Decolorization Of Methyl Orange Research Articles

Facile Preparation of Granular Copper Films as Cathode for Enhanced Electrochemical Degradation of Methyl Orange.

In this paper, granular copper films (GCFs) were prepared through electrodeposition in CuSO4 solution containing triethanolamine, and the films were used as electro-Fenton-like cathodes for degradation of methyl orange (MO). The effects of triethanolamine concentration, pH value, current intensity and temperature on the morphology of the films, as well as the MO decolorization ratio (DR), were investigated in detail. Results show that when the concentration of triethanolamine is 0.2 wt%, the prepared GCF exhibits the best performance. Under room temperature and neutral conditions, no external O2 or catalyst, MO is completely decolorized after 240 min. Compared with the commonly used carbon cathode, the GCF cathode can increase the MO decolorization rate by approximately 70.9%. The kinetics of the electrochemical degradation reaction is also discussed.

Ferric ion-ascorbic acid complex catalyzed calcium peroxide for organic wastewater treatment: Optimized by response surface method

Hydrogen peroxide (H2O2) disproportionation, iron precipitation, and narrow pH range are the drawbacks of traditional Fenton process. To surmount these barriers, we proposed a ferric ion (Fe3+)-ascorbic acid (AA) complex catalyzed calcium peroxide (CaO2) Fenton-like system to remove organic dyes in water. This collaborative Fe3+/AA/CaO2 system presented an obvious improvement in the methyl orange (MO) decolorization, and also effectively eliminated other dyes. Response surface method was employed to optimize the running parameters for this coupling process. Under the optimized arguments (2.76 mmol/L Fe3+, 0.68 mmol/L AA, and 4 mmol/L CaO2), the MO removal achieved 98.90% after 15 min at pH 6.50, which was close to the computed outcome of 99.30%. Furthermore, this Fenton-like system could perform well in a wide range of pH (3–11), and enhance the H2O2 decomposition and Fe ions recycle. The scavenger experiment result indicated that hydroxyl radical, superoxide anion free radical, and singlet oxygen were acted on the dye elimination. Moreover, electron spin resonance analysis corroborated that the existences of these active species in the Fe3+/AA/CaO2 system. This study could advance the development of Fenton-like technique in organic effluent disposal.

Experimental and theoretical investigation of a homogeneous Fenton process for the degradation of an azo dye in batch reactor

The aim of this work was to study the homogeneous oxidation process of Fenton for the decolorization of methyl orange (MO) using experimental design methodology. The efficiency of this process was evaluated according to the effect of each of the most influential parameters such as concentrations of Fe2+, H2O2, MO and the pH, also their combined effects using three responses: the decolorization yield (R), the amount of dye removed per gram of catalyst (Q) and the time required to reach steady state (tss). The ANOVA showed that about 99% of the variations in R and Q responses and 92% of the tss response could be explained by these linear models with interactions. To ensure maximum yield of MO degradation (100%) with minimum residence time (less than 1 min) in the batch reactor, the Fenton process should be carried out in MO diluted medium ([MO] = 2 mg/L) and under the following optimal conditions: [H2O2] = 3.53 mM, [Fe2+] = 0.067 g/L and pH 2. These conditions were verified experimentally, enabling these three regression equations to be used for modeling the Fenton process and predicting future responses.

Titania Modified Silica from Sugarcane Bagasse Waste for Photocatalytic Wastewater Treatment

Photocatalytic oxidation is one of the technologies to overcome pollution that can be applied for air and water purification. TiO2 has been widely used as a photocatalyst, however, several disadvantages of TiO2 including low absorption of visible or solar radiation, rapid recombination of electron and hole as well as low stability limits its practical applications especially for wastewater treatment. Thus, to overcome this problem, this study aims to develop highly adsorbent photocatalyst using TiO2/SiO2 composites with sugarcane bagasse waste act as SiO2 source. The experimental results show that the photocatalytic performance of TiO2/SiO2 composite in the decolorization of methyl orange exhibits three-fold enhancement compared to neat TiO2. Several catalyst characterizations were obtained including X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray fluorescence (XRF). Characterization data show that a phase transformation was obtained from amorphous to crystalline phase by increasing TiO2 content. These results proved that the feasibility of SiO2 from sugarcane bagasse waste coupled with TiO2 can be utilized for wastewater degradation.

