• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.4
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• pp.259-269
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• 2013

Applicability of ammonium molybdophosphate/iron oxides-polyacrylonitrile (AMP/IO-PAN) composites on the removal of radionuclides in the radioactive wastewater generated from nuclear power plants was investigated. The composites were characterized using the following analytical techniques: X-ray diffraction (XRD), Fourior transform-infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), particle size analyzer (PSA), nitrogen adsorption-desorption and magnetic property measurement system (MPMS). 10wt% of AMP/IO-PAN composite has a saturation magnetization of 2.038 emu/g. Single-solute sorptions of Co, Sr and Cs onto 10wt% of AMP/IO-PAN composite were investigated. The maximum sorption capacities ($Q^0$) predicted by the Langmuir model on 10wt% of AMP/IO-PAN composite were 0.097, 0.086 and 0.66 mmol/g for Co, Sr and Cs, respectively. The maximum sorption capacities ($Q^0$) of Cs predicted by Langmuir model on 0, 10, 20 and 30wt% of AMP/IO-PAN composites were 0.702, 0.655, 0.602 and 0.559 mmol/g, respectively. The maximum sorption capacities ($Q^0$) of Cs decreased with increasing the iron oxide content in the AMP/IO-PAN composites.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.9
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• pp.542-547
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• 2017

This paper was to analyze the membrane characterization of hydrophilicity, surface morphology and membrane chemical anlysis of three commercial microfiltration/ultrafiltration membranes, and evaluate the filtration performance of a seawater to assess the availability for pretreatment of desalination process. From the results of contact angle, Mem-3, fabricated with polyacrylonitrile, was highly hydrophilic. It find out that Mem-3 has more anti-biofouling property. In Field emission scanning electron microscope (FESEM), Mem-1 (polyethylene) and Mem-2 (Polyvinylidenefluoride) showed the sponge-like shape and Mem-3 showed finger-like shape. Membrane chemical analysis by energy dispersive spectrometer (EDS) presented that Mem-2 was mostly fluoride and Mem-3 had s high ratio of N (32.47%) due to the nitrile group. The permeation flowrate per time on suction pressures using deionized water (D.I. water) tends that permeation rate of Mem-3 more increased when the pressure was increased compared to other membranes. From the results of turbidity and total suspended solids (TSS) removal, turbidity of permeate was 0.191 NTU to 0.406 NTU and TSS was 2.2 mg/L to 3.0 mg/L in all membranes, indicating that it was not suitable for the pretreatment of seawater desalination by short-term experiments.

• Journal of the Korean Wood Science and Technology
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• v.44 no.3
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• pp.406-414
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• 2016

The lignin-based carbon nanofiber reinforced epoxy composite has been prepared by immersing carbon nanofiber mat in epoxy resin solution in order to evaluate the physical and mechanical properties. The thermal and mechanical properties of the carbon nanofiber reinforced epoxy composite were analyzed using thermogravimetric analysis (TGA), differential scanning calorimeter (DSC) and tensile tester. It was found that the thermal properties of the carbon nanofiber reinforced epoxy composite improved, with its glass-transition temperature ($T_g$) increased from $90.7^{\circ}C$ ($T_g$ of epoxy resin itself) to $106.9^{\circ}C$. The tensile strengths of carbon nanofiber mats made from both lignin-g-PAN copolymer and PAN were 7.2 MPa and 9.4 MPa, respectively. The resulting tensile strength of lignin-based carbon nanofiber reinforced epoxy composite became 43.0 MPa, the six times higher than that of lignin-based carbon nanofiber mats. The carbon nanofibers were pulled out after the tensile test of the carbon nanofiber reinforced epoxy composite due to high tensile strength (478.8 MPa) of an individual carbon nanofiber itself as well as low interfacial adhesion between fibers and matrices, confirmed by the SEM analysis.

• Membrane Journal
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• v.11 no.2
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• pp.66-73
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• 2001

Ivlain objectives of this work arc to investigate basic fouling characteristics and emxts of backpulsing on the fouJing control in the free-end membrane module uo

• Journal of the Korean Electrochemical Society
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• v.5 no.3
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• pp.117-124
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• 2002

Poly(acrylonitrile)(PAN) solutions in dimethylformamide(DMF) were electrospun to prepare webs consisting of 400nm ultra-fine fibers. The webs were oxidatively stabilized, activated by steam and resulted to be activated carbon fibers(ACFs). The specific surface area was $800\~1230 m^2/g$, which showed a trend of a decrease of the surface area with an increase in activation temperature, showing opposite behavior to the other ACFs. The activation energy of the stabilized fibers for the steam activation was determined as 29.2 kJ/mol to be relatively low indicating the easier activation than that of other carbonized fibers. The ACF webs were characterized by pore size and specific surface uea which would be related to the specific capacitance of the electrical double layer capacitor (EDLC). The specific capacitances measured were 27 F/g, 25 F/g, 22 F/g at the respective activation temperature of $700^{circ}C,\;750^{\circ}C\;800^{\circ}C$, showing similar trend with the specific surface area i.e., the higher activation temperature was, the lower specific capacitance resulted.

