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2009, Vol.10, No.4

  • 1.

    Preparation and Characterization of KOH-Activated Carbons Developed from Petroleum Coke

    S. A. Sayed Ahmed | Reham M. M. Abo El-enin | Th. El-Nabarawy | 2009, 10(4) | pp.293~299 | number of Cited : 3
    Abstract
    Potassium hydroxide activated carbons were prepared from Egyptian petroleum cokes with different KOH/coke ratios and at different activation temperatures and times. The textural properties were determined by adsorption of nitrogen at −196oC. The adsorption of iodine and methylene blue was also investigated at 30oC. The surface area and the non-micropore volume increased whereas the micropore volume decreased with the increase of the ratio KOH/coke. Also the surface area and porosity increased with the rise of activation temperature from 500 to 800oC. Textural parameter considerably increased with the increase of activation time from 1 to 3 h. Further increasing of activation time from 3 to 4 h was associated with a less pronounced increase in textural parameters. The adsorption of iodine shows the same trend of surface area and porosity change exhibited by nitrogen adsorption, with KOH/coke ratio and temperature of activation. Adsorption of methylene blue follows pseudo-first-order kinetics and its equilibrium adsorption follows Langmuir and D-R models.
  • 2.

    Thermal Emissivity of a Nuclear Graphite as a Function of Its Oxidation Degree (2) - Effect of Surface Structural Changes -

    서승국 | Eung-Seon Kim | Se-Hwan Chi and 3other persons | 2009, 10(4) | pp.300~304 | number of Cited : 4
    Abstract
    Thermal emissivity of nuclear graphite was measured with its oxidation degree. Commercial nuclear graphites (IG-110, PECA, IG-430, and NBG-18) have been used as samples. Concave on graphites surface increased as its oxidation degree increased, and R value (Id/Ig) of the graphites decreased as the oxidation degree increased. The thermal emissivity increased depending on the decrease of the R (Id/Ig) value through Raman spectroscopy analysis. It was determined that the thermal emissivity was influenced by the crystallinity of the nuclear graphite.
  • 3.

    Removal of Toxic Pollutants from Aqueous Solutions by Adsorption onto Organo-kaolin

    S. A. Sayed Ahmed | 2009, 10(4) | pp.305~313 | number of Cited : 1
    Abstract
    In this study, the adsorption of toxic pollutants onto cetyltrimethylammonium kaolin (CTAB-Kaolin) is investigated. The organo-kaolin is synthesized by exchanging cetyltrimethylammonium cations (CTAB) with inorganic ions on the surface of kaolin. The chemical analysis, the structural and textural properties of kaolin and CTAB-kaolin were investigated using elemental analysis, FTIR, SEM and adsorption of nitrogen at −196oC. The kinetic adsorption and adsorption capacity of the organo-kaolin towards o-xylene, phenol and Cu(II) ion from aqueous solution was investigated. The kinetic adsorption data of o-xylene, phenol and Cu(II) are in agreement with a second order model. The equilibrium adsorption data were found to fit Langmuir equation. The uptake of o-xylene and phenol from their aqueous solution by kaolin, CTAB-kaolin and activated carbon proceed via physisorption. The removal of Cu(II) ion from water depends on the surface properties of the adsorbent. Onto kaolin, the Cu(II) ions are adsorbed through cation exchange with Na+. For CTAB-kaolin, Cu(II) ions are mainly adsorbed via electrostatic attraction with the counter ions in the electric double layer (Br−), via ion pairing, Cu(II) ions removal by the activated carbon is probably related to the carbon-oxygen groups particularly those of acid type. The adsorption capacities of CTAB-kaolin for the investigated adsorbates are considerably higher compared with those of unmodified kaolin. However, the adsorption capacities of the activated carbons are by far higher than those determined for CTAB-kaolin.
  • 4.

    X-ray Photoelectron Spectroscopic Analysis of Modified MWCNT and Dynamic Mechanical Properties of E-beam Cured Epoxy Resins with the MWCNT

    Lee, Young-Seak | Im Ji Sun | Seok-Min Yun and 3other persons | 2009, 10(4) | pp.314~319 | number of Cited : 7
    Abstract
    The surface treatment effects of reinforcement filler were investigated based on the dynamic mechanical properties of mutiwalledcarbon nanotubes (MWCNTs)/epoxy composites. The as-received MWCNTs(R-MWCNTs) were chemically modifiedby direct oxyfluorination method to improve the dispersibility and adhesiveness with epoxy resins in composite system. Inorder to investigate the induced functional groups on MWCNTs during oxyfluorination, X-ray photoelectron spectroscopywas used. The thermo-mechanical property of MWCNTs/epoxy composite was also measured based on effects ofoxyfluorination treatment of MWCNTs. The storage modulus of MWCNTs/epoxy composite was enhanced about 1.27 timesthrough oxyfluorination of MWCNTs fillers at 25oC. The storage modulus of oxyfluorinated MWCNTs (OF73-MWCNTs)reinforced epoxy composite was much higher than that of R-MWCNTs/epoxy composite. It revealed that oxygen content ledto the efficient carbon-fluorine covalent bonding during oxyfluorination. These functional groups on surface modifiedMWCNTs induced by oxyfluorination strikingly made an important role for the reinforced epoxy composite.
  • 5.

