研究者詳細 - 坪田　敏樹

論文 - 坪田　敏樹

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The investigation of activated carbon by K<inf>2</inf>CO<inf>3</inf> activation: Micropores- and macropores-dominated structure 査読有り国際誌

Khuong D.A., Kieu T.T., Nakaoka Y., Tsubota T., Tashima D., Nguyen H.N., Tanaka D.

Chemosphere 299 2022年07月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

In this study, the K2CO3 activation of bamboo was investigated in detail, and the structure and properties of the prepared activated carbons were tested for the feasibility of CO2 capture application and the potential for both ion and bacteria adsorption for use in the field of hazardous wastewater treatment. Activated carbons were produced with different activator ratios, from 0.5 to 6 according to the sample mass ratio. The ratio of H or O to C (H/C or O/C) increased with the increasing amount of K2CO3 added for the activation. The samples had a highly-porous microporous structure, in which the micropore volume was calculated to be 0.6 cm3 g−1 by the DR method of the CO2 adsorption isotherm at 298 K. The BET surface area and total pore volume estimated from the N2 adsorption isotherms at 77 K of the activated materials increased according to the increase of the K2CO3 impregnation ratio to a maximum value of 1802 m2 g−1 and 0.91 cm3 g−1, respectively. Moreover, the K2CO3-activated samples had a specific morphology, that is, macropores which are presumed to be derived from bubbles. The X-ray-CT images showed that the bubble-like structure is not only on the surface but also inside the samples. The results of gas adsorption methods, mercury porosimetry, and SEM showed the co-existence of micropores (<2 nm) and macropores (100–10,000 nm). The results highlighted the unique pore structure, that is, the coexistence of micropores and macropores that would contribute to forming solutions for carbon sequestration in the atmosphere and wastewater treatment.

DOI： 10.1016/j.chemosphere.2022.134365

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Activated carbon produced from bamboo and solid residue by CO2 activation utilized as CO2 adsorbents 査読有り国際誌

Duy AnhKhuong, Hong NamNguyen, ToshikiTsubota

Biomass and Bioenergy 148 106039 2021年05月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Bamboo and its solid residue after hydrothermal treatment were converted successfully into porous carbon by physical activation with the CO2 agent. The solid residue exhibits a higher potential to form activated carbon thanks to its very low ash content (almost 0%). The porosity and CO2 uptake of the carbon materials were characterized by the N2 and CO2 adsorption/desorption techniques. The results showed a dominant microporous structure in the carbon derived from both bamboo and solid residue. The highest BET surface area that the carbon material from bamboo could achieve was 976 m2 g−1, meanwhile, this value at the carbon prepared from solid residue activated at the same temperature was 1496 m2 g−1. The microporosity structure of activated carbon could be stimulated and enhanced at the optimal condition of CO2 activation. The CO2 adsorption capacity of the carbon made from bamboo and the solid residue was also analyzed with good capacity (3.4 mmol g−1) comparing to the 3 reference materials at the same condition of adsorption (293 K, 1 atm).

DOI： 10.1016/j.biombioe.2021.106039

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CO2activation of bamboo residue after hydrothermal treatment and performance as an EDLC electrode 査読有り国際誌

Duy Anh Khuong, Hong Nam Nguyen, Toshiki Tsubota

RSC Advances 11 ( 16 ) 9682 - 9692 2021年02月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

CO2activation of the solid residue of bamboo after hydrothermal treatment, which is used for the production of xylo-oligosaccharide, was investigated in detail. The reference temperature for carbonization and CO2activation was 800 °C. The activated carbon from a solid residue was demonstrated to have a higher potential for making EDLC electrodes than bamboo activated carbon thanks to its very low ash content (almost 0) and high porosity structure with a BET surface area up toca.2150 m2g−1. The electrochemical performance of ELDC electrodes prepared from solid residue-derived activated carbon in 1 M H2SO4aqueous solution was measured and well compared with carbon from bamboo. Through investigation, it is clear that the capacitance of the electrode made from the solid residue has a better capacity than that of raw bamboo.

