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Pressure leaching of chalcopyrite concentrate with oxygen and kinetic study on the process in sulfuric acid solution
, Article Transactions of the Indian Institute of Metals ; Volume 73, Issue 4 , 6 March , 2020 , Pages 975-987 ; Rasouli, S ; Yoozbashizadeh, H ; Sharif University of Technology
Springer
2020
Abstract
In this research work, the pressure leaching of chalcopyrite concentrate with oxygen was studied. Experiments were carried out under conditions of the solid–liquid ratio of 0.1, agitation speed of 750 rpm, and sulfuric acid concentration of 2 M in a stainless-steel autoclave system under 0.6 to 1 MPa oxygen gas. Central composite design was used to design experiments, and three factors of temperature, time, and oxygen pressure were selected as the design variables. A linear model for %Cu and a quadratic model for %Fe were proposed by Minitab Software. The results showed that temperature is the most effective factor in chalcopyrite leaching. Under optimal conditions, 93.08% of copper with the...
DFT study on Thiotepa and Tepa interactions with their DNA receptor
, Article Structural Chemistry ; Volume 24, Issue 1 , February , 2013 , Pages 1-11 ; 10400400 (ISSN) ; Fattahi, A ; Sharif University of Technology
2013
Abstract
Thiotepa (N,N′,N″-triethylenethiophosphoramide) and its major metabolite (Tepa) as trifunctional alkylating agents has recently been used in cancer therapy. In vivo and vitro studies show the possible pathways of alkylation of DNA by Thiotepa and Tepa. Two pathways are suggested, but the main pathway of mechanism remains unclear. In pathway 1, forming cross-links with DNA molecules can be carried out via two different mechanisms. In first mechanism, these agents undergo the ring opening reaction which is initiated by protonating aziridine, which then becomes the main target of nucleophilic attack by the N7-Guanine of DNA. The second probable mechanism is ring opening of aziridyl group by...
On the assessment of photocatalytic activity and charge carrier mechanism of TiO2@SnO2 core-shell nanoparticles for water decontamination
, Article Journal of Photochemistry and Photobiology A: Chemistry ; Volume 338 , 2017 , Pages 171-177 ; 10106030 (ISSN) ; Mohammadi, M. R ; Ghorbani, M ; Sharif University of Technology
Elsevier B.V
2017
Abstract
We synthesize TiO2@SnO2 core-shell nanoparticles (NPs) by a facile two-step aqueous sol-gel method and their photocatalytic activity is compared with the pure TiO2 and SnO2 NPs for degradation of methylene blue under UV irradiation. The chemical property, crystal structure and morphology of the synthesized samples are studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM) and transmission electron microscope (TEM) techniques. The mechanisms of electron–hole recombination and separation of charge carriers are studied by photoluminescence (PL) and diffuse reflectance spectroscopy (DRS). Furthermore, the kinetics...
Renewable hydrogen production by ethylene glycol steam reforming over Al2O3 supported Ni-Pt bimetallic nano-catalysts
, Article Renewable Energy ; Volume 128 , 2018 , Pages 188-199 ; 09601481 (ISSN) ; Khorasheh, F ; Sharif University of Technology
Abstract
The steam reforming of ethylene glycol, a simple model compound for biomass-derived liquids, is considered to be an environmentally green process for producing renewable hydrogen. Both Pt and Ni species are known for their catalytic activity under steam reforming reaction conditions. In this investigation, alumina supported Ni-Pt bimetallic catalysts (X wt% Ni-Y wt% Pt/Al2O3 named XNi-YPt) were employed for steam reforming of ethylene glycol. The prepared catalysts were characterized by XRD, BET, H2-TPR, H₂-Chemisorption, and TEM. It was observed that Ni/Pt ratio strongly affected the redox behavior, BET surface area, and particle size of the samples that in turn affected their catalytic...