Development of highly active, chemically stable and recyclable magnetic nanophotocatalyst based on plasmonic silver nanoparticles and photosensitive trans‐3‐(trans‐4‐imidazolyl) acrylic acid molecules

This study relates to the preparation of a novel nanophotocatalyst comprising of plasmonic silver nanoparticle, photosensitive trans‐3‐(trans‐4‐imidazolyl) acrylic acid (T3TTIA) and superparamagnetic iron oxide nanoparticles (SPION). This heterogeneous nano‐photocatalyst has been synthesized via hydrothermal route where T3TTIA works as a capping agent and linker for SPION and plasmonic Ag NPs, respectively. Structural, morphological, thermal, magnetic, optical, and catalytic properties have been analyzed in detailed. The spinel cubic type structure of nanocrystals of SPION and silver has been confirmed by XRD analysis. XPS analysis has confirmed the presence of Ag0, Fe3O4, and integral functional group. The strong chemical interaction of localized surface plasmonic Ag nanoparticles and SPION with photosensitive T3TIAA molecule has been revealed by both the IR and XPS analysis. The shape of the final products has been observed as spherical with average particle size of 12 ±0.8 nm (with low degree of agglomeration) as analyzed by scanning electron microscope (SEM) and high resolution transmission electron microscope (HR‐TEM). The superparamagnetic nature and high thermal stability of the products have been revealed by vibrating sample magnetometry (VSM) and thermogravimetric (TG) analysis, respectively. UV‐visible spectrophotometry analysis has confirmed the maximum absorbance peak at ~420 nm, indicates as the characteristic peak of surface plasmon resonance (SPR) for silver nanoparticles with a band gap value of 1.43 eV. Furthermore, Brunauer−Emmett−Teller (BET) analysis has demonstrated mesoporous characteristic of the product which follows type IV isotherms with the average surface area and pore size as 250.492 m2/g and 6.1442 nm, respectively. The potential catalytic applications of the as‐prepared nanocatalysts have been explored for the decolorization of methyl orange (MO), methylene blue (MB), and photo‐reduction of 4‐nitrophenol (4‐NP) under both Visible and UV light irradiations. The catalytic activity of the as‐prepared nanocatalyst has been compared with the recent reported magnetic nano‐catalysts. The SPION@T3TIAA‐Ag nanocatalyst has shown excellent catalytic behavior toward the treatment of the selected industrial dyes and organic pollutant with recovery and reusability capacity up to seven cycles without losing significant catalytic efficiency.

Continuous flowing electrocoagulation reactor for efficient removal of azo dyes: Kinetic and isotherm studies of adsorption

Abstract The electrocoagulation process is an effective and economical technology for the treatment of industrial wastewater. So, it is particularly important to develop an efficient electrocoagulation reactor. To this end, a novel electrocoagulation reactor is described to effectively remove azo dyes from aqueous solutions utilizing electrocoagulation, in which the electrode plate is bent. Continuous wastewater flows in the reactor will promote faster and more stable growth of flocs This paper took methyl orange as a study object. It was concluded that methyl orange decolorization rate was 92.35% under the optimal conditions while flat electrode under the same conditions of methyl orange decolorization rate was only 58.9%. The results meant that the second-order kinetic model was most in line with the experimental results, which indicated that the chemisorption mechanism controls the adsorption of methyl orange. Furthermore, the results showed that the Langmuir isotherm model was more in line with the experimental results, and showed that the experiment was single-layer adsorption on the adsorbent surface. Under the optimal conditions of the electrocoagulation process, electrode consumption is 0.2376 g, and the electrical energy consumption is 1.5925 KWh m−3 during a single operation.

Influence of Fe3+ ion doping on the luminescence emission behavior and photocatalytic activity of Fe3+, Eu3+-codoped TiO2 thin films

