研究等業績 - 原著論文 - 大川　浩一

Synthesis of porous γ-Fe<inf>2</inf>O<inf>3</inf> via alkaline treatment of size controlled scorodite particles synthesized using ultrasound irradiation and its evaluation as a cathode for lithium-ion battery

Yuya Kitamura, Hirokazu Okawa, Kozo Shinoda, Takahiro Kato, Katsuyasu Sugawara, Shigeru Suzuki

Japanese Journal of Applied Physics   58 ( SG )   2019年07月  [査読有り]

研究論文（学術雑誌）   国内共著

Herein, we synthesized scorodite particles using ultrasound irradiation in a strong sulfuric acidic solution (pH 0.5) and investigated the scorodite particles' size and morphology. The highest crystallinity of scorodite (96%) was synthesized using 200 kHz ultrasonic treatment, and maximum yield of scorodite was obtained in three conditions: 200, 28 kHz, and stirrer. The oxidant generated through 200 kHz ultrasound irradiation enhanced Fe(II) oxidation in the solution resulting in crystal nuclei formation. The crystal nuclei were transformed to scorodite by oxidation with a supply of solute [Fe(III)] from the solution and ostwald ripening. Clustered scorodite (4 μm in size) was obtained via synthesis using 200 kHz ultrasound (pH 0.5). Arsenic could be separated from the clustered scorodite via alkaline treatment; scorodite was changed to porous γ-Fe O comprising nanosized particles. Porous γ-Fe O was evaluated as a cathode in a lithium-ion battery, which showed a 149 mAh g discharge capacity with a 0.5 C rate. 2 3 2 3 -1

DOI

Effect of Ultrasound Irradiationon Deposition of Au nanoparticles on Carbon-coated cathode material

Yasuyuki Tanaka, Hirokazu Okawa, Yuki Ono, Turtogtokh Enkhtuya, Tsermaa Galya, Takahiro Kato, Katsuyasu Sugawara

JapaneseJournal of Applied Physics   58   SGGD17-1 - SGGD17-6   2019年06月  [査読有り]

研究論文（学術雑誌）   国内共著

Synthesis of Porous γ-Fe₂O₃ via Alkaline Treatment of Size Controlled Scorodite Particles Synthesized Using Ultrasound Irradiation and Its Evaluation as a Cathode for Lithium-Ion Battery₂

Yuya Kitamura, Hirokazu Okawa, Kozo Shinoda, Takahiro Kato, Katsuyasu Sugawara, and Shigeru Suzuki

JapaneseJournal of Applied Physics   58   SGGD03-1 - SGGD03-7   2019年06月  [査読有り]

研究論文（学術雑誌）   国内共著

Separation and Desulfurization of Bitumen from Oil Sand Using Oxidation Combined with Ultrasound

Hirokazu Okawa, Nobuyuki Akazawa, Takahiro Kato, and Katsuyasu Sugawara

JapaneseJournal of Applied Physics, 58, SGGD01-1-3 (2019)   58   SGGD01-1 - SGGD01-3   2019年05月  [査読有り]

研究論文（学術雑誌）   国内共著

LiFePO₄への金ナノ粒子の超音波合成およびその電池特性

大川浩一，小野裕貴，田中康之，加藤貴宏，菅原勝康

粉体工学会誌   56 ( 3 ) 117 - 122   2019年03月  [査読有り]

研究論文（学術雑誌）   国内共著

Sonochemical synthesis of au nanoparticles on lifePO4/C and the evaluation of its battery performance

Hirokazu Okawa, Yuki Ono, Yasuyuki Tanaka, Takahiro Kato, Katsuyasu Sugawara

Journal of the Society of Powder Technology, Japan ( 一般社団法人 粉体工学会 )  56 ( 3 ) 117 - 122   2019年03月  [査読有り]

