Loading...
Search for: ammonium-compounds
0.007 seconds
Total 45 records

    Breakthrough curves for adsorption and elution of rhenium in a column ion exchange system

    , Article Hydrometallurgy ; Volume 85, Issue 1 , 2007 , Pages 17-23 ; 0304386X (ISSN) Mozammel, M ; Sadrnezhaad, S. K ; Badami, E ; Ahmadi, E ; Sharif University of Technology
    2007
    Abstract
    Impure rhenium and molybdenum bearing solution was passed through a column of Varian strong base anionic resin for selective adsorption of rhenium and molybdenum ions from the solution. Elution of molybdenum and rhenium was carried out using 2 N NaOH and 0.2 N NH4SCN, respectively. The effect of resin bed height on breakthrough time was investigated. Experimental and theoretical curves were compared with good agreement. The results showed that the behavior pattern of these curves was repeatable and almost constant. © 2006 Elsevier B.V. All rights reserved  

    Investigation of the reaction of allyl(cyclopentadienyl)iron(II) dicarbonyl with iminium salts: Synthesis of ammonium salts of substituted five-membered-ring iron complexes

    , Article Organometallics ; Volume 26, Issue 1 , 2007 , Pages 201-203 ; 02767333 (ISSN) Ipaktschi, J ; Ziyaei Halimehjani, A ; Saidi, M. R ; Sharif University of Technology
    2007
    Abstract
    Series of quaternary ammonium salts of substituted five-membered-ring iron complexes were prepared by reaction of allyl(cyclopentadienyl)iron(II) dicarbonyl with iminium salts. Also, reactions of allyl-(cyclopentadienyl) iron(II) dicarbonyl with in situ prepared iminium salts afford the same products in good to excellent isolated yields. © 2007 American Chemical Society  

    Using nucleators to control freckles in unidirectional solidification

    , Article Experimental Thermal and Fluid Science ; Volume 33, Issue 8 , 2009 , Pages 1209-1215 ; 08941777 (ISSN) Shafii, M. B ; Alavi Dehkordi, E ; Esmaily Moghadam, M ; Mohseni Koochesfahani, M ; Sharif University of Technology
    2009
    Abstract
    Buoyancy-induced fluid flow, which is responsible for most forms of macro-segregation and channel-type segregates in castings, is not directly controllable. If left uncontrolled, natural convection will contribute to non-uniform distribution of alloy constituents and grain structure during solidification of a casting. Non-uniform distribution of chemical composition and physical structure in an alloy casting can significantly affect the reliability of mechanical components. Therefore, materials with acceptable defects can be produced only by trial-and-error and their acceptability is determined by costly inspections. We present a novel technique to control the formation of chimneys and... 

    Novel one-pot, three-component synthesis of new 2-alkyl-5-aryl-(1H)- pyrrole-4-ol in water

    , Article Journal of Organic Chemistry ; Volume 73, Issue 6 , 2008 , Pages 2090-2095 ; 00223263 (ISSN) Khalili, B ; Jajarmi, P ; Eftekhari Sis, B ; Hashemi, M. M ; Sharif University of Technology
    2008
    Abstract
    (Chemical Equation Presented) New 2-alkyl-5-aryl-(1H)-pyrrole-4-ol derivatives were synthesized via three-component reaction of β-dicarbonyl compounds with arylglyoxals in the presence of ammonium acetate in water at room temperature. © 2008 American Chemical Society  

    Cobalt salophen-modified carbon-paste electrode incorporating a cationic surfactant for simultaneous voltammetric detection of ascorbic acid and dopamine

    , Article Sensors and Actuators, B: Chemical ; Volume 121, Issue 2 , 2007 , Pages 530-537 ; 09254005 (ISSN) Shahrokhian, S ; Zare Mehrjardi, H. R ; Sharif University of Technology
    2007
    Abstract
    A carbon-paste electrode (CPE) is modified by incorporating cobalt-5-nitrosalophen (CoNSal) and tetraoctylammonium bromide (TOAB). The mechanism of electrocatalytic oxidation of dopamine (DA) and ascorbic acid (AA) at the surface of the CoNSal-modified CPE containing various percents of TOAB is thoroughly investigated by cyclic and differential pulse voltammetry. In solutions of pH 5.0, in which all studies are performed, DA exists as the positively charged species whereas AA is mainly as the neutral form. Therefore, the favorable ionic interaction (electrostatic repulsion) between the cationic form of DA and the cationic surfactant (TOA+) caused increasing the overvoltage for DA and... 

