جستجوی مقالات مرتبط با کلیدواژه « نانوفناوری » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

Oil-based products have led to a brilliant and magnificent civilization for the development of human society, but these materials have also caused serious damage to the environment and human health. Food coating with biodegradable polymers and nanomaterials can increase the preservation of nutritional value and shelf-life, improve the quality, and increase food safety, and can be a natural and suitable alternative to common plastic materials used in packaging industry. Ensuring the protection of the quality and taste of food products, increasing the durability, and reducing the packaging wastes is the priority of researchers. Synthetic plastics are widely used, especially in food packaging industry, and cause problems in disposal and recycling. These issues have caused increasing concerns about environmental pollution and destruction. Therefore, it is possible to address these challenges by developing of biodegradable polymers and nanomaterials. In addition, consumers demand sustainable (durable) packaging materials that reduce the environmental problems associated with plastic wastes. In this article, the applications of nanomaterials and biodegradable polymers in the packaging of food products are reviewed. In these composite materials, effective nanoparticles (i.e., gold, copper, copper oxide, and silver nanoparticles) have combined with biodegradable and eco-friendly polymers (i.e., gelatin and cellulose obtained from natural resources).

Gas-liquid membrane contactors are promising alternatives to conventional absorption technologies. However, despite their significant advantages, such systems face the major problem of gradual wetting of the porous polymeric membranes with liquid absorbents. In fact, wetting of porous polymeric membranes by liquid absorbents increases the mass transfer resistance of the membrane phase, which in turn, reduces the gas absorption efficiency. Accordingly, in this paper, the effect of membrane wetting on mass transfer resistance and absorption efficiency has been studied. The influence of effective parameters on membrane wetting phenomenon, such as absorbent and membrane properties, is investigated. In addition, different prevention methods of membrane wetting is discussed in detail. The results show the increase in the rate of wetting at high velocity and pressure of the absorbent. In the case of absorbents-containing organic compounds, their surface tension is decreased rapidly with the increasing concentration of organic compounds, which increased the wetting rate of the membrane. In addition, studies on various polymeric membranes have shown that the structural and chemical changes of the membrane surface, which occur due to long-term contact of the membranes with amine absorbents, strongly increase the wetting of the membranes, and thus, its functionality. Moreover, studies have shown that modifying the surface of membranes is one of the most effective methods to prevent the problem of wetting. By modifying the surface, the free energy of the membrane surface can be reduced and its roughness can be increased, thus increasing the hydrophobicity of the membrane surface. Among these, nanotechnology has been introduced as one of the most important technologies in the production of superhydrophobic membranes to prevent the problem of wetting the porous polymeric membranes.

Asphaltene precipitation/deposition in reservoir formation has detrimental influences on the oil production. The stability of w/o emulsions, the high viscosity of oil, and unfavorably changing the reservoir rock properties are induced in part by the asphaltene instability. Nanoparticles exhibit acceptable capacities for the adsorption and control of the precipitation of asphaltene. In this study, in-situ synthesis of iron oxide nanoparticles in reservoir oils has been followed to evaluate the effects of the thus-prepared nanoparticles on the control of asphaltene damage in tight carbonate core plugs. Model oil has been prepared by dissolving dead oil in a toluene/gasoil mixture. Following the preparation of stable emulsions of precursor iron salt aqueous solution in the model oil, Fe2O3 nanoparticles have been synthesized at a typical reservoir temperature and high-enough pressure in an autoclave. Two series of core-flooding experiments have been performed by the injection of n-C6 and monitoring the hydrocarbon effective permeability before and after the damage. Two core plugs with the same flow zone index have been selected, one of which has been saturated with the model oil and the other with the emulsion, and the asphaltene damage has been induced by the core flooding test. The results of XRD and FESEM have indicated the crystalline structure and the mean particle size of 65 nm for the in-situ prepared nanoparticles, much smaller than the pore/throat sizes of the plugs. It is found out that the nanoparticles are effective in the control of the asphaltene damage at high injection/production flowrates. However, at low drawdown or injection/production flowrates, the in-situ synthesis procedure leads to a higher drop in the hydrocarbon effective permeability when compared to that observed during the displacement of the virgin model oil. Finally, this may be ascribed to the trapping of aqueous droplets in pore-throats, resulting in a significant reduction in the hydrocarbon permeability by the phase trapping.

Adsorptive desulfurization using mesoporous carbons are of the preeminent methods to meet serious international standards in case of sulfur. In this research, the absorbent CMK-3 containing nickel nanoparticles was synthesized and characterization using XRD, BET, SEM and FT-IR. The results showed that the nanostructure was formed and the despite high nickel loading, structural order is still preserved and specific surface of the synthesized samples is maintained at an acceptable level. Then, in the next step, the capability of synthesized adsorbent was carried out in various conditions, which shows the significant yield of them in both low and high temperature. In addition, the absorption yield of these nano-adsorbents was preserved after several reduction, indicating the high potential of these adsorbents in desulphurization.

Due to the growing demand in the oil industry, the application of enhanced oil recovery (EOR) techniques for oil reservoirs to meet the needs of communities is essential. nowadays, nanotechnology is growing rapidly and it contribute significantly to the technological advances in many industries and in various oil and gas fields such as exploration, drilling, enhanced oil recovery and refining and distribution. In this paper, the effect of nanoparticles, nanoemulsions, nanofilters, nanogels, nanosensors, nanorobots, and nanocatalysts in enhanced oil recovery and oil reservoirs progress and new achievements in this field are discussed. The results show that, nanotechnology has the potential to change the common methods of EOR by improving geomechanics of the reservoir and surface tension alongside modification of oil reservoirs. Today, this subject has attracted the attention of many researchers.

Surface properties sometimes play a more important role in the function of polymer materials than do the bulk of polymer materials. The surface structure of fibres is of the great importance for the properties of fibres and textiles in processing and use. Because many functions of the polymer materials، e. g. friction، adhesion، adsorption، and liquid penetration، dye ability، hydrophilicity and hydrophobicity related to the topmost layer of the materials. In order to develop textile materials with the desired performance، the surface of fibres is often modified with polymer coatings before use. Water and soil repellency has been one of the major targets for fiber and textile scientists and manufacturers for centuries. To attain limited wettability، in addition to use of a layer with low surface energy، it is necessary to change surface structure in nano-micro scales. These surfaces are known as superhydrophobic surfaces with properties such as lotus leaves. To fabricate superhydrophobic surface on metal، glass، polymer and textiles، many methods and materials are examined to create proper surface roughness and low surface energy، respectivelly. In this review paper، production and properties of superhydrophobic textiles are reported.

Recently nano zero valent iron (NZVI) because of its unique electrical, magnetic, optical and catalytic properties and also because of its high surface area and activity, resulted from its small size, has been lionized. Rapid development in nanotechnology has caused increased number of research works about NZVI applications especially for environmental purposes. The synthesis method of nanoparticles is determinant parameter of their size and structure. Researchers have used various methods for NZVI synthesis. These methods are divided to chemical and physical categories. In the present study we review the synthesis methods of NZVI.

This research is a report on nowadays situation of solar energy in the world and methods which nanotechnology could increase the efficiency of solar cells. Because of increasing price and instability in fuels market, researches have been developed about replacement energies. Solar energy is one of these replacement sources, that is reachable in most of the world. so it always have been in survey and research via scientists. Problems in the using of this kind of energy are including: low efficiency of solar cells and their expensive costs. Recent researches showed that using of nanoparticles in solar cells manufacturing can improve this situation. This review explains the basic activities to usage of nanotechnology in production and improvement of solar cells.