Sharif Digital Repository

Asphaltene which cover range of 1% to over 10% of oil by weight, is well-known as most problematic part of oil that can deposit during production in reservoir, well tubing, and surface production lines, and consequently impose a serious restriction on production which in turn increases total cost of entire operation. Through decades an extensive research has been performed in order to identify asphaltene molecular structure, its behavior at different condition, and its separation mechanism from oil. One of most critical parameter associated with asphaltene precipitation modeling is flocculated asphaltene weight percentage in oil at given operation condition. In this study, to eliminate cost... 

In this study, the effects of CeO2 nanoparticle addition on tensile strength and formation of interfacial intermetallic compound layer for lead-free Sn-3.5Ag-0.7Cu solder joint were investigated. The results showed that the thickness of intermetallic layer was decreased with increasing weight percentages of CeO2 reinforcements, and the growth of the intermetallic layer was remarkably suppressed during isothermal aging at 150 C. It was also found that the tensile strength of the solder joint gradually increased with the addition of CeO2 particles, reached to the maximum value at 0.5 wt% CeO2 and then decreased drastically with further increase in CeO2 content. Microstructural investigation of... 

A novel heterogeneous copper catalyst was synthesized in which poly(1-vinyl imidazole-co-ionic liquid) was used as a solid heterogeneous support. The catalyst was readily synthesized in a large scale amount. The catalyst has a high loading level of copper ions and can be used in low weight percentages. The resulting catalyst was highly active in the preparation of triazoles by the Huisgen 1,3-dipolar cycloaddition method. In some cases the catalytic turnover number and frequency reached 70 002 and 3889 h-1, respectively. The catalyst was recycled many times without significant loss of activity. This journal is  

A simple method for synthesis of novel organogels based on multiwalled carbon nanotubes (MWCNTs) is reported. Three classes of organogels were synthesized by crosslinking polymerization of dodecyl methacrylate with various weight percentages of 1,4-butanediol dimethacrylate, vinyl-group-modified MWCNTs or pristine MWCNTs in the presence of 2,2-azoisobutyronitrile as initiator. In this reaction, the carbon nanotubes (CNTs) served simultaneously as an adsorbent, a comonomer and a crosslinking agent. The oil-absorbent containing CNTs showed much higher swelling capacity in oil and organic solvents compared with that without CNTs. Therefore, CNT-based organogels can be introduced as a promising... 

Experiments were conducted to investigate the effect of adding fines on the tribo-charging of coarse glass beads. Four types of fines, i.e., copper, stainless steel, uncoated and silver-coated fine glass beads, mixed with 240–830 μm glass beads were conveyed by air through a stainless-steel spiral pipe acting as a tribo-charger. Regardless of the type or electrical conductivity of the fine particles tested, adding small amounts of fines (up to 10 wt%) to coarse glass beads resulted in a sharp increase in the mass and surface charge densities of the particles. In general, the profiles of the mass and surface charge densities of the fine–coarse particle mixtures as a function of the mixture... 

Industrial-scale production of aromatic materials is confronted by the problem of removal of impurities such as olefins. Their removal is an essential requirement in marketability. Catalytic adsorbent clay is the most common material used for the removal of olefins from aromatic streams. The current study is focused on increasing the lifetime of a commercial type of clay by identifying the effective parameters in reducing the adsorbent lifetime. An analysis of 3 years of data from a petrochemical complex showed that water, morpholine, and N-formyl morpholine (NFM) contents in the feed stream are the factors reducing the clay lifetime. Various experiments have been performed to determine the... 

This article reports the first oil-absorbent cross-linked copolymer consisting of modified multiwalled carbon nanotube (MWCNT) and showing high oil absorbency. Also, to investigate and evaluate the effective parameters on oil absorbency, cross-linked dodecyl methacrylate (DDMA)-diphenylacrylamide (DPAA) and DDMA-butyl acrylate (BA) copolymers were synthesized. DDMA was copolymerized with different mol% of DPAA or BA and cross-linked using azobisisobutyronitrile as the initiator and various weight percentages of 1,4-butandiol dimethacrylate, methylene bisacrylamide, or vinyl group-modified MWCNT cross-linkers. The effects of monomer feed composition, cross-linker concentration, and the... 

