Search for: phase-separation
Total 78 records
Porous Structured of Polystyrene by Phase Separation in Liquid Nitrogen for Immersed Solvent Supported µ-extraction of Polycyclic Aromatic Hydrocarbons, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib
Porous materials using polymers have been developed for a variety of industrial applications. These structures mostly contain well-aligned microchannels and exhibit good mechanical properties and high porosity.There are several ways to prepare porous polymeric structures, such as sintering, stretching, track etching and phase separation processes. In this work Phase separation method using anti-solvent of selected polymer in liquid nitrogen was used to fabricate the porous structures. Considering physical and chemical peroperties of polycyclic aromatic hydrocarbons, porous polystyrene make to be good sorbents. Solvent supported microextraction technique was applied to extract polycyclic...
M.Sc. Thesis Sharif University of Technology ; Pircheraghi, Gholamreza
In Lithium ion batteries, the separator is membrane that placed between the cathode and the anode is one of critical components. Its primary function is to effectively transport ionic charge carriers between two electrodes as an efficient ionic conductor as well as to prevent the electric contact between them as a good electric insulator. The separator does not involve directly in any cell reactions, but its structure and properties play an important role in determining the battery performance. Commercially available polyolefin separators low cost, good electric resistance, high electrochemical stability, and effectively prevent thermal runaway caused by the electrical short-circuits or...
Numerical Investigation of Turbulent Flow Inside De-Oiling Hydrocyclones Using Large Eddy Simulation Approach, M.Sc. Thesis Sharif University of Technology ; Farhanieh, Bijan
Hydrocyclones are used for separating different materials from liquids in a variety of applications. Compactness, efficiency, reliability and low maintenance costs are their noteworthy characteristics. Dewatering and deoiling hydrocyclones used for refining crude oil or oily waste water in offshore platforms are examples of liquid-liquid hydrocyclones. Separation process in hydrocyclones is based on the fact that swirl flow induces a centrifugal force and leads to separation due to density difference. The density difference in liquid-liquid mixtures is smaller than solid-liquid types and trying to separate one liquid from another takes much more effort than the other type. Increase of...
Study on the Exfoliation of Graphite into Graphene by Electrochemical Method and Its Application in Thermoplastic Polyurethane Nanocomposite, M.Sc. Thesis Sharif University of Technology ; Pircheraghi, Gholamreza
Graphene is two dimensional nanomaterial, single layer of carbon atoms that exhibited excellent properties like high electrical conductivity and stiffness, but producing graphene and obtaining a good dispersion of graphene in a polymer matrix is still a major challenge. In this study by using the electrochemical route several graphene with different degree of oxidation produced in different electrolyte medium. According to XRD data, product of electrochemical exfoliation in dilute HNO3 medium includes 50% few-layer graphene (5 layers) and 25% GO and the rest are multi-layer graphene. Nonsolvent induced phase separation method were used to prepare TPU/Graphene nanocomposite. Different methods...
M.Sc. Thesis Sharif University of Technology ; Mohammadi, Aliasghar
Most of industrial and laboratory processes are faced with liquid-liquid emulsions particularly aqueous-organic ones in their different product streams which determine the need to perform phase separation due to enviromental problems or need to increase the product purity. In this project, due to presence of a water-hexane two phase flow mixture in the outflow of a microractor that performs Lithium-Bromine exchange reaction, a capillary microchip separator has been designed in order to separate water through capillary channel and hexane through main channel outlet using interfacial forces and wettability effects. To obtain a desired phase separation, the pressure drop through main channel...
