Search for: surface-active-agents
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    Azo dye removal via surfactant-assisted polyvinylidene fluoride membrane

    , Article Environmental Health Engineering and Management ; Volume 8, Issue 1 , 2021 , Pages 25-32 ; 24233765 (ISSN) Darbandi, F ; Mousavi, A ; Bagheri Lotfabad, T ; Heydarinasab, A ; Yaghmaei, S ; Sharif University of Technology
    Kerman University of Medical Sciences  2021
    Background: Recently, concerns have been raised regarding the environmental and public health safety of azo dyes, the most widely used synthetic dyes. The membrane technique has been introduced as one of the efficient methods for dye removal treatments. Polyvinylidene fluoride (PVDF) membrane manipulated by surfactants was studied for removal of the azo dye, carmoisine. Methods: PVDF membrane was prepared via non-solvent-induced phase separation (NIPS) and used to remove the azo dye, carmoisine. Three nonionic surfactants including Tween 20, Tween 60, and Tween 80 were used individually as additives in casting solutions to improve PVDF membrane properties. Results: Fourier-transform infrared... 

    Studying the Mechanistic Behavior of Heavy Oil Displacement Using a Group of Alkalis and Surfactant Mixtures

    , Article Chemical Engineering Communications ; Vol. 202, issue. 3 , May , 2015 , p. 366-374 ; ISSN: 00986445 Dehghan, A. A ; Jadaly, A ; Masihi, M ; Ayatollahi, S ; Sharif University of Technology
    In this study, a mixture-based sulfonate-based surfactant with a novel formula capable of functioning in real oil reservoir conditions was prepared and some microscopic parameters, like its compatibility state, emulsion behavior, interfacial tension, and temperature dependency in the presence of a heavy oil sample, and two of the most popular alkalis were analyzed; then the results were compared with those of a commercial sulfate-based surfactant. The designed surfactant provided an optimum three-phase region in relatively high salinity media; however, its optimum value decreased when adding any alkaline materials; this trend was reversed for the solutions made with the sulfate-based... 

    Studying the mechanistic behavior of heavy oil displacement using a group of alkalis and surfactant mixtures

    , Article Chemical Engineering Communications ; Volume 202, Issue 3 , 2015 , Pages 366-374 ; 00986445 (ISSN) Dehghan, A. A ; Jadaly, A ; Masihi, M ; Ayatollahi, S ; Sharif University of Technology
    Taylor and Francis Ltd  2015
    In this study, a mixture-based sulfonate-based surfactant with a novel formula capable of functioning in real oil reservoir conditions was prepared and some microscopic parameters, like its compatibility state, emulsion behavior, interfacial tension, and temperature dependency in the presence of a heavy oil sample, and two of the most popular alkalis were analyzed; then the results were compared with those of a commercial sulfate-based surfactant. The designed surfactant provided an optimum three-phase region in relatively high salinity media; however, its optimum value decreased when adding any alkaline materials; this trend was reversed for the solutions made with the sulfate-based... 

    Inferential closed-loop control of particle size distribution for styrene emulsion polymerization

    , Article Chemical Engineering Science ; Volume 63, Issue 9 , 2008 , Pages 2378-2390 ; 00092509 (ISSN) Abedini, H ; Shahrokhi, M ; Sharif University of Technology
    In this work, a new control strategy for controlling the particle size distribution (PSD) in emulsion polymerization has been proposed. It is shown that the desired PSD can be achieved by controlling the free surfactant concentration which in turn can be done by manipulating the surfactant feed rate. Simulation results show that the closed-loop control of free surfactant concentration results in a better control of PSD compared to open-loop control strategy, in presence of model mismatch and disturbances. Since the on-line measuring of ionic free surfactant concentration is difficult, conductivity which is related to it is measured instead and used for control purposes. The closed-loop... 

    Electrodeposition of aluminum from molten AlCl3-NaCl-KCl mixture

    , Article Journal of Applied Electrochemistry ; Volume 36, Issue 10 , 2006 , Pages 1169-1173 ; 0021891X (ISSN) Jafarian, M ; Mahjani, M.G ; Gobal, F ; Danaee, I ; Sharif University of Technology
    Electrochemical deposition of aluminum from basic and acidic molten NaCl-KCl-AlCl3 mixture on a graphite electrode at 140 °C was studied by voltammetry, chronopotentiometry and constant current deposition. The deposition of aluminum was found to proceed via a nucleation/growth mechanism in basic melt, while it was found to be diffusion controlled in acidic melt. The diffusion coefficient calculated for Al2Cl- 7 ions in acidic melt by voltammetry was in agreement with the deductions of voltammetry. The morphology of the aluminum deposits was examined using a metallographic microscope and by SEM. It was shown that, depending on the current density (c.d.) and AlCl3 concentration (acidic or... 

