Sharif Digital Repository

In this research we focus on synthesis and analysis of metal and metal oxide nanoparticles and their photocatalytic activity. At the beginning a high current DC power supply and a reactor for the electrical arc discharge process designed and implemented. Several nanoparticles such as tungsten oxide, zinc oxide, silver and gold have synthesized by this method in deionized water, deionized water including surfactants and stabilizers and analyzed. Several characterization techniques such as X-ray diffraction (XRD), dynamic light scattering (DLS) X-ray photoelectron spectroscopy (XPS), BET, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-Vis spectroscopy have... 

The aim of this project is investigation on synthesis and characterization of the TiO2-CNT nanocomposite films on aluminum substrate by sol-gel dip coating method. The pure TiO2 and TiO2-CNT nanocomposite layers were coated on aluminum substrate and heat treated in 400 C. In this work Ti-tetra isopropxide and different amounts of CNTs (5,10,15 %wt), were used for obtain the composites. The coatings were characterized by X-Ray diffraction (XRD) and the crystallite size of TiO2 was calculated by Scherrer formula. The corrosion properties of coating were examined by polarization test, and corrosion resistance of pure TiO2 was compared with TiO2-CNT coatings, and It showed that the composite... 

TiO2, Ag/TiO2 and AgBr/TiO2 synthesized by sol – gel method. Synthesized samples were characterized by X- Ray diffraction (XRD) , Fourier transformed infrared ( FT – IR) , Scanning electron microscopy ( SEM) techniques. The results of XRD showed that the particle size is in the nanorange and anatase form of titania is present in all of the photocatalysts. Kinetics of photocatalytic degradation of an azo dye (Acid Orange 7) on photocatalysts was studied. The effect of various parameters such as dye concentration, amount of photocatalyst( AgBr/TiO2) and pH of solution on the rate and efficiency of degradation of Acid Orange 7 was studied. The optimized conditions ( [AgBr/TiO2]= 100 ppm,... 

The present work is based on the, synthesis and investigation of photocatalytic activity of TiO2, TiO2/MWCNT, ZnO and ZnO/MWCNT nanostructures. The nanostructures were prepared using multi-walled carbonnanotubes (MWCNT) as templates.The SEM images of TiO2 and ZnO nanoparticles and TiO2/MWCNT andZnO/MWCNT showed that nanosize TiO2 and ZnO particles homogeneously and densely supported on the surfaces of multiwall carbon nanotubes the photocatalytic activity of the TiO2, TiO2 /MWCNT, ZnO and ZnO/MWCNT was examined by the degradation of Basic Blue 41(BB41) under UV and Vis lights. The optimum conditions for degradation of BB41 on TiO2 where found to be: calcination temperature (450 °C), dye... 

Titania is one of the photocatalytic materials , but low quantum yield and relatively high band gap of TiO2 limited its applications.There are several ways to improve the photocatalytic properties of this material relied on narrowing the band gap,by doping TiO2 with other metals and oxides or increasing its specific surface area.In this work ,TiO2-SiO2-Ni coating have been made by sol-gel process and deposited on quartz substrate by using of dip-coating method .Effect of increasing Nickel content in nanocomposite and primary sol on crystalline structure,morphol ogy, photocatalytic properties and specific surface area have been investigated by means of X-Ray diffraction method, FT-IR, SEM,... 

Improvement of semiconductors photocatalytic activity by different means has always been one of the challenges for researchers. Semiconductors doping for band-gap engineering and changing morphology to increase specific surface area and photocatalytic reaction sites are amongst these efforts. In this research simultaneous effect of these two parameters for three morphologies containing nanoparticle, nanowire and micro dandelion, simultaneously doped with carbon and nitrogen has been investigated. Final purpose of this thesis is to decrease the band-gap energy close to soft UV photon energies to make surface photodynamic therapy possible. Nanoparticle morphology with size distribution between... 

Since previous models can not give a complete description for electrospinning electrical instability, using polymer solutions with diifferent properties, the aim of the existing thesis is to propose a new model that covers a range of materials from non-conducting to conducting and from viscous to elastic and also the initial jet’s tension. In addition, since the previous models have used large wave length approxiamtions, using accurate calculations we showed that the new model has better results for small wavelengths of about two times the jet’s radii. To compare the model to experimental results, we designed and made a proper setup to record the electrospinning process for a PEO solution... 

Azo dyes that are the most common dyes in textile industries, are toxic and stable complex compounds. Release of this dyes in environment disturb the ecosystem and endanger human health. So selection of an appropriate method for treatment of them is a sensitive work. photocatalytic degradation is one of the best promising methods because of its perfect mineralization, middle condition and lack of creating the secondary pollutant. In this research CuO/CNT nanocomposite was synthesized and used as a photocatalyst. The surface features of CuO/CNT were surveyed by using Fourier transform infrared(FTIR), X-ray diffraction (XRD) and Scanning electron microscopy (SEM). Photocatalytic efficiency of... 

Enhancement of photocatalytic characteristics of semiconductors have been always a challenge for the researchers. Doping semiconductors for adjusting their energy gap and changing their morphology in order to increase their effective surface area and reaction sites are examples of their endeavor to overcome the challenge. In this research, nanostructured Aluminum Titanate powder was synthesized with Sol-Gel process and by altering synthesis parameters, the best synthesis condition to get the best possible band gap was discovered. Moreover, we examined the photocatalytic properties of the recently developed material “tialite”, which were not studied before and also evaluated the effect... 

