Methylene Blue Degradation Research Articles

H2O2-sensitized titania with activity under visible light and in the dark

The development of visible-light photoactive materials decomposing pollutants and removing bacteria is a frequent motivation for scientific research. However, the reliance on light to sustain the degradation process restricts the practical application of photocatalysts. In this paper, titania was sensitized with H2O2 to overcome this problemand exhibit photocatalytic and dark activity. Efficiency of degradation of standard pollutant (methylene blue) and antibacterial properties (tested on two strains of bacteria: Enterococcus faecalis and Escherichia coli) were asessed. The comprehensive effect of this material is a result of the peroxide-assisted sol-gel method, without heat treatment, which allows obtaining titanium dioxide with hydroxy and adoxygen groups on the surface and in the volume. The presence of the peroxo and superoxo groups was confirmed using Raman, IR and EPR spectroscopies. The thermal stability of the adoxygen groups was analysed by TG/DSC analysis. X-ray diffraction indicated the formation of an amorphous layered structure. The Tauc plot revealed midgap states which reduced the band gaps towards visible light. The H2O2-sensitized TiO2 was characterized by negative surface potential (pHPZC=3.2) which improved adsorption.The study provides insight for the development of self-cleaning and antibacterial surfaces.

Effect of crystallite size reduction and widening of optical phonon vibration due to AC variation on ZnO/Mg composites in implementation of methylene blue degradation.

The fashion industry's reliance on dyes contributes significantly to environmental pollution, which disturbs the ecological balance. To address this issue, we used ZnO/Mg combined with activated carbon (AC) at various concentrations (0.1g, 0.5g, and 1g), which were synthesized via sol-gel and mechanical alloying processes. The analysis of X-ray diffraction shows reduced crystallite size, with d-spacing change ( d ) for ZnO/Mg/AC (0.5g) and ( d ) for ZnO/Mg/AC (1g), respectively. The results of the IR spectrum indicated the main vibrations is MgO and Zn-O bonds at wave numbers 673cm-1 and 467cm-1. It was found that ZnO/Mg/AC (1g) shows high degradation performance : 86.15% as a consequence of reduced crystallite size: 22.67nm, decreased skin depth: 0.002cm, widening of optical phonon vibration ( ): 252cm-1 and increased : 4.6eV as a function AC variation. Moreover, the finding of high photocatalytic performance 80% for 0.25mLMB dissolved in 250mL distilled water is obtained from all composites. Based on these results, ZnO/Mg/AC shows potential as a photocatalyst to solve the MB waste problem.

Photocatalytic mechanism of BaTi5O11 nanocrystals for methylene blue degradation

The electron-band structure of BaTi5O11 nanocrystals was calculated to explore their photocatalytic mechanism. The BaTi5O11 nanocrystals synthesized by a hydrothermal method had a direct band-gap of 3.51 eV, and 82 % methylene blue (MB) was photodegraded after 30 min UV-light irradiation. They showed good photocatalytic performance due to distorted TiO6 octahedra in the crystal structure and nano-size grains of BaTi5O11. The photogenerated carriers were formed by excitation of Ti-O bond which broke under UV-light irradiation, then migrated to the surface of BaTi5O11 nanocrystal. The adsorbed hydroxy groups on the surface were oxidized by photogenerated holes to form •OH radicals, and the photogenerated electrons could be captured by the adsorbed O2 to form •O2− radicals. Both •OH and •O2− radicals played the important role for MB photodegradation.

Photocatalysis and microwave absorption performance of cobalt particles dispersed on activated carbon surface under the role of surface, optical, and magnetic properties

Ensuring the availability of clean water and solve electromagnetic interference are a fundamental action to support a better life. Here, the bifunctional material as photocatalyst and absorber microwave were prepared from activated carbon composite with Cobalt (AC-Co (0, 10, & 20)%) by stirring-assisted impregnation method as an easy and environmentally friendly procedure. The effectiveness of the material as a catalyst is observed from its surface condition as an active site, and we also consider the electrical and magnetic properties as aspects of the role in photodegradation capability. It was found that AC-Co (10) showed a methylene blue and pesticide degradation capability of >90 % for an adsorbent mass of 1.5 g within 5 days treated without artificial irradiation and stirring to imitate the environmental conditions. The microwave absorption capability by the composite shows a maximum absorption of −19.1 dB at 10.12 GHz for AC-Co (0), while the presence of Co manages to provide a higher working frequency shift but reduced absorption performance. These reported performances are supported by the appropriate distribution of Co particles scattered on the AC surface, larger μ'', and higher consistency of Δ(LO−TO) positions.

