Sharif Digital Repository

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... 

Generally, predicting the adsorption and Catalytic characteristics of the solids base on the primary principles is impossible; this is only possible for small molecules and single crystal surfaces. On the other hand, phenomenological approaches, which are based on experimental data, are efficient approaches in many cases. The best predictions and designs are done by those who have an extensive information “resources” about the “Reactive Substances- Catalytic-conditions” and are able to “analyze” the data based on the “chemical physical Models”. A Neural network is an extremely simplified model of the human brain that predicts a complex characteristic(s) from a series of primary... 

In this work heterogenization of manganese porphyrins in ZIF-8 and Mg-Al-LDHs structures is performed, via host-guest interactions, and their catalytic activities for olefins epoxidation are also investigated.A heterogenized meso-tetrakis(2,3-dihydroxyphenyl)porphyrinatomanganese(III) acetate at zeolite imidazolate framework-8 (T(2,3-OHP)PorMn@ZIF-8) is investigated in the catalytic olefin epoxidation reactions at room temperature at the first part. Heterogenization is done through a non-classical hydrogen bond proposed between T(2,3-OHP)PorMn bearing O-H groups and C-H of the 2-methylimidazolate linkers in ZIF-8 structure. The aforementioned compound characterized by X-ray powder... 

Modified zeolitic nanostructures were prepared by sol-gel, hydrothermal and coprecipitation methods. At first step, natural zeolite was used as a support for preparing the Ag/AgBr/TiO2 photocatalysts. Their photocatalytic properties were studied by degradation of pollutants and microorganism inactivation at the presence of different illumination source. These processes were mechanistically investigated and the results were explained. At second step, mordenite anocrystals, which synthesized by hydrothermal method, were used as an effective support to prepare the AgX/TiO2/MOR photocatalysts. Photocatalytic degradation of an azo dye performed over these nanocomposites and a mechanism suggested... 

Leachate migration from solid waste landfills into the subsurface environment is one of the significant problems of landfills. This can cause lots of problems for local soil and water to sources according to the contaminants appear in the leachate. Usually, landfill sites include at least one compact clay liner to prevent contamination of groundwater by produced leachate. Over the last decades investigators have been attracted to the structure and removal capacity of this liner. In this study, the effect of the addition of Zeolite to Kaolinite soil for the removal of heavy metal (manganese and zinc) from landfill leachate and the effect of decreasing the thickness of the soil layer has been... 

This project simulates the absorption of carbon dioxide absorbent on 4A zeolite is carried out using Monte Carlo simulation. VBA is a programming language and software used. Grand Canonical simulations performed on a set of particles (Grand Canonical) intended to present new algorithms and computational simulations are presented. Density fluctuations in the algorithms used and the smallest value of less than 0.2 is considered. In the new method of modeling, simulation node cell packing and moving is done on a given node. Adsorption density results obtained from the simulation carried out shows that the adsorption process is the logical and reasonable. Also, the part of the validation of the... 

Advances in genetics and biology have led to the ability to produce therapeutic genes and modify defective genes in patients' genomes, resulting in a solution to many genetic diseases. Many genetic diseases can be overcome through gene therapy by transferring therapeutic genes into the cell nucleus. However, researchers have not yet been able to develop a safe, high-efficiency carrier for the transfer of genes to the target cell, and this has become a bottleneck for the clinical applications of gene therapy. In this study, the ZIF-8 organic-metallic framework was used as a new vector for the transfer of therapeutic genes to target cells. For this purpose, ZIF-8 was synthesized by a... 

In the present work, a series of nanohybrids based on ZIF-8 as a physicochemical stable metal-organic framework (MOF) and different amounts of Chitosan (CS) (0.5–15 wt%) were synthesized and used as adsorbents for anionic (Congo Red, CR) and cationic (malachite green, MG) dyes from contaminated water in single and binary dye solutions. The single adsorbents and their nanohybrids were characterized by FESEM, FTIR, XRD, TGA, BET, and zeta potential measurements. The experimental adsorption results displayed that the synthesized nanohybrids presented higher adsorption capacity for anionic dyes compared to cationic dyes in both single and binary dye solutions. It was deduced that the... 

The adsorption equilibria of carbon dioxide, methane, and nitrogen on pelletized cation-exchanged faujasite zeolite (with alkali, alkaline earth, and transition metal ions) have been investigated by a volumetric apparatus. The standard instrumental analytical techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray spectroscopy (EDX), and atomic absorption spectroscopy (AAS) were utilized to characterize binder-free modified zeolites. The EDX spectra and AAS results revealed that the ion-exchange was successfully achieved with expected tendencies. The results indicate that the type of cation present in the zeolite... 

Olefin/ paraffin separation is one of the most important processes in the petrochemical industries.In the last decades, adsorption and membrane processes are a new technology considered significantly for this purpose. In order to synthesizeof zeolite powder (pure silica zeolite STT and CHA), raw materials were made by two methods and their HNMR spectrum was recorded and thenzeolite powder was synthesized. X ray diffraction(XRD) and scanning electron microscopy (SEM) images were taken,showing the same results as the refference structure.To consider synthesized zeolite powdersand olefin/ paraffin interactions, surface adsorption ofthose gases was accomplished on two zeolite powders. After... 

