Loading...
Search for:
zinc-oxide
0.008 seconds
Total 192 records
Fabrication and Characterization of ZnO Composites Nanofibers by Electrospinning Method for Photocatalytic Application
, Ph.D. Dissertation Sharif University of Technology ; Moshfegh, Ali Reza (Supervisor) ; Pourjavadi, Ali (Co-Advisor)
Abstract
In this research we focus on study and fabrication of ZnO composite nanofibers by electrospinning method for photocatalytic application. The most important challenges in the field of photocatalyst are photocatalytic activity under the visible light and efficiency enhancement. ZnO is a wide band gap semiconductor and it is not active under the visible light. In Iran, we have more than 300 sunny days in a year. Therefore fabrication and application of photocatalytic material with activity under the sun light that contained 40% of visible light is so vital in our country. In the first part of this project, ZnO-CNT nanofibers were fabricated and carbon doped in the crystal lattice of the ZnO....
An Investigation on Aging of Rubber Compounds Against Acidic Gases
, M.Sc. Thesis Sharif University of Technology ; Mousavi, Abbas (Supervisor) ; Shojaei, Akbar (Supervisor)
Abstract
Aging of rubber compounds at high temperature and pressure acidic gas is a challenge for using them for a long time. Therefore, in this thesis aging of NBR/PVC compounds against H¬2S and CO2 has been investigated. The main method have been used is Full Factorial Design of Experiment. The parameters have been examined are content of zinc oxide, plasticizer RPO ASTM 290 and antioxidant 4010 NA. The content have been set in tow levels and effect of each have investigated in ambient and 120 degree of centigrad temperature. The results show that the effect of antioxidant 4010 NA on aging of compounds is negative and zinc oxide and plasticizer RPO ASTM 290 are positive
Study of ZnO Nanoparticles for the Photocatalytic Degradation of a Organic Pollutant
, M.Sc. Thesis Sharif University of Technology ; Baghalha, Morteza (Supervisor) ; Ahmadpour, Ali ($item.subfieldsMap.e) ; Khorashe, Farhad ($item.subfieldsMap.e)
Abstract
due to high mineralization rate of Zinc oxide، chemical and physical stability, non-toxicity and low price as the most promising photocatalysts studied, although its use is not too satisfactory. Because of the wide energy gap(3.2 ev) and for photocatalytic activity needs to UV light Unfortunately, the solar spectrum is made up only 5-7% of UV light, while 46-47% is the spectrum of visible light and infrared. Doped zinc oxide nanoparticles with metal and non-metallic atoms could increase the photocatalytic properties under visible light irradiation. In this research, nanoparticles of zinc oxide was doped by fluorine as Dopant. The results showed that photocatalytic activity of the modified...
photocatalytic elimination of organic pollutant including dye and Pharmaceutical materials in batch reactor using Hierarchical ZSM-5
, M.Sc. Thesis Sharif University of Technology ; Kazemeini, Mohammad (Supervisor) ; Hosseinpour, Vahid (Co-Supervisor)
Abstract
The aim of this research is to make a hierarchical zeolite catalyst as a basis for photocatalytic removal reactions of organic pollutants including dyes and drugs. The three main parts of this thesis deal with preparing the photocatalyst, performing the characterization test and investigating the reaction in different operating conditions. To prepare zeolite, first an organic molecule was synthesized to increase the diameter of the holes and it was used along with the rest of the precursors in the hydrothermal method. To increase the efficiency of photocatalytic reactions, the silver element was deposited on the ZnO / zeolite catalyst by photodeposition method and its characteristics were...
Kinetics and Mechanism of the Reduction of Hexavalent Chromium to Less Toxic Materials on ZnO Nanostructured Surfaces: the Effect of Wavelength and Light Intensity on the Reaction Rate
, M.Sc. Thesis Sharif University of Technology ; Moshfegh, Alireza (Supervisor) ; Naseri, Ameneh (Supervisor)
Abstract
Hexavalent chromium ion (Cr+6) is a very toxic type of heavy metal in industrial effluents which is not biodegradable and accumulates in the human body that can cause genetic mutations and cancer. The aim of this project is to investigate the effect of wavelength and intensity of appropriate light on the reaction rate of photocatalytic reduction of Cr+6 ion to less toxic materials. In this project, we first designed and constructed a photocatalytic reactor to investigate the effect of wavelength and intensity of incident light on the reaction rate. The home-made photocatalytic reactor consisted of 120 LEDs in 12 different wavelengths, which has ability to control the intensity and...