    Effect of CNT Diameter on Physical Properties of Styrene-Butadiene Rubber Nanocomposites

    Young Soo Park | Mongyoung Huh | Kang Shin Jae and 2other persons | 2009, 10(4) | pp.320~324 | number of Cited : 0
    Abstract
    We investigated the effect of diameter and content of carbon nanotubes (CNTs) on the physical properties of styrenebutadiene rubber (SBR)/CNTs nanocomposites. CNTs-reinforced SBR nanocomposites were prepared by the melt mixing process. CNTs with different diameters were synthesized by the chemical vapor deposition method (CVD). In this work, the mechanical property and other physical properties of SBR/CNTS nanocomposites were discussed as a function of the content and diameter of CNTs.
  • 6.

    Sonochemical Synthesis of Closed [5,6]-bridged Aziridino[70]fullerene Derivative and Self-assembled Multilayer Films

    윤신숙 | 황성호 | Sung Kyu Hong and 2other persons | 2009, 10(4) | pp.325~328 | number of Cited : 0
    Abstract
    This cycloaddition of [70]fullerene with methyl azidoacetate in benzene under ultrasonic irradiated condition afforded the closed [5,6]-bridged aziridino[70]fullerene derivative, which was unusual product of cycloaddition to the 5,6-junction of fullerene. Its structure was determined by FAB-MS, UV-vis, 1H- and 13C-NMR spectral data. The closed [5,6]-bridged aziridino[70]fullerene-functionalized gold nanoparticle films were self-assembled using the layer-by-layer method on the reactive of glass slides functionalized with 3-mercaptopropyltrimethoxysilane. The functionalized glass slides were alternately soaked in the solution containing closed the [5,6]-bridged aziridino[70]fullerene and 4-aminothiophenoxide/hexanethiolateprotected gold nanoparticles. The closed [5,6]-bridged aziridino[70]fullerene-functionalized gold nanoparticle films have grown up to 5 layers depending on the immersion time. The self-assembled nanoparticle multilayer films were characterized using UV-vis spectroscopy showed that the surface plasmon band of gold at 527 nm gradually became more evident as successive layers were added to the films.
  • 7.

    Preparation and Characterization of Poly(amide imide)-based Carbon Nanofibers/Epoxy Nanocomposites

    서민강 | Kyeong-Eun Choi | Sang-Hee Park and 2other persons | 2009, 10(4) | pp.329~334 | number of Cited : 3
    Abstract
    In this work, the effect of carbon nanofibers (CNFs) addition on physicochemical characteristics of CNFs-reinforced epoxy matrix nanocomposites was studied. Poly(amide imide) solutions in dimethylformamide were electrospun into webs consisting of 250±50 nm fibers which were used to produce CNFs through stabilization and carbonization processes. As a result, the CNFs with average diameter of 200 ±20 nm were obtained after carbonization process. The nanocomposites with CNFs showed an improvement of thermal stability parameters and fracture toughness factors, compared to those of the specimen without CNFs, which could be probably attributed to the higher specific surface area and larger aspect ratio of CNFs, resulting in improving the mechanical interlocking in the nanocomposites. Also, the applied external loading can effectively transfer to CNFs because strong interactions are resulted between the epoxy matrix and the CNFs.
  • 8.

    Electrical and Mechanical Properties of Graphite Nanosheet/Carbon Nanotubes-filled Epoxy Nanocomposites

    Ki-Seok Kim | Kyungeun Choi | PARK SOOJIN | 2009, 10(4) | pp.335~338 | number of Cited : 3
    Abstract
    In this work, the effect of co-carbon fillers on the electrical and mechanical properties of epoxy nanocomposites was investigated. The graphite nanosheets (GNs) and multi-walled carbon nanotubes (MWNTs) were used as co-carbon fillers. The results showed that the electrical conductivity of the epoxy nanocomposites showed a considerable increase upon an addition of MWNTs when GNs were fixed at 2 wt.%. This indicated that low content GNs formed the bulk conductive network and then MWNTs added were intercalated between the GN layers, resulted in the formation of additional conductive pathway. Furthermore, the flexural strength of the epoxy nanocomposites was enhanced with increasing the MWNT content. It was probably attributed to the flexible MWNTs compared with rigid GNs, resulted in the enhancement of the mechanical properties.
  • 9.

    Preparation and Characterization of Activated Henequen Fiber

    Jong Seon Jeong | Lee, Young-Seak | Xiao Ping Yang and 1other persons | 2009, 10(4) | pp.339~344 | number of Cited : 0
    Abstract
    Henequen fiber was air-stabilized, carbonized, and steam-activated to obtain high surface area activated henequen fiber (AHF). Thermal behavior of henequen fibers has been studied by TGA. The structural morphology and characteristics were observed by SEM and BET surface area measurement. The yield of AHF from natural henequen was in the range of 20~25 wt%. Mesopores (2~2.5 nm) were developed on the AHF as the activation temperature was raised up to 700oC, and the band of mesopore size distribution moved to 15~30 nm when the activation were carried out at 900oC for 30 min. The specific surface area and the total pore volume were about 1394 m2/g and 1.30 cm3/g, respectively at this activation conditions.