Sharif Digital Repository

There are many different opinions about the mass transfer contribution during jet formation in liquid - liquid extraction columns, and this could impact on their design. In this work, using experimental data obtained in two RDC columns and unpublished data of the jet mass transfer coefficients, mass transfer can be predicted during jet formation. The jet length and diameter were anticipated by using existing relations, and then the jet mass transfer coefficient was predicted, jet mass transfer rate and total column mass transfer rate were calculated and finally the contribution of mass transfer during jet formation in the column was predicted. Mass transfer contribution in the jet in various... 

It is well known that sulfur removal from petroleum is necessary for both industrial and environmental reasons. Sulfur in petroleum products corrodes parts of internal combustion engines and refineries due to the formation of sulfur oxyacids and causes major air pollution and acid rain due to exhaust from diesel engines and emission of sulfur oxides. Hydrodesulfurization (HDS), biodesulfurization (BDS), extraction by ionic-liquids (ILs), selective adsorption, alkylation desulfurization and oxidative desulfurization (ODS) are some methods, can be effective in removal of sulfur compounds. Among these new processes, ODS appears to be particularly promising and is currently receiving increasing... 

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... 

Purification of hydrogen, as a clean source of energy has attracted great deal of attention in recent years. Among all available H2 separation methods, membrane technology has been known as the most appropriate way to produce hydrogen with high purity. In this study, we have tried to synthesis and evaluate the performance of perovskite ceramic membranes. The aim of preparing this type of membranes is to use them in separation processes in order to achieve H2 with high purity of >99%. First, general concepts about membranes are discussed. Then synthesis, recognition and performance evaluation of some perovskite membranes are presented. To prepare membranes, ceramic powders are synthesized by... 

In this work 1-(2-hydroxyethyl)-3-methylimidazoliumbis{(trifluoromethyl) sulfonyl}imide ([hemim][NTf2]) and 1-benzyl-3-methylimidazoliumbis{(trifluoromethyl) sulfonyl}imide ([bzmim][NTf2]) ionic liquids were used to study the effect of introducing hydroxyl and benzyl groups to the imidazolium cation on aliphatic/aromatic separations. Toluene separation from heptanes has been investigated by extraction using ionic liquids. Finally, a realistic model for survey the data was used. The liquid-liquid equilibrium (LLE) data for the {heptane + toluene + [hemim][NTf2]}, {heptane + benzene + [hemim][NTf2]} , {heptane + toluene + [bzmim][NTf2]} systems were measured at 313.2 K and atmospheric... 

Volatile organic compounds are major cause of air pollution. In this work, Nano porous material named MIL-101(Fe), MIL-53(Fe), MIL-101(Fe) and MIL-88(Fe) as an adsorbent for the removal of ethyl benzene have been synthesized hydrothermally. The materials were characterized by Fourier-transform infrared (FT-IR) spectroscopy, Surface Analysis Systems (ASAP), and x-ray diffraction (XRD) analysis. Adsorption isotherms of ethyl benzene on the materials were measured experimentally in case of 0-1000ppm concentration of ethyl benzene in air and pressure 1 atmosphere. The mixture of air and VOC (ethyl benzene) with concentration of 100, 250, 500 and 1000 ppm and flow rate of 400, 1030, 1525 and 2025... 

Underground reservoirs are highly complicated due to the presence of spatial heterogeneities at length scales that span from micrometer in pore structure of the rocks to kilometer in the reservoir models. While large-scale flow units need to be characterized using seismic and well data, detailed displacements of fluids in pore space need to be modeled using thin section analysis and pore network modeling. It is therefore necessary to adopt a multi-scale approach to reservoir description to make best use of all the available data that vary over several orders of magnitude, from micro-scale in pore structure to field scale in reservoir flow models. In this thesis, an integrated framework for... 

In this research, we have tried to predict the morphology of the membranes that were prepared by phase inversion method. In this research Polyvinylinedifluoride (PVDF) and dimethylacetamide (DMAc) was used as the polymer and solvent. The affect of titanium oxide (TiO2 ) and polyvinylpyrolidene (PVP) which are respectively an inorganic and an organic additive, on the morphology of the membranes was investigated. Ternary and Quadratic phase diagrams were drawn based on the Flory Huggins theory. The interaction between components was determined and the effect of interactions and molar volumes of polymer, solvent, non-solvent and additives on the binodal line was investigated. To predict... 

In this study, In order to reduce volatile organic component (benzene, toluene, xylene and ethyl benzene) some appropriate nanostructures were used. First the appropriate nano structures were identified, then modified and optimized and finally characterized by XRD, SEM, ASAP. Appropriate nano adsorbent such as nano active carbon, single wall and multi wall nano carbon tubs , nano fiber carbon, graphene oxide, aluminum oxide particles, nano-zinc oxide , titanium oxide particles, 13x zeolite and extruded nano carbon tubes, were prepared and optimized, than evaluated from perspective of the crystal structure, surface area and porosity. nano active carbon, single wall and multi wall nano carbon... 

Adsorption of acetone vapors on mixture of silica gel and activated carbon was studied. Adsorption is defined as the attraction adsorbate (liquid or gas) particles onto the surface of a solid (porous solid). Most of the experimental works are adsorption of a one or more component on an adsorbent. Presence of two or more adsorbents together may effect on adsorption rate, uptake and thermodynamic conditions. When we have limitation in using a kind of adsorbent, these results can be helpful. There are several motivating reasons for the study of adsorption on adsorbent mixtures. During the adsorbent manufacturing process, multiple batches may differ slightly from each other(and from the customer... 

