Physicochemical Study of the Formation and Decomposition of Organohalogen Compounds

本研究的目的是鉴定和确定有机卤素化合物，如多氯二苯并对二恶英/呋喃和多溴二苯并对二恶英/呋喃的物理化学性质。利用有机卤素化合物的物理化学性质，可以预测其生成和分解行为。1.采用Knudsen渗出法测定了PCDD/Fs、OBDD、Kanechlor 300和BFR的蒸气压。设计了一种用于二恶英同系物和其他持久性有机污染物蒸气压测量的小型努森池装置。用参比化合物对装置进行了标定，并将蒸气压结果与现有的参比数据进行了比较。利用努森池进行了吸附实验。测定了氢氧化钙、赤铁矿、石墨和活性炭与OCDD的表观蒸气压。用差示扫描量热仪测定了DD、DF、OCDD和OCDF的固相热容、熔点和熔点。采用分子轨道方法和密度泛函理论计算了PCDD/Fs气相的热容、熵和标准生成焓等热力学函数。根据实验数据和文献数据，估算了DD、DF、OCDD和OCDF在固相到气相范围内的生成焓随温度的变化关系。3.利用密度泛函理论和统计热力学理论计算了PBDD/Fs的热力学性质（热容、熵、焓和生成吉布斯自由能）。所采用的方法进行了评估，使用溴代芳烃化合物的实验热力学数据。

The purpose of this study is to qualify and establish the physicochemical properties of organohalogen compounds such as PCDD/Fs and PBDD/Fs. The formation and decomposition behaviors of the organohalogen compounds can be estimated using their physicochemical properties.1.Determinations of vapor pressure of PCDD/Fs, OBDD, Kanechlor 300 and BFRs using Knudsen effusion methods. A new apparatus with a very small Knudsen cell was especially designed for the vapor pressure measurements of dioxin congeners and other POPs. The apparatus was calibrated by reference compounds, and the vapor pressure results were compared with the available reference data. The adsorption experiments were also carried out by mean of Knudsen cell. The apparent vapor pressures of OCDD with calcium hydroxide, hematite, graphite and activated carbon were measured. The adsorbing abilities of these compounds were estimated from the apparent vapor pressures of OCDD.2.Heat capacities of solid phase, melting points and enthalpies of fusion for DD, DF, OCDD and OCDF were measured by a modulated differential scanning calorimeter. Thermodynamic functions of gas phase such as heat capacity, entropy and standard enthalpy of formation for PCDD/Fs were calculated by the molecular orbital method with density functional theory. The temperature dependences of enthalpies of formation for DD, DF, OCDD and OCDF were estimated in the range from the solid phase to the gas phase using the data obtained in this study and reference data.3.Thermodynamic properties (heat capacity, entropy, enthalpy and Gibbs energy of formation) of PBDD/Fs were calculated by Density function theory and statistical thermodynamics theory. The employed methods were evaluated using brominated arenes compounds with experimental thermodynamic data.