Rational Engineering of Nanostructured NiS/GO/PVA for Efficient Photocatalytic Degradation of Organic Pollutants

A novel nanocomposite film synthesized from an inexpensive and easily accessible polymer such as poly (vinyl alcohol) (PVA), which is coated with nickel sulfide (NiS) and graphene oxide (GO), was obtained from used drinking-water bottles. The produced coated film was examined as a potential photocatalyst film for wastewater treatment promotion in a batch system for the removal of methylene blue (MB) and tetracycline (TC) antibiotics. The experimental results show that the presence of GO significantly increases the photocatalytic efficiency of NiS, and the MB and TC degradation results proved that the incorporation of GO with NiS led to a more than one-and-a-half-fold increase in the removal percentage in comparison with the NiS/PVA-coated film. After 30 min of illumination using GO/NiS/PVA-coated film, the removal efficiency reached 86% for MB and 64% for TC. The photodegradation kinetic rate followed the pseudo-first-order rate. Furthermore, the response surface methodology (RSM) model was utilized to study and optimize several operating parameters. The ideal circumstances to achieve 91% elimination of MB are 12 mg L−1 MB initial concentration, two lamps, and an illumination time of 15 min; however, to achieve 85% TC removal, 11 mg L−1 TC initial concentration, two lamps, and a 45 min illumination time should be used. The fabricated nanocomposite photocatalyst film seems to have promise for use in water purification systems.

Effective removal of textile dye via synergy of adsorption and photocatalysis over ZnS nanoparticles: Synthesis, modeling, and mechanism

In this work, we prepared sulfur-zinc nanoparticles (ZnS-TGA) functionalized with thioglycolic acid by a hydrothermal method and tested their photodegradation ability by solar irradiation. ZnS-TGA were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), high-resolution transmission electron microscope (HR-TEM), UV–Vis spectrophotometer and photoluminescence spectroscopy. In the characterization of these nanoparticles, thioglycolic acid proved to be a strong capping ligand, with a specific surface area of 36.82 m2/g and an average size of 7.15 nm. To test the photocatalytic degradability of the product, methylene blue (MB) was used as a model pollutant. Various operational variables were investigated, including pH, amount of nanoparticles, dye concentration, contact time and temperature. The equilibrium adsorption tests, and the statistical physical calculations allowed the analysis of the energetic and steric variables of the adsorption of MB dye molecules on the surface of these nanoparticles. The equilibrium data were well fitted with Langmuir-Freundlich (L-F) and the adsorption kinetics with pseudo-first order. The maximum adsorption capacity of the MB dye removal process was 30.92 mg g−1 at pH 7 and 298 K, and this process was spontaneous and exothermic. The dye molecules and the surface of the nanoparticles exhibited physical interactions with adsorption energies of 23.31–25.92 kJ/mol. The photocatalytic activity of these nanoparticles resulted in a dye degradation efficiency of 91.1 % in 180 min. The photocatalytic efficiency remained almost unchanged after five consecutive degradation cycles, resulting in a methylene blue degradation of 85 %. According to these results, these environmentally friendly nanoparticles have the potential to purify industrial and urban liquids contaminated with harmful organic compounds such as dye molecules.

Pectin functionalized with Cu/Fe nanoparticles for enhanced degradation of methylene blue from wastewater

IntroductionIn the present study, citrus pectin-stabilized copper/iron bimetallic nanoparticle (NP) catalyst has been used for the degradation of methylene blue (MB) dye in wastewater produced from the food industry.MethodsThe P@Cu/Fe composites were synthesized by co-precipitation and the sol–gel methods.Results and discussionThe characterization of the composites was carried out using UV, FTIR, SEM, and XRD techniques, revealing that P1@Cu/FeNPs synthesized through co-precipitation had a particle size of 150–35 nm with an irregular spherical and hexagonal shape. P2@Cu/FeNPs, synthesized using the gel combustion method using triethylamine as fuel, proved to be a better nanocatalyst with spherical particles having a uniform structure and size distribution of 105–23 nm. The mean zeta potential value of P1@Cu/FeNPs was found to be between 0 and 5mv, showing the composite to be less stable and 13 mv for more stable P2@Cu/FeNPs. The degradation of MB by P1@Cu/FeNPs was recorded up to 23.57% after 35 min and the nanocomposite synthesized by the sol–gel method exhibited 97.28% degradation in 30 min. The P2@Cu/FeNPs performed the best degradation due to their synergistic impact. In essence, this research represents a step toward the synthesis of bimetallic NPs using a biomaterial (citrus pectin) with improved synergistic photocatalytic potential that can induce different features in nanomaterials. Pectin-functionalized NPs using different metals should be synthesized and tested for different catalytic applications.

