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Extraction of ZN, MN and CO from ZN-MN-CO-CD-NI containing solution using D2EHPA, Cyanex® 272 and Cyanex® 302
, Article International Journal of Engineering, Transactions B: Applications ; Volume 24, Issue 2 , 2011 , Pages 183-192 ; 1728-144X (ISSN) ; Haghshenas, D. F ; Alamdari, E. K ; Sadrnezhaad, S. K ; Sharif University of Technology
2011
Abstract
Effects of pH, D2EHPA, Cyanex® 272 and Cyanex® 302 on extraction of zinc, manganese and cobalt from a Zn-Mn-Co-Cd-Ni containing solution at the room temperature was comprehensively investigated. Addition of Cyanex® 302 indicated a left-shifting-effect on the extraction curve of zinc, a right-shifting-effect on the extraction curve of manganese and no effect on the extraction of cobalt. Addition of Cyanex® 272 shifted all three curves to the right. Therefore, the most suitable extractant for separation of zinc from manganese was therefore 0.3-0.3 mixture of D2EHPA and Cyanex® 302, and that for separation of manganese from cobalt was pure D2EHPA. The stoichiometric coefficient for the...
Enhancing biosurfactant production from an indigenous strain of Bacillus mycoides by optimizing the growth conditions using a response surface methodology
, Article Chemical Engineering Journal ; Volume 163, Issue 3 , October , 2010 , Pages 188-194 ; 13858947 (ISSN) ; Rahimpour, M. R ; Jahanmiri, A. H ; Roostaazad, R ; Arabian, D ; Ghobadi, Z ; Sharif University of Technology
2010
Abstract
In this study, we have investigated the potential of a native bacterial strain isolated from an Iranian oil field for the production of biosurfactant. The bacterium was identified to be Bacillus mycoides by biochemical tests and 16S ribotyping. The biosurfactant, which was produced by this bacterium, was able to reduce the surface tension of media to 34. mN/m. Compositional analysis of the produced biosurfactant has been carried out by thin layer chromatography (TLC) and FT-IR. The biosurfactant produced by the isolate was characterized as lipopeptide derivative. Biosurfactant production was optimized by the combination of central composite design (CCD) and response surface methodology...
A study of the electrophoretic deposition of Bioglass® suspensions using the Taguchi experimental design approach
, Article Journal of the European Ceramic Society ; Volume 30, Issue 14 , October , 2010 , Pages 2963-2970 ; 09552219 (ISSN) ; Simchi, A ; Ryan, M. P ; Boccaccini, A. R ; Sharif University of Technology
2010
Abstract
This paper presents a study of the Taguchi design method to optimise the rate of electrophoretic deposition (EPD) of Bioglass® particles from aqueous suspensions. The effect of Bioglass® concentration, pH and electric field was investigated. An orthogonal array of L16 type with mixed levels of the control factors was utilized. Multivariate analysis of variance (MANOVA) and regression analysis based on the partial least-square method were used to identify the significant factors affecting the deposition rate and its stability during constant-voltage EPD. It was found that the pH of the suspension significantly influences the deposition rate whereas the applied electric field has the smallest...
Partitioning of l-lysine monohydrochloride in aqueous two-phase systems of poly(ethylene glycol) and dipotassium hydrogen phosphate or trisodium citrate 5-hydrate
, Article Journal of Chemical and Engineering Data ; Volume 55, Issue 9 , 2010 , Pages 3005-3009 ; 00219568 (ISSN) ; Pazuki, G ; Vossoughi, M ; Alemzadeh, I ; Sharif University of Technology
2010
Abstract
The partition constants of l-lysine HCl were measured in polymer-salt aqueous two-phase systems. These systems contain poly(ethylene glycol) with a nominal molecular weight of 4000 or 10000 and two different salts (dipotassium hydrogen phosphate or trisodium citrate 5-hydrate). The experimental data were obtained at temperatures of (293.15, 298.15, and 303.15) K. The effects of temperature, pH, polymer and salt concentrations, polymer molecular weight, and salt type on the partitioning of l-lysine HCl were also studied. The results showed that salt concentration has a significant effect on the partition constant while temperature has less effect. The Diamond and Hsu model was used to...
