جستجوی مقالات مرتبط با کلیدواژه "تیتانیم دی اکسید" در نشریات گروه "شیمی"

In this study, ZnO/TiO_2 : Ag composite fibers were prepared by a simple stretching method. The prepared fiber nanocomposites' structural, optical and photocatalytic properties were investigated. X-ray diffraction (XRD) results showed that the structure was successfully synthesized. Scanning electron microscopy (SEM) images showed that the diameter of the prepared fibers was about 10 micrometers. Fourier transform infrared (FTIR) spectroscopy and EDX energy scattering confirmed the strong bonds of the relevant elements and their presence in the composite structure. Increasing the calcination temperature improved the structure and purity of the composite. The photocatalytic performance of nanofiber composites for the degradation color of methylene blue (MB) under UVA light was studied. It was observed that the prepared nanofibers have suitable physical-optical properties and photocatalyst properties (98%) under UVA light exposure in 100 min for the treatment of industrial wastewater containing dyes.

The release of heavy metals into the environment due to industrialization and urbanization has caused major problems throughout the world. Increasing the pollution of the environment by heavy metals due to carcinogenicity and biological accumulation has caused serious concerns. Therefore, the adsorption of heavy metals from industrial wastewater is one of the important environmental issues. Lead is one of the four metals that have the most effect on human health. So far, different methods have been considered for adsorbing lead. The use of biocompatible adsorbents is one of these methods. Montmorillonite (MMT), a clay mineral with unique physical and chemical properties are considered a biocompatible adsorbent. In this study, after modification of the surface of the MMT by titanium dioxide was characterized by FT-IR, XRD, FE-SEM, and BET techniques. Then the activity of the MMT nano-adsorption immobilized on the surface of titanium dioxide (TiO2/MMT) was investigated for the removal of lead (II) ion and different factors such as contact time, adsorbent dosage, lead (II) ion concentration, and pH were optimized. The efficiency of this nano-adsorbent is such that even in the presence 10 mg can eliminate a significant amount of lead ion (II) (50 ppm) with a yield of about 90% at neutral pH over a short period of time (5 minutes). Moreover, the experimental results showed that the adsorption capacity of Pb2+ ion by TiO2/MMT decreased by only about 8-10 % after performing 12 runs of the adsorption process.

In this study, titanium dioxide (TiO2) containing 1 wt% of various elements (Ag, Cr, Cu, V, or Pt) was synthesized by a one-pot sol-gel method. The produced materials were extensively characterized by means of X-ray diffraction (XRD), BET surface-area measurements, Raman spectroscopy, UV-Vis spectroscopy and Transmission electron microscopy (TEM). UV-Vis spectroscopy demonstrated a clear shift in the absorbance of modified TiO2 towards the visible light region. The photocatalytic performance of the prepared materials was evaluated in the photooxidation of methylcyclohexane (MCH) under the illumiation of UV or Visible light. The performance was monitored by in situ ATR-FTIR. The best catalytic performance was obtained when Cr/TiO2 was applied. The photocatalytic activity under visible light illumination could be further enhanced by photodeposition of Pt nanoparticles (0.06 wt % Pt) on the surface of Cr/TiO2. The origin of the synergetic effect of Cr6+ and Pt nanoparticles will be discussed.

Antifouling properties of mixed matrix polysulfone (PSF) and modified Halloysite NanoTube (mHNT) nanoparticles ultrafiltration membrane were studied. The membranes were fabricated with different concentrations of mHNT and PSF by phase separation method. Pure water flux, protein removal, and fouling parameters for analysis of membrane performance were studied. The HNTs nanoparticles tructure was modified by TiO2 and its structure was determined by TEM and XRD. The membrane structure was studied using Scanning Electron Microscopy (SEM). The water flux of the nanocomposite membrane was improved significantly From 140 to above 350 L / m2.h at 5bar pressure with the improved hydrophilic property. The hydrophilic properties were confirmed by measuring the contact angle and the porosity. This improvement is due to functional groups in the hydrophilic property that can be attributed mHNT and TiO2 nanoparticles. The sedimentation of the membrane, resistance was investigated by the Bovine Serum Albumin‎ (BSA). The results of membranes with 0.5 and 1% loading of mHNT exhibited the best anti-fouling properties which is leading to 100% flux recovery. The results also show that the membranes with 0.5-1 wt% mHNT loading is the highest porosity and water flux.