Study of Biological Extraction Kinetics of Heavy Metals from Spent Catalyst by Thermophilic Bacteria
, M.Sc. Thesis Sharif University of Technology ; Yaghmaei, Soheyla (Supervisor) ; Mousavi, Mohammad (Supervisor)
Abstract
Every year, an enormous amount of catalysts are consumed in oil refineries during refining processes. After some regeneration cycles in order to recover their activity, they are not anymore effective and must be disposed. These spent catalysts are regarded as dangerous solid wastes as they significantly include some contaminations like vanadium, nickel, arsenic, sodium. From another point of view, the metals present in spent catalysts are highly valuable and are used extensively in steel industry and manufacture of special alloys. So, it sounds profitable to extract and recover these metals from such a cheap source instead of minerals and ores. Basically, there are two main processes, hydro-...
Kinetic of Partial Reduction of Hematite to Magnetite
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
This research has studied the kinetic and mechanism of partial reduction of hematite to magnetite via carbon monoxide gas. In addition, temperature and partial pressure of CO gas as two main parameters which influence the rate of the reduction process has been studied. In order to investigate the change in mass during the reaction, thermogravimetric analysis (TGA) has been applied and in order to evaluate the effect of the temperature and partial pressure of CO on the rate of the reduction, three different temperatures and two different ratios of CO/CO2 has been experimented. Three isothermal analysis in 390°C, 440°C, and 490°C in pure CO atmosphere and two isothermal analysis in 550°C with...
Simulation of Hydrodesulfurization Plant
, M.Sc. Thesis Sharif University of Technology ; Fahadi, Fathollah (Supervisor)
Abstract
Sulfur components are one of the most important impurities in various petroleum fractions that cause many problems in refining and consumption. In this thesis, hydrodesulfurization process, which has an economical and environmental especial position in petroleum and other related industries, has been discussed. In hydrodesulfurization process, under specific operation condition, sulfur components are converted catalytically to the H2S in a fixed bed reactor. In this study dibenzothiophene, which is one of the most strength and complex sulfur components, is considered as the base component. A Langmuir-Hinshelwood kinetic equation is used to describe the reaction by using the commercial...
Effect of Kinetic and Hydrodynamic on Asphaltene Deposition in Porous Media
, Ph.D. Dissertation Sharif University of Technology ; Rashtchian, Davoud (Supervisor) ; Jamialahamdi, Mohammad (Supervisor) ; Tohidi, Bahman (Supervisor)
Abstract
Asphaltene are the heaviest components if some crude oil which are in thermodynamic equilibrium. Any change in the equilibrium condition including change in temperature, pressure or composition may render asphaltene to come out of solution and precipitate. Asphaltene precipitation and deposition is one of the main problems in some of the oil fields. Precipitated asphaltene may deposit in the reservoir, near wellbore, wellstring, transport pipeline and surface facilities. In porous media, the deposited asphaltene over the surface and/or across pore throat can severely reduce the effective permeability and results in decreasing of the oil production. Also, the deposited asphaltene results in...
Thermodynamic and Kinetic Study for Production of Micro and Nano Poly(Ethylene Terephthalate) Particles With Supercritical System
, M.Sc. Thesis Sharif University of Technology ; Goodarznia, Iraj (Supervisor)
Abstract
It is well known that poly(ethylene terephthalate) (PET) is a high melting compound which has exceptional value as a fiber and film-making material, and which currently dominates the whole field of linear polyester substances. However, the high viscosity and limited solubility in liquid solvents restrict its processing to powders and hence the range of applications of such a polymer. Traditionally, crushing, mechanical grinding, ball milling and precipitation from solution are methods for producing powders. The first three ones inevitably change the property of materials. The last one is carried out on the basis of the application of an anti-solvent to decrease the solubility of a...
Synthesis of NiO Nano-Powder by TSSC Process and NiO Nano-Layers synthesis by TSCD Process and Kinetics Modeling of Nickel Oxide Nano-Layer Growth by Diffuse-Interface Model
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhad, Khatiboleslam (Supervisor)
Abstract
Nickel oxide is used in the manufacture of ceramic, magnetic materials, battery cathodes, electrochromic films, heterogeneous catalytic materials and gas sensors. NiO nano-powder can be produced with many different methods. The synthesis of NiO nanopowder has been carried out via solochemical processing from an aqueous solution of a Ni containing complex in this research. Another name for this method is two-stage solochemical (TSSC) method. This is the newest economic method for synthesis of NiO nanopowder. NiCl2 anhydrous and NH3-H2O used as the raw materials and H2O used as solvent. The results obtained from XRD and TEM show that the nanoparticles have cubic crystal structure and the mean...