Investigation and optimization of SDS and key parameters effect on the nickel electroless coatings properties by Taguchi method
, Article Journal of Coatings Technology Research ; Volume 7, Issue 5 , 2010 , Pages 547-555 ; 15470091 (ISSN) ; Ehteshamzadeh, M ; Ghorbani, M ; Vazifeh Mehrabani, J ; Sharif University of Technology
2010
Abstract
In this research, the influence of anionic surfactant sodium dodecyl sulfate (SDS), pH, substrate finishing, and annealing temperature on the surface morphology and hardness of the electroless nickel phosphorus (ENi-P) coatings were studied. Taguchi's experimental design method was used. Parameters selected in three levels and L9 from orthogonal robust array design were employed. Surface roughnesses of the deposits were measured using a stylus instrument. Scanning electron microscope and x-ray diffraction analysis were implemented to study surface morphologies and phase composition, respectively. Microhardness of the ENi-P deposits was measured using a microhardness tester at three trials...
Degradation of humic acids through heterogeneous catalytic ozonation with bone charcoal
, Article Reaction Kinetics, Mechanisms and Catalysis ; Volume 100, Issue 2 , 2010 , Pages 471-485 ; 18785190 (ISSN) ; Asgari, Gh ; Hashemian, S. J ; Moussavi, G ; Sharif University of Technology
2010
Abstract
Catalytic ozonation has recently been used as a new means of contaminant removal from water and wastewater. In this study, bone charcoal (BC), a new catalyst prepared under laboratory conditions, was used to catalyze the ozonation of humic substances (HS) in aqueous solutions. The catalytic effect of bone charcoal and the relevant parameters of this ozonation process (solution pH, temperature, scavenger effect, humic acids concentration and BC dosage) were investigated. In the catalytic ozonation experiments, the degradation kinetics was investigated. The reaction rate and the rate constant were determined. The results showed that using a BC catalyst in the ozonation of HS produced a 1.43-...
Enzymatic synthesis of amoxicillin with immobilized penicillin G acylase
, Article Scientia Iranica ; Volume 17, Issue 1 C , 2010 , Pages 106-113 ; 10263098 (ISSN) ; Borghei, G ; Vafi, L ; Roostaazad, R ; Sharif University of Technology
2010
Abstract
The synthesis of amoxicillin with immobilized penicillin G acylase (PGA) in aqueous medium was investigated. The parameters studied were: time course of amoxicillin production, concentration of substrates: hydroxyphenylglycine methyl ester (HPGM) and 6-aminopeicillanic acid (6-APA) and the. effect of enzyme (PGA) content and pH, under variable and constant conditions and temperature variations. In the study of two substrate concentration on amoxicillin production, impressive results were obtained for a 1/3 ratio of 6-amino penicillanic acid (6-APA) and hydroxyl-phenylglycine methyl ester (HPGM). The. synthesis of amoxicillin was preferable at constant pH rather than a variable one. Other...
Glassy carbon electrodes modified with a film of nanodiamond-graphite/chitosan: Application to the highly sensitive electrochemical determination of Azathioprine
, Article Electrochimica Acta ; Volume 55, Issue 11 , 2010 , Pages 3621-3627 ; 00134686 (ISSN) ; Ghalkhani, M ; Sharif University of Technology
2010
Abstract
A novel modified glassy carbon electrode with a film of nanodiamond-graphite/chitosan is constructed and used for the sensitive voltammetric determination of azathioprine (Aza). The surface morphology and thickness of the film modifier are characterized using atomic force microscopy. The electrochemical response characteristics of the electrode toward Aza are investigated by means of cyclic voltammetry. The modified electrode showed an efficient catalytic role for the electrochemical reduction of Aza, leading to a remarkable decrease in reduction overpotential and enhancement of the kinetics of the electrode reaction with a significant increase of peak current. The effects of experimental...
