Sharif Digital Repository

In this study, Al6063-Al203 nanocomposite powders were synthesized by reaction mechanical milling method. Nanometric reinforcement particles were formed via high- energy ball milling under a controlled oxygen containing atmosphere. Morphological and microstructural evolutions of nanocomposite powders were investigated by using X-ray diffraction (XRD), thermal analysis (DTA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods at different milling times. The results showed that mechanical milling stages were accelerated and the time for reaching steady- state condition was decreased by an increase in the oxygen content in the milling atmosphere. The in-situ... 

In this study designing and manufacturing of high-temperature fluidized bed reactor were performed. These reactors are based on the contact of fluid with solid particles and balancing the weight of the solid materials. In the manufactured reactor, reduction of manganese de oxide to manganese oxide was done by carbon monoxide produced from incomplete combustion. The most important parameters in the reduction rate are: bed temperature and reduction gas concentration. Materials were injected into the reactor under the pressure of 1.13 mmHg and temperature of 787 ℃ in the bed depth of 4 cm for 2 hours and then the product was removed. XRD patterns showed that the dominant phase in the product... 

In this project formation of MgO & Mg2Cu reinforcement particle in Magnesium matrix was investigated. Firstly Mg & CuO powders mixture in different weight percentage (4, 8%wt CuO) in 20:1 and 30:1 BPR were milled. Finally, according to XRD result 30:1 BPR was selected for milling. Variations in powders morphology, particles size, crystallite size, lattice strain and phase transformation were investigated by X-ray diffraction, scanning electron microscopy and laser particle size analyzer in different milling time. Result showed that during reaction between Mg and CuO, MgO & Mg2Cu reinforcement particles were formed in matrix. Matrix crystallite size was determined about 35-40 nm. Mg-6.3%wt Cu... 

Molybdenum disilicide is an intermetallic compound in Mo-Si binary system that has very applications because of its individual properties. High melting point of MoSi2 limits the fabrication of this compound by conventional methods. Nowadays modern techniques such as Mechanical Alloying are used for synthesis of Molybdenum disilicide. In this investigation the MoSi2 has been synthesized from the elemental powders by Mechanically activated Self propagating Reaction method and the effect of milling atmosphere on synthesis efficiency is discussed  

The global energy outlook has been altered as a result of mounting concerns regarding fossil fuels. Electrocatalysts have become a favorable alternative for renewable energy production processes, particularly in the fields of hydrogen evolution reactions (HER) and oxygen evolution (OER). This study focuses on the production and enhancement of nanocatalysts, specifically materials based on ZIF-67, for the purpose of water splitting. The initial phase included the synthesis of the ZIF-67 structure through the simple room-temperature coprecipitation process, utilizing cerium as a dual-metal component. The molarity of the cerium was optimized in the ZIF-67 framework to achieve the most desirable... 

One of the model based control strategies that has been proposed in recent years for the control of process systems is the one based on the economic models, in which objective functions with an economic basis are used along with the equations and constraints to perform control calculations. In this work, the control of a multiproduct continuous stirred reactors is discussed, in which, it is possible to produce different products based on changes in the market demand, the price of the products or the primary raw materials according to a specific schedule. One of the recently used methods is the economic predictive control method based on the Lyapunov function. In this method a quadratic... 

Osteoarthritis has always been one of the most common diseases in middle age because it causes severe pain and inflammation in the joints of the body. Cartilage tissue does not have the ability to repair itself. For this reason, fabricating and designing the most efficient, least-expensive, and most convenient methods for the treatment of cartilage defects is always an important issue. Today, there are surgical and injectable methods to relieve pain and initiate the body's natural healing response. But due to the many disadvantages and limitations of these methods, tissue engineering science has turned to modifying these methods or providing new methods. One of these methods is the use of... 

Today, due to the decreasing of fossil fuel reserves and the need to use clean fuels, hydrogen is a suitable alternative, and hydrogen production has received considerable attention. One of the best methods of hydrogen production is water splitting. Overall water splitting can be divided into two half reactions including the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which selecting the appropriate electrocatalyst for these half reactions plays an important role. The four-electron transfer process in OER leads to slow kinetics of the reaction and a large overpotential. The noble metal-based oxides, including IrO2 and RuO2, are known as outstanding OER... 

Photoelectrochemical (PEC) water splitting is exceedingly promising for converting solar energy into molecular hydrogen as a clean and sustainable fuel. However, the overall rate of water splitting reaction is severely limited by the sluggish kinetics of the anodic half-reaction, namely, the oxygen evolution reaction (OER). Bismuth vanadate (BiVO4) is a popular photoanode for PEC water splitting due to its high stability, low cost, narrow band gap (2.4 eV), high visible-light absorption, and environmental compatibility. However, BiVO4 suffers from poor charge transfer, fast recombination of electron-hole pairs, and inferior catalytic activity toward OER. An effective strategy to overcome... 

Ti-UIO-66(Zr) nanocomposites have been prepared via a modified one-step solvothermal methodology and evaluated in photocatalytic oxidative desulfurization. Extensive characterization by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence spectroscopy (PL), nitrogen adsorption-desorption, and thermogravimetric analysis (TGA), have revealed the role of Ti loading, on Ti speciation and the structure of the composite materials. Their performance have been... 

