Sharif Digital Repository

The major obstacle in using natural gas as a clean and abundant fuel in transportation industries is the low density of energy obtained from its combustion. Adsorbed Natural Gas (ANG) is a useful method to increase the energy density and store the natural gas. The lower cost and higher safety have made it different from the other storage technologies. In addition, ANG can be useful to solve the lack of gas in the peak of consumption. Among all adsorbents, Activated Carbon (AC) has shown the highest adsorption capacity of natural gas. In the present project, walnut shell has been used as the precursor in the chemical synthesise of AC. The main effective factors in chemical activation, such as... 

Natural gas (NG) has emerged as an alternative energy source in transportation sector as it provides clean combustion and hence lowers exhaust pollution. NG can be stored as an adsorbed phase in porous materials and is referred to ANG. The use of adsorbent materials for storing NG, at relatively low pressure (3.5–4 MPa), is a possibility for making ANG technology competitive with CNG. Among all adsorbents, carbon nanostructures with pore diameter (0.8-1.4 nm) has shown the highest adsorption capacity of natural gas. In the present study, cellulose has been used as the carbonaceous precursor and Activated Carbon (AC) has been prepared using hydrothermal carbonization of cellulose followed by... 

Due to the increase in greenhouse gases in earth’s atmosphere in recent years and its devastating environmental outcomes, there has been an increase in research trying to reduce these gases especially CO2. Flue gas is one of the most important sources of CO2 emission. Among the many techniques of removal, capturing and CO2 separation from flue gas, physical adsorption by a solid adsorbent is considered as a suitable and economic option. Among the solid adsorbent that are used for adsorption of CO2, Metal-Organic frameworks have many interesting features such as high specific surface area and high internal free volume. Among the Metal-Organic frameworks, MIL-53 (Al) and MIL-101 (Cr) are two... 

The effectiveness of activated bentonite, known as Clay, is studied in the process of removal of olefins from aromatics. The study on this subject can be divided in two categories: catalysis and process section. The catalyst activities is evaluated with the production of clay samples that are activated by sulfuric acid and hydrochloric acid. The performance and life time of the acid treated are characterized by XRD, XRF, BET, Pyridine FTIR analysis, SEM images and pilot test of the samples. In the process section, factors that are affecting the life time and performance of the catalytic activity of Clay are investigated and the effect of each known parameter on the operating time of this... 

In this project, using experimental results for permeation of gases H2, He, N2, and CO on a microporous membrane (the applied sample was a ceramic membrane) and modified equations, pore diameter, tortuosity, and porosity were determined for this type of membrane. Furthermore, pore diameter, critical volume, and characteristic energy of a carbon molecular sieve membrane were calculated using experimental data for CO2 adsorption on this type of membrane. Diffusivities of CO2, N2, and Ar were also calculated by means of the uptake, time lag/adsorption, and permeability/adsorption tests on carbon molecular sieve membranes utilizing experimental data obtained for this type of membranes and the... 

gas adsorption in porous solids and adsorbent,is the important cases in gas processing industries. Including the removal of compounds such as carbon dioxide, hydrogen sulfide and mercaptans from sour gas in natural gas sweetening industry is of great importance.Also in solving the greenhouse phenomena extraction of gases such as methane and carbon dioxide of important environmental issues.To understand and predict the behavior of the absorption capacity of various adsorbents and thus the possibility of absorption systems, a mathematical model is needed.Library resources available in order to determine the kinetics and thermodynamic processes of gas adsorption on solid absorbents use... 

In this thesis, it reports the fabrication of novel magnetic nanocomposites combining the unique properties of magnetic nanoparticles and cross-linked basic polymers that their surface functionalized by suitable groups such as carboxylate groups, pentaethylenehexamine and so on to achieve the maximum adsorption capacity of dyes and heavy metal ions. The performance of the magnetic nanocomposites for removal of anionic and cationic dyes and heavy metal ions were evaluated in different conditions of pH, contact time and initial concentrations. Moreover, the adsorption mechanism was investigated by kinetic models and isotherm studies. The results showed that the abovementioned adsorbents can... 

Heavy metals such as lead, chromium, nickel are considered as environmental pollutants. These substances are highly toxic and dangerous to humans and other organisms at low concentrations and many problems are caused by them. Chromium belongs to the group of heavy and toxic metals. Form 6-valent chromium for humans is considered a definite carcinogen and also creates other problems. One common method of chromium removal is chemical precipitation which caused a large volume of waste. Other methods such as ion exchange, solvent extraction, reverse osmosis and biological methods are used to remove chromium. Adsorption is another effective method with very few disadvantages compared to other... 

In the current situation of energy, gas storage is one of the basic needs. Different methods have been used in order to storage gases. One of these methods is the adsorption of gases on solid materials, which are called as adsorbents. In recent decades, different gas adsorbents, such as silica gel, zeolite and activated carbon, have been studied. Most of these adsorbents are nonorganic materials. Recently, many researchers have tried to apply polymeric materials as gas adsorbents. In this regard, the obtained results on the different polymers showed that it is possible to achieve the proper gas adsorption. In this study, different samples were prepared from polysulfone by phase inversion...