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    Stagewise modeling of liquid-liquid extraction column (RDC)

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 17, Issue 1 , 2004 , Pages 7-17 ; 1728-144X (ISSN) Bastani, D ; Sharif University of Technology
    National Research Center of Medical Sciences  2004
    Stagewise forward mixing model considering coalescence and redispersion of drops was used to predict the performance of Rotating Disc Liquid-Liquid Extraction Contactors. Experimental data previously obtained in two RDC columns of 7.62 cm diameter, 73.6cm height and 21.9cm diameter, 150cm height were used to evaluate the model predictions. Drop-side mass transfer coefficients were predicted applying Handlos-Baron drop model and Olney's model was used to predict drop velocities. According to the results obtained the followings could be concluded: (1) If the height of coalescence and redispersion i.e.: h = h pφp /φ could be estimated, the stagewise forward mixing with coalescence and... 

    Effects of liquid second viscosity in high-amplitude sonoluminescence

    , Article Chinese Physics Letters ; Volume 21, Issue 2 , 2004 , Pages 356-359 ; 0256307X (ISSN) Moshaii, A ; Sadighi Bonabi, R ; Taeibi Rahni, M ; Daemi, M ; Sharif University of Technology
    Allerton Press Inc  2004
    The well-known Rayleigh-Plesset (RP) equation is the base of nearly all hydrodynamical descriptions of the sonoluminescence phenomenon. A major deficiency of this equation is that it accounts for viscosity of an incompressible liquid and compressibility, separately. By removing this approximation, we have modified the RP equation, considering effects of liquid second viscosity. This modification exhibits its importance at the end of an intense collapse, so that the new model predicts the appearance of a new picosecond bouncing during high-amplitude sonoluminescence radiation. This new bouncing produces very sharp (sub-picosecond) peaks on the top of the sonoluminescence pulse. These new... 

    An exact treatment of ellipsoid-substrate interactions

    , Article EPL ; Volume 77, Issue 2 , 2007 ; 02955075 (ISSN) Babadi, M ; Ejtehadi, M. R ; Sharif University of Technology
    We present an exact treatment of the pairwise surface interactions of biaxial ellipsoidal bodies and derive the exact explicit expressions for the attractive-repulsive Lennard-Jones(6-12) ellipsoid-substrate interactions. The applicability of the results at nanoscale as a coarse-grained description of molecule-substrate interactions has been studied through presenting parameterizations for a number of small biaxial molecules. The study concludes that the anisotropic coarse-grained potential reproduces the atomistic interactions of ellipsoid-like rigid molecules perfectly, with a negligible error of less than 3%. Copyright © EPLA, 2007  

    Pressure-driven liquid-liquid separation in Y-shaped microfluidic junctions

    , Article Chemical Engineering Journal ; Volume 328 , 2017 , Pages 1075-1086 ; 13858947 (ISSN) Foroozan Jahromi, P ; Karimi Sabet, J ; Amini, Y ; Fadaei, H ; Sharif University of Technology
    On-chip phase separation of multiphase microflows at the divergence point of Y-shaped microfluidic junctions is an effective way for integrating continuous microstructured devices. In this study, flow pattern maps of various solvent pairs based on the volumetric flow rates of both phases have been drawn experimentally and compared with numerical prediction to investigate the effective domain for which complete phase separation occurred. Furthermore, sufficient separation of aqueous and organic phases at the end of the microchannel was achieved by controlling the pressure difference at the liquid-liquid interface via loading back-pressure on the organic phase. A mathematical model based on... 

    Impacts of SiO2 and MgO nanoparticles on mass transfer performance of batch liquid-liquid extraction

    , Article Inorganic and Nano-Metal Chemistry ; Volume 47, Issue 5 , 2017 , Pages 677-680 ; 24701556 (ISSN) Sepehri Sadeghian, S. S ; Abooali, D ; Rahbar Kelishami, A ; Sharif University of Technology
    Due to substantial impacts of nanoparticles on mass and heat transfer, having knowledge about different types of nanoparticles can contribute to access high efficiencies. As an investigation, in the present study, a number of liquid-liquid extraction experiments were designed by the use of Taguchi design model in order to study the impacts of SiO2 and MgO nanoparticles on mass transfer, in the batch systems. Acetic acid was considered as solute in some organic phases (i.e., n-butanol, n-butyl acetate, toluene, and chloroform), and pure water was applied as solvent. Taguchi experiment design method made more precision and convenience in the work. Final results showed reduction of mass... 

