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Thermodynamic Properties of Aqueous Electrolyte Solutions Containing Urea
, M.Sc. Thesis Sharif University of Technology ; Ghotbi, Siroos (Supervisor) ; Taghikhani, Vahid (Supervisor)
Abstract
The behavior of biomolecules in mixtures is affected by the presence of electrolytes. For instance, in the presence of an electrolyte, solubility of most biomolecules like proteins,peptids and amino acids can be increased or decreased. As a biomolecule, urea is a protein denaturant and influences protein folding and protein-DNA binding. The presence of ions can affect the interactions between urea and water In this thesis, experimental data of density and electrical conductance of aqueous solutions of urea-NaCl were obtained at different physical conditions. Density measurement experiments were carried out at different temperatures from 20-40 oC. Apparent and infinite dilution molar volumes...
Experimental Study and Modeling of Saturation Molality of Inorganic Salts in formation water
, M.Sc. Thesis Sharif University of Technology ; Taghikhani, Vahid (Supervisor) ; Ghotbi, Sirous (Supervisor) ; Yousefi, Leyla (Co-Advisor)
Abstract
Saturation molality for a number of single and mixed aqueous electrolyte solutions containing NaCl, Na2CO3, and K2SO4, was measured at atmospheric pressure over a wide range of temperature. In order to check the repeatability of the experimental data, the experiments were replicated three times and average of the results was considered as final saturation molality. Experimental data of saturation molality for single electrolyte solutions were correlated using the modified UNIFAC–Dortmund model to account for the shortrange interaction. Binary interaction parameters, between water molecules and ionic species were also reported. For the long-range interactions between the ionic species in...
Thermodynamics and Kinetics Study of Gas Hydrates in Presence of Ionic Liquids
, M.Sc. Thesis Sharif University of Technology ; Ghotbi, Cyrus (Supervisor) ; Taghikhani, Vahid (Supervisor) ; Nazari, Khodadad (Supervisor)
Abstract
Gas hydrates are ice-like clathrate compounds. Methane, carbon dioxie and natural gas compounds can form gas hydrate and plug pipelines, in order to preventing of gas hydrate formation, inhibitors like electrolytes are added to the natural gas pipelines. In this work a model proposed to predict the hydrate formation conditions in presence of some inhibitors such as NaCl, KCl, NaBr, KBr, [BMIM][BF4] and [BMIM][Br]. So a new equation of state that can be applied to both electrolyte and associating solutions called GV-SAFT-MSA is developed. Two dialkylimidazolium ionic liquids [BMIM][BF4] and [BMIM][MS] have been investigated for their potential application as novel gas hydrate inhibitors. The...
Production of Gold with High Purity by Electrorefining Process
, M.Sc. Thesis Sharif University of Technology ; Yoozbashizadeh, Hossein (Supervisor)
Abstract
Gold is a noble and precious metal used in various industries, including jewelry, electrical and electronic, catalyst, and medical industries. Multiple processes are used to extract and refine gold; each one has its advantages and disadvantages. In this research Work, comprehensive information on the electrochemical purification process of gold from anode electrode with 75% crude gold and titanium cathode electrode in the chloride electrolyte solution is presented. To perform the purification process, first using the parameters and their levels, including temperature (30, 45, and 60 degrees Celsius), voltage (2, 2.2, and 2.4 volts), and acid concentration (1, 2, and 3 M), Design of...
Prediction of Thermodynamic Parameters in Solutions with Similar Composition to Plasma or Blood
, Ph.D. Dissertation Sharif University of Technology ; Abdekhodaie, Mohammad Jafar (Supervisor) ; Ghotbi, Cyrus (Co-Advisor)
Abstract
Serum osmolality is an important physiological quantity that is directly related to health condition of human body. Glucose, urea, and NaCl are the main components which determine the value of serum osmolality. Besides, calcium and potassium are vital inorganic cations for the body. Thus, it is of high importance to investigate the interactions between these physiological solutes in aqueous solution. Thermodynamic quantities like osmotic and activity coefficients contain enthalpic and entropic information and thus are a direct measure of interactions in these complex systems. Thus, theoretical and experimental methods were applied to investigate these thermodynamic parameters in multi-solute...
