Sharif Digital Repository

Due to the high activity of Au nanoparticles (NPs) for various reactions, many researchers have tried to develop heterogeneous catalysts in order to prevent irreversible agglomeration of Au NPs. Herein, magnetic graphene oxide modified with polyaniline (PANI) was used as a support for Au NPs that brings together advantages including: uniform dispersal of the catalyst in water,alarge surface area related to the graphene oxide; easy electron transfer in chemical reactions and good attachment of Au NPs to the support associated with PANI; and finally facile recovery in the presence of a magnetic field. Catalytic reduction of different analytes (Congo red, methylene blue, rhodamine B and 4-nitro... 

For the first time the new 32-membered macrocyclic dinuclear palladium complex of two aza-crown macrocycles, bearing two pyridine arms, Pd2L2Cl4 was synthesized and characterized by elemental analysis, IR, NMR spectroscopy and single crystal X-ray diffraction methods. Pd2L2Cl4 was investigated as a moisture/air-stable catalyst for Sonogashira cross-coupling reaction in the absence of copper and phosphine ligand in DMSO. Thermal stability, possible occurrence of tandem reactions, promoted catalytic performance as well as synergistic effects are of advantageous features of Pd2L2Cl4. By employing Taguchi method, optimum conditions (110 °C, 6 h, KOAc, 2 mol% cat.) were determined. Moreover, the... 

Breast Cancer (BRCA) is the most common threat in women worldwide. Increasing death rate of diagnosed cases is the main leading cause of designing specific genosensors for BRCA − related cancer detection. In the present study, an ultrasensitive label − free electrochemical DNA (E − DNA) sensor based on conducting polymer/reduced graphene − oxide platform has been developed for the detection of BRCA1 gene. An electrochemical method was applied as a simple and controllable technique for the electrochemical reduction of graphene oxide and also, electro − polymerization of pyrrole − 3 − carboxylic acid monomer. The results of the present work show that the polymer − coated reduced graphene −... 

A highly water stable metal-organic framework (MOF) based on zirconium, i.e. UiO-66, was synthesized and then employed to adsorptive removal of an anionic dye, methyl orange (MO), and a cationic dye, methylene blue (MB), from aqueous solution. In this work, for the first time, the long term stability of UiO-66 in water was investigated for 12 months. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and N2 adsorption/desorption analysis were employed to monitor the textural alteration of UiO-66 during water aging. The results indicated that the structure of UiO-66 was mostly retained and its adsorption capacity toward dyes exhibited minor loss after long term water... 

In the present study, dual layers mixed matrix membranes (MMMs) were prepared by incorporating aminated-Fe3O4 nanoparticles into the chitosan/polyvinyl alcohol nanofibers over the polyethersulfone (PES) membrane for the removal of Cr(VI) and Pb(II) ions in batch adsorption and membrane processes. The synthesized aminated-Fe3O4 nanoparticles were characterized using XRD, FESEM and FTIR analysis. The morphology and roughness of membranes were determined using SEM, TEM and AFM analysis. The effect of adsorption operating parameters such as pH (2–7), contact time (0–60 min), initial concentration of metal ions (20–1000 mgL−1) and temperature (30–50 °C) on the Cr(VI) and Pb(II) ions sorption was... 

A magnetic nanocomposite was prepared by entrapment of Fe3O4 nanoparticles into the cross-linked ionic liquid/epoxy type polymer. The resulting support was used for covalent immobilization of cellulase through the reaction with epoxy groups. The ionic surface of the support improved the adsorption of enzyme, and a large amount of enzyme (106.1 mg/g) was loaded onto the support surface. The effect of the presence of ionic monomer and covalent binding of enzyme was also investigated. The structure of support was characterized by various instruments such as FT-IR, TGA, VSM, XRD, TEM, SEM, and DLS. The activity and stability of immobilized cellulase were investigated in the prepared support. The... 

Large Multi-Processor Systems-on-Chip use Networks-on-Chip with a high degree of reusability and scalability for message communication. Therefore, network infrastructure is a crucial element affecting the overall system performance. On the other hand, technology improvements may lead to much energy consumption in micro-routers of an on-chip network. This necessitates an exhaustive analysis of NoCs for future designs. This paper presents a comprehensive analytical model to predict message latency for different data flows traversing across the network. This model considers channel buffers of multiple flits which were not previously studied in NoC context. Also, architectural descriptions of... 

