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titanium
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Photocatalytic degradation of furfural by titania nanoparticles in a floating-bed photoreactor
, Article Chemical Engineering Journal ; Volume 146, Issue 1 , 2009 , Pages 79-85 ; 13858947 (ISSN) ; Vossoughi, M ; Borghei, M ; Sharif University of Technology
2009
Abstract
In this research, an attempt was made to investigate the potential of nanophotocatalysts for treatment of hazardous wastewater streams. Titanium dioxide nanoparticles (as photocatalyst) were immobilized on a porous and low-density support called "perlite" using a very simple and inexpensive method. TiO2-coated perlite granules were used in a "Floating-bed photoreactor" to study the photocatalytic purification process of a typical wastewater polluted by furfural. The effects of initial concentration, catalyst mass/solution volume ratio, oxidant molar flow, residence time, and light intensity on process removal efficiency, and kinetics of the reactions were studied. SEM analyses showed a...
Effect of Titanium Compounds on H-kinetics of Nanostructured Magnesium Hydride
, M.Sc. Thesis Sharif University of Technology ; Simchi, Abdolreza (Supervisor) ; Maddah Hosseini, Hamid Reza (Supervisor)
Abstract
Magnesium hydride (MgH2) is an attractive candidate for solid-state hydrogen storage applications. Scanning Electron Microscopy observations showed that during cyclic absorption and desorption considerable micro-crack was formed at the reaction interface and reduced the nucleation time. To improve the kinetic properties of MgH2 during dehydrogenation a nanostructured MgH2-10%mol TiH2-6%mol TiO2 material system was prepared by high-energy ball milling. Isothermal analysis with commercial volumetric sievert demonstrated that the addition of titanium compounds significantly improved the kinetics of dehydrogenation compared to commercial MgH2
Fabrication of TiO2 Dye-sensitized Solar Cells with Different Morphologies and Phase Compositions of Scattering Layer
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Mohammad Reza (Supervisor)
Abstract
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...
Study of UV Radiation Effects on Fischer–Tropsch Synthesis
, M.Sc. Thesis Sharif University of Technology ; Sadighi Bonabi, Rasoul (Supervisor)
Abstract
Recently, The interest of using the coherent and incoherent photons in chemical synthesis have been raised considerably. In this project, theoretical calculations due to investigation of irradiation’s effects on Fischer- Tropsch synthesis have done. Fischer – Tropsch synthesis is the process that converts synthesis gas, i.e. a mixture of carbon monoxide and hydrogen, in to a wide range of long chain hydrocarbons and oxygenates. We invest the first chapter of this project to introduce of Fischer- Tropsch synthesis and its importance. Following in the next chapter we have analyzed the photocatalyst in microscopic scale. In third chapter, we have claimed the necessary theories which are useful...
Surface Modification of Metallic Implants and Improvement of their Biological Properties in Presence of Bioactive Ceramic Nanoparticles
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhad, Khatiboleslam (Supervisor)
Abstract
By consideration of increasing demands to use implants and efforts to get technical knowledge and localization of this implants, considerable research in this field is needed. Therefore, presentation of a coating which is able to provide parameters needed for an acceptable implant is the aim of this study. In this direction, modification of surface of metallic implants in order to achieve nanotubes of titanium oxide, with the purpose of providing biocompatibility was done. On the other hand, because chronic infection of the implant’s surrounding is one of the main important reasons in rejection of implants, 〖TiO〗_2 nanotubes as a drug carrier were used in order to solve this problem. So,...
Enhanced Electronic Properties in Mesoporous TiO2 Via Passivation Treatment in Perovskite Solar Cells
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Mohammad Reza (Supervisor)
Abstract
Perovskite solar cells are the new generation of solar cells, and are mainly introduced in two types of structures.1) planer and 2) mesoscopic structure. The difference between these two structures derives from the absence of mesoporous layer in the planer structures. The mesoporous layer acts as an electron transporting layer, and is mainly a titanium dioxide semiconductor. To apply the mesoporous layer, the preparation of the TiO2 paste is needed.The synthesis of titanium dioxide nanopowder for the preparation of TiO2 paste requires high temperature heat treatment and is not desirable in terms of energy consumption.Another weakness of this layer is the presence of surface defects, which...
