Sharif Digital Repository

In this thesis, a novel graphene oxide (GO)/sodium alginate (SA)/polyacrylamide (PAM) ternary nanocomposite hydrogel with excellent mechanical performance has been fabricated through freeradical polymerization of acrylamide (AAm) and SA in the presence of GO in an aqueous system followed with ionically crosslinking of calcium ions. Physical and chemical characteristics of the composite were investigated by Fourier transform infrared spectroscopy and scanning electron microscopy. The swelling behaviors of the composite hydrogels were investigated under varying conditions of time and pH. The optimized swelling capacity in standard conditions was found to be 1711% per gram of the hydrogel. The... 

Resin In Pulp(RIP) is One of the most important processes for separation of uranium from ore while concentration of uranium in ore is low , based on adsorption of uranium that exist in the slurry on onion exchanger resins .uranium ore is dissolved in sulfuric acid and slurry that contain uranium is produced,then this slurry enter stirred reactors and adsorption process is performed.RIP are accepted universally and now adays countries such as canada,south africa and australia use this process when concentration of uranium in slurry after leaching process is 100-500 ppm.in iran also this process is performing in ardacan-saghand mine.Kinetic of adsorption process in stirred reactors has been... 

One of the main uranium separations of ore that uranium percent application of enhanced design strategies in the industrial cracking furnaces are of practical interest for oil, gas and petrochemical industries. For such engineering purposes the exact simulation of temperature, species concentration and flow fields in the furnace is essential. In this paper, a study was performed to simulate 3D flue gas flow pattern, temperature and species concentration field in the radiation section of an industrial cracking furnace using the computational fluid dynamics (100-500) ppm technique. The steady-state Reynolds Averaged Navier–Stokes (Resin in pulp)equations were solved, in a finite volume scheme,... 

In this study graphene and graphene adsorbent for the Co2+ ion were created from sodium phenoxide and calcium phenoxide, respectively, using the chemical vapor deposition method, and their chemical, physical, and morphological properties were investigated using FT-IR, UV, XRD, Raman, TEM, FE-SEM, and XPS. The results suggest that the optimum reaction condition for synthesizing mono-layer and multi-layer graphene is the 750 °C temperature for 30 min. The Co2+ adsorbing properties of the synthesized graphene adsorbent from calcium phenoxide was investigated. The investigation of solvation properties suggests insolubility above 650 °C and the kinetic data suggest the rapidness of the Co2+... 

The amino groups present in the chemical structure of chitosan have made this material a prominent dye absorbents. But researchers have always taken steps to improve conditions and increase absorption. One of the materials that has attracted most researchers today is metal-organic frameworks. These porous materials with high surface area, optimum thermal resistance and adsorbent dye functional groups have been used as the reinfocing in the chitosan polymer field to adsorb anionic dye (methyl orange) from the aqueous media. One of metal-organic frameworks is UiO-66, which was selected as a reinforcing phase in the polymer field, due to its good stability in aqueous solutions, good thermal... 

In recent years, desulfurization has received much attention due to its devastating environmental effects. The existence of sulfur compounds has effects such as corrosion, poisoning of catalysts, reduction of heat of combustion and reduction of price. Sulfur compounds in hydrocarbon fuels also produce sulfur oxides caused by combustion then they enter the atmosphere, and cause acid rain. Acid rain dissolves building materials, poisons lakes, and destroys forests. Therefore, removing sulfur or converting it to less harmful substances is one of the most important processes in refineries. The method studied in this research is the use of adsorption desulfurization method by microchannel which... 

Hydrogen gas is considered as a clean fuel and energy carrier that its storage for future uses is a challenging issue. One of the methods to store it, is adsorption on a group of adsorbents called metal-organic frameworks. In this research, one of these frameworks called ZIF-8, has been selected to study hydrogen storage capability. To evaluate the effect of having two metals, a mixture of two metals was used in the synthesis process. To characterize the structure of the synthesized adsorbents, X-ray powder diffraction (XRD),adsorption and desorption of nitrogen at temperature of 77 K, Field Emission Scanning Electron Microscopy (FESEM), energy-dispersive X-ray Spectroscopy (EDS) and... 

Asphaltene deposition, the heaviest and most polar component of crude oil, which causes great economic damage inside the reservoir, near wells, pipelines and well equipment, is an important challenge in the production of oil reservoirs. The main purpose of this study is to prob the adsorption kinetics and the mechanism of asphaltene adsorption on the metal surface by a quartz crystal microbalance device under different conditions of temperature, flow rate and degree of asphaltene instability. In this study, indirect uv-vis spectroscopic method was used to determine the onset of asphaltene precipitation, then experiments were designed using Taguchi method. A new QCM device has been designed... 

Reprocessing of different industrial and agricultural wastes become very Important in today’s world because it reduces the environmental pollution arising from waste accumulation as well as providing cheap and sustainable raw material for industries.Among different wastes, sugarcane bagasse is produced in large quantities in Iran specially in Khuzestan province. Bagasse is mainly consists of 3 natural polymers;cellulose, hemicellulose and lignin and can be used for production of chipboard and MDFs, activated carbon, bioethanol and acid citric The purpose of this research is the synthesis of porous nitrogen-doped carbon materials from bagasse wastes and investigate the use of these compounds... 

The current study was attributed to uranium uptake by Varion-AP resin from Saghand, Iran Uranium Mine, ore leach liquor. A suitable high-efficiency system was designed for continuous ion exchange at the bench scale and the uranium uptake parameters were optimized. In this system, 1 reactors was used with a volume of 3 liters in stage with the same height difference. A leach liquor containing uranium with a concentration of between 200 and 300 mg/l was flowed from the feed storage by gravity between reactor 1 to 10 at a flow rate of 30 lit/h and Varion-AP resin was transferred in counter-current flow from stage 10 to 1 by a pneumatic pump. The output of each reactor had a screener that... 

