Sharif Digital Repository

The good performance in cooling, especially in systems with small dimensions, is one of the critical needs of many industries. Heat transfer around sphere in all systems that contain particles, is important. Many methods have been proposed to improve the heat transfer rate but using nanofluids is one of the ways that has attracted more attention than others. Ferrofluids have magnetic properties in addition to nanofluids properties and this has a significant impact in increasing the heat transfer rate. Controlling heat transfer by magnetic field is one of the unique characteristics of this fluid. The project aim is to investigate the effect of magnetic field on heat transfer around sphere in... 

In recent years, parallel to the development of industrial, the use of organic solvents and the environmental pollution caused by their increasing, more attention to remove these contaminants growing. Among the various absorbents to absorb pollutants from the environment, iron oxide nanoparticles have many applications in absorption and removal of environmental pollutions due to their high specific surface area, magnetic properties and ease of separation. The aim of this research is synthesis of a magnetic gel for absorption of organic solvents which in its structure magnetic nanoparticle and hydrophobic monomer is used. The most important advantages are the ease of isolation of the desired... 

Magnetite (Fe3O4) nanoparticles were synthesized and coated with Oleic Acid using the co-precipitation method. The particles were characterized using DLS, FT-IR, SEM, XRD, VSM and UV-Vis spectrophotometry analysis. The mean size of particles was 28.8 nm and the FT-IR analysis indicated that Oleic Acid was coated suitably on the nanoparticles. The vsm test indicated no hysteresis loop for the particles, defining the superparamagnetism of them. A nanofluid containing nanoparticles in 5wt% Acetic Acid in Toluene as the base fliud was prepared. The stability of this nanofluid was determined using UV-Vis spectrophotometry to be less more then 95% in the first two hours. This nanofluid is used as... 

In this thesis, heterogenous catalysts based on poly(ionic liquids) were synthesized. These catalysts were prepared by polymerization of functionalized ionic liquid monomers in the presence of an ionic cross-linker. Several types of poly(ionic liquids) such as acidic ionic liquid, basic ionic liquid and their complexs with copper and palladium were prepared. Some of these polymers were coated onto the magnetic nanoparticles to produce a catalyst with magnetic prppertise with easy magnetic separation from the reaction medium. Such catalysts have high loading level and high thermal stability. Most of prepared catalysts have high loading level due to the macromolecular nature of polymer. At the... 

Maghemite (γ-Fe2O3) nanoparticles were produced after high temperature oxidation of gelatin-Fe3O4 nanocomposite, obtained from a common coprecipitation process of Fe2+ and Fe3+ ions in an alkaline medium in the presence of a gelatin protein as an effective mediator. Size, shape, surface morphology and magnetic properties of the prepared γ-Fe2O3 nanoparticles were characterized using XRD, FTIR, TEM, SEM and VSM data. The results revealed that primary, gelatin-Fe3O4 nanocomposite had been formed and next, the gelatin decomposition in furnace produced a spinel structure of γ-Fe2O3. The effects of furnace temperature and time of heating together with the amount of gelatin on the produced... 

Nanoparticles have attracted the attention of many researchers because of the distinct physical and chemical properties. Besides the traditional applications in plastic reinforcement, fluid rheological additive, etc., the nanoparticles could be applied to many new fields and high-functional devices. Various chemical methods have been employed for the production of nanoparticles with narrow size distribution, such as co-precipitation, micro-emulsion, electrochemical synthesis, hydrothermal synthesis, sol–gel processing, flame spray pyrolysis, plasma chemical vapor deposition (CVD), hot-soap method and electrospray pyrolysis. But most of them have some problems so that only a few of them... 

Oxidation reactions in organic chemistry were applied as one of the most important methods to change the functional groups to desired one. Oxidation of alcohols to aldehydes or oxidative coupling of thiols to disulfids is two well-known examples of these conversions. The mention reactions are using commonly because of availability and simple synthesis of the alcohols and thiols. Recently the application of immobilized reagents in solid surfaces is increased because of environmental advantages.
In this study, The 1,4-diazabicyclo[2.2.2] octane (DABCO) tribromide was immobilized on two different supports by employing 3-chloropropyltrimethoxy silane: Silica Support (SS), and Nanoparticles... 

