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Separation of Metal Ions-based Microfluidic Platform for Liquid-liquid Extraction
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Ali Asghar (Supervisor) ; Karimi Sabet, Javad (Co-Advisor)
Abstract
Continuous separation processes in microfluidic devices experienced a steep rise in attention during the last two decades. Among the different separation processes, liquid-liquid extraction especially benefits from the short molecular diffusion distance and large specific interfacial area, as these are advantageous for effective mass transport. In the present study, glass-based microfluidic devices have been fabricated utilizing laser ablation and wet chemical etching methods then experiments and numerical simulation were carried out to investigate hydrodynamic behavior of fluid flow in Y-junction microfluidic. In order to achieve phase separation at the end of the microchannel, a phase...
YSZ Coating on Ferritic Stainless Steel Interconnect through Sol-Gel Method and Studying its Reaction with Glass Sealant in SOFC
, M.Sc. Thesis Sharif University of Technology ; Faghihi Sani, Mohammad Ali (Supervisor) ; Nemati, Ali (Supervisor)
Abstract
Solid oxide fuel cells are used to convert solid-state energy to direct electrical current by electrochemistry mixing a gas fuel and an oxidant in an oxide electrolyte. One of the most interesting aspects of this field for the researchers is the reaction between the metal interconnect and the glass sealant. In the current research, deposition of the YSZ coating onto the metal interconnect in order to impede the reaction with glass sealant and prohibition of its oxidation in oxidizing/reducing environment in high temperature, was mainly investigated. Effect of applying YSZ Thin layer in the intersection of Crofer steel and glass sealant on strength and chemical durability of these two...
Molecular Dynamic Study of Short-and Medium-Range order Structures in Bulk Metallic Glasses
, Ph.D. Dissertation Sharif University of Technology ; Aashuri, Hosien (Supervisor) ; Tavakoli, Roholah (Supervisor)
Abstract
In this work, structures of Cu-Zr bulk metallic glasses at atomic scale were studied by molecular dynamics simulation. Bulk metallic glasses have high glass form ability, which makes it possible to more effectively examine the relationship between structure and properties in glassy materials. Due to this reason, this family of materials has been selected in this research. Voronoi tessellation method, coordination number analysis, short-range order examination, glass transition temperature and pair distribution function have been selected to investigate the structure in atomic scale. Results show that full icosahedron (with the highest five-fold symmetry) and some distorted icosahedra have...
Introducing a Numerical Method for Estimating Median Crack Depth during Machining on Optical Glasses
, Ph.D. Dissertation Sharif University of Technology ; Akbari, Javad (Supervisor)
Abstract
In present research, a cohesive based finite element model has been introduced to estimate median crack depth during mechanical machining on optical glasses. Development of the machining numerical model has been initiated by investigating the indentation process. Experimental results of this step have been calibrated primary numerical model which has been used in the scratch process. Due to differences between the scratch mechanism and indentation one, mathematical bases fracture formulas and cohesive relations have been developed. After extracting primary result, using them in the scratch model and developing the primary model, ultimately numerical model has been evolved to an abstract...
Ultrasonic-Assisted Drilling of Glass Fiber Reinforced Composites
, M.Sc. Thesis Sharif University of Technology ; Akbari, Javad (Supervisor)
Abstract
The fiber-reinforced composite materials possess advantage for structural purpose in various industries. Delamination is recognized as one of the major causes of damage during drilling of fiber reinforced composites, which not only reduces the structural integrity, but also has the potential for long-term performance deterioration. It is difficult to produce precise quality holes with high efficiency by conventional drilling method. Drilling is frequently applied in production cycle while the anisotropy and nonhomogeneity of composite materials affect the chip deformation and machining behavior during drilling. In this thesis, a new non-traditional drilling technology is presented for solve...
