جستجوی مقالات مرتبط با کلیدواژه « WO3 » در نشریات گروه « شیمی »

Electrochemical oxidation methods are simple, use very few extra reagents, and are both technically and economically viable technologies that can be used for the treatment of various industrial effluent streams including olive wastewater. The treatment is based on the direct anodic oxidation method in which the pollutants are adsorbed on the anode surface and then reduced by the electron transport reaction. In this study, the effect of different catalysts on the treatment of olive wastewater is carried out by using electrocatalytic methods. Initially, TiO2/AC, V2O5/TiO2/AC, WO3/TiO2/AC, and V2O5/WO3/TiO2/AC catalysts were prepared by a sol-gel method. Then, the removal of different pollutants such as color, phenol, lignin, and Chemical Oxygen Demand (COD) was investigated by using different experimental electrochemical processes. In the electrocatalytic oxidation process, synthesized catalytic materials were used as particle electrodes (working electrodes) with the graphite electrodes in an electrochemical cell. The treatment process was optimized by investigating the effects of different parameters, for example, treatment time, catalyst type, catalyst amount (as solid/liquid ratio), voltage, the amount of supporting electrolyte (NaCl), and suspension’s pH. The V2O5/TiO2/AC catalyst exhibited the highest percentage of removal under all experimental conditions, with a significant effect of voltage on the removal capacity observed (82.95% for lignin and 74.42% for COD). While the pH effect showed limited influence on the removal performance, higher yields were observed in acidic conditions. The electrocatalytic reaction involves various steps such as adsorption, nano adsorption, electrooxidation, and electrocatalytic oxidation. The individual effects of these steps were also investigated, resulting in percentage color removals of 25.58%, 51.72%, and 72.42%, respectively. When the data were evaluated in terms of kinetics, it was seen that the data provide a first-degree agreement of over 90 % in all experimental parameters and the removal rate constants of low molecular weight substances may generally be higher than the others. Despite its significant lignin removal efficiency, the catalytic process mentioned above yielded lower values compared to other catalytic methods. Additionally, it was observed that the phenol concentration increased as a result of this process. This suggests that for the catalytic oxidation of olive wastewater effluent, the preliminary treatment using an electrocatalytic process is found to be more effective. The synergistic combination of these processes was more effective than the individual process.

The sol-gel technique is employed for the synthesis of tungsten trioxide (WO3) nanosheets. The Au/WO3 nanocomposite is prepared using laser ablation employing an Nd-YAG laser operating at a wavelength of 1064 nm and utilizing gold metal. The SEM images demonstrate that WO3 was formed as nanosheets with a thickness between 36nm and 80nm.  X-ray diffraction (XRD) patterns confirmed the monoclinic crystal structure and high crystallinity of the WO3 structure. The optical absorption of both WO3 nanosheets and Au/WO3 nanocomposite exhibited a pronounced absorption edge, with an energy gap of 2.52 eV and 2.41 eV, respectively. The photocatalytic activity of WO3 nanosheets and Au/WO3 nanocomposite was determined by degrading Methylene blue (MB) dye under visible light irradiation using different catalyst doses and pH values. The WO3 nanosheets and Au/WO3 nanocomposites that were prepared demonstrate a fast degradation of MB dye. The highest photodegradation efficiency (PDE) of MB dye was 75.9% when 0.05 g of Au/WO3 nanocomposite was exposed to 7 pH for 6 min of irradiation. Nevertheless, an increase of pH led to a corresponding rise in PDE. Particularly, the PDE values reached 85.5% and 95.7% when using 0.1 g of WO3 nanosheets and Au/WO3 nanocomposite, respectively, under the conditions in a pH level of 12 and an irradiation duration of 6 minutes.

In the current study, a novel S-scheme heterojunction photocatalyst was fabricated through a simple hydrothermal method from CeO2</sub> nanoparticles and WO3</sub> nanoplates in presence of tragacanth mucilage as natural surfactant. The prepared heterojunction photocatalyst was used for degradation of Nitenpyram insecticide under visible light irradiation. The successful synthesis of the heterojunction samples was confirmed by FESEM, XRD, PL, DRS, and Mott-Schottky analysis. The results showed that, the photocatalytic performance of the CeO2</sub>/WO3</sub> heterojunction sample was higher than that of the pure WO3</sub> and CeO2</sub> samples. The highest photocatalytic activity was obtained for the sample with 30 wt% CeO2</sub> content, which has the reaction rate constant of 0.017 min-1</sup>. The improved photocatalytic activity of the nanocomposite sample could be related to the efficient separation of the photoinduced electron-hole pairs at the interfaces of WO3</sub> and CeO2</sub>, and enhanced visible light harvesting. Furthermore, according to the active species trapping tests and Mott-Schottky measurements, hydroxide radical was determined as the main active species for degradation of Nitenpyram insecticide, and a S-scheme charge transfer mechanism revealed to be responsible for the enhanced photocatalytic performance.