Lignin-Derived Sustainable Nano-Platforms: A Multifunctional Solution for an Efficient Dye Removal.

In contrast to conventional non-biobased adsorbents, lignin emerges as a cost-effective and environmentally benign alternative for water treatment. This study identifies unexpected and unpredicted multifunctional properties of lignin nanoparticles (LNPs). LNPs, which are prepared by simple physical processes, demonstrated for the first time to behave as multifunctional materials able to adsorb and photodegrade methylene blue (MB) in aqueous medium upon UV irradiation. Furthermore, the synthetic approach adopted to synthesize LNPs - and therefore their surface properties - strongly affects their performances. More specifically, LNPs obtained by solvent-antisolvent nanoprecipitation (SLNPs) show the highest MB adsorption properties (98 % removal), reaching a maximum adsorption capacity of 43.0 mg g-1, and the fastest adsorption kinetics with respect to other lignin-based adsorbents. Conversely, hydrotropic LNPs (HLNPs) exhibit exceptional photocatalytic activity, resulting in 98 % MB degradation over 6 hours of UV irradiation, combined with the ability to be easily recycled and reused. The present effort paves the way for the use of LNPs as efficient multifunctional materials able to perform concurrently adsorption and photocatalytic degradation of dye pollutants, toward the creation of a sustainable biobased water treatment platform.

A novel hydrothermal approach to preparing ZnO flower-like using CQDs as growth seeds

This study presents a new synthesis route to prepare ZnO flower-like particles. Firstly, carbon quantum dots (CQDs) were prepared hydrothermally, using the Malva sylvestris flower as the sole carbon source. Subsequently, flower-like particles of ZnO/CQDs were synthesized using CQDs seeds and the same hydrothermal process. The efficiency of the redox process of solar excitation was measured by reducing the dye methylene blue (MB). The SEM and TEM characterization shows ZnO flower-like particles of around 1.5 µm whose petals are formed by crystallites of around 10 nm. ZnO nanocrystals appear embedded in an amorphous carbon matrix. TEM images show carbon quantum dots on the surface of ZnO flowers. Without using Malva sylvestris, ZnO morphologies are not formed; instead, 2D nanolaminates appear. The ZnO/CQDs nanocomposite achieved 98 % MB degradation in 80 min. The small size of CQDs can be a good scenario for the growth of crystalline nanostructures using the nanocarbon seed.

Artificial Neural Network-driven Optimization of Fe3O4 Nanoparticles/PVDF Macrospheres in Fenton-like System for Methylene Blue Degradation

Efficient degradation of industrial dyes remains a critical challenge in environmental engineering. This study introduces a novel Fe3O4 nanoparticles/PVDF macrospheres in a Fenton-like system, optimized using an Artificial Neural Network (ANN) for the degradation of Methylene Blue (MB). A feedforward backpropagation neural network model to optimize and predict the performance of this advanced oxidation process under various operational conditions. The model was trained, validated, and tested with robust datasets, demonstrating high predictive accuracy and generalization capability. The Mean Square Error (MSE) and Root Mean Square Error (RMSE) during testing were 0.0200 and 0.1414, respectively, indicating precise predictions. The coefficient of determination (R²) and correlation coefficient (R) were exceptionally high at 0.9744 and 0.9871, affirming the model's ability to capture the underlying dynamics of the degradation process effectively. The ANN-driven approach not only enhanced the efficiency of the MB degradation process but also provided significant insights into the scalability and applicability of the Fe3O4/PVDF system for practical water treatment solutions. This study underscores the potential of integrating advanced machine learning techniques with chemical engineering processes to achieve sustainable and efficient environmental management solutions, particularly for the treatment of recalcitrant wastewater contaminants.