Abstract Thin films of Fe3+ doped TiO2:0.01Eu3+ nanoparticles were coated by sol-gel spin coating technique on glass substrates. The studies carried out by using X-ray Diffractometer, SEM-EDX, HRTEM, spectroscopic ellipsometer, Raman, EPR, UV–Vis, and fluorescence spectrometer techniques. The crystalline structure and phase formation of Fe doped TiO2:0.01Eu3+ nanoparticles were investigated using X-ray Diffractometer. The HRTEM pictures of 3%, and 5% Fe doped TiO2:0.01Eu3+ films confirmed that the particle size is about 11 nm and 9.5 nm respectively. Raman spectroscopy was used to study the phase identification and vibrational modes present in Fe, Eu codoped TiO2 films. The band gap declined with cumulative amount of Fe3+. The EPR analysis endorses that the Fe3+ ions are successfully doped in the lattice of Titania by replacing Ti4+ ions and formation of oxygen vacancies and Ti3+ sites. With 393 nm excitation, the Fe doped TiO2:0.01Eu3+ nanoparticles show characteristic photoluminescence in the visible range. The strong luminescence emission at 614 nm is related to the 5D0 → 7F2 ED transition. The emission peak intensity declined with an increase in the amount of Fe3+. J–O and radiative parameters of Fe doped TiO2:0.01Eu3+ films obtained from the emission spectra. These nanophosphor films having significant CIE chromaticity coordinate (x, y) values with high color purity might have potential applications in solid-state display devices. The photocatalytic activity (PCA) of Fe, Eu codoped TiO2 nanostructured films were estimated using decolorization of methylene blue (MB) and methyl orange (MO). Fe, Eu codoped TiO2 films exhibit strong photocatalytic performance than undoped and single doped TiO2 films. The degradation efficiencies significantly increase with an increase in Fe3+ doping concentration reached maximum at 3%Fe doping and then reduces gradually at high concentrations due to the formation of recombination centers for charge carriers at a higher amount of Fe doping.

Decolorization and Mycoremediation of Methyl Orange using Beauveria bassiana

The purpose of this study is to evaluate the application of Beauveria bassiana in the decolorization and degrade of Methyl Orange (MO) as a model sulfonated azo dye from aqueous solution. B. bassiana was acclimated to higher concentration of MO dye (25 – 250 mg/L) in MSM after repeated sub-culturing. B. bassiana could completely decolorize of MO in a large variety up to 100 mg/L of MO concentration, at 28 °C and pH 8. This study showed that methyl orange is fully decolorized by Beauveria bassiana at optimized operational conditions within 7 days of incubation period.

Nanocomposite of functionalized halloysite and Ag(0) decorated magnetic carbon dots as a reusable catalyst for reduction of dyes in water

A new magnetic, catalytic nanocomposite of Hal-MT-Cys-Ag/MNCD was fabricated and utilized for catalyzing reductive de-colorization of methyl orange and rhodamin B in aqueous media at room temperature. To prepare this material, Cl-functionalized halloysite nanoclay was successively reacted with melamine and 2,4,6-trichloro-1,3,5-triazine to furnish multi-nitrogen containing ligand on halloysite surface. Then, magnetic carbon dots were crafted through a facile method and decorated with Ag nanoparticles and cysteine to furnish Cys-Ag/MNCD species. The final nanocomposite was obtained via incorporation of this latter species onto functionalized halloysite. This new composite was characterized through the XRD, TEM, BET, FTIR, TGA, EDX, and mapping analyses. The catalytic experiments confirmed that low loadings of the Hal-MT-Cys-Ag/MNCD composite reduction of both dyes were performed in ~1 min. This material could also be readily collected from the reaction media magnetically and displayed excellent recyclability with a slight decrease in its activity of at most ~6% up to 8 cycles. The kinetic and thermodynamic study of de-colorization reactions emphasized high catalytic performances of the synthesized nanocomposite. More precisely, activation energy, enthalpy, and entropy were determined to be 48.15 kJ mol−1, 45.65 kJ mol−1, and -124.61 J mol−1 K−1; respectively for the methyl orange while the corresponding values for the rhodamine B were found to be 11.03 kJ mol−1, 8.53 kJ mol−1, and -249.93 J mol−1. K−1.

In-air proton beam irradiation induced radiolysis of methyl orange in aqueous solution

Proton irradiation induced radiolysis of methyl orange was investigated in aqueous solution with an in-air ion beam setup. 566–3024 keV energy protons were used for the irradiations of 1.6 mM aqueous methyl orange solutions, in the presence and absence of tert-butanol radical scavenger. The decoloration of methyl orange was followed by UV/vis spectrophotometry. It was found that the methyl orange can be efficiently decolorized in the applied energy range, caused by degradation processes. Furthermore, the efficiency of methyl orange radiolysis was found to be dependent on the applied proton energy. The irradiations were also carried out in the presence of 0.16 and 0.73 mol dm−3 tert-butanol using 3024 keV protons. It was found, that at lower concentration of radical scavenger the degradation was less efficient, while at higher concentration of the radical scavenger, interestingly, the degradation was more efficient when compared to the scavenger-less irradiation experiments. Initial G-values were determined for all ion energies and for different scavenger concentrations.