Convenient synthesis of chlorohydrins from epoxides using zinc oxide: Application to 5,6-epoxysitosterol
, Article Heteroatom Chemistry ; Volume 20, Issue 3 , 2009 , Pages 157-163 ; 10427163 (ISSN) ; Saeidian, H ; Mirjafary, Z ; Jebeli Javan, M ; Moridi Farimani, M ; Seirafi, M ; Sharif University of Technology
2009
Abstract
Efficient synthesis of protected and unprotected chlorohydrins has been achieved by ring opening of epoxides with acetyl/benzoyl chloride and TMSCl using a catalytic amount of ZnO as a reusable catalyst. The applicability of ZnO is further extended by performing the cleavage of the natural product 5,6-epoxysitosterol with acetyl chloride. © 2009 Wiley Periodicals, Inc
Synthesis of tetrahydrofuran from maleic anhydride on Cu-ZnO-ZrO2/H-Y bifunctional catalysts
, Article Catalysis Communications ; Volume 9, Issue 13 , 2008 , Pages 2195-2200 ; 15667367 (ISSN) ; Soltanieh, M ; Kazemeini, M ; Khandan, N ; Sharif University of Technology
2008
Abstract
A series of bifunctional Cu-ZnO-ZrO2/H-Y catalysts of different compositions were prepared by coprecipitating sedimentation method and were characterized by surface area and XRD analyses. The catalytic performance in synthesis of tetrahydrofuran was evaluated and optimized in a three-phase slurry batch reactor. The experimental results showed that the appropriate ratio of Cu/ZnO in the hydrogenation catalyst was 50/45, for which the conversion of maleic anhydride (MA) and selectivity of tetrahydrofuran (THF) reached 100% and 46%, respectively, at 50 bar and 493 K after 6 h of operation. Also, according to these results, it was demonstrated that the incorporation of zirconium oxide in the...
SnO2/ZnO double layer thin films: A novel economical preparation and investigation of sensitivity and stability of double layer gas sensors
, Article International Journal of Nanomanufacturing ; Volume 2, Issue 1-2 , 2008 , Pages 59-69 ; 17469392 (ISSN) ; Shokuhfar, A ; Sadrnezhaad, S. K ; Shokuhfar, T ; Sharif University of Technology
Inderscience Publishers
2008
Abstract
A double-layer SnO2/ZnO gas sensor was produced by utilisation of SnOSUB align=right2 and ZnO thin films. Top layer consisted of SnOSUB align=right2 produced by a sol gel-controlled annealing technique. Bottom coating consisted of ZnO thin film precipitated by Two-Stage Chemical Deposition (TSCD) from an aqueous zinc-containing solution. Both top and bottom coatings were analysed by SEM, XRD, EDAX and AAS. Gas sensitivity of the SnO2/ZnO double layer was determined by electrical resistance measurements. Although sensitivity was slightly reduced by double-layer formation, selectivity and stability were considerably improved by combination of the two thin layers. The existence of an...
Effects of substrate material and annealing temperature on morphology of zinc oxide films
, Article Materials Science and Technology ; Volume 22, Issue 3 , 2006 , Pages 308-314 ; 02670836 (ISSN) ; Sadrnezhaad, S. K ; Sharif University of Technology
2006
Abstract
A two stage chemical deposition (TSCD) technique is used to produce ZnO films on quartz glass (QG), soda lime glass (SLG) and high purity alumina (HPA) from an aqueous solution of zinc complex. The effects of the substrate material on the chemical composition and morphology of the deposited layer are investigated. The effects of different annealing temperatures (180, 300, 500 and 800°C) on the morphology and orientation of the ZnO crystallites are also determined. X-ray diffraction diffractograms show that above 300°C, the intensity of (002) peak considerably decreases with increasing temperature. Results indicate that changing the substrate from QG to SLG does not significantly influence...
