Degradation Of Azo Dye Research Articles

Sonochemical Facile Synthesis of Bismuth Oxide Nanoparticles Using Citrus Lemon Extract and Its Catalytic Activity on Azo Dye Degradation

The synthesis of bismuth oxide nanoparticles through sono-cavitation using citrus lemon extract as a simple, eco-friendly and cost-efficient method was evaluated. The aqueous extract of citrus lemon acted as a bio-reducing and capping/stabilizing agent in the single-step biosynthesis of bismuth oxide nanoparticles. Different instrumental techniques have been used to characterize the biosynthesized bismuth oxide nanoparticles, including UV–vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy (EDS). UV–vis spectroscopy revealed the formation of stable bismuth oxide nanoparticles at λmax of 400 nm with a surface plasmon resonance (SPR) band. TEM revealed that the biosynthesized bismuth oxide nanoparticles were rod shaped with a particle size of 26 nm. A potential mechanism for the formation of bismuth oxide nanoparticles with the influence of sono-cavitation has been suggested based on the observed findings. These catalytic capabilities of the bio-synthesized bismuth oxide nanoparticles were then evaluated by degradation of toxic azo dyes under different laboratory conditions. The azo dye Congo red (CR) was effectively degraded to 86% within 30 min under optimum experimental conditions using 0.12 g/mL catalyst. Thus, the phytochemical citrus lemon offers a cheap and eco-friendly solution for the synthesis of catalytic nanoparticles to degrade highly toxic organic compounds such as azo dyes.Graphical

Mechanistic investigation of azo dye removal from carbon-deficient dyeing wastewater using horizontal-vertical constructed wetlands

Azo dye degradation can be achieved by simulating a series of anaerobic and aerobic conditions within the constructed wetland (CW) system. The current investigation evaluated the effectiveness of a baffled horizontal-vertical CW system, planted with Typha angustifolia, simulating anaerobic-aerobic conditions to treat carbon-deficient synthetic dyeing wastewater containing 100 mg/L Reactive Yellow 145 (RY145) azo dye. In the absence of an available carbon source in dyeing wastewater, an optimum quantity of sodium acetate was supplemented as the substrate for microbial degradation of RY145. Influent dyeing wastewater characteristics were 5555 ADMI colour, 461 mg/L chemical oxygen demand (COD) and 39 mg/L total nitrogen (TN). During the operation period, the CW system achieved 97% colour, 87% COD, 95% ammonium nitrogen (NH4+-N) and 71% TN removals at 4 d hydraulic retention time (HRT). Favourable environmental conditions, such as low redox conditions and substrate availability in horizontal CW, contributed to a significant reduction in colour (96%). Most TN reduction (67%) happened in horizontal CW by denitrification and plant assimilation. The metagenomic study revealed that Proteobacteria, Bacteroidetes, Chloroflexi and Firmicutes were responsible for pollutant degradation within horizontal CW. The UV–visible spectra and high-resolution liquid chromatograph mass spectrometer (HR-LCMS) analysis confirmed that dye degradation intermediates generated from the breakage of azo bonds were eliminated in vertical CW with high redox conditions. The results of the phytotoxicity and fish toxicity experiments demonstrated a substantial toxicity reduction in the CW system-treated effluent.

Synergistic Ag/g-C3N4 H2O2 System for Photocatalytic Degradation of Azo Dyes.

Graphitic carbon nitride (g-C3N4), known for being nontoxic, highly stable, and environmentally friendly, is extensively used in photocatalytic degradation technologies. Silver nanoparticles effectively capture the photogenerated electrons in g-C3N4, enhancing the photocatalytic efficiency. This study primarily focused on synthesizing graphitic carbon nitride via thermal polymerization and depositing noble metal silver onto g-C3N4 through photoreduction. Methyl orange (MO) and methylene blue (MB) were targeted as the pollutants in the photocatalytic experiments under visible light in conjunction with a H2O2 system. The characteristics peaks, structure, and morphology were analyzed using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). g-C3N4 loaded with 6% Ag exhibited superior photocatalytic performance; the photocatalytic fraction of the degraded materials of the MO and MB solutions reached 100% within 70 and 80 min, respectively, upon adding 1 mL and 2 mL of H2O2. ·OH and ·O2- were the primary active free radicals in the dye degradation process within the synergistic system. Stability tests also demonstrated that the photocatalyst maintained good reusability under the synergistic system.

