• Journal of the Korean Wood Science and Technology
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• v.36 no.4
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• pp.52-57
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• 2008

In this study, the effects of carbonization temperature on the physico-chemical properties of porous wood charcoal are studied by FT-IR and Raman spectroscopies. IR studies showed that cellulose and hemicellulose are mostly decomposed in the precarbonization stage at $500^{\circ}C$, while the decomposition reaction of relatively more stable lignin lasts up to $700^{\circ}C$. Above $900^{\circ}C$, the peak at $1575cm^{-1}$ disappears and a new peak at $1630cm^{-1}$, which seems to be related to the new carbon deposit phase, is evolved. The results of Raman studies, which show the red-shift of D-band and the increase in the relative intensity of D- to G-band, indicate that the size of the crystalline becomes smaller with increasing the carbonization temperature.

• Journal of the Korean Ceramic Society
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• v.55 no.2
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• pp.160-165
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• 2018

This paper investigates the reaction rate of $CO_2$ storing carbonation hybrid reaction by comparing the behavior of carbonation between $Ca(OH)_2$ and fly ash with that of CFBC (Circulating Fluidized Bed Combustion) containing plenty of Free-CaO. Because fly ash with CFBC contains a lot of unreacted CaO, it cannot be used as a raw material for concrete admixtures and its usages are limited. To reuse such material, we stabilized unreacted CaO by carbonation and investigated the carbonation rate. We used a pH meter and a thermometer to check the rate of the carbonization. Also, we set the contents of fly ash with CFBC, $Ca(OH)_2$, flow and fluid of $CO_2$, respectively, to 100 g, 50 g, 100 ~ 1000 cc/min and 400 g based on the content of Free-CaO. We used carbonated water instead of water, and added an alkaline activator to promote the carbonation rate. As a result, the addition of the alkaline activator and carbonated water promoted the rate of carbonation via a hybrid reaction.

• Analytical Science and Technology
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• v.28 no.1
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• pp.40-46
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• 2015

Hydrochar has been generated from food waste via hydrothermal carbonization (HTC) reaction. As a solid product of HTC reaction, hydrochar has a great potential as an adsorbent of pollutants from the various media. The surface area and pore volumes are very important parameters to be served as an adsorbent. It requires an expensive equipment and consumes time to measure those parameter. Therefore, titration methods including iodine and methylene blue adsorption were evaluated to be correlated with that of BET analysis. Even though the absolute values of the computed surface area and pore volumes were not able to be matched directly, the patterns of change were successfully correlated. Among the reaction conditions, the reaction time and temperature at $230^{\circ}C$ for 4 h was determined as an optimization condition, which confirmed by titration method and BET analysis. Titration method for surface area and pore volumes computed by combination of iodine and methylene blue adsorbing values would be a simple and fast way of determining the optimization condition for hydrochar as an adsorbent produced by HTC reaction.

• Carbon letters
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• v.10 no.3
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• pp.217-220
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• 2009

In this study, porous electrospun carbon fibers were prepared by electrospinning with PAN and $MgCl_2$, as a MgO precursor. MgO was selected as a substrate because of its chemical and thermal stability, no reaction with carbon, and ease of removal after carbonization by dissolving out in acidic solutions. $MgCl_2$ was mixed with polyacrylonitrile (PAN) solution as a precursor of MgO with various weight ratios of $MgCl_2$/PAN. The average diameter of porous electrospun carbon fibers increased from 1.3 to 3 ${\mu}m$, as the $MgCl_2$ to PAN weight ratio increased. During the stabilization step, $MgCl_2$ was hydrolyzed to MgOHCl by heat treatment. At elevated temperature of 823 K for carbonization step, MgOHCl was decomposed to MgO. Specific surface area and pore structure of prepared electrospun carbon fibers were decided by weight ratio of $MgCl_2$/PAN. The amount of hydrogen storage increased with increase of specific surface area and micropore volume of prepared electrospun carbon fibers.

• Journal of the Korean Applied Science and Technology
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• v.15 no.1
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• pp.79-90
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• 1998

One of the objectives of this study were to develop a process for manufacturing activated carbons from agricultural by-products(rice shells and saw dust) and another is to measure the iodine number, ash content and removal ratio of COD. The other is to compare those values with those of commercialized activated carbons. Agricultural by-products based activated carbons were manufactured through the steam-reaction method. A rotary kiln type furnace was used for both carbonization and activation. The optimum operating temperatures for carbonization and activation were $650^{\circ}C$ and $900^{\circ}C$, respectively. For the activated carbons produced under these conditions, the iodine number was 1,127mg/g. Especially, removal efficiency of COD was 61.5% for 40mg/L of wastewater and 30% for 150mg/L of SLS(Sodium Lauryl Sulfate).

