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We report a scalable method to obtain a new material where large graphene sheets form webs linking carbon fibers. Film-fiber hybrid nonwoven mats are formed during fiber processing and converted to carbon structures after a simple thermal... more
We report a scalable method to obtain a new material where large graphene sheets form webs linking carbon fibers. Film-fiber hybrid nonwoven mats are formed during fiber processing and converted to carbon structures after a simple thermal treatment. This contrasts with multistep methods that attempt to mix previously prepared graphene and fibers, or require complicated and costly processes for deposition of graphene over carbon fibers. The developed graphene-fiber hybrid structures have seamless connections between graphene and fibers, and in fact the graphene "veils" extend directly from one fiber into another forming a continuous surface. The graphene-fiber hybrid structures are produced in situ from aqueous poly(vinyl alcohol) solutions. The solutions were subjected to centrifugal spinning to produce fine nanofiber mats. The addition of salt to the polymer solution stimulated a capillarity effect that promoted the formation of thin veils, which become graphene sheets upon dehydration by sulfuric acid vapor followed by carbonization (at relatively low temperatures, below 800 °C). These veils extend over several micrometers within the pores of the fiber network, and consist of crystalline graphene layers that cross-link the fibers to form a highly interconnected hybrid network. The surface area and pore diameter of the hybrid structures were measured to be 521 m(2)g(-1) and 10 nm, respectively. The resulting structure shows high electrical conductivity, 550 S/m, and promising shielding of electromagnetic interference, making it an attractive system for a broad range of electronic applications.
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ABSTRACT A new model for the excess Gibbs energy of hydrotrope solutions is presented. This model is based on the local composition model by Chen et al. Hydrotropes are usually organic salts that can increase the solubility of organic and... more
ABSTRACT A new model for the excess Gibbs energy of hydrotrope solutions is presented. This model is based on the local composition model by Chen et al. Hydrotropes are usually organic salts that can increase the solubility of organic and inorganic compounds in water. The proposed model has five adjustable parameters; one of them is related to long-range forces, and four of them are related to short-range forces. Long-range forces are modeled by the Pitzer-Debye-Huckel equation. However, in our model, the effect of the molecular solute on the dielectric constant of water has also been considered. Modeling of short-range forces is based on local composition concepts. The model parameters are obtained using experimental data for six hydrotropes with four solutes at different temperatures. The water solubility of molecular solutes in the presence of hydrotropes has been calculated for different systems. Accurate results are obtained. © 2005 American Institute of Chemical Engineers AIChE J, 2006
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... Akia Mandana (1 3) ; Alavi Seyed Mahdi (1) ; Rezaei Mehran (2) ; Yan Zi-Feng (3) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). (1) Chemical Engineering Department,Iran University of Science and Technology, Tehran,... more
... Akia Mandana (1 3) ; Alavi Seyed Mahdi (1) ; Rezaei Mehran (2) ; Yan Zi-Feng (3) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). (1) Chemical Engineering Department,Iran University of Science and Technology, Tehran, Iran (2) Chemical Engineering Department ...
Research Interests: Materials Engineering, Materials Science, Chemistry, Catalysis, Scanning Electron Microscopy, and 14 moreNanomaterials, Porous Materials, Dehydrogenation, Nitrogen, Specific surface area, Surface Area, X ray diffraction, Thermal Stability, Fourier transform infrared spectroscopy, Thermogravimetric Analysis, NITRIC ACID, Hydrothermal treatment, Mesoporous Material, and temperature programmed reduction
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Significant improvements in biomass conversion using nanocatalysts. Feasibility of utilization milder operating conditions by using nanocatalysts compared to the bulk catalysts. The role of nanocatalysts to overcome some challenges in... more
Significant improvements in biomass conversion using nanocatalysts. Feasibility of utilization milder operating conditions by using nanocatalysts compared to the bulk catalysts. The role of nanocatalysts to overcome some challenges in biomass conversion, improving the products quality.