Evaluation of efficiency in zinc recovery from waste materials
, Article 2006 TMS Fall Extraction and Processing Division: Sohn International Symposium, San Diego, CA, 27 August 2006 through 31 August 2006 ; Volume 1 , 2006 , Pages 445-452 ; 0873396332 (ISBN); 9780873396332 (ISBN) ; Halali, M ; Sharif University of Technology
2006
Abstract
In this report, the efficacy of different factors such as temperature of reaction, time of reaction and depth of bed are investigated in a process of recovery of zinc oxide from zinc ore concentration residues in a fluidized bed furnace. Under optimum conditions, there was more than 93.5% zinc oxide in products
Design & Synthesis of ZnO-based Composite Nanofiber Photocatalysts with Z-Scheme Structure for Degradation of Organic Pollutants
, Ph.D. Dissertation Sharif University of Technology ; Moshfegh, Alireza (Supervisor) ; Pourjavadi, Ali (Supervisor) ; Mahmoodi, Niaz Mohammad (Co-Supervisor)
Abstract
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...
Effects of initial precursor and microwave irradiation on step-by-step synthesis of zinc oxide nano-architectures
, Article Materials Letters ; Volume 67, Issue 1 , 2012 , Pages 342-345 ; 0167577X (ISSN) ; Samberg, J. P ; Ghorbani, H ; Kajbafvala, E ; Sadrnezhaad, S. K ; Sharif University of Technology
Abstract
ZnO nano-architectures were produced with the aid of a fast, simple and low cost microwave-assisted synthesis method. Solid semispherical ZnO nanoparticles on the order of 600 nm in diameter along with rice-like ZnO nanorods 95 nm thick were produced from butanol, triethanolamine (TEA), and zinc acetate dihydrate. Solid spherical ZnO nano-architectures with an average diameter of 250 nm were produced from the same starting materials in addition to NaOH. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to characterize the ZnO nano-architectures as well as the precursor. This method is cheap, fast and simple; capable of producing large quantities...
Microwave-assisted synthesis of narcis-like zinc oxide nanostructures
, Article Journal of Alloys and Compounds ; Volume 497, Issue 1-2 , May , 2010 , Pages 325-329 ; 09258388 (ISSN) ; Zanganeh, S ; Kajbafvala, E ; Zargar, H. R ; Bayati, M. R ; Sadrnezhaad, S. K ; Sharif University of Technology
2010
Abstract
Through a fast, simple, low cost, surfactant-free and convenient microwave-assisted route, narcis-like ZnO nanostructures (10-15 nm size) with flower diameters in the range of 1-2.5 μm were synthesized. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and room temperature photoluminescence (PL) measurements were used to characterize the produced ZnO nanostructures. The principle raw materials - ammonium hydroxide (NH4OH) and zinc acetate dihydrate [Zn(CH3COO)2·2H2O] - were both inexpensive. The method was fast, simple and surfactant-free capable of producing larger quantities of zinc oxide...
Thermodynamic evaluation of adsorption of zinc complex and ZnO nano-layer prepared by tscd method based on langmuir adsorption model
, Article International Journal of Engineering, Transactions B: Applications ; Volume 22, Issue 2 , 2009 , Pages 179-184 ; 1728-144X (ISSN) ; Sadrnezhaad, S. K ; Sharif University of Technology
Materials and Energy Research Center
2009
Abstract
Zinc oxide thin films were deposited on soda-lime glass substrates from an aqueous zinc- containing complex by two-stage chemical deposition (TSCD) method. Longmuir adsorption model showed that the adsorption of atoms on the surface of the substrate was typically physical. The relation between the fractional coverage, θ, with the equilibrium constant of the adsorption reaction was nonlinear indicating that the adsorption was non-ideal. The percentage of porosity, 1-θ, of the thin layer was determined as a function of Zn 2+ concentration of the solution. By application of XRD technique, it was shown that pure crystalline ZnO of controllable thickness could be deposited by TSCD method on the...
High-Voltage, high-current electrical switching discharge synthesis of ZnO nanorods: A new method toward rapid and highly tunable synthesis of oxide semiconductors in open air and water for optoelectronic applications
, Article ACS Applied Materials and Interfaces ; Volume 13, Issue 39 , 2021 , Pages 46951-46966 ; 19448244 (ISSN) ; Abrari, M ; Karimi, V ; Shafiee, M ; Ghollamhosseini, S ; Taheri Ghahrizjani, R ; Ahmadi, M ; Wang, D ; Sun, H ; Soltanmohammadi, M ; Imani, A ; Ghanaatshoar, M ; Mohseni, S. M ; Taghavinia, N ; Sharif University of Technology
American Chemical Society
2021
Abstract
A novel method of oxide semiconductor nanoparticle synthesis is proposed based on high-voltage, high-current electrical switching discharge (HVHC-ESD). Through a subsecond discharge in the HVHC-ESD method, we successfully synthesized zinc oxide (ZnO) nanorods. Crystallography and optical and electrical analyses approve the high crystal-quality and outstanding optoelectronic characteristics of our synthesized ZnO. The HVHC-ESD method enables the synthesis of ZnO nanorods with ultraviolet (UV) and visible emissions. To demonstrate the effectiveness of our prepared materials, we also fabricated two UV photodetectors based on the ZnO nanorods synthesized using the subsecond HVHC-ESD method. The...
