Sharif Digital Repository

In recent years, application of silica nanoparticles for wettability alteration of reservoir rocks as an effective approach in enhancing oil recovery from petroleum reservoirs is introduced. However, in this area, lack of fundamental studies to provide a clear understanding about the interaction between these nanoparticles and carbonate rocks (as the predominant reservoir rocks in the world and Iran), which is of particular importance, is sensed. Therefore, the main purpose of this dissertation is to present a mechanistic investigation about the interaction of silica nanoparticles (the most used nanoparticles) with carbonate rock from theoretical and experimental viewpoints. To better... 

The main purpose of this project is synthesis of the silica nano-sheets by means of microfluidic techniques. Continuous process, precise control of reaction condition, and higher production rate can be considered as main pros of silica nano-sheets synthesized by microfluidic platforms. General method can be explain as follow: first two oleic and aqueous phase are injected to the microfluidic system, then oleic phase breaks down in aqueous phase drop-wisely and by performing sol-gel reaction on the oil-water interface a silica crust is made on oil droplets. Eventually, oil droplets are left the system and broken down and silica nano-sheets are made. FESEM and microscopic images of... 

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... 

In this study, polyelectrolyte-coated magnetic silica nanocomposites were prepared via the covalent attachment of polyelectrolytes onto the as-prepared magnetite-silica particles with core-shell structures and average diameter of 210±50 nm, and subsequently applied for the immobilization of lipase molecules. In this regard, polyethyleneimine (PEI) with two molecular weights of 10000 and 750000 and polyacrylic acid (PAA) with two molecular weights of 1800 and 100000 were utilized. The type and molecular weight of the polyelectrolyte molecules greatly impacted the concentration of binding sites on the particles surface and consequently on the lipase immobilization efficiency and loading... 

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... 

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... 

Tumor markers are substances that are naturally found in blood and other fluids in body, but in abnormal conditions such as cancer and metastasis, their level increase. The aim of researching about tumor markers is to find a way for discovering cancer only with a blood test and replace with the current methods such as ELISA, and any type of cancer can be detected by these tests. In this study, molecular imprinted polymers were synthesized with biomolecules. To do that, silica microparticles were used as solid base and after functionalizing their surface, a thin film of polymer was synthesized on them. To optimize the components concentrations and the polymer thickness on the silica surface,... 

Several studies based on anti- cancer, anti- metastatic and anti- tumor effects of curcumin have been reported . Besides these benefits, the therapeutic efficacy of curcumin is limited due to its poor aqueous solubility, extensive first-pass metabolism, inadequate tissue absorption and degradation at alkaline pH, which severely diminishes its bioavailability. In this project we seek to solve some of the problems with nanoscience to work more effectively. In the past decade, mesoporous silica nanoparticles (MSNs) have found widespread application as controlled drug delivery systems. Recent reports on the design of capped and gated MSN-based systems have shown promise in preventing premature... 

Enzymes are widely used in industry, however, the expensive cost, low stability, and the limited activity in a certain range of temperature and pH, have limited the usage of such bio-catalists. In addition to increasing and preserving their activity under different conditions, the enzyme immobilization can improve its stability in different pH, temperature values and increase its thermostability, storage stability and the possibility of their recycling. Meanwhile, utilizing the super-magnetic systems could be very helpful as well. For instance, separation of the the magnetic nano-particles like Fe3O4 from reaction system using an external magnetic field is easily possible. In this study,... 

This research aims to develop a drug delivery system based on mesoporous silica nanoparticles (MSNPs) for hydrophobic drugs and evaluating their cytotoxicity. The internal environment of the body is aqueous, while most of effective drugs display poor aqueous solubility, resulting in insufficient bioavailability. Due to their several unique properties, such as a large surface area, tunable pore size, facile surface multi functionalization and excellent biocompatibility, MSNPs are recognized as promising and powerful tools to overcome this hurdle. In the present study, MSNPs were synthesized using template removing method and then were functionalized through grafting procedure. They were... 

Phenolic compounds are important environmental pollutants that the removal and separation of them from the water and industrial wastewater especially in the oil industry is essential before entering the environment. In the present study, the removal efficiency of the adsorbent silica aerogel 4-Chlorophenol and 4-Bromophenol as phenolic compounds from aqueous solution was surveyed. In this research, the effects of various factors such as contact time, pH, and initial concentration of the pollutant and the adsorbent on the adsorption were studied. It was observed that there is a large amount of adsorption in acidic pH and this amount increases by incrementing the concentration of the... 

Mesoporous silica nanoparticles (MSNP) have attracted lots of attentions because of their particular characteristics. Physical characteristics such as structure, morphology, porosity, and size of these nanoparticles have strong impact on their function and it can be conceived a wide range of applications for them by manipulating these characteristics. In this research, monodispersed MSNPs with a controllable size in the range of 50-130 nm and pore size in the range of 4-24 nm were synthesized and positively functionalized in order to develop a carrier for the delivery of nucleic acids (siRNA and pDNA). The MSNPs were synthesized by the template removing method.In this method, sodium... 

