Search for: surface-active-agents
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    A photochemical method for controlling the size of CdS nanoparticles

    , Article Nanotechnology ; Volume 16, Issue 2 , 2005 , Pages 334-338 ; 09574484 (ISSN) Marandi, M ; Taghavinia, N ; Iraji Zad, A ; Mahdavi, S. M ; Sharif University of Technology
    The optical and electrical properties of semiconductor nanoparticles are strongly dependent on their size. A flexible control of the size of the nanoparticles is of interest for tuning their properties for different applications. Here we use a coupled method to control the size of CdS nanoparticles. The method involves the photochemical growth of CdS nanoparticles together with the use of a capping agent as an inhibiting factor. CdS nanoparticles were formed through a photoinduced reaction of CdSO4 and Na2S2O3 in an aqueous solution. Mercaptoethanol (C2H6OS) was used as the capping agent, and we investigated the effect of illumination time, illumination intensity and the concentration of... 

    Studies of the rate of water evaporation through adsorption layers using drop shape analysis tensiometry

    , Article Journal of Colloid and Interface Science ; Volume 308, Issue 1 , 2007 , Pages 249-253 ; 00219797 (ISSN) Fainerman, V. B ; Makievski, A. V ; Krägel, J ; Javadi, A ; Miller, R ; Sharif University of Technology
    With modified measuring procedure and measuring cell design in the drop profile tensiometer PAT, it became possible to study the rate of water evaporation through adsorbed or spread surface layers. This method was employed to measure the rate of water evaporation from drops covered by adsorbed layers of some proteins and surfactants, in particular n-dodecanol. It was shown that the formation of dense (double or condensed) adsorbed layers of protein and the formation of 2D-condensed n-dodecanol layer decrease the water evaporation rate by 20-25% as compared with pure water. At the same time, the adsorbed layers of ordinary surfactants (sodium dodecyl sulfate and nonionic ethoxylated... 

    Core flooding tests to investigate the effects of IFT reduction and wettability alteration on oil recovery during MEOR process in an Iranian oil reservoir

    , Article Applied Microbiology and Biotechnology ; Volume 97, Issue 13 , July , 2013 , Pages 5979-5991 ; 01757598 (ISSN) Rabiei, A ; Sharifinik, M ; Niazi, A ; Hashemi, A ; Ayatollahi, S ; Sharif University of Technology
    Microbial enhanced oil recovery (MEOR) refers to the process of using bacterial activities for more oil recovery from oil reservoirs mainly by interfacial tension reduction and wettability alteration mechanisms. Investigating the impact of these two mechanisms on enhanced oil recovery during MEOR process is the main objective of this work. Different analytical methods such as oil spreading and surface activity measurements were utilized to screen the biosurfactant-producing bacteria isolated from the brine of a specific oil reservoir located in the southwest of Iran. The isolates identified by 16S rDNA and biochemical analysis as Enterobacter cloacae (Persian Type Culture Collection (PTCC)... 

    Efficient biodegradation of naphthalene by a newly characterized indigenous achromobacter sp. FBHYA2 isolated from Tehran oil refinery complex

    , Article Water Science and Technology ; Volume 66, Issue 3 , March , 2012 , Pages 594-602 ; 02731223 (ISSN) Farjadfard, S ; Borghei, S. M ; Hassani, A. H ; Yakhchali, B ; Ardjmand, M ; Zeinali, M ; Sharif University of Technology
    IWA Pub  2012
    A bacterial strain, FBHYA2, capable of degrading naphthalene, was isolated from the American Petroleum Institute (API) separator of the Tehran Oil Refinery Complex (TORC). Strain FBHYA2 was identified as Achromobacter sp. based on physiological and biochemical characteristics and also phylogenetic similarity of 16S rRNA gene sequence. The optimal growth conditions for strain FBHYA2 were pH 6.0, 30°C and 1.0% NaCl. Strain FBHYA2 can utilize naphthalene as the sole source of carbon and energy and was able to degrade naphthalene aerobically very fast, 48 h for 96% removal at 500 mg/L concentration. The physiological response of Achromobacter sp., FBHYA2 to several hydrophobic chemicals... 