研究論文（学術雑誌）   国内共著

LiFePO has attracted attention as a promising cathode material for lithium ion battery, because it consists of abundant elements. However, the battery performance of this material is limited by its low electron conductivity and low lithium ion diffusion rate. Coating its surface with an electronically conductive material, such as carbon, is one of the major methods to overcome this issue. In this study, we tried to synthesize Au nanoparticles (NPs) on the surface of carbon-coated LiFePO (LiFePO /C) using sonochemical reaction to further enhance the electron conductivity. The size of Au NPs deposited on the surface of LiFePO /C changed in relation to the concentration of Au ions. The battery performance of the Au NPs-deposited LiFePO /C, as evaluated at a high constant current rate of 20 C, showed an improvement in the polarization and discharge capacity of LiFePO /C. 4 4 4 4 4 4

DOI CiNii Research

Recovery of gold and silver from an incinerated spent printed circuit board using chlorination

Kosuke Sakusabe, Takahiro Kato, Hirokazu Okawa, Katsuyasu Sugawara

Journal of Chemical Engineering of Japan ( Journal of Chemical Engineering of Japan )  51 ( 8 ) 704 - 710   2018年08月  [査読有り]

研究論文（学術雑誌）   国内共著

<p>We studied an efficient recovery process for precious metals from secondary resources. The release behaviors of gold and silver were investigated during the heat treatment of an incinerated spent circuit board in a stream of chlorine gas. When the incinerated ash alone was heated in a stream of chlorine, a temperature of 1000°C was required to completely volatilize the gold and silver in the sample. However, the temperature required for the initial release of gold and silver decreased when a mixture of the incinerated spent printed circuit board and carbon particles was heated in a stream of chlorine, and fractions of these metals were captured by the carbon particles. The amounts of gold and silver captured by the carbon particles decreased when the temperature increased above 800°C. To completely volatilize the gold and silver from the sample and to ensure their capture by the carbon particles, the sample was heated to 1000°C in chlorine gas, and the volatilized chlorides were passed through a bed of carbon particles, which was maintained at 800°C. The total amounts of gold and silver from the incinerated printed circuit board were successfully recovered by adjusting the temperature and thickness of the bed of carbon particles.</p>

DOI

Simultaneous recovery and desulfurization of bitumen from oil sand using ultrasound irradiation

Okawa H.

Japanese Journal of Applied Physics ( Japanese Journal of Applied Physics )  57 ( 7 )   2018年07月  [査読有り]

研究論文（学術雑誌）  

DOI

Utilization of carbon dioxide to synthesize large scorodite particles under ultrasound irradiation

Yuya Kitamura, Hirokazu Okawa, Takahiro Kato, Katsuyasu Sugawara

Japanese Journal of Applied Physics   57   07LB15-1 - 07LB15-5   2018年06月  [査読有り]

研究論文（学術雑誌）   国内共著

Performance analysis of ZigBee network topologies for underground space monitoring and communication systems

Moridi, M.A.Email Author, Kawamura, Y., Sharifzadeh, M., Chanda, E.K., Wagner, M., Okawa, H.

Tunnelling and Underground Space Technology ( Tunnelling and Underground Space Technology )  71   201 - 209   2018年01月  [査読有り]

研究論文（学術雑誌）   国際共著

The advancement in tunnelling and underground space technologies and the need for large scale monitoring and communication systems for safe and efficient operations has triggered the era of wireless sensor networks (WSNs). The progress of WSNs have been associated with the innovation of sensor nodes with the more significant features of smaller size, more cost-effectiveness, lower latency and powerful antenna coverage. The sensor nodes arrangement in dense industrial WSNs is one of the crucial issues for a better quality of service and a reliable message transmission through the network. In this study, we investigate various sensor node arrangements of ZigBee networks for underground space monitoring and communication systems. The performance of ZigBee topologies are analysed in 12, 20, 30, 40 and 50-node scenarios for stationary node deployment in underground environments. The metrics used for the performance evaluation include throughput, packet delivery ratio (PDR), end-to-end delay, energy consumption and packet delivery security. The results evaluation confirms the mesh topology is prioritised in WSNs design considering higher throughput, packet delivery ratio and network security, while the cluster-tree topology is preferred in case of lower end-to-end delay and lower energy consumption. The analyses show that the mesh topology creates a more reliable monitoring and communication network with an adequate quality of service in underground spaces and tunnels. Therefore, greater end-to-end delay and energy consumption could not be major concerns for the mesh topology in underground mine applications based on the acceptable data latency and using mine power.

