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Influence of oxyfluorination on activated carbon nanofibers for CO<SUB>2</SUB> storage
Byong-Chol Bai,Jong-Gu Kim,Ji-Sun Im,Sang-Chul Jung,Young-Seak Lee 한국탄소학회 2011 Carbon Letters Vol.12 No.4
The oxyfluorination effects of activated carbon nanofibers (OFACFs) were investigated for CO2 storage. Electrospun CFs were prepared from a polyacrylonitrile/N,N-dimethylformamide solution via electrospinning and heat treatment. The electrospun CFs were chemically activated in order to generate the pore structure, and then oxyfluorination was used to modify the surface. The samples were labeled CF (electrospun CF), ACF (activated CF), OFACF-1 (O2:F2 = 7:3), OFACF-2 (O2:F2 = 5:5) and OFACF-3 (O2:F2 = 3:7). The functional group of OFACFs was investigated using X-ray photoelectron spectroscopy analysis. The C-F bonds formed on surface of ACFs. The intensities of the C-O peaks increased after oxyfluorination and increased the oxygen content in the reaction gas. The specific surface area, pore volume and pore size of OFACFs were calculated by the Brunauer-Emmett-Teller and density functional theory equation. Through the N2 adsorption isotherm, the specific surface area and pore volume slightly decreased as a result of oxyfluorination treatment. Nevertheless, the CO2 adsorption efficiency of oxyfluorinated ACF improved around 16 wt% due to the semi-ionic interaction effect of surface modificated oxygen functional groups and CO2 molecules.
Thermal Properties of Asphalt Mixtures Modified with Conductive Fillers
Bai, Byong Chol,Park, Dae-Wook,Vo, Hai Viet,Dessouky, Samer,Im, Ji Sun Hindawi Limited 2015 Journal of nanomaterials Vol.2015 No.-
<P>This paper investigates the thermal properties of asphalt mixtures modified with conductive fillers used for snow melting and solar harvesting pavements. Two different mixing processes were adopted to mold asphalt mixtures, dry- and wet-mixing, and two conductive fillers were used in this study, graphite and carbon black. The thermal conductivity was compared to investigate the effects of asphalt mixture preparing methods, the quantity, and the distribution of conductive filler on thermal properties. The combination of conductive filler with carbon fiber in asphalt mixture was evaluated. Also, rheological properties of modified asphalt binders with conductive fillers were measured using dynamic shear rheometer and bending beam rheometer at grade-specific temperatures. Based on rheological testing, the conductive fillers improve rutting resistance and decrease thermal cracking resistance. Thermal testing indicated that graphite and carbon black improve the thermal properties of asphalt mixes and the combined conductive fillers are more effective than the single filler.</P>
Blending effect of pyrolyzed fuel oil and coal tar in pitch production for artificial graphite
Byong Chol Bai,Jong Gu Kim,Ji Hong Kim,Chul Wee Lee,Young-Seak Lee,Ji Sun Im 한국탄소학회 2018 Carbon Letters Vol.25 No.-
Pyrolyzed fuel oil (PFO) and coal tar was blended in the feedstock to produce pitch via thermal reaction. The blended feedstock and produced pitch were characterized to investigate the effect of the blending ratio. In the feedstock analysis, coal tar exhibited a distinct distribution in its boiling point related to the number of aromatic rings and showed higher Conradson carbon residue and aromaticity values of 26.6% and 0.67%, respectively, compared with PFO. The pitch yield changed with the blending ratio, while the softening point of the produced pitch was determined by the PFO ratio in the blends. On the other hand, the carbon yield increased with increasing coal tar ratio in the blends. This phenomenon indicated that the formation of aliphatic bridges in PFO may occur during the thermal reaction, resulting in an increased softening point. In addition, it was confirmed that the molecular weight distribution of the produced pitch was associated with the predominant feedstock in the blend.
Byong Chol Bai,Ji Sun Im,Young-Seak Lee 한국탄소학회 2017 Carbon Letters Vol.23 No.-
In gas adsorption processes, activated carbon fibers (ACFs) are used for the adsorption of the harmful gases that are generated by coal or oil combustion, and they have been widely studied [1,2]. ACFs have been used for harmful gas removal because of their specific surface area, micropores, reproducibility, safety, and processing ability, which are beneficial properties for a wide range of applications [3,4].
Byong-Chol Bai,Jong-Gu Kim,Mehraj-Ud-Din Naik,Ji-Sun Im,Young-Seak Lee 한국탄소학회 2011 Carbon Letters Vol.12 No.3
Polyacrylonitrile-based carbon nanofibers (CNFs) containing Ti and Mn were prepared by electrospinning. The effect of metal content on the hydrogen storage capacity of the nanofibers was evaluated. The nanofibers containing Ti and Mn exhibited maximum hydrogen adsorption capacities of 1.6 and 1.1 wt%, respectively, at 303 K and 9 MPa. Toward the development of an improved hydrogen storage system, the optimum conditions for the production of metalized CNFs were investigated by characterizing the specific surface areas, pore volumes, sizes, and shapes of the fibers. According to the results of Brunauer-Emmett-Teller analysis, the activation of the CNFs using potassium hydroxide resulted in a large pore volume and specific surface area in the samples. This is attributable to the optimized pore structure of the metal-containing polyacrylonitrile-based electrospun CNFs, which may provide better sites for hydrogen adsorption than do current adsorbates.
Effect of oxyfluorination on activated electrospun carbon nanofibers for CO<sub>2</sub> storage
배병철(Bai, Byong Chol),김종구(Kim, Jong Gu),임지선(Im, Ji Sun),이영석(Lee, Young-Seak) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.05
The oxyfluorination effects of electrospun carbon nanofibers (OFACFs) were investigated for CO₂ storage. Carbon nanofibers were prepared form poly acrylonitrile / N,N-dimethylformamide solution through electrospinning method and heat treatment. Chemical activation of carbon nanofibers were carried out in order to improve the pore structure. And the surface modification of activated carbon nanofibers was conducted by oxyfluorination to improve the CO₂ storage on effect of introduced functional groups. The samples were labeled CF (electrospun carbon nanofiber), ACF (activated carbon nanofibers), OFACF-1 (F₂:O₂ = 3:7), OFACF-2 (F₂:O₂ = 5:5) and OFACF-3 (F₂:O₂ = 7:3). The functional group of OFACFs was investigated by x-ray photoelectron spectroscopy analysis. The specific surface area, pore volume and pore size of OFACFs were calculated and pore shape was estimated by the BET equation. Through the adsorption isotherm, the specific surface area and pore volume significantly decreased by oxyfluorination.
Flame retardant epoxy complex produced by addition of montmorillonite and carbon nanotube
Sung Kyu Lee,Byong Chol Bai,임지선,Se Jin In,이영석 한국공업화학회 2010 Journal of Industrial and Engineering Chemistry Vol.16 No.6
Flame retardant additives of montmorillonite (MMT) and multi-walled carbon nanotube (MWCNT) were embedded in epoxy resin to improve the resin’s resistance to oxidation. The MWCNTs reduced the degradation rate of the epoxy complex and increased the char yield, and also increased the limiting oxygen index in a first order relationship with char yield. MMT acted as an energy storage medium to hinder thermal transfer within the epoxy complex. The thermal activation energy increased upon addition ofMMT/MWCNT. Addition ofMMT andMWCNT significantly improved the flame retardant and anti-oxidation properties of the epoxy complex. 2010 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.