Degradation Of Azo Dye Research Articles

Constructed wetland-microbial fuel cell (CW-MFC) mediated bio-electrodegradation of azo dyes from textile wastewater.

Azo dyes constitute 60%-70% of commercially used dyes and are complex, carcinogenic, and mutagenic pollutants that negatively impact soil composition, water bodies, flora, and fauna. Conventional azo dye degradation techniques have drawbacks such as high production and maintenance costs, use of hazardous chemicals, membrane clogging, and sludge generation. Constructed wetland-microbial fuel cells (CW-MFCs) offer a promising sustainable approach for the bio-electrodegradation of azo dyes from textile wastewater. CW-MFCs harness the phytodegradation capabilities of wetland plants like Azolla, water hyacinth, and Ipomoea, along with microalgae such as Nostoc, Oscillatoria, Chlorella, and Anabaena, to break down azo dyes into aromatic amines. These intermediates are then reduced to CO2 and H2O by microalgae in the fuel cells while simultaneously generating electricity. CW-MFCs offer advantages including low cost, sustainability, and use of renewable energy. The valorization of the resulting algal and plant biomass further enhances the sustainability of this approach, as it can be used for biofuel production, nutraceuticals, pharmaceuticals, and bio-composting. Implementing CW-MFCs as a tertiary treatment step in textile industries aligns with the circular economy concept and contributes to achieving several sustainable development goals.

Ultrasonically Activated Liquid Metal Catalysts in Water for Enhanced Hydrogenation Efficiency.

Hydride (H-) species on oxides have been extensively studied over the past few decades because of their critical role in various catalytic processes. Their syntheses require high temperatures and the presence of hydrogen, which involves complex equipment, high energy costs, and strict safety protocols. Hydride species tend to decompose in the presence of atmospheric oxygen and water, which reduces their catalytic activities. These challenges highlight the need for further research to improve the stability and efficiency of catalytic processes and develop safer and cost-effective synthesis methods. This paper introduces an ultrasonic fabrication method for gallium hydride species on liquid metal (LM) nanoparticles (Ga-H@LM NPs) in water and describes the evaluation of their catalytic properties. The Ga-H@LM NPs were synthesized by dispersing liquid metals of eutectic gallium-indium in water using a two-step ultrasonication process in an ice bath. The presence of Ga-H species was confirmed by Fourier-transform infrared spectroscopy. The Ga-H@LM NPs demonstrated the rapid catalytic hydrogenation of 4-nitrophenol and reductive degradation of azo dyes within minutes without the need for external reducing agents like NaBH4. The proposed mechanism involves high-energy ultrasonic cavitation at the interface between LM NPs and water, which promotes the formation of H2 from water and its activation to form Ga-H on particles surface during ultrasonication. This study has significant implications for advancing the field of catalysis because it provides a novel and efficient catalytic method for the synthesis of stable hydride species on gallium oxides.

Demonstration of adapted packed-bed bioreactor for accurate and rapid estimation of biochemical oxygen demand: insights into the influence of microbial community structure and functions.

This study demonstrated a novel approach to accurately estimate 5-day biochemical oxygen demand (BOD5) in textile wastewater using a microbial consortium from food processing wastewater fixed on coconut fibers. Although glucose-glutamic acid (GGA) has been widely known as the most preferred substrates for microbial respiration, its calibration surprisingly resulted in an overestimation of BOD5 in textile wastewater due to its lower utilization rate compared to that of textile wastewater. After being adapted with a new nutrient environment composed of GGA and textile wastewater, the adapted packed-bed bioreactors (PBBRs) was capable of accurate estimation of BOD5 in textile wastewater using GGA standard solution. Metagenomic analysis revealed the dominance of the genera Enterobacter, Acinetobacter, Chryseobacterium, and Comamonas in the adapted microbial community, which are recognized for their significant potential in azo dye degradation. The imputed metagenome showed an enhanced showed an enhanced abundance of "Amino Acid Degradation" and "Carbohydrate Degradation" functions, confirming the improved ability of adapted community to utilization of GGA in the standard solution. These findings suggest that adaptation of exogenous microbial consortium to a nutrient environment composed of GGA and target wastewater may shift the community to that dominated by strains having both utilization ability of GGA and target compounds which, in turn, enhance the accuracy of the adapted PBBRs for estimation of BOD5 in target wastewater.