The catalytic activity of a mixture of ZnCl2: AlCl3 supported on silica gel was evaluated for the alkylation of phenols with benzyl alcohol, tret-butyl alcohol and styrene under microwave irradiation and solvent-free conditions. The catalyst preparation method, its characterization and reusability, were reported. The effect of the phenol to benzyl alcohol ratio and the time of reaction on the phenol conversion and distribution of products was investigated. A conversion percentage up to 97% was achieved when hydroquinone was used. A selective ortho- directed alkylation for phenol, α-naphthol and β-naphthol was observed. © Sharif University of Technology, December 2009  

The chitosan-grafted-poly(N-vinylcaprolactam) (chitosan-g-PNVCL) nanofibers were synthesized via electrospinning method. ZIF-8 metal-organic frameworks nanoparticles were incorporated into the nanofibers for adsorption of Cr(VI), As(V) and phenol from water. The BET, FTIR, XRD and SEM analysis were carrfried out to obtain the characteristics of nanofibers. The optimum parameters of ZIF-8 content, pH, contact time, adsorbent dosage, and initial concentration of adsorbates on the Cr(VI), As(V) and phenol removal were studied. The reusability of synthesized nanofibers for five sorption-desorption cycles was also examined. The maximum experimental adsorption capacity of the... 

The nanocomposite of zero-valent iron and delafossite CuFeO2 supported on reduced graphene oxide was synthesized for the first time to evaluate its performance as the heterogeneous catalyst toward electro-Fenton (EF) removal of catechol. X-ray diffraction, Fourier transform-infrared, scanning electron microscopy and Brunauer–Emmett–Teller (BET) were used to characterize the nanocomposite. It was found that the rhombohedral structure of CuFeO2 remained stable during the nanocomposite preparation. The BET surface area of the nanocomposite increased about 102 times in comparison with bare CuFeO2. The influence of the operating parameters was investigated. The optimum operating conditions were... 

Vanadium supported on spinel cobalt ferrite nanoparticles was synthesized and characterized using Fourier transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray analysis and transmission electron microscopy. For the first time, the prepared material was used for the catalytic degradation of methylene blue as an organic dye in the presence of hydrogen peroxide as a green oxidant and NaHCO3 as a co-reagent at room temperature. The dependency of removal percentage on various parameters such as amount of catalyst, pH, reaction time and temperature and the effect of radical scavenging agents were studied. Finally, recoverability and reusability of the vanadium supported on... 

In this study, graphene oxide (GO) was synthesized via modified Hummer's method and exploited as an ideal enzyme immobilization support due to its exclusive chemical and structural features. Then, laccase from genetically modified Aspergillus was covalently immobilized onto GO (nanobiocatalyst). Enzymatic characterization of the nanobiocatalyst exhibited promising results: laccase loading of 156.5 mg g−1 and immobilization yield of 64.6% at laccase concentration of 0.9 mg/ mL. Further employment of various structural characterization techniques including Fourier Transform Infrared Spectroscopy (FTIR), X-ray Powder Diffraction (XRD), Scanning Electron Microscopy (SEM), Thermo-Gravimetric... 

The design and development of efficient approaches for water–oil separation have had widespread interest. Most previously introduced techniques and materials used for development of the successful separation of oily wastewater could not answer all the desired demands, such as being efficient and environmentally and economically friendly. Therefore, in seeking a novel method capable of answering these expectations, surfaces with special wettability were introduced. A novel, reusable, and recyclable superhydrophilic and superoleophobic poly(Vsim-Vim)@PFOA@SiO2 nanocomposite-coated stainless steel mesh was synthesized through a facile preparation process. Since the most important factors of... 

A highly selective and effective catalyst and photocatalyst based on Ag, Pt, AgPt nanoparticles (NPs) on the surface of γ-Fe2O3 /t-ZrO2 nanocomposite which was derived from Fe-metal organic framework (Fe-MIL-88A) and Zr-metal organic framework (Zr-UiO-66) was developed. A green synthesis method was used for synthesis of binary nanocomposite (M = Ag, Pt, and Ag@Pt NPs)@γ-Fe2O3/t-ZrO2 and a new composite of γ-Fe2O3, t-ZrO2 structures which was made up by annealing under a nitrogen gas flow. The catalytic potential of the as-synthesized samples were considered toward the reduction of 4-nitrophenol (4-Nip) to 4-aminophenol (4-Amp) by NaBH4 solution at 25 °C and different reaction times. For the... 