DOI： 10.1039/d1ra00124h

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Utilization of pine tree biochar produced by flame-curtain pyrolysis in two non-agricultural applications 査読有り国際誌

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

Bioresource Technology Reports 9 2020年02月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 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： 10.1016/j.biteb.2020.100384

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Retraction Note: Low-cost novel nano-constructed granite composites for removal of hazardous Terasil dye from wastewater (Environmental Science and Pollution Research, (2022), 30, 34, (81333-81351), 10.1007/s11356-022-21367-8) 査読有り

Khalil M., Hanif M.A., Rashid U., Ahmad J., Alsalme A., Tsubota T.

Environmental Science and Pollution Research 31 ( 51 ) 2024年11月

掲載種別：記事・総説・解説・論説等（その他）

The Publisher has retracted this article in agreement with the Editor-in-Chief. An investigation by the publisher found a number of articles, including this one, with a number of concerns, including but not limited to compromised peer review process, inappropriate or irrelevant references, containing nonstandard phrases or not being in scope of the journal. Based on the investigation's findings the publisher, in consultation with the Editor-in-Chief therefore no longer has confidence in the results and conclusions of this article. The Publisher has not been able to obtain a current email address for Maria Khalil. The other authors have not responded to correspondence regarding this retraction.

DOI： 10.1007/s11356-024-35374-4

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Comprehensive Understanding of the Impact of Alkaline-Activated Bamboo-Derived Carbon for Enhancing Supercapacitor Performance 査読有り

Khuong D.A., Tsubota T., Nguyen H.N.

Journal of Physical Chemistry C 128 ( 41 ) 17313 - 17327 2024年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

This study explored the potential of steam-treated bamboo-derived activated carbon (AC) for electric double-layer capacitor (EDLC) applications, using KOH, K2CO3, and Na2CO3 as activation agents to improve electrode materials. The activation process significantly affected the textural properties: KOH enhanced the surface area and micropore volume, K2CO3 impacted micropores and macropores, and Na2CO3 contributed to mesopores and macropores. TEM and SEM images showed distinct morphologies, with K2CO3 exhibiting bubble-like structures and Na2CO3 displaying a foam-like appearance. X-ray photoelectron spectroscopy analysis revealed specific surface modifications of ACs. Electrochemical performance assessments, including charge-discharge behavior, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS), demonstrated the superiority of KOH-AC in EDLC applications due to its high specific area and microporosity. The discharge capacitance of EDLC made from KOH-AC reached 24 F g-1 at a current density of 100 mA g-1, while those from K2CO3 and Na2CO3-AC did not surpass 14 F g-1 under the same conditions. Fitting EIS data with the electrical circuit model partially revealed correlations between ion diffusion and capacitance values, although further durability studies are needed for practical applications. This investigation provides valuable insights into optimizing steam-treated bamboo-derived AC for advanced energy storage systems.

DOI： 10.1021/acs.jpcc.4c04228

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Valorization of bamboo and cedar bark residues for the production of biochars as adsorbents of CO<inf>2</inf> and radionuclides 査読有り国際誌

Trinh K.T., Khuong D.A., Viet D.D., Tsubota T., Ioannidis I., Pashalidis I., Kalderis D.

Sustainable Chemistry and Pharmacy 41 2024年10月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The escalating issues of rising CO2 emissions and radioactive pollution, specifically from isotopes like 232U and 241Am, present critical global environmental challenges. This study utilized bamboo and Japanese cedar as biomass sources for biochar production, aiming to investigate the influence of carbonization temperature on the biochars capacity to adsorb CO2 and radionuclides. The biochars were produced at 500, 600 and 700oC and underwent a comprehensive structural and material property analyses employing electron microscope, gas adsorption isotherms, and spectroscopy methods. Characterization revealed that the biochar samples predominantly consisted of micropores, whereas the Japanese cedar biochars exhibited elevated mesoporous surfaces compared to bamboo-derived biochars, along with the presence of oxygen-containing moieties on their surface. Remarkably, the results indicate a positive correlation between carbonization temperature and adsorption capacity for both CO2 and the radionuclides. Notably, biochars produced at 700 °C exhibited the highest CO2 adsorption capacity of 2.21 mmol g−1. While both bamboo and cedar biochars exhibited comparable adsorption behavior against CO2, Japanese cedar biochars demonstrated superior capacity for adsorbing 232U and 241Am compared to bamboo biochars. JC700 showed the optimum adsorption behavior, achieving 91 and 88% removal of 232U and 241Am at pH 4, respectively. These findings highlight the potential of both bamboo and Japanese cedar biochars as effective adsorbents for mitigating CO2 emissions and radioactive pollution.

