Search for: cobalt
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    Fine-tuning demercaptanization process: A case study

    , Article Hydrocarbon Processing ; Volume 88, Issue 3 , 2009 ; 00188190 (ISSN) Mallaki, Z ; Farhadi, F ; Sharif University of Technology
    Gulf Publishing Company  2009

    Enhanced electrochemical activity of Co3O4/Co9S8 heterostructure catalyst for water splitting

    , Article International Journal of Hydrogen Energy ; 2021 ; 03603199 (ISSN) Khan, N. A ; Ahmad, I ; Rashid, N ; Zafar, M. N ; Shehzad, F. K ; ullah, Z ; Ul-Hamid, A ; Nazar, M.F ; Junaid, M ; Faheem, M ; Shafqat, S. S ; Jabeen, U ; Dahshan, A ; Sharif University of Technology
    Elsevier Ltd  2021
    The dearth of efficient, robust, and economical electrocatalysts for water oxidation is dubiously the key obstacle for renewable energy devices, so synthesis of efficient, and cost-effective metal-based water oxidation catalysts is vital. Herein, Co3O4, Co9S8 catalysts and their heterostructure Co3O4/Co9S8 were synthesized and evaluated as water oxidation electrocatalysts. The characterization of Co3O4, Co9S8, and Co3O4/Co9S8 electrocatalysts was performed using Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction techniques. The heterostructure Co3O4/Co9S8 (1.46 V) exhibited water oxidation electrocatalysis at extremely low onset potential compared to... 

    Optimization of the magnetic properties and microstructure of Co 2+-La3+ substituted strontium hexaferrite by varying the production parameters

    , Article Ceramics International ; Vol. 40, issue. 4 , May , 2014 , pp. 5675-5680 ; ISSN: 02728842 Nourbakhsh, A. A ; Vahedi, A ; Nemati, A ; Noorbakhsh, M ; Mirsatari. S. N ; Shaygan, M ; Mackenzie, K. J. D ; Sharif University of Technology
    The aim of this paper was to improve the magnetic properties of magnetoplumbite-type (M-type) strontium hexaferrite substituted with Co 2+-La3+ produced by conventional ceramic forming techniques. The effect on the magnetic properties of varying the composition of the target compound Sr1-xLaxFe12-yCo yO19 and the primary and secondary firing temperatures was investigated. Microstructure studies and XRD phase analysis indicated that optimum values of the remanent magnetization Br and coercive field Hcj were obtained with a primary firing temperature of 1240 C and a final firing temperature of 1180 C, where (x=y)th 1=0.15, (y/x)exp 2=0.75 and the molar ratio of ferric oxide to strontium... 

    Study on electrowinning of cobalt by cyclic voltammetry technique

    , Article Iranian Journal of Materials Science and Engineering ; Volume 7, Issue 2 , 2010 , Pages 45-48 ; 17350808 (ISSN) Nusheh, M ; Yoozbashizadeh, H ; Sharif University of Technology
    Nowadays cobalt is mostly produced through the electrowinning process of sulfate solutions. Regarding to the competition between the precipitation of cobalt ions and evolution of hydrogen gas on the cathode surface during the reduction process in a sulfate bath, investigation on the mechanism of metal precipitation is of great importance. In the present work, study on the kinetics of cobalt electrowinning and the mechanism of the involved reactions have been carried out. The obtained results, confirm the mechanism of cobalt precipitation by depletion of hydroxides. The effects of temperature and scan rate parameters were studied on electrowinning of cobalt by cyclic voltammetry technique.... 

    Growth behavior of the electrodeposited Co-Ni alloy nanowires

    , Article International Journal of Modern Physics B ; Volume 22, Issue 18-19 , 2008 , Pages 3013-3022 ; 02179792 (ISSN) Ghahremaninezhad, A ; Dolati, A ; Kazemeini, M ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2008
    The Co-Ni alloy nanowires were electrodeposited into porous anodic aluminum oxide (AAO) templates. At the first, highly ordered AAO templates were synthesized by two-step anodizing of aluminum to increase pore ordering. Arrays of nanowires with diameter about 30 nm and length about 5000 nm were electrodeposited by alternating current. The composition and structure property of nanowires were investigated by EDX, SEM and TEM techniques. It was found that nanowire composition was related to ions concentration in solution and it was shown that at the optimum potential range of electrodeposition (17-19 V), a change at the potential was shown no strong effect on chemical composition of nanowires.... 

