Search for: phase-separation
Total 72 records
Simulating Dynamics of Immiscible Liquids Separation Using Microfluidics, 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...
Phase Separation in Binary Liquid Crystal Mixtures, 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
Preparation and Characterization of Polymeric Nanocomposite Membrane used in Li-Ion Batteries, 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...
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...
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...
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...
Extraordinary swelling behavior of poly (AMPS) organogelin solvent/DMSO binary mixed media, Article Journal of Applied Polymer Science ; Volume 117, Issue 2 , July , 2010 , Pages 1127-1136 ; 00218995 (ISSN) ; Kabiri, K ; Kheirabadi, M ; Sharif University of Technology
The present article deals with super-swelling behavior of crosslinked homopolymer of 2-acrylamido-2-methylpropane sulfonic acid, poly(AMPS), in binary mixtures of dimethyl sulfoxide (DMSO) and various polar solvents including water, mono-, and polyhydric alcohols, and amide solvents such as N-methyl pyrrolidone. Extraordinary phase transition sequences including a new unusual swelling phenomenon, referred to as "overentrant" swelling, was observed for this polymeric organogel in the solvent/DMSO mixtures. The swelling behaviors were preliminarily explained based on the major interactions involved in the solvation process and dielectric constant of the swelling media. It was established that...
Generic extraction medium: From highly polar to non-polar simultaneous determination, Article Analytica Chimica Acta ; Volume 1066 , 2019 , Pages 1-12 ; 00032670 (ISSN) ; Khalilzadeh, M ; Bagheri, H ; Sharif University of Technology
Elsevier B.V 2019
Sample preparation for non-target analysis is challenging due to the difficulty in the extraction of polar and non-polar analytes simultaneously. Most commercial solid sorbents lack the proper comprehensiveness for extraction of analytes with different physiochemical properties. A possible key is the combination of hydrophobic polymer and hydrophilic surface functional groups in solid based extraction methods in order to generate the susceptibility for retaining both polar and non-polar analytes. To pursue this goal, in this study, four polar groups including [sbnd]NH 2 , [sbnd]NO 2 , [sbnd]COOH, and [sbnd]COCH 3 were chemically bound to Amberlite XAD-4 substrate in order to prepare a...
Melt compounding of thermoplastic polyurethanes incorporating 1D and 2D carbon nanofillers, Article Polymer - Plastics Technology and Engineering ; Volume 56, Issue 7 , 2017 , Pages 732-743 ; 03602559 (ISSN) ; Pedrazzoli, D ; Pircheraghi, G ; Manas Zloczower, I ; Sharif University of Technology
Taylor and Francis Inc 2017
Thermoplastic polyurethane nanocomposites incorporating carbon nanotubes and graphene nanoplatelets were prepared through melt blending and compression molding, and the compounding process was optimized taking into account the different physical properties of one-dimensional carbon nanotubes and two-dimensional graphene nanoplatelets. Filler dispersion was further improved in the case of carbon nanotubes by noncovalent surface modification using a specific surfactant. The well-dispersed nanofillers favored enhanced phase separation in the thermoplastic polyurethane, leading to a better microstructure, which is able to improve the load transfer and maximize the tensile and viscoelastic...
Property Investigation of Poly (Ethylene Co-vinyl Acetate)/Poly (l-Lactic Acid)/Organo Clay Nanocomposites, Article Journal of Polymers and the Environment ; Volume 27, Issue 12 , 2019 , Pages 2886-2894 ; 15662543 (ISSN) ; Ramazani SaadatAbadi, A ; Sharif University of Technology
Springer New York LLC 2019
In this study, EVAc/PLA/organo clay nanocomposites were prepared via solution mixing method. The SEM images were used to investigate the morphology of nanocomposites revealing no phase separation or agglomeration of disperse phase in EVAc/PLA blends and nanocomposites. SAXS spectra confirmed the intercalated morphology of nanocomposites. Soil burial test were carried out and the rate of degradation of the samples were measured indirectly. Oxygen gas permeability of EVAc was slightly decreased by adding PLA to the matrix, when small loads of clay caused dramatic improvement in barrier properties. Melt rheological frequency sweep test illustrated the compatibility of EVAc with low contents of...
