Search for: surface-active-agents
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    Near-white emitting QD-LED based on hydrophilic CdS nanocrystals

    , Article Journal of Luminescence ; Volume 132, Issue 2 , 2012 , Pages 467-473 ; 00222313 (ISSN) Molaei, M ; Marandi, M ; Saievar Iranizad, E ; Taghavinia, N ; Liu, B ; Sun, H. D ; Sun, X. W ; Sharif University of Technology
    In this work we report fabrication of a nanocrystal (NC)-based hybrid organicinorganic LED with structure of ITO/PEDOT:PSS/PVK/CdS-NCs/(Al or Mg:Ag). The hydrophilic CdS NCs were synthesized using a novel aqueous thermochemical method at 80 °C and sizes (around 2 nm) were controlled by thioglycolic acid (TGA) as the capping agent. The favorite feature of these NCs is their relatively high emission intensity and broad, near-white emission. The hydrophilic CdS NCs were successfully spin coated using Triton X-100 as the wetting agent. The fabricated LEDs demonstrated a turn on voltage about 7 V for Al metallic contact. The electroluminescence was a broad spectrum at 540 and 170 nm width, which... 

    Monodispersed polymeric nanoparticles fabrication by electrospray atomization

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 61, Issue 8 , 2012 , Pages 611-626 ; 00914037 (ISSN) Zarrabi, A ; Vossoughi, M ; Alemzadeh, I ; Chitsazi, M. R ; Sharif University of Technology
    The feasibility of fabricating relatively monodispersed polymeric nanoparticles by the electrospray method in a modified electrospray set-up is demonstrated in this study. The polymer solution is electrosprayed in the single cone-jet regime through a nozzle. After solvent evaporation, during which particles pave from the nozzle to collector, the fabricated nanoparticles can be collected in deionized water, which plays the role of surfactant for particles, not allowing them to aggregate. The results of scanning electron microscope and dynamic light scattering analysis clearly confirm the fabrication of monodispersed spherical polymeric nanoparticles with diameter range from 80 to 120nm with... 

    Monitoring the role of polymer and surfactant concentrations on bubble size distribution in colloidal gas aphron based fluids

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 556 , 2018 , Pages 93-98 ; 09277757 (ISSN) Pasdar, M ; Kazemzadeh, E ; Kamari, E ; Ghazanfari, M. H ; Soleymani, M ; Sharif University of Technology
    Elsevier B.V  2018
    Colloidal gas aphron (CGA) based fluids have recently been introduced to develop depleted hydrocarbon reservoirs due to their ability in controlling fluid losses. Bubbles size of CGAs plays an important role in pore blockage ability as the controlling mechanism in fluid invasion reduction. However, fundamental understanding of how bubble size distribution is controlled by polymer and surfactant concentrations is not well discussed in the available literature. Almost all reported experiences on CGAs sizing were conducted on single bubble behavior, and little attention has been given to the variation of bubble size distribution (BSD) of CGAs at different levels of polymer/surfactant... 

    Monitoring the effect of discontinuous shales on the surfactant flooding performance in heavy oil reservoirs using 2D glass micromodels

    , Article Petroleum Science and Technology ; Vol. 32, issue. 12 , Apr , 2014 , p. 1404-1417 ; ISSN: 10916466 Mohammadi, S ; Kharrat, R ; Masihi, M ; Ghazanfari, M. H ; Saidian, M ; Sharif University of Technology
    Although most heavy oil reservoirs contain discontinuous shaly structures, there is a lack of fundamental understanding how the shaly structures affect the oil recovery efficiency, especially during surfactant flooding to heavy oils. Here, an experimental study was conducted to examine the effect of discontinuous shales on performance of surfactant flooding by introducing heterogeneities to represent streaks of shale in five-spot glass micromodels. Results show that oil recovery in presence of shale streak is lower than in its absence. Based on the authors' observations, the presence of flow barriers causes premature breakthrough of injected fluids and also an unstable displacement front. As... 

