Sharif Digital Repository

For designing a unit operation, knowledge about physical properties is essential. This is attained either by direct measurement, which needs spending time and cost or, using proposed correlations. This project is subjected to theoretical analysis of viscosity as the most important rheological property of dilute suspensions of microgels, or in other words colloidal suspensions of porous spheres. They are applied in drug delivery, enhanced oil recovery, synthesis of catalyst and adsorption of heavy metal ions from aqueous systems for water purification purposes. In dilute suspensions particles are faraway from each other and there is no interaction between them therefore, it is better to... 

Continuous separation processes in microfluidic devices experienced a steep rise in attention during the last two decades. Among the different separation processes, liquid-liquid extraction especially benefits from the short molecular diffusion distance and large specific interfacial area, as these are advantageous for effective mass transport. In the present study, glass-based microfluidic devices have been fabricated utilizing laser ablation and wet chemical etching methods then experiments and numerical simulation were carried out to investigate hydrodynamic behavior of fluid flow in Y-junction microfluidic. In order to achieve phase separation at the end of the microchannel, a phase... 

Surface modification is an important property of nano particles. In this project surface of silica nano particles modified with hydrophobic and hydrophilic groups to imrprove surface activity of nano particles. Purpose of this project is to study surface activity of surface modified silica nano particles in different temperatures from 20 to 70 degree centigrade. Also effect of salt and time on the surface activity is studied. At first nano particles modified just with haydrophobic groups and then just with hydrophilic groups (hydrophobic and hydrophilic nano particles) and after that, the surface modification done with both hyadrophilic and hydrophobic groups (amphiphilic nanoparticles).... 

The aqueous phase reforming (APR) of glycerol is an attractive yet challenging pathway to convert abundant biomass into value added hydrogen. Pt catalysts have received attention due to their ability to produce hydrogen-rich gas under APR conditions. In this work, the conversion of glycerol into hydrogen is demonstrated using Pt0.05CexZr0.95-xO2 (x=0, 0.29, 0.475, 0.66 and 0.95) solid solution catalysts and a series of M-doped Pt-MgO (M = Pd, Ir, Re, Ru, Rh and Cr) sheet-shaped nano-catalysts. Both characteristic (XRD, BET, H2-TPR, CO-chemisorption, TEM and XPS) and reactivity measurements were used to investigate the activity of the catalysts. Results indicated that reactivity depended on... 

The main purposes of this project are simulation, design, and fabrication of a microfluidic system based on dielectrophoresis (DEP) exploiting AC voltages for separation of microparticles. Generally, this project can be divided into two parts. First, the engineering section including design and fabrication of microchip, and second biological samples preparation for investigating the system performance. The main advantages of proposed system are eliminating joule heating, a significant problem in insulating based dielectrophoresis systems, overcoming problems related to metal contamination in biological samples, the main problem of conventional dielectrophoresis platforms, and removing... 

The main goals of this research are design, simulation, and fabrication of a microfluidic system working based on dielectrophoresis. This research divided into two different parts, the first of which is the simulation of a microfluidic system, and second of which is an attempt for fabrication of microfluidic system. For the fabrication of the microfluidic system, different methods were used. In the simulation part, the enrichment of different particles was investigated, and the effects of different parameters on the enrichment were assessed. It was observed that as flow rate increases, the enrichment amount diminishes. Furthermore, as the microfluidic depth decreases, the enrichment amount... 

The present paper is an attempt to critically measure interfacial tension with microchannels and achieve the quantity of adsorption in the liquid – liquid interfaces and comparing the adsorption of surfactants and nanoparticles surface modificated as well. At this point we need to make emulsion and it is necessary for droplets to be monodispersed due to analyze these droplets in this paper. According to this condition for our droplets microsystems are the best options. As we know surfactants were already known as a stabilizing emulsion agent and in this paper nanoparticles are suggested as suitable alternatives for surfactants which can be absorbed as if they are in the water / oil... 

Nanoparticles can be applied as chemical agent in enhnaced oil recovery like surfactants and polymers. One of nanoparticles usefull capabilities is modification of their surface. This research investigates this capabilty of nanoparticles in enhanced oil recovery. Surface modification of nanoparticles with both agents can bring new abilities to these materials. Here surface of silica nanoparticles is modified by hydrophilic agent comprising PEG groups, hydrophobic agent comprising propyl group and both agents. FT-IR tests showed that grafting of modifiyng agents on surface of nanoparticles is well done. To investigate effect of nanoparticles surface modification on nanoparticles capability in... 

Gas pollutants are included volatile inorganic compositions and odorous materials, which are harmful and dangerous for environment and human health. There are several methods for removing gas pollutants such as physical, chemical and biological methods. In this work, we discuss about ethyl-mercaptan adsorption in LPG by ZSM-5 zeolite and in use of micro systems (micro channels). This work is also concerned about micro channel coating by ZSM-5 and NaY zeolites on glass and the method of coating with (3-Chloropropyl) trimethoxysilane linker. After selecting the appropriate method for zeolite coating, we proceed to micro channel coating. In this research, four different designs of micro channel... 

Today, with the development of micro-technology in chemical reactions, the use of appropriate systems for the separation and purification of synthesized chemicals seems to be necessary. In this study, the continuous synthesis of bromide-lithium exchange reaction and the separation of organic and aqueous phase products in micro systems was investigated.The method used to construct micro-separator and micro reactor, a laser engraving technique, and thermal bonding of glass to glass.In the first step, the factors affecting the separation of organic and aqueous phase in the capillary micro-separator, such as the width of the capillary, the length of the capillary, the number of capillaries and... 