    Oxidation of thiols to bisulfides by oxygen in presence of cobalt(ii) and manganese(ii) salts of 4-aminobenzoic acid supported on silica gel

    , Article Monatshefte fur Chemie ; Volume 135, Issue 1 , 2004 , Pages 41-43 ; 00269247 (ISSN) Hashemi, M. M ; Karimi Jaberi, Z ; Sharif University of Technology
    A mixture of cobalt(II) and manganese(II) salts of 4-aminobenzoic acid supported on silica gel catalyses the oxidation of thiols to disulfides in the presence of oxygen or air  

    Cobalt and Manganese Salts of p-Aminobenzoic Acid Supported on Silica Gel: A Versatile Catalyst for Oxidation by Molecular Oxygen

    , Article Monatshefte fur Chemie ; Volume 134, Issue 3 , 2003 , Pages 411-418 ; 00269247 (ISSN) Hashemi, M. M ; Ahmadibeni, Y ; Sharif University of Technology
    A 1:1 molar ratio of the cobalt and manganese salts of p-amino benzoic acid supported on silica gel is an effective catalyst for the oxidation of various organic compounds in reasonable yields using molecular oxygen. The catalyst can be reused several times  

    Novel unsymmetrical tetradentate Schiff base complexes of cobalt (II) and palladium (II) with N2O2 donor sets

    , Article Journal of Chemical Research - Part S ; Issue 6 , 2001 , Pages 224-226 ; 03082342 (ISSN) Boghaei, D. M ; Mohebi, S ; Sharif University of Technology
    The novel unsymmetrical tetradentate Schiff base complexes of Co(II) and Pd(II) with the general formula M(SaI.Phen.Acac.) and M(Sal.Phen. Naph.), have been synthesised by template and non-template method  

    Intensified photodegradation of nitrobenzene using ZnO-anchored spinel cobalt ferrite: Environmental application, mechanism, and degradation pathway

    , Article Journal of Water Process Engineering ; Volume 49 , 2022 ; 22147144 (ISSN) Ahmadi, M ; Moslemzadeh, M ; Naderi, A ; Zehtab Salmasi, M ; Harati, M ; Rezaei Kalantary, R ; Kakavandi, B ; Sharif University of Technology
    Elsevier Ltd  2022
    Aromatic and cyclic organic compounds such as nitrobenzene (NB) are widely used in various industries and are present in their wastewater. In addition, the photocatalytic process has received considerable attention due to its lower chemical consumption and more efficient degradation of refractory pollutants. In this study, a CoFe2O4-ZnO (CFZ) composite was prepared and evaluated its efficiency in the degradation of NB from aqueous solution under UV light. The optical, structural, and physicochemical properties of catalysts were characterized using PL, UV–vis DRS, XRD, TEM, FESEM-EDS, and VSM techniques and then discussed in detail. It was found that not only does the use of CF facilitate the... 

    Studying Supercapacitive Performance of Cobalt-based Hierarchical Nanostructures

    , M.Sc. Thesis Sharif University of Technology Afsahi, Nikan (Author) ; Naseri, Naimeh (Supervisor)
    One of the pillars of reaching a steady development is to utilize sustainable energies. In order to make use of these modern means of energy, appropriate energy storage devices are inevitable. One of the families of these devices is the supercapacitors. Moving toward the 4th industrial revolution, we are encountering modern technologies such as internet of things and wearable electronics. Therefore, designing and fabricating microsupercapacitors is of paramount importance in order to reduce the weight and size of these devices. Cobalt and nickel are considered as two important elements to be used in synthesizing supercapacitive materials and composites, because of their good electrochemical... 

    Oxidative Addition of Amines to Aldehydes Catalyzed by Supported Cobalt Nanoparticles on SBA-15

    , M.Sc. Thesis Sharif University of Technology Raeisi, Mojdeh (Author) ; Saidi, Mohamad Reza (Supervisor) ; Rajabi, Fatemeh (Co-Advisor)
    Considering the widespread applications of amides, synthesis of these compounds is of great importance. The one pot oxidative addition of amines to aldehydes is one of the most simple and appealing approaches to synthesis amides. With the aim of developing a mild and convenient approach towards preparation of amides, numerous methods have been reported for this important process over the past few decades. These improvements have been mostly related to the optimization of reaction conditions and the use of more challenging substrates including diverse derivatives of aldehydes, and also design a novel and effective catalytic systems. Due to the various advantages of supported heterogeneous... 