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,... 

In the present study, the hybrid reinforcements (Fe3O4–SiC) novel composite has been successfully fabricated by powder metallurgy method. Adding Fe3O4 nanoparticles and SiC hybrid reinforcements in the aluminium matrix, improved the magnetic permeability of aluminium matrix composites as well as, thermal properties without mechanical degradation. In this study, the aim was to define the influence of SiC–Fe3O4 nanoparticles on microstructural, thermal, electrical, and magnetic properties of the composite. Based on obtained results, the highest density and hardness is 2.72 g/cm3 and 93 HV respectively. Adding (10–30 wt% SiC) into Al–15Fe3O4 slightly improved the magnetic saturation from... 

An investigation into the addition of different weight percentages of Fe3O4 nanoparticles to find the optimum wt.% and its effect on the microstructure, thermal, magnetic, and electrical properties of aluminum matrix composite was conducted using the powder metallurgy method. The purpose of this research was to develop magnetic properties in aluminum. Based on the obtained results, the value of density, hardness, and saturation magnetization (Ms) from 2.33 g/cm3, 43 HV and 2.49 emu/g for Al-10 Fe3O4 reached a maximum value of 3.29 g/cm3, 47 HV and 13.06 emu/g for the Al-35 Fe3O4 which showed an improvement of 41.2%, 9.3%, and 424.5%, respectively. The maximum and minimum coercivity (Hc) was... 

To improve the biocompatibility and corrosion resistance of 316L SS (Stainless Steel) metal implants, HAp(hydroxyapatite)/TiO2/Al2O3 nanocomposite coating was created using dip sol-gel method sintered at 550 °C. The weight percentage of TiO2+ Al2O3 in these coatings was 20, 30, and 40% wt. In this study, characterization was performed using FTIR (Fourier-Transform Infrared Spectroscopy), XRD, FE-SEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), DLS (Dynamic Light Scattering), Pull-off, and AFM (Atomic Force Microscopy) analysis. The potentiodynamic polarization and EIS (Electrochemical Impedance Spectroscopy) were performed in the simulated body fluid... 

To improve the biocompatibility and corrosion resistance of 316L SS (Stainless Steel) metal implants, HAp(hydroxyapatite)/TiO2/Al2O3 nanocomposite coating was created using dip sol-gel method sintered at 550 °C. The weight percentage of TiO2+ Al2O3 in these coatings was 20, 30, and 40% wt. In this study, characterization was performed using FTIR (Fourier-Transform Infrared Spectroscopy), XRD, FE-SEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), DLS (Dynamic Light Scattering), Pull-off, and AFM (Atomic Force Microscopy) analysis. The potentiodynamic polarization and EIS (Electrochemical Impedance Spectroscopy) were performed in the simulated body fluid... 

In the present research, the introduction of multi-walled carbon nanotubes (MWCNTs) into the hydroxyapatite (HA) matrix and dip coating of nanocomposite on titanium alloy (Ti-6Al-4V) plate was conducted in order to improve the performance of the HA-coated implant via the sol-gel method. The structural characterization and electron microscopy results confirmed well crystallized HA-MWCNT coating and homogenous dispersion of carbon nanotubes in the ceramic matrix at temperatures as low as 500 C. The evaluation of the mechanical properties of HA and HA/MWCNT composite coatings with different weight percentages of MWCNTs showed that the addition of low concentrations of MWCNTs (0.5 and 1 wt.%)... 

To improve the biocompatibility and corrosion resistance of 316L SS (Stainless Steel) metal implants, HAp(hydroxyapatite)/TiO2/Al2O3 nanocomposite coating was created using dip sol-gel method sintered at 550 °C. The weight percentage of TiO2+ Al2O3 in these coatings was 20, 30, and 40% wt. In this study, characterization was performed using FTIR (Fourier-Transform Infrared Spectroscopy), XRD, FE-SEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), DLS (Dynamic Light Scattering), Pull-off, and AFM (Atomic Force Microscopy) analysis. The potentiodynamic polarization and EIS (Electrochemical Impedance Spectroscopy) were performed in the simulated body fluid...