Decolorization Of Methyl Orange Research Articles

One-Step and Ligand-Free Modification of Au Nanoparticles on Highly Ordered TiO2 Nanotube Arrays for Effective Photoelectrocatalytic Decontamination

Photoelectrocatalytic (PEC) process has attracted much attention in the field of the decontamination of drinking water and wastewater due to its environmental friendliness and considerable efficiency. As a promising class of PEC materials, Au/TiO2 has been focused by researchers for a long time. Nevertheless, it is still difficult to synthesize uniform Au/TiO2 composites without the use of surface ligands, which may hinder the understanding of their intrinsic PEC properties. In this work, ligand-free Au/highly ordered TiO2 nanotube arrays (Au/hoTiO2 NTs) with high homogeneity were prepared successfully by carefully controlling the synthesis conditions. The physical and chemical properties of Au/hoTiO2 NTs with different Au contents were characterized by scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy, electrochemical impedance spectroscopy, life-time of photogenerated electrons, decolorization of methyl orange (MO) and photocurrent...

Efficient and synergistic decolourization and nitrate removal using a single-chamber with a coupled biocathode-photoanode system

With the continuous development of the chemical industries, synergistic removal of carbon and nitrogen contaminants has drawn much attention. In this work, a novel strategy for the synergistic removal of methyl orange (MO) and nitrate was developed in a single reactor by combining a TiO2/g-C3N4 nanosheet/graphene photoanode and denitrifying biofilm cathode. Under xenon light illumination, the photocatalytic MO decolorization rate exceeded 90% (the initial concentration of MO was as high as 100 mg·L−1) with a biocathode potential bias of −0.5 V vs Ag/AgCl; additionally, the decolourization rate apparently followed first-order kinetics with a constant of 0.11 ± 0.02 h−1. The improved MO decolourization rate was mainly because the biocathode effectively enhanced the charge separation of the photogenerated charge at the TiO2/g-C3N4 nanosheet/graphene photoanode interface. In the meantime, the effluent nitrate was lower than 1 mg·N·L−1 at a biocathode potential of −0.5 V vs Ag/AgCl. The results indicated that the coupled biocathode-photoanode system could serve the purpose of simultaneously degrading MO and accomplishing nitrate reduction. Considering the sustainability of sunlight and the use of a biocathode, the coupled biocathode-photoanode system is a promising alternative for the simultaneous removal of biorefractory organics and nitrate.

ZnO-assisted synthesis of multilayered Cu2(OH)3NO3 nanoplates and application removal of methyl orange

A class of well-defined Cu2(OH)3NO3 nanoplates with multilayered structure is successfully synthesized using ZnO and Cu(NO3)2 aqueous solution as precursors via metal oxide assisted route. Controlled experiments show that the Cu2(OH)3NO3 is developed from nanoparticles, ultrathin nanoplates to multilayered nanoplates with shape tips. Interestingly, the as-obtained Cu2(OH)3NO3 with well-defined nanoplate structure exhibits outstanding catalytic degradation capability towards methyl orange (MO) in the dark at room temperature. Impressively, the Cu2(OH)3NO3/ZnO composites display approximately 97% of MO decolorization within 20 min. Moreover, the Cu2(OH)3NO3/ZnO composites also show excellent stability.

The decolorization of methyl orange by persulfate activated with natural vanadium-titanium magnetite

Magnetite activating persulfate to produce sulfate radicals was received immense importance for its potential to destroy organic pollutants in wastewater. Herein, the Vanadium Titanium Magnetite (abbreviated as VTM) was characterized and applied in treatment of Methyl Orange (abbreviated as MO) pollutants containing solution for its availability and low cost, which exhibited its ideal activity in decolorization performance. The effects of initial pH, temperature, MO initial concentration, VTM dosage and PDS dosage on MO decolorization efficiency were all investigated through batch decolorization studies. MO is degraded by SO4− which is produced by activation of persulfate with Fe (II) provided by VTM. The MO decolorization rate (%) was increased from 75.20% to 97.82% with the VTM dosage increased from 1 g/L to 4 g/L and increased from 11.94% to 98.73% with the PDS concentration varied from 0 to 16 mM. When VTM or PDS continued to increase, MO decolorization rate decreased, which due to the mutual quenching of SO4− and the consumption of SO4− by Fe2+ and S2O82−.This study would create a lower cost approach for the decolorization of Methyl Orange containing wastewater activated by the VTM, which was a kind of low cost and available catalyst.

