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alkaline-solutions
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Experimental Study of Oxygen Reduction Reaction (ORR) on Cu-alloys, Electrocatalysts in Alkaline Solution and Theoretical Investigation of Oxygen Adsorption on Cu-alloys Nano-clusters
, Ph.D. Dissertation Sharif University of Technology ; Gobal, Fereydoon (Supervisor)
Abstract
In this study, electrochemical oxygen reduction reaction (ORR) was studied on Cu, Pd, Rh, Pd-Cu and Rh-Cu alloys in alkaline solution. Pd-Cu and Rh-Cu alloys were prepared by electrochemical methods. On copper electrode it is found that direct oxygen reduction is accompanied by the electrochemical reductions of copper oxides. Also, mechanism and kinetics of reaction change as the amount of copper oxides increase on the surface. For electrodeposited alloys, it is indicated that the reactivity of Pd-Cu and Rh-Cu alloys toward oxygen reduction is higher than pure Pd and pure Rh. The maximum reactivity among Pd-Cu alloys is related to the sample with 24.5% copper content while the maximum...
The Poisoning Effect of Sulfur-Containing Compounds on the Elelctro-Oxidation of Methanol and Ethanol on Ni and Cu Electrodes
, M.Sc. Thesis Sharif University of Technology ; Gobal, Fereydon (Supervisor)
Abstract
In this study a systematic effort was made to investigate the poisoning effect of sulfur-containing materials on the electro- oxidation of methanol and ethanol on Ni and Cu electrodes in alkaline solutions by the methods of cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. Activation energy of methanol electro-oxidation in the absence of Na2S was obtained 30.7 kJ/mol by cyclic voltammetric at different temperatures, and its values increased by increase in Na2S concentrations to 97kJ/mol. Na2S adsorption isotherms corresponded with Langmuire isotherm, equilibrium constants of adsorption – desorption and adsorption enthalpy (ΔHads= -62kJ/mol) were calculated for...
Experimental Investigation of the Durability of Rammed Earth Materials in Different Environments
, M.Sc. Thesis Sharif University of Technology ; Toufigh, Vahab (Supervisor)
Abstract
Rammed earth structures have attracted the attention of engineers and researchers in recent years due to their economic advantages, sustainable development, and environmental sustainability. One of the main concerns for public opinion for acceptance of Rammed Earth as a reliable construction material is their durability. Previous studies have investigated the durability of rammed earth materials by conducting wet and dry cycle test, accelerated erosion test, and rain simulation in the laboratory environment. This research studied the durability of cement stabilized rammed earth (CSRE) for one year under the aggressive environments. Three cement contents were considered for preparing the CSRE...
Mechanical Characteristics of Activated Slag Concrete with Alkaline Solution
, M.Sc. Thesis Sharif University of Technology ; Kazemi, Mohammad Taghi (Supervisor)
Abstract
Nowadays, due to the increasing importance of environmental issues, cement replacement has been considered by many researchers .Determination of behavioral characteristics and fracture of materials such as fracture hardness and energy is used to describe the formation and progress of cracks in new building materials. On the other hand, one of the concrete that can be replaced ordinary concrete is slag concrete. Slag concrete is in the category of Geopolymer Concrete. This concrete is produced by activation of puzzulanic material by alkaline solution.There have not been many studies on the failure of slag concrete. Therefore, in this study, the mechanical properties of slag concrete were...
Environmental effects on the bond at the interface between FRP and wood
, Article European Journal of Wood and Wood Products ; Volume 76, Issue 1 , 2018 , Pages 163-174 ; 00183768 (ISSN) ; Toufigh, V ; Mofid, M ; Sharif University of Technology
Springer Verlag
2018
Abstract
The advantages of fiber reinforced polymer (FRP), such as high specific strength, resistance against corrosion and formability, have made it a more acceptable alternative to conventional materials regarding repairing and retrofitting of structures. Although investigations in recent years have proved the concern of civil engineers about the environmental effects on the bond between FRP and concrete or masonry (especially moisture and temperature), only few researches have been reported on FRP-wood interfaces. This research investigated the effect of five different environments on the bond at the interface between FRP and wood. A series of pull-out tests were performed on 375 wood specimens...