Purification, characterization, and crystal structure of YhdA-type azoreductase from Bacillus velezensis.

Azoreductases are being extensively investigated for their ability to initiate degradation of recalcitrant azo dyes through reduction of azo bonds. There is great interest in studying their diversity, structure, and function to facilitate better understanding and effective application. Current study reports azoreductase enzyme from Bacillus velezensis, which showed 69.5% identity to the Bacillus subtilis azoreductase YhdA. The enzyme was homotetrameric and molecular weight of each subunit was 20 kDa. It decolorized azo dyes with different structures. The Vmax for decolorization of congo red, methyl orange and methyl red was 14.7, 28.6, and 77.9 nmol/min/mg, respectively. The enzyme contained FMN as cofactor and used NADPH as the favored co-substrate. It was oxygen-insensitive, but the presence of reducing agents enhanced its activity, which is a new finding. The azoreductase expression in B. velezensis was found to be unaffected by addition of azo dyes, although azo dyes are known to induce azoreductase expression in few organisms. The enzyme was thermostable with melting temperature of 89.5°C and functioned in wide temperature range. Further, the enzyme was crystallized and its structure was solved. The structural basis of its functional attributes is discussed. In our knowledge, this is the first report on characterization of azoreductase enzyme from B. velezensis.

Decolorization, degradation and detoxification of carcinogenic sulfonated azo dye methyl orange by newly developed biofilm consortia.

Metabolites of azo dyes are often carcinogenic, teratogenic, mutagenic and recalcitrant in nature. In this study, four biofilm consortia such as C1 (Vitreoscilla sp. ENSG301, Acinetobacter lwoffii ENSG302, Klebsiella pneumoniae ENSG303 and Pseudomonas fluorescens ENSG304), C2 (Escherichia coli ENSD101, Enterobacter asburiae ENSD102 and E. ludwigii ENSH201), C3 (E. asburiae ENSD102, Vitreoscilla sp. ENSG301 and Bacillus thuringiensis ENSW401), and C4 (E. coli ENSD101, E. ludwigii ENSH201 and B. thuringiensis ENSW401) were applied to degrade and detoxify methyl orange (MO), a carcinogenic, sulfonated mono azo dye, used in textile dyeing industry worldwide. The consortia of C1, C2, C3 and C4 showed 97.30, 98.75, 99.51 and 99.29% decolorization, respectively in yeast extract peptone (YEP) broth containing 200 mg L−1 MO within 60 h of incubation in static condition. The optimum pH and temperature for decolorization was 7.0 and 28 °C, respectively. Some divalent metal ions including Mg2+, Ca2+, Zn2+ and Mn2+ could stimulate MO decolorization. UV–Vis spectral analysis showed that the absorption peak at 465 nm originated from the azo (N Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> N) bond was completely disappeared within 60 h of incubation. Fourier transform infrared spectroscopy (FTIR) results also revealed that several major peaks including azo bond peak at 1602.6 cm−1 are completely or partly vanished, deformed or shifted. Activities of azoreductase, NADH-DCIP reductase and laccase were significantly increased in the bacterial cells within 60 h of incubation in comparison to that of control (0 h). The chemical oxygen demand was incredibly reduced by 85.37 to 91.44% by these consortia. Accordingly, plant (wheat seed germination) and microbial (growth of the plant probiotic bacteria such as Pseudomonas cedrina ESR12 and Bacillus cereus ESD3 on biodegraded products) toxicity studies showed that biodegraded products of MO are non-toxic. Thus, all these consortia can be utilized in bioremediation of MO from wastewater for safe disposal into environment. To our knowledge, this is the first report on degradation and detoxification of MO from wastewater by bacterial biofilm consortia.

Decolorization of Methyl Orange using a Double-chamber Microbial Fuel Cell with the Use of Soil Microorganisms

In this study, the decolorization of methyl orange was carried out in a double chamber microbial fuel cell. Microbial fuel cells (MFC’s) have been widely studied using various materials and operating conditions, these bioelectrochemical devices that use exoelectrogenic bacteria as biocatalysts have shown great potential to oxidize a variety of substrates while simultaneously generating electricity. Soil microorganisms consisting of lactic acid bacteria, Saccharomyces, Rhizobium, Rhodopseudomonas, Rhodobacter, Actinomycetes, and fungi were obtained from a concentrated soil microbial inoculant. Comparatively, the results of the experiments showed that using titanium mesh, the open circuit voltage and the power density of the MFC in close-circuit condition were 1.005 V and 1.223 Wm−2 while using carbon fiber brushes, values were 0.992 V and 0.338 Wm−2. On the other hand, results also revealed that the system with carbon fiber brush electrodes is more effective in decolorizing methyl orange at a maximum of 78 percent removal efficiency. In 10 hours of continuous operation, the concentration of methyl orange reduced from 0.10-0.022 mM.