The produced crude oil from the petroleum reservoirs usually has a value of brine (water and salt) this matter can be caused the corrosion of refinery equipment. The large part of this brine creates a stable emulsion with oil, that it couldn't be separated easily. For separation and demulsification of this emulsion, some chemical, mechanical, thermal and electrical methods can be executed. In chemical method, demulsifier materials can be added to water-in-oil emulsion. Different parameters such as properties of oil, type and concentration of demulsifiers, volume factor of water and etc., can affect the efficiency of water-in-oil emulsion separation. In this study, emulsification mechanism,... 

Lately, some investigators of polymer engineering group are working to do continuous polymer solution casting process, rather than batch process for flat sheet membrane production. For this, they use a doctor blade system but, they faced some problems during coating process. From experimental observations of the studied system, some inappropriate vorticities were seen. That’s why the system forms a non-uniform film of the solution. Air bubbling occurs at system exit which is undesirable as well. In this study simulation and optimization has been done for forming thin film in doctor blade system. COMSOL Multiphysics 4.3b was used in purpose of simulating which works on numerical finite... 

Important features of the nanoparticles properties are their high superficial area and being able to reform their surface. In this study, the repairable property used to reform surface of silica nanoparticles (Those are used more frequently than other nanoparticles). Repairing of surface are doing to use nanoparticles as a surface-active material in enhanced oil recovery. Silane compounds with different chain length are used to create hydrophobic nanoparticles and PEG compounds are used to create hydrophilic nanoparticles. Also amphiphilic nanoparticles are created with a combination of both hydrophilic and hydrophobic compounds. To investigate the usefulness of nanofluids are made up of the... 

The purpose of this study is to study heterogeneous nanocatalysts for the production of biofuels by the method of exchange of styrene using oil and methanol as a fossil fuel alternative. Preparation of nanocatalysts, performing characteristic tests and investigating the reaction in different operating conditions in the batch reactor has already been studied. Therefore, in this study, the production of biodiesel fuel using the trans-esterification of canola oil with nanocatalysts in the micro-reactor reactor will be discussed. Previously, a heterogeneous catalyst (lithium based on calcium-lanthanum) was constructed using a co-incineration method and a wet inoculum, and as active and stable... 

In this study, the dynamics of microparticles in a straight microchannel in the presence of an inhomogeneous oscillating electric field have been simulated by the immersed boundary method in combination with the lattice Boltzmann Navier-Stokes solver and the lattice Boltzmann method for solving the Poisson equation. The effect of the electric field on the location and number of particle equilibrium positions have been examined. In the absence of the electric field, circular particles will migrate to two stable equilibrium positions. The site of these equilibrium positions depends on the particle size and the fluid flow rate and is independent of the particle density. In the case of negative... 

Due to the potential risk of sulfur compounds in fossil fuels and according to today’s regulations, sulfur content should be kept as low as possible, e.g., below 5 ppm. Mercaptans are one of the sulfur components in natural gas. Scope of this research defined as catalytic removal of ethyl mercaptan from the gas stream. For this purpose, two microreactor systems placed in series. In the first microreactor, catalytic decomposition of ethyl mercaptan has been investigated. In the first step of this survey, a microreactor with 24 microchannels with a newly designed distributor has been developed with a computational fluid dynamic technique. in comparison to the conventional triangular... 

In recent years, desulfurization has received much attention due to its devastating environmental effects. The existence of sulfur compounds has effects such as corrosion, poisoning of catalysts, reduction of heat of combustion and reduction of price. Sulfur compounds in hydrocarbon fuels also produce sulfur oxides caused by combustion then they enter the atmosphere, and cause acid rain. Acid rain dissolves building materials, poisons lakes, and destroys forests. Therefore, removing sulfur or converting it to less harmful substances is one of the most important processes in refineries. The method studied in this research is the use of adsorption desulfurization method by microchannel which... 

With rising oil prices and predictions about the future of hydrocarbon reserves, issues of enhanced oil recovery and optimal production of existing reservoirs are of particular importance. In this study, molecular dynamics simulation was used to study the absorption of silica nanoparticles with surface groups at the interface of water and decane. The effect of surface chemistry of silica nanoparticles on the interface properties of water-decane with changing the surface groups was simulated. The initial surface factor of nanoparticle is hydroxyl (OH), which is called a hydrophilic surface agent. Nanoparticles were modified by methyl and ethyl surface agents to increase the hydrophobicity and... 

Separation of particles and cells is one of the most important and practical methods in fields such as biomedicine, medicine and industry. In microfluidics There are various methods for particles and cells separation According to the source of them, they can be categorised as active and passive techniques. Active techniques rely on an external force field. The most important advantage of this method is controlling the force on the particles during the experiment. However, the flow speed is always limited because particles must be exposed to the outer force field for sufficient duration to achieve effective functionality. passive techniques depend entirely on the channel geometry or intrinsic... 

% of human blood makes up of plasma, that this plasma is a rich source of proteins that can be used as biomarkers for a variety of clinical diseases and laboratory research, therefore, it is necessary that the plasma be separate by a high purity percentage. Using a centrifuge It is a common method used to separate plasma from blood, but because it requires large equipment and a large volume of blood, as well as stress caused by centrifugal force, increases the probability of damage to the biomarkers, so it has been tried today that Use methods that are easy to transport and require a small amount of blood. The idea of using the microfluidic device has been put forward for the purpose of...