Investigation into some parameters affecting pectin gel quality
, Article Scientia Iranica ; Volume 14, Issue 2 , 2007 , Pages 174-179 ; 10263098 (ISSN) ; Alemzadeh, I ; Seifkordi, S. K ; Sharif University of Technology
Sharif University of Technology
2007
Abstract
In this research, gel production from the extracted pectin gel of shahroud sugar beet pulp has been investigated. The pectin extractions were performed in a cold alkaline solution and a hot acid solution, respectively. The effects of different parameters, such as percent of sugar, pectin concentration, calcium content and quantity of peroxidase enzyme, hardness and content of water absorbed by the gel, were studied. Optimum conditions for production of favorable gel, from extracted pectin in this research are, as follows: Percent of sugar (glucose): 15%, peroxidase enzyme content: (pectin unit) 170 pu/g of pectin, pectin concentration (if only gel water uptake is important): 10%, pectin...
Comparison of the corrosion resistance of alkaline- and acid-anodized titanium
, Article Materials Performance ; Volume 54, Issue 1 , 2015 , Pages 51-55 ; 00941492 (ISSN) ; Ghahramani, S ; Afshar, A ; Malekinejad, P ; Sharif University of Technology
National Assoc. of Corrosion Engineers International
2015
Abstract
The process of self-color anodizing of titanium is done in acidic and alkaline solutions, and anodic films of different colors are formed. Results of this work show that the corrosion rate of titanium decreased after the application of an anodizing layer
Enhanced decolorization of Reactive Blue 19 dye from synthetic textile wastewater through UV photolysis in alkaline conditions
, Article Environmental Engineering and Management Journal ; Volume 7, Issue 2 , 2008 , Pages 119-123 ; 15829596 (ISSN) ; Ghaneian, M ; Hashemian, S. J ; Mosavi, G ; Hajizadeh, E ; Sharif University of Technology
Gh. Asachi Technical University of Iasi
2008
Abstract
Laboratory scale experiments were conducted in order to investigate the photolysis of Reactive Blue 19 (RB 19) dye using UV as the irradiation source in alkaline solution. The effects of operating parameters such as, pH, initial dye concentration, UV dosage, hydrogen peroxide and oxygen have been evaluated. The results indicate that the UV photolysis process in alkaline solution is ideal for decolorizing of RB 19 and it can be taken as a starting step to establish the economical feasibility of the method for the decolorization of wastewater from textile industries
Waste ceramic powder-based geopolymer mortars: effect of curing temperature and alkaline solution-to-binder ratio
, Article Construction and Building Materials ; Volume 227 , 2019 ; 09500618 (ISSN) ; Musaeei, H. R ; Mirlohi, F ; Narimani zamanabadi, S ; Ameri, F ; Bahrami, N ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In this study, the optimum curing temperature and alkaline solution-to-binder (S:B) ratio of geopolymer mortars based on waste ceramic powder (WCP) were investigated. For this purpose, mixes with S:B ratios of 0.4–0.7 were prepared and cured at 60, 75, 90, and 105 °C. The density, compressive and flexural strengths were measured at 3, 7, 14, and 28 days. Higher S:B ratios enhanced the flow of the fresh mortar. The optimum mortar was obtained for S:B ratio of 0.6 and curing temperature of 90 °C. The SEM analysis revealed that the optimal mix had a dense matrix with minimum pores. © 2019 Elsevier Ltd
A low cost and highly active non-noble alloy electrocatalyst for hydrazine oxidation based on nickel ternary alloy at the surface of graphite electrode
, Article Journal of Electroanalytical Chemistry ; Volume 763 , 2016 , Pages 134-140 ; 15726657 (ISSN) ; Rostami, T ; Mahjani, M. G ; Gobal, F ; Sharif University of Technology
Elsevier B.V
2016
Abstract
The electrocatalytic oxidation of hydrazine was studied over Ni, Cu, Co and Ni-based ternary alloy on graphite electrodes in alkaline solution. The catalysts were prepared by cycling the graphite electrode in solutions containing Ni, Cu and Co ions at cathodic potentials. The synergistic effects and the catalytic activity of the modified electrodes were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). It was found that, in the presence of hydrazine, the modified Ni-based ternary alloy electrode (G/NiCuCo) exhibited a good catalytic activity for the oxidation of hydrazine at a reduced overpotential and it has a significant high...
Fabrication of durable superhydrophobic surfaces using PDMS and beeswax for drag reduction of internal turbulent flow
, Article Applied Surface Science ; Volume 513 , 2020 ; Liravi, M ; Moosavi, A ; Nouri Borujerdi, A ; Najafkhani, H ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Nowadays, one of the biggest concerns in the world is increasing the CO2 emissions and global warming due to the over-consumption of fossil fuels. In addition, under the intense market competition, the demand for more efficient systems with higher performance and lower energy consumption has escalated. Since the drag force contributes to a considerable percentage of the energy loss and reducing the performance, a large number of studies have been conducted to improve the surface characteristics and, subsequently, declining the drag force. Making the surface superhydrophobic is one of the most effective ways for this purpose. In this work, two different superhydrophobic surfaces using SiO2...