TiO2 Production by Acid Leaching of Upgraded Titanium Slag
, M.Sc. Thesis Sharif University of Technology ; Askari, Masoud (Supervisor)
Abstract
In Iran, titanium dioxide is still not produced and imports of titanium dioxide are required by various industries, including dyeing, electrodeposition, plastics and Therefore, according to the Ministry of Industries and Mines objectives, to obtain the technology of extraction Ti and TiO2, a research was carried out on titanomagnetite concentrate, extracted from the minerals of the plancher titanumitent and low-grade kahnoj. In this research, titanium dioxide is produced by sulfate method. Solid state recovery and magnetic separation were used to isolate titanium and iron. The dissolution process was then performed to achieve maximum dissolution. At this stage, the effects of temperature,...
Synthesis of Nanocomposites based on Carbon nanotubes and Graphene/Ionic Liquid for Construction of Biosensors
, Ph.D. Dissertation Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor) ; Ghourchian, Hedayatollah (Co-Advisor)
Abstract
In this project during 2 sections the synthesis and application of nanomaterials based on carbon nanotubes and graphene oxide for immobilization of Glucose oxide and Horseradish peroxidase enzymes for construction of effective biosensors were investigated. In section 1, we introduce a new nanomaterial in which TiO2-coated carbon nanotubes were functionalized with amine groups (NH2-TiO2-CNTs). This nanomaterial was fixed on a glassy carbon electrode surface and then its ability for direct electron transfer of Glucose oxidase (GOx) and Horseradish peroxidase (HRP) on the modified electrode was investigated. The direct electrochemistry of immobilized GOx and its electron transfer parameters at...
Preparation of New Titanium Nitride-Carbon Nanocomposites and Evaluation of their Electrocatalytic Behavior
, Ph.D. Dissertation Sharif University of Technology ; Ghorbani, Mohammad (Supervisor) ; Dolati, Abolghasem (Supervisor)
Abstract
Titanium nitride-carbon nanocomposites are synthesized by the reaction of TiCl4 and NaN3 in supercritical benzene medium that also serves as a carbon source. In order to improve the crystallinity of the as-prepared precursor (SI), it is further heat-treated at 1000 ˚C for 3-10 h using anhydrous ammonia and UHP nitrogen atmospheres at 1000 ˚C (SIII-SV). Moreover, to improve electrochemical behavior, the synthesized nanocomposite (SIV) is modified with Pt nanoparticles using a polyol process. For better understanding of synthesized catalyst nature and justifying their variant ORR activity several analyses are done. X-ray diffraction (XRD), Raman spectrum, field emission scanning electron...
Optical and Electrical Properties of Nanostructures Prepared by Hydrothermal Method for Application in Nanostructured Solar Cell Electrode
, M.Sc. Thesis Sharif University of Technology ; Iraji Zad, Azam (Supervisor)
Abstract
In this research we focus on study and fabrication of one dimentianal TiO2 nanostructures and nanoheterostructures on TiO2 nanofibers in order to use them in Dye Sensitized Solar Cells (DSC). Nanofibers of titanium oxide have been fabricated using hydrothermal method. Then, hierarchical TiO2 nanostructures were grown on the nanofibers via another hydrothermal step. Increasing the effective surface of nanofibers, we achieved two secondary architectures from fibers:1-Nanoparticular fibers (TiO2 nanoparticles grown on nanofibers).2-Nanostars.After fabrication, the SEM and XRD characterizations were provided. Furthermore, the suitable pastes of these nanostructures were prepared for application...
PEC Sensing of Glucose Using one Dimensional TiO2 Nanostructure Modified by Two Dimensional Material
, M.Sc. Thesis Sharif University of Technology ; Naseri, Naimeh (Supervisor)
Abstract
In this study, one dimensional titanium dioxide nanostructures including nanotube and nanowire were synthesized by anodization and hydrothermal methods respectively and were used for PEC glucose sensing. Meanwhile various length of nanotubes was investigated toward glucose sensing. Finally, nanotubes with the length of 2.7 µm were selected as the optimum sample. Finally, to improve sensitivity toward glucose, TiO2 nanotubes were modified by graphene oxide nanosheets which caused several percent increase in PEC sensing performances. In the next stage branched TiO2 nanowires were grew on FTO substrate in various conditions. In spite of acceptable reproducibility of this structure,...