Spin and charge fluctuations in a one-dimensional lattice with long-range interactions, Article Physica B: Condensed Matter ; Volume 571 , 2019 , Pages 204-209 ; 09214526 (ISSN) ; Davoudi, B ; Sharif University of Technology
Elsevier B.V 2019
We study the competition between spin and charge fluctuations of the extended Hubbard model with on-site and dipole-dipole interactions in a one-dimensional lattice. Using the extended two-particle self consistent (ETPSC) method, we find the corresponding expressions for spin and charge response functions. In this approach, the irreducible spin and charge vertices are a function of inter-particle distance (r) and wave-number (q). This theory allows us to determine the crossover temperatures and the dominant instability as a function of U and V. The phase diagrams are obtained for several effective particle densities: n = 0.5, n = 1 and n = 4/3. Each phase diagram (U − V − T space)...
Preparation of amine–modified lignin and its applicability toward online micro–solid phase extraction of valsartan and losartan in urine samples, Article Journal of Chromatography A ; Volume 1643 , 2021 ; 00219673 (ISSN) ; Zeinali, S ; Bagheri, H ; Sharif University of Technology
Elsevier B.V 2021
In the present work, with the focus on an environmentally–friendly approach, some gels were prepared by synthesizing amine–modified lignin, extracted from sugarcane bagasse, and further esterification and subsequent freeze–drying. These lignin–based gels were implemented as extractive phases in an online micro–solid phase extraction (μSPE) setup in conjunction with high performance liquid chromatography (HPLC) with UV detector. The developed method was used for analytical determination of valsartan and losartan in urine samples. To study the effect of the functionalization process, the efficiency of the unmodified lignin and the functionalized lignin were compared both in the absence and the...
Bio-based UV curable polyurethane acrylate: Morphology and shape memory behaviors, Article European Polymer Journal ; Volume 118 , 2019 , Pages 514-527 ; 00143057 (ISSN) ; Shojaei, A ; Sundararaj, U ; Sharif University of Technology
Elsevier Ltd 2019
Smart bio-based shape memory polymers with high performance and fast response have the exciting potential to meet the growing need in biomedical applications. In this study, novel fast response UV-curable shape memory polyurethane acrylates (SMPUAs) comprising polycaprolactone diols (PCL-Diol), hexamethylene diisocyanate (HDI) and hydroxy-methyl methacrylate (HEMA) were synthesized by two-step bulk polymerization. Two series of PUAs with almost the same amount of hard segment content (HSC) were prepared with varying soft-segment molecular weight (2000, 3000, and 4000 g/mol) and different molar ratios of constituents. A mono-functional reactive diluent was used to control HSC and reduce the...
Immobilization of synthesized phenyl-enriched magnetic nanoparticles in a fabricated Y–Y shaped micro-channel containing microscaled hedges as a microextraction platform, Article Analytica Chimica Acta ; Volume 1136 , 2020 , Pages 51-61 ; Hedeshi, M. H ; Bagheri, H ; Sharif University of Technology
Elsevier B.V 2020
In this survey, a reliable and applicable Y–Y shaped micro–channel in a microfluidic device was designed and manufactured. A number of micro–scaled hedges were precisely fabricated inside the micro–channel to facilitate the immobilization of synthesized core–shell Fe3O4@SiO2 magnetic nanoparticles (MNPs), functionalized by triethoxyphenylsilane (TEPS) by sol-gel technique. Both sample and reagents were introduced into the microfluidic device by a syringe pump to perform the extraction and desorption steps. The functionalized MNPs were characterized by transmission electron microscopy, X-ray diffraction spectroscopy and Fourier transform infrared spectroscopy. By adopting the strategy of...
