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• Humidity adsorption characteristics of Moso bamboo charcoal oxidized at room temperature by HNO<inf>3</inf>

  Viet D.D., Tsubota T., Shinogi Y.

  Journal of the Indian Academy of Wood Science    17 ( 1 ) 34 - 41   2020年06月  [査読有り]

   概要を見る

  © 2020, Indian Academy of Wood Science. The bamboo charcoals (BC) in various range pyrolysis (400–900 °C) were modified by HNO3, and then the samples were tested for water vapor adsorption. The adsorption experiments were conducted follows to Japanese industrial standard JIS A 1470-1-2002. The physical and chemical properties of the samples were studied by scanning electron microscope, Brunauer–Emmett–Teller surface area analysis, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.The humidity adsorption tests show that the modified BC samples with HNO3 at room temperature (about 22 °C) in pyrolysis temperature (400–500 °C) have a significant enhancement than the control one at lower relative humidity (< 60%). This characteristic is an advantageous application in conservation needs extremely low humidity. Specific surface area and total pore volume are supposed to play an important role for humidity adsorption at high relative humidity (> 60%). Whereas, at low relative humidity, surface functional groups on BC are a dominant factor compared to specific surface area on humidity adsorption.

  DOI Scopus

• Release kinetics of potassium from silica-rich fern-derived biochars

  Nguyen A.T.Q., Bui T.A., Mai N.T., Tran H.T., Tran S.V., Nguyen N.H., Tsubota T., Shinogi Y., Dultz S., Nguyen M.N.

  Agronomy Journal    112 ( 3 ) 1713 - 1725   2020年05月  [査読有り]

   概要を見る

  © 2020 The Authors. Agronomy Journal © 2020 American Society of Agronomy Recently, low input agriculture has been encouraged because of its sustainability and environmentally friendly vision. Conversion of biomass into control-released materials is one of the approaches to upcycle biomass and nutrients. This study aims at examining the dynamics of K release from Si-rich biochars formed from various pyrolysis strategies with the findings expected to be applicable to develop new refinery strategies for biomass nutrients. A Si-rich fern species [Dicranopteris linearis (Burm.f.) Underw.] was selected to prepare biochars under various pyrolysis conditions (e.g., temperature, N2 supported). It was found that K was re-located during pyrolysis and occurred as free K+ ions, associated with organic matter and occluded in silica structure. Pyrolysis can be strategically applied to alter either the organic phase or the silica phase in the biochars in term of porosity and chemical reactivities, whereby controlling K release kinetics. The maximum level of released K was at 600 °C (5.4 g kg−1) which was about one order of magnitude higher than the minimum level of released K at 200 °C (0.55 g kg−1). This discrepancy in the release rates of K suggests that adjusting pyrolysis temperature can be a strategical practice to control K release and to develop biochar-based K fertilizers.

  DOI Scopus

• Utilization of pine tree biochar produced by flame-curtain pyrolysis in two non-agricultural applications

  Kalderis D., Tsuchiya S., Phillipou K., Paschalidou P., Pashalidis I., Tashima D., Tsubota T.

  Bioresource Technology Reports    9   2020年02月  [査読有り]

   概要を見る

  © 2020 Elsevier Ltd Main objective of this work was to demonstrate the applicability of biochars obtained from pine tree residues through low cost, easy to operate, flame-curtain pyrolysis, in two distinctively different applications. In the first application, it was shown that base-oxidized pine tree biochar had an excellent adsorption behavior towards U(VI) in aqueous solutions, achieving a qmax value of 800 mg g−1. It was also demonstrated that surface interactions with biochar's oxygen-containing groups dominated over physical interactions with the pore structure. In the second application, KOH-activated pine tree biochar showed a very promising behavior as an electrode material in an electron double-layer capacitor. Due to its high surface area (2500 m2/ g), capacitance values of 190 F g−1 at 10 mA g−1 for discharge process were achieved. As a conclusion, it was shown that flame-curtain pyrolysis biochars are suitable for non-agricultural applications, in the cases where soil application is not an option.

  DOI Scopus

• KOH activation of solid residue of Japanese citron after extraction by microwave process and property as EDLC electrode

  Tsubota T., Hohshi Y., Ohno T., Kumagai S.

  Journal of Porous Materials      2020年01月  [査読有り]

   概要を見る

  © 2020, Springer Science+Business Media, LLC, part of Springer Nature. The solid residue of Japanese citron after its compression to obtain juice and then the extraction of oil was used as the raw material of activated carbon in order to substantiate the cascading use of Citrease for several high value products. Most of the inorganic compounds in the carbonized samples were K4H2(CO3)3·1.5 H2O and CaCO3. Although the amount of these inorganic compounds was independent of the carbonization temperature, most of these inorganic compounds were removed by the KOH activation process. The BET specific surface area of the sample after the KOH activation increased with the increasing amount of KOH added for activation, and the value was greater than 1900 m2 g−1 when the amount of KOH was greater than 67 wt%. The pore sizes and pore volumes were calculated by several methods, such as the Langmuir, t method, αs method, MP method, BJH method, and INNES method, in order to analyze in detail the surface condition related to the pores. The capacitance value of the sample activated at KOH 75 wt% was 157 F g−1 at 1 mV s−1.

