• Title, Summary, Keyword: Char

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Adsorptive removal of atmospheric pollutants over Pyropia tenera chars

  • Lee, Heejin;Park, Rae-su;Lee, Hyung Won;Hong, Yeojin;Lee, Yejin;Park, Sung Hoon;Jung, Sang-Chul;Yoo, Kyung-Seun;Jeon, Jong-Ki;Park, Young-Kwon
    • Carbon letters
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    • v.19
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    • pp.79-88
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    • 2016
  • As a replacement for activated carbon, biochar was synthesized and used for the adsorptive removal of formaldehyde and nitrogen oxide. Biochar was produced from the fast pyrolysis of the red marine macro alga, Pyropia tenera. The P. tenera char was then activated with steam, ammonia and KOH to alter its characteristics. The adsorption of formaldehyde, which is one of the main indoor air pollutants, onto the seaweed char was performed using 1-ppm formaldehyde and the char was activated using a range of methods. The char activated with both the KOH and ammonia treatments showed the highest adsorptive removal efficiency, followed by KOH-treated char, ammonia-treated char, steam-treated char, and non-activated char. The removal of 1000-ppm NO over untreated char, KOH-treated char, and activated carbon was also tested. While the untreated char exhibited little activity, the KOH-treated char removed 80% of the NO at 50℃, which was an even higher NO removal efficiency than that achieved by activated carbon.

Cu2+ ion reduction in wastewater over RDF-derived char

  • Lee, Hyung Won;Park, Rae-su;Park, Sung Hoon;Jung, Sang-Chul;Jeon, Jong-Ki;Kim, Sang Chai;Chung, Jin Do;Choi, Won Geun;Park, Young-Kwon
    • Carbon letters
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    • v.18
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    • pp.49-55
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    • 2016
  • Refuse-derived fuel (RDF) produced using municipal solid waste was pyrolyzed to produce RDF char. For the first time, the RDF char was used to remove aqueous copper, a representative heavy metal water pollutant. Activation of the RDF char using steam and KOH treatments was performed to change the specific surface area, pore volume, and the metal cation quantity of the char. N2 sorption, Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES), and Fourier transform infrared spectroscopy were used to characterize the char. The optimum pH for copper removal was shown to be 5.5, and the steam-treated char displayed the best copper removal capability. Ion exchange between copper ions and alkali/alkaline metal cations was the most important mechanism of copper removal by RDF char, followed by adsorption on functional groups existing on the char surface. The copper adsorption behavior was represented well by a pseudo-second-order kinetics model and the Langmuir isotherm. The maximum copper removal capacity was determined to be 38.17 mg/g, which is larger than those of other low-cost char adsorbents reported previously.

Adsorptive removal of odour substances and NO and catalytic esterification using empty fruit bunch derived biochar

  • Lee, Hyung Won;Kim, Jae-Kon;Park, Young-Kwon
    • Carbon letters
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    • v.28
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    • pp.81-86
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    • 2018
  • Empty fruit bunch (EFB) char was used to remove $NO_x$ and odorous substances. The physicochemical properties of the EFB chars were altered by steam or KOH treatments. The Brunauer-Emmett-Teller surface area and porosity were measured to determine the properties of the modified EFB chars. The $deNO_x$ and adsorption test for hydrogen sulphide and acetaldehyde were performed to determine the feasibility of the modified EFB chars. The KOH-treated EFB (KEFB) char revealed higher $deNO_x$ efficiency than with commercial activated carbon. The Cu-impregnated EFB char also had high $deNO_x$ efficiency at temperatures higher than $150^{\circ}C$. The KEFB char showed the highest hydrogen sulphide and acetaldehyde adsorption ability, followed by the steam-treated EFB char and untreated EFB char. Moreover, the product prepared by sulfonation of EFB char showed excellent performance for esterification of palm fatty acid distillate for biodiesel production.

Effect of Reaction Conditions of Pyrolysis on the Characteristics of Sludge Char (열분해 조건에 따른 슬러지 Char 특성 변화)

  • Cha, Jin-Sun;Park, Young-Kwon
    • Korean Chemical Engineering Research
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    • v.49 no.6
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    • pp.851-856
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    • 2011
  • In this study, char was produced via pyrolysis of sewage sludge and the effects of reaction conditions(temperature, heating rate, reaction time) on characteristics of char were investigated. As temperature increased from $300^{\circ}C$ to $800^{\circ}C$, the surface area of sludge char increased in general but decreased at $700^{\circ}C$ temporarily. The effect of heating rate on specific surface area and pore volume of char was not large. Meanwhile, specific surface area and pore volume increased with reaction time but average pore diameter decreased.

The Sentence Similarity Measure Using Deep-Learning and Char2Vec (딥러닝과 Char2Vec을 이용한 문장 유사도 판별)

  • Lim, Geun-Young;Cho, Young-Bok
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.22 no.10
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    • pp.1300-1306
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    • 2018
  • The purpose of this study is to see possibility of Char2Vec as alternative of Word2Vec that most famous word embedding model in Sentence Similarity Measure Problem by Deep-Learning. In experiment, we used the Siamese Ma-LSTM recurrent neural network architecture for measure similarity two random sentences. Siamese Ma-LSTM model was implemented with tensorflow. We train each model with 200 epoch on gpu environment and it took about 20 hours. Then we compared Word2Vec based model training result with Char2Vec based model training result. as a result, model of based with Char2Vec that initialized random weight record 75.1% validation dataset accuracy and model of based with Word2Vec that pretrained with 3 million words and phrase record 71.6% validation dataset accuracy. so Char2Vec is suitable alternate of Word2Vec to optimize high system memory requirements problem.