DOI： 10.1016/j.scp.2024.101677

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Simultaneous syngas and CO<inf>2</inf> adsorbent production via rice straw gasification: An experimental study 査読有り国際誌

Nguyen H.N., Tran-Nguyen P.L., Khuong D.A., Tsubota T.

Biomass and Bioenergy 183 2024年04月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

Despite being a promising biomass source for gasification, the practical use of rice straw in Vietnam is hindered by its low gasification efficiency. This study introduces an innovative approach by integrating the production of syngas and CO2 adsorbent during the gasification process of rice straw, departing from the conventional focus solely on improving gasification efficiency. Results showed that the gasification of rice straw, conducted in the 20 kWe commercial gasification system (PP20 All Power Lab), attained a thermal conversion efficiency of 58.7%. Syngas produced exhibited consistent composition, with CO and H2 content ranging from 12.1% to 15%, CO ranging from 16.9% to 22.1%, and CH4 ranging from 1.9% to 3.9% throughout the operation, demonstrating relative stability. Notably, a considerable amount of residual char, accounting for 22.1 wt% of the initial feedstock, was generated. Characterized by notable traits such as high surface basicity, aromaticity, and a dense concentration of (ultra-)micropores, the residual char demonstrates suitability for applications in CO2 adsorption. In controlled laboratory conditions (25 °C, 1 atm, without heat-mass transfer limitations), the adsorption capacity reached 1.2 mmol g−1. Transitioning to more practical conditions (40 °C, 1 atm, within a 2-cm adsorbent bed subject to diffusion constraints), the CO2 adsorption capacity of the residual char ranged between 2% and 4.8% of the adsorbent's weight, while the CO2/N2 selectivity measured between 25.5 and 29.7. These findings underscore the significant potential of integrating syngas and CO2 adsorbent production through rice straw gasification, indicating a promising avenue for sustainable energy and carbon capture technologies.

DOI： 10.1016/j.biombioe.2024.107137

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Autohydrolysis treatment of bamboo and potassium oxalate (K<inf>2</inf>C<inf>2</inf>O<inf>4</inf>) activation of bamboo product for CO<inf>2</inf> capture utilization 査読有り国際誌

Viet D.D., Thao D.T., Anh K.D., Tsubota T.

Frontiers of Chemical Science and Engineering 18 ( 4 ) 2024年04月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Typically, the hydroxide agents, such as sodium hydroxide and potassium hydroxide, which have corrosive properties, are used in the carbon activation process. In this study, potassium oxalate (K2C2O4), a less toxic and non-corrosive activating reagent, was used to synthesize activated carbon from the solid residue after autohydrolysis treatment. The effect of the autohydrolysis treatment and the ratio of the K2C2O4/solid residue are presented in this study. Moreover, the comparison between the activated carbon from bamboo and biochar from the solid residue are also reported. The resulting activated carbon from the solid residue exhibited a high surface area of up to 1432 m2·g−1 and a total pore volume of up to 0.88 cm3·g−1. The autohydrolysis treatment enhanced the microporosity properties compared to those without pretreatment of the activated carbon. The microporosity of the activated carbon from the solid residue was dominated by the pore width at 0.7 nm, which is excellent for CO2 storage. At 25 °C and 1.013 × 105 Pa, the CO2 captured reached up to 4.1 mmol·g−1. On the other hand, the ratio between K2C2O4 and the solid residue has not played a critical role in determining the porosity properties. The ratio of the K2C2O4/solid residue of 2 could help the carbon material reach a highly microporous textural property that produces a high carbon capture capacity. Our finding proved the benefit of using the solid residue from the autohydrolysis treatment as a precursor material and offering a more friendly and sustainable activation carbon process. (Figure presented.)

DOI： 10.1007/s11705-024-2402-8

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Valorization of Aloe vera waste for the production of Ca and P-rich hydrochars 査読有り国際誌

Kalderis D., Stavroulakis G., Tsubota T., Çalhan S.D.

