Sharif Digital Repository

UF membranes are widely used in various industries now, a major type of these membranes are ceramic membranes which are resistant to high temperatures and corrosive fluids. In this thesis we developed an anisotropic UF ceramic membrane based on 20nm TiO2 nanoparticles on a prous sustrate. We had two major challenges, the first one was to find a suitable prous substrate and the second one was to find an appropriate coating method. Our main task was to optimise the process conditions to achive a crackless and uniform membrane layer with minimal ups and downs. Lots of coating methods and TiO2 inks have been tried, finally we used a coating method which we called it “Soft Blade Coating”, with... 

This study presents a facile sol-gel template-assisted route to prepare CNT-TiO2 hybrid structures (CTH) for dye-sensitized solar cell (DSSC) applications. Non-covalent functionalized multi-walled carbon nanotubes (CNTs) with average diameter of 80 nm are used as the template for TiO2 deposition. The X-ray diffraction reveals that the hybrid structures are composed of primary anatase TiO2 nanoparticles with the average crystallite size of 12 nm, after heat treatment at 450°C in air atmosphere. TEM and FESEM images show that the shell thickness of the coated TiO2 on CNTs’ outmost walls varies between 60 to 120 nm, when the ratio of CNTs:TiO2 is 10wt. %. Photovoltaic measurements demonstrate... 

Different types of morphologies and phase structures of crystalline TiO2 were synthesized by hydrothermal methods. For the first time, dandelion-like rutile TiO2 powder composed of numerous single crystalline nanorods was synthesized using TiCl4 as the main precursor. TiO2 Nanoparticles were produced using TTIP and 2-propanol, as precursor and solvent, respectively. Field emission scanning electron microscopy analyses revealed that the synthesized TiO2 nanoparticles had average crystallite size in the range 21–70 nm, whereas dandelion-like TiO2 showed diameter in the range 2-10 µm. According to the significant refractive index of TiO2, in particular rutile phase, it can be used in the... 

One of the basic resources for lithium extraction is brine which is very abundance in Iran. It is important to characterize these brines and their compositions to select a suitable method for lithium recovery from them. By investigation of the local brines and determining lithium and other alkali metals composition in them, the ion exchange process using titanium dioxide ion-sieve with nanotube morphology is suggested as highly effective method for lithium extraction from Iranian brines. Due to high advantages of hydrothermal process, TiO2 nanotubes were produced by this method and the optimum parameters of hydrothermal reactions were reported. In this way, hydrogen titanate nanotubes with... 

This thesis is concerned with the synthesis and characterization of high porous Ti based on thin films and the effect of polymer agents on their photocatalytic properties. Ti films can demonstrate different properties like self -cleaning and treatment of broad range of aqueous pollutants when it is exposed to light of wavelength less than 400 nm. This is due to photocatalytic reaction occurring on film surface which results in film superhydrophilicity and the active oxygen species production. This active sites and radicals will cause oxidize organic pollutants and microbe adherent to the material surface.
In this study Ti thin films have been prepared by the sol-gel method from... 

The present work describes sensing application of modified Pt nanostructures towards detection of glucose. Modified Pt nanostructured electrodes were prepared using electrodeposition method such as chronoampermetry and potentiostatic pulse methods. The electrodeposition of Pt nanostructures was first studied by voltammetry and amperommetry techniques and then potentiostatic pulse method has been used to produce the alloyed structures of platinum. In this regard, the first electrode was proposed based on alloyed Pt/Ni nanowire arrays (NWAs) for the non-enzymatic detection of glucose. The Pt/Ni NWAs were prepared by pulse electrodeposition of Pt and Ni within a nano-pore polycarbonate (PC)... 

The present work describes sensing application of modified TiO2 nanotubes towards detection of dopamine. The TiO2 nanotubes electrode was prepared using anodizing method at different conditions, among which NaF/ NaHSO4 solution and voltage of 15 V was chosen as the optimum condition. In order to improve the performance, surface modification with metal nanoparticles (Pd, Pt and Au) and carbon is required using “pulse electrodeposition” and “decomposition of polyethylene glycol at 600 °C” respectively. Carbon was deposited by decomposition of polyethylene glycol in a tube furnace to improve the conductivity. In this regard two type of electrodes were proposed: Pd-Pt-Au-TiO2 and C-Ni(Pt)-TiO2.... 