    Estimation of mass transfer during drop formation: New flow expansion model

    , Article 2004 ASME International Mechanical Engineering Congress and Exposition, IMECE, Anaheim, CA, 13 November 2004 through 19 November 2004 ; 2004 , Pages 27-34 ; 0791847179 (ISBN); 9780791847176 (ISBN) Javadi, A ; Bastani, D ; Sharif University of Technology
    American Society of Mechanical Engineers  2004
    Although there is extensive experimental, theoretical and numerical research on dynamics of drop formation in liquid-liquid systems, the evaluation of mass transfer during drop formation is rather complex and there has been little research on that. The various mathematical models developed for this problem are generally based on a solution of the diffusion equation without any allowance for circulation within the drop. This is the main reason for the poor prediction of these models in many cases for which internal convection has an important effect on mass transfer rate. In this paper an attempt was made to define a parameter related to the extent of the convective mixing within the growing... 

    Comparison of prism-based optical probes for liquid monitoring

    , Article Modern Physics Letters B ; Volume 24, Issue 11 , May , 2010 , Pages 1111-1126 ; 02179849 (ISSN) Golnabi, H ; Razani, M ; Sharif University of Technology
    In this article, two possible applications of prism-based probes for liquid-switching, level-sensing, and as a refractometer are described. Theoretical formulation is developed for the emergent intensity for each system and possible range of operation for each system is reported. By comparing the theoretical investigations, some hints are given in optimum usage of prism in each case. Variation of the beam divergence, incident angle, and prism glass index are major parameters that are considered in this investigation. The obtained results are compared with some available experimental results and practical points concerning the effective application of each geometry is reported. Theoretical... 

    Investigation of a two impinging-jets contacting device for liquid-liquid extraction processes

    , Article Chemical Engineering Journal ; Volume 118, Issue 3 , 2006 , Pages 3942-3950 ; 13858947 (ISSN) Saien, J ; Ebrahimzadeh Zonouzian, S. A ; Dehkordi, A. M ; Sharif University of Technology
    Elsevier  2006

    A free-volume modification of GEM-QC to correlate VLE and LLE in polymer solutions

    , Article Journal of Chemical Thermodynamics ; Volume 36, Issue 5 , 2004 , Pages 409-417 ; 00219614 (ISSN) Radfarnia, H. R ; Taghikhani, V ; Ghotbi, C ; Khoshkbarchi, M. K ; Sharif University of Technology
    Academic Press  2004
    The generalized quasi-chemical (GEM-QC) model proposed by Wang and Vera is modified to correlate better the phase equilibrium and to overcome the shortcoming of the original model to predict the lower critical solution temperature (LCST) of binary polymer solutions. This shortcoming is mainly because the GEM-QC model does not consider the effect of free-volume, which is important in systems containing molecules with large size differences. The proposed modification is based on replacing the combinatorial term of the GEM-QC model by a term proposed by Kontogerogis et al., which includes the effect of the free-volume. The main advantage of the free volume generalized quasi-chemical (GEM-QC-FV)... 

    Experimental investigation and thermodynamic modeling of amino acids partitioning in a water/ionic liquid system

    , Article Journal of Molecular Liquids ; Volume 260 , 15 June , 2018 , Pages 386-390 ; 01677322 (ISSN) Nazem, H ; Ghotbi, C ; Habibi Zare, M ; Shirazian, S ; Sharif University of Technology
    Elsevier B.V  2018
    Amino acids partitioning including phenylalanine, glutamic acid, and tryptophan in aqueous and ionic liquid phases at temperature of 298.15 K and atmospheric pressure were measured. 1-Butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide used in this work can produce two phases with water immediately. The effect of aqueous solution pH on amino acids partitioning was studied and revealed that amino acid partitioning coefficient was decreased with increasing pH. This phenomenon pertains to the electrostatic interaction between cations of amino acid and the anions of ionic liquid which is decreased when pH increases. Considering the effect of pH, liquid-liquid equilibrium data of amino... 