• Journal of the Korean Electrochemical Society
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• v.2 no.2
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• pp.81-87
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• 1999

Poly-acrylonitrile (PAN) based carbon fibers were stabilized under various tensions in the presence of air at about $200^{\circ}C$ and sequentially carbonized under some different gas environments in the range of 700 to $1500^{\circ}C$. The prepared carbon fibers were used for rechargeable lithium ion battery anode to investigate preparation parameters effects on electrochemical characteristics. It was found that the tension during stabilization, carbonization temperature and gas atmospheres affect the carbon fiber properties such as conductivity, mechanical strength, surface morphology and diffusion coefficient of lithium ion, which are closely related to the on electrolchemical properties as well as the charge/discharge characteristics.

• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.191-195
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• 2018

In this study, the influence of microporous structures of activated carbon fibers (ACFs) on dimethyl methylphosphonate (DMMP) gas sensing properties as a nerve agent simulant was investigated. The pore structure was given to carbon fibers by chemical activation process, and an electrode was fabricated for gas sensors by using these fibers. The PAN based ACF electrode, which is an N-type semiconductor, received electrons from a reducing gas such as DMMP, and then electrical resistance of its electrode finally decreased because of the reduced density of electron holes. The sensitivity of the fabricated DMMP gas sensor increased from 1.7% to 5.1% as the micropore volume increased. It is attributed that as micropores were formed for adsorbing DMMP whose molecular size was 0.57 nm, electron transfer between DMMP and ACF was facilitated. In conclusion, it is considered that the appropriate pore structure control of ACFs plays an important role in fabricating the DMMP gas sensor with a high sensitivity.

• Journal of the Korean Ceramic Society
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• v.34 no.1
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• pp.56-62
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• 1997

The PAN (Polyacrylonitrile) based carbon fiber-ceramic composites (CFCC) were prepared from mixtures of short carbon fibers, phenolic resin and ceramic binder. The effects of carbonization temperature of a pre-cursor fiber, the stabilized PAN fiber, on the specific surface area and the bending strength of the activated CFCC were studied in this work. The precursor fiber was carbonized at 80$0^{\circ}C$ and 100$0^{\circ}C$, respectively. The CFCC were activated at 85$0^{\circ}C$ in carbon dioxide for 10~90 minutes. As the burn-off of the activated CFCC made of the precursor fiber carbonized at 80$0^{\circ}C$ was increased from 37% to 76%, the specific surface area in-creased from 493m2/g to 1090m2/g, and the bending strength decreased from 4.5MPa to 1.4MPa. These values were about two times larger than those of the activated CFCC of which precursor fiber was car-bonized at 100$0^{\circ}C$. The effects of carbonization temperature of a precursor fiber on the specific surface area and bending strength of the activated CCFC were explained by bonding force between carbon fiber and car-bonized phenolic resin as well as by relative shirnkage between carbon fiber and ceramic film.

• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.467-474
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• 2007

The palladium and gold nanoparticles containing PAN-based active carbon fiber (ACF) with a high specific surface area were prepared. Using the BET, TEM, FE-SEM, and XPS, their specific surface area and pore volume, pore structure, and the change in surface oxygen groups with time were analyzed and $SO_2$ adsorption performances were investigated. Because of the impregnating process, the micropore volume was mostly decreased from 95.5% to 30.5~43.7% compared with the total pore volume. And the change in surface oxygen groups with time was higher for the metal salt than the nanoparticles. Also, $SO_2$ breakthrough time of PAN-ACFs impregnated with Au nanoparticles and metal salts did not change compared with that of the non-impregnated PAN-ACF. But the PAN-ACF impregnated with Pd nanoparticles (100 ppm) showed good $SO_2$ adsorption performance as the breakthrough time of 880 sec. These results indicated that the $SO_2$ adsorption performance depended on the change in surface oxygen groups with time and the moderate impregnation of Pd nanoparticles on the PAN-ACF caused the increase in the $SO_2$ adsorption performance by a catalytic action.

• Applied Chemistry for Engineering
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• v.23 no.3
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• pp.313-319
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• 2012

In this work, the electroplating of copper was introduced on PAN-based carbon fibers for the enhancement of mechanical interfacial strength of carbon fibers-reinforced composites. The surface properties of carbon fibers were determined by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and contact angle measurements. Its mechanical interfacial properties of the composites were studied by interlaminar shear strength (ILSS) and critical stress intensity factor ($K_{IC}$). From the results, it was found that the mechanical interfacial properties of Cu-plated carbon fibers-reinforced composites (Cu-CFRPs) enhanced with increasing the Cu plating time, Cu content and COOH group up to Cu-CFRP-30. However, the mechanical interfacial properties of the Cu-CFRPs decreased dramatically in the excessively Cu-plated CFRPs sample. In conclusion, the presence of Cu particles on carbon fiber surfaces can be a key factor to determine the mechanical interfacial properties of the Cu-CFRPs, but the excessive Cu content can lead the failure due to the interfacial separation between fibers and matrices in this system.