The aim of this project is to inventigate and synthesize CaO-based nanocatalysts with metal promoters of magnesium and lithium by wet impregnation and coprecipitation methods, which are used in the transesterification reaction of canola oil and methanol. Sections of thesis include review of before researches , synthesis of nanocatalysts, catalyst characterization tests,and investigation of reaction under optimal conditions. In wet impregnation method, nanocatalysts were made with 5% by weight of lithium-magnesium on the basis of CaO and with different weight percentages of these two elements. In the co-precipitation method , catalysts with a combined base of calcium oxide/magnesium oxide ... 

The aim of this project is to fabricate and study heterogeneous CaO-based nanocatalysts with lithium and zinc enhancers for the esterification reaction of rapeseed oil and methanol to produce biodiesel as a renewable and alternative fuel for fossil fuels. Is. First, Zn-Li / CaO catalysts with weight ratio Li: Zn: CaO, 2: 2: 7 and by combining different percentages of Li100% promoter, Li75% -Zn25%, Li50% -Zn50%, Li25% -Zn75%, 100% Zn were made on the basis of CaO by wet inoculation. Characterization tests to evaluate the structure and characterization such as X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (EDX) spectroscopy, Bruner-Emmett-Teller... 

Considering the world's diminishing oil reserves, as well as the growing demand for oil and energy consumption, Enhanced Oil Recovery (EOR) techniques are becoming increasingly important in the attempt to improve oil production. Engineering salinity waterflooding has gained widespread attention and popularity in the last two decades due to its environmental friendliness, lack of expensive additives, low operating costs, and ease of use as an oil extraction process. The goal of this study is to use an innovative method to develop a mechanistic approach model that simulates and forecasts the mechanism and performance of the engineered water flooding process. Wettability alteration, the most... 

Injection of acid into the carbonate rock dissolves the rock, and the porous medium is constantly changing. As a result, the boundaries between the acid and the porous medium, which are in fact the interface between the solid phase and the liquid phase, are constantly changing. Therefore, on the issue of acid injection into carbonate rock, we are facing dynamic boundary conditions. Also, due to the simultaneous solution of transfer and reaction phenomena, modeling acid injection into carbonate rock faces many challenges.In such problems, the ALE method, which is a combination of the best features of the Lagrangian method and the Eulerian method, offers a very precise solution and is used as... 

Zinc-bromine redox flow batteries are promising for large-scale energy storage applications due to their high energy density and open-circuit voltage. Proposed models for predicting these batteries' performance are limited due to challenges such as zinc deposition during the charging step and the utilization of a complexing agent. In this study, a 2D dynamic model was developed to investigate the battery performance. The kinetic equations for half-reactions are considered according to their two-step electron transfer mechanism. The model predictions were validated against experimental data reported in the literature for different current densities. Afterward, effects of various operating... 

In this study, the viability of handling flue gas streams as a source of CO2 for the thermocatalytic conversion was investigated as a CO2 emissions reduction strategy and an intermittent energy storage solution. A transient mathematical model for dynamic catalyst deactivation was validated with experimental results and then used to study HEX membrane reactor. A simulation-based study of novel Sabatier reactor configurations was performed to study the effect of distributed H2 supply on Ni-based catalyst deactivation and to optimize the production of CH4. First, a heat-exchanger type, actively cooled Sabatier reactor is analyzed using a transient mathematical model to assess its feasibility.... 

Nowadays, due to increasing attention to produce a wide range of fuels through bioprocesses, in the present work, simulation and control of a continuous reactor to produce biodiesel from food-wastes has been addressed. In this regard, the transesterification reaction of triglyceride (a mixture of 10% (wt) Jatropha oil and 90% (wt) of edible oil residue) with methanol (6:1 molar ratio of methanol to oil) in the presence of 1% (wt) potassium hydroxide catalyst in a continuous stirred tank reactor has been simulated. For the control purposes, the bioreactor temperature and the product concentration have been controlled by manipulating heat duty and reactant feed flow rate, respectively. An... 

Acidizing operation is performed in oil and gas reservoirs with the aim of overcoming formation damages, increasing permeability and reducing skin factor. In carbonate reservoir, the hydrochloric acid increases the permeability of the areas around the well to a more than its initial value by dissolving part of the formation minerals. Considering that most of Iran's oil and gas reservoirs are in the category of carbonate reservoirs, it is important to study the reaction kinetics of carbonate minerals and acids used in acidizing operation. The complex and multifactorial nature of the acidizing operation in the reservoirs has made it very difficult to design a successful and optimal operation.... 

Polymerase Chain Reaction (PCR) is a process in which a special piece of a gene is amplified millions of times over a short period. This method has been of paramount importance in different fields of research and has been applied for different applications. PCR requires thermal cycling, or repeated temperature changes between two or three discrete temperatures to amplify specific nucleic acid target sequences. To achieve such thermal cycling, conventional bench-top thermal cyclers generally use a metal heating block powered by Peltier elements or benefit from forced convection heat transfer. Due to the fact that these methods are time consuming, it seems that design and fabrication of a fast... 

Volatile organic compounds (VOCs) has harmful environmental and health effects and appropriate processes are needed to remove them from industrial and indoor environments. In this study, formaldehyde as one of the most toxic VOCs was investigated. Various methods have been developed to remove formaldehyde, however due to the to their low removal efficiencies, secondary pollution, and low energy efficiency, development of alternative methods will be beneficial. In recent years, the use of a combination of non-thermal plasma and catalyst technologies, called plasma-catalytic hybrid reactors, has provided significant results in the fields of chemical synthesis and removal of pollutants. In the...