Sustainable Chemistry for the Environment 5 2024年03月

記述言語：英語掲載種別：研究論文（学術雑誌）

The production of gel from Aloe vera plants is an emerging industry, however the residual leaves are considered waste and are not utilized. The purpose of this work was to prepare hydrochars from Aloe vera leaves under different conditions, and determine the fate of macro- and micronutrients in the solid products, in view of developing a novel biofertilizer. In this framework, distilled water, citric acid and potassium hydroxide solutions were used as feedwaters and the experiments were performed at the temperatures of 180 and 220 °C and treatment times of 1 – 8 h. All obtained hydrochars had increased Ca and P contents compared to the feedstock, whereas the highest Ca and P concentration of 10.4% and 7382 mg kg−1, respectively, were achieved under alkaline conditions after 8 h of treatment. Citric acid promoted carbonization, achieving H/C = 1.11, O/C = 0.34 of the hydrochar obtained at 220 °C after 8 h of treatment. The use of KOH counterbalanced the production of acids from the degradation of the biomass, thus restricting the carbonization progress. The metals K, Fe, Cu and Mg showed high solubilization tendencies, however their concentrations on the hydrochars increased beyond the 4 h treatments due to precipitation and re-sorption phenomena. The N content in the hydrochars ranged between 0.56 – 1.12%, increasing with temperature and time due to the formation and precipitation of pyridine, pyrroline and pyrrolidine derivatives. Overall, due to the high ash content, low pH and increased Ca and P concentrations, the hydrochars may be suitable as substrates for the development of bio-fertilizers purposed for alkaline soils.

DOI： 10.1016/j.scenv.2023.100057

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Experimental investigation of CO<inf>2</inf> adsorption using adsorbents derived from residual char of agricultural waste gasification 査読有り国際誌

Nguyen H.N., Khuong D.A., Tsubota T.

Thermal Science and Engineering Progress 49 2024年03月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）

This study proposed a novel approach, suggesting a cascading utilization of agricultural residues for both energy generation and the production of CO2 adsorbents through gasification. Gasification was carried out employing a 20 kWe commercial gasification system with macadamia nut shell, bagasse, and rice straw. Subsequently, post-gasification residues were meticulously collected, analyzed and utilized for CO2 adsorption experiments. Among these residual chars, macadamia nut shell demonstrated the highest CO2 adsorption capacity, followed by bagasse, while rice straw showed moderate performance. In laboratory conditions (25 °C, 1 bar, without the influence of ambient moisture or CO2 diffusion constraint), the post-gasification residue from macadamia nut shell achieved a CO2 adsorption capacity of 2.8 mmol g−1, followed by bagasse (2.4 mmol g−1). Transitioning to more practical conditions (25 °C, 1 bar, considering the influence of ambient moisture and CO2 diffusion limitations within an adsorbent bed), the macadamia nut shell and bagasse residual chars reached 2.7 mmol g−1 and 2.3 mmol g−1, respectively. Moreover, these chars exhibited noteworthy CO2/N2 selectivity and recyclability, making them comparable to various advanced CO2 adsorbents investigated in prior studies. The superior performance of the macadamia nut shell-derived residual char can be attributed to its highest microporous/ultra-microporous volumes and concentrations of basic and aromatic functional groups on the char's surface. The results of this study open up the potential for different strategies in combining the production of energy and affordable and upscalable CO2 adsorbents for industrial applications.

DOI： 10.1016/j.tsep.2024.102446

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Synergistic effect of the heterojunction g-C<inf>3</inf>N<inf>4</inf>/Bi<inf>2</inf>MoO<inf>6</inf>/clinoptilolite to enhance the photocatalytic degradation of antibiotics in water in the presence of persulfate 査読有り

Le P.T., Nguyen T.P., Do T.H., Nguyen H.N., Dinh T.M.T., Phan T.T., Tsubota T., Nguyen T.D.