Fractional factorial design for the optimization of hydrothermal synthesis of lanthanum oxide nanoparticles under supercritical water condition
, Article Journal of Supercritical Fluids ; Volume 52, Issue 3 , 2010 , Pages 292-297 ; 08968446 (ISSN) ; Abolghasemi, H ; Moosavian, M. A ; Golzary, A ; Ghannadi Maragheh, M ; Sharif University of Technology
2010
Abstract
In this research, synthesis of lanthanum oxide nanoparticles using supercritical water as a reaction medium in batch type reactor was studied. The crystallographic identity and morphology of the synthesized nanoparticles were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD patterns indicate that the well-crystallized lanthanum oxide nanocrystals can be easily obtained under the current synthetic conditions. The effect of four parameters includes temperature, reaction time; primary concentration of aqueous solution of lanthanum (III) nitrate and pH of starting solution on reaction efficiency, particle size and the BET surface area were investigated...
Simultaneous determination of epinephrine and acetaminophen concentrations using a novel carbon paste electrode prepared with 2,2′-[1,2 butanediylbis(nitriloethylidyne)]-bis-hydroquinone and TiO2 nanoparticles
, Article Colloids and Surfaces B: Biointerfaces ; Volume 76, Issue 1 , 2010 , Pages 82-87 ; 09277765 (ISSN) ; Beitollahi, H ; Sheikh Mohseni, M. A ; Benvidi, A ; Naeimi, H ; Nejati Barzoki, M ; Taghavinia, N ; Sharif University of Technology
2010
Abstract
A carbon paste electrode (CPE) modified with 2,2′-[1,2 butanediylbis(nitriloethylidyne)]-bis-hydroquinone (BBNBH) and TiO2 nanoparticles was used for the sensitive voltammetric determination of epinephrine (EP). The electrochemical response characteristics of the modified electrode toward EP and acetaminophen (AC) were investigated by cyclic and differential pulse voltammetry (CV and DPV). The results showed an efficient catalytic activity of the electrode for the electrooxidation of EP, which leads to a reduction in its overpotential by more than 270 mV. The effects of pH and potential sweep rate on the mechanism of the electrode process were investigated. The modified electrode exhibits an...
Application of carbon nanoparticle/chitosan modified electrode for the square-wave adsorptive anodic striping voltammetric determination of Niclosamide
, Article Electrochemistry Communications ; Volume 12, Issue 1 , 2010 , Pages 66-69 ; 13882481 (ISSN) ; Shahrokhian, S ; Sharif University of Technology
2010
Abstract
A new modified electrode formed by carbon nanoparticle/chitosan film (CNP/CS) was used for electrocatalytic reduction of Niclosamide (NA). The electrochemical behavior of NA at the CNP/CS modified electrode was investigated in detail by the means of cyclic voltammetry. The reduction mechanism of NA, corresponds to the redox chemistry of nitro group, was thoroughly investigated. The effect of the experimental parameters e.g. potential and time of accumulation, pH of the buffered solutions and potential sweep rate on the response of the electrode was studied. The prepared electrode showed high stability and uniformity in the composite film, short response time, good reproducibility and an...