Electrophoretic Deposition of TiO2 Nanoparticles and Fiber for DSC Application
, M.Sc. Thesis Sharif University of Technology ; Taghavinia, Nima (Supervisor)
Abstract
Dye Sensitized Solar cell (DSC) is the third class of solar cell, which consists of a nanocrystalline, mesoporous of semiconductor(The best one is Tio2), covered with a monolayer of dye molecules, platinum coated on FTO as a counter electrode and a redox electrolyte. This Photovoltaic cell which is promising low-cost materials, works on electron separation of dye molecule, and electron injection to semiconductor’s conduction photo- electrode structure and its porosity is affected the DSC’s performance. Recently, use of electrophoretic deposition (EPD) for TiO2 electrode (which best found for photo-electrode in DSC) fabrication has gained increased interests. In this method charged particles...
Repeatability of Lithium Adsorption and Desorption on TiO2 Nanotubes from Brines
, M.Sc. Thesis Sharif University of Technology ; Askari, Masoud (Supervisor)
Abstract
Today, recycling lithium as a valuable metal from brine plays an important role in various applications such as battery manufacturing, computers, aerospace and automobiles. Among the aqueous methods available for the extraction of the lithium element in brines, ion exchange by TiO2 nanosorbents is one of the most efficient methods. In this study, first the titanium dioxide nanotubes were well synthesized by anodizing method and the nanograss created after the anodizing process were completely eliminated. Then, the effect of three cathodes of aluminum, graphite and stainless steel in order to select the best cathode and achieve a regular morphology as well as their replacement with platinum...
Charactrization of Oxidized Alginate- Gelatin Composite Hydrogel Reinforcement by Ti3C2Tx Mxene for Utilization in Biomedical Applications
, M.Sc. Thesis Sharif University of Technology ; Nemati, Ali (Supervisor) ; Mashayekhan, Shohreh (Co-Supervisor)
Abstract
Tissue engineering is a science that tries to create new tissues by using cells, growth factors and appropriate biological materials in order to repair damaged organs and replace parts lost due to various reasons. In this research, the effect of adding mxene sheets on the oxidized alginate-gelatin hydrogel scaffold was investigated. For this purpose, mxene nanosheets were first synthesized by Max phase chemical etching and its synthesis was confirmed by X-ray diffraction spectroscoy, field emission scanning electron microscope, X-ray energy diffraction spectroscopy, Fourier-transform infrared spectroscopy, UV-visible spectroscopy. Then, in order to prepare the scaffolds, different amounts of...
Effect of Interlayer Prepared by Plasma Electrolytic Oxidation in Joint of Ti6Al4V and Al6061-t6 by Friction Stir Welding
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
Connecting titanium and aluminum alloys is widely used in different industries such as transportation, chemical, aircraft manufacturing, etc. Friction stir welding is one of the methods of joining these two metals. In order to obtain a sound joint, the formation of intermetallic phases in the interface must be controlled. One of the ways to control these phases is the use of an interlayer, which in this research is the interlayer applied by plasma electrolytic oxidation method with different current densities and coating times. In this regards, first the optimal parameters of friction stir welding were determined. Then, Ti6Al4V and Al6061-t6 welding was performed in the presence of...
Simply synthesized TiO2 nanorods as an effective scattering layer for quantum dot sensitized solar cells
, Article Chinese Physics B ; Vol. 23, issue. 4 , 2014 ; Zad, A. I ; Molaei, M ; Sharif University of Technology
Abstract
TiO2 nanorod layers are synthesized by simple chemical oxidation of Ti substrates. Diffuse reflectance spectroscopy measurements show effective light scattering properties originating from nanorods with length scales on the order of one micron. The films are sensitized with CdSe quantum dots (QDs) by successive ionic layer adsorption and reaction (SILAR) and integrated as a photoanode in quantum dot sensitized solar cells (QDSCs). Incorporating nanorods in photoanode structures provided 4- to 8-fold enhancement in light scattering, which leads to a high power conversion efficiency, 3.03% (Voc = 497 mV, Jsc = 11.32 mA/cm2, FF = 0.54), in optimized structures. High efficiency can be obtained...