High-rate anaerobic decolorization of methyl orange from synthetic azo dye wastewater in a methane-based hollow fiber membrane bioreactor

Anaerobic biological techniques are widely used in the reductive decolorization of textile wastewater. However, the decolorization efficiency of textile wastewater by conventional anaerobic biological techniques is generally limited due to the low biomass retention capacity and short hydraulic retention time (HRT). In this study, a methane-based hollow fiber membrane bioreactor (HfMBR) was initially inoculated with an enriched anaerobic methane oxidation (AOM) culture to rapidly form an anaerobic biofilm. Then, synthetic azo dye wastewater containing methyl orange (MO) was fed into the HfMBR. MO decolorization efficiency of ∼ 100 % (HRT = 2 to 1.5 days) and maximum decolorization rate of 883 mg/L/day (HRT = 0.5 day) were obtained by the stepwise increase of the MO loading rate into the methane-based HfMBR. Scanning electron microscopy (SEM) and fluorescence in situ hybridization (FISH) analysis visually revealed that archaea clusters formed synergistic consortia with adjacent bacteria. Quantitative PCR (qPCR), phylogenetic and high-throughput sequencing analysis results further confirmed the biological consortia formation of methane-related archaea and partner bacteria, which played a synergistic role in MO decolorization. The high removal efficiency and stable microbial structure in HfMBR suggest it is a potentially effective technique for high-toxic azo dyes removal from textile wastewater.

Decolorization of methyl orange by MnO2/organic acid system: The role of Mn(III)

Decolorization of methyl orange (MO) by MnO2 was investigated with and without small molecules of organic acids such as formic acid. It was found that the decolorization could be significantly improved by MnO2 with the assistance of organic acids. The effect of various conditions was investigated on MO decolorization by using different crystal types of MnO2 and changing the types of organic acids. One of the optimum treatment conditions was δ-MnO2/formic acid system, which led to the removal efficiency of 90.6% at 30 min. The pseudo-second-order kinetic rate constant of δ-MnO2/formic acid was 0.1626. A reasonable decolorization mechanism involving Mn(III) species was proposed and the mechanism was validated by simple detection of ionic species such as, Mn(II) and Mn(III) during the reaction. The δ-MnO2/formic acid process designed here may lead to a new advanced oxidation technology based on the in-situ generation of active Mn(III) species and their ability for oxidation.

Biogenic synthesis of PdNCs embedded α-Fe2O3 microspheres using Myrtus cumini L. leaf extract and a Box-Behnken optimization of its Fenton-like catalytic activity

<p>Microspheres (MSs) of paramagnetic iron oxide (α-Fe2O3) embedded with palladium nanocubes (PdNCs) were biosynthesized using Myrtus cumini L. leaf extract. The synthesized PdNCs embedded α-Fe2O3 microspheres were characterized using FTIR, XRD and SEM/EDX. The FTIR spectrum of the Myrtus cumini L. leaf extract confirmed the presence of phenol, ester and amine groups that were involved in the bio-reduction of PdCl2 to PdNCs. SEM/EDX revealed that the PdNCs with size range of 15–250 nm were present on the surface of the synthesized microspheres. Box-Behnken Design (BBD) was employed for optimization of Methyl Orange (MO) decolorization using α-Fe2O3MSs and PdNCs embedded α-Fe2O3MSs at pH (1, 2 and 3), catalyst dosage (1, 3 and 5 g L-1) and reaction irradiation time (30, 60 and 90 min). It was found that PdNCs embedded α-Fe2O3MSs had maximum decolorization of 96.56 % at pH 1.72, catalyst dosage 2.69 g L-1 and irradiation time 68.34 min.</p>

Perbandingan Efektivitas Dekolorisasi Fotokatalitik Metilen Biru dan Metil Jingga Menggunakan Semikonduktor ZnO pada Variasi pH

