Atsushi Ohara

Measurement of temperature dependence for the vapor pressures of twenty‐six polychlorinated biphenyl congeners in commercial Kanechlor mixtures by the Knudsen effusion method

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.

Vapor pressure of ten polychlorinated biphenyl congeners and two commercial fluids as a function of temperature

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.

A Study on the Effective Management by the Quality Control Technique Concerning the PCB Detoxification Plant

PCB処理施設の設置許可期間短縮を事例とし, 品質管理の手法の一つであるDMAIC法 (Define: 定義, Measure: 計測, Analyze: 解析, Improve: 改善, Control: 実行管理) の5段階法を用いて設置許可の手順を定量化し, 事業管理の効率化に関し以下の成果を得た。最初に, 設置許可手続き期間 (申請書の受理日から専門家会議の終了日までの期間: Lead Time: LT) の目標値からの遅延を最小化することを定義し, LTの遅れ, 欠陥率R (%) を定義した。次に特性要因図を作成し, 専門家会議手続きの遅延要因分析のため故障モード影響解析を実施した。さらに, 専門家会議の進行段階の19ステップすべてに定量化した故障の影響度 (Severity: SEV) と故障の発生のし易さ (Occurrence: OCC) および故障の発見のし易さ (Detection: DET) の積 (SEV×OCC×DET) をリスク度 (Risk Priority Number: RPN) と定義し定量化し, RPN評価を基に, 影響度に応じてリスク防止の推奨策 (Actions Recommended: AR) を提案し, ARを実行した。最後に, 第1回専門家会議終了後から第2回専門家会議終了時点までARを実行した。第2回専門家会議終了時点で, 19項目のすべてのRPNは120未満となり, 結果的に専門家会議は3回で終了し設置許可が取得できた。結論として, 従来約10か月を要していたLTを最終的に4.5か月に短縮しR=15%を達成した。