Three sizes of silica nanoparticles (160±7, 450±10 and 600±25) were sythetized via template-removing method. The synthetized nanoparticles were functionalized with N-(2-aminoethyl)-3-aminopropyl trimethoxy-silane (EDS) to provide a positive charge on the surface of nanoparticles. BET analysis showed that the average pore diameter, surface area and pore volume of nanoparticles were 2.3 nm, 769 m2.g-1 and 0.44 cm3.g-1, respectively. showed that the Amine-functionalized silica nanoparticles were used to enhance the application of alginate polymer for 3D encapsulation of mammalian cells. Incorporating of silica nanoparticles can be suitable for the bead integrity and attachement of mammalian... 

Superparamagnetic core/shell nonporous (S1) and core/shell/shell mesoporous (S2 and S3) nanocomposite magnetite/silica particles with a magnetite cluster core of 130±30 nm, a nonporous silica shell of 90±10 nm thickness, and a mesoporous silica shell of 70±15 nm thickness were prepared thorough a simple method. Mesoporous particles were prepared with two BJH pore sizes (2.44 for S2 and 3.76 nm for S3 particles, respectively). The fabricated S1, S2 and S3 particles present high saturation magnetization values of 20, 13 and 17 emu/g, respectively. As a biological application, the lipase from Pseudomonas cepacia was successfully immobilized onto the amino-functionalized nanocomposite particles... 

Porous polymeric particles have the extensive application in various sciences and various methods have been introduced for production of these particles. Depending on method of production, porous polymeric beads can be produced in diverse shapes, pore size, pores interconectivity, surface morphology and chemical properties. In common methods for production of porous polymeric particles, tuning the size and porosity is difficult or even impossible. Porous polymeric beads with the vast surface area and good functionality have been applied for adsorption of various materials. The purpose of this study is therefore to investigate a new procedure for the production of porous polymeric... 

The main object of this thesis is production and investigation of polypropylene-fumed silica nanocomposites by using bi-supported Ziegler-natta catalytic system and in-situ polymerization. Magnesium ethoxide and fumed silica were used as supports of catalyst. TiCl4 was accompanied by triisobutyl aluminum(TiBA) and diisobutyl phthalate(DIBP) as electron doner constituting Ziegler-Natta catalytic system. Preparation of catalyst and polymerization were taken place in slurry phase under the argon atmosphere. At the beginning of the polymerization experiment, several type of nanocomposites were made under various conditions(such as different Al/Ti molar ratio) to find optimum condition to... 

In this study, thermal and rheological properties of nanofluids of water/carbon nanotubes, water/spherical silica nanoparticles and water/hybrid nanoparticles (hybrid of carbon nanotubes and spherical silica nanoparticles) have been investigated. To do so, carbon nanotubes have been synthesized by CCVD process and spherical silica nanoparticles and hybrid nanoparticles by wet chemical method. After synthesis of nanomaterials, nanofluids have been prepared by using SDBS as a dispersant with the concentration of 1.5 times of concentration of nanomaterials and then thermal conductivity, kinematic viscosity, dynamic viscosity and density of nanofluids have been investigated. As the results show,... 

In this research UHMWPE/FUMED SILICA nanocomposites with different concentrations of nano fumed silica (0.5, 1.5, 2.5, 4.5 wt %) were prepared via in situ polymerization using a novel Bi-supported Ziegler-Natta catalytic systems. Magnesium etoxide and Fumed Silica functionalized by hydroxyl groups were used as supports of catalyst. TiCl4 accompanied by triethylaluminum constituted Ziegler-Natta catalytic system. Preparation of catalyst and polymerization were done in slurry phase under the argon atmosphere. Scanning Electron Microscopy (SEM) images also certified very good dispersion of fumed silica throughout PE matrix. Intrinsic viscosity measurements showed high molecular weight for... 

The aim of this work is fabrication of magnetite@silica@gold particles. Study of the effect of pH showed that increasing pH from 9 to 12 resulted in a decrease in the size of magnetite nanoparticles from 7.9±1.38 nm to 5±0.64 nm. The TEM results indicated that modifying magnetic nanoparticles with sodium citrate prior to coating with silica leads to a narrow particle size distribution (275±16.1nm) and less number of silica nanoparticles without any magnetite core. Three methods were applied for attachment of gold nanoparticles seeds onto the silica surface: 1) use of an electrostatic interaction between positively-charged aminated silica and negatively-charged gold nanoparticles surfaces, 2)... 

Blending can be used as one of the ways of producing materials with appropriate properties, which have many relative advantages in comparison with other methods like polymerization. Among the existing blends in the market and scientific areas, blends of polyurethane thermoplastic and polypropylene have been also studied because of its commercial importance and scientific interest. This blending can improve the mechanical properties, friction resistance, improvement of impact strength at low temperatures and improvement of plasticity properties. In this research, blends with different ratios of TPU/PP is produced by melt mixing, and for improving properties of blends, two kinds of nano fumed ...