Biodegradation of azo dyes by Aspergillus flavus and its bioremediation potential using seed germination efficiency

The worldwide textile industry extensively uses azo dyes, which pose serious health and environmental risks. Effective cleanup is necessary but challenging. Developing bioremediation methods for textile effluents will improve color removal efficiency. The recent attention to effectively utilizing microbes to convert toxic industrial azo dyes into non-hazardous compounds has garnered significant attention. In the present study, four fungal strains—Aspergillus flavus, Aspergillus terreus, Aspergillus niger, and Fusarium oxysporium—were employed to screen for the degradation and detoxification of azo dyes including congo red, crystal violet, bromophenol blue, and malachite green. After eight days, A. flavus had degraded azo dyes at the maximum proportion. The maximum decolorization (%) was achieved at 50 mg/L of dye concentration, 8 days of incubation, pH 6, 30 °C temperature, sucrose as a carbon source, NaNO3 as a nitrogen source, Ca+2 as minerals, and using static culture. The efficient production of laccases, lignin peroxidase, and manganese peroxidase enzymes by A. flavus proved that the enzyme played a crucial role in decolorizing the harmful azo dyes. The Fourier Transform Infrared spectrometer (FT-IR) data validated the decolorization and degradation process brought on by absorption and biodegradation. Compared to control plants, the results of the phytotoxicity assay showed that the degraded product was less harmful to maize and common bean plant's growth and germination rates. As a result, the findings indicate that A. flavus is a viable option for remediating azo dyes. This aids in the biodegradation of azo dyes found in wastewater.

Effect of several amines on the morphology, structure, purity, and photocatalytic activity of Ni6MnO8 nanostructures

Water and wastewater contaminated by dyes are becoming a bigger global problem. The drawbacks of conventional treatment methods are their high prices, lack of sustainability, and partial elimination. Metal oxide semiconductor-based photocatalytic degradation has lately supplanted these techniques. One method promising for completely degrading azo dyes found in wastewater is photocatalysis. Ni6MnO8 nanostructures, a novel photocatalyst, were created in this study to aid in the photocatalytic breakdown of several dyes, especially Eriochrome Black T (EBT). These nanostructures were fabricated through a simple and low-cost co-precipitation method using different amines, including ammonia, tetraethylenepentamine, triethylenetetramine, and ethylenediamine (EDA) as precipitating and capping agents. The pure phase of Ni6MnO8 was achieved in the presence of ammonia. According to the DRS result (bandgap = 2.6 eV), visible light was used to conduct photocatalytic degradation tests on a several dyes solution. The results show that the degradation is greatly influenced by the type of catalyst, dye solution’s starting concentration, pH of dye solution, and the amount of catalyst used. Increased catalyst dose and acidic media result in increased degradation. The maximum degradation rate of Ni6MnO8 prepared in the presence of ammonia on EBT is 96.3% under visible light, and its pseudo-first-order reaction rate constant is 0.0182 min–1. The scavenger experiment revealed the hydroxyl radicals performed the superior role in the degradation of EBT. The recycling test indicated the high stability of Ni6MnO8, with the yield reduced by only 5.6% after five cycles.

Boosting Reactive Oxygen Species Generation via Contact-Electro-Catalysis with FeIII-Initiated Self-cycled Fenton System.

Contact Electro-Catalysis (CEC) using commercial dielectric materials in contact-separation cycles with water can trigger interfacial electron transfer and induce the generation of reactive oxygen species (ROS). However, the inherent hydrophobicity of commercial dielectric materials limits the effective reaction sites, and the generated ROS inevitably undergo self-combination to form hydrogen peroxide (H2O2). In typical CEC systems, H2O2 does not further decompose into ROS, leading to suboptimal reaction rates. Addressing the generation and activation of H2O2 is therefore crucial for advancing CEC. Here, we synthesized a catalyst by loading the dielectric material polytetrafluoroethylene (PTFE) onto ZSM-5 (PTFE/ZSM-5, PZ for short), achieving uniform dispersion of the catalyst in water for the first time. The introduction of an FeIII-initiated self-cycling Fenton system (SF-CEC), with the synergistic effects of O2 activation and FeIII-activated H2O2, further enhanced ROS generation. In the FeIII-initiated SF-CEC system, the synergistic effects of ROS and protonated azo dyes enabled nearly 99 % degradation of azo dyes within 10 minutes, a sixfold improvement compared to the CEC system. This represents the fastest degradation rate of methyl orange dye induced by ultrasound to date. Without extra oxidants, this system enabled stable dissolution of precious metals in weakly acidic solutions at room temperature, achieving 80 % gold dissolution within 2 hours, 2.5 times faster than similar CEC systems. This study also corrects the unfavorable perception of CEC applications under acidic conditions, providing new insights for the fields of dye degradation and precious metal recovery.