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
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...
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
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...
The role of ion partitioning in electrohydrodynamic characteristics of soft nanofluidics: Inclusion of EDL overlap and steric effects
, Article Chemical Engineering Science ; Volume 190 , 2018 , Pages 443-458 ; 00092509 (ISSN) ; Saidi, M. H ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In this paper, we aim to account for the partitioning of finite sized ions and electric double layer (EDL) overlapping effects on the electrostatics and hydrodynamics of soft nanofluidics by stablishing a modified Poisson-Boltzmann (MPB) equation enjoying mean field approach. The application of the present MPB equation enables us to describe the interaction between the steric effect and electrostatic repulsion of EDL ions due to permittivity difference of polyelectrolyte layer (PEL) and electrolyte solution. Utilizing the Debye-Hückel approximation pertinent to low surface potentials, we analytically derive the solutions of electric potential and velocity profiles of mixed electroosmotic and...
Mapping geographical inequalities in oral rehydration therapy coverage in low-income and middle-income countries, 2000-17
, Article The Lancet Global Health ; Volume 8, Issue 8 , 2020 , Pages e1038-e1060 ; Lindstedt, P. A ; Blacker, B. F ; Johnson, K. B ; Baumann, M. M ; Schaeffer, L. E ; Abbastabar, H ; Abd Allah, F ; Abdelalim, A ; Abdollahpour, I ; Abegaz, K. H ; Abejie, A. N ; Abreu, L. G ; Abrigo, M. R. M ; Abualhasan, A ; Accrombessi, M. M. K ; Acharya, D ; Adabi, M ; Adamu, A. A ; Adebayo, O. M ; Adedoyin, R. A ; Adekanmbi, V ; Adetokunboh, O. O ; Adhena, B. M ; Afarideh, M ; Ahmad, S ; Ahmadi, K ; Ahmed, A. E ; Ahmed, M. B ; Ahmed, R ; Akalu, T. Y ; Alahdab, F ; A Aly, Z ; Alam, N ; Alam, S ; Alamene, G. M ; Alanzi, T. M ; Alcalde Rabanal, J. E ; Ali, B. A ; Alijanzadeh, M ; Alipour, V ; Aljunid, S. M ; Almasi, A ; Almasi Hashiani, A ; Al Mekhlafi, H. M ; Altirkawi, K. A ; Alvis Guzman, N ; Alvis Zakzuk, N. J ; Amini, S ; Amit, A. M. L ; Andrei, C. L ; Anjomshoa, M ; Anoushiravani, A ; Ansari, F ; Antonio, C. A. T ; Antony, B ; Antriyandarti, E ; Arabloo, J ; Aref, H. M. A ; Aremu, O ; Armoon, B ; Arora, A ; Aryal, K. K ; Arzani, A ; Asadi Aliabadi, M ; Atalay, H. T ; Athari, S. S ; Athari, S. M ; Atre, S. R ; Ausloos, M ; Awoke, N ; Ayala Quintanilla, B. P ; Ayano, G ; Ayanore, M. A ; Aynalem, Y. A ; Azari, S ; Azzopardi, P. S ; Babaee, E ; Babalola, T. K ; Badawi, A ; Bairwa, M ; Bakkannavar, S. M ; Balakrishnan, S ; Bali, A. G ; Banach, M ; Banoub, J. A. M ; Barac, A ; Bärnighausen, T. W ; Basaleem, H ; Basu, S ; Bay, V. D ; Bayati, M ; Baye, E ; Bedi, N ; Beheshti, M ; Behzadifar, M ; Behzadifar, M ; Bekele, B. B ; Belayneh, Y. M ; Bell, M. L ; Bennett, D. A ; Berbada, D. A ; Bernstein, R. S ; Bhat, A. G ; Bhattacharyya, K ; Bhattarai, S ; Bhaumik, S ; Bhutta, Z. A ; Bijani, A ; Bikbov, B ; Birihane, B. M ; Biswas, R. K ; Bohlouli, S ; Bojia, H. A ; Boufous, S ; Brady, O. J ; Bragazzi, N. L ; Briko, A. N ; Briko, N. I ; Britton, G. B ; Burugina Nagaraja, S ; Busse, R ; Butt, Z. A ; Cámera, L. A ; Campos Nonato, I. R ; Cano, J ; Car, J ; Cárdenas, R ; Carvalho, F ; Castañeda Orjuela, C. A ; Castro, F ; Chanie, W. F ; Chatterjee, P ; Chattu, V. K ; Chichiabellu, T. Y ; Chin, K. L ; Christopher, D. J ; Chu, D. T ; Cormier, N. M ; Costa, V. M ; Culquichicon, C ; Daba, M. S ; Damiani, G ; Dandona, L ; Dandona, R ; Dang, A. K ; Darwesh, A. M ; Darwish, A. H ; Daryani, A ; Das, J. K ; Das Gupta, R. D ; Dash, A. P ; Davey, G ; Dávila Cervantes, C. A ; Davis, A. C ; Davitoiu, D. V ; De la Hoz, F. P ; Demis, A. B ; Demissie, D. B ; Demissie, G. D ; Demoz, G. T ; Denova Gutiérrez, E ; Deribe, K ; Desalew, A ; Deshpande, A ; Dharmaratne, S. D ; Dhillon, P ; Dhimal, M ; Dhungana, G. P ; Diaz, D ; Dipeolu, I. O ; Djalalinia, S ; Doyle, K. E ; Dubljanin, E ; Duko, B ; Duraes, A. R ; Ebrahimi Kalan, M ; Edinur, H. A ; Effiong, A ; Eftekhari, A ; El Nahas, N ; El Sayed, I ; El Sayed Zaki, M ; El Tantawi, M ; Elema, T. B ; Elhabashy, H. R ; El-Jaafary, S. I ; Elkout, H ; Elsharkawy, A ; Elyazar, I. R. F ; Endalamaw, A ; Endalew, D. A ; Eskandarieh, S ; Esteghamati, A ; Esteghamati, S ; Etemadi, A ; Ezekannagha, O ; Fareed, M ; Faridnia, R ; Farzadfar, F ; Fazlzadeh, M ; Feigin, V. L ; Fereshtehnejad, S. M ; Fernandes, E ; Filip, I ; Fischer, F ; Foigt, N. A ; Folayan, M. O ; Foroutan, M ; Franklin, R. C ; Fukumoto, T ; Gad, M. M ; Gayesa, R. T ; Gebre, T ; Gebremedhin, K. B ; Gebremeskel, G. G ; Gesesew, H. A ; Gezae, K. E ; Ghadiri, K ; Ghashghaee, A ; Ghimire, P. R ; Gill, P. S ; Gill, T. K ; Ginindza, T. G ; Gomes, N. G ; Gopalani, S. V ; Goulart, A. C ; Goulart, B. N. G ; Grada, A ; Gubari, M. I. M ; Gugnani, H. C ; Guido, D ; Guimarães, R. A ; Guo, Y ; Gupta, R ; Hafezi Nejad, N ; Haile, D. H ; Hailu, G. B ; Haj Mirzaian, A ; Haj Mirzaian, A ; Hamadeh, R. R ; Hamidi, S ; Handiso, D. W ; Haririan, H ; Hariyani, N ; Hasaballah, A. I ; Hasan, M. M ; Hasanpoor, E ; Hasanzadeh, A ; Hassankhani, H ; Hassen, H. Y ; Hegazy, M. I ; Heibati, B ; Heidari, B ; Hendrie, D ; Henry, N. J ; Herteliu, C ; Heydarpour, F ; Hidru, H. D. D ; Hird, T. R ; Hoang, C. L ; Homaie Rad, E. H ; Hoogar, P ; Hoseini, M ; Hossain, N ; Hosseini, M ; Hosseinzadeh, M ; Househ, M ; Hsairi, M ; Hu, G ; Hussen, M. M ; Ibitoye, S. E ; Igumbor, E. U ; Ilesanmi, O. S ; Ilic, M. D ; Imani Nasab, M. H ; Iqbal, U ; Irvani, S. S. N ; Islam, S. M. S ; Iwu, C. J ; Izadi, N ; Jaca, A ; Jahanmehr, N ; Jakovljevic, M ; Jalali, A ; Jayatilleke, A. U ; Jha, R. P ; Jha, V ; Ji, J. S ; Jonas, J. B ; Jozwiak, J. J ; Kabir, A ; Kabir, Z ; Kahsay, A ; Kalani, H ; Kanchan, T ; Karami Matin, B ; Karch, A ; Karim, M. A ; Karimi Sari Surendra Karki, H ; Kasaeian, A ; Kasahun, G. G ; Kasahun, Y. C ; Kasaye, H. K ; Kassa, G. G ; Kassa, G. M ; Kayode, G. A ; Kazemi Karyani, A ; Kebede, M. M ; Keiyoro, P. N ; Kelbore, A. G ; Kengne, A. P ; Ketema, D. B ; Khader, Y. S ; Khafaie, M. A ; Khalid, N ; Khalilov, R ; Khan, E. A ; Khan, J ; Khan, M. N ; Khan, M. S ; Khatab, K ; Khater, A. M ; Khater, M. M ; Khayamzadeh, M ; Khazaei, M ; Khazaei, S ; Khosravi, M. H ; Khubchandani, J ; Kiadaliri, A ; Kim, Y. J ; Kimokoti, R. W ; Kisa, A ; Kisa, S ; Kissoon, N ; Shivakumar, K. M ; Kochhar, S ; Kolola, T ; Komaki, H ; Kosen, S ; Koul, P. A ; Koyanagi, A ; Kraemer, M. U. G ; Krishan, K ; Kugbey, N ; Kumar, G. A ; Kumar, M ; Kumar, P ; Kumar, V ; Kusuma, D ; La Vecchia, C ; Lacey, B ; Lad, S. D ; Lal, D. K ; Lam, F ; Lami, F. H ; Lamichhane, P ; Lansingh, V. C ; Lasrado, S ; Laxmaiah, A ; Lee, P. H ; LeGrand, K. E ; Leili, M ; Lenjebo, T. L ; Leshargie, C. T ; Levine, A. J ; Li, S ; Linn, S ; Liu, S ; Liu, S ; Lodha, R ; Longbottom, J ; Lopez, J. C. F ; Magdy Abd El Razek, H ; Magdy Abd El Razek, M ; Mahadeshwara Prasad, DR ; Mahasha, P. W ; Mahotra, N. B ; Majeed, A ; Malekzadeh, R ; Malta, D. C ; Mamun, A. A ; Manafi, N ; Manda, A. L ; Manohar, N. D. D ; Mansournia, M. A ; Mapoma, C. C ; Maravilla, J. C ; Martinez, G ; Martini, S ; Martins-Melo, F. R ; Masaka, A ; Massenburg, B. B ; Mathur, M. R ; Mayala, B. K ; Mazidi, M ; McAlinden, C ; Meharie, B. G ; Mehndiratta, M. M ; Mehta, K. M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Background: Oral rehydration solution (ORS) is a form of oral rehydration therapy (ORT) for diarrhoea that has the potential to drastically reduce child mortality; yet, according to UNICEF estimates, less than half of children younger than 5 years with diarrhoea in low-income and middle-income countries (LMICs) received ORS in 2016. A variety of recommended home fluids (RHF) exist as alternative forms of ORT; however, it is unclear whether RHF prevent child mortality. Previous studies have shown considerable variation between countries in ORS and RHF use, but subnational variation is unknown. This study aims to produce high-resolution geospatial estimates of relative and absolute coverage of...