ZnO-incorporated polyvinylidene fluoride/poly(ε-caprolactone) nanocomposite scaffold with controlled release of dexamethasone for bone tissue engineering
, Article Applied Physics A: Materials Science and Processing ; Volume 128, Issue 8 , 2022 ; 09478396 (ISSN) ; Mohammadi, M ; Mashayekhan, S ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Here we report on the development of a hybrid nanofibrous scaffold made from polyvinylidene fluoride (PVDF) nanofibers embedding zinc oxide nanorods (ZnOns), and poly(ε-caprolactone) (PCL) nanofibers incorporating dexamethasone (DEX)-loaded chitosan nanoparticles using dual-electrospinning method. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and tensile analysis were carried out for physiochemical characterization of the scaffolds, followed by DEX release profile. In addition, an MTT assay was conducted to assess the viability of mouse bone marrow-derived mesenchymal stem cells (mBMSCs) on the hybrid nanofibrous scaffold....
Numerical Simulation, Tunability and Experimental Investigation of Random Lasers and Using ZnO Nanosheets in these Lasers and UV Photodetectors
, Ph.D. Dissertation Sharif University of Technology ; Mahdavi, Mohammad (Supervisor) ; Bahrampour, Ali Reza (Supervisor) ; Taghavinia, Nima (Co-Advisor)
Abstract
In this thesis, first, random lasing in a three dimensional disordered medium has been simulated using FDTD method and some properties of random lasers which were observed by others in the previous experiments have theoretically been shown. Our simulation results show that when the density of particles increases to an upper limit, the intensity of lasing modes is enhanced. Also, the effects of pumping rate and particle size on the number of lasing modes and their intensity are studied. Lasing threshold of laser modes in different disordered systems is calculated and it is shown that by an appropriate selection of the central frequency of gain line-shape, the output power intensity of random...
Kinetic Investigation of the Degradation of Environmental Pollutant in the Presence of TiO2 Nanoparticle on Carbon Nanotube
, M.Sc. Thesis Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor) ; Rahman Setayesh, Shahrbanoo (Co-Advisor)
Abstract
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...
Kinetics Investigation of Photocatalytic Degredation of Environmental Organic Pollutants Using ZnO-Zeolite Nano Composites
, M.Sc. Thesis Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor) ; Sajadi, Ali Akbar (Supervisor)
Abstract
ZnO nano particles and mordnite zeolite nano particles were prepared by precipitation method and hydrothermal method,respectively. The influence of solvent and surfactant in ZnO nano particles synthesis were studied to reform the structure of nano particles.These nano particles were based on different supports to improve and enhance their photocatalytic activities. Synthesized catalysts characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform-infra red spectra (FTIR), UV-Vis spectroscopy and BET techniques. To investigated photocatalytic activity of the synthesized catalysts under UV irradiation, they were used to degradation bio-environmental...
An Investigation into Effects of Components Ratio and Nano/micro Sized ZnO Particles on Evolution of Transesterification Reaction, Compatiblization and Modification of PET/PC Blends Structure
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor) ; Pircheraghi, Gholamreza (Supervisor)
Abstract
Polycarbonate (PC) and polyethylene-terephthalate (PET) are important engineering thermoplastics. During last decades these polymers and their blends have been studied extensively due to their wide range of applications. Blends of PET and PC combine mechanical properties and chemical resistance together, which make applicable in various components such as automotive, electrical and of medical parts. It has been accepted that PET/PC immiscible blends are subjected to transesterification reactions during thermal processing, which produces PET-PC copolymer chains. In fact, scissioning and substitution of ester/carbonate functional groups of PC and PET at the interface, transforms the initial...