Kinetic interpretation of a negative time constant impedance of glucose electrooxidation
, Article Journal of Physical Chemistry B ; Volume 112, Issue 49 , 2008 , Pages 15933-15940 ; 15206106 (ISSN) ; Jafarian, M ; Forouzandeh, F ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
American Chemical Society
2008
Abstract
Nickel - copper alloy modified glassy carbon electrodes (GC/NiCu) prepared by galvanostatic deposition were used for the electrocatalytic oxidation of glucose in alkaline solutions. The electro-oxidation of glucose in a 1 M NaOH solution at different concentration of glucose was studied by the method of ac-impedance spectroscopy. The impedance behavior show different patterns, capacitive, and inductive loops and negative resistances, at different applied anodic potential. The influence of the electrode potential on the impedance pattern is studied and a quantitative explanation for the impedance behavior of glucose oxidation is put forward by a proposed mathematical model. At potentials...
Investigation of Pb/PbS a positive Schottky junction formed on conductive glass in contact with alkaline solution
, Article Journal of Applied Physics ; Vol. 116, issue. 3 , July , 2014 ; ISSN: 00218979 ; Jafarian, M ; Gobal, F ; Mahjani, M. G ; Miandari, S ; Sharif University of Technology
Abstract
PbS on Pb thin film (Pb/PbS) was deposited on conductive glass (CG) substrate (CG/Pb/PbS) using electrochemical techniques to investigate the Schottky junction in solution. The CG/Pb/PbS electrode was investigated by different techniques based on thermionic emission theory. Electrochemical cell consisted of the CG/Pb/PbS as a working electrode in an alkaline solution showed character of the Schottky junction. Reduction and oxidation of H2O on the CG/Pb/PbS electrode were enhanced under illumination. Water photo splitting is the main process. Study of linear sweep voltammetry at around open circuit potential (OCP) allowed proposing a model based on the Schottky junction which is charged at...
Electrodeposition and electrocatalytic properties of Pt/Ni-Co nanowires for non-enzymatic glucose detection
, Article Journal of Alloys and Compounds ; Volume 554 , 2013 , Pages 169-176 ; 09258388 (ISSN) ; Mahshid, S ; Dolati, A ; Ghorbani, M ; Yang, L ; Luo, S ; Cai, Q ; Sharif University of Technology
2013
Abstract
A nanowire arrays system consisting of an ordered configuration of Pt, Ni and Co was constructed in single-bath solution through pulse electrodeposition. This structure was evaluated as a potential amperometric non-enzymatic sensor to detect glucose in alkaline solution. We observed a strong and fast amperometric response at low applied potential of 0.4 V vs. SCE over linear ranges of 0-0.2 mM and 0.2-8 mM glucose with sensitivities of 1125 and 333 μA mM-1 cm-2, respectively. We also observed a low detection limit for glucose of 1 μM. Correlation of the electronic and geometric modifications with the electrochemical performance characteristics enhanced catalytic activity of the electrode by...
Kinetic studies of glucose electrocatalytic oxidation on GC/Ni electrode
, Article International Journal of Chemical Kinetics ; Volume 44, Issue 11 , 2012 , Pages 712-721 ; 05388066 (ISSN) ; Jafarian, M ; Forouzandeh, F ; Gobal, F ; Sharif University of Technology
2012
Abstract
Nickel-modified glassy carbon electrode (GC/Ni) prepared by galvanostatic deposition was used for the electrocatalytic oxidation of glucose in alkaline solutions where different electrochemical methods were employed. In cyclic voltammetry studies, in the presence of glucose an increase in the peak current of the oxidation of nickel hydroxide is followed by a decrease in the corresponding cathodic current. This suggests that the oxidation of glucose is being catalyzed through mediated electron transfer across the nickel hydroxide layer comprising nickel ions of various valence states. Under the chronoamperometric regime, the reaction followed a Cottrellian behavior and the diffusion...
A comparative study of the electrooxidation of C1 to C3 aliphatic alcohols on Ni modified graphite electrode
, Article Science China Chemistry ; Volume 55, Issue 9 , 2012 , Pages 1819-1824 ; 16747291 (ISSN) ; Mirzapoor, A ; Danaee, I ; Shahnazi, S. A. A ; Gobal, F ; Sharif University of Technology
Abstract
Nickel modified graphite electrodes (G/Ni) prepared by galvanostatic deposition were examined for their redox process and electrocatalytic activities towards the oxidation of methanol, ethanol, 1-propanol and 2-propanol in alkaline solutions. The methods of cyclic voltammetry (CV), chronoamperometry (CA) and impedance spectroscopy (EIS) were employed. In CV studies, the electrochemical response, peak current varied in the order of MeOH > EtOH > 1-PrOH > 2-PrOH. Under the CA regime, a higher catalytic rate constant obtained for methanol oxidation was in agreement with CV measurements. Lower charge transfer resistance was obtained for low carbon alcohols oxidation and significantly higher...