Polyagent photocatalysts based on the zeolite including TiO2, Ag and AgBr prepared by Sol-gel method. Ag and AgBr prevent of electron-hole recombination and enhance photocatalytic activity. Prepared catalysts were characterized by different analysis method including XRD, SEM, EDX, FTIR and BET techniques. Catalyst activities were investigated from two aspects: in first step the activities of catalyst were investigated for degradation of AB92 dye. The effect of different factors such as: catalyst concentration, dye concentration, pH and scavenger (sodium thiosulphate) on efficiency and reaction rate were investigated. The optimazed values for all conditions specified, then catalyst activities... 

Nowadays, metal-organic frameworks have received a lot of attention due to their properties and characteristics such as controllable structure, high specific surface area and the tunable porosity size and have found many applications. One group of metal-organic frameworks are zeolitic imidazolate frameworks which ZIF-8 is a member of this family, and many studies have been conducted on it. In the present study, ZIF-8 nanocomposite coating was applied to the plain carbon steel substrate by synthesis at room temperature and immersion method, and its corrosion behavior and mechanical properties were investigated. The effect of Mercaptobenzothiazole (MBT) inhibitor on corrosion behavior and... 

In this project Mordinate and Eu-1 zeolite were synthesized by hydrothermal method and then bifunctional catalysts including acid-base zeolite and Pt-Al2O3 metal base were mixed and made using a planetary mill. The modified catalysts were detected by various methods such as XRD, SEM, FTIR. The aim of this project is to synthesize and characterize the modified catalysts and to escalate their catalytic properties. Our focus is primarily on the synthesis of zeolite-based catalysts modified with unique features such as having active acid sites, high thermal stability and appropriate selectivity for the purpose of investigating the mechanism and kinetics of the C8 aromatic Compounds... 

Nanoporous metal-organic frameworks are among the new and advanced compounds that have attracted attention of researchers due to their unique properties such as high surface area, high porosity and regular structure. These compounds can catalyze and degrade pollutants. Due to the high consumption of organic compounds, especially textile dyes, the pollution caused by wastewater is increasing in various industries. Disposal of wastewater containing organic pollutants into aquatic environments can alter the natural color, change the taste of water and disturb the life of living organisms. If the dyes are left untreated in aquatic ecosystems, they can remain in the environment for a very long... 

Environmental destructive effects of gases caused by combustion of sulfur compounds in the fuel, poisoning of catalysts, corrosion of equipment, as well as intensification of environmental considerations and new standards adopted for maximum sulfur content has made the desulfurization of fuels important; The desulfurization method using hydrogen has a high potential to remove sulfur. One of the major challenges in this process is to find the proper catalyst that has the best performance for this process. Ni (or Co) Mo (or W)/ γ-Al2O3 catalysts have high potential for using as a catalyst for the desulfurization process from a variety of large-scale or industrial hydrocarbon cuts. According to... 

During the past few years, hexavalent chromium (Cr(VI)) is of environmental concern due to its high toxicity and mobility. Therefore, removing it from industrial wastewater is of chief significance. In this research, efficient photocatalyst materials (xµLTiO2NPs@ZIF-8) for the reduction of Cr(VI) from water resources were firstly synthesized. This composite was prepared by an in situ method with zeolitic imidazolate framework-8 as the matrix. TiO2 and ZIF-8 were selected for their excellent stability in aqueous media, high photoactivity, non-toxicity, and high surface area. The structure of the as-synthesized materials was characterized by X-ray powder diffraction (XRD), scanning electron... 

Zeolite membranes are of interest due to their special properties; thermal and mechanical resistances and non-plasticization property in gas separations. Therefore, separation of H2S from natural gas by these membranes is the main goal of this thesis which is not investigated in the world. After some theoretical investigations including diffusion mechanisms of gases in the zeolites and adsorption mechanism of H2S on the zeolites, pure silica CHA-type (Si-CHA) zeolite was selected. After successful synthesis of Si-CHA zeolite, adsorption isotherms of H2S, CO2, and CH4 on the Si-CHA zeolite were measured over pressure range of 0-190 kPa and temperatures of 25 °C, 50 °C, and 75 °C. Acid gases... 

Today, due to the decreasing of fossil fuel reserves and the need to use clean fuels, hydrogen is a suitable alternative, and hydrogen production has received considerable attention. One of the best methods of hydrogen production is water splitting. Overall water splitting can be divided into two half reactions including the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which selecting the appropriate electrocatalyst for these half reactions plays an important role. The four-electron transfer process in OER leads to slow kinetics of the reaction and a large overpotential. The noble metal-based oxides, including IrO2 and RuO2, are known as outstanding OER... 

This study has concentrated on preparation of mixed matrix membranes (MMMs) in order to improve the separation performance of the neat poly(amide-12-b-ethylene oxide)(Pebax1074) membrane. Pebax1074 and zeolite SAPO-34 were used to fabricate MMM for the first time. Micro-size SAPO-34 was added to polymer matrix up to 35wt% based on polymer weight; even though at this high loading percentage the prepared membranes were not stable enough to be tested for characterization and gas permeation. The obtained results showed more than 30% increment in CO2 permeability, along with slight growth and reduction in N2 and CH4 permeabilities, respectively for 30wt% zeolite content membranes. Permeability... 

Mixed matrix membranes (MMMs) are new generation of membranes which possess simple processability of polymeric membranes and high separation ability of zeolitic membranes. The present study, concentrates on the fabrication of MMM for CO2/CH4 separation in a combined method as encompasses not only higher permeability but also superior selectivity in comparison with conventional polymeric membranes. The most appropriate technique for MMM making, is the process which provides participation of distributed zeolite particles in separation efficiently while the polymeric matrix acts just like a particle support and dose not play an effective role in separation. Investigations demonstrates that...