    Interactive optimization of biosurfactant production by Paenibacillus alvei ARN63 isolated from an Iranian oil well

    , Article Colloids and Surfaces B: Biointerfaces ; Volume 82, Issue 1 , 2011 , Pages 33-39 ; 09277765 (ISSN) Najafi, A. R ; Rahimpour, M. R ; Jahanmiri, A. H ; Roostaazad, R ; Arabian, D ; Soleimani, M ; Jamshidnejad, Z ; Sharif University of Technology
    The potential of an indigenous bacterial strain isolated from an Iranian oil field for the production of biosurfactant was investigated in this study. After isolation, the bacterium was characterized to be Paenibacillus alvei by biochemical tests and 16S ribotyping. The biosurfactant, which was produced by this bacterium, was able to lower the surface tension of media to 35. mN/m. Accordingly, thin layer chromatography (TLC) and FT-IR has been carried out to determine compositional analysis of the produced biosurfactant. After all the tests related to characterization of the biosurfactant produced by the isolated bacterium, it was characterized as lipopeptide derivative. The combination of... 

    Two schemes for production of biosurfactant from Pseudomonas aeruginosa MR01: Applying residues from soybean oil industry and silica sol–gel immobilized cells

    , Article Colloids and Surfaces B: Biointerfaces ; Volume 152 , 2017 , Pages 159-168 ; 09277765 (ISSN) Bagheri Lotfabad, T ; Ebadipour, N ; Roostaazad, R ; Partovi, M ; Bahmaei, M ; Sharif University of Technology
    Elsevier B.V  2017
    Rhamnolipids are the most common biosurfactants and P. aeruginosa strains are the most frequently studied microorganisms for the production of rhamnolipids. Eco-friendly advantages and promising applications of rhamnolipids in various industries are the major reasons for pursuing the economic production of these biosurfactants. This study shows that cultivation of P. aeruginosa MR01 in medium contained inexpensive soybean oil refinery wastes which exhibited similar levels and homologues of rhamnolipids. Mass spectrometry indicated that the Rha-C10-C10 and Rha-Rha-C10-C10 constitute the main rhamnolipids in different cultures of MR01 including one of oil carbon source analogues. Moreover,... 

    Phase behavior and interfacial tension evaluation of a newly designed surfactant on heavy oil displacement efficiency; effects of salinity, wettability, and capillary pressure

    , Article Fluid Phase Equilibria ; Vol. 396, issue , June , 2015 , p. 20-27 ; ISSN: 03783812 Dehghan, A. A ; Masihi, M ; Ayatollahi, S ; Sharif University of Technology
    This work aims to discuss the results of wide ranges of laboratory investigations to evaluate the performance of a newly-formulated surfactant for heavy oil reservoirs in order to improve the microscopic sweep efficiency after water flooding processes. In the first part, the specific behavior of the formulated surfactant including its salinity tolerance, interfacial tension, and optimum performance window was determined. Then, the application of surfactant solutions in real sandstone reservoir rocks was assessed for both oil-wet and water-wet cases. Besides, the effect of changing the capillary and viscous forces and interfacial tension on the residual phase saturations were characterized.... 

    Bubble in flow field: A new experimental protocol for investigating dynamic adsorption layers by using capillary pressure tensiometry

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Vol. 460, issue , 2014 , p. 369-376 Lotfi, M ; Bastani, D ; Ulaganathan, V ; Miller, R ; Javadi, A ; Sharif University of Technology
    For many years the model of a dynamic adsorption layer (DAL) is well established as explanation for the behavior of rising bubbles in surfactant solutions. This model explains the velocity profile and the evolution of the shape of a rising bubble based on the hypothesis of the balance between the drag force and the structure of the adsorbed layer governed by Marangoni convection. However, direct measurements of interfacial properties of the bubble during rising are a real challenge. Here we present a new experimental protocol called "bubble in flow field" suitable for direct measurements of dynamic interfacial properties of a bubble surface using the capillary pressure tensiometry under... 

    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... 

    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... 

    Statistical screening of medium components for recombinant production of Pseudomonas aeruginosa ATCC 9027 rhamnolipids by nonpathogenic cell factory pseudomonas putida KT2440

    , Article Molecular Biotechnology ; Vol. 56, issue. 2 , 2014 , p. 175-191 Setoodeh, P ; Jahanmiri, A ; Eslamloueyan, R ; Niazi, A ; Ayatollahi, S. S ; Aram, F ; Mahmoodi, M ; Hortamani, A ; Sharif University of Technology
    Rhamnolipids (RLs) produced by the opportunistic human pathogen Pseudomonas aeruginosa are considered as potential candidates for the next generation of surfactants. Large-scale production of RLs depends on progress in strain engineering, medium design, operating strategies, and purification procedures. In this work, the rhlAB genes extracted from a mono-RLs-producing strain of P. aeruginosa (ATCC 9027) were introduced to an appropriate safety host Pseudomonas putida KT2440. The capability of the recombinant strain was evaluated in various media. As a prerequisite for optimal medium design, a set of 32 experiments was performed in two steps for screening a number of macro-nutritional... 