Green Synthesis of Silver Nanoparticle Using Parmotrema parmutatum Extract and its Application in Colorimetric Sensing and Photolytic Degradation of Organic Dye

Background: Silver nanoparticles possess distinctive characteristics, including chemical stability, high thermal and electrical conductivity, and linear optical properties, making them unique and fascinating. The rise of green synthesis methods for silver nanoparticles is garnering significant interest among researchers, surpassing traditional chemical and physical approaches due to the environmentally friendly, cost-effective, and convenient nature of synthesis. This approach stands as a viable alternative across various sectors, encompassing research, industry, and environmental safety initiatives. Method: Parmotrema permutatum was utilized in the synthesis of silver nanoparticles, followed by their characterization using ultraviolet-visible spectroscopy, Fourier-transformed infrared spectroscopy, X-ray diffraction, energy dispersive X-ray analysis, and scanning electron microscopy. These nanoparticles are subsequiently employed for detecting methylene blue, formaldehyde, and hazardous mercury metal ions as well as photocatalytically degrading methylene blue. objective: Green Synthesis of Silver Nanoparticle Using Parmotrema parmutatum Extract and Its Application in Colorimetric Sensing Results: The silver nanoparticle synthesized was confirmed by a color change and the maximum peak of the SPR band was at 420 nm in the UV spectrum. The crystal has face-centered cubic (FCC) structure with an average size of 12.78 nm. The lichen extract contains polyphenolic groups which act as capping agents. synthesized silver nanoparticles were used to detect formaldehyde and hazardous Hg2+ ions separately. A color change was observed. The detection limit of Hg2+ was 600 μL. Likewise, silver nanoparticles were used to degrade methylene blue. The blue color of methylene blue disappeared. The efficiency of silver nanoparticles was found to be 72% in 4 hours and 87.82% in 24 hours. Conclusion: Parmotrema permutatum has the potential to reduce Ag2+ to Ago and acts as a capping and stabilizing agent, it can be used to biosynthesize silver nanoparticles and can detect formaldehyde, and Hg2+ ions, in addition, it also degrades methylene blue photolytically.

Synthesis and characterization of a novel GaN – Poly (3,4-ethylene dioxythiophene)-Poly(thiophene) Hybrid Nanocomposite: Dual functionality as an electrocatalyst for OFZ and photocatalyst for methylene blue degradation

We introduce GaN-PEDOT-PTh, a groundbreaking hybrid nanomaterial synthesized via a two-step process involving ammonolysis and chemical oxidative techniques. The successful formation of core–shell structures underscores the adaptability of the GaN-PEDOT-PTh approach, particularly in enhancing photocatalytic performance. These characteristics significantly elevate its catalytic efficiency, as notably demonstrated by the rapid degradation of methyl blue (MB). Impressively, the hybrid achieves a 95.77 % MB degradation rate within just 80 min, attributed to its effective suppression of rapid electron-hole recombination, thereby amplifying overall photocatalytic activity. Furthermore, we utilized differential pulse voltammetry to detect the OFZ (OFZ) drug, employing a GaN-PEDOT-PTh-modified GCE as the working electrode. Linear responses to OFZ within the concentration range of 0.3 × 10−7 to 4.1 × 10−8 M were observed, demonstrating sensitivities with detection limits (DL) and quantification limits (QL) of 23.52 × 10−8 M µA−1 and 78.33 × 10−8 M µA−1, respectively.

Morphological effect of TiO2 nanoparticles in TiO2/g-C3N4 heterojunctions on photocatalytic dye degradation

Abstract The effects of TiO2 nanoparticle (NP) morphology on the photocatalytic activity of physically assembled TiO2 NP/g-C3N4 heterojunctions (TCNPHY) were investigated. Spherical, spindle, and cubic TiO2 NPs were synthesized and separately supported on g-C3N4 nanosheets to form physically assembled TCNPHY catalysts. The photocatalytic activity for methylene blue degradation observed for TCNPHY with the cubic TiO2 NPs supported higher light absorption and a lower recombination rate; therefore, this was an adequate catalyst for the construction of catalytically active heterojunctions. The cubic TiO2 TCNPHY exhibited a degradation rate that was 2.2 times higher than that for the g-C3N4 nanosheets alone.

Vacancy-strengthened Cu/Co composite oxides for efficient removal of methylene blue via peroxymonosulfate activation: Synergism of multiple Lewis acid sites