DOI

Utilization of ultrasonic atomization for dust control in underground mining

Hirokazu Okawa, Kentaro Nishi, Youhei Kawamura, Takahiro Kato, Katsuyasu Sugawara

Jpn. J. Appl. Phys   56   7JE10-1 - 07JE10-6   2017年06月  [査読有り]

研究論文（学術雑誌）   国内共著

Ultrasound-assisted oxidative desulfurization of bitumen

Wan Mohamad Ikhwan bin Wan Kamal, Hirokazu Okawa, Takahiro Kato, Katsuyasu Sugawara

Jpn. J. Appl. Phys.   56   07JE03-1 - 07JE03-3   2017年06月  [査読有り]

研究論文（学術雑誌）   国内共著

Effect of reaction temperature on the size and morphology of scorodite synthesized using ultrasound irradiation

Yuya Kitamura, Hirokazu Okawa, Takahiro Kato, Katsuyasu Sugawara

Ultrasonics Sonochemistry   35 ( PartB ) 598 - 604   2016年04月  [査読有り]

研究論文（学術雑誌）   国内共著

DOI

Recovery of Valuable Elements from Spent Printed Circuit

Takahiro Kato, Katsuyasu Sugawara and Takashi Nakamura

Journal of Chemical Engineering of Japan   49 ( 1 ) 60 - 67   2016年01月  [査読有り]

研究論文（学術雑誌）   国内共著

Desorption of CO2 from low concentration monoethanolamine solutions using calcium chloride and ultrasound irradiation

Kosuke Tanaka, Hirokazu Okawa, Tatsuo Fujiwara, Takahiro Kato, Katsuyasu Sugawara

Japanese Journal of Applied Physics   54   07HE08 - 07HE08   2015年07月  [査読有り]

研究論文（学術雑誌）   国内共著

Ultrasound Irradiation for Desorption of Carbon Dioxide Gas from Aqueous Solutions of Monoethanolamine

Kosuke Tanaka, Tatsuo Fujiwara, Hirokazu Okawa, Takahiro Kato, Katsuyasu Sugawara

Japanese Journal of Applied Physics   53 ( 7S ) 07KE14-1 - 07KE14-5   2014年07月  [査読有り]

研究論文（学術雑誌）   国内共著

超磁歪振動子を利用した極浅層における地中映像化システムに関する研究

蒲原章裕、川村洋平、鎌形真伍、大川浩一

Journal of MMIJ   127 ( 4, 5 ) 182 - 188   2011年01月

研究論文（学術雑誌）  

Recovery of Bitumen from Oil Sand by Sonication in Aqueous Hydrogen Peroxide

Hirokazu Okawa, Tomonao Saito, Ryota Hosokawa, Takashi Nakamura, Youhei Kawamura, and Shinobu Koda

Jpn. J. Appl. Phys.     2011年01月

研究論文（学術雑誌）  

Effect of Ultrasound Irradiation on Arsenic Adsorption from Aqueous Solution into Iron Compound

Ryota Hosokawa,Tomonao Saito,and Hirokazu Okawa

Jpn. J. Appl. Phys.     2011年01月

研究論文（学術雑誌）  

Effects of different ultrasound irradiation frequencies and water temperatures on extraction rate of bitumen from oil sand

Hirokazu Okawa, Tomonao Saito, Ryota Hosokawa, Takashi Nakamura, Youhei Kawamura, and Katsuyasu Sugawara

Jpn. J. Appl. Phys.   49 ( 2 ) 07HE12 - 1   2010年01月

研究論文（学術雑誌）