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
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 transient model of vanadium redox flow battery
, Article Mechanics and Industry ; Volume 17, Issue 4 , 2016 ; 22577777 (ISSN) ; Elyasi, S ; Sharif University of Technology
EDP Sciences
2016
Abstract
It has been attempted to gain a new viewpoint in transient cell modeling of vanadium redox flow battery. This has been achieved by considering electrochemical relations along with conceptual electrical circuit of this kind of battery. The redox flow battery is one of the best rechargeable batteries because of its capability to average loads and output power sources. A model of transient behavior is presented in this paper. The transient features are considered as the most remarkable characteristics of the battery. The chemical reactions, fluid flow, and electrical circuit of the structure govern the dynamics. The transient behavior of the redox flow battery based on chemical reactions is...
Potential application of silica nanoparticles for wettability alteration of oil-wet calcite: A mechanistic study
, Article Energy and Fuels ; Volume 30, Issue 5 , 2016 , Pages 3947-3961 ; 08870624 (ISSN) ; Ghazanfari, M. H ; Jamialahmadi, M ; Helalizadeh, A ; Sharif University of Technology
American Chemical Society
2016
Abstract
Oil recovery from carbonate reservoirs can be enhanced by altering the wettability from oil-wet toward water-wet state. Recently, silica nanoparticle (SNP) suspensions are considered as an attractive wettability alteration agent in enhanced oil recovery applications. However, their performance along with the underlying mechanism for wettability alteration in carbonate rocks is not well discussed. In this work, the ability of SNP suspensions, in the presence/absence of salt, to alter the wettability of oil-wet calcite substrates to a water-wet condition was investigated. In the first step, to ensure that the properties of nanofluids have not been changed during the tests, stability analysis...
Atomistic insight into the behavior of ions at an oil-bearing hydrated calcite surface: implication to ion-engineered waterflooding
, Article Energy and Fuels ; Volume 35, Issue 16 , 2021 , Pages 13039-13054 ; 08870624 (ISSN) ; Koleini, M. M ; Greenwell, H. C ; Ayatollahi, S ; Ghazanfari, M. H ; Sharif University of Technology
American Chemical Society
2021
Abstract
This research provides an atomistic picture of the role of ions in modulating the microstructural features of an oil-contaminated calcite surface. This is of crucial importance for the rational design of ion-engineered waterflooding, a promising technique for enhancing oil recovery from carbonate reservoirs. Inspired by a conventional lab-scale procedure, an integrated series of molecular dynamics (MD) simulations were carried out to resolve the relative contribution of the major ionic constituent of natural brines (i.e., Na+, Cl-, Mg2+, Ca2+, and SO42-) when soaking an oil-bearing calcite surface in different electrolyte solutions of same salinity, namely, CaCl2, MgCl2, Na2SO4, MgSO4, and...
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
Abstract
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
Prediction of the aqueous solubility of BaSO4 using pitzer ion interaction model and LSSVM algorithm
, Article Fluid Phase Equilibria ; Vol. 374, issue , July , 2014 , p. 48-62 ; ISSN: 03783812 ; Shokrollahi, A ; Jamialahmadi, M ; Ghazanfari, M. H ; Bahadori, A ; Zendehboudi, S ; Sharif University of Technology
Abstract
Deposition of barium sulfate (or BaSO4) has already been recognized as a devastating problem facing process industries and oilfield operations, mainly owing to its low solubility in aqueous solutions. Predicting and also preventing the overall damage caused by BaSO4 precipitation requires a profound knowledge of its solubility under different thermodynamic conditions. The main aim of this study is to develop a solubility prediction model based on a hybrid of least squares support vector nachines (LSSVM) and coupled simulated annealing (CSA) aiming to predict the solubility of barium sulfate over wide ranges of temperature, pressure and ionic compositions. Results indicate that predictions of...