In this study the effect of nanoparticles on the mass transfer of dispersed phase in the liquid-liquid extraction systems, containing toluene with acetic acid as dispersed phase and saturated water of toluene as continues phase was investigated. For the ease of dispersion of nanoparticles in nonpolar organic dispersed phase, with the use of a novel method, hydrophobic tiania nanoparticles were synthesized and during producing with the sole-gel method were modified by adding Tetraethyl Ortho titanate as modifying agent, also the smallest hydrophobic nanoparticles of magnetite were synthesized by co-precipitating method and then, under optimum thermal condition were coated by adding Oleic... 

In this thesis, heterogenous catalysts based on magnetic nanoparticles were synthesized. In these catalysts, magnetic nanoparticles were coated with defferent fuctional groups to produce a catalyst with magnetic properties which is easily separated from the reaction medium. The structure of synthesized catalyst was characterized using techniques such as transmission electron microscopy (TEM), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and CHNS elemental analysis. Easy preparation, low cost, biodegradability and high thermal stability are advantages of these catalysts. At the end, the catalytic properties of resulted catalysts were investigated in many... 

One of the most challengeable topic in the field of green chemistry is the synthesis of organic structure in water. In this project immobilized glucose on Fe3O4 was prepared as a nano heterogeneous dispersive catalyst in water. The catalyst was fully characterized by FT-IR, TGA, CHN, SEM, EDX and atomic absorption spectroscopy. The synthesized catalyst was used in the synthesis of different derivatives of 1,2,3-triazole via one-pot three component reaction of alkynes, alkyl halides, sodium azides; And to the best of our knowledge this novel catalyst coin sides to the principles of green chemistry. This nano catalyst can be recycled and reused for several runs without significant loss of its... 

In this project, Fe3O4 nanoparticles were synthesized and coated with different polymeric materials for drug delivery application. For this purpose, water dispersible oleic acid(OA)- pluronic block copolymer coated magnetite iron oxide nanoparticles were synthesized that can be loaded with proper doses of cephalexin. Our data indicated that formulation of iron oxide nanoparticles was developed by optimizing the amount of oleic acid required to coat iron oxide nanoparticles and then by optimizing the amount of pluronic required to form an aqueous dispersion of oleic acid coated nanoparticles. Synthesis of magnetite nanoparticles was done by the addition of a strong base (NH4OH) to ferrous... 

Lately, a wide application of eco-friendly polysaccharide-based hydrogels in waste water treatment has received enormous attention in the literature. The effluents containing dye materials from the processing industries are washed off into rivers and lakes which can be very harmful to creatures. Low-cost biopolymers and biodegradable adsorbents have been researched to be a good tool to minimize the environmental hazards caused by the industrial effluents by removal of these toxic and carcinogenic dyes from the waste effluents. In this study, an eco-friendly superabsorbent hydrogel was prepared by using of sugarcane bagasse, two hydrophilic monomers, magnetic nanoparticle and methylene... 

Removal of petroleum hydrocarbons from water is one of the environmental challenges. In this study the functionalized magnetic nanoparticles (MNPs) was used to remove kerosene oil as contaminants from water. Effective factors on adsorption of oil on MNPs were investigated. Magnetic nanoparticles were synthesized on activated carbon derived from almond shell and after a coating by silica, it Was functionalized by NH2 and COOH functional groups. After preparation of kerosene oil/water stable emulsions by emulsifier, the adsorption capacity of AC@Fe3O4@SiO2-NH2-COOH was evaluated. The adsorbent was characterized by various physicochemical techniques such as transmission electron microscopy,... 