Cu@Zn@800 bimetallic-based carbon nanomaterials for dark-catalyzed degradation and 4-NP-catalyzed reduction of azo dyes

Metal-organic frameworks (MOFs) were adaptable templates that might be used to create multifunctional materials containing carbon nanostructures. In this work, we had prepared a novel Cu-MOF using fumaric acid (H2FA) and N,N′-bis(pyridin-3-yl)isophthalamide (3-bpia) as the mixed ligands. Then, the Cu-MOF was served as a template to derive bimetallic-based carbon nanomaterials by introducing a second metal through doped ZnO by both re-calcined and directly calcined methods (Cu@Zn@800) and single-metal-based carbon nanomaterials (Cu@800). Cu@Zn@800 was able to catalyze the degradation of azo dyes at a rate higher than 99.40 % because of its capacity to create h+ and ·OH active substances and the uniformity of its metal active sites. Additionally, Cu@Zn@800 might use NaBH4 to decrease 4-NP in 30 s with the rate of decline was over 100 %. Cu@Zn@800 was a special and efficient dual-functional material that might be used in a variety of ways to remove contaminants from water.

The Role of Ascorbic Acid in the Process of Azo Dye Degradation in Aqueous Solution.

In this work, the role of ascorbic acid in the process of azo dye degradation was explained. For this purpose, the kinetics of azo dye degradation under different conditions was studied. Among them, the influence of daylight protection/exposition, different concentrations of ascorbic acid (0.567-0.014 mol/dm3), and temperature (20 °C and 50 °C) on the rate of the dyes' degradation was considered. For this process, the kinetic equation was proposed, which indicates that the process of azo dye degradation using ascorbic acid is first order. Moreover, the observed rate constants were determined, and the mechanism of azo dye degradation was proposed. Spectrophotometry results, together with FTIR, fluorescence spectroscopy, and DFT calculations, explain the origin of the decolorization of the azo dyes and highlight the role of ascorbic acid in this process. Detailed analysis of the obtained products indicates that the process itself goes through several stages in which equally or more toxic compounds are formed. Obtained results from LCMS studies indicate that during tropaeolin OO degradation, 1,2-Diphenylhydrazine (m/z 185.1073) is formed. Thus, the process of azo dye degradation should be carried out in protective conditions. The proposed mechanism suggests that ascorbic acid at high content levels can be used for azo dye degradation from aqueous solution and can be an alternative method for their removal/neutralization from waste solution but with caution during the process.

Theoretical-experimental study of Fe–ZrO2 and Co–ZrO2. Oxidative degradation of methyl orange azo dye

In recent years, advanced oxidation processes (AOPs) based on the generation of sulfate radicals (SO4●-) (SR-AOPs) have emerged as an innovative method for the decontamination of water and wastewater. In this study, Fe(II) and Co(II) catalysts supported on ZrO₂ were synthesized and employed as an activator for PMS and PS for the degradation of methyl orange. The general objective is to gain detailed insight into the interaction between oxidants and supported metal catalysts at the molecular level. Experimental results and density functional theory (DFT) calculations were employed to analyze the potential activation mechanism of the oxidants. The support was prepared via coprecipitation, and metal ion deposition was achieved through incipient wetness impregnation. The characterization of the catalysts was conducted through atomic absorption spectrometry, X-ray diffraction and Fourier-transform infrared spectroscopy. The findings indicated that PMS was the most efficient oxidant, with Co–ZrO2 emerging as the most effective catalyst (77% MO mineralization), compared to Fe–ZrO2, which exhibited a lower degree of mineralization (37.6%) under the specified experimental conditions. The use of PS as an oxidant resulted in low levels of degradation for both catalysts. The remarkable catalytic efficacy of the Co–ZrO₂/PMS system was elucidated through the application of density functional theory (DFT) calculations. These revealed that the adsorption energy of the oxidants on Co–ZrO₂ is lower than that on Fe–ZrO₂, which could facilitate the subsequent release of radicals to the reaction medium.