  DOI Scopus

• Fern Dicranopteris linearis-derived biochars: Adjusting surface properties by direct processing of the silica phase

  Mai N.T., Nguyen N.H., Tsubota T., Shinogi Y., Dultz S., Nguyen M.N.

  Colloids and Surfaces A: Physicochemical and Engineering Aspects    583   2019年12月  [査読有り]

   概要を見る

  © 2019 Elsevier B.V. This work specifically emphasizes the effect of the silica phase contained in the fern Dicranopteris linearis (D. linearis), a common shrub occurring widely throughout tropical and subtropical regions, on biochar surface properties. Slow pyrolysis was performed in the temperature range from 400 to 900 °C under various ambient reaction conditions, i.e., non-biochar-oriented conditions (open pyrolysis) and biochar-oriented conditions (closed and N2-supported pyrolysis). The resulting changes in micromorphology and different surface properties, specific surface area and surface charge, were elucidated. Open pyrolysis resulted in excessive decomposition of biomass and condensation of silica, while the closed and N2-supported pyrolysis methods showed notable enhancement of biochar yield. The presence of silica as an inter-embedded part of the fern D. linearis and the derived biochars likely supported a carbon-silica structural model in which these two components might be integrated or decomposed during pyrolysis. In general, joint processing of organic carbon and silica greatly altered the surface properties. At lower temperatures and during N2-supported pyrolysis, condensation of organic compounds limited the development of high surface charge densities. At higher temperatures and during open pyrolysis, intensification of the silica phase was accompanied with an increasing number of charged surface sites, thereby increasing the surface charge density. Based on the porous structure, large surface area (up to 701 m2 g−1) and high surface charge density (up to 0.5 μmol(−) m−2), D. linearis-derived biochars can be highlighted as potential agro-environmental materials.

  DOI Scopus

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• P-57 水熱処理によるイナワラからのフルフラール製造

  井上 誠一, 熊谷 聡, 坪田 敏樹

  バイオマス科学会議発表論文集  2018年01月  -  2018年01月   

   概要を見る

  <p>Rice straw was treated under hydrothermal condition for producing furfural, which is one of the degradation products of hemicellulose. The highest furfural yield (19.6 mg/g-rice straw) was obtained at 220°C for 15min under hydrothermal condition. Main product was furfural, but the other oxygenated compounds, such as acetic acid and formic acid, were also obtained at this condition. When the phosphoric acid solution was added to the compressed water, the yield of furfural increased remarkably, and the highest yield (26.0 mg/g-rice straw) of the furfural was obtained at 220 °C for 15min. It is shown that addition of phosphoric acid solution to the compressed water provided the higher yield to obtain the furfural from rice straw.</p>

  CiNii

• P-67 竹のカスケード利用によるキシロオリゴ糖の製造と電気二重層キャパシタ電極用炭素材料の開発

  坪田 敏樹, 石本 航太郎, 熊谷 聡, 林 信行

  バイオマス科学会議発表論文集  2017年01月  -  2017年01月   

   概要を見る

  <p>In order to use bamboo as the starting material for some high-value products, the production of carbon material, which is activated carbon, for the electrode of electric double layer capacitor (EDLC) was attempted from the bamboo residue after the compressed hot water treatment, which can produce xylo-oligosaccharide from bamboo. The bamboo powder after the treatment of 200 degrees C for 1 hour was used as the starting material of carbon material. The yield from the residue to activated carbon was ca. 10 % regardless of the carbonization temperature. The estimated specific surface areas by BET method for the prepared samples were ca. 2500 m2/g, except for the sample carbonized at 800 degrees C. The capacitance values of the samples were small at high current density. The reason for the small values should be large IR drop.</p>

  CiNii

• 電気二重層キャパシタの炭素電極における加熱処理の影響

  本人

  第36回炭素材料学会年会  (日本 仙台)  2009年12月  -  2009年12月   

• N-クロロコハク酸イミドを利用した水素化ダイヤモンド表面とピリジンカルボン酸および類似した化合物の反応性

  本人

  第23回ダイヤモンドシンポジウム   (日本 津田沼)  2009年11月  -  2009年11月   

• 半導体検査装置の電気接触子への導電性CVDダイヤモンド膜の応用

  本人

  第23回ダイヤモンドシンポジウム   (日本 津田沼)  2009年11月  -  2009年11月   

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