Hydrothermal synthesis of ZnO nanorod arrays for photocatalytic inactivation of bacteria
, Article Journal of Physics D: Applied Physics ; Volume 42, Issue 22 , 2009 ; 00223727 (ISSN) ; Mehrabian, M ; Mirabbaszadeh, K ; Azimirad, R ; Sharif University of Technology
2009
Abstract
Arrays of ZnO nanorods were synthesized on ZnO seed layer/glass substrates by a hydrothermal method at a low temperature of 70 °C. The effect of pH > 7 of the hydrated zinc nitrate-NaOH precursor on the morphology and topography (e.g. size, surface area and roughness), the optical characteristics (e.g. optical transmission and band-gap energy), hydrophilicity and antibacterial activity of the grown ZnO nanostructure and nanorod coatings were investigated. For pH = 11.33 of the precursor (NaOH concentration of 0.10M), a fast growth of ZnO nanorods on the seed layer (length of ∼1 νm in 1.5 h) was observed. The fast growth of the ZnO nanorods resulted in a significant reduction in the optical...
Application of carbon-paste electrode modified with iron phthalocyanine for voltammetric determination of epinephrine in the presence of ascorbic acid and uric acid
, Article Sensors and Actuators, B: Chemical ; Volume 137, Issue 2 , 2009 , Pages 669-675 ; 09254005 (ISSN) ; Ghalkhani, M ; Amini, M. K ; Sharif University of Technology
2009
Abstract
A carbon-paste electrode (CPE) modified with iron(II) phthalocyanine was used for the sensitive voltammetric determination of epinephrine (EN). The electrochemical response characteristics of the modified electrode toward EN, ascorbic acid (AA) and uric acid (UA) were investigated by cyclic and differential pulse voltammetry (CV and DPV). The results show an efficient catalytic activity of the electrode for the electro-oxidation of EN, which leads to improvement of reversibility of the electrode response and lowering its overpotential by more than 100 mV. The effect of pH and potential sweep rate on the mechanism of the electrode process was investigated. The modified electrode exhibits an...
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) ; 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...
TiO2 nanofibre assisted photocatalytic degradation of reactive blue 19 dye from aqueous solution
, Article Environmental Technology ; Volume 30, Issue 3 , 2009 , Pages 233-239 ; 09593330 (ISSN) ; Ghaneian, M. T ; Taghavinia, N ; Khajeh Aminian, M ; Hashemian, S. J ; Sharif University of Technology
2009
Abstract
The photocatalytic degradation of Reactive Blue 19 (RB19) dye has been studied using TiO2 nanofibre as the photocatalyst in aqueous solution under UV irradiation. Titanium dioxide nanofibre was prepared using a templating method with tetraisopropylorthotitanate as a precursor. The experiments were carried out in the presence of the TiO2 nanofibre, and the effects of pH and electron acceptors on the degradation process were investigated. In order to observe the quality of the aqueous solution, chemical oxygen demand (COD) measurements were also carried out before and after the treatments. The photocatalytic decomposition of RB19 was most efficient in acidic solution. With the addition of...
Microbial leaching of a low-grade sphalerite ore using a draft tube fluidized bed bioreactor
, Article Hydrometallurgy ; Volume 99, Issue 3-4 , 2009 , Pages 131-136 ; 0304386X (ISSN) ; Hosseini, S ; Roostaazad, R ; Petersen, J ; Mousavi, M ; Kazemi Vasiri, A ; Sharif University of Technology
2009
Abstract
The use of a draft tube fluidized bed bioreactor (DTFBB) has been successfully demonstrated for the bioleaching of a chalcopyrite concentrate (Mousavi, et. al., 2005). In the present paper this technique was used for the bioleaching of zinc from a sphalerite bearing low-grade ore. A strain of the thermophilic bacterium, Sulfobacillus, has been isolated from the Kooshk lead and zinc mine near the city of Yazd (Iran) and is tested at temperatures 47 °C-72 °C. This is compared to leaching with a strain of the mesophile Acidithiobacillus ferrooxidans, which has been adapted to the high levels of zinc and the presence of the low-grade ore, and which was tested at temperatures 18 °C-42 °C. The...