    The effect of addition of Tiron as a surfactant on the microstructure of chemically deposited zinc oxide

    , Article Materials Science and Engineering B: Solid-State Materials for Advanced Technology ; Volume 128, Issue 1-3 , 2006 , Pages 53-57 ; 09215107 (ISSN) Sadrnezhaad, S. K ; Vaezi, M. R ; Sharif University of Technology
    The effect of one of the surfactants such as Tiron, a compound based on the benzene molecule, on the morphology and chemical composition of zinc oxide deposits, produced from a zinc complex solution using two-stage chemical deposition (TSCD) technique, has been investigated. TSCD technique is a novel and simple chemical route for the deposition of ZnO film from aqueous solution. Zinc oxide films deposited on high purity alumina (HPA) as a substrate. The results show that the addition of Tiron changes the surface morphology and causes to form the fine-grained structure. With a dense and nodular-shape appearance, the film produced from the precursor of zinc complex-containing Tiron, is... 

    Synthesis of SBR/PMMA core/shell latices: the role of initiator and surfactant on particle morphology and instability performance

    , Article Journal of Applied Polymer Science ; Volume 105, Issue 3 , 2007 , Pages 1412-1419 ; 00218995 (ISSN) Moghbeli, M. R ; Mohammadi, N ; Bagheri, R ; Sharif University of Technology
    Poly(butadiene-stat-styrene)/poly(methylmetacrylate), SBR/PMMA, structural latices were synthesized by using equal moles of different kinds of surfactants: anionic, nonionic, and anionic/nonionic mixture in a two-stage emulsion polymerization. The results indicate that the application of anionic surfactants for the first stage, accompanying sodium persulfate initiator, KPS, for both stages led to core/shell and raspberry morphologies depended upon the hydrophilic lipophilic balance (HLB) of the surfactant. On the other hand, a core/shell structure was observed for structural latices which were synthesized via application of nonionic or anionic/non-ionic mixed surfactants along with... 

    Comparison and modification of models in production of biosurfactant for Paenibacillus alvei and Bacillus mycoides and its effect on MEOR efficiency

    , Article Journal of Petroleum Science and Engineering ; Volume 128 , April , 2015 , Pages 177-183 ; 09204105 (ISSN) Najafi, A. R ; Roostaazad, R ; Soleimani, M ; Arabian, D ; Moazed, M. T ; Rahimpour, M. R ; Mazinani, S ; Sharif University of Technology
    Elsevier  2015
    Biosurfactant production from two indigenous consortia has already been investigated in two previous studies. In this study, comparison and modification of those models for having as much biosurfactant as possible was conducted. After characterization of bacteria by biochemical tests and 16S ribotyping, a fully modification on the final models was presented. Response surface methodology has the ability to investigate the liability of the parameters and models by the help of Desirability mode and R2 coefficient in Design Expert software. Our models in the previous works follow the style of (y=f(A,B,. . .)) and two Desirability of 0.968 and 0.996 for Paenibacillus alvei ARN63 and Bacillus... 

    Preparation and characterization of ZnO nanoparticles by a novel sol-gel route

    , Article Materials Letters ; Volume 61, Issue 14-15 , 2007 , Pages 3265-3268 ; 0167577X (ISSN) Vafaee, M ; Sasani Ghamsari, M ; Sharif University of Technology
    In this study, ZnO nanoparticles with 3 to 4 nm size and spherical shape have been prepared. For the first time, TEA (triethanolamine) as a surfactant has been used for the preparation of ZnO nanoparticles. The best concentration of each component was adjusted through comparison between different sol absorption spectra. The best sol regarding its optical property was subjected to analysis by photoluminescence spectroscopy. TEM micrograph and electron diffraction pattern of these particles were obtained to represent the morphology and crystalline phase of the particles, respectively. Experimental results have shown that the prepared zinc oxide nanoparticles by this method have higher... 