The comparison of photocatalytic decolorization of Methylene Blue and Methyl Orange using ZnO Semiconductor under UV-LED radiation has been studied at varied pH. ZnO have been synthesized using co-precipitation method. The Scanning Electron Microscopy (SEM) result showed that the synthesized ZnO has a hexagonal structure with the particle size range 0.125 to 0.5 µm. The BET isotherm characterization showed the synthesized ZnO has a specific surface area (SBET), mesoporous volume and micropore volume of 60.20 m2/g, 0.541 cm3/g and 0.02 cm3/g, respectively. The observation of the effect of pH to the photocatalytic activity showed that the highest removal percentage occurred at pH 9 with the value of 95.64% for methylene blue and occurred at pH 3 with the value of 6.236% for methyl orange.

Perbandingan Efektivitas Dekolorisasi Fotokatalitik Metilen Biru dan Metil Jingga menggunakan Semikonduktor ZnO pada Variasi pH

The comparison of photocatalytic decolorization of Methylene Blue and Methyl Orange using ZnO Semiconductor under UV-LED radiation has been studied at varied pH. ZnO have been synthesized using co-precipitation method. The Scanning Electron Microscopy (SEM) result showed that the synthesized ZnO has a hexagonal structure with the particle size range 0.125 to 0.5 µm. The BET isotherm characterization showed the synthesized ZnO has a specific surface area (SBET), mesoporous volume and micropore volume of 60.20 m2/g, 0.541 cm3/g and 0.02 cm3/g, respectively. The observation of the effect of pH to the photocatalytic activity showed that the highest removal percentage occurred at pH 9 with the value of 95.64% for methylene blue and occurred at pH 3 with the value of 6.236% for methyl orange.Â

Synthesis of polymer-supported Brønsted acid-functionalized Zn–porphyrin complex, knotted with benzimidazolium moiety for photodegradation of azo dyes under visible-light irradiation

A polymer-supported Bronsted acid-functionalized Zn–porphyrin complex, knotted with benzimidazolium moiety (PSBAZnPP), has been synthesized and characterized by Fourier transform nuclear magnetic resonance (FT-NMR) and Fourier transform infrared spectroscopy (FTIR). The thermal stability was determined by thermogravimetric analysis (TGA), and surface morphology and elemental composition were investigated by scanning electron microscopy and energy-dispersive spectroscopy (SEM/EDAX). The heterogeneous PSBAZnPP showed high efficacy as a photocatalyst for degradation of azo dyes, such as methyl red (MR), methyl orange (MO) and Congo red (CR), in the presence of visible-light irradiation at ambient condition using atmospheric air/H2O2. The concentration of the dyes was measured by UV–visible spectroscopy, and the degradation of the dyes was confirmed by GC–MS analysis. Further decolorization and degradation of MO were confirmed by using ultra-high-pressure liquid chromatography (UPLC). The optimum degradation was achieved by adding 10 mg catalyst for all azo dyes for 60 min in the presence of air. The effect of scavengers was studied to indicate the most active species generated during photocatalysis. PSBAZnPP furnished a good response toward the photodegradation of MR, MO and CR under optimized conditions. Finally, the mechanism of photocatalytic degradation process was suggested. Relevant active species produced in the PSBAZnPP/H2O2 or PSBAZnPP/air system under visible light were recognized by using different types of scavengers, viz. EDTA, p-benzoquinone (PBQ), terephthalic acid (TPA), sodium azide and sodium nitrate, for determination of formation of holes, $${\text{O}}_{2}^{ \cdot }$$, $${\text{OH}}^{ \cdot }$$, $${}^{1}{\text{O}}_{2}$$ and an aqueous electron (e−), respectively. The comparative acidity of the synthesized PSBAZnPP catalyst was measured using UV–Vis and then equated to relations of the Hammett value (H0). The efficiency of catalyst correlates with a considerable proton level required for degradation of organic dyes.