One of the most important problems in the oil industry is the presence of sulfur and sulfur compounds in crude oil. Sulfur compounds in crude oil can have detrimental effects on the environment, equipment, catalysts, and end products. One of the most important goals of researchers in recent years is to sweeten petroleum products from these compounds. This study aims to use NiWO4/W5O14/WO3 composite nanostructure to solve this problem using the photocatalytic oxidative desulfurization method. This composite nanostructure has been synthesized by Pechini sol-gel method with high purity at low temperature and examined by XRD, EDS, FESEM, and FT-IR analysis. Due to the presence of WO3 in the composition, the bandgap was greatly reduced and the efficiency was increased. As a result, the nanostructure could degrade more than 73% of the sulfur in thiophene in 180 min under visible light. By optimizing the amount of photocatalyst and irradiation time, the efficiency can be improved.

The aim of this study was to evaluate the efficiency of Ag/WO3 photocatalytic process for degradation of Flumequine (FL) antibiotic from aqueous solutions. In this study, WO3 and Ag/WO3 particles were synthesized and characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS)/Map, Brunauer, Emmett, Teller (BET)/Barrett, Joyner, Halenda (BJH) and UV–vis diffuse reflectance spectroscopy (DRS) techniques. The photocatalytic degradation of FL from aqueous solutions was studied by Ag/WO3 photocatalyst under sunlight irradiation. The response surface methodology (RSM) with Central Composite Design (CCD) with 4 variables was used to investigate the relationship between the obtained responses and process variables and optimize with Design Expert software. In this study, the effect of pH, time (min), photocatalyst mass (g) and FL concentration (mg/L) were evaluated at 5 levels. Finally, the software is the best point to achieve the highest degradation efficiency of FL 99.54%, in optimal conditions at pH 3.07, time 101.14 (min), photocatalyst mass 0.13 (g) and FL concentration 41.3 (mg/L).

The aim of this study was to investigate and overcome thiophene sulfurcontaminants using high purity synthesized ZnO/WO3 nanocomposite andhomogeneous composition by Pechini sol-gel method at low temperature.Zinc oxide is one of the most dynamic elements known in this field, itspresence together with tungsten oxide prevents the crystallization of tungstennanoparticles. Fuzzy structure, percentage of elements, surface morphology,penetration reflection spectrum, and photocatalytic degradation of thiophenewere determined by XRD, EDS, SEM, and DRS analyses, respectively. DRS resultsindicate high light absorption, reduced bandgap due to the presence of WO3 aftercombination with ZnO, and increased efficiency. Finally, the nanocomposite withmore than 84% efficiency resulted in the degradation of oxidative desulfurizationof thiophene after 150 min under visible light.

In this work, hierarchical WO3 core-shell microspheres were synthesized via a facile template-free precipitation method. Gas sensing properties of the synthesized powder to acetone and some other volatile organic compounds were comparatively investigated with commercial WO3 nanoparticles. The synthesized and commercial powders were characterized by X-ray diffraction, scanning electron microscopy, particle size distribution analysis, Brunauer–Emmett–Teller and Barrette-Joyner-Halenda techniques. Gas sensors were fabricated by deposition of powders between/on interdigitated electrodes via sedimentation approach. The results show that both sensors are sufficiently sensitive to detect 1.8 ppm of acetone; diabetes diagnosis threshold in human exhaled breath. Indeed, the hierarchical based one is highly sensitive and more selective to acetone.

Tungsten trioxide nanoparticles with monoclinic structure and average particle size about 80 nm were prepared by the spray pyrolysis method. WO3 nanorods with hexagonal structure and average dimension about 15 × 100 nm were synthesized in gram quantities by modified hydrothermal method at lower temperature and shorter reaction time in comparison to the previous research. Photo degradation of Congo Red showed that the as-prepared WO3 nanoparticles is more effective than nanorod structure. WO3 nanorods actually had no effect in Congo Red photo degradation. Therefore in this reaction, spherical morphology is superior to column morphology. The samples were characterized with X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), EDX analysis, UV-visible spectrum and Transmission Electron Microscopy (TEM).