A Study on Heavy Metal Removal Characteristics Using Bone Char (골탄(bone char)의 중금속 제거 특성에 관한 연구)

  • Kim, Jae-Young;Kim, Hwan-Gi
    • Journal of Korean Society of Water and Wastewater
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    • v.21 no.2
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    • pp.253-258
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    • 2007
  • The adsorption capacity of bone char for lead, cadmium and zinc was studied in both single and binary multiple component systems. Equilibrium experimental studies have been performed to determine the sorption capacity of bone char for each metal ion. These have been analysed using single and multi-component equilibrum models. The results show that the sorption of metal ions for multi-component systems can be predicted reasonably well from the IAS theory with the Langmuir equation, the Freundlich and the Slip equation for metal ions.

High Char-Yield in AN-AM Copolymer by Acidic Hydrolysis of Homopolyacrylonitrile

  • Cheng, Run;Zhou, You;Wang, Jing;Cheng, Yumin;Ryu, Seungkon;Jin, Riguang
    • Carbon letters
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    • v.14 no.1
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    • pp.34-39
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    • 2013
  • Acrylonitrile (AN)-acrylamide (AM) copolymers were prepared by nitric acidic hydrolysis of homopolyacrylonitrile. The acrylamino group increased as a function of hydrolysis time, while crystallinity decreased. Differential scanning calorimetry and a thermal gravimetric analysis indicated that the acylamino introduced by acidic hydrolysis effectively enhanced the cyclization reaction at low temperature due to the change of the cyclization reaction mechanism. Char-yield of AN-AM copolymers also gradually increased with increasing hydrolysis time. The maximum char-yield was 49.48% when hydrolized at $23^{\circ}C$ in 65% nitric acid solution for 18 h, which was 30% higher than that of non-acidic hydrolysis of homopolyacrylonitrile. Simulation of the practical process also showed an increase of char yields, where the char yields were 55.43% and 62.60% for homopolyacrylonitrile and copolyacrylonitrile, respectively, with a hydrolysis time of 13 h.

The Characteristics of Sour Gas Decomposition by Microwave (Microwave에 의한 산성가스 분해 특성)

  • Kim, Dong-Sik;Kim, Jae-Surl;Lee, Dong-Kyu
    • Applied Chemistry for Engineering
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    • v.7 no.6
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    • pp.1027-1033
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    • 1996
  • Under the Irradiation of the radiofrequency wave, the dipole materials vibrate as microwavic phase change. This causes friction between adjacent molecules and enables an unique charateristics of interior heating of the materials. When dipole gases are adsorbed inside of a solid radiofrequency wave absorber, the gases can be decomposed easily by the microwave energy. The decomposition of sour gases was successfully tested in this manner to develop a sour gas removal process from the combustion flue gas. The standard gas bearing NO and $SO_2$ was passed through and microwave was applied on the calcined char bed as the wave absorber and the gas adsorbent. It was found that more then 95% of NO and 70 % of $SO_2$ was decomposed to the environmentally clean elements during the passage through the 20 gram char bed under the microwave impingement. The surface area and the porosity of char increased because the oxygen radicals produced from decomposed gas attacked carbon in the char capillaries and formed $CO_2$. For a lower concentration of sour gas, general cases in the commercial combustion processes, almost complete decomposion is believed possible and this method is surely expected to be useful for the prevention of air pollutions.

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The distribution of activation energy and frequency factor for coal pyrolysis and char-air reaction (열분해 및 촤 - 공기 반응시의 활성화 에너지 및 빈도계수 분포)

  • Park, Ho-Young;Kim, Young-Joo
    • Journal of Energy Engineering
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    • v.18 no.1
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    • pp.9-16
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    • 2009
  • The experimental work has been carried out for the study of pyrolysis and char-air reaction of five coals used in Y power station in Korea. For five coals, the characteristics of pyrolyis and char reaction have been investigated with TGA, and their kinetic parameters were obtained and compared each other. The order of pyrolysis rate for five coals were as follows : Peabody, Flame, MIP, Indominco, Elk valley. The behavior of char - air reaction for five coal chars have been successfully described by the grain model. The rate of char-air reaction gave the maximum value for Flame coal char, on the while Elk valley coal char had the minimum value. For the reaction temperature over 1,000K, Flame coal char - air reaction was very fast compared with other coal chars.

Sorption of copper ion on waste pig bone (돼지 폐(廢) 골분(骨粉)에 의한 구리이온 흡착(吸着))

  • Kim, Eun-Jung;Woo, Sung-Hoon;Park, Seung-Cho
    • Resources Recycling
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    • v.15 no.2
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    • pp.45-49
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    • 2006
  • The removal of copper ion from aqueous solution by adsorption with bone char that made from spent pig bone has been studied. This paper was studied the effects of bone char dosage and pH. The optimal results show that bone char adsorbs about 96.5 percent of copper ion in aqueous solution containing 50 mg/L as initial concentration at pH 5.0 when the bone char of 5g/L is used for 30 hours. Increase in the initial pH of the copper solution resulted in an increase in the copper ion uptake per weight of the sorbent Freundlich isotherm model was found to be applicable for the experimental data of $Cu^{2+}$.