Sharif Digital Repository

In this work ionic liquids as the new generation of solvents are studied. First, Ionic liquids are introduced and their applications and characteristics are briefly discussed. Then, one of the most potential applications of ionic liquids in separation process (Aromatic-Aliphatic separation) is studied and compared with the common and alterative separation processes. In experimental section, large amount of 1--ethyl 3-metyl pyridinium ethyl sulphate ionic liquid was synthesized with a purity of above 99%. Experimental studies of separation of toluene from its mixture with n-heptane with the aid of synthesized ionic liquid were conducted and acceptable results are obtained. Experimental LLE... 

Using membrane contactors for acid gas removal, combines the advantages of membrane based separation processes and traditional ones. In this project we aim to study the use of a membrane absorption system for sweetening gas streams containing mixed acid gases with composition similar to raw natural gas. H2S and CO2 exist in the gas stream simultaneously which can be removed by mixture of alkanolamine solvents, including MDEA, DEA and MEA, are used for treating. A lab-scale membrane absorption setup with feed capacity of 2 lit/min, was designed, constructed and commissioned. Several hollow fiber modules equipped with PSf and PVDF membranes were fabricated. Our results revealed that reaching... 

Separation of biomolecules such as enzymes is the most important part of biotechnology process which 10-90 % of costs is for separation and purification. There are several methods for purification of bio materials and one of them is chromatography which use in enzyme purification but this method have several problem such as cost ,time consuming and scale up Because of this a suitable alternative demands for industrial separation. An alternative is aqueous two-phase systems (ATPS). In this project was studied about partial purification of alkaline protease produced by Bacillus licheniformis ATCC 21424 in aqueous two-phase system and comparison with chromatography method. an aqueous two-phase... 

Supported ionic liquid membranes are prepared by filling the pores of a porous membrane with ionic liquids. Permeability values of carbon dioxide and methane and also selectivity value of CO2⁄CH4 through ionic liquids stabilized on porous alumina membrane supports have been experimentally investigated. We have used [hmim][Tf2N] and two synthesized ionic liquids, 1,6-Di(3-methylimidazolium)hexane bis(trifluoromethylsulfonyl)imide (h[mim]2[Tf2N]2) and 1,3-Di(3-methylimidazolium)propane bis(trifluoromethylsulfonyl)imide (pr[mim]2[Tf2N]2) in our research. The experiments have been done in the temperature range of 27–45 ℃ and pressures of 10–50 kPa and the impact of the temperature and pressure... 

In the recent decades, Polymer Electrolyte Membrane Fuel Cells (PEFC) have been known as an appropriate type of fuel cells, due to being electrochemical converter and clean energy generator with high power density and having low operation temperature and launch time. Palatine is one of the major materials that are used in electro-catalysts of fuel cell. Due to shortage of palatine resources and its high price, fuel cell production is not economical. To achieve economic conditions for production of fuel cell, two major methods are proposed:
1) Reduction of the employed amount of palatine in electro-catalyst
2) Full replacement of palatine with cheap materials
In the current... 

Due to increasing environmental concern, special interest has been paid to reduction of organosulfur compounds in transportaion fuels. The sulfur- containing compounds are converted into sulfur oxide, i.e, SOx , during combustion, which is a major source of acid rain and air pollution.Gas condensate is a mixture consisting primarily of pentanes and heavier hydrocarbons which is recovered as a liquid from natural gas. It is a proper hydrocarbon source for producing gasoline, kerosene and gas oil in refineries. In this reseach a gas condensate was used as feedstock for studing oxidative desulfurization (ODS). The influence of various parameters of desulforization including the reaction... 

In recent years membrane bioreactors (MBR) were widely used as an advanced process for industrial wastewater treatment. But fouling issue causes some restrictions in these systems. So for fouling reduction many researches were done.In this study for fouling improvement, blending of hydrophilic polymer (PAN) with main polymer PVDF was used. Blending membrane in phase inversion process with DMAC as solvent and water as non-solvent was made. For pore-forming in membranes, PVP as hydrophilic additive with three different composition was added and then for more enhancement of antifouling property of membrane, TiO2 nanoparticles with four different composition were added to polymeric... 

In the presence project by using of hydrophilic polymer, Cellulose acetate (CA), we tried to modify the membrane made of Polyvinylidine fluoride (PVDF). The membranes were made by phase inversion method. In five levels, at least 10% and at most 30%, CA was added to casting solution. The hydrophilicity of membranes’ surface and pore size was increased. The permeation of the neat membrane of PVDF was less than 10 , on the other hand the permeation of the membranes, which were made by adding CA, was increased up to 500 . The increment of CA more than 20% reduced the porosity of membrane. In the next step to reduce the irreversibility fouling tried to reduce the pore size by adding some... 

