Sharif Digital Repository

The present thesis has provided more fundamental understanding of granulation rate processes (such as coalescence, attrition and breakage) by investigating the effects of operating parameters on product properties. The studied process was wet granulation carried out in two high shear mixer granulators. Granulation duration, binder mass and impeller speed were considered as operating parameters and granule size distribution (measured by sieving) and granule binder distribution (measured by thermogravimetery method) were regarded as product properties. Experiments were conducted in two analogous cylindrical and conical high shear granulators. The obtained experimental and theoretical results... 

The properties of 3 nm-diameter fluorinated silica nanoparticles with different coverage percent of CF3 groups as water and oil repellents were investigated at the water-rock and decane-rock interface using molecular dynamics simulation. Simulating a pore of rock in presence of water and decane molecules separately, resulted in liquid bridging for both of liquids. The density profiles of liquids in the pore clearly show several highly ordered layers packing of the molecules close to the rock surface. Distribution of liquid molecules around the nanoparticles is much influenced with increasing CF3 groups on the nanoparticle surface. Results show that adsorption of functionalized silica... 

The effects of biosurfactants on sandstone rocks are known in the literature. However, there are few examples of experimental works in Iranian carbonate reservoirs dealing with the effects of biosurfactants under reservoir conditions. This thesis discusses the effect of an efficient biosurfactant produced from Pseudomonas aeroginosa MRo1, a bacterial strain isolated from oil excavation areas in southern Iran, on the recovery of residual oil trapped within carbonate rocks was investigated. The MRO1 could reduce surface tension from 72 to 28 dyne/cm. It also could reduce Interfacial tension from 18.382 to 5.646 dyne/cm.
In a core holder set-up bearing four limestone- and... 

Management and reservation of mine tailings are among the most important problems in today’s engineering. Among the different kinds of mine tailings, wet tailings are of the most critical ones due to their slurry shape. In addition to their different form of settlement than normal kinds of soil, they can easily transfer the pollutants through their base to the adjacent areas. Therefore, investigation of their sedimentation and consolidation processes is necessary. In this thesis, it has been tried to program a code according to the literature, in order to simulate the sedimentation and consolidation process of wet tailings. The mathematical method that has been used in the thesis for solving... 

One of the common methods used for treatment of gaseous radioactive wastes in nuclear waste management is adsorption process. Nanoporous materials have found great utility as sorption media because of their large internal surface area and more adsorption sites than other adsorbents, which caused the increasing attention of researchers to use them in the nuclear waste management. Hence in this study, the surface of nanoporous silicates of SBA-15 and MCM-41 modified with d-block elements of the periodic table such as silver, copper, zinc and nickel by wet impregnation method. After characterization by different techniques such as X-ray diffraction, nitrogen gas porosimetry, Fourier... 

Capillary Imbibition is an important mechanism in producing oil from matrix blocks in fractured reservoirs. In a water-wet fractured reservoir, if the rise of water level in fracture is in a way that at all the moments the water front in fracture is lower than that in the matrix block we expect co-current imbibition. Iranian reservoirs have large matrix blocks and co-current imbibition can be expectable. Till this time, not many investigations have been done on co-current imbibition in and out of our country, Iran. In this thesis, an experimental investigation on co-current imbibition will be done for different conditions. The main goal of this thesis is the study of co-current imbibition in... 

There is increasing evidence that injecting modified brines has a significant impact on the amount of oil recovered, but the exact mechanism by which this occurs is an unsettled issue, and is supposed to be a cause of the complex interactions occurring between the phases insitu. In this thesis, surface chemistry of smart water has been investigated. Fluid/solid and fluid/fluid interactions for Bangestan crude oil in tfhe presence of designed solutions and a set of dilutions of Persian Gulf seawater have been studied and compared. Fluid/solid interactions were investigated through wettability studies. Impact of salinity and ionic composition on this interaction was measured through contact... 

Laboratory studies to investigate the effects of different saline concentrations (such as sodium chloride or calcium chloride) on the soil water retention behavior of clayey soils and their volumetric changes have received much attention recently. However, many previous studies have investigated these effects in only one path of the SWRC (wetting or drying path) and the effects of saline concentration on hydraulic hysteresis have not been considered. In addition, researchers have frequently studied these effects on SWRC on clay samples, and little research has been done on collapsible soils. Therefore, the most important purpose of this study is to investigate the effects of increasing... 

In general, the output power of the gas turbines decreases as the ambient temperature increases. One of the ways to deal with such a performance loss is to use a wet compression system, which reduces the air temperature rise throughout the compressor. In this system, the water droplets are injected into the compressor inlet and evaporated throughout the stages. As a result, the work of the compressor decreases, and the power and efficiency of the whole engine increase. Most of the researchers in this field have tried to develop mathematical models to investigate the effects of this system on compressor and gas turbine performance in steady-state conditions. However, it is necessary to... 

In the present work, wet air oxidation of phenol over 7/3 MnO2/CeO2 composite oxide catalyst in trickle-bed and packed-bubble column reactors was modeled. Complexity of wet air oxidation reactions and catalyst poisoning with carbonaceous groups, on the surface and in the pores of catalyst, make the modeling process complicated. Plurality of mass balance equations which are confirmed in the catalyst pellet and in dynamic and static bed phase, also the equation of catalyst deactivation, lead us solve them simultaneously. In addition, the equations are two dimension and unsteady state and carbon of oxidation intermediates are present which make the modeling process more complicated. We are... 