Synthesis of a three-phase heterojunction NdVO4/V2O5/BiVO4 by cation exchange method for the degradation of anionic azo dye orange II.

Photocatalytic degradation of the azo dye orange II using NdVO4/V2O5/BiVO4 under visible light is reported here, and this oxygen-rich defect three-phase heterojunction structure is constructed using a two-step cation exchange method. This heterojunction significantly enhances the separation and migration efficiency of photo-induced charges, while the accompanying oxygen defects effectively capture photogenerated electrons, thereby suppressing the recombination of electrons and holes. Experimental characterization and theoretical calculations demonstrate the efficient separation and transfer capabilities of photogenerated carriers and their excellent photocatalytic degradation performance. Particularly, when treating the anionic dye orange II, this heterojunction structure achieves a degradation efficiency of up to 96.15%. Cycling tests show that NVB-24 exhibits good stability during the reaction process. This research provides a promising photocatalyst for the efficient degradation of anionic azo dyes and offers new insights for developing high-quality photocatalytic materials.

Functionalized nanocatalytic PVDF membrane reactor for degradation of hazardous azo dyes

Functionalized nanocatalytic PVDF membrane reactor for degradation of hazardous azo dyes

Effective photocatalytic degradation and kinetic modelling of azo dyes by zinc oxide nanoparticles from Brevibacterium casei

Effective photocatalytic degradation and kinetic modelling of azo dyes by zinc oxide nanoparticles from Brevibacterium casei

Ultrafast degradation of azo dye using surface-activated Fe-based metallic glass

Ultrafast degradation of azo dye using surface-activated Fe-based metallic glass

Application of green silver nano-particles as anti-bacterial and photo-catalytic degradation of azo dye in wastewater

Ensuring everyone enjoys healthy lifestyles and well-being at all ages, Progress has been made in increasing access to clean water and sanitation facilities and reducing the spread of epidemics and diseases. The synthesis of nano-particles (NPs) by using microalgae is a new nanobiotechnology due to the use of the biomolecular (corona) of microalgae as a capping and reducing agent for NP creation. This investigation explores the capacity of a distinct indigenous microalgal strain to synthesize silver nano-particles (AgNPs), as well as its effectiveness against multi-drug resistant (MDR) bacteria and its ability to degrade Azo dye (Methyl Red) in wastewater. An extract of Spirulina platensis was obtained from a local source to synthesize silver nano-particles (AgNPs). The synthesized AgNPs were subsequently subjected to characterization utilizing several analytical methods, namely UV-visible spectroscopy, scanning electron microscopy (SEM), X-ray diffraction, and Fourier transform infrared spectroscopy (FTIR analysis). Subsequently, the disc diffusion method assessed their anti-bacterial efficacy against multi-drug resistant (MDR) bacteria and their ability to degrade Azo dye (Methyl Red) in wastewater. The nano-particles produced through biological synthesis exhibited a prominent peak in the UV-visible spectrum at a wavelength of 430 nm. Furthermore, these nano-particles were determined to possess a crystalline nature, with an average size of 28.72 nm and a distinctive star-like shape. The synthesized silver nano-particles (AgNPs) exhibited a dose-dependent anti-bacterial effect against some clinical bacterial isolates as multi-drug resistant (MDR), including Gram− ve bacteria such as Pseudomonas aeruginosa and Escherichia coli, as well as Gram+ ve bacteria like Staphylococcus aureus and Streptococcus pneumoniae. The action can be ascribed to the unique biological and physicochemical features of AgNPs, which facilitate the disruption of bacterial cell membranes. The UV-visible analysis solution after the introduction of AgNPs indicated that the decrease in the absorbance peak of methyl red was attributed to the existence of silver nano-particles. Metal nano-particles can be synthesized using environmentally friendly processes and hold great potential for combating multi-drug resistant bacteria and degrading Azo dyes. Silver nano-particles (AgNPs) are synthesized with an extract derived from the algae Spirulina platensis, which is a sustainable and eco-friendly alternative.