M.Sc. Thesis Sharif University of Technology ; Ejtehadi, Mohammad Reza
Phase separation of a 50:50 binary system composed of two prolate ellipsoids with different axis ratios is investigated through molecular dynamics simulation. The system can be considered as a coarse-grained model of a binary liquid crystal mixture. Phase separation has been detected in the system by changing the density as the control parameter. The system goes through two different phase changes, one being the phase change due to phase separation and the other one due to orientational phase transition. In the latter case coexistence of the two particles results in simultaneous phase transition
Construction of Suitable Polymeric Membrane by Thermal Induce Phase Separation (TIPS) for using in the Membrane Bioreactor (MBR), M.Sc. Thesis Sharif University of Technology ; Farhadi, Fathollah ; Mousavi, Abbas
In this study, the response surface methodology (RSM) based on the central composite design (CCD) were used to prepare a polypropylene grafted maleic anhydride (PP-g-MA) microporous flat sheet membrane via thermally induced phase separation (TIPS) method. Mixture of dibutyl phthalate (DBP) and dioctyl phthalate (DOP) were used as diluent. The effect of the polymer composition and coagulation bath temperature on the morphology and performance of the fabricated microporous membranes in a bioreactor (MBR) were investigated. Analysis of variance (ANOVA) was used to determine which variables and interactions between variables have a significant effect on our responses. The ANOVA revealed that the...
M.Sc. Thesis Sharif University of Technology ; Mashayekhan, Shohreh
Cranioplasty is a surgical procedure for repairing skull defects. This surgery will protect the brain tissue, reduce pain in the lesion site and reduce the psychological burden on the patient. Cranioplasty implants should have distinct characteristics, i.e., high strength for protecting the brain, full coverage of skull defects, resistance to infection, non-expansion with heat, and reasonable price. Titanium implants, bone allografts, hydroxyapatite, and methyl methacrylate are commonly used in this surgery. However, these materials have many disadvantages that limit their use. As a result, biodegradable material and 3D printing technology are the next steps for designing scaffolds according...
Article Journal of Membrane Science ; Vol. 470, issue , 2014 , pp. 159-165 ; ISSN: 03767388 ; Soltanieh, M ; Sharif University of Technology
A high silica CHA-type membrane was synthesized by the in-situ crystallization method on a disk like α-alumina porous support to separate both acid (H2S, CO2) gases from methane. The membrane showed a permeance of 3.39×10-8mol/m2sPa for pure CO2with CO2/CH4 ideal selectivity of 21.6 at 303K and 100kPa pressure difference across the membrane. The membrane was also tested with N2 and O2 pure gases indicating a small O2/N2 selectivity of 1.2-1.4, which shows that this type of membrane is not suitable for O2/N2 separation. The membrane performance was also analyzed by binary (CO2-CH4) and ternary (H2S-CO2-CH4) gas mixtures, with compositions near the real sour natural gas (CO2: 2.13mol%, H2S:...
Article Physica C: Superconductivity and its Applications ; Volume 497 , 15 February , 2014 , 2014, Pages 84-88 ; ISSN: 09214534 ; Rasti, M ; Akhavan, M ; Sharif University of Technology
The details of the crystal structure of the recently discovered Y 3Ba5Cu8O18+δ (Y358) superconductor have been determined by ab initio density functional theory. Total energy calculation has been performed for three different suggested structures with different oxygen content. The structure with a center of inversion symmetry and the highest oxygen concentration has the lowest total energy. Thus, it is the best choice for the Y358 crystal structure. By investigating the detailed structure, it is seen that this compound is arranged either of YBa2Cu3O7 and YBaCu2O 5 or YBaCu2O5 and BaCuO2 substructural blocks in the c direction. The difference between the total energy of Y358 compound and the...
Electrospun titania sol-gel-based ceramic composite nanofibers for online micro- solid-phase extraction with high-performance liquid chromatography, Article Journal of Separation Science ; Vol. 37, issue. 15 , August , 2014 , pp. 1982-1988 ; ISSN: 16159306 ; Piri-Moghadam, H ; Rastegar, S ; Taheri, N ; Sharif University of Technology
Titanium(IV) tetraisopropoxide was employed as a metal oxide sol-gel precursor to prepare ceramic composite nanofibers by the electrospinning system. To facilitate this process and obtain the desired nanofibers with higher aspect ratios and surface area, poly(vinylpyrrolidone) was added to the sol of titania. Four ceramic nanofibers sheets based on titania were prepared while each sheet contained different transition metals such as Fe-Mn, Fe-Ni, Fe-Co, and Fe-Mn-Co-Ni. The scanning electron microscope images showed good homogeneity for all the prepared ceramic composites with a diameter range of 100-250 nm. The sorption efficiency was investigated by a micro-solid-phase extraction setup in...