    Synthesis and absorbency of gelatin-graft-poly(sodium acrylate-co- acrylamide) superabsorbent hydrogel with saltand pH-responsiveness properties

    , Article E-Polymers ; 2006 , Pages 1-15 ; 16187229 (ISSN) Pourjavadi, A ; Sadeghi, M ; Mahmodi Hashemi, M ; Hosseinzadeh, H ; Sharif University of Technology
    European Polymer Federation  2006
    Abstract
    In this article, we synthesize a novel gelatin-based superabsorbent hydrogel via graft copolymerization of mixtures of acrylic acid (AA) and acrylamide (AAm) onto gelatin backbones. The polymerization reaction was carried out in an aqueous medium and in the presence of ammonium persulfate (APS) as an initiator and N,N-methylene bisacrylamide (MBA) as a crosslinker. The hydrogel structures were confirmed by FTIR spectroscopy. The effect of grafting variables, i.e. concentration of MBA and APS, AA/AAm weight ratio, and reaction time and temperature, was systematically optimized to achieve a hydrogel with swelling capacity as high as possible. The swelling behavior of these absorbent polymers... 

    Novel sulfobetaine-sulfonic acid-contained superswelling hydrogels

    , Article Polymers for Advanced Technologies ; Volume 16, Issue 9 , 2005 , Pages 659-666 ; 10427147 (ISSN) Kabiri, K ; Faraji Dana, S ; Zohuriaan Mehr, M. J ; Sharif University of Technology
    2005
    Abstract
    Novel hydrogels based on zwitterionic monomer [3-(methacrylamido)propyl] dimethyl (3-sulfopropyl) ammonium hydroxide (MPDSAH) and a strong acid monomer (2-acrylamido-2-methylpropane sulfonic acid, AMPS) were synthesized through solution polymerization under normal conditions to achieve nearly quantitative gel yield. The structure of the gels was confirmed using infrared spectroscopy. Thermal properties were simultaneously studied by differential scanning calorimetry and thermogravimetric analysis (DSC/TGA). The effects of the polymerization variables on the swelling capacity of the products were investigated. It was found that, in a certain range of the monomers mol ratio, increase of AMPS... 

    A very simple method to synthesize nano-sized manganese oxide: An efficient catalyst for water oxidation and epoxidation of olefins

    , Article Dalton Transactions ; Volume 41, Issue 36 , Jul , 2012 , Pages 11026-11031 ; 14779226 (ISSN) Najafpour, M. M ; Rahimi, F ; Amini, M ; Nayeri, S ; Bagherzadeh, M ; Sharif University of Technology
    RSC  2012
    Abstract
    Nano-sized particles of manganese oxides have been prepared by a very simple and cheap process using a decomposing aqueous solution of manganese nitrate at 100 °C. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction spectrometry have been used to characterize the phase and the morphology of the manganese oxide. The nano-sized manganese oxide shows efficient catalytic activity toward water oxidation and the epoxidation of olefins in the presence of cerium(iv) ammonium nitrate and hydrogen peroxide, respectively  

    Adsorption of hydrocarbons on modified nanoclays

    , Article IOP Conference Series: Materials Science and Engineering, 14 November 2010 through 18 November 2010, Osaka ; Volume 18, Issue SYMPOSIUM 12 , 2011 ; 17578981 (ISSN) Sharafimasooleh, M ; Bazgir, S ; Tamizifar, M ; Nemati, A ; Sharif University of Technology
    2011
    Abstract
    In this study organically modified nanoclay were prepared by exchanging of the cetyltrimethylammonium (CTAB), with inorganic/metal ions/cations in montmorillonite structure. To investigate the influence of the amount of modifier on basal spacing and subsequent removal efficiency of hydrocarbon, different amount of modifier was used. The modified and unmodified nanoclays characterized by XRD, CHN and FTIR techniques. The X-ray diffraction results showed that the interlayer spacing of CTAB-modified clays increased from 12 to 22Å. The effectiveness of the sorbent materials for sorption of a range of products was investigated using crude oil, kerosene, gasoline and toluene. The process... 