Synthesis, characterization, and azo dye degradation performance of mechanically alloyed Mg65Cu20Y13La2 nanocrystalline powders

This research describes the synthesis of the multicomponent Mg65Cu20Y13La2 alloy by mechanical alloying (MA) to investigate the influence of milling times on the microstructure of alloy and degradation performance of methyl orange. The structural evolution of this alloy was investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectrometry (EDX) techniques. The thermal behavior of the alloys was investigated by differential scanning calorimetry (DSC). The crystallite size of the Mg65Cu20Y13La2 alloys was calculated using the Debye Scherrer equation with broadening of the XRD peaks. The methyl orange degradation efficiencies of the Mg65Cu20Y13La2 alloys were evaluated by using ultraviolet–visible (UV–Vis) spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), and gas chromatography–mass spectrometry (GC–MS) techniques. The XRD and SEM results showed that the microstructure of the powders changed during MA. After 10 h milling time, three intermetallic phases were obtained as Mg2Cu2La, Mg24Y5, and Mg2Cu. The results also showed that a solid solution phase, α-Mg(Cu, Y, La), with an average crystallite size 21 nm was formed after 100 h milling time. DSC trace of the Mg65Cu20Y13La2 powders showed two exothermic peaks for the 10 h milling time, while it did not show any peaks for the 100 h milling time. Photocatalytic decomposition of the methyl orange solution by the Mg65Cu20Y13La2 alloy was evaluated by UV–Vis spectra with a decrease in absorbance at a wavelength of 465 nm. After a 20 min exposure, UV–Vis, FT-IR, and GC–MS analysis showed that the methyl orange samples were almost completely degradation by using the Mg65Cu20Y13La2 powders. The Mg65Cu20Y13La2 alloy exhibits a good reusability of 92% by the four cycle and a high efficiency was achieved in all the pH values in the range of 5–9. The results prove that the Mg65Cu20Y13La2 alloy is an efficient and promising material for dyeing wastewater treatment.

Decolorization and detoxification of direct blue 5B by a Marinobacter-dominated halo-thermoalkalophilic consortium

Azo dye-containing sewage is commonly detected at high salinity, temperature and pH. In this study, a halo-thermoalkalophilic azo dye decolorization consortium was enriched and named “consortium HL”. Consortium HL which was dominated by Marinobacter (84.30%), Desulfocurvibacter (1.89%), and Pseudomonas (1.85%), was able to completely decolorize Direct Blue 5B (DB5) during incubation with the material at 5% salinity, 50 °C, and pH 9 for 30 h. The decolorization mechanism was proposed based on combined metagenomic analysis, GC‒MS, and enzymatic activity detection. The action of the consortium HL showed great tolerance to variations in salinity, temperature and pH. A phytotoxicity study indicated that the metabolic intermediates showed no significant toxicity to the generation of Cucumis sativus and Oryza sativa seeds. This study, in which azo dye decolorization and degradation under high-salt, high-temperature and high-alkalinity conditions were investigated and deeply analyzed by metagenomic information, is the first report regarding the ability of Marinobacter to decolorize azo dyes at high temperatures.