    Highly efficient hydroxyapatite/TiO2 composites covered by silver halides as E. coli disinfectant under visible light and dark media

    , Article Photochemical and Photobiological Sciences ; Volume 12, Issue 10 , 2013 , Pages 1787-1794 ; 1474905X (ISSN) Azimzadehirani, M ; Elahifard, M ; Haghighi, S ; Gholami, M ; Sharif University of Technology
    TiO2-based photocatalysts are seen as the most common agents for the photodegradation of bacteria. In this study, AgCl/TiO2, hydroxyapatite(Hp)/AgCl/TiO2, AgI/TiO2, and Hp/AgI/TiO2 were prepared by the deposition-precipitation method on P25 TiO2 nanoparticles and were characterized by XRD, SEM, FT-IR, EDX and BET methods. The prepared composites showed high efficiency for the inactivation of Escherichia coli (E. coli) bacteria under visible light and in dark media with different catalyst amounts of 12 and 24 mg, respectively. In less than 30 min, AgI/TiO2, prepared by the combination of cationic surfactant and PVPI2, disinfected 1 × 107 colony-forming units of E. coli completely. However,... 

    Thermal conductivity of mixed nanofluids under controlled pH conditions

    , Article International Journal of Thermal Sciences ; Volume 74 , 2013 , Pages 63-71 ; 12900729 (ISSN) Iranidokht, V ; Hamian, S ; Mohammadi, N ; Shafii, M. B ; Sharif University of Technology
    Just a few investigations have been conducted to study the mixed nanofluids(MNs), which contain more than one type of nanoparticles, despite considerable advances in the field of nanofluids thermal conductivity. In present research, by combining different volume fractions of various nanoparticles, the variation of mixed nanofluids thermal conductivity was considered. The mentioned nanofluids have different fabrication cost. First, the effect of each specific nanoparticle presence in the base fluid on the thermal conductivity of nanofluid was surveyed both experimentally and theoretically. Then, the thermal conductivities of two MNs, one consisted of a metallic nanoparticle (high thermal... 

    Application of biosurfactants to wettability alteration and IFT reduction in enhanced oil recovery from oil-wet carbonates

    , Article Petroleum Science and Technology ; Volume 31, Issue 12 , Jul , 2013 , Pages 1259-1267 ; 10916466 (ISSN) Biria, D ; Maghsoudi, E ; Roostaazad, R ; Sharif University of Technology
    To obtain potentially applicable microorganisms to an effective in situ microbial enhanced oil recovery operation, bacteria that were compatible with the harsh conditions of a petroleum reservoir were isolated from a crude oil sample. The application of an oil spreading technique showed that all of the isolates were capable of producing biosurfactants from both the glucose and crude oil as carbon sources. The secreted biosurfactants could at least reduce the surface tension 20 mN/m and for one of the isolates; the surface tension value dropped below 40 mN/m. In addition, the contact angle measurements revealed that the produced biosurfactants could effectively alter the wettability of the... 

    Size-controlled synthesis of superparamagnetic iron oxide nanoparticles and their surface coating by gold for biomedical applications

    , Article Journal of Magnetism and Magnetic Materials ; Volume 324, Issue 23 , November , 2012 , Pages 3997-4005 ; 03048853 (ISSN) Maleki, H ; Simchi, A ; Imani, M ; Costa, B. F. O ; Sharif University of Technology
    The size mono-dispersity, saturation magnetization, and surface chemistry of magnetic nanoparticles (NPs) are recognized as critical factors for efficient biomedical applications. Here, we performed modified water-in-oil inverse nano-emulsion procedure for preparation of stable colloidal superparamagnetic iron oxide NPs (SPIONs) with high saturation magnetization. To achieve mono-dispersed SPIONs, optimization process was probed on several important factors including molar ratio of iron salts [Fe 3 and Fe 2], the concentration of ammonium hydroxide as reducing agent, and molar ratio of water to surfactant. The biocompatibility of the obtained NPs, at various concentrations, was evaluated via... 