Degradation of Azo Dye by Dye-Degrading Bacteria

Synthetic aromatic compounds consisting of various functional groups are known as dyes. These colored compounds are often discharged in effluents, and they are very dangerous to aquatic life. The study was carried out to study potential azo dye-degrading bacteria. Bacteria were isolated from 9 soil and 7 effluent samples collected from different parts of Kathmandu Valley. Isolated bacteria were tested for dye tolerance and dye-tolerant bacteria were subjected to decolorization of three acid dyes: acid yellow 25, acid green 23 and acid orange 7. A change in optical density was observed to study the impact of inoculum concentration. All 19 isolated potential bacteria were identified by morphological and biochemical tests. Among these, 6 (60%) of Gram-positive and 4 (50%) of Gram-negative bacteria were dye tolerant. Three bacteria SO2-3W, SO3-4W and S16-4P were able to decolorize acid green 23. The impact of the increase in inoculum concentration was increased in decolorization percentage. SO2-3W, SO3-4W and S16-4P were identified as Bacillus spp. and Pseudomonas aeruginosa, respectively. The ability of Bacillus spp. and Pseudomonas spp. to tolerate and decolorize textile dyes at high concentrations encourages their use as a potential bioinoculant in the treatment of textile wastewater. Stam. J. Microbiol. 2024;14(1):1-4

Mechanism of decolorization and degradation of direct brown D3G by a halo-thermophilic consortium.

Azo dye wastewater has garnered significant attention from researchers because of its association with high-temperature, high-salt, and high-alkali conditions. In this study, consortium ZZ efficiently decolorized brown D3G under halophilic and thermophilic conditions. he results indicated that consortium ZZ, which was mainly dominated by Marinobacter, Bacillus, and Halomonas, was achieved decolorization rates ranging from 1 to 10% at temperatures between 40°C and 50°C, while maintaining a pH range of 7 to 10 for direct brown D3G degradation. Through the comprehensive utilization of UV-vis spectral analysis, Fourier transform infrared (FTIR), gas chromatography mass spectrometric (GC-MS) techniques, as well as metagenomic analysis, the decolorization and degradation pathway of direct brown by consortium ZZ was proposed. The azo dye reductase, lignin peroxidase, and laccase were also highly expressed in the decolorization process. Additionally, phytotoxicity tests using seeds of Cucumis sativus and Oryza sativa revealed that the intermediates generated showed no significant toxicity compared with distilled water. This investigation elucidated the pivotal contribution of consortium ZZ to azo dye degradation and provided novel theoretical insights along with practical guidance for azo dye treatment at halo-thermophilic conditions.

Enhanced photocatalytic degradation of azo dyes using hydrothermally synthesized vanadium pentoxide nanomaterials

<p style="margin-bottom:11px;text-align:justify;text-indent:36.0pt;"><span style="color:#002060;font-family:"Times New Roman",serif;font-size:12.0pt;line-height:107%;">This study employed a simple hydrothermal (HT) approach to synthesize vanadium pentoxide (V<sub>2</sub>O<sub>5</sub>) nanomaterials. The inherent limitations of V<sub>2</sub>O<sub>5</sub>, including low quantum efficiency and insufficient light sensitivity, restrict its potential for enhanced photocatalytic activity. The study investigates the photodegradation of methyl orange (MO) and Congo red (CR) dyes through annealing. X-ray diffraction (XRD) and Raman spectroscopy confirm the composition of V<sub>2</sub>O<sub>5</sub>, while SEM is used to observe the morphology of encapsulated nanoparticles. The bandgap of V<sub>2</sub>O<sub>5 </sub>is estimated to be between 2.51 and 2.73 eV using ultraviolet-visible (UV) spectroscopy. Additionally, the photodegradation of methylene blue (MB) dye is analyzed, with calcinated V2O5 achieving a 76% degradation efficiency of MB in 90 minutes. For CR and MO, degradation rates reached 97.91% and 86% within 200 minutes at a 20 mg/L dye concentration. The reaction rate constant for MB degradation was determined to be 8.19 x 10⁻⁵ s⁻¹. Overall, the HT-synthesized V<sub>2</sub>O<sub>5 </sub>exhibited enhanced photocatalytic activity due to its improved visible light absorbance, facilitating more effective photodegradation of azo dyes. </span></p>

Magnetic cobalt nanoparticles embedded in a carbonaceous hydrogel for the activation of peroxymonosulfate to degrade azo dyes and organic pollutants.