Ultrasound-Assisted Photocatalytic Degradation of Azo Dyes under Visible Light Irradiation Using Polythiophene-Decorated CoFe2O4 Nanohybrids

The present work reports the synthesis of cobalt ferrite and its nanohybrids with polythiophene (PTh) in the weight ratios of 10% and 20%. The ferrite and its nanohybrids were characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy coupled with elemental mapping (Fe-SEM) to confirm the morphology as well as the structure of the synthesized nanohybrids. The nanohybrids were tested for their photocatalytic activity upon modification of PTh against Alizarin Yellow (AY), Congo Red (CR) and Brilliant Blue (BB). Almost 100% degradation was achieved in 30 min using 50 mg of the photocatalyst. The effect of catalyst concentration and dye concentration was also investigated to explore optimum concentration of the photocatalyst required for rapid degradation of the dye. The generation of radicals responsible for degradation was analyzed by radical scavenging experiments and a probable mechanism of degradation was proposed.

Sustainable degradation of azo dyes using Foeniculum vulgare seed extract-derived zinc oxide nanoparticles

Sustainable degradation of azo dyes using Foeniculum vulgare seed extract-derived zinc oxide nanoparticles

Green synthesis of silver nanoparticles from waste leaves of tea (Camellia sinensis) and their catalytic potential for degradation of azo dyes

Tea leaves are discarded after use as waste material. An attempt was made to explore the potential of tea waste as an alternative source of extensive reducing agent for green and biocompatible synthesis of silver nanoparticles (WT-AgNPs) from silver nitrate salt, and prospective utilization for degradation of toxic azo dyes such as methyl orange and Congo red occurring in effluents. Green tea extract was also used as reducing agent to synthesize AgNPs (GT-AgNPs) to compare their physicochemical properties and efficiency vis-à-vis WT-AgNPs. Both WT-AgNPs and GT-AgNPs were characterized by Ultraviolet-Visible (UV) and Fourier Transform Infrared (FTIR) Spectroscopy, particles size and zeta potential measured by Dynamic Light Scattering (DLS), surface morphology and elemental composition determined by Field Emission Scanning Electron Microscopy (FESEM). The average particle size, zeta potential and surface plasmon resonance (SPR) were 74.85 nm, -22.62 mV, 422 nm and 69.53 nm, -21.28 mV, 420 nm for WT-AgNPs and GT-AgNPs, respectively. Catalytic degradation reaction of methyl orange and Congo red using the biogenic AgNPs followed the pseudo-first order kinetics in both cases. The rate constants of methyl orange dye (100 ppm) degradation using the catalysts (WT-AgNPs and GT-AgNPs) were 0.087 s−1(R2=0.922) and 0.099 s−1 (R2=0.963) respectively, showing 93 % and 95.5 % degradation of dye in 40 min in presence of NaBH4. For Congo red (100 ppm) degradation, the rate constants were 0.112 s−1 (R2=0.917) and 0.113 s−1(R2=0.943). Both WT-AgNPs and GT-AgNPs exhibited bacteriostatic effect inhibiting growth of E. coli. The study offers potential use of waste tea leaves as an effective reducing agent for large-scale green synthesis of silver nanoparticles having multifarious environmental applications in general, dye degradation and antibacterial action in particular.

Adroit effect of copper nanoparticles and copper nanozyme and their effective decolorization of azo dyes

Copper nanoparticles (CuNPs) have garnered considerable attention owed to their straightforward and cost-effective synthesis techniques, making them suitable for various applications across several fields. This paper describes a straightforward method for synthesizing CuNPs using the aqueous chemical reduction approach. A unique copper nanozyme (CNZ) is also prepared to degrade dyes. The nanoparticles were analyzed using various techniques to examine their morphological structure, optical properties, functional groups, and crystallite size via SEM, UV–visible spectrophotometry, FTIR, XRD, and zeta potential with particle size analyzer. SEM analysis showed that the CuNPs have a cubical form, with particle size fluctuating from 250 to 300 nm. The CNZ has a flower-like structure with a typical 100 to 150 nm size. The zeta potential of CuNPs is measured to be + 23.4 mV, indicating a high level of stability for the nanoparticles. The XRD evaluation showed that the CuNPs displayed a prominent peak at an angle of 36.64°, indicating a crystallite size of 26.97 nm. The CNZ displayed a peak at 31.18 nm, corresponding to a crystallite size of 44.84 nm. The capacity of CuNPs and CNZ to degrade a combination of dyes (Methyl orange, Methyl red, Congo red, Tropaeolin-O, and Tartrazine) was investigated. The innovative approach utilizing CNZ and CuNPs resulted in a degradation percentage of 84.61 % for mixed colors. Experimental findings have demonstrated that the combined effect of CuNPs and CNZ is remarkably effective in catalytically degrading azo dyes, making it a highly efficient method for treating effluents from the textile sector and wastewater treatment.