Heat transfer characteristics of mixed electroosmotic and pressure driven flow of power-law fluids in a slit microchannel
, Article International Journal of Thermal Sciences ; Volume 53 , 2012 , Pages 71-79 ; 12900729 (ISSN) ; Saidi, M. H ; Sadeghi, A ; Sharif University of Technology
2012
Abstract
Thermal transport characteristics of electroosmotic flow of power-law fluids in the presence of pressure gradient through a slit microchannel are studied in this paper. Considering a fully developed flow with a constant wall heat flux as the boundary condition, the governing equations are numerically solved by means of the finite difference method. A complete parametric study is done in order to investigate the effects of different flow parameters on the thermal behaviors of the flow. The results show that the non-Newtonian characteristic of the fluid can influence the thermal behaviors of the flow by affecting the rate of heat convection and viscous dissipation; however, its influence...
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
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...
Experimental study and modelling of saturation molality of NaCl in quaternary aqueous electrolyte solutions at various temperatures
, Article Desalination ; Volume 267, Issue 2-3 , February , 2011 , Pages 228-232 ; 00119164 (ISSN) ; Roayaei, E ; Taghikhani, V ; Safekordi, A ; Zahedzadeh, M ; Sharif University of Technology
2011
Abstract
Saturation molality of sodium chloride in mixed aqueous electrolyte solutions containing NaCl, CaSO4 and Na2SO4 was measured at atmospheric pressure over the wide range of temperatures using an equilibrium cell equipped with an accurate temperature control system. The measurements were carried out at different CaSO4 and Na2SO4 concentrations. In order to check the repeatability of the experimental data for the saturation molality of NaCl, the experiments were replicated three times and the values reported were the average of the replicas. To model the data generated in this work, the PDH+UNIFAC-Dortmund activity coefficient model was used. The model used to predict the mean ionic activity...
Self-organized titanium oxide nanotubes prepared in phosphate electrolytes: Effect of voltage and fluorine concentration
, Article ECS Transactions, 25 April 2010 through 30 April 2010 ; Volume 28, Issue 7 , April , 2010 , Pages 67-74 ; 19385862 (ISSN) ; 9781607681830 (ISBN) ; Dolati, A ; Goodarzi, M ; Askari, M ; Ghahramaninezhad, A ; ECS All Divisions ; Sharif University of Technology
2010
Abstract
TiO2 a nanotube array was prepared using an anodization process. The process proceeded in a two-electrode cell containing of platinum sheet as the cathode electrode. Two phosphate-base electrolyte solutions containing different amounts of HF and NH4F were prepared. Different concentration of fluorine ions were examined in respected electrolytes. Current transient techniques were used to produce the TiO2 nanotubes at constant voltage of 18-25V. It was revealed that anodization at 18-22V, in so-called electrolytes would end up to nano-tubular structure. However the tubular structure prepared at 20V and from phosphate electrolyte containing of 0.5 wt% NH4F as well as 0.5 wt% HF, was recognized...
Measurement and correlation of surface tension for single aqueous electrolyte solutions
, Article International Journal of Thermophysics ; Volume 31, Issue 4-5 , May , 2010 , Pages 852-859 ; 0195928X (ISSN) ; Taghikhani, V ; Ghotbi, C ; Sharif University of Technology
2010
Abstract
In this study, the values of the surface tension for a number of single aqueous electrolyte solutions were measured at various temperatures and electrolyte concentrations using the well-known and computer-aided pendant-drop method. In order to conduct the experimental measurements, a high-pressure IFT-700 apparatus, equipped with a view cell and a data acquisition system, was used. The systems studied in this study were aqueous solutions of KCl, NaCl, CaCl 2, and Na 2SO 4. The pooled standard deviation and the confidence limit of the surface-tension data for a 95 % confidence level were determined to be 0.17mN · m -1 and σ̄ ± 0.19, respectively. It should be noted that while the surface...