Characterization and photocatalytic activity of Y-doped BiFeO3 ceramics prepared by solid-state reaction method

Singe phase bismuth ferrite doped by yttrium (Bi1−xYxFeO3, x = 0, 0.05, 0.1, 0.15, 0.2 and 0.25) was synthesized by solid-state reaction followed by sintering. Their structural, morphological, ferroelectric, magnetic and optical properties were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), vibrating sample magnetometer (VSM) and UV–visible spectrophotometry. Rhombohedrally-distorted perovskite structure of bismuth ferrite was confirmed by XRD analysis and Rietveld refinement. Microstrain and crystallite size were analyzed using Williamson-Hall model. SEM micrographs showed agglomerated particles. The doping of yttrium into the BiFeO3 (BFO) lattice enhanced the ferroelectric and magnetic properties and the leakage current density was reduced. The energy band gap was also decreased by increasing yttrium content, leading to an enhancement of light absorption capability. The photocatalytic activity of all samples has been evaluated by the decolorization of methyl orange (MO) under visible light irradiation. The results indicated that increasing the concentration of yttrium into the BiFeO3 (BFO) structure improved the photodegradation up to 71%.

Preparation of Biomass Activated Carbon Supported Nanoscale Zero-Valent Iron (Nzvi) and Its Application in Decolorization of Methyl Orange from Aqueous Solution

The nanoscale zero-valent iron (nZVI) has great potential to degrade organic polluted wastewater. In this study, the nZVI particles were obtained by the pulse electrodeposition and were loaded on the biomass activated carbon (BC) for synthesizing the composite material of BC-nZVI. The composite material was characterized by SEM-EDS and XRD and was also used for the decolorization of methyl orange (MO) test. The results showed that the 97.94% removal percentage demonstrated its promise in the remediation of dye wastewater for 60 min. The rate of MO matched well with the pseudo-second-order model, and the rate-limiting step may be a chemical sorption between the MO and BC-nZVI. The removal percentage of MO can be effectively improved with higher temperature, larger BC-nZVI dosage, and lower initial concentration of MO at the pH of 7 condition.

Facile synthesis of n-ZnO @ p-CuO nanocomposite for water purification enhanced decolorization of methyl orange

UV light-driven heterogeneous photocatalytic process has been broadly studied as a favorable technique for decolorization of pollutants present in organic wastewater. Herein, we have refined the ZnO@CuO nanocomposite enhanced UV light-driven photodecolorization process using methyl orange (MO) dye as the exemplary photocatalyst pollutant system. We found that the photocatalytic decolorization rate of methyl orange dye was prominently enhanced by ZnO@CuO nanocomposite, and the efficiency also subsequently had increased. The quality crystalline powder of ZnO@CuO nanocomposite was synthesized by adapting hydrothermal method owing to the conventionality and simplified taxonomy. The resulting powders were characterized to study their structural, morphological and optical properties. XRD patterns disclosed the formation of ZnO@CuO nanocomposite with favorable crystalline quality. High resolution scanning electron microscope and-transmission electron microscope images showed that the spherical morphology of nanorods had formed. The stretching and vibration of chemical bonds of the materials were further certified by FTIR spectroscopy. The strong UV emission peaks were detected and the energy gap of the composite had been found as 3.8 eV. Raman spectroscopy was used as an effectual way to assess purity, crystallinity and local vibrations of the sample. The lower PL intensity specified the restricted or slower recombination rate and higher PL intensity designated a faster recombination rate. Investigations of temperature dependent dielectric property of ZnO@CuO nanocomposite results were also discussed. The photocatalytic contaminant removal efficiency of the heterojunction ZnO@CuO nanocomposite over methyl orange was obtained as 91% under 70 min irradiation of the UV light. The present work gives a hopeful way to achieve ZnO@CuO nanocomposite heterojunction for the eco-friendly application in contaminant water purification.