    Synthesis, characterization and comparison of PAM, cationic PDMC and P(AM-co-DMC) based on solution polymerization

    , Article Journal of Industrial and Engineering Chemistry ; Volume 17, Issue 3 , 2011 , Pages 580-586 ; 1226086X (ISSN) Abdollahi, Z ; Frounchi, M ; Dadbin, S ; Sharif University of Technology
    2011
    Abstract
    High molecular weight homopolymers of acrylamide (PAM) and (2-methacryloyloxyethyl) trimethyl ammonium chloride (PDMC) and copolymer of DMC with acrylamide (P(AM-co-DMC)) were synthesized using solution polymerization technique. The synthesized polymers were characterized by Fourier transform infrared (FTIR), 1HNMR, 13CNMR spectroscopy and differential scanning calorimetry (DSC) and viscometery. 1HNMR and 13CNMR studies confirmed the structure of the synthesized polymers. The behavior of the synthesized polymers was investigated in water-acetone and water-methanol mixtures. The plot of intrinsic viscosity of either PAM or P(AM-co-DMC) with respect to acetone (methanol)/water ratio in... 

    Stereoelectronic effects: A simple yet powerful tool to manipulate anion affinity

    , Article Organic and Biomolecular Chemistry ; Volume 13, Issue 7 , Dec , 2015 , Pages 2170-2176 ; 14770520 (ISSN) Samet, M ; Fattahi, A ; Kass, S.R ; Sharif University of Technology
    Royal Society of Chemistry  2015
    Abstract
    Different strategies are employed in designing strong and selective anion receptors but stereoelectronic effects have been largely ignored. In this work, the stereo configuration of a non-interacting ether is found to have a large impact of more than two orders of magnitude on the binding of a rigid diol with tetrabutylammonium chloride in acetonitrile-d3. A favorable carbon-oxygen dipole and an intramolecular C-H⋯OH hydrogen bond in an equatorially substituted ether is found to be energetically more important than a stabilizing hydrogen bond in the corresponding axially oriented alcohol. IR spectroscopy is also used to probe the structures of the bound complexes and several binding motifs... 

    Heterogeneous water oxidation by bidentate schiff base manganese complexes in the presence of cerium(IV) ammonium nitrate

    , Article Transition Metal Chemistry ; Volume 34, Issue 4 , 2009 , Pages 367-372 ; 03404285 (ISSN) Najafpour, M. M ; Boghaei, D. M ; Sharif University of Technology
    2009
    Abstract
    Oxygen evolution was observed upon mixing solid manganese(III) bidentate Schiff base complexes with aqueous solutions of cerium(IV) ammonium nitrate. However, oxygen evolution was not observed upon mixing solutions of the complexes (in acetonitrile) with Ce(IV). Electron-withdrawing substituents on the Schiff base ligands (NO2, Br) enhanced the reactivity of the manganese complexes toward oxygen evolution. Oxygen evolution was also affected by R groups on the ligands, in the order Me > Et Bz. © 2009 Springer Science+Business Media B.V  

    Novel nanoporous superabsorbent hydrogel based on poly(acrylic acid) grafted onto salep: Synthesis and swelling behavior

    , Article Starch/Staerke ; Volume 60, Issue 9 , 9 September , 2008 , Pages 467-475 ; 00389056 (ISSN) Pourjavadi, A ; Soleyman, R ; Rezanejade Barajee, G ; Sharif University of Technology
    2008
    Abstract
    Hydrogels of poly(acrylic acid) grafted onto salep with excellent water absorption and water retention abilities under neutral conditions were successfully synthesized for the first time and employed for different applications. The effect of reaction variables to achieve maximum swelling capacity was investigated. In our procedure, ammonium persulfate (APS) as a water-soluble initiator and methylenebisacrylamide (MBA) as a suitable crosslinking agent were used and the best synthesis conditions described. The structure of the final product was confirmed by Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy SEM and TGA analysis and a mechanism for superabsorbent... 