The development of suitable catalysts poses a challenge for the peroxymonosulfate (PMS) activation system used in decontamination process. Here we constructed a series of vacancy-strengthened Cu/Co composite oxides (CuCoO) composed of CuCo2O4 and CuO containing multiple Lewis acid sites. The results demonstrate that the as-prepared CuCoO-2 exhibited exceptional activation performance, broad-ranging degradation capacity, remarkable reusability and stability. The optimized CuCoO-2+PMS system achieved complete removal of methylene blue (MB) in 40 min, while maintaining a degradation efficiency of above 86 % even after 5 cycles. A comprehensive survey revealed that hydroxyl radical (·OH), sulfate radical (SO4.-) and singlet oxygen (1O2) collectively contribute to the degradation of MB in the CuCoO-2+PMS system. Especially, 1O2 was the dominant active species. The synergism of various Lewis acid sites (Cu+/2+, Co2+/3+ and VO/N) as unsaturated surface-bound centers played a pivotal role in promoting non-radical-driven activation of PMS. Meanwhile, the generated VO/N facilitated enhanced metallic valence circulation in CuCoO-2, strengthening electron mediation between PMS and MB. Additionally, possible degradation pathways and toxicity evaluations of MB and its intermediates were proposed. In conclusion, this work offers valuable insights into PMS activation by vacancy-strengthened CuCoO and is of great significance for water purification.

Exfoliated g-C3N4-CdS-MXene an efficient all-solid-state Z-type heterojunction serving as efficient photo/electro/photoeletro catalyst for oxygen evolution reaction and dye degradation under visible light at low bias voltage

The rational design of highly active catalysts for the photo/electro/photoelectro catalytic O2 evolution reaction (OER) and water treatment plays a crucial role in the development of sustainable energy generation and environment remediation technologies. Catalysts which are effective in solar light at a low external bias potential are in great demand. Herein, a novel catalyst consisting of all-solid-state Z-scheme g-C3N4-CdS-MXene heterojunction has been designed for photo/electro/photoelectro catalytic reactions. g-C3N4-CdS-MXene exhibited excellent photocatalytic efficiency towards Methylene Blue degradation under simulated solar light irradiation and superb electrocatalytic and photoelectron catalytic efficiency for OER. This catalyst showed high OER performance with an early onset potential of 1.58 V, a low overpotential of 350 mV (at 10 mA cm−2), and low value of Tafel slope (98 mV dec−1). When OER was combined with the photoelectro catalytic reaction for Methylene Blue degradation, g-C3N4-CdS-MXene demonstrated an exceptional photoelectro catalytic performance by degrading 100 % Methylene Blue within 4 min under solar light irradiation at a very low bias of 350 mV. This catalyst also exhibited its capability to degrade various dyes used in textile industries. This work provides an interesting strategy for simultaneous O2 production and efficient dye degradation for environmental and energy engineering.

Unveiling the roles of turbulence characteristics on the degradation of methylene blue by the activation of H2O2 through vortex-based hydrodynamic cavitation under neutral condition

Presently, fast degradation of organic wastewater has been achieved by the synergetic method of hydrodynamic cavitation and H2O2 at a laboratory scale, while the physico-chemical effect, especially the turbulence characteristics on the degradation process remains lacking. This paper presents investigation on the degradation of dyeing wastewater containing methylene blue (MB) under neutral condition, within a vortex-based hydrodynamic cavitation (VBHC) reactor. Operating conditions are firstly optimized and then used to collaborate with H2O2 to study the synergetic effects of this hybrid treatment method. The turbulence characteristics are subsequently obtained by a computational fluid dynamics (CFD) simulation, and the correlation between them and the degradation process of MB is revealed. The results indicate that the highest degradation rate of 91.95 % is achieved under optimal conditions. Higher inlet pressure (4.5 bar) owns the thickest vapor volume fraction, greatest vapor transfer rate, and largest size of cloud cavity in the vortex core region, indicating the strongest cavitation intensity; meanwhile, moderate solution temperature (30 ℃) also favors for the greatest cavitation intensity inside the reactor. The optimal cavitation intensity activates the considerable production of reactive oxygen species, and results in good consistency with the MB degradation performance, which predominately occurs in the annular region around the vortex rope. This research unveils the rationale behind the physical essences of the VBHC process and its influence on the degradation efficacy of MB, which can provide reliable guidance for further development of cavitational reactors to degrade organic pollutants by the VBHC/H2O2 hybrid treatment method.

Analysing the efficacy of TiO2/g-C3N4 nanohybrid electrospun membranes for visible-light photocatalytic water purification

The significance and reliability of membrane-based water purification in wastewater recycling are emphasized in this study. Hydrophilic cellulose acetate and hydrophobic polycaprolactam membranes incorporated with TiO2/g-C3N4 nanohybrids were fabricated by electrospinning. Synthesis of TiO2/g-C3N4 nanohybrids employed a sol–gel-assisted hydrothermal method, while g-C3N4 through fractional thermal polymerization of acetic acid-modified melamine. The optimized photocatalytic hybrid exhibited methylene blue degradation by a 1.5-fold increase in photoactivity compared to pristine TiO2 and a 3-fold increase compared to g-C3N4. Upon incorporation into electrospun membranes, the hybrids demonstrated effective degradation of Methylene blue dye by photocatalysis, and the membranes exhibited excellent stability over multiple cycles.