    Modification of rock/fluid and fluid/fluid interfaces during MEOR processes, using two biosurfactant producing strains of Bacillus stearothermophilus SUCPM#14 and Enterobacter cloacae: A mechanistic study

    , Article Colloids and Surfaces B: Biointerfaces ; Vol. 117 , May , 2014 , pp. 457-465 ; ISSN: 09277765 Sarafzadeh, P ; Zeinolabedini Hezave, A ; Mohammadi, S ; Niazi, A ; Ayatollahi, S ; Sharif University of Technology
    During any microbial enhanced oil recovery process, both cells and the metabolic products of bacteria govern the tertiary oil recovery efficiency. However, very accurate examination is needed to find the functionality of these tiny creatures at different reservoir conditions. In this regard, the effect of cell structure on ultimate microbial recovery efficiency which is the most dominant mechanism based on the microorganism types (gram-negative or gram-positive) was systematically investigated. At the first stage, possible different active mechanisms using Bacillus stearothermophilus SUCPM#14 strain were tested using specially designed injection protocol, in situ and ex situ core flooding... 

    Modeling self-assembly of the surfactants into biological bilayer membranes with special chemical structures using dissipative particle dynamics method

    , Article Scientia Iranica ; Volume 23, Issue 3 , 2016 , Pages 942-950 ; 10263098 (ISSN) Yaghoubi, S ; Pishevar, A. R ; Saidi, M. S ; Shirani, E ; Sharif University of Technology
    Sharif University of Technology  2016
    The aim of this study is to simulate the self-assembly of the surfactant molecules with special chemical structure and bending stiffiness into bilayer membranes using a mesoscopic Dissipative Particle Dynamics (DPD) method. The surfactants are modeled with special chemical structure and bending stiffiness. To confirm that the novel model is physical, we determine the interaction parameters based on matching the compressibility and solubility of the DPD system with real physics of the uid. To match the mutual solubility for binary uids, we use the relation between DPD parameters and x-parameters in Flory-Huggins-type models. Unsaturated bonds can change the stiffiness of a lipid membrane,... 

    Model for excess mass-transfer resistance of contaminated liquid-liquid systems

    , Article Industrial and Engineering Chemistry Research ; Volume 46, Issue 5 , 2007 , Pages 1563-1571 ; 08885885 (ISSN) Molaei Dehkordi, A ; Ghasemian, S ; Bastani, D ; Ahmadpour, N ; Sharif University of Technology
    The prediction of mass-transfer rates into and from moving drops in the liquid-liquid systems has usually used the well-known Whitman two-film theory approach. According to the latter, the total resistance to mass transfer resides on each side of the interface and is described by the individual film mass-transfer coefficients for the continuous and dispersed phases in the absence of surface-active agents (contaminants). In the present work, the same approach has been used to model the excess mass-transfer resistance exerted by surface-active agents in the continuous phase. To achieve this goal, an experimental investigation has been conducted on the mass transfer into and from single drops... 

    Model development for MEOR process in conventional non-fractured reservoirs and investigation of physico-chemical parameter effects

    , Article Chemical Engineering and Technology ; Volume 31, Issue 7 , 2008 , Pages 953-963 ; 09307516 (ISSN) Behesht, M ; Roostaazad, R ; Farhadpour, F ; Pishvaei, M. R ; Sharif University of Technology
    A three-dimensional multi-component transport model in a two-phase oil-water system was developed. The model includes separated terms to account for the dispersion, convection, injection, growth and death of microbes, and accumulation. For the first time, effects of both wettability alteration of reservoir rock from oil wet to water wet and reduction in interfacial tension (IFT) simultaneously on relative permeability and capillary pressure curves were included in a MEOR simulation model. Transport equations were considered for the bacteria, nutrients, and metabolite (bio-surfactant) in the matrix, reduced interfacial tension on phase trapping, surfactant and polymer adsorption, and effect... 