A review on conversion of biomass to biofuel by nanocatalysts
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Research Interests: Materials Engineering, Mechanical Engineering, Chemical Engineering, Materials Science, Fiber, and 9 morepolymer science and Engineering, Carbonization, Electrochemical, Sodium, Scanning Electron Microscope, X Ray Photoelectron Spectroscopy, Polyacrylonitrile, Graphitization, and Centrifugal Spinning
We report a scalable method to obtain a new material where large graphene sheets form webs linking carbon fibers. Film-fiber hybrid nonwoven mats are formed during fiber processing and converted to carbon structures after a simple thermal... more
We report a scalable method to obtain a new material where large graphene sheets form webs linking carbon fibers. Film-fiber hybrid nonwoven mats are formed during fiber processing and converted to carbon structures after a simple thermal treatment. This contrasts with multistep methods that attempt to mix previously prepared graphene and fibers, or require complicated and costly processes for deposition of graphene over carbon fibers. The developed graphene-fiber hybrid structures have seamless connections between graphene and fibers, and in fact the graphene "veils" extend directly from one fiber into another forming a continuous surface. The graphene-fiber hybrid structures are produced in situ from aqueous poly(vinyl alcohol) solutions. The solutions were subjected to centrifugal spinning to produce fine nanofiber mats. The addition of salt to the polymer solution stimulated a capillarity effect that promoted the formation of thin veils, which become graphene sheets up...
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This study presents an optimization of dehydrogenation catalyst components including platinum, indium, and lithium using response surface methodology (RSM).
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ABSTRACT This article compares the effectiveness of pure and modified TiO2 for photocatalytic degradation of different organic matters and clarifies the advantages of the modified TiO2 with photoactivity under visible light.... more
ABSTRACT This article compares the effectiveness of pure and modified TiO2 for photocatalytic degradation of different organic matters and clarifies the advantages of the modified TiO2 with photoactivity under visible light. Photocatalytic degradation technique with titanium dioxide is generally applied for treating wastewater containing refractory organic contaminants with the purpose of reuse due to its ability to achieve complete mineralization of the compounds under mild conditions such as ambient temperature and pressure. Performance of different types of photocatalytic reactors, effects of important parameters on the reactors performance, effect of various methods used to enhance the photocatalytic activity of TiO2 including doping, sensitization of TiO2 and surface modification are discussed in details. So far, a few review papers have been published and extensive information have been reported on the structure and electronic properties of TiO2, difference between TiO2 with other common semiconductors used for photocatalytic applications, various methods used to enhance the photocatalytic characteristics of TiO2 including dye sensitization, doping, coupling, the effects of various operating parameters on the photocatalytic degradation of phenols and dyes and types of reactors, comparison between effective modes of TiO2 application as immobilized on surface or as suspension, and photocatalytic hybrid membrane system are presented. However, in the published review papers, performance of the different modified photocatalysts is rarely compared quantitatively. Therefore, in order to provide an inclusive and effective comparison among the studies, specific removal rate (SRR) (mg compoundremoved/g cat. h) was calculated as a response.
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ABSTRACT In this study, an immobilized nanoTiO2 photocatalyst was developed for the degradation of Tire Cord manufacturing wastewater with low BOD5/COD ratio (0.1–0.2). The interactive effects of three numerical independent factors... more
ABSTRACT In this study, an immobilized nanoTiO2 photocatalyst was developed for the degradation of Tire Cord manufacturing wastewater with low BOD5/COD ratio (0.1–0.2). The interactive effects of three numerical independent factors (initial COD concentration, initial pH, and reaction time) on the process performance were studied. The process performance was evaluated by monitoring three process responses including COD removal efficiency, specific COD removal rate and BOD5/COD ratio after treatment. The process was modeled and analyzed using response surface methodology. Maximum COD removal efficiency and BOD5/COD ratio were modeled to be 38% and 0.5, respectively, at CODin of 350 mg/l and initial pH of 11. The photocatalytic process induced by O3 and O3/H2O2 showed a remarkable improvement in the process responses studied. Photocatalytic process with sequence regeneration with ozonation could achieve higher COD removal efficiency and BOD5/COD ratio relative to that obtained from regeneration by aeration.
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... Akia Mandana (1 3) ; Alavi Seyed Mahdi (1) ; Rezaei Mehran (2) ; Yan Zi-Feng (3) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). (1) Chemical Engineering Department,Iran University of Science and Technology, Tehran,... more
... Akia Mandana (1 3) ; Alavi Seyed Mahdi (1) ; Rezaei Mehran (2) ; Yan Zi-Feng (3) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). (1) Chemical Engineering Department,Iran University of Science and Technology, Tehran, Iran (2) Chemical Engineering Department ...