Titanium dioxide has covered a wide range of applications as a semiconductor photocatalyst. TiO2 is an indirect, 3.2 eV band gap semiconductor which can be stimulated using UV light. Improving the quick electron-hole recombination rate, we can enhance the photocatalytic efficiency of this semiconductor. One of the approaches in hand is to use noble metals in connection to TiO2. Among noble metals, due to its plasmonic and anti-bacterial properties and ease of preparation, silver would serve as a perfect candidate. The mechanism for photocatalytic enhancement in Ag-TiO2 structures lies behind the fact that silver can trap the photogenerated electron of TiO2 and inhibit the electron-hole... 

In this study, pulse electrodeposition of Ni-Fe composite coating with and without nano-TiO2 particle in sulphate bath was performed and effects of peak current density, frequency, duty cycle and type of current on their properties was investigated. Also effect of pulse parameters on the composition and amount of particles in coatings was determined. Scanning Electron Microscopy (SEM), Field Emission Scanning Electron Microscopy (FESEM) and X-ray Diffraction (XRD) analysis was used to study the morphplogy and structure of coatings. The chemical composition of deposits was examined by Energy Dispersive X-ray Spectroscopy (EDS) attached with Scanning Electron Microscopy and Atomic Adsorption... 

Tungsten Inert Gas (TIG) process and different cored wires that were filled separately with nano TiC particles, micro TiC particles and graphite powders were employed to produce surface composite coating on CP-Ti substrate to improve wear resistance. At first using titanium strips, wire drawing process and different powders various cored wires were produced and then using TIG, these cored wires were coated on CP-Ti. This process was done for different current intensities and velocities. Composite coating tracks were found to be affected by the TIG heat input and the kinds of the cored wires. The microstructures of the surface composite coating showed phases of α'-Ti and primary and dendritic... 

TiO2 and TiO2-Graphene have been synthesized by hydrothermal method. Their physical, chemical and morphological properties have been investigated using XPS, XRD, FTIR, TEM, EDX, UV-Vis and AFM analyses. Moreover, photocatalytic efficiency of prepared materials has been examined using degradation of methylene blue. AFM image exhibited that monolayer GO with thickness of 10 nm was synthesized using modified Hummer’s method. FTIR analysis represented main characteristic peak of oxygen bond on the surface of GO, whereas for TiO2-Graphene most of oxygen functionalities on the surface were removed partially or completely. Photocatalytic degradation of MB proved this extension of light absorption.... 

In recent decade, photocatalystic properties of titania nanotube and its mechanisms has been considered greatly in many researches. One of the major ways to increase photocatalystic properties and extending the usage of TNTs is doping them with various elements and modifying their band structure. In present research doped TNTs were prepared by doping of Molybdenum, Nitrogen, and Carbon elements by anodizing method in about of 35 degrees of centigrade and constant voltage of 20V on the surface of titanium sheet. Structural and photocatalystic properties of as-prepared TNTs were studied using field emission scanning electron microscope (FESEM), x-ray diffraction (XRD), energy dispersive... 

Basically, it is required that the materials used as electrical contacts should have good thermal and electrical conductivity and certain strength. The copper base composites with fine TiO2 particles as reinforcement have almost identical electrical and thermal conductivity with copper; in addition, they have the advantage over pure copper in high strength owing to the dispersion of the fine TiO2 particles, which improve copper matrix strength through impeding dislocation movement. In this present work, at the initial stage, Cu and Ti powders were mechanically alloyed for 60h under Argon atmosphere, and then added Cu2O powders as oxidant. The specimens, containing different amounts of TiO2,... 