Environmental Science: Water Research and Technology 2024年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

A novel and highly efficient photocatalyst, g-C3N4/Bi2MoO6/clinoptilolite nanocomposite (CNBC), was synthesized by a hydrothermal method and acted as a Z-scheme heterojunction for efficient activation of peroxydisulfate (PDS) to degrade oxytetracycline (OTC) under visible light (vis) irradiation. The morphology and structure of the photocatalyst were determined by XRD, FT-IR, FE-SEM, EDX, BET, TGA, UV-vis DRS, PL, and XPS. The results showed that CNBC-30 had the best photocatalytic performance with an OTC removal efficiency of more than 87% within 120 min under the conditions of [OTC] = 20 mg L−1, [catalyst] = 500 mg L−1, [Na2S2O8] = 1.26 mM, and pH = 4 at room temperature, which was much better than those of pure g-C3N4, Bi2MoO6, and CNB composites. This superiority is due to the excellent adsorption ability of clinoptilolite that effectively forms the g-C3N4/Bi2MoO6 heterojunctions, thus improving the ability to separate charge carriers while decreasing the recombination rate of electron-hole pairs. Furthermore, the effect of catalyst dosage, oxidant concentration, initial pollutant concentration, solution pH, and coexisting anions on the OTC degradation was comprehensively studied. The results showed that the CNBC-30/PDS system had high reusability and adaptability at different pH levels (3.0-11.0). Quenching tests showed that 1O2, O2˙−, and h+ played the main roles in OTC degradation. In addition, OTC intermediates were identified and degradation pathways were proposed based on the results of MS analysis. DFT calculations successfully predicted the positions on the OTC molecule with high Fukui numbers that are suitable for attack by oxidants. CNBC-30 was stable for OTC degradation after four cycles with a degradation efficiency of above 78%, demonstrating its durability and potential for practical applications. This study provides insight into PDS activation in the visible light region by a clinoptilolite-based Z-scheme heterojunction for organic pollutant degradation.

DOI： 10.1039/d4ew00549j

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Europium removal from aqueous solutions by oxidized biochar prepared from waste palm tree fronds 査読有り国際誌

Georgiou E., Ioannidis I., Pashalidis I., Viet D.D., Tsubota T., Kalderis D.

Sustainable Chemistry for the Environment 4 2023年12月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

Palm oil is a product of major economic importance worldwide however, palm tree cultivation generates large quantities of palm fronds as waste. In this work, the sorption of Eu3+ from aqueous solutions by oxidized biochar derived from palm tree fronds was studied at pH 3 by batch type experiments under ambient conditions. Following biochar production, the sample was oxidized using HNO3 to increase the oxygen-containing moieties on its surface. The oxidized biochar was characterized through surface and spectroscopic techniques. As indicated by the coefficient of determination value of 0.99, Eu3+ adsorption was best described by the Langmuir isotherm model. The optimum adsorption capacity was determined at qmax= 0.81 mol kg−1. Adsorption was an entropy-driven process and followed the 2nd order kinetics, reaching a plateau value of 50% relative adsorption within 60 min. Furthermore, Fourier Transform InfraRed spectroscopic data and the effect of ionic strength indicated that adsorption proceeded via the development of inner-sphere complexes between Eu3+ and the carboxylic groups on the biochar surface.

DOI： 10.1016/j.scenv.2023.100040

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Effect of solvent and acid catalyst selection on lignin recovery and purity in autoclave-assisted organosolv extraction 査読有り国際誌

Farid M.A.A., Ibrahim I., Lease J., Tsubota T., Andou Y.

Bioresource Technology Reports 24 2023年12月

記述言語：英語掲載種別：研究論文（学術雑誌）

This study leverages the autoclave-assisted method to explore a range of acid catalysts (H2SO4, HCl, HNO3, H3PO4) and solvents (methanol, ethanol, acetone, 2-butanol, 2-propanol) for lignin extraction, with a focus on identifying optimal efficiency-enhancing combinations. By contrasting the performance of various acid catalysts and solvents, this work transcends previous efforts in this field. Notably, H2SO4 yields the highest lignin recovery (44.7 %) but with lower purity (78.4 %) compared to HCl (85.7 %) in the same solvent. Methanol yields the highest recovery (45.1 %), yet lower purity (79.2 %) than ethanol (85.7 %) with a similar catalyst. A pivotal improvement lies in the elucidation of structural purity, substantiated by IR and NMR resulting signals, supported by microscale morphology and chemical composition (SEM-EDX). This study extends current understanding, providing profound insights into optimizing extraction procedures for producing lignin with desired attributes.