Hydroxyurea is an anticancer drug that is commonly used to treat chronic myeloid leukemia (white blood cell cancer in bone marrow), polycythemia vera (red blood cell cancer), sickle cell anemia, solid tumors, and in particular leukemia. In this research, in addition to analyzing all available methods for synthesis of hydroxyurea, the most economical method for synthesis of hydroxyurea which is Hantzsch method was chosen; then we synthesized hydroxyurea crystals using a precipitation or crystallization process. To do so, two hydroxylamine hydrochloride and potassium cyanate reactants have been used in the semi batch reactor. Since the reaction efficiency and purity of the synthesized... 

The Visbreaking process is one of the Residue upgrading method, which, in addition to the production of mid-distillate products, also reduces the viscosity of feed. By reducing the viscosity of the feed, the amount of cutter stock is reduced to produce fuel oil. Since the refiners want to achieve the maximum conversion in the visbreaker unit, it is necessary to estimate the proper operating conditions and distribution of the products. Increasing in conversion in a visbreaker unit will lead to a refinancing profit. In this work, four Vacuum Residual oil from Iranian Refineries were selected for studying on visbreaking process. Experiments were carried out at RIPI-Petroleum Refining Technology... 

In recent years, the reductive dehalogenation of the chlorinated hydrocarbons using nanoscale zerovalent iron (nZVI) represents a promising approach for underground remediation. Regarding commercialization of this technique, instability and unknown nature of nZVI particle are still challenging tasks that should be considered.
In the current work, Nanoscale zero-valent iron (nZVI) and palladized iron (Pd/Fe) bimetallic particles were synthesized and employed to react with chlorinated compound (PCE) in water to investigate its degradation behaviors. The results show that the reactant ratio, stabilizer amount and temperature are the main parameters with the considerable effect on PCE... 

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... 

The introduction of multi phase steels in recent years resulted in a considerable increase in development of some industries such as automobiles. By inducing soft and hard phases together, these steels could bring better mechanical properties than classical ones. Recent studies on 4340 ferritic- bainitic and ferritic- martensitic dual phase steels, indicate that 34 volume percent ferrite with hard phase, has the best combination of strength, toughness and fatigue properties. In present research, by proper heat treatment on a 4340 steel, it is tried to prepare specimens ferritic- bainitic- martensitic triple phase steels with 34 volume percent of ferrite and different percents of martensite.... 

In this research, transient liquid phase (TLP) bonding of FSX-414 superalloy was investigated using MBF-80 interlayer. The bonding was performed at different temperatures (1050-1200oC) for various times (1-120min). Also, different gap sizes were studied using the interlayer with various thicknesses (25-100µm). Homogenizing treatment was performed at different temperatures (1175-1225oC) and times (1-6h) for the samples with complete isothermal solidification. The microstructure of the samples were studied using the optical, scanning electron and transmission electron microscopes. Also, XRD, SEM/EDS, SEM/WDS and TEM/EDS analyses were used to analyse the observed phases at the joints. To... 

In the research transient liquid phase bonding of AL6061-SiC composite was performed using copper as interlayer. The joining praocess was performed in various tetemperatures (560c and 580c and 600c) And times (6 and 8 hours). Optimum Joining condition was determined by using optical and of the joint, micro hardness test was performed from the bonding zone to the bulk of the base composite. The fatigue endurance limit of Al6061-SiC composite was determined by several fatigue tests and TLP bonded samples were loaded under achieved endurance limit stress. Finally fatigue fracture surface of both base composite and TLP bonded samples were studied by using of scanning electronic microscope  

Interlayer composition as one of the most important factors of TLP bonding could affect bonding region composition and microstructure that both of them govern the mechanical properties of the joint. Due to the risk of substrate microstructure degradation , welding of dual phase steel needs more cautions. TLP bonding ideally acquires joints having more similar microstructure to substrate. Moreover , using this method could avoid the change of base metal microstructure when heat treatment of carbon steel is postponed until after bonding. Fe-based , Ni-based and commercially pure Cu are three different composition has been studied in this work. The bonded samples were investigated by optic and... 

Dual Phase ferritic-martensitic steels are kind of high strength low alloy steels (HASLA) which are widely used in industry because of their strength and formability. Since welding of dual phase steels in conventional welding methods causes structural change and Subsequently alters mechanical properties of both weld zone and heat affected zone(HAZ), additional operations which are not commercially viable is needed to achieve a dual phase structure in structurally changed regions. In this study, transient liquid phase (TLP) bonding method is used during dual phasing process in order to preserve dual phase ferritic-martensitic structure and avoid extra heat treatment. Applied pressure during... 

Stainless steels have many applications in different industries like chemistry, medicine and food production. So for using these alloys it is necessary to join them with appropriate method. In this research, microstructure-mechanical properties relationship of 304LC austenitic stainless steel transient liquid phase bonded using a Co-based interlayer was investigated. For this purpose, bonding was conducted at 1180 ℃ for different holding times. Microstructure of the joints was evaluated by optical microscopy (OM) and Scanning Electron Microscopy (SEM). The results showed that isothermal solidification (IS) was completed within 1800s and no intermetallic compound was formed in the joint area...