Search for: sulfur
0.008 seconds
Total 260 records

    Desulfurization of Tabas coal with microwave irradiation/peroxyacetic acid washing at 25, 55 and 85 °C

    , Article Fuel ; Volume 83, Issue 7-8 , 2004 , Pages 943-949 ; 00162361 (ISSN) Jorjani, E ; Rezai, B ; Vossoughi, M ; Osanloo, M ; Sharif University of Technology
    Tabas coal sample from Iran was desulfurized with combination of microwave irradiation and peroxyacetic acid washing in a batch reactor. The effect of irradiation time and power, peroxyacetic acid reaction time and temperature and particle size on reduction of sulfur was investigated. For microwaved/acid washed samples, depending on desulfurization conditions, the reduction in pyritic, organic and total sulfur ranged from 26 to 91, 2.6 to 38.4 and 17 to 65%, respectively. Microwave irradiation had positive effect on desulfurization with peroxyacetic acid. For <300 μm size fraction, after irradiation, the reduction enhanced from 49.9 to 86.6% in pyritic sulfur, 23.8 to 35% in organic sulfur... 

    Computational modeling of intraocular gas dynamics

    , Article Physical Biology ; Volume 12, Issue 6 , 2015 ; 14783967 (ISSN) Noohi, P ; Abdekhodaie, M. J ; Cheng, Y. L ; Sharif University of Technology
    Institute of Physics Publishing  2015
    The purpose of this study was to develop a computational model to simulate the dynamics of intraocular gas behavior in pneumatic retinopexy (PR) procedure. The presented model predicted intraocular gas volume at any time and determined the tolerance angle within which a patient can maneuver and still gas completely covers the tear(s). Computational fluid dynamics calculations were conducted to describe PR procedure. The geometrical model was constructed based on the rabbit and human eye dimensions. SF6 in the form of pure and diluted with air was considered as the injected gas. The presented results indicated that the composition of the injected gas affected the gas absorption rate and gas... 

    The effect of viscosity, applied frequency and driven pressure on the laser induced bubble luminescence in water-sulfuric acid mixtures

    , Article Physics Letters, Section A: General, Atomic and Solid State Physics ; Volume 380, Issues 27–28 , June , 2016 , Pages 2219–2226 ; 03759601 (ISSN) Sadighi Bonabi, R ; Alijan Farzad Lahiji, F ; Razeghi, F ; Sharif University of Technology
    Elsevier  2016
    Production and oscillation of sonoluminescence bubbles by laser pulse in the presence of acoustic field in water and different concentrations of sulfuric acid are investigated. In the presence of acoustic field, the laser causes variable speed of sound, surface tension and density; and the host liquid acts as a compressible one and strongly affects the bubble's dynamics equations. The effect of various concentrations of sulfuric acid as a host liquid on the oscillation of bubble radius, bubble wall velocity and bubble interior temperature is studied. Furthermore, the effect of applied frequency on LI-SCBL in the presence of the acoustic field is investigated and an optimum sound wave... 

    Improving the performance of lithium-sulfur batteries using sulfur-(TiO2/SiO2) yolk-shell nanostructure

    , Article Journal of Nanostructures ; Volume 10, Issue 1 , 2020 , Pages 76-82 Safaei, P ; Sepahvand, S ; Hossieni, F ; Ghasemi, S ; Sanaee, Z ; Sharif University of Technology
    University of Kashan  2020
    Lithium-Sulfur (Li-S) batteries are considered as one of the promising candidates for next-generation Li batteries in near future. Although, these batteries are suffering from certain drawbacks such as rapid capacity fading during the charge and discharge process due to the dissolution of polysulfides. In this paper, Sulfur/metal oxide (TiO2 and SiO2) yolk-shell structures have been successfully synthesized and utilized to overcome this problem and improve the electrochemical performance of sulfur cahtode material. Prepared materials have been characterized using Scanning Electron Microscopy(SEM), Transmission Electron Microscopy(TEM) and X-ray diffraction (XRD) techniques. The results show... 