    A horizontally oriented setup for liquid-liquid-liquid microextraction of estrogens

    , Article Analytical Methods ; Volume 5, Issue 22 , 2013 , Pages 6517-6522 ; 17599660 (ISSN) Bagheri, H ; Maleki, H ; Es'Haghi, A ; Sharif University of Technology
    A horizontally oriented liquid-liquid-liquid microextraction (HOLLLME) setup was developed and applied for the isolation of two major estrogens from aquatic media. In contrast to the conventional procedure, in this setup the extracting microdrop was suspended from a horizontally positioned needle in order to provide much higher stability to the extracting phase. The developed HOLLLME approach was applied to isolate two major selected estrogens from aquatic media followed by high performance liquid chromatography-ultraviolet (HPLC-UV) determination. Estrogens were, initially, extracted from water samples into hexane and subsequently, the back extraction stage was performed with 6 μL of sodium... 

    Modelling of mean drop size in a extraction spray column and developing a new model

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 30, Issue 4 , 2011 , Pages 89-96 ; 10219986 (ISSN) Ghorbanian, S. A ; Abolghasemi, H ; Radpour, S. R ; Sharif University of Technology
    Drop size distribution plays a key role in the liquid extraction systems and related hydrodynamic and mass transfer parameters. In current research work, the size of drops in an extraction spray column has been measured by direct photography method, and the Sauter mean diameter has been obtained accordingly. Then, two types of models are assessed based on using dimensionless analysis and appropriate software. The interfacial tension in used chemical system is 1.8-32 dyne/cm. In first type of models, the correlation is established based on dimensionless parameters similar to approaches defined by other researchers. In second types, dimensional parameters have been used and therefore a new... 

    Effect of the reactance term on the charge/discharge electrical measurements using cylindrical capacitive probes

    , Article Journal of Applied Sciences ; Volume 11, Issue 18 , 2011 , Pages 3293-3300 ; 18125654 (ISSN) Behzadi, G ; Fekri, L ; Golnabi, H ; Sharif University of Technology
    In this study, operation of the contact Cylindrical Capacitive Sensor (CCS) for the reactance capacitance measurement of the water liquids by using the charge/discharge measurement module is investigated. The effect of geometric factor on the capacitance measurement of different liquid samples is also studied. The measured capacitances for the distilled, mineral, tap and salt water samples are reported by using two contact CCSs with the active length of 16 and 74 mm. The measured capacitances by small contact CCS for the saltwater is 1.76 uF and by big contact CCS is 47.8 uF, which shows a big difference for different probes. In another study, the effects of the liquid conductance on the... 

    Size dependence and effect of potential parameters on properties of nano-cavities in liquid xenon using molecular dynamics simulation

    , Article Chemical Physics ; Volume 381, Issue 1-3 , March , 2011 , Pages 44-48 ; 03010104 (ISSN) Akbarzadeh, H ; Abroshan, H ; Taherkhani, F ; Izanloo, C ; Parsafar, G. A ; Sharif University of Technology
    We have investigated the size dependence of a nano-cavity properties produced in a Xe fluid using molecular dynamics simulations. We have created a nano-cavity of different sizes at 170 and 200 K (cavities diameters are within 1-10 nm). Liquid pressure, vapor pressure and surface tension of the nano-cavity for some given values of diameter are calculated. Within 1-10 nm cavity diameter, we have observed two opposite behavior for dependency of surface tension on the cavity diameter: for the range of 1-5 nm, it increases with the diameter, while, for the range of 5-10 nm remains constant. Also, the value of liquid pressure becomes less negative, when the size of cavity increases. Vapor... 

    Grain refinement of AA5754 aluminum alloy by ultrasonic cavitation: Experimental study and numerical simulation

    , Article Metals and Materials International ; Volume 21, Issue 1 , 2015 , Pages 109-117 ; 15989623 (ISSN) Haghayeghi, R ; Ezzatneshan, E ; Bahai, H ; Sharif University of Technology
    Korean Institute of Metals and Materials  2015
    In this work, an experimental investigation was carried out on the grain refinement of molten AA5754 Aluminum alloy through ultrasonic treatment. The cavitation induced heterogeneous nucleation was suggested as the major mechanism for grain refinement in the AA5754 aluminum alloy. A numerical simulation was performed to predict the formation, growth and collapse of cavitation bubbles in the molten AA5754 Aluminum alloy. Moreover, the acoustic pressure distribution and the induced acoustic streaming by ultrasonic horn reactor were investigated. It is suggested that the streaming by ultrasonic could transport the small bubbles formed in the ultrasonic cavitation zone into the bulk of melt... 