In this project, The cadmium sulfide nanoparticles were formed on a nanostructured and meso-porous titanium dioxide layer and its properties were characterized. Deposition process of titanium dioxide and cadmium sulfide has been performed respectively in one stage and two stages of dipcoating. In order to probing effects of temperature and dipcoating time, samples have been prepared in various times and temperatures. Also, some of the samples have been annealed. Thickness of titanium dioxide and cadmium sulfide coatings were approximately measured 1 μm and between 3-5 μm, respectively. As expected, XRD results disclosed that cadmium sulfide and titanium dioxide were formed in the form of... 

The Dye-sensitizers loading on TiO2 is decreasing the electron excitation energy and therefore improving the photocatalytic performance from the increasing the sensitivity under visible light irradiation.in this project CoPCTS , Mordant dye and N3(Ruthenium 535) used as dye-sensitizers. Also The addition of VIII group metals on TiO2 is improving the photocatalytic activity that increasing the photocatalytic reaction rate because of the intermediation role of them for moving the conduction band electrons to electron acceptors and increasing the pair electron-holes long-life that in this case Pt loading used as a VIII group metal. In this project Titanium Isopropoxide as a precursore and... 

In recent years, mesoporous nanocrystalline TiO2 films have been regarded extensively. This kind of materials due to having unique surface area, structural and bulk properties, is used in many technological applications. In this work, a stable TiO2 sol was prepared using F127 Copolymer template and evaporation induced self-assembly method (EISA). The mesoporous TiO2 powders and thin films were then prepared. The as-deposited thin films were aged under five different conditions for 72h. Finally the samples were heat treated at 350°C, 400°C and 450°C. N2 adsorption/desorption results verified formation of mesoporous structure. Moreover, x-Ray diffraction patterns exhibited that the synthesized... 

In this project, the nanostructured titanium oxide with heaily doping of oxides of cerium and tin was synthesized using the sol-gel process and its properties were studied. To synthesize TiO2, titanium tetraisopropoxide precursor was used. Cerium nitrate and aqueous tin chloride precursors were utilized for cerium and tin synthesis. Then, they were mixed with Titania precursor causing a severe doping. After that, a gel was produced and it was aged and eventually, it was dried and calcined. XRD and SEM were used to determine the phase and particle size SEM and XRD results showed that doping had great impact on TiO2 crystals. The approximate size of nanoparticles was calculated using... 

Ionization probability of Cl2 molecule is studied by irradiation of 800 nm Ti: Sapphire laser pulses at intensities of 1014 Wcm-2 to 1016 Wcm-2 with the Gaussian package. Molecular orbital symmetry and orientation of the molecule dipole moment with laser field polarization axis are very effective in ionization probability. The results show that the most ionization probability for the intensity of 1014 wcm-2 is at 900 and also 50 at intensity of 1016 wcm-2. Due to the lack of intrinsic dipole moment, variation of dipole moment with the intensity, bond length and time evolution of dipole moment are investigated. It is found that there is a linear dependance of these parameters with ionization... 

This research tries to simulate the conditions of nanosized TiO2 powder production from pure commercial precursors, to produce nanosized TiO2 powder by leaching kahnouj ilmenite concentrate. For this purpose, the ilmenite concentrate was first oxidized to study the kinetics and optimization of oxidation process before leaching. Then the effect of pre-oxidation on the iron and titanium leaching efficiency was studied. Then the reductive leaching of concentrate using zinc and iron powders as reducing agent for Fe (III) to Fe (II) reaction was studied. The effect of reducing agent as well as oxidation and reduction on the leaching efficiency was studied. At the next step the optimum conditions... 

The conversion of CO2 gas into value-add chemicals known as solar fuel technology attracted much consideration from the beginning of the 21st century owing to the potential of this technology in solving the climate change and energy shortage issues. In the present study, a well-known photocatalyst, TiO2, was doped with Bismuth element and was subjected to Pt nanoparticles loading as a cocatalyst to boost the photocatalytic CO2 conversion. Pristine TiO2 and Bi-doped samples were prepared by sol gel method. Then, a facile photo-deposition method was employed to introduce Pt onto the surface of TiO2. Various characterization techniques including XRD, DRS, BET, PL, FTIR, FESEM and TEM, were used...