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    Study of electrical conductivity of different water liquids and electrolytes

    , Article Australian Journal of Basic and Applied Sciences ; Volume 4, Issue 8 , 2010 , Pages 3985-3997 ; 19918178 (ISSN) Golnabi, H ; Sharifian, M ; Sharif University of Technology
    2010
    Abstract
    In this study electrical conductivities of pure, distilled, municipal, industrial and river water liquids along with those of different electrolyte solutions are computed at room temperature (25 °C) and compared with the experimental results. For experiment, using a measuring module both R and C value of the water samples are measured by using two different cylindrical cells. The obtained RC product for the long and short cell probes are compared for different water samples. Obtained results give the relaxation time, which is the measure of the conduction relaxation and for a good conducting medium such a time is very short. The relaxation time for the salt solution is about 0.07044 ms... 

    Modeling electrolyte solutions with the SAFT-VR equation using Yukawa potentials and the mean-spherical approximation

    , Article Fluid Phase Equilibria ; Volume 236, Issue 1-2 , 2005 , Pages 241-255 ; 03783812 (ISSN) Behzadi, B ; Patel, B. H ; Galindo, A ; Ghotbi, C ; Sharif University of Technology
    Elsevier  2005
    Abstract
    An equation of state based on the statistical associating fluid theory for potentials of variable range (SAFT-VR) is used to model 7 hydrogen-bonding solvents and 23 electrolyte solutions. Solvent-solvent hydrogen bonding interactions are explicitly taken into account as in other versions of the SAFT approach. In addition, long-range Coulombic interactions between ionic species are accounted for using the non-restricted mean-spherical approximation, while solvent-solvent and solvent-ion dispersion interactions are included and are treated using Yukawa potentials. Previously a similar approach had been proposed in which the dispersion interactions were treated using square-well potentials. In... 

    A new hydration model in correlating the mean ionic activity coefficient and density of aqueous electrolyte solutions

    , Article Journal of Dispersion Science and Technology ; Volume 31, Issue 5 , 2010 , Pages 641-649 ; 01932691 (ISSN) Pazuki, G. R ; Taghikhani, V ; Vossoughi, M ; Sharif University of Technology
    Abstract
    In this article, a new hydration model has been proposed to study the phase behavior of aqueous electrolyte solutions. The proposed model distinguishes between an anion and cation in the electrolyte solution. The model has three adjustable parameters which can be obtained using the experimental data of the mean ionic activity coefficients for 113 electrolyte solutions. The results of the proposed model were compared with those of obtained from the Pitzer, the E-NRTL and the E-Wilson models. The results showed that the proposed model can accurately correlate the mean ionic activity coefficients of the aqueous electrolyte solutions than the other models. Also, the proposed model was used in... 

    Reproducible electrochemical analysis of nanostructured Cu2O using a non-aqueous 3-methoxypropionitrile-based electrolyte

    , Article Electrochemistry Communications ; Volume 86 , 2018 , Pages 1-5 ; 13882481 (ISSN) Shooshtari, L ; Iraji zad, A ; Mohammadpour, R ; Sharif University of Technology
    Elsevier Inc  2018
    Abstract
    Cu2O is an attractive material in terms of semiconducting properties and is considered a leading candidate in all-oxide photovoltaics. Electrochemical analysis of Cu2O, including Mott-Schottky (MS) and impedance spectroscopy (IS), provides a wealth of data on charge carriers, Fermi level and interface properties. MS and IS are usually measured in aqueous solutions. However, Cu2O is easily reduced or oxidized to Cu or CuO in aqueous solutions, the layer peels off after the analysis and there is a small voltage window for the tests. In some cases, an anti-corrosive n-type barrier layer is employed on top of the bare Cu2O electrode to make the measurement possible, which could result in... 

    Application of the GV-MSA model to the electrolyte solutions containing mixed salts and mixed solvents

    , Article Fluid Phase Equilibria ; Volume 231, Issue 1 , 2005 , Pages 67-76 ; 03783812 (ISSN) Salimi, H. R ; Taghikhani, V ; Ghotbi, C ; Sharif University of Technology
    2005
    Abstract
    In this work the Ghotbi-Vera mean spherical approximation (GV-MSA) model, coupled with two different expressions for the cation-hydrated diameters, was used in predicting the mean ionic activity coefficients (MIAC) of electrolytes for a number of the mixed-solvent and mixed-salt electrolyte solutions at 25 °C. In all cases the cation diameters in solutions changed with concentration of electrolyte while the anion diameters were considered to be constant and equal to the corresponding Pauling diameters. In application of the GV-MSA model to the electrolyte systems, two different expressions were used for concentration dependency of cation-hydrated diameters, i.e., the GV-MSA1 and GV-MSA2... 

