جستجوی مقالات مرتبط با کلیدواژه « titanium dioxide » در نشریات گروه « مواد و متالورژی »

The aim of this study was to prepare titanium dioxide nanoparticles calcined at different temperatures to be used for adsorption of zinc ions from aqueous medium and then to investigate the kinetics and isotherms of the adsorption process. For this purpose, nanoparticles were synthesized using the sol-gel method and then calcinated at 450 °C and 800 °C. XRD, BET, FTIR, and SEM analyses were used to investigate the structural, surface, and chemical properties of the synthesized nanoparticles. Adsorption studies revealed that the solution containing zinc with an initial concentration of 10 mg/l had the highest adsorption efficiency under conditions of pH = 7, adsorbent concentration of 0.3 g/l, and temperature of 25 ° C. Under these conditions, adsorbents prepared at 450 °C and 800 °C achieved 99% and 92% adsorption efficiencies, respectively. Adsorption isotherm studies revealed that the Freundlich, Temkin, Langmuir, and Dubinin–Radushkevich isotherms had the best agreement with equilibrium sorption data, in that order. In addition, investigations on fitting into kinetic models revealed that the quasi-second-order, Elovich and the quasi-first-order equations had the best fit with experimental data, respectively.

In this Paper, the structural, electronic and optical properties of TiO2 compound are investigated and calculated.The calculations were performed using the full potential linear augmented plane wave (PP-PW) method within density functional theory (DFT)and using the Wien2k package.Structural properties such as lattice constants, bulk modulus and compressibility of this combination are calculated and are well compatible with existing experimental values.The presence of a band gap is the reason why it is semiconductor.The study shows that in some points of the energy interval, it has a negative value. Therefore, no waves are emitted in the composition in this energy range.In addition to the optical properties of this compound, due to its importance in the industry, its high refractive index was investigated.

In this study, structural characteristics and linear and nonlinear optical properties of TiO2/ZnO nanocomposite were investigated. In the first step, TiO2/ZnO composite nanostructure was prepared via a two-stage chemical coprecipitation approach by adding TiO2 nanoparticles into an aqueous solution containing zinc acetate precursor. In a second step, pure TiO2 and ZnO nanoparticles were synthesized by a co-precipitation method to investigate the presence portion of the basic structures on linear and nonlinear optical properties of TiO2/ZnO nanocomposite. Phase identification and chemical analysis of assynthesized nanostructures were performed by X-ray diffraction (XRD) crystallography and Fourier transform infrared (FT-IR) spectroscopy. Elemental properties of samples were studied by energy dispersive X-ray spectrometer (EDS) and surface mapping recorded by field emission scanning electron microscopy (FE-SEM). The morphological studies of the as-synthesized nanocomposite were analyzed by transmission electron microscopy (TEM). Linear optical studies were carried out to achieve the optical absorption edges and band-gap energies using UVVis spectra. Standard single-beam Z-scan technique with open-aperture (OA) and closed-aperture (CA) setups was utilized to determine nonlinear refraction index and nonlinear absorption coefficients, respectively. The optical nonlinear results showed a third-order optical susceptibility from the order of 10-4 esu under 532 nm laser radiations. 

In this research, the influence of titanium dioxide nanoparticles on the structural and magnetic properties of high-temperature superconductor Bi1.6Pb0.4Sr2Ca2Cu3O10+θ (Bi-2223) from the Bi-based ceramic system  (BSCCO) was studied. In order to investigate the synthesized samples, X-ray diffractometry and magnetic measurements were performed. Based on the magnetic measurements, the superconductivity transition temperature declined with the increase in the nanoparticleschr('39') content. The addition of nanoparticles affected on the hysteresis loop width. Accordingly, the compound containing 0.2 wt.% nanoparticles had the maximum magnetization,  hysteresis loop width, and critical current density.