    Oxidative desulfurization of Non-hydrotreated kerosene using hydrogen peroxide and acetic acid

    , Article Chinese Journal of Chemical Engineering ; Volume 17, Issue 5 , 2009 , Pages 869-874 ; 10049541 (ISSN) Molaei Dehkordi, A ; Sobati, M. A ; Nazem, M. A ; Sharif University of Technology
    The oxidative desulfurization of a real refinery feedstock (i.e., non-hydrotreated kerosene with total sulfur mass content of 0.16%) with a mixture of hydrogen peroxide and acetic acid was studied. The influences of various operating parameters including reaction temperature (T), acid to sulfur molar ratio (nacid/nS), and oxidant to sulfur molar ratio (nO/nS) on the sulfur removal of kerosene were investigated. The results revealed that an increase in the reaction temperature (T) and nacid/nS enhances the sulfur removal. Moreover, there is an optimum nO/nS related to the reaction temperature and the best sulfur removal could be obtained at nO/nS8 and 23 for the reaction temperatures of 25... 

    A survey on exergy, energy and environmental analysis of sulfur recovery unit in case of five intensified configurations

    , Article Chemical Papers ; Volume 73, Issue 6 , 2019 , Pages 1529-1539 ; 03666352 (ISSN) Rostami, A ; Tavan, Y ; Sharif University of Technology
    Springer International Publishing  2019
    In this study, a combination of energy and exergy analysis is applied for the industrial sulfur recovery unit (SRU) in commercial simulation software. The data of energy and exergy are obtained from the simulator and Excel (for physical and chemical exergy), respectively. In doing so, five intensified SRU configurations namely: (1) hot gas bypass (2) acid gas bypass (3) inlet stream preheating (4) acid gas enrichment and (5) oxygen (air) enrichment are compared in terms of energy production, reaction furnace temperature, sulfur recovery and pollutant emission into environment. Then, irreversibility in these five arrangements is compared and all the proposed methods show higher useful exergy... 

    Silica sulfuric acid as a reusable catalyst for efficient and simple silylation of hydroxyl groups using hexamethyldisilazane (HMDS)

    , Article Phosphorus, Sulfur and Silicon and the Related Elements ; Volume 182, Issue 7 , 2007 , Pages 1645-1651 ; 10426507 (ISSN) Ghafuri, H ; Eftekhari-Sis, B ; Hashemi, M. M ; Sharif University of Technology
    At room temperature, alcohols and phenols are efficiently protected with hexamethyldisilazane (HMDS) in the presence of silica sulfuric acid in good to excellent yields. The catalyst can be recycled for subsequent reactions without any appreciable loss of efficiency. Copyright © Taylor and Francis Group, LLC  

    Biodesulfurization of dibenzothiophene by a newly isolated thermophilic bacteria strain

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 25, Issue 3 , 2006 , Pages 65-72 ; 10219986 (ISSN) Hosseini, S. A ; Yaghmaei, S ; Mousavi, S.M ; Jadidi, A.R ; Sharif University of Technology
    Microbiological analyses of soil chronically exposed to petroleum complex compounds of some oil springs in south of Iran resulted in isolation and purification of a new native thermophilic strain which is capable to desulfurize petroleum sulfur compounds by 4-S mechanism. Dibenzothiophene (DBT) was selected as a complex sulfiir compound model and many experiments were done to identify the metabolic pathway. The results of these experiments show that DBT is ultimately converted to 2-hydroxybiphenyl (2-HBP) and sulfite. This is a special metabolic pathway in that there is no effect on the carbon skeleton of organic compounds and would be ideal for desulfurization to upgrade the petroleum... 

    Atmospheric corrosion evaluation of silver coating using simulating technique test

    , Article European Corrosion Conference: Long Term Prediction and Modelling of Corrosion, EUROCORR 2004, Nice, 12 September 2004 through 16 September 2004 ; 2004 Nasirpouri, F ; Afshar, A ; Sharif University of Technology
    A standard simulating technique test was investigated to assess the atmospheric corrosion behavior of silver coating. The rates of formation of corrosion products were measured in the simulating atmospheres of 100% humidity containing SO 2,H 2S and a complex atmosphere consist of SO 2,H 2S and NO 2 gases ,based on the mass increase method. The concentrations of corrosive gases were chosen according to real world conditions. XRD, SEM and EDS were used to examine the morphology and to determine the composition of the corrosion products under different experimental conditions. Results revealed the formation of Ag 2SO 4 and Ag 2S on the silver coating surfaces in the SO 2 and H 2S containing... 

