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In the present work, the heterogeneous Fenton-like process was employed to investigate the kinetic models of the degradation of methyl orange (MO) using tungsten oxide/hydrogen peroxide couple. Tungsten oxide particles were successfully synthesized by reflux without surfactant and characterized by using XRD, SEM, TEM, and FT-IR techniques. The infl...
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... The BEs of O1s spectra fit into two components located at 530.493 and 532.178 eV associated with the lattice oxygen (i.e., W-O-W), and adsorbed oxygen (proximity of oxygen vacancy), respectively [11]. The peak at 530.493 (±0.1) eV corresponds to the O 2− oxygen bond with W 6+ atoms, also, the peak at ~532.178 (±0.1) eV is attributed to the bonds with tungsten in lower oxidation states due to a small amount of water containing h-WO 3 [13,35]. The XPS spectra of C1s reveal the adventitious carbon peak observed at ~284.6 (±0.2) associated with the C-C bond. ...
One-dimensional (1D) nanostructures are extremely important due to better charge transport capabilities. The ability to anchor 1D semiconductor nanostructures on graphene may give advantages in electrochemical charge storage applications. In this study, the authors explored the synthesis, growth mechanism, and insertion-type pseudocapacitive properties of 1D hexagonal (h) phase-WO3 (h-WO3) nanopillars and h-WO3/rGO nanocomposite. The nanocomposite is composed of h-WO3 nanopillars uniformly grown on a reduced graphene oxide (rGO) matrix and the resulting h-WO3/rGO nanocomposite shows the hexagonal structure and, 3D networks gathered during a hydrothermal process. XRD confirms the phase purity and crystalline nature, SEM confirms the hexagonal bundled nanopillar morphology of h-WO3 and its graphene composites, and rGO offered crumpled two-dimensional sheet-like morphologies. HRTEM and SAED analysis confirmed the highly oriented growth of h-WO3 nanowire along the [001] zone axis. XPS analysis confirms the presence of tungsten in +6 and + 5 oxidation states, indicating the formation of the oxygen-deficient h-WO3-x structure. The electrochemical characterizations are performed using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS), and stability tests. From the CV measurements, the outperformed exceptional h-WO3 and h-WO3/rGO nanocomposites exhibit specific capacitance (Csp) of ∼545 Fg⁻¹ and ∼926 Fg⁻¹, respectively, at a 5 mVs⁻¹ scan rate, and from GCD measurements Csp found to be ∼504 Fg⁻¹ and ∼991 Fg⁻¹, respectively at 0.1 Ag⁻¹ current density. Supercapacitor capacitances with carbon and metal oxide electrodes are typically related to the accessible surface areas. However, this work indicates that proton insertion, a rare capacitive charge storage mechanism, may significantly increase the capacitance of metal oxides with a limited surface area but a particular structure. Nonetheless, using the proton insertion process, scientists have shown that the electrodes made from an assembly structure of h-WO3 nanopillars have enhanced charge storage performance. According to detailed investigations, the electrochemical behavior of h-WO3 is dominated by the proton insertion mechanism and is critical in achieving high capacitance by eliminating alternative mechanisms. This research work presents a novel method for attaining extraordinary charge storage contribution into the ordered tunnels in crystalline metal oxides due to efficient proton insertion, which is especially significant for the construction of high-performance electrochemical energy storage systems: batteries and supercapacitors.
... In the strong acid media, it was possible to oxidise more than 97.8% of methyl orange [19] using Fenton reaction. According to previous work, tungsten oxide used as a heterogeneous Fenton-like catalyst resulted in a good efficiency in the degradation of methyl orange and indigo carmine [20,21]. However, these works involving this heterogeneous system for the removal of recalcitrant dyes did not elaborate on the kinetic models of their studies. ...
... is value of pH was previously observed as an optimal condition to remove MO [20]. e removal rate of MO decreased around 3% when WO 3 was as used the catalyst. ...
In the present work, the heterogeneous Fenton-like process was employed to investigate the kinetic models of the degradation of methyl orange (MO) using tungsten oxide/hydrogen peroxide couple. Tungsten oxide particles were successfully synthesized by reflux without surfactant and characterized by using XRD, SEM, TEM, and FT-IR techniques. The influence of parameters such as temperature and concentration of MO was studied and pseudo first-order and second-order models were applied. WO3/H2O2 showed high efficiency in the removal of methyl orange and attained more than 92.8% in 180 min. The first-order kinetic model was described by the removal process with the correlation coefficient of R2 = 0.99.
... The reactive species produced are traditionally recognized as hydroxyl radicals, though other substances such as ferryl-ions (also products of this reaction) (Deng and Zhao, 2015). In addition to Fe 2+ ions, the oxidizing solution may contain other metal ions, e.g., Cu + , Cr 3+ , Co 2+ , Ti 3+ , W 6+ , Mo n+ , etc., that can catalyze similar (Fentonlike) reactions (Wang et al., 2016;Zhang et al., 2018;Séverin et al., 2020). Remarkably, bimetallic Fenton reagents demonstrate a higher catalytic efficiency compared to the homogeneous Fe(II)-based catalysts. ...
In many countries, the textile industry remains the major contributor to environmental pollution. Untreated textile dyes discharged into water negatively impact the performance of aquatic organisms and may cause a variety of serious problems to their predators. Effective wastewater treatment is a key to reducing environmental and human health risks. In this work, the Fe/Cu catalysts were used in heterogeneous Fenton’s reaction for the degradation of high concentrations of methyl orange (model azo dye) in aqueous solutions. For the first time, the catalysts were prepared onto commercial copper foams by potentiostatic electrodeposition of iron using an environmentally friendly electrolyte. The influence of electrodeposition conditions, H2O2 concentration, dye concentration and temperature on the model dye degradation was investigated. It was revealed that both the surface area and the catalyst loading play the major role in the effective dye degradation. The experimental results involving spectrophotometric measurements coupled with total carbon and nitrogen quantification suggest that a solution containing up to 100 mg/L of methyl orange can be successfully decolorized within 90 s at 50°C using porous Fe/Cu catalyst in the presence of hydrogen peroxide that largely surpasses the current state-of-the-art performance. Already within the first 10°min, ∼ 30% of total methyl orange concentration is fully mineralized. The described process represents a cost-efficient and environmentally friendly way to treat azo dyes in aqueous solutions.