    Application of the Pitzer and the MSA-based models in predicting the activity and the osmotic coefficients of aqueous electrolyte solutions

    , Article Scientia Iranica ; Volume 12, Issue 3 , 2005 , Pages 280-289 ; 10263098 (ISSN) Azimi, G ; Ghotbi, C ; Taghikhani, V ; Sharif University of Technology
    Sharif University of Technology  2005
    Abstract
    The GV-MSA, the BMCSL-MSA and the Pitzer models were used to correlate the individual, the mean ionic activity coefficients and the osmotic coefficients of symmetric and asymmetric electrolyte solutions. In order to compare the results obtained from the GV-MSA with those obtained from the Pitzer and the BMCSL-MSA models, the same experimental data and the same minimization procedure were used and the new sets of parameters for the BMCSL-MSA and the Pitzer models were also reported. The values for the osmotic coefficients of electrolyte solutions were calculated directly using the values of the mean ionic activity coefficients obtained from the models studied in this work. The results for the... 

    Activity coefficient prediction for binary and ternary aqueous electrolyte solutions at different temperatures and concentrations

    , Article Journal of Solution Chemistry ; Volume 41, Issue 1 , 2012 , Pages 75-88 ; 00959782 (ISSN) Sadeghi, M ; Ghotbi, C ; Abdekhodaie, M. J ; Sharif University of Technology
    Abstract
    The mean spherical approximation (MSA) model, coupled with two hard sphere models, was used to predict the activity coefficients of mixtures of electrolyte solutions at different temperatures and concentrations. The models, namely the Ghotbi-Vera-MSA (GV-MSA) and Mansoori et al.-MSA (BMCSL-MSA), were directly used without introducing any new adjustable parameters for mixing of electrolyte solutions. In the correlation step, the anion diameters were considered to be constant, whereas the cation diameters were considered to be concentration dependent. The adjustable parameters were determined by fitting the models to the experimental mean ionic activity coefficients for single aqueous... 

    Stable dye-sensitized solar cells based on a gel electrolyte with ethyl cellulose as the gelator

    , Article Applied Physics A: Materials Science and Processing ; Volume 120, Issue 3 , September , 2015 , Pages 869-874 ; 09478396 (ISSN) Vasei, M ; Tajabadi, F ; Jabbari, A ; Taghavinia, N ; Sharif University of Technology
    Springer Verlag  2015
    Abstract
    A simple gelating process is developed for the conventional acetonitrile-based electrolyte of dye solar cells, based on ethyl cellulose as the gelator. The electrolyte becomes quasi-solid-state upon addition of an ethanolic solution of ethyl cellulose to the conventional acetonitrile-based liquid electrolyte. The photovoltaic conversion efficiency with the new gel electrolyte is only slightly lower than with the liquid electrolyte, e.g., 6.5 % for liquid electrolyte versus 5.9 % for gel electrolyte with 5.8 wt% added ethyl cellulose. Electrolyte gelation has small effect on the ionic diffusion coefficient of iodide, and the devices are remarkably stable for at least 550 h under irradiation... 

    A new gibbs energy model for obtaining thermophysical properties of aqueous electrolyte solutions

    , Article Journal of Solution Chemistry ; Volume 38, Issue 2 , 2009 , Pages 171-186 ; 00959782 (ISSN) Khederlou, K ; Pazuki, G. R ; Taghikhani, V ; Vossoughi, M ; Ghotbi, C ; Sharif University of Technology
    2009
    Abstract
    In this paper, a new Gibbs energy model is proposed to study the thermophysical properties of aqueous electrolyte solutions at various temperatures. The proposed model assumes that the electrolytes completely dissociate in solution. The model also has two temperature-independent adjustable parameters that were regressed using experimental values of the mean ionic activity coefficients (MIAC) for 87 electrolyte solutions at 298.15 K. Results from the proposed model for the MIAC were compared with those obtained from the E-Wilson, E-NRTL, Pitzer and the E-UNIQUAC models, and the adjustable model parameters were used directly to predict the osmotic coefficients at this temperature. The results... 

    A modified local composition-based model for correlating the vapor-liquid and liquid-liquid phase equilibria of aqueous polymer-salt systems

    , Article Journal of Solution Chemistry ; Volume 37, Issue 5 , 2008 , Pages 665-675 ; 00959782 (ISSN) Pazuki, G. R ; Taghikhani, V ; Vossoughi, M ; Sharif University of Technology
    2008
    Abstract
    In this research, a new local composition model has been proposed to study the vapor-liquid and liquid-liquid phase equilibria of polyelectrolyte solutions. The proposed model has been used in order to obtain the activity of water in polyethylene glycol (PEG) and polypropylene glycol (PPG) solutions. The interaction parameters introduced into the proposed model have been reported. The interaction parameters between the salt and water molecule have been estimated using the experimental mean ionic activity coefficients of aqueous electrolytes studied in this work. Also, the interaction parameters between the polymer and salt molecule, and the polymer and water molecule have been computed using... 

