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    Dissociation of polar oil components in low salinity water and its impact on crude oil–brine interfacial interactions and physical properties

    , Article Petroleum Science ; 2018 ; 16725107 (ISSN) Mokhtari, R ; Ayatollahi, S ; Sharif University of Technology
    China University of Petroleum Beijing  2018
    Abstract
    Despite many efforts into the study of fluids interaction in low salinity water flooding, they are not probing the basics of transport phenomena between the involved phases. This work is aimed to bring new understanding of fluid–fluid interaction during low salinity water flooding through a series of organized experiments in which a crude oil sample with known properties was kept in contact with different brine solutions of various ionic strengths. Measuring brine pH, conductivity and crude oil viscosity and density for a period of 45 days illustrates the strong effect of the contact time and ionic strength on the dissociation of polar components and physical properties of the crude oil and... 

    Dissociation of polar oil components in low salinity water and its impact on crude oil–brine interfacial interactions and physical properties

    , Article Petroleum Science ; Volume 16, Issue 2 , 2019 , Pages 328-343 ; 16725107 (ISSN) Mokhtari, R ; Ayatollahi, S ; Sharif University of Technology
    China University of Petroleum Beijing  2019
    Abstract
    Despite many efforts into the study of fluids interaction in low salinity water flooding, they are not probing the basics of transport phenomena between the involved phases. This work is aimed to bring new understanding of fluid–fluid interaction during low salinity water flooding through a series of organized experiments in which a crude oil sample with known properties was kept in contact with different brine solutions of various ionic strengths. Measuring brine pH, conductivity and crude oil viscosity and density for a period of 45 days illustrates the strong effect of the contact time and ionic strength on the dissociation of polar components and physical properties of the crude oil and... 

    Foam stability and foam-oil interactions

    , Article Petroleum Science and Technology ; Vol. 32, issue. 15 , May , 2014 , p. 1843-1850 ; ISSN: 10916466 Rashed Rohani, M ; Ghotbi, C ; Badakhshan, A ; Sharif University of Technology
    Abstract
    Gas injection into reservoirs can be used to increase oil recovery. However, reservoir heterogeneity and high gas mobility reduce sweep efficiency and decrease recovery. Using foam can reduce gas mobility and therefore increase sweep efficiency. Foam is thermodynamically unstable, so it is important to predict the foam stability. In order to understand the influence of oil presence on foam stability, static experiments performed on foam by varying the type and amount of added oil and molecular weight of added alkane. Also static foam properties have been investigated by varying the surfactant concentration, ionic strength, composition of different salts in the sample, and addition of polymer... 

    Adsorption of silica nanoparticles onto calcite: Equilibrium, kinetic, thermodynamic and DLVO analysis

    , Article Chemical Engineering Journal ; Volume 281 , December , 2015 , Pages 334-344 ; 13858947 (ISSN) Dehghan Monfared, A ; Ghazanfari, M. H ; Jamialahmadi, M ; Helalizadeh, A ; Sharif University of Technology
    Elsevier  2015
    Abstract
    Recently, application of silica nanoparticles (SNP) for enhancing oil recovery during water flooding has been much attended. However, understanding how rock and nanoparticles (NP) interacts through adsorption onto the carbonate reservoir rocks is not well discussed. In this work, adsorption behavior of SNP onto the calcite had been characterized, through kinetic, equilibrium, thermodynamics and electrokinetic studies as well as interaction energy analysis by DLVO theory. Also, field emission scanning electron microscopy (FESEM) was utilized to visualize the adsorption process. It had been found that kinetic behavior of SNP-calcite system followed the pseudo-second order model. Equilibrium... 