Photocatalytic Degradation of Azo Dyes in Aqueous Solution Using TiO2 Doped with rGO/CdS under UV Irradiation

Photocatalytic Degradation of Azo Dyes in Aqueous Solution Using TiO2 Doped with rGO/CdS under UV Irradiation

Effective degradation of azo dyes by ABTS (2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) mediated laccase. Kinetic studies

Laccases are enzymes with low substrate specificity that in certain cases require the presence of a mediator in order to work properly. Therefore, this paper investigated the degradation of Orange G, Ponceau 4 R and Methyl Red in the presence of laccase isolated from Trametes versicolor and laccase-ABTS system. Laccase, in high concentration, was able to oxidize only Orange G and Ponceau 4 R, with a degree of decolorization less than 10 % in 20 min. In the presence of laccase-ABTS system, the reaction is much faster, and at least 40 % of dyes were degraded in 15 min. A kinetic model accounting for enzymatic oxidation of all dyes, including a step for enzyme operational inactivation, was proposed. This study proves that we can use a single kinetic model for the oxidation of all dyes in the laccase-ABTS system.

A Zn-Ca-Based Metallic Glass Composite Material for Rapid Degradation of Azo Dyes.

The catalytic capabilities of metals in degrading azo dyes have garnered extensive interest; however, selecting highly efficient metals remains a significant challenge. We have developed a Zn-Ca-based metallic glass composite which shows outstanding degradation efficiency for Direct Blue 6. This alloy comprises a Zn2Ca crystalline phase and an amorphous matrix, allowing for the degradation of azo dyes within minutes in a wide temperature range of 0-60 °C. Kinetic calculations reveal an exceptionally low activation energy of 8.99 kJ/mol. The rapid degradation is attributed to the active element Ca and the unique amorphous structure of the matrix, which not only facilitates abundant redox conditions but also minimizes the hydrolysis of the active element. The newly developed metallic glass composite exhibits a notably higher azo dye degradation rate compared to those of general metallic glasses, offering a new avenue for the rapid degradation of azo dyes. This paper holds significant importance for the development of novel azo dye wastewater treatment agents.

In-situ synthesis of SnO/CuSnO3 nanostructures to catalyze azo dye degradation, CO2 reduction, and amines direct alkylation reactions under visible light

The extensive use of photocatalysis to address environmental concerns, energy production, and organic transformations has attracted attention in recent decades. The SnO/CSO photocatalytic materials were fabricated through a single-step hydrothermal method and comprehensively characterized using a muti-technique approach to demonstrate the physicochemical, morphological, and electronic features. According to the photocatalytic experiments, the SnO/CSO could remove >96 % of acid blue 92 (AB92) azo dye under optimum conditions, with rate constant 2.37 × 10−2 min−1. Furthermore, the photocatalyst significantly outperformed commercial TiO2 (P25), in reducing CO2 to CO and CH4 with a production rate of 10.8 and 1.18 μmol g−1 h−1, respectively, under visible light irradiation. The successful direct alkylation of amines to valuable organic compounds within 10 min of the reaction time with a conversion selectivity of >90 % was another capability of the materials, making it a good candidate for pharmaceutical synthesis purposes.