Preparation and characterization of SAPO-34 nanoparticles-mixed matrix membranes (MMM) via combined phase separation method for CO2/CH4 gas separation application, Article Technical Proceedings of the NSTI Nanotechnology Conference and Expo, NSTI-Nanotech ; Vol. 1 , 2014 , pp. 253-256 ; ISBN: 9781482258264 ; Soltanieh, M ; Azadi, R ; Sharif University of Technology
Phase separation is one of the common methods for fabrication of polymeric membrane, which classifies into the categories of Thermally Induced Phase Separation (TIPS) and Nonsolvent Induced Phase Separation (NIPS), i.e. heat and mass transfer induced phase separation, respectively. NIPS has been applied more commonly than TIPS, but the membranes which have resulted from this technique have macro finger-like voids, weak mechanical strength and not high separation ability in comparison with the TIPS. In contrast, membranes produced by the TIPS method have micro scale pores, high mechanical strength and also high separation capability, however, polymeric solutions prepared at high temperatures...
A novel magnetic poly(aniline-naphthylamine)-based nanocomposite for micro solid phase extraction of rhodamine B, Article Analytica Chimica Acta ; Volume 794 , 2013 , Pages 38-46 ; 00032670 (ISSN) ; Daliri, R ; Roostaie, A ; Sharif University of Technology
A novel Fe3O4-poly(aniline-naphthylamine)-based nanocomposite was synthesized by chemical oxidative polymerization process as a magnetic sorbent for micro solid phase extraction. The scanning electron microscopy images of the synthesized nanocomposite revealed that the copolymer posses a porous structure with diameters less than 50nm. The extraction efficiency of this sorbent was examined by isolation of rhodamine B, a mutagenic and carcinogenic dye, from aquatic media in dispersion mode. Among different synthesized polymers, Fe3O4/poly(aniline-naphthylamine) nanocomposite showed a prominent efficiency. Parameters including the desorption solvent, amount of sorbent, desorption time, sample...
High-throughput micro-solid phase extraction on 96-well plate using dodecyl methacrylate-ethylen glycol dimethacrylate monolithic copolymer, Article Analytica Chimica Acta ; Volume 792 , August , 2013 , Pages 59-65 ; 00032670 (ISSN) ; Es'haghi, A ; Es-haghi, A ; Mohammadkhani, E ; Sharif University of Technology
A novel high-throughput device based on 96-micro-solid phase extraction (96-μ-SPE) system was constructed for multiresidue determination of nine pesticides in aquatic samples. The extraction procedure was performed on a commercially available 96-well plate system. The extraction module consisted of 96 pieces of 1cm×3cm of cylindrically shaped stainless steel meshes. The prepared meshes were fixed in a home-made polytetrafluoroethylene-based constructed ninety-six holes block for possible simultaneous immersion of meshes into the center of individual wells. Dodecyl methacrylate and ethylene glycol dimethacrylate was copolymerized as a monolithic polymer and placed in the cylindrically shaped...
Multivariate curve resolution-particle swarm optimization: A high-throughput approach to exploit pure information from multi-component hyphenated chromatographic signals, Article Analytica Chimica Acta ; Volume 772 , 2013 , Pages 16-25 ; 00032670 (ISSN) ; Ebrahimi Najafabadi, H ; Jalali Heravi, M ; Sharif University of Technology
Multivariate curve resolution-particle swarm optimization (MCR-PSO) algorithm is proposed to exploit pure chromatographic and spectroscopic information from multi-component hyphenated chromatographic signals. This new MCR method is based on rotation of mathematically unique PCA solutions into the chemically meaningful MCR solutions. To obtain a proper rotation matrix, an objective function based on non-fulfillment of constraints is defined and is optimized using particle swarm optimization (PSO) algorithm. Initial values of rotation matrix are calculated using local rank analysis and heuristic evolving latent projection (HELP) method. The ability of MCR-PSO in resolving the chromatographic...