    A simple shape-controlled synthesis of gold nanoparticles using nonionic surfactants

    , Article RSC Advances ; Volume 3, Issue 21 , 2013 , Pages 7726-7732 ; 20462069 (ISSN) Hormozi Nezhad, M. R ; Karami, P ; Robatjazi, H ; Sharif University of Technology
    2013
    Abstract
    Green and simple synthesis strategies have gained tremendous popularity for the production of anisotropically-shaped noble metallic nanoparticles. The long-term stability of the produced particles, the short timescale of the target reaction(s), as well as the use of non-toxic chemicals, are pivotal features of a useful green procedure. Herein we describe a simple and convenient wet-chemical approach to synthesize stable, non-toxic and water-soluble small gold nanotriangles (GNTs) and gold nanospheres (GNSs) in one step at room temperature, using Tween 20 and Tween 80, respectively. A high level of purity and monodispersity was obtained for the GNTs, in addition to an excellent colloidal... 

    New grafted nanosilica-based sorbent for needle trap extraction of polycyclic aromatic hydrocarbons from water samples followed by GC/MS

    , Article Chromatographia ; Volume 74, Issue 5-6 , September , 2011 , Pages 429-436 ; 00095893 (ISSN) Bagheri, H ; Roostaie, A ; Babanezhad, E ; Sharif University of Technology
    2011
    Abstract
    In this work, the preparation of a new grafted nanosilica-based sorbent was extensively investigated. An inexpensive modifier, cis-9-octadecenoic acid (oleic acid) was selected to be grafted on the surface of the nanosilica particles as the support. The grafting process was accurately confirmed by Fourier transform infra-red spectrometry (FT-IR). Applicability of the prepared sorbent was thoroughly examined by needle trap extraction (NTE) method. The grafted sorbent was dispersed in the appropriate solvent and carefully packed inside a steel needle. Feasibility of the method was completely examined using polycyclic aromatic hydrocarbons (PAHs), as model compounds. For extraction of analytes... 

    Synthesis and evaluation of pH and thermosensitive pectin-based superabsorbent hydrogel for oral drug delivery systems

    , Article Starch/Staerke ; Volume 61, Issue 3-4 , 2009 , Pages 161-172 ; 00389056 (ISSN) Pourjavadi, A ; Barzegar, S ; Sharif University of Technology
    2009
    Abstract
    The purpose of this study was to produce intelligent pectin-based superabsorbent polymers (SAP) to be used as pH- and thermosensitive carriers for the controlled delivery of non-steroidal anti-inflammatory drugs (NSAIDs). The superabsorbent formation was confirmed by Fourier transform infrared spectroscopic (FT-IR) and scanning electron microscopy (SEM). The effects of pH, ionic strength, temperature, porosity, particle size and levels of loaded drug on drug release profile in various surrounding media were investigated. Each sample was well characterized through swelling studies. The molecular weight between crosslinks (M̄C), crosslinking density (ve) polymer-solvent interaction parameter... 

    Experimental investigation of dynamic asphaltene adsorption on calcite packs: The impact of single and mixed-salt brine films

    , Article Canadian Journal of Chemical Engineering ; Volume 97, Issue 7 , 2019 , Pages 2028-2038 ; 00084034 (ISSN) Monjezi, R ; Ghotbi, C ; Jafari Behbahani, T ; Bakhshi, P ; Sharif University of Technology
    Wiley-Liss Inc  2019
    Abstract
    In this study, the dynamic adsorption of asphaltene on a calcite surface is investigated. This study investigates the effect of mixed-salt brines on asphaltene adsorption. The results of this work can facilitate the understanding of the complex wettability behaviour of carbonate reservoirs. All experiments were performed in porous media, which were sand-packs filled with calcite powder, to study the influence of the type and concentration of salt on adsorption. The experiments were conducted with asphaltene concentration of 500 mg/L for brines of NaCl, Na2SO4, and a mixture of the two at various ionic strengths. In addition, two tests were performed with an asphaltene concentration of 2000... 