Study plasma electrolytic oxidation process and characterization of coatings formed in an alumina nanoparticle suspension
, Article Vacuum ; Vol. 108, issue , 2014 , p. 12-19 ; Faghihi Sani, M. A ; Mohammadi, M. R ; Sharif University of Technology
Abstract
Alumina-silicate composite coatings were formed on titanium substrate by plasma electrolytic oxidation (PEO) process using a silicate-based electrolyte containing alumina nanoparticles. Microstructure, chemical and phase compositions, and thickness of the coatings were investigated to determine, coating mechanism and probable reactions during the process. The effect of processing time on corrosion resistance of the coatings was investigated using the potentiodynamic polarization test. Barrier layer (TiO2) formation, micro arcs occurrence, and electrolyte ionization were the main stages of PEO coating growth process. Alumina nanoparticles were incorporated into the coating by cataphoretic and...
Single and double stage sintering of mechanically alloyed powder for nanostructured Ti6Al4V foams usable in cancellous scaffolds
, Article International Heat Treatment and Surface Engineering ; Volume 7, Issue 1 , 2013 , Pages 43-48 ; 17495148 (ISSN) ; Aryana, M ; Hassanzadeh Nemati, N ; Alizadeh, M ; Ebadifar, A ; Sharif University of Technology
2013
Abstract
Mechanical alloying and sintering were used to fabricate nanostructured Ti6Al4V scaffolds of highly controllable pore geometry and fully interconnected porous network. Elemental powders were milled for different periods of time (10, 20, 30, 40 and 60 h), mixed with 40-60 vol.-% of 200-400 μm cuboidal NaCl, compacted at 500-600 MPa and sintered according to single or double stage heat treatment regimes at 790 and 950°C under vacuum. After sintering, the samples were soaked in distilled water to washout the NaCl. Foamy microstructures were obtained showing well shaped biopores and fragmentary embedded micropores. The shape of initial NaCl was copied into the biopores which had highly...
Effects of thickness and texture on mechanical properties anisotropy of commercially pure titanium thin sheets
, Article Materials and Design ; Volume 44 , February , 2013 , Pages 528-534 ; 02641275 (ISSN) ; Ekrami, A ; Ziaei Moayyed, A. A ; Sharif University of Technology
2013
Abstract
Simultaneous effects of thickness and texture on the anisotropy of mechanical properties and fracture behaviors of commercially pure titanium thin sheets were studied. The activation of different deformation systems, due to the split distribution of basal texture, led to mechanical properties anisotropy. The crack initiation and propagation energies, when the loading direction was parallel to the initial rolling direction, decreased with increasing thickness ranges from 0.25 to 1 mm. The changes of size, shape and distribution of dimples with increasing thickness confirmed the restriction of deformation systems and the development of triaxial stress state and plane-strain condition at the...
Micro arc oxidation of nano-crystalline Ag-doped TiO2 semiconductors
, Article Materials Letters ; Volume 65, Issue 5 , March , 2011 , Pages 840-842 ; 0167577X (ISSN) ; Aminzare, M ; Molaei, R ; Sadrnezhaad, S. K ; Sharif University of Technology
2011
Abstract
Simple synthesis of silver doped TiO2 nanostructured layers by micro arc oxidation process is reported for the first time. The layers consisted of anatase and rutile phases whose characteristic XRD-peaks shifted toward lower diffraction angles when compared to the pure micro arc oxidized TiO 2 layers. Silver-doping was confirmed by XPS technique. The anatase phase crystalline size was determined as 27.6 and 21.8 nm for the layers grown under the voltages of 350 and 500 V. Employing a UV-Vis spectrophotometer, a red shift in the absorption edge of the layers was observed when silver was incorporated into the titania lattice