Bromine-lithium Exchange Reaction in Organic Synthesis Using Glass Microreactor
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Aliasghar (Supervisor)
Abstract
Today, microreactors come into focus due to their exclusive characteristics including high surface-to-volume, lower consumption of reagents and fast mixing. In this study, optimization of the Br-Li exchange reaction as a consecutive reaction using glass microreactor is investigated. To construct glass microreactor, laser ablation and thermal bonding method are utilized. In order to find the best yield and selectivity of the reaction, various parameters, such as solvent, equivalent ration of the two reagents, concentration of the reagents, residence time and flow rates of the reagents are examined. In addition, atomic force microscopy (AFM) analysis was used to determine the surface...
Microfluidic Tensiometry and Investigation of Nanoparticles Adsorption at Liquid/Liquid Interfaces
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Ali Asghar (Supervisor)
Abstract
The present paper is an attempt to critically measure interfacial tension with microchannels and achieve the quantity of adsorption in the liquid – liquid interfaces and comparing the adsorption of surfactants and nanoparticles surface modificated as well. At this point we need to make emulsion and it is necessary for droplets to be monodispersed due to analyze these droplets in this paper. According to this condition for our droplets microsystems are the best options. As we know surfactants were already known as a stabilizing emulsion agent and in this paper nanoparticles are suggested as suitable alternatives for surfactants which can be absorbed as if they are in the water / oil...
Bromo-lithium Exchange Reaction in Organic Synthesis and Continuous Separation of Organic and Aqueous phase Reactions by Microfloid Technique
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Ali Asghar (Supervisor) ; Bastani, Dariush (Supervisor)
Abstract
Today, with the development of micro-technology in chemical reactions, the use of appropriate systems for the separation and purification of synthesized chemicals seems to be necessary. In this study, the continuous synthesis of bromide-lithium exchange reaction and the separation of organic and aqueous phase products in micro systems was investigated.The method used to construct micro-separator and micro reactor, a laser engraving technique, and thermal bonding of glass to glass.In the first step, the factors affecting the separation of organic and aqueous phase in the capillary micro-separator, such as the width of the capillary, the length of the capillary, the number of capillaries and...
Feasibility Study on Ultrasonic Vibration Assisted Milling Process of BK7 Optical Glass
, M.Sc. Thesis Sharif University of Technology ; Akbari, Javad (Supervisor)
Abstract
This research studies the feasibility of the BK7 optical glass milling process with ultrasonic vibrations. Due to the fragility of glasses, especially optical glasses, machining is very sensitive and complex. For this reason, it is necessary to think for the glass machiners to minimize the defects and failures of the process. So far, efforts have been made to reduce the defects caused by machining on brittle materials, such as increasing the speed of the period, reducing the feed rate of the tool, changing the geometry and the type of tool, the type of process lubrication, etc. In addition, other operations performed to improve the surface of the glass are of better quality, using hybrid or...
Experimental Investigation on Debonding between FRP sheets and Structures
, M.Sc. Thesis Sharif University of Technology ; Toufigh, Vahab (Supervisor)
Abstract
This study has investigated the effects of different environmental conditions on the bond at the interface between two fiber reinforced polymer (FRP) layers. A total of 945 single lap splice coupons with three bond length were made using wet lay-up technic. There were used three unidirectional fabrics and one type of epoxy resin. A Uniaxial tensile test was performed on samples after 2, 4, 12, 20, 28, 36 and 48 weeks of exposure. Also series of test were conducted in order to determine the minimum lap splice length of single splice FRP samples. The experimental results indicated reduction of bond strength in glass specimens that was 17 % after 48 weeks of exposure while for same amount of...
Compressive Response of Cylindrical Concrete Columns Confined with Steel Spirals and GFRP Composites
, M.Sc. Thesis Sharif University of Technology ; Khalu, Alireza (Supervisor)
Abstract
Concrete structures require reinforcement and retrofitting because of possible mistakes in design or calculation, inconformity between plan and implementation, change in occupancy or applied loads, and decay. Development in technology, production of materials, and new methods play important roles in development of structure construction and reinforcement methods. Emerge of new materials creates great demand in studying, surveying, and determining design characteristic and criteria for these materials. One of these materials is FRP composite which is used in concrete structure reinforcement in different ways. In this laboratory research, the effect of external wrapping by GFRP composite...