    The effect of cationic and anionic surfactants on the nanostructure and magnetic properties of Yttrium Iron Garnet (YIG) synthesized by a sol-gel auto combustion method

    , Article Russian Journal of Non-Ferrous Metals ; Volume 53, Issue 4 , 2012 , Pages 308-314 ; 10678212 (ISSN) Emami, S ; Madaah Hosseini, H. R ; Dolati, A ; Sharif University of Technology
    Yttrium Iron Garnet (YIG) powders were synthesized by a sol-gel auto-combustion method using cationic and anionic surfactants with different values and different calcination times and temperatures. The final products were characterized by DTA/TG, XRD, TEM and VSM techniques. The results showed a decrease in calcination temperature and crystallite size in the presence of a cationic surfactant, while no significant effect was observed using an anionic surfactant. Magnetic properties of YIG powders were improved as an optimum value of cationic surfactant was used  

    Experimental investigation of asp flooding in fractured heavy oil five-spot systems

    , Article 74th European Association of Geoscientists and Engineers Conference and Exhibition 2012 Incorporating SPE EUROPEC 2012: Responsibly Securing Natural Resources, 4 June 2012 through 7 June 2012 ; 2012 , Pages 3924-3928 ; 9781629937908 (ISBN) Sedaghat, M. H ; Ghazanfari, M. H ; Masihi, M ; Rashtchian, D ; Sharif University of Technology
    European Association of Geoscientists and Engineers, EAGE  2012
    Although alkaline-surfactant-polymer flooding is proved to be efficient for oil recovery from heavy oil reservoirs, the displacements mechanism/efficiency of this process in fractured systems needs to more discussion, especially in five-spot patterns. In this work, several ASP flooding test were performed on fractured micromodels which were initially saturated with heavy oil at constant flow rate and different fracture geometrical characteristics conditions. The ASP solutions are constituted from 5 polymers i.e. four synthetic polymers include three hydrolyzed polyacrylamide with different molecular weight as well as a non-hydrolyzed polyacrylamide and a biopolymer, 2 surfactants i.e. a... 

    Electrodeposition of Ni/WC nano composite in sulfate solution

    , Article Materials Chemistry and Physics ; Volume 129, Issue 3 , 2011 , Pages 746-750 ; 02540584 (ISSN) Mohajeri, S ; Dolati, A ; Rezagholibeiki, S ; Sharif University of Technology
    Metal matrix composite coatings have gained great attention due to their exclusive properties. They have shown the properties of a metallic host material modified by addition of a second phase. In electrodeposition of Ni/WC nano composite, nickel was deposited on the substrates by DC electrodeposition in Watt's based bath containing nickel sulfate, nickel chloride, boric acid and sodium dodecyl sulfate. WC content in the coating was determined by different parameters such as current density, powder content and surfactant amount. Mechanism of electrodeposition was analyzed by cyclic voltammetry and was confirmed by Guglielmi model. Surface morphology was studied by scanning electron... 

    Enhancement of fungal delignification of rice straw by Trichoderma viride sp. to improve its saccharification

    , Article Biochemical Engineering Journal ; Volume 101 , September , 2015 , Pages 77-84 ; 1369703X (ISSN) Ghorbani, F ; Karimi, M ; Biria, D ; Kariminia, H. R ; Jeihanipour, A ; Sharif University of Technology
    Elsevier  2015
    Fungal delignification can be considered as a feasible process to pre-treat lignocellulosic biomass in biofuel production, if its performance is improved in terms of efficiency thorough a few modifications. In this study, Trichoderma viride was utilized to investigate the effect of wet-milling, addition of surfactant (Tween 80) and optimization of operating factors such as temperature, biomass to liquid medium ratio and glucose concentration on biodelignification of rice straw. Next, the enzymatic hydrolysis of pretreated biomass was studied at various pretreatment times. Results revealed that the wet milling and addition of surfactant increases the lignin removal about 15% and 11%,... 

    Rheology, stability and filtration characteristics of colloidal gas aphron fluids: role of surfactant and polymer type

    , Article Journal of Natural Gas Science and Engineering ; Volume 26 , September , 2015 , Pages 895-906 ; 18755100 (ISSN) Tabzar, A ; Arabloo, M ; Ghazanfari, M. H ; Sharif University of Technology
    Elsevier  2015
    Colloidal Gas Aphron (CGA) are finding increasing application in fields of science and engineering because of their distinctive characteristic. As interest in the application of CGA based fluids grows and in order to select the best procedure for using them in successful petroleum engineering operations, there is a need to gain a better understanding of the factors that affect their properties and behavior. This article discusses the rheological characterization, stability analysis and filtration properties of CGA based fluids for three bio-polymers and two ionic surfactant. The stability and filtration analysis were investigated with the static drain rate technique and API filtration tests,...