Photo-Fenton process in Co(II)-adsorbed admicellar soft-template on alumina support for methyl orange degradation

Abstract In the present work, a novel approach has been made to prepare a new catalyst for Fenton-type degradation of dye. In the first step alumina is modified with sodium dodecyl sulfate (an anionic surfactant). Under suitable conditions the surfactant forms bilayer (admicelle) on alumina surface. The surfactant-modified alumina (SMA) can adsorb metal ions such as Co(II), Fe(II), Cu(II), Mn(II) and Ni(II) on its surface. Among all the metal ions Co(II) shows the best catalytic activity when supported on SMA. The newly formed catalyst is named as Co-SMA. In this report, we described the degradation of methyl orange (MO) under heterogeneous photo-Fenton condition by application of Co-SMA as the catalyst and in the presence of H2O2 and visible light. Effect of various independent variables such as dose of catalyst, initial concentration of the dye, H2O2 concentration, intensity of visible light, pH have been studied. The process parameters were optimized by response surface methodology (RSM) approach. Under the optimum conditions of 30 mg/L MO, 29.92 g/L Co-SMA, 37.9 mM H2O2 and pH 4.31, the maximum response for MO decolorization efficiency was 94.79%.

Bio-decolorization and novel bio-transformation of methyl orange by brown-rot fungi

An investigation was conducted to assess the ability of three species of brown-rot fungi to decolorize and transform methyl orange dye. Methyl orange was decolorized in a potato dextrose agar medium by Fomitopsis pinicola, Gloeophyllum trabeum, and Daedalea dickinsii at different concentrations of 50, 75, and 100 mg L−1. Based on the values of the decolorization index, the highest methyl orange decolorization was found approximately 91% by F. pinicola, followed by D. dickinsii and G. trabeum of 82% and 76%, respectively, at a concentration of 50 mg L−1. F. pinicola had the highest methyl orange transformation with percent decolorization values of approximately 97%, followed by D. dickinsii and G. trabeum of 93% and 67%, respectively, after a 14-day incubation period in potato dextrose broth. F. pinicola transformed methyl orange into six metabolic products: compounds 3, 6, 7, 8, 9, and 10, while G. trabeum transformed methyl orange into five metabolic products: compounds 1, 2, 3, 4, and 5. Among brown-rot fungi, D. dickinsii had more metabolic products, with compounds 3, 4, 6, 11, 12, 13, 14, 15, 16, 17, and 18. Based on the identification of metabolic products, novel bio-transformation was proposed that brown-rot fungi initially transformed methyl orange via three pathways: (1) demethylation, (2) desulfonylation, and (3) hydroxylation. This study indicated that brown-rot fungi can be used to decolorize and transform methyl orange dye as well as proposed novel bio-transformation of methyl orange by brown-rot fungi.

Heterogeneous sonocatalytic degradation of an anionic dye in aqueous solution using a magnetic lanthanum dioxide carbonate-doped zinc ferrite-reduced graphene oxide nanostructure

We report herein the sonochemical synthesis of a lanthanum dioxide carbonate (La2O2CO3) and zinc ferrite (ZnFe2O4)-loaded reduced graphene oxide (LZF-rGO) nanoheterostructure for ultrasound (US)-assisted degradation of methyl orange (MO) from water. The MO was chosen as a model organic dye due to its toxicological and biodegradable-resistant properties. The LZF-rGO catalyst was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results of characterizations confirmed successful synthesis of sonocatalyst. Among different removal systems, US/LZF-rGO displayed outstanding sonodegradation performance for degradation of MO. The maximum removal efficiency of 75.9% was achieved using 0.2 g/L sonocatalyst, 20 mg/L MO, and 0.71 W/cm2 US power intensity for 65 min. MO can be partially adsorbed on LZF-rGO but mostly sonodegraded by reactive radical species. The reaction conditions were optimized by investigating the effect of key operating parameters, including the sonocatalyst dosage, initial MO concentration, US power intensity, presence of inorganic salts, and use of an enhancer, on the decolorization of MO. The degradation intermediates produced from MO during the sonocatalytic process were identified by UPLC®/MS-MS, and possible mechanism and pathway for the degradation of MO in the US/LZF-rGO system were also proposed. Reusability experiments with this sonocatalyst revealed a less than 10% drop in the degradation efficiency after four adsorption–desorption cycles.