The Investigation of Adsorption Desulfurization of Ethyl Mercaptan by Microfluidic Technology
, M.Sc. Thesis Sharif University of Technology ; Mohammadi, Ali Asghar (Supervisor)
Abstract
In recent years, desulfurization has received much attention due to its devastating environmental effects. The existence of sulfur compounds has effects such as corrosion, poisoning of catalysts, reduction of heat of combustion and reduction of price. Sulfur compounds in hydrocarbon fuels also produce sulfur oxides caused by combustion then they enter the atmosphere, and cause acid rain. Acid rain dissolves building materials, poisons lakes, and destroys forests. Therefore, removing sulfur or converting it to less harmful substances is one of the most important processes in refineries. The method studied in this research is the use of adsorption desulfurization method by microchannel which...
Evaluation of the Surface Activity of Novel Ionic Liquids and Their Application in the Enhanced Oil Recovery Process
, M.Sc. Thesis Sharif University of Technology ; Taghikhani, Vahid (Supervisor) ; Mokhtarani, Babak (Supervisor) ; Baghban Salehi, Mahsa (Co-Supervisor)
Abstract
The following dissertation discusses Ionic Liquids (ILs) as an alternative to commercial surfactants for use in the Enhanced Oil Recovery process. Ionic Liquids came to researchers’ attention due to their environmental nature and their tolerance for high temperatures and salinity. In this work, firstly, an extensive literature review is carried out, and then, experiments are designed and performed to evaluate ILs’ surface activity and performance in a lab-scale EOR set-up. The Ionic Liquids used in this work consist of three types of methylimidazolium nitrate, [MIM]+[NO3]-, with three different alkyl chain lengths. This combination, and specifically the effect of nitrate anions on EOR and...
Study of Self-Cleaning Silica Nano Coatings
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdollah (Supervisor)
Abstract
It has always been a challenge to make self-cleaning coatings based on super-hydrophobic properties that can provide the necessary features to be operational in the industry. One of these necessary features is the ability to easily apply the coating on the substrate and reduce the cost by finding the optimal amount of consumables. Therefore, in this research, at first, it was tried to produce silica nanoparticles with a particle size of less than 011 nm using the Stober method, and then the surface of the synthesized nanoparticles was coated with HDTMS (Hexadecyltrimethoxysilane) to make the silica particles, which are hydrophilic in nature, hydrophobic. According to the conducted studies,...
Preparation and characterization of nanostructured TiO2thin film codoped with nitrogen and vanadium on glass surface by sol–gel dip-coating method
, Article Research on Chemical Intermediates ; 2014 ; ISSN: 09226168 ; Sani, M. A. F ; Sharif University of Technology
Abstract
To enhance hydrophilicity and photocatalytic activity, N-doped and N–V-codoped TiO2films were coated on glass substrates by the sol–gel dip-coating method. The substrates were previously coated with SiO2using the same method. The coated samples, after annealing at 450 °C for 30 min in air, were analyzed by an X-ray diffractometer, scanning electron microscope, Fourier transform infrared spectroscope, X-ray photoelectron spectroscope, and UV–visible spectroscope. The SiO2/N–V-codoped TiO2photocatalyst showed a narrower band gap (2.93 eV) compared to the SiO2/N-doped. Degradation tests, methyl orange under UV light and stearic acid under visible light, were performed in order to evaluate...
Investigation of the microscopic displacement mechanisms and macroscopic behavior of alkaline flooding at different wettability conditions in shaly glass micromodels
, Article Journal of Petroleum Science and Engineering ; Vol. 122, issue , August , 2014 , pp. 595-615 ; ISSN: 09204105 ; Ghazanfari, M. H ; Sharif University of Technology
Abstract
Among various chemical methods, alkaline flooding has a great potential for enhancing heavy oil recovery, especially for reservoirs which contain acidic crude oil. However, fundamental understanding about microscopic displacement mechanisms and macroscopic behavior during alkaline floods at different wettabilities is not well understood, especially in five-spot shaly models. In this work several alkaline floods are performed on a glass micromodel containing randomly distributed shale streaks at different wettability conditions. Various mechanisms responsible for enhancing heavy oil recovery during alkaline flooding are investigated at different wettability conditions. These mechanisms...