Evaluation of Kinetics of Nickel Oxide Reduction by Carbon Dissolved in Molten Iron
,
M.Sc. Thesis
Sharif University of Technology
;
Davami, Parviz
(Supervisor)
;
Halali, Mohammad
(Supervisor)
Abstract
In this study, the recovery mechanism of nickel oxide by carbon dissolved in molten iron with the study of reaction kinetics were investigated. Nickel oxide pellets into molten iron containing graphite were added in the neutral atmosphere and the release of CO gas as a function of reaction time was measured until the end. The volume of gas produced at different times shows the number of moles of Ni metal was revived. Reaction by a) the following decomposition reaction under 1475 °C ; and b) carbon diffusion rate at temperatures over ° C1475 is controlled. The main reaction mechanism in order to a) decomposition of NiO; b) penetration of oxygen atoms in the melt, and c) reaction between...
Kinetics Modeling of Platinum Leaching from Reforming Spent Catalysts by iodine/iodide Solution
, M.Sc. Thesis Sharif University of Technology ; Baghalha, Morteza (Supervisor)
Abstract
Platinum is one of the most used catalysts in refining and petrochemical industries. Also, Platinum uses in other industries like automobile catalytic convertor. As respect to importance of Platinum in these industries, growth of its consumption in recent decades and its very high price, recovery of Platinum is essential. Hence, many of various methods including hydro-metallurgy are applied. In despite of these wide spreading experimental investigations, due to low information about the reactions and the nature of reaction products, a few investigations were done on kinetics of Platinum recovery. A new method that used iodine solution to extract Platinum from spent reforming catalysts was...
DFT Study on Mechanism and Kinetic of Thiotepa and Tepa Interaction with its DNA Receptor
,
M.Sc. Thesis
Sharif University of Technology
;
Fattahi, Alireza
(Supervisor)
Abstract
N, N′, N″-triethylenethiophosphoramide (Thiotepa) and its oxo analogue (Tepa) as the major metabolite are trifunctional alkylating agents with a broad spectrum of antitumor activity. In vivo and vitro studies show alkylation of DNA by Thiotepa and Tepa can follow two pathways, but it remains unclear which pathway represents the precise mechanism of action. In pathway 1, these agents are capable of forming cross-links with DNA molecules which can be carried out via two different mechanisms. In the first mechanism, the ring opening reaction is initiated by protonating the aziridine, which then becomes the primary target of nucleophilic attack by the N7-Guanine of DNA. The second one is the...
, M.Sc. Thesis Sharif University of Technology ; Yoozbashizadeh, Hossein (Supervisor)
Abstract
High advantages of hydrometallurgy have led to its recent development in metal extraction. Many investigations are being carried out on applying hydrometallurgy processes on copper extraction. In this study, the chloride leaching of chalcopyrite in a concentrated sodium chloride solution (4M) –which is a novel process–, using CuCl2 as leachant is investigated. Main effects and interactions of temperature (50–90°C), time (2–6 hr), CuCl2 concentration (0.1–0.5M), pulp density and HCl concentration (0.1–1M) at constant stirring rate (600 rpm) on leaching is studied using 2k factorial design and applying Design–Expert 7.0.0 software. While the effect of pulp density is almost negligible,...
Preparation, Characterization and Catalytic Application of Some Polyoxometalates for Esterification Reaction
, M.Sc. Thesis Sharif University of Technology ; Rahman Setayesh, Shahrbanoo (Supervisor)
Abstract
Catalytic esterification of acetic acid with 1-hexanol was investigated over polyoxometalates. H3PW12O40 and H3PMo6W6O40 polyoxometalates with keggin structures were synthesized. Catalytic activity and recyclability of them were improved by loading on the γ-Al2O3 with impregnation method and Cs, K and NH4 salts preparing.Catalysts were characterized by XRD, SEM, FT-IR, BET, DRS and NMR techniques. According to XRD's results, catalysts have ace-centered cubic crystal systems. Loading on supports and preparing the salts do not destroy the structures of polyoxometalates. SEM images show the uniformity of catalysts' surface and catalysts' fixing on the support. It was seen that the keggin...