    Experimental study on the influence of initial pH, ionic strength, and temperature on the selective adsorption of dyes onto nanodiamonds

    , Article Journal of Chemical and Engineering Data ; Volume 64, Issue 4 , 2019 , Pages 1508-1514 ; 00219568 (ISSN) ; https://pubs.acs.org/doi/abs/10.1021/acs.jced.8b01091 Molavi, H ; Pourghaderi, A ; Shojaei, A ; Sharif University of Technology
    American Chemical Society  2019
    Abstract
    In the current work, the performance of untreated nanodiamonds (UNDs) and thermally oxidized nanodiamonds (ONDs), as adsorbents for selective adsorption of methylene blue (MB) and methyl orange (MO) from aqueous media, was examined. The adsorption isotherm, initial pH, ionic strength, and thermodynamic study were investigated in batch experiments. The equilibrium adsorption data were analyzed by Langmuir and Freundlich isotherm models, which indicated that the isotherms were well fitted with the Langmuir model for both dyes. Thermodynamic parameters indicated that the adsorption operation was a feasible, spontaneous, and physisorption process in experimental conditions. Meanwhile, the... 

    Experimental study on the influence of initial pH, Ionic strength, and temperature on the selective adsorption of dyes onto nanodiamonds

    , Article Journal of Chemical and Engineering Data ; 2019 ; 00219568 (ISSN) Molavi, H ; Pourghaderi, A ; Shojaei, A ; Sharif University of Technology
    American Chemical Society  2019
    Abstract
    In the current work, the performance of untreated nanodiamonds (UNDs) and thermally oxidized nanodiamonds (ONDs), as adsorbents for selective adsorption of methylene blue (MB) and methyl orange (MO) from aqueous media, was examined. The adsorption isotherm, initial pH, ionic strength, and thermodynamic study were investigated in batch experiments. The equilibrium adsorption data were analyzed by Langmuir and Freundlich isotherm models, which indicated that the isotherms were well fitted with the Langmuir model for both dyes. Thermodynamic parameters indicated that the adsorption operation was a feasible, spontaneous, and physisorption process in experimental conditions. Meanwhile, the... 

    Experimental study on the influence of initial pH, ionic strength, and temperature on the selective adsorption of dyes onto nanodiamonds

    , Article Journal of Chemical and Engineering Data ; 2019 ; 00219568 (ISSN) Molavi, H ; Pourghaderi, A ; Shojaei, A ; Sharif University of Technology
    American Chemical Society  2019
    Abstract
    In the current work, the performance of untreated nanodiamonds (UNDs) and thermally oxidized nanodiamonds (ONDs), as adsorbents for selective adsorption of methylene blue (MB) and methyl orange (MO) from aqueous media, was examined. The adsorption isotherm, initial pH, ionic strength, and thermodynamic study were investigated in batch experiments. The equilibrium adsorption data were analyzed by Langmuir and Freundlich isotherm models, which indicated that the isotherms were well fitted with the Langmuir model for both dyes. Thermodynamic parameters indicated that the adsorption operation was a feasible, spontaneous, and physisorption process in experimental conditions. Meanwhile, the... 

    Evaluation of partial least-squares regression with multivariate analytical figures of merit for determination of 10 pesticides in milk

    , Article International Journal of Environmental Analytical Chemistry ; March , 2020 Koleini, F ; Balsini, P ; Parastar, H ; Sharif University of Technology
    Taylor and Francis Ltd  2020
    Abstract
    A multi-residue method using gas chromatography coupled with flame ionisation detector has been developed for simultaneous determination of 10 pesticides in milk. The methodology involved a sample clean-up procedure using ‘quick, easy, cheap, effective, rugged and safe’ followed by a preconcentration step based on dispersive liquid–liquid microextraction. In this regard, acetonitrile was added to the milk sample with specific pH and ionic strength, and the mixture was rigorously shaken. The extracts were centrifuged; then, the organic phase (acetonitrile) was transferred to a test tube and was mixed with deionised water. The mixture was sonicated and chloroform was added as an acceptor phase... 

