Search for: electrolytes
Total 296 records
On the correlation of the activity coefficients in aqueous electrolyte solutions using the K-MSA model, Article Industrial and Engineering Chemistry Research ; Volume 42, Issue 6 , 2003 , Pages 1279-1284 ; 08885885 (ISSN) ; Azimi, G ; Taghikhani, V ; Vera, J.H ; Sharif University of Technology
American Chemical Society 2003
The objective of this work is to extend the Kelvin mean spherical approximation (K-MSA) model to correlate the mean and individual ionic activity coefficients for symmetric and asymmetric electrolyte solutions at different concentrations and at different temperatures. Revised values of the parameters for the mean and individual ionic activity coefficients of 1:1 electrolytes and new values of the parameters for the mean ionic activity coefficients of asymmetric electrolytes are presented. The effect of the short-range electrostatic term (Pn) at different size ratios of the ions is examined. Assuming a constant anion diameter and a composition-dependent diameter for the cation, the K-MSA...
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) ; Sharifian, M ; Sharif University of Technology
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) ; Patel, B. H ; Galindo, A ; Ghotbi, C ; Sharif University of Technology
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) ; Taghikhani, V ; Vossoughi, M ; Sharif University of Technology
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...
Interaction effects in multicomponent separation by reverse osmosis, Article Journal of Membrane Science ; Volume 183, Issue 1 , 2001 , Pages 15-27 ; 03767388 (ISSN) ; Sahebdelfar, S ; Sharif University of Technology
Separation of multicomponent mixtures, in particular ternary systems, was investigated theoretically and experimentally. The interactions in various multicomponent mixtures were determined. Using data from literature as well as the limited data obtained in our laboratory, we identified the situations where the multicomponent effects are strong. A correlation between the coupled permeability coefficients and straight permeability coefficients and concentration of components in ternary systems was obtained. Capabilities of thermodynamic models in describing the electrolyte-nonelectrolyte systems consisting of a weak acid were also investigated. The results of this work show that the...
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) ; Iraji zad, A ; Mohammadpour, R ; Sharif University of Technology
Elsevier Inc 2018
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) ; Taghikhani, V ; Ghotbi, C ; Sharif University of Technology
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) ; Ghotbi, C ; Taghikhani, V ; Sharif University of Technology
Sharif University of Technology 2005
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) ; Ghotbi, C ; Abdekhodaie, M. J ; Sharif University of Technology
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) ; Tajabadi, F ; Jabbari, A ; Taghavinia, N ; Sharif University of Technology
Springer Verlag 2015
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) ; Pazuki, G. R ; Taghikhani, V ; Vossoughi, M ; Ghotbi, C ; Sharif University of Technology
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) ; Taghikhani, V ; Vossoughi, M ; Sharif University of Technology
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 ; Rowshanzamir, S ; Eikani, M. H ; Sedghid, S ; Peighambardoust, S. J ; Sharif University of Technology
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) ; Rashtchian, D ; Ghotbi, C ; Taghikhani, V ; Khayat, G ; Sharif University of Technology
Iranian Journal of Chemistry and Chemical Engineering 2007
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) ; Asgari, M ; Daneshmand, H ; Karimi, M ; Sabour Rouhaghdam, A ; Sharif University of Technology
Elsevier B.V 2021
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...
The MSA and the individual ionic activity coefficients, Article Iranian Journal of Science and Technology, Transaction B: Technology ; Volume 27, Issue 2 , 2003 , Pages 247-252 ; 03601307 (ISSN) ; Modarress, H ; Khoshkbarchi, M. K ; Vera, J. H ; Sharif University of Technology
The mean spherical approximation (MSA) has been applied to accurately correlate the activity coefficients of individual ions in aqueòus solutions of single 1:1 electrolytes. In order to account for changes in the hydration of the ions, the size parameters of the ions are considered to be composition dependent. The values of the size parameters show that the hydration of the ions decreases as the electrolyte concentration increases. Results obtained from the full MSA and from a simplified version of MSA (SMSA), were compared. The use of the simplified version had a small effect on the final results and dramatically reduced the computation of the effort
Correlation of the mean ionic activity coefficients in 1:1 electrolyte solutions using the GV-MSA model, Article Iranian Journal of Science and Technology, Transaction B: Technology ; Volume 27, Issue 2 , 2003 , Pages 269-278 ; 03601307 (ISSN) ; Taghikhani, V ; Azimi, G ; Sharif University of Technology
The Ghotbi-Vera hard sphere equation of state as the reference system, coupled with the mean spherical approximation, (GV-MSA), has been used to accurately correlate the mean ionic activity coefficients of aqueous solutions of single 1:1 electrolytes. The new equation of state considers the ions to be hard spheres in Kelvin tetrakaidekahedron cells. The mean ionic activity coefficients of the electrolytes can be correlated with constant diameter of anions, equal to the crystallographic Pauling diameter and with a concentration dependent relation for the cations. In comparison to their crystallographic Pauling diameters, the new model for the mean ionic activity coefficient produces realistic...
Measurement of activity coefficients of amino acids in aqueous electrolyte solutions: Experimental data for the systems (H2O + NaBr + glycine) and (H2O + NaBr + L-valine) at T = 298.15 K, Article Journal of Chemical Thermodynamics ; Volume 35, Issue 9 , 2003 , Pages 1553-1565 ; 00219614 (ISSN) ; Modarress, H ; Taghikhani, V ; Khoshkbarchi, M. K ; Sharif University of Technology
Academic Press 2003
Electrochemical cells with two ion-selective electrodes, a cation ion-selective electrode against an anion ion-selective electrode, were used to measure the activity coefficient of amino acids in aqueous electrolyte solutions. Activity coefficient data were measured for (H2O + NaBr + glycine) and (H2O + NaBr + L-valine) at T = 298.15 K. The maximum concentrations of sodium bromide, glycine, and L-valine were (1.0, 2.4, and 0.4) mol · kg-1, respectively. The results show that the presence of an electrolyte and the nature of both the cation and the anion of the electrolyte have significant effects on the activity coefficients of amino acid in aqueous electrolyte solutions
Activity coefficients of electrolyte and amino acid in the systems (water + potassium chloride + DL-valine) at T = 298.15 K and (water + sodium chloride + L-valine) at T = 308.15 K, Article Journal of Chemical Thermodynamics ; Volume 34, Issue 8 , 2002 , Pages 1297-1309 ; 00219614 (ISSN) ; Modarress, H ; Taghikhani, V ; Khoshkbarchi, M. K ; Sharif University of Technology
The activity coefficient data were reported for (water + potassium chloride + DL-valine) at T = 298.15 K and (water + sodium chloride + L-valine) at T = 308.15 K. The measurements were performed in an electrochemical cell using ion-selective electrodes. The maximum concentrations of the electrolytes and the amino acids studied were 1.0 molality and 0.4 molality, respectively. The results of the activity coefficients of DL-valine are compared with the activity coefficients of DL-valine in (water + sodium chloride + DL-valine) system obtained from the previous study. The results show that the presence of an electrolyte and the nature of its cation have a significant effect on the activity...
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) ; Taghikhani, V ; Vossoughi, M ; Sharif University of Technology
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...