In this study, tiles were coated with TiO2 and TiO2-Ag in different weight percentages by sol-gel and immersing method. The structural characteristics of the samples by XRD and EDS showed the rutile phase of TiO2 and Ag2O3. Microstructural studies using FESEM showed that the grain size decrease d with increasing of titanium dioxide and silver nitrate. The antibacterial properties of the samples with different amounts of silver nitrate and titanium dioxide were investigated by two types of gram-positive bacteria Staphylococcus aureus ATCC 6538 and gram-negative bacteria Escherichia coli ATCC 25922 under visible light. The results showed that the percentage of reduction of S. aureus and E. coli bacteria by TiO2-Ag coatings was 99% and 98%, respectively. The wettability behavior of the coatings was obtained by measuring the contact angle. Doping silver nanoparticles with titanium dioxide reduces the contact angle and the samples behavior changes from hydrophilic to super-hydrophilic.

Given the growing importance of photocatalysts in the industrial wastewater treatment, in this study, TiO2-CuO (TC) composite nanoparticles were synthesized by sol-gel method. Tetrabutyl orthotitanate (TBT), copper nitrate-3hydrate and ethanol were used as titanium dioxide precursor, copper oxide precursor and solvent, respectively. The structural, optical, photocatalytic activity and BET-BJH properties of nanoparticles were studied by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), UV-Vis absorption spectroscopy and Brunauer-Emmett-Teller specific surface area (BET). The results of XRD and BET analysis show that the TiO2-CuO composite reduced the crystallite size and increased the specific surface area. Also the results of XRD, EDX, and MAP analysis confirmed the presence of TiO2, CuO in the nanocomposite. The specific surface area for the pure mesoporous titania (T) and TiO2-CuO (TC) nanocomposite samples are 60.25 282 m2/g and 163.22 m2/g, respectively. Absorption edge (λedg) and band gap energy (Eg) of T and TC samples are 365.7 nm, 3.39 eV and 375 nm and 3.30 eV, respectively. The results of FESEM showed that the particles were somewhat agglomerated and the particle size of the composite sample was 10-15 nm.

In this research, a reliable and simple method was described for the determination of the amount of titanium dioxide (TiO2) in double base solid (DB propellants), based on a comparison with the inductively coupled plasma method. The method is based on complex formation of Ti(IV) with chromotropic acid in acidic media and monitoring the absorbance of the colored products by spectrophotometric technique at 460 nm. Under optimal conditions, the calibration graph was linear in the range of 0.10-5.0 μg mL-1 of Ti(IV) with the limit of detection of 0.05 μg mL-1. The validity of the method was evaluated by means of the data statistical analysis. For this purpose, the method was applied to the determination of titanium dioxide in DB propellants, and the results were compared based statistical tests with those obtained by the ICP- AES. The results showed that the proposed method offers an accurate and reliable approach for the determination of TiO2 in DB propellants, and can be suggested as a routine method in quality control laboratories.

Sodium potassium niobate piezoceramics are considered as lead-free piezoelectric due to their good properties. In this study, the effect of titanium dioxide and molybdenum oxide as dopant on the densification behavior, piezoelectric and dielectric properties of lithium doped sodium potassium niobate ((K0.5Na0.5)0.94Li0.06NbO3, KNNL) was investigated. For this purpose, (K0.5Na0.5)0.94Li0.06Nb0.99X0.01O3 (KNNL-X, X= Mo, Ti) ceramics were synthesized by solid state reaction method. The results showed that the use of these dopants improves the densification of KNNL ceramic, which could be attributed to the increased diffusion due to creating the oxygen vacancy defect. The decrease in the piezoelectric coefficient of KNNL ceramic in the presence of dopants can be attributed to the hardening behavior of the piezoceramic due to the existence of oxygen vacancies. The increase in dielectric constant and decrease in dielectric loss of doped samples can be attributed to the increase in density and decrease in porosity. KNNL-Mo samples showed the lowest piezoelectric coefficient and the highest dielectric constant values.