    Modified CMC. V. synthesis and super-swelling behavior of hydrolyzed CMC-g-PAN hydrogel

    , Article Journal of Applied Polymer Science ; Volume 103, Issue 2 , 2007 , Pages 877-883 ; 00218995 (ISSN) Pourjavadi, A ; Zohuriaan Mehr, M. J ; Ghasempoori, S. N ; Hossienzadeh, H ; Sharif University of Technology
    2007
    Abstract
    Polyacrylonitrile (PAN) was grafted onto carboxymethyl cellulose (CMC) sodium salt backbones by using cerie ammonium nitrate (CAN) as an initiator. The graft co-polymer, CMC-g-PAN, was hydrolyzed by NaOH solution to yield hydrogel, H-CMC-g-PAN. The nitrile groups of CMC-g-PAN were completely converted to a mixture of hydrophilic carboxamide and carboxylate groups during alkaline hydrolysis, followed by in situ crosslinking of the grafted PAN chains. The structure of the products was confirmed by FTIR spectroscopy. The synthetic parameters affecting the swelling capacity of the hydrogel (i.e., CMC-g-PAN add-on value, the hydrolysis time and temperature, and concentration of NaOH) were... 

    Production of low ester (LM) pectin by de-esterification of high ester (HM) apple pectin

    , Article Scientia Iranica ; Volume 12, Issue 3 , 2005 , Pages 306-310 ; 10263098 (ISSN) Alemzadeh, I ; Saifkordi, A. A ; Kahforooshan, D ; Nahid, P ; Sharif University of Technology
    Sharif University of Technology  2005
    Abstract
    In this paper, LM pectin production from commercial apple pectin by using acid, alkali and ammonia methods in the presence of ethanol was studied. Also, the effect of different parameters such as, temperature, time, acid, alkali and ammonia treatment in LM pectin production were evaluated. In all the experiments, low temperature showed a better influence from a recovery, purity and low de-polymerization viewpoint. Optimum conditions in the acid method reached at pH = 2, t = 17 hrs and T = 30°C, in the alkaline method reached at pH = 11, t = 3 hrs and T = 5°C and in the ammonia method reached at 2 N ammonia and T = 5°C, were determined. © Sharif University of Technology  

    Dextran-graft-poly(hydroxyethyl methacrylate) gels: A new biosorbent for fluoride removal of water

    , Article Designed Monomers and Polymers ; Volume 16, Issue 2 , 2013 , Pages 127-136 ; 1385772X (ISSN) Ahmari, A ; Mousavi, S. A ; Amini Fazl, A ; Amini Fazl, M. S ; Ahmari, R ; Sharif University of Technology
    2013
    Abstract
    Synthesis of dextran-graft-poly(hydroxyethyl methacrylate) gels as a new fluoride biosorbent was considered in this work. For this propose, the Taguchi experimental design method was used for optimizing the synthetic conditions of the gels to reach high level of fluoride absorbency. The effects of three main parameters including concentrations of monomer (hydroxyethyl methacrylate), crosslinking agent (ethylene glycol dimethacrylate), and initiator (ammonium persulfate) on the final properties of the prepared gels were investigated. The proposed mechanism for grafting and chemically crosslinking reactions was proved with equilibrium water absorption, Fourier-transformed infrared, scanning... 