In this work, we have tried to synthesize, recognize and evaluate the performance of a composite ceramic membrane to purify hydrogen and obtain high H2 separation values from other gases such as methane, carbon dioxide and nitrogen at high operating temperatures (837- 1073 K). The membrane was prepared by modification of a tubular alpha- alumina support with a series of gamma- alumina layers using sol- gel method. The membrane was then covered with a Nano-composite silica- alumina layer using CVD method. The thickness of this layer is estimated to be around 80- 100 nm and with a completely dense structure. EDX, XRD, DLS, BET and mercury porosietery analysis plus SEM and FESEM images were... 

Natural gas contains small amount of benzene, toluene, ethyl benzene and meta-xylene (BTEX). These compounds are soluble in amine solutions and accumulate in aqueous amine solution during sour gas removal process. They produce problems such as foaming in amine adsorption columns. The aim of this work is to study BTEX removal from aqueous amine solution by means of activated carbon. Three different commercially available granular activated carbons were used in experiments. Experiments were divided in static and dynamic adsorption categories. In the static tests, equilibrium adsorption of all three activated carbons were performed and the most effective activated carbon sample determined by... 

A Microbial fuel cell is a Bioreactor in which chemical bands are broken and their energy convert to electricity by bio-catalysts such as microorganisms and enzymes. Depletion of energy resources encouraged researchers to investigate microbial fuel cell as a power bio-resource. MFCs produce electricity or hydrogen without any net carbon emission. Nowadays, real applications of microbial fuel cells are limited because their power density level is very low (about 1000 mW/m2). Many research projects are running to modify MFCs operation and optimize its costs. The most important application of MFCs is electricity production, hydrogen production, waste water treatment and BOD5 biosensor. In this... 

Celery residue modified with H2SO4 was utilized as a low-cost adsorbent for removal of hazardous dyes (methylene blue, malachite green and congo red) and heavy metals (Pb(II) and Cd(II)) from aqueous solution in batch adsorption process. Also, celery residue modified with cationic surfactant (CTAB) to enhance the removal of congo red (anionic dye). The treated and untreated adsorbent was characterized by Fourier transform infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM). The efficacy of dye removal of the modified celery residue was investigated by varying adsorbent dose, contact time, pH, initial dye concentration, and temperature. Experimental data were fitted by three... 

In this work, the segregation of solids in 2D gas-solid fluidized beds has been investigated carefully doing DPM approach. In this regard, various types of mixing index reported in the literature were need. Lacey index was chosen to study to study the segregation for different conditions. Effects of jetsam concentration, bed aspect ratio, solids density, restitution coefficient, initial arrangement and operation pressure and temperature were investigated. It was found that for beds with the mixed initial conditions, with an increase in the superficial gas velocity, the mixing index decreases and then increases. In addition, the mixing index increases with an increase in the jetsam... 

Conjugation of proteins to nanoparticles has numerous applications in sensing, imaging, delivery, catalysis, therapy and control of protein structure and activity. Therefore, characterizing the nanoparticle–protein interface is of great importance. A variety of covalent and non-covalent linking chemistries have been reported for nanoparticle attachment. Typically, a specific protein residue is linked directly to the nanoparticle core or to the ligand. As conjugation often affects the protein structure and function, techniques to probe structure and activity are assessed Characterization studies of nanoparticle–protein complexes show that the structure and function are influenced by the... 

The main objective of the present work was to improve the turbulence in single drops using ferrofluids (magnetic nanoparticles) in the presence of uniform and oscillating magnetic fields. In this regard, magnetite nanoparticles ($\mathrm{Fe_3O_4}$) were synthesized by co-precipitation method, characterized using DLS, FT-IR, XRD, VSM, and TEM, and their stability was checked by UV-Vis. The obtained results indicate the proper synthesis of nanoparticles with a mean diameter of about 20 nm and by coating their surfaces by silane that were well stabilized in the base fluid. In the numerical section, the governing equations of transport phenomena for a single drop containing magnetic fluids were... 

Titanium alloy Ti-6Al-4V ELI with high biocompatibility and corrosion resistance, has a lot of applications in biomedical engineering. Disadvantage of this alloy is it’s disability to create a fast and good contact with the host/bone environment, after implanting in the body. Beside that it has low wear resistance. Nowadays to optimize the wear resistance, bioactivity and osteoconduction of surface of implants which are made from this alloy, the surface morphology are optimized in size and distribution. Different surface treatments are used for producing rough and porous surfaces to improve bioactivity along with wear resistance. In this study, surface modification of Ti-6Al-4V ELI was done... 

Commercially pure titanium (CP-Ti) is an important groups of titanium family and because of high strength, low density, high corrosion resistance and biocompatibility, this group of titanium is a suitable choice for application at chemical, petrochemical and medicine industry. Nowadays surgeons have a tendency toward use of CP-Ti instead of Ti-6Al-4V alloy. Moreover, because of body anatomy limitation, use of thick sheets result in high volume and damage soft tissue. Therefore, for sheet thickness reduction, study of the effects of metallurgical and geometrical parameter on fracture behavior of thin sheets is important. In this study, the fracture behavior of CP-Ti thin sheets investigated.... 

AISI 4340 steel bars were austenitized at 900°C for 1 hour followed by heating at 740°C (ferrite and austenite region) for 100 min and quenching into a salt bath at 300°C for different times followed by quenching into water to obtain triple phase microstructures with 34 Vol.% ferrite and various martensite (or bainite) contents. Presence of three phases in adjacent of each other confirmed by metallographic analysis and TEM technique. Volume fraction of different phases was measured by image analyser. The results of optical microscopy showed that by increasing VM, morphology of martensite varies from uniform distribution of small spherical network particles to large blocky islands with...