جستجوی مقالات مرتبط با کلیدواژه « نانوذره های روی اکسید » در نشریات گروه « شیمی »

In this research, spherical ZnO nanoparticles (ZnO NPs) and also ZnO nanoparticles impregnated with Rose Bengal dye (dye/ZnO) were synthesized easily by a new method. The resulting particles with the visible light absorption ability were used as modified photocatalysts for the degradation of phenolic pollutants. ZnO nanoparticles and dye/ZnO were identified with X-Ray Diffraction (XRD) analysis, Fourier Transform InfraRed (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), thermal analysis (TGA/DSC), and UltraViolet-Visible spectroscopy (UV-Vis). The energy gap of dye/ZnO was calculated to be about 2/9eV. Experiments showed degradation of phenol by dye impregnated ZnO nanoparticles under visible light has better efficiency in comparison with the pure ZnO nanoparticles. At the time of 130 minutes, dye/ZnO nanoparticles could degrade approximately 96% of phenol, while the pure ZnO nanoparticles had 10% efficiency at the same time. The mechanism of the reaction is based on the optical excitation of both ZnO semiconductor and dye molecules and then charge transfer.

Copper Oxide(CuO) nanoparticles and nanoporous silica such as MCM-41 and SBA-15 were synthesized and characterized by Fourier Transform InfraRed (FT-IR) spectroscopy, X-Ray Diffraction (XRD), and Sscanning Electron Microscopy (SEM). The synthesized copper oxide nanocatalyst was applied in allylic oxidation of cycloolefinsvia C–H bonds activation by tert-butyl-p-nitrobenzoperoxoate as oxidant and in the presence of nanoporous silica as additive. Allylic esters were obtained in good yields (up to 90%) and reasonable reaction times. Also, the recovered catalyst was applicable in the allylic oxidation reaction for four times without loss in catalytic reactivity and yield. The structure of tert-butyl-p-nitrobenzoperoxoate and allylic esters were characterized by 1HNMR, and 13CNMR spectroscopy

In this study, carbon nanotubes coated with iron oxide nanoparticles were synthesized by a co-deposited simultaneous method with initial salt ratios of 2 to 1 and 4 to 1. In order to study the structural, surface and magnetic properties, electron microscopy, magnetic residue, infrared Fourier transform, Raman, x-ray diffraction, nitrogen adsorption-desorption, and zero-point calculations were studied. The results obtained from the structural analysis indicate that iron oxide nanoparticles with 12.2 nm and 13.5 nm are in the range of 2 to 1 and 4 to 1 on carbon nanotubes, respectively. Also, for these proportions, the behavior of superparamagnetic with saturated magnetization was 11.48 mg/g and 27.97 emu/g, respectively. The results showed that, by choosing the right method and optimizing the effective parameters in the method of synthesis of magnetic carbon nanotubes, it is possible to directly change their surface properties and, as a result, nanostructures with specific surface properties in the “Wide” range of laboratory conditions.

Polyethylene glycols, PEGs, with molar masses of 2000 and 6000 g/mol were dissolved in PEG with a molar mass of 400 g/mol to prepare the homogeneous solutions. Rheological properties and density values for these solutions have been measured. Nanoparticles of MgO were added to these solutions and dispersed by an ultrasonic bath for making homogeneous nanofluids. The UV-Vis spectroscopy, zeta potential, and dynamic light scattering have been used to specify the stability and particle size distribution of colloidal solutions studied. Density values of prepared nanofluids have been measured at different temperatures. The excess molar volumes were calculated from density data for highlighting the interparticle interactions occurred in nanofluids. Polynomial equation and Singh et al. model were used for fitting the excess molar volume values of binary and ternary systems, respectively. Fluid flow and suspense structure of MgO nanoparticles in solutions of PEG400, PEG400-PEG2000, and PEG400-PEG6000 were studied by measuring the rheological properties at T=298.15 K. Bingham plastic and Herschel-Bulkley equations have been used for modeling the dependence of shear stress on shear rate. Carreau-Yasuda model has also been modified for modeling the viscosity values.

This research is on the thermal decomposition of ammonium perchlorate activated by addition of commercial CuO nanoparticles. CuO nanoparticles were characterized by X-Ray Diffraction (XRD) and Transition Electron Microscope (TEM). TEM image shows that the CuO nanoparticles have a nearly spherical morphology. The catalytic activities of the CuO nanoparticles on the thermal decomposition of Ammonium Perchlorate (AP) were evaluated by Thermo-Gravimetric Analysis and Differential Scanning Calorimeter (TGA/DSC), which results show that, in presence of 2 and 5 wt% of CuO nanoparticles, the thermal decomposition temperature of AP decreased by 61.11 and 72.59 °C, respectively. Also, results imply that the heat decomposition of AP was increased by 528.51 and 535.11 J/g in the presence of 2 and 5 wt% of CuO nanoparticles, respectively. TGA data was used to evaluate kinetic parameters of samples by model fitting method and values of A, Ea, ∆G≠, ∆H≠, and ∆S≠ were obtained.