Heterogeneous cobalt-based catalysts have recently gained attention as persulfate activators to degrade dyes and organic pollutants in sulfate radical-based advanced oxidation processes (SR-AOPs). This study fabricated magnetic cobalt nanoparticles embedded in a carbonaceous hydrogel (Co@C) using high-temperature pyrolysis of the Co2+-embedded chitosan-graft-poly(acrylic acid) (Co2+-embedded CTS-g-PAA) hydrogel. Subsequently, the prepared Co@C was evaluated as a peroxymonosulfate (PMS) activator for degrading azo dyes. The catalyst showed the highest performance toward reactive red 141 (RR141) than Congo red, methyl orange, direct yellow 50, and reactive black 5. RR141 was completely degraded within 10min, with a 3.20min-1 pseudo-first-order rate constant. The degradation rate increased with higher catalyst dosage, PMS dosage, and temperature. The pH of the solution had a minimal effect on the degradation of RR141, indicating that the catalyst could be effective across a wide pH range. Moreover, the quenching experiment and the electron paramagnetic resonance analysis indicated that the catalytic system generated SO4•-, HO•, O2•-, and 1O2. The RR141 degradation was slightly affected by Cl-, NO3-, and SO42-. The catalyst demonstrated high efficiencies in real water samples. The catalyst could be easily recovered using a magnet and reused for ten cycles with only a 10% degradation efficiency loss. Furthermore, the catalyst could effectively degrade other organic pollutants, including tetracycline and 4-nitrophenol. This study demonstrates that the Co@C catalyst can effectively purify wastewater via SR-AOPs.

Creating and Analyzing Sb-TiO2 Photocatalysts for Effective UV-A Light Degradation of RR 120 and MO Dyes

Creating and Analyzing Sb-TiO2 Photocatalysts for Effective UV-A Light Degradation of RR 120 and MO Dyes

A Study on the Novel Use of Metal‐organic Frameworks (MOFs) as a Nanocomposite of MIL‐88A(Fe) for the Photocatalytic Degradation of Azo Dyes From Aqueous Solutions: Synthesis and Characterization

AbstractIn this research, a new metal‐organic framework (MOF) nanocomposite was synthesized using the hydrothermal method. The main objective is to create a photocatalytic nanocomposite based on Materials Institute Lavoisier (MIL) for degrading Direct Red 23 (DR23) and Direct Red 28 (DR28) dyes using visible LED light. This catalyst was reported as MIL‐88A(Fe). The study also examined the impact of various operating variables, such as initial dye concentration, catalyst dosage, and solution pH, on the performance of the synthesized materials. Results showed that pollutant degradation increased with higher catalyst dosages but decreased with increasing initial pollutant concentrations. One of the main objectives is to enhance the photocatalytic efficiency of MIL‐88A(Fe) for the degradation of azo dyes. This will simplify and optimize the synthesis conditions, as well as improve the understanding of the degradation mechanisms, stability evaluation, and reusability. The characteristics of the synthesized photocatalysts were analyzed using XRD, SEM, EDX, FT‐IR, and Raman techniques. XRD, SEM, and FT‐IR analyses confirmed the successful synthesis of the MIL‐88A(Fe) nanocomposite. The degradation of DR23 and DR28 dyes on the catalysts followed first‐order kinetics, supported by appropriate rate models. The data suggested that MIL‐88A(Fe) could effectively serve as a photocatalyst for pollutant degradation.

Kinetic study on the degradation of Acid Red 88 azo dye in a constructed wetland-microbial fuel cell inoculated with Shewanella oneidensis MR-1.