    High temperature proton exchange membrane fuel cells: Advantages and technical challenges

    , Article 18th International Congress of Chemical and Process Engineering, CHISA 2008, Prague, 24 August 2008 through 28 August 2008 ; 2008 Amjadi, M ; Rowshanzamir, S ; Eikani, M. H ; Sedghid, S ; Peighambardoust, S. J ; Sharif University of Technology
    2008
    Abstract
    High temperature proton exchange membrane fuel cells (HT-PEMFC) are polymeric fuel cells that can operate at 120°-200°C). Preparation of new heat-resistant HT-PEMFC materials, e.g., membrane and electrodes, is the most challenging problem for these kinds of fuel cells. A discussion covers the benefits of HT-PEMFC; challenges in developing novel materials for membranes preparation; polymeric membranes of HT-PEMFC; improvement of high temperature membranes; high temperature membranes characteristics and types; and importance of electrodes porosity for HT-PEMFC. This is an abstract of a paper presented at the 18th International Congress of Chemical and Process Engineering (Prague, Czech... 

    Prediction of hydrate formation for the systems containing single and mixed electrolyte solutions

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 26, Issue 1 , 2007 , Pages 35-45 ; 10219986 (ISSN) Shabani, M. M ; Rashtchian, D ; Ghotbi, C ; Taghikhani, V ; Khayat, G ; Sharif University of Technology
    Iranian Journal of Chemistry and Chemical Engineering  2007
    Abstract
    In this work the effect of electrolytes on hydrate formation was investigated. To do so, a new model was used in predicting the hydrate formation conditions in presence of both single and mixed electrolyte solutions. The new model is based on the van der Waals - Platteeuw hydrate equation of state. In order to evaluate the values for the activity of water in electrolyte solutions the simplified version of the Ghotbi-Vera Mean Spherical Approximation (SGV-MSA) model was used. According to the SGV-MSA model the ions in the solutions are considered as charged hard spheres with different sizes. The values of the parameters for the SGV-MSA model are independent of temperature and depend only on... 

    Effect of anode position on the incorporation of nano/microparticles during the PEO coating on AZ31B

    , Article Applied Surface Science Advances ; 2021 , Volume 6 ; 26665239 (ISSN) Esmaeili, M ; Asgari, M ; Daneshmand, H ; Karimi, M ; Sabour Rouhaghdam, A ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    In this study, the influence of the sample position (anode) on the incorporation of nano/micro alumina particles on the AZ31B magnesium alloy substrate was investigated by plasma electrolytic oxidation (PEO) coating. For characterized this effect, Scanning electron microscopy (SEM), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and pin-on-disk test were used to the evolution of the microstructure, corrosion resistance, and the wear behavior of the films. Based on the obtained results, the effect of the anode position from vertical to horizontal is dependent on particle size and it can be influenced only on the incorporation of nanoparticles. The... 

    Correlation and prediction the activity coefficients and solubility of amino acids and simple peptide in aqueous solution using the modified local composition model

    , Article Fluid Phase Equilibria ; Volume 255, Issue 2 , 2007 , Pages 160-166 ; 03783812 (ISSN) Pazuki, G. R ; Taghikhani, V ; Vossoughi, M ; Sharif University of Technology
    2007
    Abstract
    In this work, the modified Wilson model was used to obtain the activity coefficients of amino acids and simple peptides in non-electrolyte aqueous solutions. The Wilson model was modified using the new local mole fraction proposed by Zhao et al. and non-random case for the reference state. The binary interaction parameters (BIP) of the modified Wilson model for amino acid-water pairs were obtained using the experimental data of the activity coefficients for amino acids available in the literature. The modified Wilson model was also used to correlate the solubility of amino acids in water and the values of Δh/R, Δs/R, and Δg/R of the solutions studied were reported. The results obtained... 

    Improved electrochemical performance of plasma electrolytic oxidation coating on titanium in simulated body fluid

    , Article Journal of Materials Engineering and Performance ; Volume 28, Issue 7 , 2019 , Pages 4120-4127 ; 10599495 (ISSN) Ahmadnia, S ; Aliasghari, S ; Ghorbani, M ; Sharif University of Technology
    Springer New York LLC  2019
    Abstract
    The effect of plasma electrolytic oxidation (PEO) pre-treatments on corrosion behavior of titanium in simulated body fluid (SBF) is investigated. Three pre-treatments are compared, using silicate, calcium phosphate and mixed silicate and calcium phosphate (1:1) electrolytes, respectively. The resultant coatings in different compositions and morphologies were examined by high-resolution field emission scanning electron microscopy equipped with energy-dispersive spectrometer and x-ray diffraction. The PEO-treated specimens revealed distribution of coating species, mainly the titanium-rich inner coating region. However, findings show highly localized variations in composition within their... 