    , M.Sc. Thesis Sharif University of Technology Baradaran Mohajeri, Saha (Author) ; Dolati, Abolghasem (Supervisor)
    Electrodeposition of composite coatings containing nano particles is very important because this technique is simple and economic. In this research, in order to produce a coating with high hardness and wear resistance, Ni-Co/WC nano composite was co-deposited. Watt’s based bath containing cobalt and tungsten carbide was used and parameters such as preparation of solution, concentration of ingredients and current density were controlled and adjusted. Surface morphology, microstructure and mechanical properties of coatings were studied by SEM and AFM microscopes. Mechanism of electrodeposition was investigated by cyclic voltametry, cronoamperometry and cronopotentiometry techniques and... 

    Effect of lanthanum doping on the lifetime of Co/γ-Al 2O 3 catalysts in Fischer-Tropsch synthesis

    , Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 43, Issue 5 , September , 2012 , Pages 704-710 ; 18761070 (ISSN) Hemmati, M. R ; Kazemeini, M ; Zarkesh, J ; Khorasheh, F ; Sharif University of Technology
    Elsevier  2012
    Cobalt-based catalysts were prepared on gamma alumina supports, and their behaviour for different Fischer-Tropsch synthesis (FTS) conditions was assessed. Although Co/γ-Al 2O 3 is a well-known FTS catalyst, its durability ought to be improved to make the industrial process economically feasible. The effect of lanthanum doping on the catalyst lifetime was examined utilising reactor tests and catalyst characterization techniques including TPR, ICP and N 2 porosimetry. Reactor test results revealed that an optimum amount of lanthanum improved catalyst activity and selectivity. Increasing amounts of lanthanum doping up to about 1.1wt% seemed to modify the chemical composition of the support... 

    Separation and recovery of cobalt catalyst from wastewater of PTA unit

    , Article Reviews in Inorganic Chemistry ; Volume 29, Issue 3 , 2009 , Pages 171-179 ; 01934929 (ISSN) Sajadi, S. A. A ; Abdolahifar, A ; Jafarbegloo, M ; Sharif University of Technology
    The goal of this work is separation and recovery of catalyst residue in wastewater and byproducts of PTA (poly terephetalic acid) unit. Catalyst recovery consists in separating the maximum amount of catalyst and changing the same into valuable compounds. The PTA unit uses cobalt catalyst for oxidation reactions. The byproducts, which contain catalyst, were burned. In the case of metal oxide recovery in the ashes of waste materials, we could solve the problem of the Petrochemical Company. This new method may help us to recover catalyst from wastewater in PTA unit, after which small amounts of ions may be absorbed on a column filled with special absorbent, in such a way that the wastewater... 

    Simultaneous voltammetric determination of uric acid and ascorbic acid using a carbon-paste electrode modified with multi-walled carbon nanotubes/nafion and cobalt(II)-nitrosalophen

    , Article Electroanalysis ; Volume 19, Issue 21 , 2007 , Pages 2234-2242 ; 10400397 (ISSN) Shahrokhian, S ; Zare Mehrjardi, H. R ; Sharif University of Technology
    A composition of multiwalled carbon nanotube (MWCNT), Nafion and cobalt(II)-5-nitrosalophen (CoNSal) is applied for the modification of carbon-paste electrode (CPE). The pretreated MWCNT is well dispersed in the alcoholic solution of Nafion under the ultrasonic agitation, and the resulted suspension is used as modifier (with 10% w/w) in the matrix of the paste electrode. The prepared electrode further modified by addition of 3 wt% of CoNSal. The resulted modified electrode is used as a sensitive voltammetric sensor for simultaneous determination of uric acid (UA) and ascorbic acid (AA). The electrode showed efficient electrocatalytic activity in lowering the anodic overpotentials and... 