• Analytical Science and Technology
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• v.30 no.4
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• pp.174-181
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• 2017

Bio-liquid is a liquid by-product of the hydrothermal carbonization (HTC) reaction, converting wet biomass into solid hydrochar, bio-liquid, and bio-gas. Since bio-liquid contains various compounds, it requires efficient sampling method to extract the target compounds from bio-liquid. In this research, fatty acid methyl ester (FAME) in bio-liquid was extracted based on hollow fiber supported liquid phase microextraction (HF-LPME) and determined by Gas Chromatography-Flame Ionization Detector (GC-FID) and Gas Chromatography/Mass Spectrometry (GC/MS). The well-known major components of biodiesel, including methyl myristate, palmitate, methyl palmitoleate, methyl stearate, methyl oleate, and methyl linoleate had been selected as standard materials for FAME analysis using HF-LPME. Physicochemical properties of bio-liquid was measured that the acidity was 3.30 (${\pm}0.01$) and the moisture content was 100.84 (${\pm}3.02$)%. The optimization of HF-LPME method had been investigated by varying the experimental parameters such as extraction solvent, extraction time, stirring speed, and the length of HF at the fixed concentration of NaCl salt. As a result, optimal conditions of HF-LPME for FAMEs were; n-octanol for extraction solvent, 30 min for extraction time, 1200 rpm for stirring speed, 20 mm for the HF length, and 0.5 w/v% for the concentration of NaCl. Validation of HF-LPME was performed with limit of detection (LOD), limit of quantitation (LOQ), dynamic range, reproducibility, and recovery. The results obtained from this study indicated that HF-LPME was suitable for the preconcentration method and the quantitative analysis to characterize FAMEs in bio-liquid generated from food waste via HTC reaction.

• Korean Journal of Materials Research
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• v.28 no.3
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• pp.182-188
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• 2018

Nitrogen (N)-doped protein-based carbon as platinum (Pt) catalyst supports from tofu for oxygen reduction reactions are synthesized using a carbonization and reduction method. We successfully prepare 5 wt% Pt@N-doped protein-based carbon, 10 wt% Pt@N-doped protein-based carbon, and 20 wt% Pt@N-doped protein-based carbon. The morphology and structure of the samples are characterized by field emission scanning electron microscopy and transmission electron micro scopy, and crystllinities and chemical bonding are identified using X-ray diffraction and X-ray photoelectron spectroscopy. The oxygen reduction reaction are measured using a linear sweep voltammogram and cyclic voltammetry. Among the samples, 10 wt% Pt@N-doped protein-based carbon exhibits exellent electrochemical performance with a high onset potential of 0.62 V, a high $E_{1/2}$ of 0.55 V, and a low ${\Delta}E_{1/2}=0.32mV$. Specifically, as compared to the commercial Pt/C, the 10 wt% Pt@N-doped protein-based carbon had a similar oxygen reduction reaction perfomance and improved electrochemical stability.

• Journal of the Korean Wood Science and Technology
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• v.36 no.4
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• pp.44-51
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• 2008

In this study, the effects of carbonization temperature on the physico-chemical properties of Korean red-pine wood (Pinus densiflora S. et Z.) powder charcoal are studied by elemental analysis, nitrogen adsorption-desorption and SEM techniques. The surface structure and physico-chemical properties of the wood charcoal greatly depend on the carbonization temperature and their temperature dependences for sapwood (swd) and heartwood (hwd) are qualitatively analogous. Because of the differences in characteristics such as hardness and composition between heartwood and sapwood, charcoals from heartwood have larger specific surface area and smaller average pore diameter than that from sapwood. Because the decomposition reaction mostly proceeds in the precarbonization stage, the charcoal produced in this stage mainly consists of carbon. The second carbonization reaction is insignificant but still proceeds up to $700^{\circ}C$, and the specific surface area continuously increases. Above $800^{\circ}C$, the surface area is reduced by the pore-filling and narrowing effects and especially above $900^{\circ}C$, new carbon phase with hexagonal column rooted into the pore is formed. The nitrogen adsorption-desorption isotherm of the charcoal is classified as type I and its hysteresis loop was as type H4.

• Applied Chemistry for Engineering
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• v.23 no.5
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• pp.440-444
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• 2012

In this work, a semi-carbonized wood chip (SC-WC) was prepared by heat-treatment at low carbonization temperature. The pyrolysis characterization and heating value of the SC-WC at different heat-treatment temperature were evaluated. The pyrolysis characterization and heating value of the SC-WC were determined using thermal gravimetric analyzer (TGA) in $N_{2}$ atmosphere and calorimeter, respectively. From the TGA results, the thermal decomposition reaction of the SC-WC treated at by low temperature was similar to pure wood chip and the reaction was most actively occurred in the range of $200^{\circ}C$ to $400^{\circ}C$, whereas the initial thermal decomposition temperature of the SC-WC increased with the increasing heat-treatment temperature. In addition, the heating value of the SC-WC showed a similar trend as to the decamposition temperature behavior. This is probably attributed to increased carbon content of SC-WC by the localized carbonization of the wood chip which consisted of cellulose, hemi-cellulose, and lignin.

• The Korean Journal of Ceramics
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• v.4 no.3
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• pp.245-248
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• 1998

Porous carbon fiber composites (CFCs) having variable specific surface area ranging 35~1150 $\m^2$/g were reacted to produce silicon carbide fiber composites with SiO vapor generated from a mixture of Si and $SiO_2$ at 1673 K for 2 h under vacuum. Part of SiO vapor generated during conversion process condensed on to the converted fiber surface as amorphous silica. Chemical analysis of the converted CFCs resulting from reaction showed that the products contained 27~90% silicon carbide, 7~18% amorphous silica and 3~63% unreacted carbon, and the composition depended on the specific carbide, 7~18% amorphous silica and 3~63% unreacted carbon, and the composition depended on the specific surface area of CFCs. CFC of higher specific surface area yielded higher degree of conversion of carbon to silicon and conversion products of lower mechanical strength due to occurrence of cracks in the converted caron fiber. As the conversion of carbon to silicon carbide proceeded, pore size of converted CFCs increased as a result of growth of silicon carbide crystallites, which is also linked to the crack formation in the converted fiber.