Direct synthesis of bismuth nanosheets on a gas diffusion layer as a high-performance cathode for a coupled electrochemical system capable of electroreduction of CO2 to formate with simultaneous degradation of organic pollutants

A coupled electrochemical system (CES) for the electroreduction of CO2 to formate (ERCF) and simultaneous degradation of organic pollutants is a promising approach for CO2 conversion. Cathode material is a critical component of CES. However, the poor performance and complexity of synthesis limit its real application. Here, we report a Bi-based binder-free gas diffusion electrode (EBGDE) as a high-performance cathode for CES. The EBGDE was fabricated via direct electrodeposition of Bi nanosheets on a gas diffusion layer. By optimizing the deposition time of Bi nanosheets, a good Faraday efficiency (91.46 ± 6.58%) and formate production rate (1849.96 ± 127.69 μmol m−2 s−1) were obtained. Simultaneously, the methyl orange decolorization efficiency and chemical oxygen demand removal efficiency reached 100% and 55.25 ± 6.87%, respectively. This performance towards ERCF is better than recently reported ERCF electrodes. It probably results from the excellent performance of associated Bi-nanosheets catalysts, a high electroactive surface area, as well as fast electron transfer in the EBGDE. This work offers design rules to fabricate high-performance cathode materials for CES in industrial applications.

Mechanistic of photocatalytic decolorization and mineralization of methyl orange dye by immobilized TiO2/chitosan-montmorillonite

The mechanistic of photocatalytic decolorization and mineralization of methyl orange (MO) dye have been successfully studied using immobilized titanium dioxide/chitosan-montmorillonite (TiO2/CS-MT), a combination of TiO2 as the top layer and CS-MT as the sub-layer on a glass plate. The immobilized CS-MT film was selected over the CS film since the former adhered stronger and swelled less than the latter which showed its favorability in the aqueous medium. This bilayer photocatalyst operated via a simultaneous occurrence of adsorption of MO dye from the CS-MT layer and photocatalytic degradation by TiO2 layer. The bilayer photocatalyst could remove the MO dye from the solution 3 times faster than the single TiO2 within 90 min of irradiation under a UV–vis lamp due to strong adsorption of MO by the CS-MT sub-layer. The mechanistic study revealed that the degradation occurred via the e−/O2- route while the LC–MS analysis suggested the possible degradation pathway of MO dye. It was found that the eluent used for separation of compounds in the LC–MS analysis influenced the intermediates detected for which two degradation mechanisms were proposed.

Enhanced degradation performance of organic dye over the reduced double perovskite compound Sr2CaWO6 under visible light irradiation

We investigated the effects of heat treatment in reduced atmosphere on the chemical states and photocatalytic performance of a typical double perovskite compound, Sr2CaWO6. The pristine Sr2CaWO6 powders, prepared with a simple sol-gel method, crystallize in a monoclinic structure. The as-prepared Sr2CaWO6 powders were treated at 900, 1000 and 1100 °C in flowing H2 atmosphere to obtain photocatalyst samples. The main phase composition of the reduced samples is in accordance with that of the pristine sample. X-ray photoelectron spectra analysis confirmed that the reduced treatment at 1100 °C introduced a great quantity of sub-stoichiometric species (including W5+ or W4+, O− or O atom) and oxygen vacancies in the photocatalyst. The first principle calculations were performed to study the electronic structures of the Sr2CaWO6 with the intrinsic defects. The black sample treated at 1100 °C can absorb visible light efficiently, and exhibits superior photocatalytic activity and stability on degradation of methyl orange. The main active species for the decolorization of methyl orange are ·O2− and h+ radicals.

Enhanced decolorization of methyl orange by Bacillus sp. strain with magnetic humic acid nanoparticles under high salt conditions

In this study, magnetic humic acid (MHA) nanoparticle was prepared and confirmed the enhancement on reduction of azo dyes under high salt concentration. The anaerobic growth of the strain Bacillus sp. on quinones makes the biogenic hydroquinone feasible, and the latter was proven to reduce the azo dyes stoichiometrically. This in-situ reversibly oxidation and reduction of MHA acts as electron shuttle to catalyze the biotic reduction of the azo dyes. The biodegradation efficiencies in batch experiments and sequencing batch reactor with MHA were increased by 1.5–2.5 times as compared to that of control without the catalyzer. Moreover, the negligible leaching of HA under various environmental conditions suggests the robustness of the coating of HA on Fe/O surface. These results indicated that the as-prepared MHA could be used as redox mediator to accelerate the extracellular electron transfer, which is of great environmental significance for the removal of hazardous compounds.