Multi-response optimization followed by multivariate calibration for simultaneous determination of carcinogenic polycyclic aromatic hydrocarbons in environmental samples using gold nanoparticles, Article RSC Advances ; Volume 6, Issue 106 , 2016 , Pages 104254-104264 ; 20462069 (ISSN) ; Parastar, H ; Hormozi Nezhad, M. R ; Sharif University of Technology
Royal Society of Chemistry
In this study, a multivariate-based strategy was developed for simultaneous determination of thirteen carcinogenic polycyclic aromatic hydrocarbons (PAHs) in water samples using gold nanoparticles (AuNPs) as solid-phase extraction (SPE) sorbent combined with gas chromatography (GC). The extraction technique is based on the strong affinity between citrate-capped AuNPs and PAHs. Furthermore, characterization of AuNPs was performed by UV-vis spectroscopy and transmission electron microscopy (TEM) techniques. A rotatable central composite design (CCD) combined with multiple linear regression (MLR) was used for designing the extraction procedure and developing models using the GC peak areas of 13...
TPU/graphene nanocomposites: effect of graphene functionality on the morphology of separated hard domains in thermoplastic polyurethane, Article Polymer ; Volume 148 , 18 July , 2018 , Pages 169-180 ; 00323861 (ISSN) ; Pircheraghi, G ; Sharif University of Technology
Elsevier Ltd 2018
Graphene nanoplatelets with different surface functional groups and polarity were prepared by Hummer's method and electrochemical exfoliation of graphite in two aqueous acids. The XRD, FTIR and sedimentation tests performed to characterize the polarity of the prepared graphenes. The highest polarity was associated with the sample prepared by Hummer's method and the sample synthesized by electrochemical exfoliation in nitric acid medium showed the moderate polarity. Meanwhile, the sample prepared in sulfuric acid medium showed the lowest polarity. Then thermoplastic polyurethane (TPU)/graphene nanocomposite films were fabricated with solvent exchange method. While the dispersion state and...
A mechanistic understanding of the water-in-heavy oil emulsion viscosity variation: effect of asphaltene and wax migration, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 608 , 2021 ; 09277757 (ISSN) ; Hemmati, M ; Safari, M ; Rahimi, A ; Rahmani, O ; Aminpour, S. M ; Beiranvand Pour, A ; Sharif University of Technology
Elsevier B.V 2021
The role of emulsions as a prevalent phenomenon is broadly investigated in the petroleum industry since forming the emulsion has many severe harmful implications. Heavy components of crude oil such as wax and asphaltene make the water-in-oil (w/o) emulsion more stable, while the role of these components on the emulsion viscosity has not been fully understood. In this regard, to find a proper demulsifier to break these emulsions, it is necessary to know the mechanisms of emulsion formation by heavy oil components. In this study, the effects of waxy-oil and asphaltenic-oil on w/o emulsion were investigated by measuring volume and viscosity of the formed emulsion after an elapsed time, followed...
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...
Molecular engineering and morphology of polyurethane elastomers containing various molecular weight of macrodiol, Article Materials Science and Engineering B: Solid-State Materials for Advanced Technology ; Volume 264 , 2021 ; 09215107 (ISSN) ; Zuber, M ; Barikani, M ; Salman, M ; Sharif University of Technology
Elsevier Ltd 2021
A series of polyurethane elastomers (PUEs) based on 4,4′-cyclohexamethylene diisocyanate (H12MDI)/1,2-ethanediol as hard segment with the soft segments having different molecular weights of polycaprolactone diols, were effectively polymerized by two step technique. The structural characterization was performed by FT-IR spectroscopy. The X-ray diffraction (XRD) technique was used to study the crystallinity and hydrophilicity of the prepared polymer films. It was found that crystallinity and hydrophilicity increased with increasing the chain length of soft segments. The effect of molecular weight of polyols on the contact angle, water absorption (%) and swelling behavior of the synthesized...