    Solvatochromic parameters for binary mixtures of an ionic liquid with various protic molecular solvents

    , Article Monatshefte fur Chemie ; Volume 140, Issue 3 , 2009 , Pages 329-334 ; 00269247 (ISSN) Khodadadi Moghaddam, M ; Habibi Yangjeh, A ; Gholami, M. R ; Sharif University of Technology
    Solvatochromic parameters (E T N , normalized polarity parameter; π, dipolarity/polarizability; β, hydrogen-bond acceptor basicity; α, hydrogen-bond donor acidity) have been determined for binary mixtures of propan-2-ol, propan-1-ol, ethanol, methanol and water with recently synthesized ionic liquid (IL; 2-hydroxyethylammonium formate) at 25 °C. In all solutions except aqueous solution, E T N values of the media increase abruptly with the ILs mole fraction and then increase gradually to the value of pure IL. A synergistic behavior is observed for the α parameter in all solutions. The behavior of π and β are nearly ideal for all solutions except for solutions of methanol with the IL. The... 

    CFD modeling of gas-liquid hydrodynamics in a stirred tank reactor

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 26, Issue 2 , 2007 , Pages 85-96 ; 10219986 (ISSN) Gorji, M ; Bozorgmehry Bozzarjomehry, R ; Kazemeini, M ; Sharif University of Technology
    Multiphase impeller stirred tank reactors enhance mixing of reacting species used in a variety of chemical industries. These reactors have been studied based on Computational Fluid Dynamics (CFD) that can be used in the analysis, design and scale up of these reactors. Most of the researches done in this area are limited to single phase reactors, and a few remaining two phase flow investigations have been done based on MRF (Multi Reference Frame) and Snapshot approach. However, the MRF and snapshot approaches cannot be used in rigorous simulation of unsteady state problems. In order to simulate the unsteady state behavior of the multiphase stirred tank reactors we have used sliding mesh... 

    Design and operation of a fiber optic sensor for liquid level detection

    , Article Optics and Lasers in Engineering ; Volume 41, Issue 5 , 2004 , Pages 801-812 ; 01438166 (ISSN) Golnabi, H ; Sharif University of Technology
    Design and construction of an optical fiber sensor for liquid level detection are reported. This sensor operates based on light intensity modulation, and such modulation results from alteration of total internal reflection into partial reflection at the interface. The modulated intensity has been measured by using a pair of fibers, one transmitting source light, another acting as receiving fiber, and a glass prism providing the total and partial reflections. During the level measurements, when a liquid in a vessel touches the 45° faces of the 45-90-45° prism, the total internal reflection is disturbed, and the reflected light is modulated. The performance of this sensor is tested with... 

    Accurate liquid-volume calculations for pure polar compounds using a volume-translated Peng-Robinson equation of state

    , Article Scientia Iranica ; Volume 6, Issue 5 , 2000 , Pages 115-124 ; 10263098 (ISSN) Ghotbi, C ; Behzadi, B ; Feyzi, F ; Sharif University of Technology
    Sharif University of Technology  2000
    In this paper, the accuracy of Peng-Robinson equation of state for vapor-liquid equilibrium calculations has been studied for pure polar compounds and is compared with some other equations of state. This equation has then been modified using the volume-translation technique to improve saturated liquid-volume predictions in low to intermediate temperature and pressure ranges. Two different generalized forms of the translation parameter have been proposed in terms of critical compressibility factor and the reduced dipole moment multiplied by the acentric factor. The proposed generalized equations demonstrate more accurate results compared with the original Peng-Robinson and other selected... 

    Extraction conditions for removal of oxidized sulfur compounds in gas oil

    , Article Korean Journal of Chemical Engineering ; Volume 30, Issue 3 , 2013 , Pages 700-705 ; 02561115 (ISSN) Heidari, M ; Safekordi, A. A ; Ghaedian, M ; Shafeghat, A ; Sharif University of Technology
    An experimental study was conducted to investigate the extraction of oxidized sulfur compounds from gas oil. Solvents used for this purpose included acetone, acetonitrile, methanol and propanol. The effect of solvent concentration, solvent to gas oil ratio, temperature, time and number of stages was studied. To select the best solvent and conditions for extraction, two criteria were considered: high desulfurization and more hydrocarbon recovery. Results showed that extraction time and temperature have no significant effect. Methanol for low ability of extraction of oxidized sulfur compounds and propanol for low hydrocarbon recovery were excluded from further experiments. After the tests, the...