The world´s population is rising and supplies of drinking water are declining. Water pollution by pesticides is considered as one of the environmental problemsand the removal of pesticides from water sources has been of interest to researchers. One of the methods for removing toxins from water sources is the use of catalyst and photocatalyst materials. One of the most widely used materials in this field is titanium dioxide, which has been one of great interest to researchers for its photocatalytic properties. Studies have shown that this substance is used to remove phenol. However, few studies have been carried out to remove Carbendazim. In this research, it has been attempted to study and analyze the conditions for removal and degradation of Carbendazim as a pollutant by obtaining a catalyst based on titanium dioxide with a nanostructure. For this purpose, Titanium dioxide nanoparticles were synthesized by sol-gel methodand some copper was added as a pollutant. To identify and study the X-ray diffraction patterns XRD, scanning electron microscopy SEM, infrared IR spectroscopy, porosimetry BET, ultraviolet-visible spectroscopy UV-VIS and energy X-ray Diffraction EDX was used. The results showed that the synthesized nanoparticle size was about 40-50 nm and the morphology of particles is spherical. The synthesized catalyst at 400 ° C had anatase phase. The anatase phase of this material was used for degradation of Carbendazim under photocatalytic conditions and the pH parameter was also optimized. In fact, with the increase of the copper impurity at the value of 0.5 gr, the optical band gap has decreased and the absorbance has been shifted to the bulkier wavelengths. So, titania-copper composite with anatase phase and degradation of fungicidal Carbendazim with 88 yield, it can be used as a nanostructure photocatalyst for the removal of water pollutants.

In this present study, was investigated the phase transition of pentylcyanobiphenyl (5CB) 55% and heptylcyanobipheny (7CB) 45% (E5CN7) doped with 1% TiO2 and Fe3O4 by using Differential Scanning Calorimetry (DSC). The Nematic-Isotropic (N-I) phase transition temperature shifted to lower temperature 1.04 and 1.41 K for TiO2 and Fe3O4 respectively. For the understanding of effective parameter on the N-I phase transition temperature was used mean field theory. Was observed good agreement between theoretical and experimental resulted. In the second was studied of electrical behavior of E5CN7 in present both of NPs, the results shows value of diffusion and ion mobility reduce in present of NPs (specially of Fe3O4). Also the resistance is reduce and conductivity increases.

In this study, in order to surface modification of zinc oxide, titanium dioxide and boehmite nanoparticles the new organic compound was introduced. Creating new functional groups with oleic acid did not represent the satisfactory results, so in this work, the oleic acid was turned to the much more active compound, and then on the surface of the mentioned nanoparticles was assembled. The novel reagent named N-(3-triethoxysilylpropyl) oleamide (N-TESPO) was synthesized through chemical modification of oleic acid which easily capable of functionalizing a variety of oxide nanoparticles to superhydrophobic nanoparticles. This reagent was synthesizedin a two-stage reaction of oleic acid. To investigate the properties of the superhydrophobic nanoparticles with the chemical surface modification method, the contact angle test, SEM and FTIR were applied. The results of the water contact angle tests illustrated that the water contact angle of the surface covered with the modified zinc oxide, titanium dioxide, and boehmite nanoparticles was 158°, 163°, and 161°, respectively that proved the superhydrophobicity characteristic of this modified nanoparticles.

The effect of three commercial types of titanium dioxide (TiO2) with primary particle sizes of 20 to 50 nm have been used for different sunscreens formulations. The efficiency of these sunscreens formulations, such as Sun Protection Factor (SPF), UVAPF and critical wavelength (λc) were tested. Oil/water creams with 5%, 10%, and 20% concentrations of each type of TiO2 were prepared, and SPF, UVAPF and λc were measured using both in vitro and in vivo methods. Because the samples have been aggregate and made the agglomerations, the milling and hemogenation methods have been used for decrease size of particles. In vitro analysis demonstrated that submicron-sized TiO2 cream had a lower SPF value than nanosized TiO2 formulations of the same concentration. In vivo experiments confirmed this result, and a strong correlation between in vitro and in vivo measurements was observed. Furthermore, the SPF values of nanosized TiO2 sunscreen were concentration-dependent in the range of 5% to 20%. Scanning electron microscopy results indicate that the higher SPF of nanosized TiO2 formulations may be due to the formation of multilayer agglomerates by small particles at nano-scales, leading to a reduced void space between particles and a more efficient barrier to protect skin from sunlight.

In this research, a titanium dioxide thin film with average particles size of 8 nm was prepared on glass surface and then it's crystalline and optic properties before and after calcinations was investigated. Low angle XRD analyses showed that prepared thin film has mesoporous structured prior to calcination and a further increase in the meso-scale order has been made by calcination. Low angle XRD analyses revealed three peaks related to hexagonal symmetry before and after calcination. Lattice constant of the prepared titanium dioxide before and after calcination, using miller indices of (100) crystal plane calculated to be 147.57 and 143.47 Å, respectively. Transmission spectra of titanium dioxide coating exhibit a significant blue shift in absorption edge and increasing of its transparency after calcination. Indirect band gap of prepared coating estimated from UV-Vis spectra to be 3.69 eV and refractive index of the film and its porosity percentage was calculated to be 1.54 and 67%, respectively.