    Application of the MSA-based models in correlating the surface tension for single and mixed electrolyte solutions

    , Article Journal of Chemical Thermodynamics ; Volume 41, Issue 11 , 2009 , Pages 1264-1271 ; 00219614 (ISSN) Sadeghi, M ; Taghikhani, V ; Ghotbi, C ; Sharif University of Technology
    2009
    Abstract
    Experimental values for surface tension of single and mixed electrolyte solutions were correlated using the models based on the perturbation theory. The Mean Spherical Approximation (MSA) model, coupled with the Ghotbi-Vera (GV) and the Mansoori et al. (BMCSL) equations of state, were used to correlate the experimental values of the surface tension. The results showed that the models can favourably correlate the experimental values for single electrolyte solutions. However, it was observed that the GV-MSA model can more accurately predict the surface tension for single electrolytes, especially at higher concentrations. Two different expressions for concentration dependency of cation hydrated... 

    A new model in correlating the activity coefficients of aqueous electrolyte solutions with ion pair formation

    , Article Fluid Phase Equilibria ; Volume 261, Issue 1-2 , December , 2007 , Pages 313-319 ; 03783812 (ISSN) Mortazavi Manesh, S ; Taghikhani, V ; Ghotbi, C ; Sharif University of Technology
    2007
    Abstract
    In this work, the Ion Pair Modified Ghotbi-Vera Mean Spherical Approximation (IP-MGV-MSA) model was proposed to correlate the mean ionic activity coefficients (MIAC) for a number of symmetric and asymmetric aqueous electrolyte solutions at 25 °C. The new model is based on the recently proposed MGV-MSA model by Mortazavi-Manesh et al. In the IP-MGV-MSA model, the effects arising from the ion pair formation in the electrolyte solution was taken into account. Also, in the proposed model, while the cation diameter as well as the relative permittivity of water was considered to be dependent on electrolyte concentration, the anion diameter was independent of electrolyte concentration. The results... 

    plasma Electrolytic Oxidation of AZ31 in Silicate and Phosphate Electrolyte and Study of Corrosion Behavior

    , M.Sc. Thesis Sharif University of Technology Sharifi, Hassan (Author) ; Ghorbani, Mohammad (Supervisor)
    Abstract
    In recent years, magnesium and its alloys have been considered as biodegradable implants, but they corrode in the body before natural process of damaged organs recovery is completed. In this investigation PEO operation was used for corrosion control and effect of different parameter such as number of operation steps, electrolyte type, time and operation voltage on coating properties was studied. Scanning electron microscopy was used for investigating of morphology of coats and to determine chemical composition and phase of coats EDS analysis and X-ray diffraction were used. The corrosion resistance of samples were evaluated by potentiodynamic polarization and electrochemical impedance (EIS)... 

    Formation of Two-Step Plasma Electrolytic Oxidation Coating On Commercially Pure Titanium and Study its Properties

    , M.Sc. Thesis Sharif University of Technology Ahmadnia, Samira (Author) ; Ghorbani, Mohammad (Supervisor)
    Abstract
    Improvement of biological properties by modifying the composition and morphology of the surface layer is one of the main goals of using plasma electrolytic oxidation (PEO) for coating titanium implants. The purpose of this research is formation of biocompatible coating containing calcium, phosphorus and silicon on titanium by two-step PEO method in DC, constant voltage mode. In addition to good corrosion properties of the resultant coatings in simulated body environment (SBF), Having good adhesion due to the use of electrolytes with useful elements for biological function in both step of coating process rather than acidic electrolytes which are incompatible with the body environment, this... 

    Water electrolyte transport through corrugated carbon nanopores [electronic resource]

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 90, Issue 1, July 2014, Article number 012304 Moghimi Kheirabadi . A ; Moosavi. A
    Abstract
    We investigate the effect of wall roughness on water electrolyte transport characteristics at different temperatures through carbon nanotubes by using nonequilibrium molecular dynamics simulations. Our results reveal that shearing stress and the nominal viscosity increase with ion concentration in corrugated carbon nanotubes (CNTs), in contrast to cases in smooth CNTs. Also, the temperature increase leads to the reduction of shearing stress and the nominal viscosity at moderate degrees of wall roughness. At high degrees of wall roughness, the temperature increase will enhance radial movements and increases resistance against fluid motion. As the fluid velocity increases, the particles do not...