    Microwave-assisted synthesis of narcis-like zinc oxide nanostructures

    , Article Journal of Alloys and Compounds ; Volume 497, Issue 1-2 , May , 2010 , Pages 325-329 ; 09258388 (ISSN) Kajbafvala, A ; Zanganeh, S ; Kajbafvala, E ; Zargar, H. R ; Bayati, M. R ; Sadrnezhaad, S. K ; Sharif University of Technology
    Through a fast, simple, low cost, surfactant-free and convenient microwave-assisted route, narcis-like ZnO nanostructures (10-15 nm size) with flower diameters in the range of 1-2.5 μm were synthesized. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and room temperature photoluminescence (PL) measurements were used to characterize the produced ZnO nanostructures. The principle raw materials - ammonium hydroxide (NH4OH) and zinc acetate dihydrate [Zn(CH3COO)2·2H2O] - were both inexpensive. The method was fast, simple and surfactant-free capable of producing larger quantities of zinc oxide... 

    Microorganisms’ effect on the wettability of carbonate oil-wet surfaces: implications for MEOR, smart water injection and reservoir souring mitigation strategies

    , Article Journal of Petroleum Exploration and Production Technology ; Volume 10, Issue 4 , 2020 , Pages 1539-1550 Jahanbani Veshareh, M ; Ayatollahi, S ; Sharif University of Technology
    Springer  2020
    In upstream oil industry, microorganisms arise some opportunities and challenges. They can increase oil recovery through microbial enhanced oil recovery (MEOR) mechanisms, or they can increase production costs and risks through reservoir souring process due to H2S gas production. MEOR is mostly known by bioproducts such as biosurfactant or processes such as bioclogging or biodegradation. On the other hand, when it comes to treatment of reservoir souring, the only objective is to inhibit reservoir souring. These perceptions are mainly because decision makers are not aware of the effect microorganisms’ cell can individually have on the wettability. In this work, we study the individual effect... 

    Mechanistic study of wettability alteration of oil-wet calcite: The effect of magnesium ions in the presence and absence of cationic surfactant

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 482 , October , 2015 , Pages 403-415 ; 09277757 (ISSN) Karimi, M ; Al Maamari, R. S ; Ayatollahi, S ; Mehranbod, N ; Sharif University of Technology
    Elsevier  2015
    Over 60% of the world's discovered oil reserves are held in carbonate reservoirs, which are mostly naturally fractured. Conventional water flooding results in low oil recovery efficiency in these reservoirs as most of them are oil-wet. On account of negative capillary forces, injected brine cannot penetrate simply into an oil-wet matrix of fractured formations to force the oil out. Wettability alteration of the rock surface to preferentially more water-wet state has been extensively studied using both smart water and surfactants separately. This study aims to study the effects of Mg2+ as one of the most important wettability influencing ions on the wetting properties of oil-wet carbonate... 

    Marangoni instabilities for convective mobile interfaces during drop exchange: Experimental study and CFD simulation

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Vol. 441, issue , 2014 , pp. 846-854 ; ISSN: 09277757 Javadi, A ; Karbaschi, M ; Bastani, D ; Ferri, J. K ; Kovalchuk, V. I ; Kovalchuk, N. M ; Javadi, K ; Miller, R ; Sharif University of Technology
    The inflow pattern of liquid into a droplet is studied experimentally using a surface active dye and compared with results of CFD simulations. The results show visual agreement between experiments and simulations. The CFD simulations show also good agreement with the surface tension measured by drop profile analysis tensiometry (PAT). The inflow of the surfactant induces a Marangoni instability caused by the local arrival of the surfactant at the drop surface. The onset of this Marangoni instability observed experimentally has a delay of about 10. s when compared with the simulation results. Different scenarios are discussed, including a boundary layer barrier, a kinetic-controlled... 