Effective factors in the treatment of kerosene-water emulsion by using UF membranes
, Article Journal of Hazardous Materials ; Volume 161, Issue 2-3 , 2009 , Pages 1216-1224 ; 03043894 (ISSN) ; Roostaazad, R ; Hesampour, M ; Nyström, M ; Ghotbi, C ; Sharif University of Technology
2009
Abstract
The effects of different parameters including membrane type (regenerated cellulose and polysulphone), transmembrane pressure (TMP), the content of oil in the feed, the flow velocity of the feed and pH on the ultrafiltration of an emulsion of kerosene in water were studied. It was found that the important factors affecting ultrafiltration were, in order, membrane type, pressure and oil concentration. The greatest flux at the optimum conditions here of 3 bar, an oil content of 3% (v/v) and with membrane type C30F was predicted as 108 L/(m2 h) that was within the range of the confidence limit of the measured value of 106 L/(m2 h). The normalised FTIR results of the virgin cellulosic membranes...
Properties of alumina nanoparticle-filled nitrile-butadiene-rubber/ phenolic-resin blend prepared by melt mixing
, Article Polymer Composites ; Volume 30, Issue 9 , 2009 , Pages 1290-1298 ; 02728397 (ISSN) ; Shojaei, A ; Sharif University of Technology
2009
Abstract
Effect of alumina nanoparticle (ANP) on the properties of rubber compounds based on nitrile-butadiene-rub- ber (NBR) and NBR/phenolic-resin (PH) blend is examined. To investigate the surface characteristics of the nanoparticles on the performance of nanoalumina- filled compounds, trimethoxyvinylsilane (MVS) is attached chemically on the surface of ANP through an appropriate functionalization process. Various NBR and NBR/Ph compounds filled with ANP and functionalized ANP (f-ANP) are prepared via melt mixing using traditional open two-roll mill. Microscopic analysis carried out by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) reveals good dispersion of...
Measurement and modeling process partitioning of cephalexin antibiotic in aqueous two-phase systems containing poly(ethylene glycol) 4000, 10000 and K2HPO4, Na3Citrate
, Article Journal of Chemical and Engineering Data ; Volume 54, Issue 8 , 2009 , Pages 2239-2244 ; 00219568 (ISSN) ; Pazuki, G. R ; Taghikhani, V ; Vossoughi, M ; Ghotbi, C ; Sharif University of Technology
2009
Abstract
In this work, the partition coefficients of Cephalexin in aqueous two-phase systems containing PEG [poly(ethylene glycol)] 4000, 10000 and K 2HPO4, Na3Citrate (C6H 5Na3O7 5, 5H2O) have been measured. The experimental data were obtained in a wide range of temperatures, (28.2 to 37.2) °C. The effects of temperature, pH, polymer concentration, polymer molecular weight, and salt concentration on the partitioning of Cephalexin were also studied. The results showed that salt concentration has a large effect on the partition coefficient, and temperature has an almost negligible effect. The Chen-NRTL Gibbs energy model was used to correlate the experimental results. © 2009 American Chemical Society
Interaction between TBP and D2EHPA during Zn, Cd, Mn, Cu, Co and Ni solvent extraction: A thermodynamic and empirical approach
, Article Hydrometallurgy ; Volume 98, Issue 1-2 , 2009 , Pages 143-147 ; 0304386X (ISSN) ; Darvishi, D ; Etemadi, S ; Eivazi Hollagh, A. R ; Keshavarz Alamdari, E ; Salardini, A. A ; Sharif University of Technology
2009
Abstract
The objective of this study was to investigate the synergistic effect of TBP on the system D2EHPA/kerosense/M2+ with respect to the extraction of some transitional metals. Although the presence of M2EHPA as an impurity in D2EHPA shifts the extraction curves to lower pH, empirical results show that the extraction curves shift to the right due to the addition of TBP and the counterbalance effect of M2EHPA. The results indicate that the equivalent concentration of D2EHPA decreases as a function of concentration of TBP because of the formation of hydrogen bonds between TBP and D2EHPA. Based on this finding, the D2EHPA equivalent concentration was determined by using a modifying factor for TBP...