Sharif Digital Repository

Dissolution pressure and nozzle temperature effects on particle size and distribution were investigated for RESS (Rapid Expansion of Supercritical Solution) process. Supercritical CO2 was used as solvent and Ibuprofen was applied as the model component in all runs. The resulting Ibuprofen nano-particles (about 50 nm in optimized runs) were analyzed by SEM and laser diffraction particle size analyzer systems. Results show that in low supercritical pressure ranges, depending on the solvent and solid component properties (Lower than 105 bar for Ibuprofen-CO2 system), nozzle temperature should be as low as possible (80-90 °C for Ibuprofen-CO2 system). In the other hand in high supercritical... 

The aim of this research was to synthesize barium sulfate nanoparticles using a spinning disk reactor. Barium sulfate was produced by continuously pumping two aqueous solutions of BaCl2 and Na2SO 4, respectively, into the chamber of spinning disk reactor, where a liquid-liquid reaction took place to form BaSO4. The influences of various operating and design parameters such as the initial supersaturation, disk rotation speed, free ion ratio, and the disk diameter on the size of barium sulfate nanoparticles were carefully investigated. By varying the supersaturation and disk rotation speed, a broad range of particle size ranging from micrometer sizes down to nanoparticles smaller than 100 nm... 

Glycerol might be converted into hydrogen through a catalytic reforming process. In order to design an effective route, the choice of reaction conditions and in particular its medium considered yet a crucial issue still needing further investigations. In this research, a mathematical model of reforming processes in vapor (i.e., steam reforming (SR) and liquid phase (i.e.; aqueous phase reforming (APR)) were developed. This was performed in terms of understudying effects of parameters including the reactor diameter, catalyst morphology (i.e., particle size) and mass flow rate on the glycerol conversion. Then, a superior reaction medium in terms of these variables was determined. For data... 

Nanocomposites of Ce-TZP/Al 2O 3 were synthesized by aqueous combustion, and urea, ammonium acetate and glycine were used as mixtures of fuels with the corresponding metal nitrates. Thermodynamic modeling was conducted to anticipate the effect of the alumina content on the exothermicity of the combustion procedure. The thermodynamic properties of the combustion reaction indicated that as the alumina content increased, the amount of gases produced during the reaction increased with a decrease in the adiabatic temperature. Furthermore, to reduce the particle size of the powders, a series of combustion reactions were performed to optimize the fuel composition and alumina content. Ce 0.1Zr 0.9O... 

Magnetite nanoparticles (mean particle size ranging from 10 to 20 nm) were prepared by a biomoleculeassisted solution-phase approach under ultrasonic irradiation. Cysteine was used as the capping agent in the solution. The results show that cysteine could be an efficient biocapping agent in producing Fe3O4 nanoparticles. The crystal structure and magnetic properties of the nanoparticles were characterized by XRD and VSM techniques, respectively. FT-IR was used to investigate the presence of cysteine on the nanoparticles surface. The influence of pH value of the solution on the size distribution and hydrodynamic size of nanoparticles were studied by TEM and DLS methods, respectively. The MTT... 

We report the rheological properties of ferro-fluid (FF) containing iron oxide nano-particles. At first, a FF was synthesized by using chemical co-precipitaton[1]. The microstructure study using SEM revealed that the FF contained nano-particles with the mean particle size of 35nm. The XRD study revealed that we have well crystallized structures of magnetite; they appeared to be approximately single crystalline structures. The rheological results proved that the FF has non Newtonian behavior, it is a shear thinning fluid in all magnetic fields, Moreover, the magnetic field increases the viscosity in a definite shear rate due to the nano-particles agglomerations and formation of chain-like... 

A new high-speed spinning disk reactor (HSSDR) was proposed and tested successfully. In this regard, barium sulfate (BaSO4) nanoparticles were synthesized using reactive crystallization processes. In this reactor, the rotational disk speed was varied from 5000 to 15 000 rpm. The effects of various design and operating parameters such as the rotational disk speed, feed entrance radius, volumetric flow rate of feed solutions, supersaturation, and free ion ratio were investigated in detail. The mean particle size (MPS) and specifications of the synthesized barium sulfate were investigated using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy and powder X-ray... 

In this article, a confined-impinging-jets reactor (CIJR) was designed and tested successfully for the synthesis of calcium carbonate nanoparticles using the reactive precipitation method. The proposed CIJR comprised of two opposed nozzles placed in a cylindrical chamber. Effects of various operating and design parameters such as supersaturation, feed flow rate, nozzle diameter, reactor diameter, operating temperature, and surface-active agents on the mean particle size, particle size distribution, and the polymorphs of calcium carbonate nanoparticles were investigated carefully. By changing the supersaturation, reactor diameter, jets velocity, operating temperature, and the nozzle diameter,... 

In this article, a confined-impinging-jets reactor (CIJR) was designed and tested successfully for the synthesis of calcium carbonate nanoparticles using the reactive precipitation method. The proposed CIJR comprised of two opposed nozzles placed in a cylindrical chamber. Effects of various operating and design parameters such as supersaturation, feed flow rate, nozzle diameter, reactor diameter, operating temperature, and surface-active agents on the mean particle size, particle size distribution, and the polymorphs of calcium carbonate nanoparticles were investigated carefully. By changing the supersaturation, reactor diameter, jets velocity, operating temperature, and the nozzle diameter,... 

In this article, a confined-impinging-jets reactor (CIJR) was designed and tested successfully for the synthesis of calcium carbonate nanoparticles using the reactive precipitation method. The proposed CIJR comprised of two opposed nozzles placed in a cylindrical chamber. Effects of various operating and design parameters such as supersaturation, feed flow rate, nozzle diameter, reactor diameter, operating temperature, and surface-active agents on the mean particle size, particle size distribution, and the polymorphs of calcium carbonate nanoparticles were investigated carefully. By changing the supersaturation, reactor diameter, jets velocity, operating temperature, and the nozzle diameter,... 

Electromagnetic levitation gas condensation (ELGC) method was used to synthesize silver nanoparticles (NPs). Silver droplets were melted and levitated stably at about 1130°C with appropriate flat coils in a 10mm OD silica tube. High purity argon, nitrogen and helium were employed as carrier gases and cooling media. Morphology and particle size of the products were investigated by scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX) and dynamic light scattering (DLS). The DLS, SEM and TEM studies demonstrated narrow size distribution of spherical shape silver NPs with mean particle size of about 60, 50 and 30nm... 

We report a simple, inexpensive and one-step synthesis route of colloidal gold nanoparticles using arc discharge between titanium electrodes in HAuCl 4 solution achieving long-time stability. Gold nanoparticles of 8 nm diameter were formed during reduction of HAuCl4 in the plasma discharge zone. The resulting nanoparticles were characterized using UV-Vis spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Optical absorption spectroscopy of as prepared samples at 15 A arc current in HAuCl4 solution shows a surface plasmon resonance around 550 nm. It was found that sodium citrate acts as a stabilizer and surface capping agent of the colloidal...