Removal of Acid Red 88 (AR88) as an azo dye from the synthetic type of wastewater was studied in a laboratory-made constructed wetland microbial fuel cell (CW-MFC) inoculated with Shewanella oneidensis MR-1 (SOMR-1). Plant cultivation was implemented using a typical CW plant known as Cyperus alternifolius. The complexity of the SOMR-1 cell membrane having different carriers of electrons and H+ ions gives the microbe special enzymatic ability to participate in the AR88 oxidation link to the O2 reduction. Nernst equation developed based on analyzing the involved redox potential values in these electron exchanges is describable quantitatively in terms of the spontaneity of the catalyzed reaction. Power density (PD) at 100mg/L of the AR88 under closed-circuit conditions in the presence of the plant was 11.83 mW/m2. Reduction of internal resistance positively affected the PD value. In determining degradation kinetics, two approaches were undertaken: chemically in terms of first- and second-order reactions and biochemically in terms of the mathematical equations for rate determination developed on the basis of substrate inhibitory concept. The first-order rate constant was 0.263h-1 without plant cultivation and 0.324h-1 with plant cultivation. The Haldane kinetic model revealed low ks and ki values indicating effective degradation of the AR88. Moreover, the importance of acclimatization in terms of the crucial role of lactate was discussed. These findings suggest that integrating the SOMR-1 electrochemical role with CW-MFC could be a promising approach for the efficient degradation of azo dyes in wastewater treatment.

Design of a New Catalyst, Manganese(III) Complex, for the Oxidative Degradation of Azo Dye Molecules in Water Using Hydrogen Peroxide.

In the current work, chloro(meso-tetrakis(phenyl)porphyrin) manganese(III) [Mn(TPP)Cl] was synthesized following two steps: the preparation of meso-tetraphenylporphyrin (H⁠2TPP) and the insertion of manganese into the free porphyrin H2TPP. The compounds were characterized using SEM, FT-IR, UV, TGA/DTA, and XRD analyses. Manganese(III) meso-porphyrins exhibited hyper-type electronic spectra with a half-vacant metal orbital with symmetry, such as [dπ:dxz and dyz]. The thermal behavior of [Mn(TPP)(Cl)] changed (three-step degradation process) compared to the initial H2TPP (one-step degradation process), confirming the insertion of manganese into the core of the free porphyrin H2TPP. Furthermore, [Mn(TPP)Cl] was used to degrade calmagite (an azo dye) using H2O2 as an oxidant. The effects of dye concentration, reaction time, H2O2 dose, and temperature were investigated. The azo dye solution was completely degraded in the presence of [Mn(TPP)(Cl)]/H2O2 at pH = 6, temperature = 20 °C, C0 = 30 mg/L, and H2O2 = 40 mL/L. The computed low activation energy (Ea = 10.55 Kj/mol) demonstrated the efficiency of the proposed catalytic system for the azo dye degradation. Overall, based on the synthesis process and the excellent catalytic results, the prepared [Mn(TPP)Cl] could be used as an effective catalyst for the treatment of calmagite-contaminated effluents.

Role of perovskite non-stoichiometry on catalytic oxygen dark activation for the removal of azo dyes from wastewater

Effluents of the dying and printing industries are a significant contributor to water pollution. Since synthetic dyes are primarily resistant to natural degradation, they remain in water bodies for an exceptionally long time if discharged untreated. Oxygen dark activation is a promising candidate for the degradation of azo dyes as it does not require the use of additional reagents or even the presence of light. It is an advanced catalytic oxidation process that converts oxygen dissolved in wastewater into reactive oxygen species, which subsequently break down dye molecules. The role of the catalyst is to accelerate the process by acting as a bridge for the electron transfer between the dye molecules and adsorbed oxygen. It has been reported that the textural and structural properties of the catalyst play a key role in generating reactive oxygen species. In this work, we synthesized, characterized, and evaluated a series of strontium-based perovskite oxides for the catalytic degradation of azo dyes under dark conditions. The degradation of different dyes was studied in a batch reactor under various conditions, and the reaction progress was monitored by UV-vis absorption spectroscopy. The results showed that the degradation of azo dye was faster when the azo bond was weakened by either electron-withdrawing groups or due to the formation of a stable hydrazone structure. To evaluate the effect of structural defects on the oxygen dark activation process, cation non-stoichiometry was separately introduced in the parent perovskite SrFeO3 at both A and B sites. Under identical reaction conditions, the degradation efficiency of A-site deficient perovskite Sr0.90FeO3 (94%) and B-site deficient SrFe0.80O3 (95%) was higher than the stoichiometric perovskite SrFeO3 (46%). These results demonstrate that cation deficiency in the SrFeO3 structure strongly favors the catalytic degradation of azo dyes via oxygen dark activation.