    3D flower-like nickel cobalt sulfide directly decorated grassy nickel sulfide and encapsulated iron in carbon sphere hosts as hybrid energy storage device

    , Article Applied Surface Science ; Volume 558 , 2021 ; 01694332 (ISSN) Shahi, M ; Hekmat, F ; Shahrokhian, S ; Sharif University of Technology
    Elsevier B.V  2021
    Developing high-performance supercapacitors is of great significance in the area of renewable energies by virtue of having both high energy and power densities. In this work, an innovative strategy is employed for the fabrication of binder-free binary nickel–cobalt-sulfide (NCS) nanosheets (NSs) directly decorated onto the hydrothermal nickel-sulfide (Ni3S2) nanowires (NWs) as the positive electrodes. The NCS/Ni3S2-nickel foam (NF) positive electrodes rendered superior specific capacity of 499.1 mAh.g−1 at 6 A.g−1. Encapsulated iron into the carbon sphere hosts (Fe-HTCSs) are used as the negative counterparts, exhibiting remarkable specific capacitance of 336.6 F.g−1 (at 0.1 A.g−1). The... 

    Electrocatalytic oxidation of 2-thiouracil and 2-thiobarbituric acid at a carbon-paste electrode modified with cobalt phthalocyanine

    , Article Electroanalysis ; Volume 16, Issue 11 , 2004 , Pages 915-921 ; 10400397 (ISSN) Shahrokhian, S ; Hamzehloei, A ; Thaghani, A ; Mousavi, S. R ; Sharif University of Technology
    Voltammetric behavior of two mercaptopyrimidine derivatives (2-thiouracil and 2-thiobarbituric acid) has been studied by cyclic voltammetry at a cobalt phthalocyanine (CoPc)-modified carbon-paste electrode. The results of voltammetric determinations showed that the CoPc in the matrix of modified electrode acts as catalyst for electrooxidation of these thiols (RSH), lowering the overpotential of the reaction and significantly increasing the sensitivity for detection of thiols in neutral conditions. The results of voltammetric and polarization measurements in solutions with various pHs were used for prediction of the mechanism of electrocatalytic oxidation at the surface of modified electrode.... 

    Electrocatalytic oxidation of penicillamine at a carbon paste electrode modified with cobalt salophen

    , Article Journal of Electroanalytical Chemistry ; Volume 565, Issue 1 , 2004 , Pages 95-101 ; 15726657 (ISSN) Shahrokhian, S ; Souri, A ; Khajehsharifi, H ; Sharif University of Technology
    Elsevier  2004
    Electrocatalytic oxidation of penicillamine (PA) at a carbon paste electrode chemically modified with cobalt salophen as a schiff base complex (CoSal) was thoroughly investigated. The results of cyclic voltammetry (CV) and polarization studies were used for the prediction of the mechanism of electrochemical oxidation of PA mediated with CoSal at the surface of a modified electrode. The performance of the modified electrode was compared with those of electrodes modified with cobalt phthalocyanine (CoPc). In comparison, CoSal appears to be considerably more effective as a catalyst for reduction of the overpotential of the anodic oxidation of PA, resulting in a very sharp anodic CV peak at... 

    Epoxidation of terminal olefins by oxygen catalysed by a mixture of manganese and cobalt salts of p-aminobenzoic acid supported on silica gel

    , Article Journal of Chemical Research - Part S ; Issue 10 , 2003 , Pages 662-663 ; 03082342 (ISSN) Hashemi, M. H ; Khoshabro, D. K ; Sharif University of Technology
    Scientific Reviews Ltd  2003
    A mixture of cobalt and manganese salts of p-aminobenzoic acid supported on silica gel catalyses the epoxidation of terminal olefins to the corresponding 1,2-epoxy compounds in the presence of oxygen  

    Voltammetric determination of thiocytosine based on its electrocatalytic oxidation on the surface of carbon-paste electrode modified with cobalt schiff base complexes

    , Article Journal of Solid State Electrochemistry ; Volume 11, Issue 8 , 2007 , Pages 1133-1138 ; 14328488 (ISSN) Shahrokhian, S ; Amiri, M ; Sharif University of Technology
    The electrochemical oxidation of thiocytosine on the surface of carbon-paste electrode modified with Schiff base (salophen derivatives) complexes of cobalt is studied. The effect of the substituents in the structure of salophen on the catalytic property of the modified electrode is investigated by using cyclic and differential pulse voltammetry. Cobalt (II)-5-nitrosalophen, because of its electrophilic functional groups, leads to a considerable enhancement in the catalytic activity, sensitivity (peak current), and a marked increase in the anodic potential of the modified electrode. The differential pulse voltammetry is applied as a very sensitive method for the detection of thiocytosine. The...