Preconcentration and determination of carbaryl and carbofuran in water samples using ionic liquids and in situ solvent formation microextraction
, Article Analytical Methods ; Volume 5, Issue 9 , 2013 , Pages 2406-2412 ; 17599660 (ISSN) ; Givianrad, M. H ; Akhoundi, L ; Akhoundi, M ; Sharif University of Technology
2013
Abstract
In the present work, a novel microextraction method named in situ solvent formation microextraction (ISFME) using ionic liquids (ILs) for preconcentration of carbaryl and carbofuran in water samples is introduced. In this method, a small amount of sodium hexafluorophosphate (NaPF6), as an ion pairing agent, was added to a sample solution containing a small quantity of 1-hexyl-3-methylimidazolium tetrafluoroborate [Hmim][BF4] as a hydrophobic ionic liquid. A cloudy solution formed as a result of formation of fine droplets of 1-hexyl-3-methylimidazolium hexafluorophosphate [Hmim][PF 6]. After centrifugation, the fine droplets of the extractant phase settled to the bottom of the conical-bottom...
Self-cleaning TiO2 nanofilms on FTO glass: Influence of electrophoretic deposition and UV irradiation conditions
, Article Journal of Nano Research ; Volume 30 , 2015 , Pages 39-49 ; 16625250 (ISSN) ; Ghorbani, M ; Dolati, A ; Sharif University of Technology
Trans Tech Publications Ltd
2015
Abstract
In this research, anatase TiO2 nano-particles were electrophoretically deposited on the FTO glass. This investigation was focused on the self-cleaning property of TiO2 coatings and the effects of different parameters on this characteristic such as: applied voltages during electrophoretic depositions and durations of UV irradiation. Electrophoretic depositions of suspensions were performed in different voltages of 10, 30 and 60 V (for 10 s) at room temperature. TiO2 coatings were sintered in 450oC for 1 hr. The phase transformation of TiO2 films was considered using XRD. Morphology, average particle size and the thickness of TiO2 films was analyzed using FESEM microscope. The photocatalytic...
The axial and lateral behavior of low strength concrete confined by GFRP wraps: an experimental investigation
, Article Structures ; Volume 27 , October , 2020 , Pages 747-766 ; Tabatabaeian, M ; Khaloo, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
The purpose of this investigation is to investigate the axial and lateral behavior of low strength concrete confined by glass fiber reinforced polymer (GFRP) wraps. A total of 48 cylindrical samples having 150 mm diameter and 300 mm height were strengthened and examined. The mix designs were provided with four different target strength (5, 10, 15, and 20 MPa). The axial and lateral strain were studied to evaluate the axial strain relation and the lateral strain for axial compression. The results of this investigation present a comparison between the nine models previously reported for normal strength concrete and the lesser-known context of low strength concrete confined by fiber reinforced...
Crystallization and electrical properties of [(Pb1-xSrx)·TiO3][(2SiO2·B2O3)][K2O] glass-ceramics
, Article Journal of Materials Processing Technology ; Volume 206, Issue 1-3 , 12 September , 2008 , Pages 126-131 ; 09240136 (ISSN) ; Nemati, Z. A ; Alizadeh, P ; Bolandi, M ; Sharif University of Technology
2008
Abstract
The effect of compositional change on glass-ceramic formation and its electrical properties were studied. The composition was formulated with 40 wt.% of borosilicate glass, 60 wt.% of titanate and 10 wt.% of alkaline oxide. The glass samples with composition of [(Pb1-xSrx)·TiO3][(2SiO2·B2O3)][K2O] with different values of x (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) were prepared. After heat treatment of glasses at different temperatures, which were chosen based on differential thermal analysis-DTA curves, the crystallized phase and its microstructure were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD and SEM results revealed the formation of ferroelectric solid...