    Size-controlled synthesis of superparamagnetic iron oxide nanoparticles and their surface coating by gold for biomedical applications

    , Article Journal of Magnetism and Magnetic Materials ; Volume 324, Issue 23 , November , 2012 , Pages 3997-4005 ; 03048853 (ISSN) Maleki, H ; Simchi, A ; Imani, M ; Costa, B. F. O ; Sharif University of Technology
    2012
    Abstract
    The size mono-dispersity, saturation magnetization, and surface chemistry of magnetic nanoparticles (NPs) are recognized as critical factors for efficient biomedical applications. Here, we performed modified water-in-oil inverse nano-emulsion procedure for preparation of stable colloidal superparamagnetic iron oxide NPs (SPIONs) with high saturation magnetization. To achieve mono-dispersed SPIONs, optimization process was probed on several important factors including molar ratio of iron salts [Fe 3 and Fe 2], the concentration of ammonium hydroxide as reducing agent, and molar ratio of water to surfactant. The biocompatibility of the obtained NPs, at various concentrations, was evaluated via... 

    Synthesis and characterization of Ce-TZP/Al 2O 3 nanocomposites prepared via aqueous combustion

    , Article Journal of Alloys and Compounds ; Volume 514 , February , 2012 , Pages 150-156 ; 09258388 (ISSN) Asadirad, M ; Yoozbashizadeh, H ; Sharif University of Technology
    2012
    Abstract
    Nanocomposites of Ce-TZP/Al 2O 3 were synthesized by aqueous combustion, and urea, ammonium acetate and glycine were used as mixtures of fuels with the corresponding metal nitrates. Thermodynamic modeling was conducted to anticipate the effect of the alumina content on the exothermicity of the combustion procedure. The thermodynamic properties of the combustion reaction indicated that as the alumina content increased, the amount of gases produced during the reaction increased with a decrease in the adiabatic temperature. Furthermore, to reduce the particle size of the powders, a series of combustion reactions were performed to optimize the fuel composition and alumina content. Ce 0.1Zr 0.9O... 

    Salep-g-poly(sodium acrylate)/alumina as an environmental-sensitive biopolymer superabsorbent composite: Synthesis and investigation of its swelling behavior

    , Article Advances in Polymer Technology ; Volume 31, Issue 1 , 2012 , Pages 41-51 ; 07306679 (ISSN) Bardajee, G. R ; Pourjavadi, A ; Soleyman, R ; Ghavami, S ; Sharif University of Technology
    Abstract
    A novel kind of a biopolymer-based superabsorbent composite, salep-g-poly(sodium acrylate)/alumina, was prepared from salep, sodium acrylate, and alumina by aqueous polymerization, using N,N'-methylenebisacrylamide (MBA) as a cross-linker and ammonium persulfate (APS) as an initiator. The reaction parameters [i.e., acrylic acid (AA), MBA, APS amounts, and neutralization percentage of AA as well as alumina/salep weight ratio] affecting the water absorbency of the hydrogel composite were optimized using systematic method to achieve a composite with high swelling capacity as possible. The swelling behavior of optimum superabsorbent composite was measured in various pH solutions. In addition,... 

    Preparation of acrylated agarose-based hydrogels and investigation of their application as fertilizing systems

    , Article Journal of Applied Polymer Science ; Volume 122, Issue 4 , November , 2011 , Pages 2424-2432 ; 00218995 (ISSN) Pourjavadi, A ; Sadat Afjeh, S ; Seidi, F ; Salimi, H ; Sharif University of Technology
    2011
    Abstract
    In this study, we attempt to synthesize novel acrylated agarose (ACAG)-based hydrogels with three different crosslinking densities. Acrylate groups were inserted onto agarose (AG) backbone through homogeneous reaction of acrylic monomers with AG backbone. Hydrogels were synthesized through radical copolymerization of a mixture of acrylic acid and 2-hydroxyethyl acrylate with ACAG in aqueous solution using ammonium persulfate as an initiator. Infrared spectroscopy (FTIR) was carried out to confirm the chemical structure of the hydrogel. Moreover, morphology of the samples was assessed by scanning electron microscopy. The equilibrium swelling capacities of synthesized hydrogels were evaluated...