    Sol-gel-based SPME and GC-MS for trace determination of geosmin in water and apple juice samples

    , Article Chromatographia ; Volume 66, Issue 9-10 , 2007 , Pages 779-783 ; 00095893 (ISSN) Bagheri, H ; Aghakhani, A ; EsHaghi, A ; Sharif University of Technology
    2007
    Abstract
    A headspace solid-phase microextraction (HS-SPME) method was developed for the trace determination of geosmin in water and apple juice samples. A poly(dimethylsiloxane) (PDMS) fiber was synthesized as coated fiber using sol-gel methodology. After performing the extraction in the headspace, the fiber was introduced directly into the injection port of a gas chromatography-mass spectrometry (GC-MS) using electron impact (EI) ionization mode. One-at-the-time optimization strategy was applied to investigate and optimize important extraction parameters such as extraction temperature and time, ionic strength, headspace volume, and desorption temperature and time. The analytical data exhibited an... 

    Multi-stimuli-responsive hydrogels and their medical applications

    , Article New Journal of Chemistry ; Volume 45, Issue 35 , 2021 , Pages 15705-15717 ; 11440546 (ISSN) Pourjavadi, A ; Heydarpour, R ; Tehrani, Z. M ; Sharif University of Technology
    Royal Society of Chemistry  2021
    Abstract
    The functionality of multi-stimuli-responsive hydrogels in physiological states is the reason for the increased attention of hydrogels nowadays. Multi-stimuli-responsive hydrogels exhibit tunable changes in swelling or mechanical properties in response to predetermined combinations of stimuli such as pH, temperature, ionic strength, electric field, magnetic field, light, chemical triggers, enzyme concentration, redox species, reactive oxygen species (ROS), and glucose levels. This review summarizes the recent advances in multi-stimuli-responsive hydrogels used in medical approaches. The first part of the review highlights the medical applications of polymer-based and supramolecular hydrogels... 

    Electrokinetic mixing and displacement of charged droplets in hydrogels

    , Article Transport in Porous Media ; Vol. 104, Issue. 3 , Jun , 2014 , pp. 469-499 ; ISSN: 01693913 Mohammadi, A ; Sharif University of Technology
    Abstract
    Mixing in droplets is an essential task in a variety of microfluidic systems. Inspired by electrokinetic mixing, electric field-induced hydrodynamic flow inside a charged droplet embedded in an unbounded polyelectrolyte hydrogel is investigated theoretically. In this study, the polyelectrolyte hydrogel is modeled as a soft, and electrically charged porous solid saturated with a salted Newtonian fluid, and the droplet is considered an incompressible Newtonian fluid. The droplet-hydrogel interface is modeled as a surface, which is located at the plane of shear, with the electrostatic potential ζ. The fluid inside the droplet attains a finite velocity owing to hydrodynamic coupling with the... 

    A highly thermal-resistant electrospun-based polyetherimide nanofibers coating for solid-phase microextraction Microextraction Techniques

    , Article Analytical and Bioanalytical Chemistry ; Vol. 406, issue. 8 , March , 2014 , p. 2141-2149 Bagheri, H ; Akbarinejad, A ; Aghakhani, A ; Sharif University of Technology
    Abstract
    A high-temperature-resisant solid-phase microextraction (SPME) fiber was prepared based on polyetherimide (PEI) by the electrospinning method. The PEI polymeric solution was converted to nanofibers using high voltages and directly coated on a stainless steel SPME needle. The scanning electron microscopy images of PEI coating showed fibers with diameter range of 500-650 nm with a homogeneous and smooth surface morphology. The SPME nanofibers coating was optimized for PEI percentage, electrospinning voltage, and time. The extraction efficiency of the coating was investigated for headspace SPME of some environmentally important polycyclic aromatic hydrocarbons from aqueous samples followed by... 