DOI： 10.1016/j.biteb.2023.101622

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Use of the Wise method as a pretreatment for the selective removal of lignin when preparing bamboo-activated carbon 査読有り国際誌

Tsubota T., Khuong D.A., Nagaoka H., Kumagai S., Andou Y.

Advances in Bamboo Science 5 2023年11月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

The Wise method, which is known in wood science as a technique for the quantitative analysis of holocellulose, was applied as a pre-treatment to prepare a porous precursor for activated carbon. The precursor has a specific pore size structure derived from the organizational architecture of the natural plant. The lignin in the plant tissue of the bamboo was successfully removed in a stepwise fashion by the Wise method treatment. All the N2 adsorption isotherms at 77 K for the carbonized samples, including the samples treated by the Wise method, were similar in shape. Specifically, they were type I as classified by IUPAC with low-pressure hysteresis, and there was no specific effect of the selective removal of lignin from the carbonized sample. However, after CO2 activation for more than 2 h, samples treated with the Wise method had slit pores, which is type H4 as classified by IUPAC. The slit width calculated by the INNES method, which is the theory for slit-type mesopores, was ca. 2.5 nm. When samples delignified by more than 60% were activated by CO2 for 3 h, the percentage of the micropores in the total pores was ca. 40%. Samples treated by the Wise method for the stepwise selective removal of lignin, should enable pore structure derived from plant tissue to be controlled in the activated carbon.

DOI： 10.1016/j.bamboo.2023.100049

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Supercapacitors composed of Japanese cedar bark-based activated carbons with various activators 査読有り国際誌

Trinh K.T., Tsubota T.

Materials Chemistry and Physics 307 2023年10月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

This study provided an overview of how pore structures and functional groups influence the electrochemical behaviors of activated carbons derived from a new type of biomass waste - Japanese cedar bark (JCB) with four different activators, i.e., KOH, K2CO3, H3PO4, and ZnCl2. Based on the chemical composition, microstructure, gas adsorption isotherms, and electrochemical analytical techniques, relationships between the pore structures, functional groups, and electrochemical behavior of the activated samples were assessed. The K2CO3 and KOH activated materials, designated KC-6 and KO-6, respectively, with an activation ratio of 6 (6 g an activator/1 g of JCB), were well rated for their electrochemical capabilities. At 10 mA g−1, these two samples had a specific capacitance of roughly 210 F g−1. The high electrochemical potential of KC-6 was attributed to a particular hierarchical structure comprised of micro-meso-macropores and rich oxygen functional groups on its surface, allowing faster ion diffusion and more effective ion adsorptions. Furthermore, in the case of the 1 M H2SO4 electrolyte, KO-6 had the largest specific surface area of 3000 cm2 g−1 and appropriate micropores (diameters (d) < 1.2 nm) for the electrolyte ion adsorptions, thus allowing this model to maintain an 80% specific capacitance for approximately 6500 Cyclic Voltammetry cycles at 1 mV s−1. The pore properties, functional groups, and electrochemical properties of the activated material derived from JCB can be controlled to some extent by the activator selections and experimental conditions.

DOI： 10.1016/j.matchemphys.2023.128148

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The production of high-value products derived from bamboo by steam pretreatment: Sugar-contained water solution and solid residue as a precursor for EDLC electrode 査読有り国際誌

Khuong D.A., Saza S., Tsubota T.

Materials Chemistry and Physics 304 2023年08月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

In this study, the effect of steam treatment on bamboo in several conditions was comprehensively investigated. The sugar-contained water derived from bamboo could be extracted by the proper condition of steaming time and temperature. The highest amount of sugar content was 1.9oBx, found at the steaming condition of 200 °C and 2.5 h. The raw bamboo and the solid residue after steam treatment were converted into porous carbon by KOH activation. By the N2 adsorption/desorption isotherm analysis, the textural structures of activated carbons in the research were determined as the dominated-microporous structure. The BET specific area of activated carbon derived from the solid residue was up to 3445 m2 g−1. The microporous structure stimulated by KOH activation helped enhance the electrical performance of the carbon electrode for EDLC. Based on the electrochemical measurements, the capacitances of the samples derived from the solid residue were higher than that derived from bamboo. The results suggested that the steaming process was an effective pretreatment to take full advantage of the properties of bamboo.

