the oxidation of 4-hydroxy-N,N-dimethylaniline and N,N-dimethyl-p-phenylenediamine. These sequential anaerobic and electro-Fenton processes led to the production of benzene and significantly faster oxidation reactions, compared to either the anaerobic or the aerobic operation in the presence of Fe(III). Complete degradation and mineralization (96.8 ± 3.5%) of MO (20 mg/L) with simultaneous electricity production (0.0002 kWh/kg MO) was therefore achieved with sequential anaerobic (20 min) - aerobic (100 min) operation in the presence of Fe(III) (10 mg/L). This study demonstrates an alternative and environmentally benign approach for efficient remediation of azo dye contaminated water with simultaneous production of renewable energy.
关键词： azo dye,decolorization,photo-assisted microbial fuel cells,electro-Fenton,mineralization
更新于2025-09-23 15:23:52
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141 Induction Heating of TiO 2 Coating on SS Substrate for Photocatalysis 2016 60 3 Induction Heating Consolidation of TiO 2 Sol-Gel Coating on Stainless Steel Support for Photocatalysis Applications
摘要： A high-frequency induction heater was used to sinter titanium dioxide thin film on stainless steel plates with the aim of being used as photo-electrodes in wastewaters treatment. To validate the use of this sintering technique, the electrodes were prepared using sol-gel and dip-coating, followed by two different annealing processes for comparison: a conventional furnace and a high-frequency induction heating. To characterize the electrodes, X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical and photocatalysis tests were performed. Anatase and rutile phases were obtained for both annealing techniques. A more regular surface morphology was achieved via the induction heating (IH) treatment at 300 oC. The impedance study showed a lower resistance of IH samples, representing an improvement in the charge carrier separation and its fast transfer to the surface of the electrode. The photo-oxidation of methylene blue exhibited a higher degradation compared with the conventional furnace samples prepared in this study.
关键词： Photocatalysis,Azo dye,Coatings,Electrochemical techniques,Titanium dioxide,Induction heating sintering
更新于2025-09-23 15:23:52
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Electronic structure and UV–Vis spectra simulation of square planar Bis(1-(4-methylphenylazo)-2-naphtol)-Transition metal complexes [M(L)2]x (M?=?Ni, Pd, Pt, Cu, Ag, and x?=???1, 0, +?1): DFT and TD-DFT study
摘要： DFT/B3LYP calculations with full geometry optimizations have been carried out on 1-phenylazo-2-naphthol and their metal complexes of formula M(MePhNap)2 (M = Ni, Pd, Pt, Cu, Ag, and MePhNap = 1-(? 4-methylphenylazo)-2-naphtol) in their neutral, oxidized, and reduced forms. The predicted structures provide to the M(II) metal ions the square planar geometry and distorted azo ligand. The TD-DFT theoretical study performed on the optimized geometry allowed us to predict the UV–Vis spectra and to identify quite clearly the spectral position and the nature of the different electronic transitions according to their molecular orbital localization. Large HOMO-LUMO gaps are calculated for all optimized structures suggesting good chemical stabilities, hence, reproducing the available UV–Vis spectra and compared to that of free ligand. The electronic spectra obtained in DMSO and ethanol polar solvents predict more important red shifts than those obtained in hexane as nonpolar one.
关键词： Electronic transitions,Molecular orbital localization,Metal-ligand coordination,Azo dye
更新于2025-09-23 15:21:21
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Enhanced UV and visible light - driven Photocatalytic degradation of Tartrazine by Nickel-doped Cerium oxide Nanoparticles
摘要： Nickel-doped cerium oxide nanoparticles were synthesized via a simple aqueous coprecipitation method. The synthesized nanoparticles were thoroughly characterized by PXRD, TEM, SEM, EDX, Raman, and UV-Vis spectroscopic techniques. XRD study confirmed the doping of nickel in the cerium oxide lattice. The shift in Raman spectra revealed the formation of nanoparticles in their pure phase with fluorite structure. EDX revealed the formation of a solid solution on doping Ni- to CeO2. SEM images revealed considerable agglomeration. TEM analysis asserted the average particle size of 8-10 nm with a well-defined spherical shape. The particle size was found to be sensitive to dopant concentration, i.e., it decreased with increase in the concentration of the dopant. A comparative UV-visible spectroscopic analysis showed the remarkable red shift in the band gap of nickel-doped cerium oxide nanoparticles. Investigation of photocatalytic activity towards degradation of azo dye tartrazine showed that 3 mol% and 5 mol% Ni- CeO2 nanoparticles exhibited 53.4% and 63.7% photodegradation respectively under visible irradiation while 57.4% and 65.4% respectively under UV irradiation. The study suggests that the band gap of cerium oxide nanoparticles can be easily tuned (decreased) by doping of nickel at different concentrations. The observed improved photocatalytic activity upon Nickel doping is attributed to the narrow band gap.