An Investigation into the Effect of Prestrain Temperature on the Static
Recrystallization of low Carbon Steel
,
M.Sc. Thesis
Sharif University of Technology
;
karimi Taheri, Ali
(Supervisor)
Abstract
In this project the effect of rolling temperature on mechanical properties and microstructure evolution of a low carbon steel was studied. The steel was rolled up to a nominal strain of 67% at three different temperatures consisted of room, blue brittleness, and subzero temperature. Micreohardnessand tensile tests were used to characterize the recrystallization kinetics. Optical and scanning electron microscopic examinations were carried out to evaluate the mechanical, grain size, and the kinetics of static recrystallization by the Avrami equation. The results indicated that the volume fraction of static recrystallization increases with the increase in annealing period. The Avrami exponent...
Bioleaching of Metal from Electronic Wastes Using Acidithiobacillus Ferrooxidans
, M.Sc. Thesis Sharif University of Technology ; Yaghmaei, Soheila (Supervisor)
Abstract
The recycling of the secondary resources for the extraction of their metallic contents is undoubtedly environmentally friendly and can be economic. One of the most important secondary resources is the electronic wastes (E-wastes) which has been widely produced as the discarded electrical/electronic devices. The usual physical/chemical treatments of E-wastes not only result in an increase in human health risks and environmental pollution but also lead to the missing of their valuable metallic contents. An alternative method for the recycling of E-wastes is bioleaching which has recently attracted more attention. The advantages of this process are low energy consumption and environment...
Synthesis and Characterization of Structured Nanocatalysts and Their Applications in Kinetics Study of Oxidation-reduction Reactions
, Ph.D. Dissertation Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor) ; Rahman Setayesh, Shahbanoo (Co-Advisor)
Abstract
In present study, various cocatalysts were used to improve catalytic properties of metal oxides and oxy-acids. Ag3VO4/Ag3PO4/Ag and Cu2O/MoS2/rGO photocatalysts were synthesized. The photocatalytic activities of the prepared nanocomposites were evaluated by the photodegradation of dye in the heterogenous systems as a series of advanced oxidation reactions. The results revealed that heterojunction between two semiconductors may prevent fast electron-hole pair recombination and then improve efficiency and rate of dye photodegradation. Mechanism and kinetics of dye degradation were studied in the presence of new photocatalysts by using of different scavengers. In the other works, Pt-NiO/G and...
Theoretical and Experimental Study of the Influence of Chemical Environments and Investigation of their Effects on the Kinetics of Redox Reactions using Metal and Metal Oxide Nanocatalyst
, Ph.D. Dissertation Sharif University of Technology ; Gholami, Mohammad Reza (Supervisor)
Abstract
Bimetallic nanoparticles with unique structure, synergistic effect between two metals, and the tunable physical/chemical properties have been used for catalysis. Various methods exist for the staibility, and improvement of the catalytic performance of nanoparticles. In this thesis, different co-catalysts were applied to increase tha staibility, and activity of nanoparticles and metal oxides. In this way, Ni-based bimetallic nanoparticles including CuNi, CoNi, and AgNi, and AgPt with different concentrations were synthesized on the cerium oxide nanorods derived from cerium metal-organic frameworks and magnetic graphene oxide nanosheets, respectively and characterized. The catalytic...
Direct Reduction of Magnetite with Thermal Coal in Concentric Cylindrical Arrangement
, Ph.D. Dissertation Sharif University of Technology ; Askari, Masoud (Supervisor)
Abstract
Direct Reduction of magnetite concentrate with thermal coal in concentric cylindrical arrangement has been investigated. At first, thermal behavior and physical and chemical properties of 3 type of coals from different coal mines of Iran in a thermal treatment similar to pre heating section of tunnel kiln direct reduction of Iron were investigated.Study of changes in reactivity and calorific values of coal in addition to providing a fundamental understanding of coal performance in the thermal process of reduction set a base for investigation of recycling of unburnt coal in the reduction process. Thermogravimetric data for coal devolatilization in three heating rates yielded an activation...