DOI： 10.1016/j.matchemphys.2023.127853

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Catalytic graphitization of biomass-derived ethanosolv lignin using Fe, Co, Ni, and Zn: Microstructural and chemical characterization 査読有り国際誌

Farid M.A.A., Zheng A.L.T., Tsubota T., Andou Y.

Journal of Analytical and Applied Pyrolysis 173 2023年08月

記述言語：英語掲載種別：研究論文（学術雑誌）

Bamboo has just recently emerged as a sustainable source of lignin extraction, paving the way for the development of sophisticated nano- and biomaterials based on lignin. Catalytic pyrolysis effectively synthesized graphitic carbon from biomass resources. This article investigates the influence of various metals (Fe, Co, Ni, and Zn) as catalysts in the catalytic graphitization of bamboo biomass-derived lignin. The graphitization process was carried out through thermal treatments conducted in a tightly closed muffle furnace at 1100 ℃ for a duration of 4 hrs. The metals-catalyzed graphitic carbons appeared flake-like microstructures under SEM with > 80 wt% graphitized carbon composition detected by XPS. Enhancement in the degree of graphitization, crystallite size, interlayer distance, and structural order was achieved within the order of Fe>Co>Ni>Zn. These are corroborated by XRD, indicating Fe-catalyst resulted in lignin graphite with a degree of graphitization of 92.07%, crystallite size (Lc) of 230.2 nm, and interlayer distances of 0.336 nm that are closer to commercial graphite. Raman revealed the Fe-catalysed lignin graphite has a lower defective ratio (ID/IG) of 0.55, while all graphitized lignin showed IG/I2D of > 1.0, indicating multiple layers of graphitic carbon. These findings might pave the way for future high-value graphite-based materials made from low-cost biomass, making it an intriguing prospect.

DOI： 10.1016/j.jaap.2023.106064

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Recycling marine plastic waste to energy storage devices 査読有り国際誌

Tashima D., Kashio T., Eguchi T., Kumagai S., Tsubota T., Madden J.D.W.

Materials Letters: X 18 2023年06月

記述言語：英語掲載種別：研究論文（学術雑誌）

In this study, a method was developed for the management of marine plastic waste via the production of activated carbon. The specific surface area, micropore volume, and mesopore volume of marine-plastic-based activated carbon prepared at selected temperatures and using selected activator weight ratios were measured, and the specific capacitance and supercapacitor electrode performance were evaluated. At an activation temperature of 800 °C and a raw material to 8 M KOH weight ratio of 1:7, a specific capacitance of 201F/g and a high surface area of 2389 m2/g were obtained. Therefore, marine plastic waste-based activated carbon can be used as the electrode material in supercapacitors.

DOI： 10.1016/j.mlblux.2023.100193

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Bamboo-derived adsorbents for environmental remediation: A review of recent progress 査読有り国際誌

Kalderis D., Seifi A., Kieu Trang T., Tsubota T., Anastopoulos I., Manariotis I., Pashalidis I., Khataee A.

Environmental Research 224 2023年05月

記述言語：英語掲載種別：研究論文（学術雑誌）

The bamboo family of plants is one of the fastest-growing species in the world. As such, there is an abundance of bamboo residues available for exploitation, especially in southeast Asian, central African and south American regions. The preparation of efficient adsorbents from bamboo residues is an emerging exploitation pathway. Biochars, activated carbons or raw bamboo fibers embedded with nanoparticles, each class of materials has been shown to be highly efficient in adsorption processes. This review aims to summarize recent findings in the application of bamboo-based adsorbents in the removal of organic, inorganic, or gaseous pollutants. Therefore, this review first discusses the preparation methods and surface modification methodologies and their effects on the adsorbent elemental content and other basic properties. The following sections assess the recent progress in the adsorption of heavy metals, organics, and gaseous substances by bamboo-based adsorbents, focusing on the optimum adsorption capacities, adsorption mechanisms and the optimum-fitting kinetic models and isotherms. Finally, research gaps were identified and directions for future research are proposed.

DOI： 10.1016/j.envres.2023.115533

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85149418388&origin=inward

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