    Management of soybean oil refinery wastes through recycling them for producing biosurfactant using Pseudomonas aeruginosa MR01

    , Article World Journal of Microbiology and Biotechnology ; Volume 29, Issue 6 , June , 2013 , Pages 1039-1047 ; 09593993 (ISSN) Partovi, M ; Lotfabad, T. B ; Roostaazad, R ; Bahmaei, M ; Tayyebi, S ; Sharif University of Technology
    Biosurfactant production through a fermentation process involving the biodegradation of soybean oil refining wastes was studied. Pseudomonas aeruginosa MR01 was able to produce extracellular biosurfactant when it was cultured in three soybean oil refinement wastes; acid oil, deodorizer distillate and soapstock, at different carbon to nitrogen ratios. Subsequent fermentation kinetics in the three types of waste culture were also investigated and compared with kinetic behavior in soybean oil medium. Biodegradation of wastes, biosurfactant production, biomass growth, nitrate consumption and the number of colony forming units were detected in four proposed media, at specified time intervals.... 

    Macroscopic and microscopic investigation of alkaline-surfactant-polymer flooding in heavy oil recovery using five-spot micromodels: The effect of shale geometry and connatewater saturation

    , Article Journal of Porous Media ; Volume 18, Issue 8 , 2015 , Pages 745-762 ; 1091028X (ISSN) Mehranfar, A ; Ghazanfari, M. H ; Masihi, M ; Rashtchian, D ; Sharif University of Technology
    Begell House Inc  2015
    Plenty of oil reservoirs contain discontinuous shale layers that act as flow barriers. Therefore, understanding their influences on reservoir performance, especially during enhanced oil recovery (EOR) processes, is of great importance. For this purpose, several experiments of water and alkaline-surfactant-polymer (ASP) flooding have been performed on a number of one-quarter five-spot micromodels that contain various configurations of shale layers to simulate shaly porous media. Several features, such as various shale geometrical characteristics and the presence of connate water saturation, were investigated at both macro- and micro-scales. The presence of shales resulted in earlier... 

    Investigation of wettability alteration through relative permeability measurement during MEOR process: A micromodel study

    , Article Journal of Petroleum Science and Engineering ; Vol. 120, issue , 2014 , p. 10-17 Khajepour, H ; Mahmoodi, M ; Biria, D ; Ayatollahi, S ; Sharif University of Technology
    Microbial Enhanced Oil Recovery (MEOR) as a tertiary process employs microorganisms and their metabolites to reduce the residual oil saturation of the reservoir mainly through interfacial tension (IFT) reduction and wettability alteration. In spite of its great potential and the mentioned advantages, application of MEOR has been limited because of the lack of practical convincing experimental results. In this study, the effects of MEOR process on wettability changes and the reduction of residual oil saturation have been examined by providing microscopic visualization of two phase flow in transparent glass micromodels. Biosurfactant producing bacterial strain (Enterobacter cloacae) was... 

    Investigation of ionic liquids based on pyridinium and imidazolium as interfacial tension reducer of crude Oil−water and their synergism with MgCl2

    , Article Journal of Petroleum Science and Engineering ; Volume 171 , 2018 , Pages 414-421 ; 09204105 (ISSN) Lashkarbolooki, M ; Ayatollahi, S ; Sharif University of Technology
    Ionic liquids (ILs) can be tailored as chemical surfactants and surface active agents to reduce the interfacial tension (IFT) of crude oil/aqueous solutions for enhanced oil recovery processes. The current investigation was aimed to explore the nature of ingenious active agents in crude oil, including asphaltene and resin, and their possible interactions with two families of ILs, namely pyridinium and imidazolium, on the IFT of crude oil/aqueous solutions, both in the presence and absence of MgCl2. To the best of our knowledge, the effect of crude oil type on the IFT of crude oil/aqueous solution containing salts and IL has not been ever investigated. Accordingly, IFTs of light, medium and... 