TiO2-catalyzed photodegradation of methylene blue in a helical FEP tubing reactor: modeling and optimization using response surface methodology

A novel photocatalytic reactor was developed to degrade methylene blue in water using titanium dioxide (TiO2) as a catalyst and fluorinated ethylene propylene (FEP) tubing as a transmitter for ultraviolet (UV) radiation. The reactor was operated by continuously flowing the solution through narrow tubes that were exposed to UV radiation. The efficiency of the reactor was evaluated by comparing it to a previous study that used quartz glass tubing. The study also investigated the effects of flow rate, initial concentration, pH, TiO2 dose and UV radiation without a catalyst on the degradation of methylene blue. The results showed that the FEP tubing was a more efficient UV transmitter than quartz glass. The efficiency of the reactor was also affected by the flow rate and pH of the solution. The highest degradation efficiency was achieved at a flow rate of 10 mL/min and a pH of 7.0. The use of TiO2 as a catalyst also significantly improved the degradation efficiency, with an almost doubling of the degradation rate when compared to the case without a catalyst. This study demonstrates the potential of the FEP tubing-based photocatalytic reactor for the degradation of methylene blue in water. The reactor is easy to operate and can be scaled up for industrial applications.

Ozonation degradation of wastewater using rotational hydrodynamic cavitation reactor with a conical rotor

ABSTRACT Water pollution caused by an abusive discharge of dye-containing wastewater leads to serious ecological risks. Conventional wastewater treatment methods have shortcomings of incomplete degradation, long-time treatment and secondary pollution. For the first time, a rotational hydrodynamic cavitation reactor (RHCR) equipped with a conical rotor has been designed to enhance the ozonation process for effective degradation of pollutants. The effects of rotational speed, discharge voltage, gas flow rate, liquid flow rate and initial pH on methylene blue (MB) degradation were deeply investigated. The optimised conditions were initial pH = 9, rotational speed = 1800 rpm, discharge voltage = 9.3 kV, gas flow rate = 60 mL/min and liquid flow rate = 80 mL/min. With the integration of ozonation and cavitation in RHCR, the MB degradation efficiency reached 95.2%, which was 15.6% higher than that of the individual ozonation method. The degradation process was proven to track the first-order kinetic model, with the reaction rate and synergy index were 0.232 min−1 and 1.78, respectively. Through the quenching experiments, it can be confirmed that the contribution proportion of hydroxyl radical during degradation was increased by 8.7% due to the enhancement of cavitation. A required energy consumption of 74.7 kWh/order/m3 and a total expense of 8.7 $/m3 were calculated. The energy consumption of the RHCR was approximately 80% lower than that of the recently reported degradation system combining ozonation and cavitation, with total expense reduced by 52%. The findings of this work provide a new water treatment method and offered theoretical references for the design of RHCR.

Enhanced Fenton catalytic degradation of methylene blue by the synergistic effect of Fe and Ce in chitosan-supported mixed-metal MOFs (Fe/Ce-BDC@CS)

Methylene blue (MB) is a refractory organic pollutant that poses a potential threat to the aquatic environment. Fenton reaction is considered a primrose strategy to treat MB. However, the traditional Fenton process is plagued by narrow pH application range, poor stability, and secondary pollution. To solve these problems, many Fenton-like catalysts including metal-organic frameworks (MOFs) have been prepared. Herein, a novel bimetallic MOF (Fe/Ce-BDC@CS) was prepared through simple adsorption for the effective removal of MB, where chitosan (CS) was used as the carrier. The degradation performance of Fe/Ce-BDC@CS (100 % within 20 min) was better than that of most reported monometallic MOFs. Moreover, Fe/Ce-BDC@CS exhibited good repeatability and its anti-interference performance of some inorganic ions was also remarkable. Column loading experiments showed that the removal efficiency of MB was still about 50 % over 155 h with a flowing speed of 0.30 L/h. Comparative analysis indicated that such excellent performances could be attributed to the synergistic effect between Fe and Ce. Furthermore, the results of quenching tests indicate that OH, O2−, and 1O2 contributed to MB degradation. In brief, Fe/Ce-BDC@CS has promising prospects in MB treatment, which can provide scientific references for the design and application of bimetallic MOFs.