Research Interests: Materials Engineering, Materials Science, Chemistry, Catalysis, Scanning Electron Microscopy, and 14 moreNanomaterials, Porous Materials, Dehydrogenation, Nitrogen, Specific surface area, Surface Area, X ray diffraction, Thermal Stability, Fourier transform infrared spectroscopy, Thermogravimetric Analysis, NITRIC ACID, Hydrothermal treatment, Mesoporous Material, and temperature programmed reduction
ABSTRACT A new model for the excess Gibbs energy of hydrotrope solutions is presented. This model is based on the local composition model by Chen et al. Hydrotropes are usually organic salts that can increase the solubility of organic and... more
ABSTRACT A new model for the excess Gibbs energy of hydrotrope solutions is presented. This model is based on the local composition model by Chen et al. Hydrotropes are usually organic salts that can increase the solubility of organic and inorganic compounds in water. The proposed model has five adjustable parameters; one of them is related to long-range forces, and four of them are related to short-range forces. Long-range forces are modeled by the Pitzer-Debye-Huckel equation. However, in our model, the effect of the molecular solute on the dielectric constant of water has also been considered. Modeling of short-range forces is based on local composition concepts. The model parameters are obtained using experimental data for six hydrotropes with four solutes at different temperatures. The water solubility of molecular solutes in the presence of hydrotropes has been calculated for different systems. Accurate results are obtained. © 2005 American Institute of Chemical Engineers AIChE J, 2006
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The degradation of an industrial wastewater (Tire Cord factory) with low BOD5/COD ratio (0.1-0.2) was investigated using advanced oxidation processes (AOPs) (i.e. hydrogen peroxide, UV/H2O2, O3/H2O2 and UV/O3/H2O2 treatments). In order to... more
The degradation of an industrial wastewater (Tire Cord factory) with low BOD5/COD ratio (0.1-0.2) was investigated using advanced oxidation processes (AOPs) (i.e. hydrogen peroxide, UV/H2O2, O3/H2O2 and UV/O3/H2O2 treatments). In order to investigate the effects of influential variables on the process performance, four independent factors involving two numerical factors (initial H2O2 concentration and initial pH) and two categorical factors (ozonation and UV irradiation) were selected. The process was modeled and analyzed using response surface methodology (RSM). The region of exploration for the process was taken as the area enclosed by initial H2O2 concentration (0-20 mM) and initial pH (3-11) boundaries at three levels. For two categorical factors (ozonation and UV irradiation), the experiments were performed at two levels (with and without application of each factor). Two dependent parameters (TCOD removal and BOD5/COD ratio) were studied as the process responses. As a result, i...
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Fossil fuels are still primary resources of energy supply; however, they are undoubtedly responsible for most of the environmental pollutions. Over the last decades, renewable sources as clean alternative energies have received an... more
Fossil fuels are still primary resources of energy supply; however, they are undoubtedly responsible for most of the environmental pollutions. Over the last decades, renewable sources as clean alternative energies have received an increasing deal of attention due to the limitation of fossil fuel resources for reliable fulfillment of future energy demands and to address the environmental crises. Renewable energies predominately include solar, wind, biomass, hydrogen, and geothermal sources. Among these, biofuels derived from biomass are considered as the most promising candidate owing to a number of reasons such as direct conversion of biomass to liquid biofuels. Gases and liquid biofuels can be produced from biomass feedstock by three main approaches: thermochemical, biochemical, and microbiological technologies. Gasification, pyrolysis, liquefaction, hydrolysis, transesterification, and anaerobic digestion are main routes for biomass to biofuel conversion. In all biofuel production processes, developing the highest quality products with an optimized process (in terms of cost, energy consumption, etc.) is desirable which necessitates the exploitation of modern sciences such as nanotechnology. Among various aspects of nanotechnology, over the last several years, utilization of highly active nanocatalysts for biofuel production has been growing quickly. Recent research studies have mainly focused on developing efficient nanocatalysts for improving conversion, accessing milder operating conditions, and lowering the process cost of biofuel production to collectively try to industrialize these green fuels. This chapter summarizes an overview of various biofuel production processes and, moreover, strives to comprehensively discuss metal oxide nanocatalysts used for biofuel production.
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The solgel procedure was applied for the synthesis of nanocrystalline γ-alumina by means of the aluminum isopropoxide (AIP) precursor and a cationic surfactant in acidic medium. In this study, the response surface method (RSM) was... more
The solgel procedure was applied for the synthesis of nanocrystalline γ-alumina by means of the aluminum isopropoxide (AIP) precursor and a cationic surfactant in acidic medium. In this study, the response surface method (RSM) was applied for optimizing the most significant ...