    Mild and heterogeneous oxidation of urazoles to their corresponding triazolinediones via in situ generation Cl+ using silica sulfuric acid/KClO3 or silica chloride/oxone system

    , Article Catalysis Communications ; Volume 8, Issue 3 , 2007 , Pages 256-260 ; 15667367 (ISSN) Zolfigol, M. A ; Bagherzadeh, M ; Mallakpour, S ; Chehardoli, G ; Kolvari, E ; Ghorbani Choghamarani, A ; Koukabi, N ; Sharif University of Technology
    A combination of silica sulfuric acid and potassium chlorate or oxone® and silica chloride in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidation of urazoles and bis-urazoles to their corresponding triazolinediones under mild and heterogeneous conditions with moderate to excellent yields. © 2006 Elsevier B.V. All rights reserved  

    Study of a newly isolated thermophilic bacterium capable of Kuhemond heavy crude oil and dibenzothiophene biodesulfurization following 4S pathway at 60°C

    , Article Journal of Chemical Technology and Biotechnology ; Volume 83, Issue 12 , June , 2008 , Pages 1689-1693 ; 02682575 (ISSN) Torkamani, S ; Shayegan, J ; Yaghmaei, S ; Alemzadeh, I ; Sharif University of Technology
    Background: To meet stringent emission standards stipulated by regulatory agencies, the oil industry is required to bring down the sulfur content in fuels. As some compounds cannot be desulfurized by existing desulfurizing processes (such as hydrodesulfurization, HDS) biodesulfurization has become an interesting topic for researchers. Most of the isolated biodesulfurizing microorganisms are capable of desulfurization of refined products whose predominant sulfur species are dibenzothiophenes so biocatalyst development is still needed to desulfurize the spectrum of sulfur-bearing compounds present in whole crude. Results: The first desulfurizing bacterium active at 60 °C has been isolated,... 

    Electrochemical oxidative desulfurization for high sulfur content crude gas-oil

    , Article Separation and Purification Technology ; Volume 248 , 2020 Tavan, Y ; Shahrokhi, M ; Farhadi, F ; Sharif University of Technology
    Elsevier B.V  2020
    Presence of sulfur components in liquid fuels should be controlled due to environmental issues and process considerations. In order to decrease the level of sulfurous compounds in crude gas-oil with 5750 ppmw sulfur, electrochemical oxidative desulfurization has been investigated over electrodes of copper and stainless steel because of their easy operation and mild process conditions. In this research, the effects of stirring rate, temperature, applied potential, sodium hydroxide addition as electrolyte media and water volume have been examined on the sulfur removal efficiency. The results show that electrical conductivity of gas-oil sharply increases with addition of electrolyte up to 613... 

    Novel microfluidic graphene oxide–protein amperometric biosensor for detecting sulfur compounds

    , Article Biotechnology and Applied Biochemistry ; Volume 66, Issue 3 , 2019 , Pages 353-360 ; 08854513 (ISSN) Ghaemi, A ; Abdi, K ; Javadi, S ; Shehneh, M. Z ; Yazdian, F ; Omidi, M ; Rashedi, H ; Haghiralsadat, B. F ; Asayeshnaeini, O ; Sharif University of Technology
    Wiley-Blackwell Publishing Ltd  2019
    Sulfur compounds are essential for many industries and organisms; however, they cause serious respiratory problems in human beings. Therefore, determination of sulfur concentration is of paramount importance. The research approach in the field of detecting contaminants has led to smaller systems that provide faster and more effective ways for diagnosis purposes. In this study, a novel portable amperometric graphene oxide–protein biosensor platform is investigated. The main characteristic of this structure is the implementation of a microfluidic configuration. With albumin metalloprotein as the biorecognition element, graphene oxide was synthesized and characterized by transmission electron... 

    Reducing Sulfur Dioxide Using NANO-Structured Materials

    , M.Sc. Thesis Sharif University of Technology Fasahat, Hossein (Author) ; Safekordi, Ali Akbar (Supervisor)
    In this research, absorption and oxidation catalytic scenarios were examined using previous studies in the field of SO2 removal. Nanostructures zeolite 13X, 5A zeolite, gamma alumina and activated carbon were purchased, then structure, function and adsorption isotherm of each adsorbent were evaluated in 5 concentrations of 250, 500, 750, 1000 and 1250 ppm of contaminants. Final results showed that zeolite 13X compared to other Nano-adsorbents has higher ability to SO2 absorption, and thus the final tests such as temperature and pressure evaluation were performed on the selected sorbent. To further evaluation, the absorbent curves based on two models of BDST (Bed depth service time) and... 

