جستجوی مقالات مرتبط با کلیدواژه « wo3 » در نشریات گروه « پزشکی »

Landfill leachate is the fluid percolating through the landfill and is one of the most important environmental challenges that lead to the contamination of water and soil resources. In this study, magnetic graphene oxide nanoparticles with WO3 (GO-Fe3O4/WO3) were synthesized through the hydrothermal method to eliminate chemical oxygen demand (COD) from leachate. The obtained products were characterized using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermogravimetric analysis (TGA), and Vibrating sample magnetometer (VSM) analysis. The influence of various operating parameters, such as initial solution pH, adsorbent dosage, contact time, and temperature, on COD removal was studied. Additionally, kinetic, isotherm, and thermodynamic studies were conducted to evaluate the adsorption capacity of the adsorbent. The results revealed that the maximum adsorption capacity of GO-Fe3O4/WO3 was 2500 mg/g adsorbent at pH 4, a contact time of 90 minutes, an adsorbent dosage of 25 mg g-1, and a temperature below 298 K, respectively. According to the adsorption kinetic fitting results, the experimental adsorption data were well described by the pseudo-second order kinetic with an R2 value of 0.97, and the Freundlich isotherm equation with an R2 value of 0.99. The thermodynamic results indicated that the adsorption was spontaneous and exothermic for COD adsorption. In general, the adsorption process of the synthesized GO-Fe3O4/WO3 nanocomposite revealed that it is highly effective for landfill leachate treatment and has great practical value in leachate treatment.

In the current study, for the first time, an innovative hydrothermal method was proposed for the synthesis of TiO2/WO3 heterojunction nanocomposite from the combination of TiO2 nanorod, and WO3 nanoflakes. Because of environmental issues arising from the vast use of insecticides, this nanocomposite photocatalyst was applied for the first time for photocatalytic degradation of Nitenpyram insecticide under visible light irradiation. The prepared nanocomposite was fully characterized by XRD, FESEM, DRS, PL, and Mott-Schottky analysis. The results revealed that the heterojunction sample had the best photocatalytic performance. The enhanced photocatalytic activity of this heterojunction is attributed to the decrease of the charge carrier’s recombination rate and enhanced visible light harvesting. Moreover, based on the radical trapping experiments and Mott-Schottky calculations, hydroxide radical was determined as the main active species for decomposition of Nitenpyram insecticide, and type II charge transfer mechanism was revealed to be responsible for the enhanced photocatalytic performance, which charge transfer between the two semiconductors results in the decreasing of the charge carrier’s recombination rate.

It has recently been shown that the particle size of materials used for radiation shielding can affect the magnitude of radiation attenuation. Over the past years, application of nano-structured materials in radiation shielding has attracted attention world-wide. The purpose of this study was to investigate the shielding properties of the lead-free shields containing micro and nano-sized WO3 against low energy x-rays.
The radiation shields were constructed using nano and micro WO3 particles incorporated into an EPVC polymer matrix. The attenuation coefficients of the designed shields were evaluated for low energy x-rays (diagnostic radiology energy range).
The results indicate that nano-structured WO3/PVC shields have higher photon attenuation properties compared to those of the micro-sized samples.
Our experiment clearly shows that the smaller size of nano-structured WO3 particles can guarantee a better radiation shielding property. However, it is too early to draw any conclusion on the possible mechanisms of enhanced attenuation of nano-sized WO3 particles.