    A machine learning framework for predicting entrapment efficiency in niosomal particles

    , Article International Journal of Pharmaceutics ; Volume 627 , 2022 ; 03785173 (ISSN) Kashani Asadi Jafari, F ; Aftab, A ; Ghaemmaghami, S ; Sharif University of Technology
    Elsevier B.V  2022
    Niosomes are vesicles formed mostly by nonionic surfactant and cholesterol incorporation as an excipient. The drug entrapment efficiency of niosomal vesicles is particularly important and depends on many parameters. Changing the effective parameters to have maximum entrapment efficiency in the laboratory is time-consuming and costly. In this study, a machine learning framework was proposed to address these problems. In order to find the most critical parameter affecting the entrapment efficiency and its optimal value in a specific experiment, data were first extracted from articles of the last decade using keywords of niosome and thin-film hydration method. Then, deep neural network (DNN),... 

    Controlled growth of hollow polyaniline structures: From nanotubes to microspheres

    , Article Polymer (United Kingdom) ; Volume 54, Issue 21 , 2013 , Pages 5586-5594 ; 00323861 (ISSN) Pirhady Tavandashti, N ; Ghorbani, M ; Shojaei, A ; Sharif University of Technology
    Homogeneous and fairly monosized microspherical structures of polyaniline has been synthesized using a simple soft template method with β-naphthalene sulfonic acid (β-NSA) as both the surfactant and dopant, and ammonium persulfate (APS) as the oxidant at 2-5 C. The morphology of PANI-NSA was successfully controlled from nanotubes to microsphere, by changing the synthesis conditions (i.e. pH, the concentration of surfactant and monomer, and temperature). Some mechanistic aspects of the formation of nanotubes and hollow spheres have been discussed precisely based on SEM, TEM, DLS, FTIR and UV-visible results. Moreover, synthesis was performed under acidic environment to obtain further... 

    Adaptive neural fuzzy inference (ANFI) modeling technique for production of marine biosurfactant

    , Article Proceedings of the ASME Design Engineering Technical Conference ; Volume 2, Issue PARTS A AND B , 2012 , Pages 47-52 ; 9780791845011 (ISBN) Abbasi, A. A ; Ahmadian, M. T ; Sharif University of Technology
    In this study; a Sugeno type ANFI model which describes the relationship between the bio surfactant concentration as a model output and the critical medium components as its inputs has been constructed. The critical medium components are glucose, urea,SrCl2 and MgSo4 .The experimental data for training and testing capability of the model obtained by a statistical experimental design which have been captured from literatures. Six generalized bell shaped membership function have been selected for each of input variables and based on the training data ANFI model has been trained using the hybrid learning algorithm. The yielded biosurfactant concentration values from the model prediction shows... 

    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... 

    Preparation of sorbitan stearate

    , Article 2nd International Multi-Conference on Engineering and Technological Innovation, IMETI 2009, Orlando, FL, 10 July 2009 through 13 July 2009 ; Volume 1 , 2009 , Pages 81-85 ; 193427268X (ISBN); 9781934272688 (ISBN) Amin Mahalati, A. R ; Alemzadeh, I ; Vossoughi, M ; Inter-American Organization for Higher Education (IOHE); International Institute of Informatics and Systemics (IIIS); Journal of Systemics, Informatics and Cybernetics (JSCI) ; Sharif University of Technology
    International Institute of Informatics and Cybernetics, IIIC  2009
    The present paper relates to an improved method for making surfactant esters, especially sorbitan monostearate and tristearate. Sorbitan esters of fatty acid, stéarate are derived from a reaction between sorbitan and fatty acid. Method of sorbitan ester production needs addition of catalyst. Sorbitan stéarate production was studied using chemical catalyst. Two steps process leading sorbitan production under atmospheric and vacuum pressure with acid catalyst resulted dehydrated product at optimal residence time of 195 min at 180°C for atmospheric conditions and optimalresidence time of 150 min at the same temperature respectively. Sorbitan stearate production was studied by utilizing sorbitan... 

    The effects of bubble detachment shape on rising bubble hydrodynamics

    , Article Scientia Iranica ; Volume 26, Issue 3 C , 2019 , Pages 1546-1554 ; 10263098 (ISSN) Fayzi, P ; Bastani, D ; Lotfi, M ; Ghamangiz Khararoodi, M ; Sharif University of Technology
    Sharif University of Technology  2019
    Local velocities and aspect ratios of rising bubbles were measured to investigate the effects of bubble detachment shape on rising bubble hydrodynamics. Two types of capillary were employed to generate bubbles of identical volume: one glassy nozzle aligned vertically and the other stainless steel needle aligned horizontally. Horizontally injected bubbles have a spherical initial shape, and their values of aspect ratio slightly fluctuate around unity. However, vertically injected bubbles have a surface-stretched initial shape, and their values of aspect ratios decrease sharply from 1.1 to 0.65. There is a notable correspondence between the variation of local velocities and aspect ratios that... 