    , M.Sc. Thesis Sharif University of Technology Ebrahimi, Narjes Khatoon (Author) ; Samadfam, Mohammad (Supervisor) ; Mallah, Mohammad Hassan (Supervisor) ; Safdari, Jaber (Supervisor)
    In many uranium mines such as gachin-bandarabbas, use sulfuric acid for leaching operation on ore. This leach liquor, containing uranium, is extracted by organic solvent, such as D2EHPA (dapex process ).althogh this process have being used for many years, there is a vacancy for detailed thermodynamical studying on uranium extraction of uranium from leach liquor. To have a thermodynamical model, we need information on equilibrium concentration of all component that may have effect on uranium extraction in addition we need concentration of solvent , pH, phase ratio and activity coefficient.such a model must have the ability to predict the equilibrium concentration in alloperation condition.... 

    Ambient temperature effect on single-bubble sonoluminescence in different concentrations of sulfuric acid solutions

    , Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 85, Issue 1 , January , 2012 ; 15393755 (ISSN) Imani, Kh ; Bemani, F ; Silatani, M ; Sadighi Bonabi, R ; Sharif University of Technology
    The effect of ambient temperature on the parameters of the single-bubble sonoluminescence in sulfuric acid (SA) diluted in water is studied. Using a hydrochemical model, three dominant instabilities of shape, Bjerknes, and diffusion are considered. The phase diagrams of the bubble in the (R 0 - P a) space are presented, and the parametric dependence of the light intensity is discussed. In contrast to water, the calculated thermal-bremsstrahlung mechanism of light emission at the fixed degassing condition of high SA concentrations shows that, with increasing the temperature of aqueous SA solutions, the light intensity increases. However, at diluted SA solutions similar to water, the light... 

    Liquid-liquid extraction of oxidized sulfur-containing compounds of non-hydrotreated kerosene

    , Article Fuel Processing Technology ; Volume 91, Issue 11 , November , 2010 , Pages 1386-1394 ; 03783820 (ISSN) Sobati, M. A ; Molaei Dehkordi, A ; Shahrokhi, M ; Sharif University of Technology
    An experimental study was conducted on the desulfurization of non-hydrotreated kerosene with oxidation followed by liquid-liquid extraction. Various types of solvents including acetonitrile, methanol, and ethanol have been examined in the extraction of oxidized sulfur-containing compounds of kerosene. The performance of these solvents has been carefully examined and compared. It was found that their performance follows the order: acetonitrile > methanol > ethanol. The effects of number of extraction stages and solvent to kerosene ratio on the desulfurization and recovery of kerosene have been investigated. The experimental results show that for all three solvents, solvent/kerosene ratio and... 

    The separation of cadmium from zinc with a synergistic mixture of nonylsalicylic acid and triisobutylphosphine sulphide

    , Article Hydrometallurgy ; Volume 78, Issue 1-2 SPEC. ISS , 2005 , Pages 129-136 ; 0304386X (ISSN) Moradkhani, D ; Urbani, M ; Cheng, C. Y ; Askari, M ; Bastani, D ; Sharif University of Technology
    Metal pH50 and ΔpH50 values were determined and compared for a number of organic systems to select a synergistic system for the separation of Cd from Zn. The largest ΔpH50(Zn-Cd) value was obtained with HRJ-4277 (nonylsalicylic acid)/Cyanex 471X (triisobutyl phosphine sulphide or TIBPS) system and reached 1.53 pH units, indicating excellent separation of Cd from Zn with this system. Shellsol 2046 was chosen as the diluent of the system due to its larger ΔpH50(Zn-Cd) and excellent phase separation compared with other diluents. Distribution isotherms and subsequent McCabe-Thiele diagrams indicate that 99% Cd could be extracted in two stages at pH 3.80 and A / O ratio of 1.5 : 1. The extraction... 

    The Corrosion Behavior of Sulfur Concrete in Persian Gulf Sea Water

    , M.Sc. Thesis Sharif University of Technology Haghipour, Amir (Author) ; Dolati, Abolghasem (Supervisor)
    In this project sulfur concretes were prepared. The optimum of casting temperature, weight percent of sulfur cement and weight percent of filler were analyzed, so that better corrosion resistance could be found. It is observed, the optimum sulfur is 15% for sulfur concrete samples with 21% sulfur cement; the optimum filler is 10-15% with 18% sulfur cement and finally the optimum filler is 10% for concrete samples with 15% sulfur cement. The casting temperature for concrete with 15-21% sulfur cement is in the interval of 127-150°C could be achieved. By applying the relation between the optimum filler percent and the content of sulfur cement and choosing a suitable temperature for casting... 

    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...