Green synthesized AgNPs entrapped in polymer hydrogels for azo dye degradation

Green synthesized AgNPs entrapped in polymer hydrogels for azo dye degradation

Potential of Marine Macroalgae in Stabilizing Bio-Fabricated Nanoparticles for Photodegradation Application: A Review

Marine macroalgae, or seaweeds, have emerged as promising sources for the green synthesis and stabilization of nanoparticles, offering remarkable potential in photodegradation processes. These abundant and renewable resources harbor a diverse array of bioactive compounds, including polysaccharides, proteins, flavonoid, and pigments, which can act as reducing, capping, and stabilizing agents. The integration of macroalgae-derived stabilizing agents into nanoparticle synthesis confers unique properties, enhancing photocatalytic performance and stability. This review comprehensively examines the role of marine macroalgae as stabilizing agents for bio-fabricated nanoparticles in photodegradation applications in particular for toxic azo dye degradation and organic compounds. It explores into the mechanisms of nanoparticle synthesis and stabilization, explores the diverse macroalgal species employed, and evaluates their photocatalytic efficiency against various organic and inorganic pollutants in wastewater. Furthermore, the review critically analyzes the challenges and future perspectives in this field, offering insights into the development of green, sustainable, and efficient remediation strategies for environmental contaminants.

Pyrolytic conversion of nylon-6 and red mud into N-doped carbon composite and its application into azo-dye degradation

The continuous growth of the global population and industries has led to the mass generation of plastic and industrial waste, posing significant environmental challenges due to their incompatibility with conventional waste management practices. This study investigates the thermochemical conversion of plastic (nylon-6) and industrial waste (red mud) into value-added products, presenting a waste-to-resource conversion strategy. Nylon-6 and red mud were co-pyrolyzed, resulting in a metal-carbon composite characterized as porous N-doped graphitic carbon with embedded Fe0 particles. Application of the composite to an amaranth solution demonstrated its ability to activate persulfate, facilitating amaranth oxidation at a rate (kobs = 1.78 min−1) significantly higher than other Fe-based catalysts. Quenching experiments verified the generation of OH· and SO4·- radicals during activation, with the latter playing a dominant role in amaranth degradation. The composite exhibited robust reusability, maintaining an amaranth removal efficiency of >80 % after five reaction cycles. Additionally, red mud significantly enhanced syngas (H2 and CO) generation from nylon-6, suggesting a catalytic effect. In conclusion, the proposed thermochemical approach offers a viable method for converting waste materials into valuable products, including environmental catalysts and gas fuels.

Improving azo dyes degradation by CoFe2O4-activated peroxymonosulfate: Performance, degradation mechanism, and ecotoxicity assessment

Development of an effective catalyst is essential to eliminate the risks to ecological environment and human health caused by the accumulation of azo dyes in environmental water. Herein, the cobalt ferrite (CoFe2O4) nanoparticles (NPs), facilely prepared by a one-pot hydrothermal procedure, were developed for peroxymonosulfate (PMS) activation towards Congo red (CR) degradations. The key experimental parameters were comprehensively investigated to optimize the degradation performance for CR in CoFe2O4/PMS system. Under optimal conditions, the CoFe2O4 NPs exhibited an excellent capability for PMS activation to degrade CR with the degradation efficiency of nearly 100 % in a wide range of pH values (3.0–9.0). The electron paramagnetic resonance (EPR) and quenching experiments confirmed that the entire CR degradation process was dominantly by the non-radical (1O2) and surface-bound SO4·−and ·OH. CoFe2O4 NPs displayed the remarkable stability and reusability, with degradation efficiency of 85.5 % even after six recycles. The possible degradation pathway in CR degradation process was proposed, and the qualitative analysis and ecotoxicity of the degradation intermediates were investigated. This work provided a facile and green strategy to prepare a prospective catalyst for the efficient removal of azo dyes by PMS activation.