In this dissertation, Hydrogen storage in the solids based was investigated. The carbon-based structure used is the graphene that decorated with metal atoms to increase intermolecular interactions and increase the adsorption weight capacity. The structure of graphene has been considered due to its properties such as low density, high heat transfer coefficient and high specific surface area. Initially, the structure of pure graphene was investigated using the molecular dynamics method for hydrogen storage and it was shown that the interaction between hydrogen molecules and pure graphene is very weak and it can’t be a good option for use in cars. Then, the structures of graphene reinforced... 

Today, recycling lithium as a valuable metal from brine plays an important role in various applications such as battery manufacturing, computers, aerospace and automobiles. Among the aqueous methods available for the extraction of the lithium element in brines, ion exchange by TiO2 nanosorbents is one of the most efficient methods. In this study, first the titanium dioxide nanotubes were well synthesized by anodizing method and the nanograss created after the anodizing process were completely eliminated. Then, the effect of three cathodes of aluminum, graphite and stainless steel in order to select the best cathode and achieve a regular morphology as well as their replacement with platinum... 

Sulfur oxides are categorized as one of the most important poisoning and activity-reducer groups acting on the catalytic converters present in the exhaust treatment systems. In the present work, interactions of the SOX species with diesel oxidation catalysts (DOCs) are investigated by implementing a kinetic modeling approach. Experimental data obtained from a catalyst of this type, i.e., Pt/γ-Al2O3, was employed and a multi-step microkinetic model was developed in Matlab 2018b® to proxy the poisoning effect of the adsorption of surface sulfur species and their desorption behavior. The microkinetic model was run to describe the individual SO2 and SO3 adsorption-desorption process using the... 

Physical processes such as adsorption and membrane filtration are in progress and considered as efficient methods in separation and treatment of organic pollutants from petrochemical and colored wastewaters. The advantages of these methods include high energy efficiency, low cost, facile process, and regeneration and implementation ability for a wide range of contaminants. Nevertheless,requirement of suitable materials as adsorbents with high adsorption capacity, capability of preparing membranes based on these materials, optimization of process conditions and removal improvement have still remained as the main challenges; therefore, these topics have been mentioned as main aims of this... 

Sulfur dioxide is known as an acidic gas and one of the standard pollutants in determining air quality. This gas mostly enters into the atmosphere by flue gas causing many environmental problems. In order to remove this gas, various methods are used. One of the suitable methods to reduce the emission of this pollutant in low concentrations is the use of Metal-Organic Frameworks (MOF) as an adsorbent. One of these Metal-Organic Frameworks is NH2-MIL-53(Al) that owing to its relatively good stability under wet and acidic conditions, has been chosen to adsorb sulfur dioxide in this research. In most studies on SO2 adsorption, often MOFs with a long synthesis time, high synthesis cost, and/or... 

Phenolic compounds, which are one of the most dangerous compounds for the environment, are present in many effluents of various industries such as petrochemicals and pharmaceuticals, and the need to eliminate these compounds is increasingly felt. In this study, adsorption of three compounds of para-chlorophenol, para-nitrophenol and hydroquinone on polypyrrole adsorbent in the form of neutral, charged, copolymer with polyaniline and phosphorus-doped have been investigated using density functional theory (DFT). Calculations are performed at two levels of b3lyp/6-31+G(d,p) and wb97xd/631+G(d,p) for two different orientations of adsorbate molecules that the correlation-exchange function wb97xd... 

Although much progress has been made in eliminating, conserving, and reducing migration and emissions of radioactive materials, the risk of radioactive material release into the environment is still one of the most important hazards in the use of nuclear energy. In this study, graphene compounds have been used as adsorbents for the removal of radioactive materials due to their high level, cost-effectiveness and simplicity of the synthesis process of various composites. In this regard, the removal of strontium and cobalt by graphene compounds has been investigated. Magnetite nanoparticles were anchored on the surface of graphene by sol-gel method and adsorption in batch mode was investigated.... 

Today, the pollution of heavy metals in wastewater and surface waters, which is a global environmental problem, has increased with the expansion of various industrial activities. Heavy metals cause serious health problems due to their accumulation in human and animal tissues. Thorium, is a radioactive element with an atomic number of 90 that is widely used in the optics, aerospace, metallurgy and chemical industries, in the manufacture of high-strength alloys, in UV photocells, and especially in the nuclear industry. The primary sources of radioactive wastewater include nuclear power plants, nuclear energy industry research centers, medical institutions, industrial production, universities,... 

This research aims to extract lithium from brines with low concentrations. Aluminum hydroxide has been chosen as a suitable and selective adsorbent. This absorbent is made by combining one of the aluminum salts in an alkaline environment. Due to the high cost of providing the raw materials for making the absorbent and sensitivity to the pH value and environmental harm, it is suggested that the absorbent be made by hydrolysis of water by aluminum particles. The manufacturing method has shown promising results in such a way that with the combination of NaCl+CaO and aluminum and activation by ball mill, the amount of extraction is 97% at a temperature of 40 ˚C; in two days, the molar ratio of... 

Molybdenum is one of the important elements of the intermediary metal with atomic number 42, which is used in various industries, but among the important uses of this metal in the nuclear industry, we can mention the presence of this element in the production of yellow cake as an impurity and also as a precursor for the production of radiopharmaceuticals. It is one of the impurities that remain in all stages of yellow cake production along with uranium, and the high presence of this element causes the centrifuges to become unbalanced during the injection of "U" "F" _"6" gas, and on the other hand, technetium, the main ingredient in the production of radiopharmaceuticals, It comes from the...