This study investigates three-dimensional modeling of nanodroplets over chemically patterned surfaces. The pattern can be established by changing the contact angle on the surface. The problem is studied numerically by solving the thin film equations.Both the long-range and short-range inter-molecular interactions are considered. The numerical procedure is validated by using the theoretical studies. The effects of parameters such as the size of the droplets, the gradient of the surface, and the slip coefficient on the dynamics and speed of droplets and the shape of them during the motion are inspected.By examining the dynamics of the system it is revealed that the velocity of the droplets... 

Transition Metal Dichalcogenids (TMD) are types of 2D materials that exibit wide range of electronic, optical, mechanical, chemical, and thermal properties. These materials with MX2 general formula, have atract attentions with respect to their unusual properties because of their very limited dimensions. Their tunable properties and materials availibility make them attractive for wide range of applications. In recent years, chemical vapor deposition (CVD) methods are promising in preparing high quality TMD with scalable size, controllable thickness, and very excellent electronic properties. Also, chalenges are remaining in synthesis and transfering of TMD are difficulty for most of... 

Quite a few methods have been reported to synthesize monolayer MoS2, which has recently attracted scientist attentions. Fully controlled conditions, however, have not been achieved in these methods. In this research, two-dimensional MoS2 nanofilms have been synthesized by Chemical Vaper Deposition (CVD). Layer thickness of synthesized layer and effects of various parameters of used method have been investigated. Although every scientist synthesizes 2D MoS2 at 650°C in the CVD method by using seeds, in this research, it has been proved that MoS2 nanofilms can be produced at 575°C without using any seeds, which leads to lower consumption of time and price and increases the quality of... 

Due to population growth, the demand for water supply has increased. This need has drawn attention to the use of consumed and treatable water resources. Organic pollutants are a key source of water pollution. On the other hand, petrochemical oil pollution and frequent oil accidents during oil production or maritime transport have become one of the environmental problems.There are different methods for water and oil separation and water purification that in the present project, selective separation can be achieved by using hydrophobic materials and surface roughness and creating surfaces with two properties: superhydrophobic and ultra-oil friendly. This method is also very effective, cheap... 

The aim of this study is to develop an understanding of the role of the magnetic and electric forces on the filtration performance of wet granular beds. At first, the effect of wetting is considered by locating micro water film around the square channel for particles deposition in four different Reynolds Re=1 to Re=10 number, Typically 1000 particles in different sizes (100nm-10μm) were injected to microchannel when air and water formed completely on the surface of the block. The Drag force, Brownian force, Saffman`s lift force and the gravity force are affecting the particles. After that Dielectrophoretic and Magnetophoretic forces were included in the domain for investigating the role of... 

The light emitting diodes is composed of an electron transport layer and hole transport layer. The electrons and holes go to the middle region called active region through these transmit regions, and they emit light from themselves by recombination in this area. In our structure, the active region consists of quantum dots. The emitted light characteristics depend on these dots to great extent. In this thesis, we first describe the processes in this type of device, and then we will review the well-known structures that have been reported so far. In chapter 4 discusses the important characteristics of the active region, including the size of the quantum dots and the wetting layer, and we... 

Two-phase fluid flow physics in porous media is applied in various fields. Studies have shown that wettability and surface tension, which represent fluid-rock and fluid-fluid interactions, have a significant effect on the dynamics of the immiscible displacement. Although the effects of wettability and surface tension on the macroscopic behavior of fluid flow are known, there is less understanding of it at the micro scale. Considering the essential role of wettability and surface tension in various fields, this project seeks to investigate the effects of wettability and surface tension on the movement and distribution of fluids and the dominant displacement mechanisms within the porous media... 

In the past decades, electrospinning has been widely used for the production of micro/nanofibers. In spite of the simplicity and effectivity of the conventional electrospinning for fabricating nanofibers, compact structure and small pores of the nanofibers hinder the efficient penetration of analytes during the extraction process. In order to overcome this issue, an applicable strategy called wet electrospinnig has been employed to enlarge the pore size of the electrospun scaffolds. By applying this technique, a collector was placed at the bottom of a solvent bath and highly porous foam from polyamide nanofibers was produced immediately after freeze-drying (3D electrospinning).... 

To explain the dependence of sliding friction on or between the layers of wet sand, one first needs to have a rather good understanding of the elastic properties of wet granular material. Experimental work that has been done on the subject so far, has shown that these elastic properties have a peculiar dependence on the water volume fraction of the sand system. But till nowno theoretical model has been presented that could illustrate the physical causes of such findings. More specifically, these handful of theoretical models have not been able to explain the complex relationship between the shear modulus of sand and the water volume percentage. In this thesis at first the nature and... 

Uranium is the most important element in the nuclear fuel cycle. Recovery of uranium from waste produced at every stage of the fuel cycle is not only economically important, but also environmentally important. In the production phase of uranium hexafluoride, certain amount of solid waste is produced in the bottom of the fluorination reactor. In order to extract the uranium from this waste, we have to eliminate the fluorine contained in the waste. This is because the fluorine forms strong complex with uranyl ions during the extraction process, and prevents from efficient extraction of uranium. In the current thesis؛ first, we examined the characteristics of the waste ...