Article Thin Solid Films ; Volume 520, Issue 20 , 2012 , Pages 6355-6360 ; 00406090 (ISSN) ; Afshar, A ; Dolati, A ; Sharif University of Technology
In this study, TiO 2-SiO 2 nanocomposite films with different amounts of SiO 2 were prepared by sol-gel process and were coated onto stainless steel 316L. The effect of addition of various amount of SiO 2 in the precursor solution on the photocatalysis, photo-generated hydrophilicity and self-cleaning property of TiO 2 thin films was investigated by X-ray diffraction, Fourier transform infrared spectroscopy, water contact angle measurements and UV spectroscopy. In the tested ranges of SiO 2 content and sintering temperature, the highest photocatalytic activity and self-cleaning property were observed in the 15 mol% SiO 2 sample sintered at 750 °C. Addition of less than 30 mol% SiO 2 had a...
Article Journal of the European Ceramic Society ; Volume 32, Issue 11 , August , 2012 , Pages 2989-2994 ; 09552219 (ISSN) ; Nemati, A ; Baghshahi, S ; Sharif University of Technology
Formation of transparent glass-ceramic in the system MgO-SiO 2-Al 2O 3-K 2O-B 2O 3-F with and without addition of LiF and NaF has been investigated. Crystallization of glass-sample was conducted by controlled thermal heat-treatment, at determined nucleation and crystallization temperatures. In this regard, the effects of addition of LiF and NaF were investigated on the crystallization behavior and transparency of the samples. Low transmission (less than 80% at 600. nm) was observed in the basic composition (K).The addition of NaF and LiF caused more intense phase separation in the system. The results indicated that the glass-ceramic can remain transparent if fine grains with nano size are...
Simulation of two-phase liquid-vapor flows using a high-order compact finite-difference lattice Boltzmann method, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 92, Issue 5 , November , 2015 ; 15393755 (ISSN) ; Ezzatneshan, E ; Sharif University of Technology
American Physical Society 2015
A high-order compact finite-difference lattice Boltzmann method (CFDLBM) is extended and applied to accurately simulate two-phase liquid-vapor flows with high density ratios. Herein, the He-Shan-Doolen-type lattice Boltzmann multiphase model is used and the spatial derivatives in the resulting equations are discretized by using the fourth-order compact finite-difference scheme and the temporal term is discretized with the fourth-order Runge-Kutta scheme to provide an accurate and efficient two-phase flow solver. A high-order spectral-type low-pass compact nonlinear filter is used to regularize the numerical solution and remove spurious waves generated by flow nonlinearities in smooth regions...
Sol-gel-based silver nanoparticles-doped silica - Polydiphenylamine nanocomposite for micro-solid-phase extraction, Article Analytica Chimica Acta ; Volume 886 , July , 2015 , Pages 56-65 ; 00032670 (ISSN) ; Banihashemi, S ; Sharif University of Technology
A nanocomposite of silica-polydiphenylamine doped with silver nanoparticles (Ag-SiO
2-PDPA) was successfully synthesized by the sol-gel process. For its preparation, PDPA was mixed with butanethiol capped Ag nanoparticles (NPs) and added to the silica sol solution. The Ag NPs were stabilized as a result of their adsorption on the SiO 2 spheres. The surface characteristic of nanocomposite was investigated using scanning electron microscopy (SEM). In this work the Ag-SiO 2-PDPA nanocomposite was employed as an efficient sorbent for micro-solid-phase extraction (μ-SPE) of some selected pesticides. An amount of 15 mg of the prepared sorbent was used to extract and...
Experimental study and thermodynamic modeling for purification of extracted algal lipids using an organic/aqueous two-phase system, Article RSC Advances ; Volume 5, Issue 2 , 2015 , Pages 1153-1160 ; 20462069 (ISSN) ; Pazuki, G ; Vossoughi, M ; Sharif University of Technology
Royal Society of Chemistry 2015
The extraction and purification of lipids from the microalgae Chlorella vulgaris have been investigated. First, a mixture of hexane and ethanol was used to extract lipids from the algal biomass. Ultrasonication was employed to disrupt the cell wall and increase the extraction performance. Under these conditions, over 90% of the fatty acids in the biomass were extracted. Second, a biphasic system was formed by adding water and hexane to the extracted crude oil. In this way, fatty acids were mainly distributed in the organic phase (mostly hexane and ethanol) while most of the contaminants remained in the aqueous phase (mostly water and ethanol). Equilibrium distribution data between the phases...