    Immersed solvent microextraction of aryloxyphenoxypropionate herbicides from aquatic media

    , Article International Journal of Environmental Analytical Chemistry ; Volume 93, Issue 4 , Feb , 2013 , Pages 450-460 ; 03067319 (ISSN) Bagheri, H ; Es'haghi, A ; Es-haghi, A ; Sharif University of Technology
    2013
    Abstract
    An immersed solvent microextraction (SME) method was successfully developed for the trace enrichment of aryloxyphenoxypropionate herbicides from aquatic media. A microdrop of toluene was used as the extraction solvent. Some important extraction parameters such as type of solvent, solvent dropsize, stirring rate, ionic strength and extraction time were investigated and optimized. The microdrop volume of 1.5 μL, a sampling time of 25 min, and use of toluene were major parameters for achieving high enrichment factors. The linearity was studied by preconcentration of 4 mL of the water samples spiked with a standard solution of aryloxyphenoxypropionates at the concentration range of 0.15 to 30 ng... 

    Spectrophotometric determination of glutathione and cysteine based on aggregation of colloidal gold nanoparticles

    , Article Scientia Iranica ; Volume 19, Issue 3 , June , 2012 , Pages 958-963 ; 10263098 (ISSN) Hormozi Nezhad, M. R ; Seyedhosseini, E ; Robatjazi, H ; Sharif University of Technology
    2012
    Abstract
    We report herein the development of a highly sensitive colorimetric method for the determination of cysteine and glutathione, based on aggregation of the citrate capped gold nanoparticles (Au NPs). This was exploited from high affinity of low-molecular-weight aminothiols towards the Au NPs surface, which could induce displacement of the citrate shell by the thiolate shell of target molecules, resulting in aggregation of the NPs through intermolecular electrostatic interaction or hydrogen-bonding. As a result of aggregation, which can be affected by the ionic strength, pH and concentration of Au NPs, the plasmon band at around 521 nm decreases gradually, along with formation of a new red... 

    Magnetic nanoparticle-based micro-solid phase extraction and GC-MS determination of oxadiargyl in aqueous samples

    , Article Chromatographia ; Volume 74, Issue 5-6 , 2011 , Pages 483-488 ; 00095893 (ISSN) Bagheri, H ; Zandi, O ; Aghakhani, A ; Sharif University of Technology
    Abstract
    A new facile, rapid, inexpensive, and sensitive method based on magnetic micro-solid phase extraction (M-μ-SPE) coupled to gas chromatography-mass spectrometry (GC-MS) was developed for determination of the herbicide oxadiargyl in environmental water samples. The feasibility of employing non-modified magnetic nanoparticles (MNPs) as sorbent was examined and applied to perform the extraction process. Influential parameters affecting the extraction efficiency along with desorption conditions were investigated and optimized. The limit of detection (LOD, S/N = 3) and limit of quantification (LOQ, S/N = 10) of the method under optimized conditions were 0.005 and 0.030 ng mL-1, respectively. The... 

    Thermodynamic modeling of the KCl + formamide/glucose/proline + water ternary systems and activity coefficient prediction based on artificial neural network

    , Article Journal of Molecular Liquids ; Volume 207 , 2015 , Pages 136-144 ; 01677322 (ISSN) Ghalami Choobar, B ; Ghalami Choobar, B ; Sharif University of Technology
    Elsevier  2015
    Abstract
    In this research, thermodynamic modeling and activity coefficient prediction of KCl in the (water + formamide/glucose/proline) mixed solvent systems were reported. Thermodynamic study was performed using the potentiometric data based on extended ion interaction Pitzer-Archer model in various mixed solvent systems containing 0, 10, 20, 30 and 40% mass fractions of formamide and glucose at T = 298.2 K and 0, 2.5, 5.0, 7.5 and 10.0% mass fractions of proline at T = 308.2 K and ambient pressure over ionic strength ranging from 0.0014 to 3.9579 mol·kg- 1. The adjustable parameters were determined and the obtained results were then interpreted based on extended ion interaction Pitzer-Archer model....