Tomohiro Todoroki
Toshiba
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Featured researches published by Tomohiro Todoroki.
Chemosphere | 2010
Takeshi Sato; Tomohiro Todoroki; Kimiaki Shimoda; Akihiko Terada; Masaaki Hosomi
Thermal desorption is an effective method for removing volatile and semivolatile organic matter in contaminated solid remediation. Formation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in many polychlorinated biphenyls (PCBs) destruction processes has been reported, but the removal pathways are poorly understood. We therefore investigated the behaviors of PCBs and PCDDs/PCDFs in thermal desorption of PCBs-contaminated sediment and predicted the reaction pathways. Four thermal desorption experiments using PCB-contaminated sediments containing different doses of PCBs were carried out. In all the experiments, decomposition of 48-70% of PCBs was achieved, resulting in formation of PCDFs. Despite the PCBs decomposition levels, toxic equivalencies (TEQs) in the treated and volatilized samples were 2.8-6.3 times and 8.0-10.5 times as high as the TEQs in the initial samples, respectively, indicating increased toxicity after treatment. Further analysis revealed that PCDFs with higher numbers of chlorine atoms are likely to remain in the sediments than those of volatilized PCDFs; this is supported by the positive correlation between the vapor pressures of PCDFs and the ratios of volatilized PCDFs.
Environmental Toxicology and Chemistry | 2006
Katsuhiko Nakajoh; Etsuro Shibata; Tomohiro Todoroki; Atsushi Ohara; Katsushi Nishizawa; Takashi Nakamura
The vapor pressures of the major congeners in commercial polychlorinated biphenyl (PCB) mixtures (Kanechlors; Kanebuchi Chemical Industry, Tokyo, Japan) have been experimentally determined by Knudsen mass loss effusion. We obtained vapor pressures for the individual PCBs in the crystalline solid, liquid, and subcooled liquid forms as a function of temperature. We derived the thermodynamic parameters, such as the enthalpies of sublimation and vaporization, from the temperature dependence of the vapor pressure by the Clausius-Clapeyron equation. To decide whether the commercial PCB mixtures were ideal solutions, we obtained the activity coefficients by comparing our experimental vapor pressures for pure PCB congeners with those calculated from Kanechlor molar compositional data and vapor pressure values. In many cases, we found that, at 298 K, the values of the activity coefficients of major PCBs in Kanechlor 300 and 500 ranged from 1 to 2. Thus, we suggested that the commercial PCB mixtures show slight positive deviations from ideal solution (Raoults Law) behavior at ambient temperatures.
Environmental Toxicology and Chemistry | 2005
Katsuhiko Nakajoh; Etsuro Shibata; Tomohiro Todoroki; Atsushi Ohara; Katsushi Nishizawa; Takashi Nakamura
The Knudsen mass-loss effusion technique was used to measure the vapor pressures of commercial Kanechlor fluids (Kanechlor 300 and Kanechlor 500) and 10 major individual polychlorinated biphenyls (PCBs) in Kanechlors as a function of temperature and ortho-chlorine substitution. From the temperature dependence of vapor pressure, the thermodynamic parameters, such as enthalpies and entropies of sublimation and vaporization, were derived using the Clausius-Clapeyron equation. The results were compared with both experimental and calculated literature values. The ortho-chlorine substitution effects on the vapor pressure of major PCB congeners in Kanechlor mixtures were studied on the same homologous series. Within this series, the greater the number of chlorine substitutions in the ortho-positions, the higher the vapor pressure, because of the ortho-effect.
Archive | 2003
Katsuhiko Nakajoh; Takehiko Muramatsu; Yukishige Maezawa; Masao Kon; Tomohiro Todoroki; Katsushi Nishizawa; Atsushi Ohara
Archive | 1997
Kouichi Teshima; Tomohiro Todoroki; Terunobu Hayata; Fuminobu Tezuka; Masao Koyama; Naohiko Oyasato; Tomiaki Furuya; Yoshiaki Yokoyama; Teruhisa Ogihara; Kaichiro Ogihara
Archive | 1995
Terunobu Hayata; Tadao Machida; Takumi Oikawa; Miya Sasaki; Fuminobu Tezuka; Tomohiro Todoroki; Tatsuya Tsuda; Yuka Yoda; 美弥 佐々木; 由佳 依田; 巧 及川; 史展 手塚; 輝信 早田; 達也 津田; 忠男 町田; 朋浩 轟木
Archive | 1996
Terunobu Hayata; Tomohiro Todoroki; 輝信 早田; 朋浩 轟木
Archive | 2008
Yuka Hiraga; Takeshi Sato; Satoshi Suzuki; A. Tanaka; Tomohiro Todoroki; 岳史 佐藤; 夕佳 平賀; 淳 田中; 朋浩 轟木; 聡 鈴木
Archive | 1997
Yoshiaki Yokoyama; Teruhisa Ogihara; Koichi Teshima; Tomohiro Todoroki; Terunobu Hayata; Fuminobu Tezuka; Masao Koyama; Naohiko Oyasato; Tomiaki Furuya; Kaichiro Ogihara
Archive | 2007
Yoshiaki Yokoyama; Teruhisa Ogihara; Koichi Teshima; Tomohiro Todoroki; Terunobu Hayata; Fuminobu Tezuka; Masao Koyama; Naohiko Oyasato; Tomiaki Furuya; Kaichiro Ogihara