The oxidation-precipitation method was used for the synthesis of Fe3O4/AC. The characterization of the catalyst was accomplished by XRD, FT-IR, FE-SEM, BET, and VSM techniques. The obtained results indicated that magnetite nanoparticles were successfully prepared with cubic spinel structures and uniform distribution on the surface of activated carbon by the oxidation-precipitation method. The effect of operating parameters was evaluated to determine the optimum operating condition for the electro-Fenton (EF) removal of catechol as a phenolic pollutant model. At the optimum operating conditions (pH 3, Fe3O4/AC: 0.9 g L−1, Catechol: 8.0 × 10−4mol L−1 at I: 120 mA), the catechol and COD removal... 

The present article describes the synthesis of a new magnetic polyacrylonitrile-based Pd catalyst involving polyacrylonitrile modified via 2-aminopyridine as an efficient support to immobilize Pd nanoparticles. The simple reusability, easy separation and high stability of this Pd complex make it an excellent candidate to generate a C–O bond via Ph-X activation which is a really important subject in achieving biologically active compounds. It is worth to note access to good and high yields as well as broad substrate scope have resulted from superior reactivity of this catalyst complex. Furthermore, the structure of the magnetic polyacrylonitrile-based heterogeneous catalyst was characterized... 

The nanofibers prepared by electrospinning process have high potential for the removal of toxic matters from wastewaters. In the present study, the titanium dioxide and titanium dioxide/zinc oxide (TiO2/ZnO) nanofibers prepared by electrospinning technique were coated on the sewage sludge carbon (SSC) surface for adsorption of Ni(II), Cu(II), and COD from aqueous solutions and industrial wastewaters of Iran. The synthesized adsorbents were characterized using XRD, SEM and EDX analysis. The effect of adsorbent type, pH, adsorbent dosage, contact time and initial concentrations of Ni(II), Cu(II) and COD on the adsorption capacity of synthesized SSC/TiO2 and SSC/TiO2/ZnO nanofibrous adsorbents... 

In this work, a facile ionic liquid-mediated method was utilized to fabricate an efficient photocatalyst for environmental remediation. The eco-friendly aspect of the treatment was explored through an in-vivo toxicity bioassay. ZnO particles, prepared by a combined solid state-pyrolysis method, were coated by 1-methyl-3-(oxiran-2ylmethyl)-1H-imidazolium-3-chloride ([MOYI]Cl) ionic liquid. Then, Ag/AgCl species were grown on the surface to make a heterojunction system leading to efficient charge separation and light absorption extension to the visible domain. The products were characterized by XRD, FTIR, SEM, EDX, DRS, BET, and PL analysis. Photocatalytic performance of the nanostructures was... 

The design and development of efficient approaches for water–oil separation have had widespread interest. Most previously introduced techniques and materials used for development of the successful separation of oily wastewater could not answer all the desired demands, such as being efficient and environmentally and economically friendly. Therefore, in seeking a novel method capable of answering these expectations, surfaces with special wettability were introduced. A novel, reusable, and recyclable superhydrophilic and superoleophobic poly(Vsim-Vim)@PFOA@SiO2 nanocomposite-coated stainless steel mesh was synthesized through a facile preparation process. Since the most important factors of... 

The nanofibers prepared by electrospinning process have high potential for the removal of toxic matters from wastewaters. In the present study, the titanium dioxide and titanium dioxide/zinc oxide (TiO2/ZnO) nanofibers prepared by electrospinning technique were coated on the sewage sludge carbon (SSC) surface for adsorption of Ni(II), Cu(II), and COD from aqueous solutions and industrial wastewaters of Iran. The synthesized adsorbents were characterized using XRD, SEM and EDX analysis. The effect of adsorbent type, pH, adsorbent dosage, contact time and initial concentrations of Ni(II), Cu(II) and COD on the adsorption capacity of synthesized SSC/TiO2 and SSC/TiO2/ZnO nanofibrous adsorbents...