Sharif Digital Repository

This study presents the experimental investigation, the effect of cement based chemical materials (Portland cement as a repair material No1. and 2 other cement base chemical materials) to upgrade the structural behavior of reinforced concrete slabs built with low quality (porous) concrete. The main issues focused in this investigation are: (i) the effect of repair on the flexural behavior of RC slabs in terms of ultimate capacity and ultimate mid-span deflection and ductility of specimens, (ii) the influence of repair materials on failure modes and (iii) evaluating the efficiency of different materials on decreasing the porosity of concrete by ultrasonic test. Because materials used in this... 

In this research, for the first time, the emulsion liquid membrane method was used in a pulsed sieve plate column to separate uranium from uranyl nitrate solution. The L-shaped pulse extraction column was implemented on a semi-industrial scale at the Atomic Energy Organization. For the design and scale-up of these columns, it is necessary to measure hydrodynamic parameters and investigate the effects of operating parameters on them. The hydrodynamic parameters measured in this study include dispersed phase holdup and slip velocity under two conditions: without mass transfer and with mass transfer. Despite efforts, the operating conditions in the L-shaped column did not allow for the... 

Centrifuge is a method in which great gravitational-like forces are used. Gravitational forces which cause molecules to move and are relevant to molecular weight; can cause isotope separation. The separation of light isotope from heavy one is done with a centrifugal field which produces a pressure gradient for the gas mixture. Pressure gradient is different for each of the isotopes due to the dependence of pressure gradient to the mass of the materials. But the separation in this way is very limited. The capacity of separation can be brought up by producing an additional axial flow in the rotor. This rotational flow can be produced with internal or external incitement. Rotational flow with... 

In this work, bioleaching was used to extract valuable uranium from a low grade ore. Bioleaching experiments were carried out in batch cultures using a native strain of Acidithiobacillus ferrooxidans. Experiments were conducted to investigate the effects of rotation speed, initial redox potential, initially added Fe concentration, particle size, pH, temperature, pulp density, and culture type. In the shake flask systems, over 99% of the uranium was bioleached in 48 hours at some conditions. Uninoculated flasks gave only around 25% leaching. At each study, uranium and iron concentrations, solution oxidation– reduction potential and pH were measured. The results showed that 150 rpm, d80=100 ... 

In many uranium mines such as gachin-bandarabbas, sulfuric acid is used for leaching operation on ore after crushing operation. This leach liquor, containing uranium, is extracted by specific solvent, including extractant like TOA. However, this operation, named Amex, have been used for many years, there is a vacancy for a detailed thermodynamical studying on uranium extraction from leach liquor.To have a thermodynamical model, we need information about the equilibrium concentration of all the components that may have effect on uranium extraction and also concentration of solvent, pH, phase ratio and activity coefficient alteration. This model must have the ability to predict the equilibrium... 

Pulsed packed columns are among the most important devices used in liquid-liquid extraction, with wide application in petroleum and petrochemical industries, metal salt extraction, pharmaceutical industries, metallurgy, and other areas. Liquid-membrane technology is an alternative separation technique to the liquid-liquid extraction for the extraction and recovery of metal ions from aqueous solutions. There are three main types of liquid membranes: emulsion liquid membrane (ELM), Bulk Liquid Membrane (BLM), and Supported Liquid Membrane (SLM). Liquid emulsion membrane is one of the pertraction methods with phase dispersion. It is a three-phase dispersion system, consisting: external phase,... 

In the present study, smart anticorrosion coatings were successfully prepared based on epoxy ester (EPE) resin and conductive nano polyaniline particles (nES). Anticorrosion behaviors of these coatings were analyzed by electrochemical techniques. Generally, this thesis consists of two main parts: the theoretical studies (1st and 2nd Chaps.) and empirical investigations (3th to 8th Chaps.).The first Chap. expresses a basic introduction about the corrosion concepts and different types of anticorrosion coating. In the second Chap. main goals and stage works of the thesis about the smart anticorrosion coatings are introduced considering literature researches. The subject of the 3th Chap. is... 

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.... 

In this work bioleaching of vanadium has been done from Saghand Ore (Anomaly II). Leaching of vanadium was done in several stages. First, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxxidans were used for dissolution of pure vanadium pentoxide and it was observed that these bacteria are able to dissolve and reduce vanadium with high efficiency. After that these bacteria were employed to leaching of vanadium from ore; however there were no results by those experiments and no vanadium dissolved in liquor although bacterial activity was visible. In the second stage, oxalic acid 0.1 M as an organic acid and three inorganic acids, namely sulfuric, hydrochloridric and nitric acids, in... 

In order to investigate the effect of molecular-structural properties of asphaltene fraction on changes in wettability and flow of crude oil in the porous medium, four crude oil samples from oil fields in southern Iran were tested ;To know the characteristics of crude oil, molecular-structural properties of asphaltene fraction and the effect of asphaltene fraction on the wettability properties of surface, Experiments such as crude oil density and viscosity measurement, crude oil hydrocarbon analysis, asphaltene extraction with standard IP-143 method, elemental analysis and metal content, gel permeation chromatography, nuclear magnetic resonance, interaction between rock and asphaltene....