关键词： azo dye,mechanism,tartrazine,photocatalysis,Nickel-doped cerium oxide nanoparticles
更新于2025-09-23 15:21:01
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Pulsed light for a cleaner dyeing industry: Azo dye degradation by an advanced oxidation process driven by pulsed light
摘要： Water pollution by wastewater containing dyes is an environmental issue that can be mitigated by the use of advanced oxidation processes (AOP). Pulsed light (PL) is an emerging food processing technology that uses eco-friendly lamps and can potentially be adapted as light source of an UV-based AOP. In the present work, a PL/H2O2 process was tested for the decolourization of two azo dyes, and a pulsed light/H2O2/ferrioxalate process was tested for the decolourization of one azo dye. The efficiency of the PL/H2O2 process in a batch reactor under different parametric values: dye concentration, pH, H2O2 and salt doses was followed by spectrophotometry and fitted to first-order kinetics; and several degradation products were detected. In the PL/H2O2 process, decolourization rates increased at low dye concentrations and high H2O2 doses, were pH-dependent and were inhibited by the addition of NaCl, Na2SO3 or Na2CO3. More than 50 % decolouration was achieved with the PL/H2O2 process for both dyes after applying 54 J/cm2 (25 light pulses). The PL/H2O2/ferrioxalate process achieved > 95 % decolouration for Methyl orange when applying 21 J/cm2 (10 pulses); that level of energy can be supplied by PL commercial systems in nine and four seconds respectively. No known toxic degradation products were detected. Results show that a PL/H2O2 process has potential to be used for the efficient degradation of dyes from wastewater. Furthermore, the efficacy of this process can be improved by the use of ferrioxalate. PL technology could become an alternative light source to contribute to decrease the environmental impact of wastewater produced by the dyeing industry.
关键词： pulsed light,ferrioxalate,advanced oxidation process,azo dye,wastewater remediation
更新于2025-09-19 17:15:36
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Spinel oxide ZnCr2O4 incorporated with ZnS quantum dots for application on visible light driven photocatalyst Azo dye degradation
摘要： Azo dyes, a kind of synthetic dye stuff, have a wide range of applications in textile, leather, food and printing industries, but it causes adverse health effects to human beings and to the ecosystem. Herein, we report the photocatalytic degradation of methyl orange dye, by using ZnS/ZnCr2O4 nanohybrid sample. The samples were prepared by simple precipitation process and characterized in order to investigate its crystallinity, morphology, functional group, photophysical properties, elemental composition and mapping. The amino acid capped ZnS/ZnCr2O4 nanohybrid show enhanced photocatalytic properties in the photodegradation of azo dye, compared to that of bare ZnS QDs and ZnCr2O4 nanoparticles. The nanohybrid remain unaffected after four cycles of azo dye degradation. The enhanced performance might be due to the formation of interface between ZnS QDs and ZnCr2O4 nanoparticles. The methionine capped ZnS/ZnCr2O4 nanohybrid provide a new hope to develop an efficient and commercializable photocatalyst with improved efficiency.
关键词： Azo dye,Quantum dots,Photocatalytic activity,Spinel oxide
更新于2025-09-16 10:30:52
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Improvement of the Degradation of Methyl Orange Using a TiO2/BDD Composite Electrode to Promote Electrochemical and Photoelectro-Oxidation Processes
摘要： Electrophoretic deposit of titanium dioxide (TiO2) was carried out over a boron doped diamond plate of 2 cm2, annealing at 350 °C to produce binary TiO2/BDD composite electrode. The composite was characterized by scanning electron microscopy (SEM) and linear sweep voltammetry (LSV) response. N,N-dimethyl-p-nitrosoaniline (RNO) was used as a probe molecule for the detection of free radicals (?OH) during the oxidation of water in phosphate buffer (pH 4) solution; at the TiO2/BDD/hv composite, an apparent first-rate kinetic constant of kobs = 0.1314 min-1 was observed. Afterwards, the composite electrode was applied to degrade 40 and 100 mg L-1 of a typical azo dye methyl orange (MO) via electrochemical process, such as: electro-oxidation (EO) and photoelectro-oxidation (PEO) under 25, 75 and 125 mA cm-2 current density (j); the PEO tests were performed using a UVA lamp at 365 nm. Results showed that the discoloration in the PEO process was larger than in the EO process, 96 and 100 %, respectively. Chemical Oxygen Demand (COD) was tested to evaluate the degradation. Hydroxylated derivatives were identified by means of mass spectroscopy during the PEO of MO in a TiO2/BDD/hv composite electrode.
关键词： TiO2/BDD composite,electrochemical process,hydroxyl radical formation,azo dye,water treatment
更新于2025-09-04 15:30:14