Our goal in this research is to fabricate janus micromotors capable of moving in aquious media and being manipulated by an external magnetic field. Such devices were made via attaching magnetic nanoparticles to the surface of magnesium janus motor. The FTIR study proved their existance and physical attraction to the surface of the motors. They were easily navigated through a static magnetic field and janus motors aligned their motion to the direction of magnetic field. The anisotropic geometry of janus micromotors were verified through scaning electron microscope and elemental analysis. Biocompatibility of magnetised janus motors were examined through mtt assay and it was shown that the... 

The present study is aimed at the development of a novel approach based on the magnetically improvement of DNA-directed immobilization to prepare a highly efficient sensor for prostate diagnosis. The novelty of this work is in the use of antibody conjugated magnetic nanoparticles via DDI. DNA-modified magnetic nanoparticles are added in solution to capture DNA-conjugated, fluorescently-labeled immunocomplexes formed in solution free of steric constraints. The DDI-based nanoconstructs are then concentrated and immobilized using a magnetic field. Compared to a process in which the immunocomplex directly forms on the sensing surface, the proposed approach provides higher mass transfer and lower... 

The process of separating cells from a laboratory sample, is a crucial step in biotechnology and medical science. Cells separation is important for various reasons, including the identification and treatment of diseases, as an example, separation of Circulating Tumor Cells (CTCs) from patient blood sample. CTCs are cells that shed from a tumor and diffuse into blood vessels. These cells are the starters of metastasis, the process in which cancer spreads in body, and are main reason of deaths caused by cancer. Extremely low percentages of target cells in the blood, clarify the importance of highly accurate and sensitive separation. Currently, conventional separation methods are of macro-order... 

In the present thesis, the adsorption ability of the functionalized magnetic nano-particles supported on the walnut and almond based activated carbons was evaluated to prepare the efficient and low cost adsorbents for removal of Pb(II), Cr(VI) and Hg(II) ions aqueous solutions in the presence of salinity. The activated carbons were derived from almond and walnut shell by the physical activation method. The functionalized nano-magnetic activated carbons were synthesized by co-precipitation consisting of AC(almond)@Fe3O4@SiO2-NH2-COOH and AC(walnut)@Fe3O4-NH2-COOH which were modified by the oxygen containing functional groups to enhance the adsorption capacity. The prepared carbonaceous... 

In this thesis, heterogenous catalysts based on magnetic nanoparticles coated with organosilanes and poly(ionic liquids) were synthesized. These catalysts were synthesized by hydrolysis of tetraethyl organosilanes and other organosilicons such as 3-aminopropyl triethoxy silane and polymerization of some monomers in the presence of ionic cross-link agents. The synthesized matrixes were used to stabilize precious metals such as Pd and Au. The magnetic properties of the catalysts aid to easy separation from the reaction medium by an external magnetic field. High thermal stability low toxicity and high-level loading of metals are some beneficiaries of the magnetic catalysts. At the end,... 

In this thesis, it reports the fabrication of novel magnetic nanocomposites combining the unique properties of magnetic nanoparticles and cross-linked basic polymers that their surface functionalized by suitable groups such as carboxylate groups, pentaethylenehexamine and so on to achieve the maximum adsorption capacity of dyes and heavy metal ions. The performance of the magnetic nanocomposites for removal of anionic and cationic dyes and heavy metal ions were evaluated in different conditions of pH, contact time and initial concentrations. Moreover, the adsorption mechanism was investigated by kinetic models and isotherm studies. The results showed that the abovementioned adsorbents can... 

The main strategy for treating solid cancers is based on the very early diagnosis of a malignant tumor, and in general the smaller the tumor, the greater the likelihood of successful treatment. Magnetic Resonance Imaging (MRI), based on the nuclear magnetic resonance phenomenon, provides the possibility of detecting early malignant tumors with the assistance of appropriate contrast agents. Hence, researchers continue to develop novel magnetic materials to achieve this aim. Superparamagnetic nanoparticles have become the focus of these studies because their superparamagnetic, biocompatible and hydrophilic properties would be revealed after modifying the particle surface by suitable...