The main purpose of this research was functionalizing graphene, in order to achieve higher hydrophobicity, and producing nanocomposite of functionalized graphene and titanium dioxide by hydrothermal method, and sequently invastigation on photocatalytic properties of the powders and corrosion properties of EPD coated samples. Graphene oxide was synthesized by improved Hummers method and reduced and sequently was functionalized through the chemical process with hydrazine and octadecylamine respectively. Then the nanocomposite of functionalized graphene-titania was synthesized by use of titanium isopropoxide precursor and its photocatalytic properties were measured. The analysis of the... 

In this thesis, graphene/titanium oxide and graphene/tungsten oxide composites were synthesized using arc discharge in liquid and their photocatalytic behavior was studied. Based on physical principles of the arc discharge in liquid, geometry of point-point was used for metallic Ti and W electrodes. TiO2 and WO3 nanoparticles and their nanocomposites with graphene and graphene oxide (GO) were studies using DLS, UV-vis, PL, ICP, FTIR, XRD, Raman and TEM characterization. The concentration of aqueous solution of Rhodamine B mixed with graphene/WO3 and GO/WO3 composites and WO3 nanoparticles under ultraviolet light was measured versus time and reached to 0.1, 0.6 and 0.6 of the initial value... 

Because of limitation of titania coating that can act as self-cleaning surface under UV light irradiation, introduction of transition metal ions into titania lattice can decrease band gap energy of titania in order to activate the coating under visible light irradiation. In this research, by using vanadium element and silica prelayer, a titania coating was deposited on the soda-lime glass substarte to produce self-cleaning surface. The scope of coating was to increase the photocatalytic activity and hydrophilicity of vanadium doped titania coating on the soda-lime glass and silica coated glass by sol-gel dip coating method. XRD and FTIR analysis were done on the powders with different... 

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.... 

Modified zeolitic nanostructures were prepared by sol-gel, hydrothermal and coprecipitation methods. At first step, natural zeolite was used as a support for preparing the Ag/AgBr/TiO2 photocatalysts. Their photocatalytic properties were studied by degradation of pollutants and microorganism inactivation at the presence of different illumination source. These processes were mechanistically investigated and the results were explained. At second step, mordenite anocrystals, which synthesized by hydrothermal method, were used as an effective support to prepare the AgX/TiO2/MOR photocatalysts. Photocatalytic degradation of an azo dye performed over these nanocomposites and a mechanism suggested... 

The aim of conducting this research is to study, fabrication and photocatalytic application of electrospun ZnO-based composite nanofibers. One of the most important challenges is to apply photocatalyst under solar irradiation and improve its activity for pollutant degradation. ZnO is a wide band gap semiconductor, hence, it is not active under the visible light. In Iran, we have at least 300 sunny days in a year. Therefore, fabrication and application of photocatalytic material with activity under the sunlight which contains 47% of visible light is so vital in our country. Since CuO is a visible light active photocatalyst and its interface with ZnO forms a type I heterojunction, this... 

Environmental issues and lack of drinking water had forced researchers to find some alternatives in order to wastewater treatment. Since dyes are used in a variety of industrial application such as textile, pharmaceutical, etc.; therefore, wastewater of these factories makes several environmental problems. Using catalysis under UV- irradiation (photocatalysis) is one of the cases that is used in wastewater treatment which the catalyst stimulated under UV- irradiation and this process degraded dyes. In this work, reactive red 198 degradation is investigated with MIL-53(Fe) and MIL-100(Fe) and in the literature section, the methods that was implemented by other researchers is studied.... 

Removing pollutants of water and, in general, wastewater treatment is one of the most important issues in the world. In this research, we synthesized a nanophotocatalyst based on znic-iron in the form of a magnetic core-shell Fe3O4@ZIF-8, and used to degrade the malachite green toxic color of wastewater. SEM, XRD and FT-IR analyzes have been taken and analyzed fore all three core, shell and core-shell composite catalysts.Due to the band gap of core-shell nanocomposite and the performance of the malachite green dye, a photocatalytic process under the visible light was obtained, which at an optimum amount of photocatalyst 0.003g, we reach 99.2% dye degradation at the 30ppm concentration. This... 

Due to the increasing number of Advanced Oxidation Processes (AOPs) that are exploited to eliminate emerging and recalcitrant contaminants from water supplies, photocatalytic degradation of Reactive Blue 21 dye using Zinc Oxide nanoparticles is investigated in both a slurry phase and an immobilized photoreactor. The structural and optical properties of the prepared ZnO nanoparticles were examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and UV-Visible Diffuse Reflectance Spectroscopy (UV-vis DRS). The effects of photocatalyst concentration, calcination temperature, pH and UV lamps were optimized in the slurry phase photoreactor. It was shown that 250 ppm of ZnO that was... 

In the first section, due to the important role of nanocatalysts in different fields of chemistry, magnetic metal ferrite nanoparticles were synthesized. Nickel ferrite and cobalt ferrite magnetic nanoparticles were synthesized using co-precipitation method and were characterized. Then, these nanoparticles which have been crystalized in spinel structure were employed to catalyzed different C-C and C-heteroatom bond formation reactions through C-X bond activaion. In all cases, the proposed catalytic systems could catalyze the reactions efficiently and the optimized reaction conditions were milder and more effective than the previous reported methods. In the next section, C-halogen bond... 

In this projekt, nanophotocatalysts containing metal oxides and oxy-acids based on the nanoporous materials were synthesized. The photocatalytic properties of the prepared samples were evaluated by the photodegradation of day moleculs in photocatalytic systems. The catalytic results revealed that Ag3VO4/Cu-MOF/rGO exhibits noticeably an improvement in both efficiency and rate of AB92 photodegradation in comparison with the pure Ag3VO4. Using different scanning mechanisms for the catalytic properties of the synthesized nanocomposites, it was clearly demonstrated that the anionic superoxide plays a decisive role. Reduction of 4-NP in the presence of NaBH4 was also used to investigate...