Effect of Sb5+ codopant ions on the ultraviolet photocatalytic activity of Fe3+-modified anatase

The presence of antimony in (x at% Fe3+ + x at% Sb5+):TiO2 powder samples containing equimolar amounts (0.15 ≤ x ≤ 1) of the dopant cations was accompanied by an increase in the reaction rate constant k of the decolorization of methyl orange. Nevertheless, the increase in the rate of this test reaction, consistent with a decrease in the number of charge balance oxygen vacancies VO imputable to the codoping with Sb5+, rapidly weakened with increasing x. This effect is accounted for by the increased number of Fe3+–VO associates slowing down the outward diffusion of VO vacancies and, consequently, their rate of annealing in the studied catalyst.

Enzymatic degradation of sulphonated azo dye using purified azoreductase from facultative Klebsiella pneumoniae.

Heterologously expressed and purified azoreductase enzyme from facultative Klebsiella pneumoniae was used to degrade sulphonated azo dye. Methyl orange (MO) was used as the model dye to study the azo dye decolorization potential of the purified enzyme at different conditions. The enzyme had maximum activity at 40 °C and pH 8.0. The enzyme was observed to be thermo-stable as some enzyme activity was retained even at 80 °C. The apparent kinetic parameters, i.e., appKm and appVmax, for azoreductase using MO as a substrate were found to be 17.18 μM and 0.08/min, respectively. The purified enzyme was able to decolorize approximately 83% of MO (20 μM) within 10 min in the presence of NADH. Thus, efficient decolorization of MO was observed by the purified enzyme. The recombinant enzyme was purified approximately 18-fold with 46% yield at the end of four steps of the purification process. Enzyme was present in a tetrameric structure as confirmed by the volume at which protein was eluted in gel filtration chromatography, and the monomeric molecular mass of enzyme was found to be 23 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The dye degradation efficiency of azoreductase cloned from Klebsiella pneumoniae and purified from recombinant Escherichia coli was observed to be much higher as compared with the efficiencies of the reported azoreductases from other bacterial strains. In the present study, we report the purification and characterization of the azoreductase cloned from Klebsiella pneumoniae and expressed in Escherichia coli.

Photoluminescence and photocatalytic activity of spin coated Ag+ doped anatase TiO2 thin films

Abstract Ag + doped TiO2 (Ag-TiO2) thin films were coated on glass substrates with different dopant concentrations (1%, 3%, 5% 7% and 10%) and were subsequently annealed at 550 °C. The crystalline structure and phase formation of Ag–TiO2 was examined using XRD. The HRTEM analysis of pure and 5% Ag doped TiO2 thin films was revealed that the particles are spherical in shape with sizes around 23.8 and 11.6 nm respectively. Raman spectrometer was also used to identify the phase formation and vibrational modes present in the prepared silver doped TiO2 coatings. EPR spectra confirm the presence of oxygen vacancies (Vo) and Ti3+ sites in the Ag–TiO2 thin films. With excitation at 325 nm, Ag doped TiO2 nanoparticles show characteristic photoluminescence (PL) corresponding to the visible spectral range. Ag doped TiO2 thin films showed enhanced photocatalytic behaviour due to their narrow band gap energy (3.17–2.75 eV), high surface area (85–231 m2/g), and a reduced luminescence. Among all the films 5% Ag–TiO2 film exhibited strong photocatalytic activity (PCA) and was estimated by visible light decolorization of methylene blue (MB) and methyl orange (MO).