A comparative study of the electrooxidation of ethylene glycol on transition metal electrodes in alkaline solution
, Article Journal of New Materials for Electrochemical Systems ; Volume 15, Issue 4 , 2012 , Pages 255-263 ; 14802422 (ISSN) ; Jafarian, M ; Shahnazi Sangachin, A. A ; Gobal, F ; Sharif University of Technology
2012
Abstract
Electrodes made of group VIII and IB metals were examined for their redox process and electrocatalytic activities towards the oxidation of ethylene glycol in alkaline solutions. The method of cyclic voltammetery (CV) and Open circuit potentials measurement (OCP) was employed. It is found that considerable electrooxidation current are observed for silver and copper but lower anodic overpotential for oxidation is obtained for gold and platinum. Oxide layer produced on the surface of all electrodes in alkaline solution under anodic scan participates in ethylene glycol electrooxidation. Oxidation current observed in the reverse scans for platinum and gold are higher than those observed in...
Polysulfide poisoning of Ag electrocatalyst during L-ascorbate ion electro-oxidation in alkaline solution
, Article Cuihua Xuebao/Chinese Journal of Catalysis ; Volume 33, Issue 2 , 2012 , Pages 267-274 ; 02539837 (ISSN) ; Majari Kasmaee, L ; Sharif University of Technology
Abstract
L-Ascorbate anion electro-oxidation on a silver electrode in hydroxide solution in the absence and presence of sodium polysulfide of concentrations from 1 × 10 -5 to 4.5 × 10 -4 mol/L was studied using cyclic voltammetry and electrochemical impedance spectroscopy. Both hydroxide and polysulfide ions inhibited L-ascorbate ion oxidation, with the poisoning effect of polysulfide ion being more pronounced in the potential range of -0.3 to -0.2 V/SCE. The time constants for L-ascorbate ion oxidation in the absence and presence of polysulfide were, 10 -3 to 1 × 10 -2 s and 1 × 10 -4 to 1 × 10 -2 s, respectively depending on the potential used for the impedance analysis. Based on the cyclic...
A comparative investigation of the electrocatalytic oxidation of methanol on poly-NiTCPP and poly-TCPP/Ni modified glassy carbon electrodes
, Article Journal of Electroanalytical Chemistry ; Volume 663, Issue 1 , December , 2011 , Pages 14-23 ; 15726657 (ISSN) ; Haghighatbin, M. A ; Gobal, F ; Mahjani, M. G ; Rayati, S ; Sharif University of Technology
2011
Abstract
Electro-oxidation of methanol in alkaline solution at a glassy carbon electrode electrochemically modified by a conductive polymeric meso-tetra(4-carboxyphenyl)porphyrinato nickel(II), abbreviated as poly-NiTCPP and also meso-tetra(4-carboxyphenyl)porphyrin with incorporated nickel(II) cations, abbreviated as, poly-TCPP/Ni, were investigated and compared. Both films were prepared by oxidative electro-polymerization of complexes by repetitive cyclic voltammetry (RCV) in 0.1 M NaOH aqueous solution. The electrochemical properties and behaviors and also kinetic values of both films have been characterized and compared using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical...
Template-based electrodeposition of Pt/Ni nanowires and its catalytic activity towards glucose oxidation
, Article Electrochimica Acta ; Volume 58, Issue 1 , 2011 , Pages 551-555 ; 00134686 (ISSN) ; Mahshid, S ; Dolati, A ; Ghorbani, M ; Yang, L ; Luo, S ; Cai, Q ; Sharif University of Technology
2011
Abstract
An electro-catalysis non-enzymatic electrode is proposed based on alloyed Pt/Ni nanowire arrays (NWAs) for the detection of glucose. The Pt/Ni NWAs were prepared by pulse electrodeposition of Pt and Ni within a nano-pore polycarbonate (PC) membrane followed by a chemical etching of the membrane. The electrode structure is characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The resulting Pt/Ni NWAs electrode shows high electrocatalytic activities towards the oxidation of glucose in alkaline solution. Consequently, a sensitive amperometric detection of glucose is achieved under 0.45 V vs. SCE with a low detection limit of 1.5 μM within a wide linear...