    Experimental investigation of the effects of surfactants on the mass transfer in liquid-liquid extraction equipment

    , Article 2007 5th Joint ASME/JSME Fluids Engineering Summer Conference, FEDSM 2007, San Diego, CA, 30 July 2007 through 2 August 2007 ; Volume 2 FORA, Issue PART A , 2007 , Pages 239-244 ; 0791842886 (ISBN); 9780791842881 (ISBN) Haghdoost, A ; Shah Alami, M ; Mansouri, H ; Sharif University of Technology
    Mass transfer rates to the drops in liquid-liquid extraction equipment are often likely to be reduced by the presence of surface active contaminants. This reduction in mass transfer is said to be due to a reduction in terminal velocity, and to changes in pattern of internal circulation. A single-drop extraction apparatus was used to investigate the dependency of mass transfer coefficient on the amount of surfactant added in a system of n-butanol/succinic acid/water. Three types of surfactants, SDS, DTMAC and Triton X-100, were used to study their effects on the inhibition of mass transfer in liquid-liquid extraction. The effect of surfactants concentration on extraction percentage, overall... 

    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... 

    Cobalt salophen-modified carbon-paste electrode incorporating a cationic surfactant for simultaneous voltammetric detection of ascorbic acid and dopamine

    , Article Sensors and Actuators, B: Chemical ; Volume 121, Issue 2 , 2007 , Pages 530-537 ; 09254005 (ISSN) Shahrokhian, S ; Zare Mehrjardi, H. R ; Sharif University of Technology
    A carbon-paste electrode (CPE) is modified by incorporating cobalt-5-nitrosalophen (CoNSal) and tetraoctylammonium bromide (TOAB). The mechanism of electrocatalytic oxidation of dopamine (DA) and ascorbic acid (AA) at the surface of the CoNSal-modified CPE containing various percents of TOAB is thoroughly investigated by cyclic and differential pulse voltammetry. In solutions of pH 5.0, in which all studies are performed, DA exists as the positively charged species whereas AA is mainly as the neutral form. Therefore, the favorable ionic interaction (electrostatic repulsion) between the cationic form of DA and the cationic surfactant (TOA+) caused increasing the overvoltage for DA and... 

    Study and optimization of Amino Acid Extraction by emulsion Liquid Membrane

    , Article CHISA 2006 - 17th International Congress of Chemical and Process Engineering, Prague, 27 August 2006 through 31 August 2006 ; 2006 ; 8086059456 (ISBN); 9788086059457 (ISBN) Mohagheghe, E ; Vosoughi, M ; Alemzadeh, I ; Hexion Specialty Chemicals; Mitsubishi Chemical Corporation; CS Cabot; Zentiva; BorsodChem MCHZ ; Sharif University of Technology
    A batch extraction of an essential amino acid, Phenylalanine, from an aqueous solution of different concentrations by an Emulsion Liquid Membrane (ELM) was developed using D2EHPA as a cationic carrier, Span 80 as the surfactant, paraffin and kerosene as the diluents, and HCl as the internal electrolyte. All effective parameters such as pH of initial aqueous external phase, electrolyte concentration in aqueous internal phase, carrier and surfactant concentration in emulsion, volume ratio of the organic to aqueous internal phase (Roi), volume ratio of the W/O emulsion to aqueous external phase (Rew) and time were examined and optimized using Taguchi method which was the first time of... 

    Photo-induced CdS nanoparticles growth

    , Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 30, Issue 1-2 , 2005 , Pages 114-119 ; 13869477 (ISSN) Taghavinia, N ; Azam Iraji Zad ; Mahdavi, S. M ; Reza-Esmaili, M ; Sharif University of Technology
    A photochemical approach on the size control of CdS nanoparticles is presented. CdS nanoparticles were grown using the photo-induced reaction of sodium thiosulfate with Cadmium sulfate, in the absence of any surfactant. Particles of 5.5-11 nm were obtained by changing the illumination time. The dark growth of nanoparticles was negligible, however we found by optical scattering measurements that a ripening phenomenon occurs and the size of nanoparticles slightly increases with time. © 2005 Elsevier B.V. All rights reserved