Effect of cerium oxide doping on the photocatalytic properties of rutile TiO2 films prepared by spray pyrolysis

The spray pyrolysis is fast and simple method for deposition of CeO2 – rutile TiO2 coatings on stainless steel substrate. The coatings were deposited on stainless steel substrate and characterized by XRD, AFM, XPS, Raman, DRS and photoactivity test for methyl orange decolorization. Photoactivity of CeO2 – rutile TiO2 coatings increase with increasing CeO2 content up to 5 wt% and further increase of CeO2 content leads to decrease of photoactivity. Improvements of photoactivity originate from close contact between CeO2 and rutile TiO2 particles which create numerous centers able to produce very reactive radical species. Besides, the close contact between the CeO2 and rutile TiO2 provides easier charge transfer facilitating the formation of electron/hole pairs that is a necessary step in the overall photocatalytic process.

SYNTHESIS OF GRAPHENE/Mn0.2Cd0.8S HIERARCHICAL NANOSPHERES FOR PHOTOCATALYTIC DEGRADATION OF ORGANIC POLLUTANTS

The hierarchically structured hybrids of graphene and Mn0.2Cd0.8S solid-solution, resulting in G/Mn0.2Cd0.8S HN, are successfully synthesized by using microwave method with the assistance of L-Histidine. Moreover, X-ray diffraction (XRD), UV-vis absorption spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are employed to analyze the structural and optical properties. Furthermore, the decoloration of methyl orange (MO) under visible light irradiation indicates that the G/Mn0.2Cd0.8S HN is a promising photocatalyst for the degradation of organic pollutants. Herein, a possible photocatalytic mechanism of G/Mn0.2Cd0.8S is proposed, showing the synergistic influence of hierarchical nanospheres morphology, optimal bandgap and conductive graphene scaffold on photocatalytic activity. Overall, the photodegradation performance is improved due to the effective separation of electron/hole pairs and efficient transportation of photogenerated electrons from Mn0.2Cd0.8S to graphene. The current work demonstrates an environment-friendly route to fabricate multi-component chalcogenides for high-performance photocatalytic applications.

Fe-pillared montmorillonite as effective heterogeneous Fenton catalyst for the decolorization of methyl orange

The natural Na-type montmorillonite (Na-MMT) was pillared by iron polycation to obtain Fe-pillared montmorillonite (Fe-MMT). The materials were characterized by X-ray powder diffraction and N2 adsorption–desorption at low temperature. It was found that iron polycation was successfully inserted into MMT layers, and the textural properties of Fe-MMT could be adjusted by altering the amount of iron. Meanwhile, the decolorization of methyl orange (MO) by heterogeneous Fenton-like oxidation using Fe-MMT as catalyst was evaluated. The experimental results showed that Fe-MMT exhibited good decolorization performance of MO under 2.0 g L−1 of Fe-MMT-1.5, initial pH of solution 4, reaction time 90 min, and H2O2 concentration of 5 mmol L−1. Fe-MMT exhibited good stability for the decolorization of MO in solution for three successive runs. The decolorization process could be well described by pseudo firstorder kinetics model. Na-montmorillonite (MMT) pillared by iron polycation (Fe-MMT), an efficient Fenton-like catalyst was developed. The decolorization efficiency of methyl orange (MO) was dependent on the textural properties of Fe-MMT adjusted by altering the amount of iron. Excellent decolorization efficiency of MO (91.6–87.9%) was achieved under the optimal conditions.

Accelerated anaerobic biodecolorization of sulfonated azo dyes by magnetite nanoparticles as potential electron transfer mediators

Anaerobic decolorization of azo dyes has been evidenced to be an economical and effective pretreatment method, but its generally limited by the low decolorization efficiency, especially for biodecolorization sulfonated azo dyes. In this study, magnetite nanoparticles (MNPs) as a conductive material, was coupled into anaerobic system for enhancing decolorization of sulfonated azo dyes, i.e., methyl orange (MO), with technology feasibility and system stability emphasized. The results showed that the anaerobic decolorization capacity was significantly enhanced with addition of MNPs (at dose of 1 g/L), where the efficiencies of MO decolorization and aromatic amines formation were as high as 97.28 ± 0.78 % and 99.44 ± 0.25%, respectively. In addition, both electron transport system activity and sludge conductivity were also significantly improved, suggesting that a direct extracellular electron transfer had been successfully established via MNPs as RMs. Under continuous-flow experiments, addition of MNPs not only improved anaerobic system resistance environmental stress (e.g., high MO concentration, low hydraulic retention time and low co-substance concentration) but also accelerated sludge granulation. The relative abundance of functional species related to dissimilatory iron reduction and MO biodegradation were also enriched under MNPs stimulation. The observed long-term stable performance suggests the full-scale application potential of this coupled system for treatment of wastewater containing sulfonated azo dyes.