    Investigation and visualization of surfactant effect on flow pattern and performance of pulsating heat pipe

    , Article Journal of Thermal Analysis and Calorimetry ; Volume 139, Issue 3 , 2020 , Pages 2099-2107 Gandomkar, A ; Kalan, K ; Vandadi, M ; Shafii, M. B ; Saidi, M. H ; Sharif University of Technology
    Springer Netherlands  2020
    Pulsating heat pipes (PHPs) are one of the new devices used for cooling in several applications such as electronic and aerospace systems. Their low cost, effectiveness at various conditions, being equipped for passive energy conversion, and well distribution of temperature compared to conventional heat pipes are among the reasons of their popularity. To investigate the effect of surface tension of the working fluid on the behavior of PHPs, a copper heat pipe is fabricated with inner and outer diameters of 2 mm and 4 mm, respectively. Five different concentrations of cetrimonium bromide (C-Tab) surfactant are dissolved in water and are tested with a filling ratio of 50% (± 1%). A piece of... 

    Investigating the synergic effects of chemical surfactant (SDBS) and biosurfactant produced by bacterium (Enterobacter cloacae) on IFT reduction and wettability alteration during MEOR process

    , Article Journal of Molecular Liquids ; Volume 256 , 2018 , Pages 277-285 ; 01677322 (ISSN) Hajibagheri, F ; Hashemi, A ; Lashkarbolooki, M ; Ayatollahi, S ; Sharif University of Technology
    Elsevier B.V  2018
    In the current study, a novel approach which takes into account the effectiveness of both convectional surfactants and biosurfactants was investigated. The biosurfactant produced by Enterobacter cloacae strain was utilized concomitant with conventional surfactant (sodium dodecyl benzene sulfonate (SDBS)) to evaluate its capability to reduce the SDBS adsorption on rock surface (biosurfactant acts as sacrificial agent) or synergistically enhance the effectiveness of the SDBS. In this regard, the wettability alteration and interfacial tension (IFT) measurements and calculation of spreading coefficient were performed considering two different scenarios. In the first scenario, SDBS was added to... 

    Investigating the efficiency of MEOR processes using Enterobacter cloacae and Bacillus stearothermophilus SUCPM#14 (biosurfactant-producing strains) in carbonated reservoirs

    , Article Journal of Petroleum Science and Engineering ; Volume 113 , January , 2014 , Pages 46-53 ; ISSN: 09204105 Sarafzadeh, P ; Niazi, A ; Oboodi, V ; Ravanbakhsh, M ; Hezave, A. Z ; Ayatollahi, S ; Raeissi, S ; Sharif University of Technology
    Microbial enhanced oil recovery (MEOR) process is divided into two main categories, namely in-situ and ex-situ techniques. It utilizes reservoir microorganisms or specially selected bacteria to use their metabolites for more oil recovery from depleted oil reservoirs. In the present study, the potential of two biosurfactant-producing strains of Enterobacter cloacae and Bacillus stearothermophilus SUCPM#14 were investigated on tertiary oil recovery efficiency in carbonated cores using different designed injection protocols. The required operational time, process cost and proper selection of bacterial formulation during the MEOR process were the main objectives of this study. The results of... 

    Investigating the effects of pH, surfactant and ionic strength on the stability of alumina/water nanofluids using DLVO theory

    , Article Journal of Thermal Analysis and Calorimetry ; 2018 ; 13886150 (ISSN) Zareei, M ; Yoozbashizadeh, H ; Madaah Hosseini, H. R ; Sharif University of Technology
    Springer Netherlands  2018
    Alumina nanofluids are one of the most useful nanofluids. In order to evaluate the colloidal behavior of nanoparticles in alumina/water nanofluid, the influence of effective factors such as pH, ionic strength and surfactants, was studied. Zeta potential, particle size and turbidity change of each nanofluid was investigated. According to the results for 0.05, 0.1 and 0.2 mass% nanofluid, point of zero charge was obtained at pH values of 9.5, 10.2 and 10.5, respectively. The highest nanofluid stability occurred at pH 4 and its lowest was at pH 10. The anionic surfactant had a greater effect on the stability in compared with cationic and nonionic surfactants. By increasing in ionic strength,...