FeCl_3存在时六六六热解生成PCDD/Fs的研究

在开管体系中,于280℃时研究了六六六无效体在Fe,理体制FeCl_3存在时的热解,以及影响热解产物中PCDD/Fs生成量的因素.PCDD/Fs的生成主要取决于FeCl_3,而Fe的存在并不增加体系中PCDD/Fs的生成量.在封管体系中,研究结果表明PCSS/Fs的生成量随FeCl_3用量、反应时间和反应温度的增加而增加,但温度影响最大.实验还表明,氯苯、氨酚对PCDD/Fs的生成起决定作用.在250─280℃,PCDD/Fs的生成主要在于二者之间的缩合,而单独氯酚间的缩合则居次要地位.氯化对生成PCDD/Fs的种类及量影响很大.250─280℃时,低氯苯、氨酚在FeCl_3作用下氯代成高氯产物,进而缩合成 OCDD/F;但在 350℃以上时,氯酚反应活性增加,故低氯PCDD/Fs生成量增加,OCDD/F生成量相对降低.     

六六六热解废渣提取物对家兔皮肤的毒性

使用六六六热解废渣提取物对家兔进行了皮肤毒性试验。家兔皮肤经涂布提取物后,在涂布处及其他部位引起常有丘疹和小脓疱特征的痤疮型皮炎,与六六六热解生产多氯苯时暴露于其废渣烟尘中的工人所患氯疮相似。分析证明废渣中含有大量PCDDs和PCDFs,显然这是家兔皮肤反应和工人皮肤疾患的原因。引起家兔皮肤反应的最小涂布剂量为55μg混合物质,其中含2,3,7,8-TCDD约0.003μg。     

六六六热解废渣中2,3,7,8—取代PCDDs和PCDFs的测定

采用ＨＰＬＣ和ＧＣ／ＭＳ法对六六六热解废渣中的ＰＣＤＤｓ和ＰＣＤＦｓ进行了测定，使用此种方法，于废渣中检出了所有２，３，７，８－取代的同系物。此外，还根据各ＣＤＤｓ，ＣＤＦｓ的毒性当量因子ＴＥＦｓ，计算了废渣的毒性当量ＴＥＱｓ，约为６１２－９２４μｇ／ｇ。分析表明，ＯＣＤＤ是含量最丰富的导构体，而１，２，３，４，６，７，８－ＨｐＣＤＤ，１，２，３，４，６，７，８－ＨｐＣＤＦ和１，２，３，４，７，８     

Detailed analysis of PCBs and PCDD/Fs impurities in a dielectric oil sample （ASKAREL Nr 1740） from an imported transformer in China

Homolog and congener profiles of polychlori- nated biphenyls （PCBs）, polychlorinated dibenzo-p- dioxins （PCDDs） and polychlorinated dibenzofurans （PCDFs） in commercial PCBs formulations are useful information for the source appointment of PCBs contam- ination as well as the risk assessment caused by potential exposure. Dielectric oil （ASKAREL Nr 1740） in an imported transformer found in China was sampled and analyzed by isotope dilution technology using high resolution gas chromatography-high resolution mass spectrometry （HRGC/HRMS）. The detailed homolog and congener profiles of PCBs obtained were compared with those of known Aroclor formulations. High similarity in the homolog profile between the oil sample and Aroclor 1260was found, with the hexachlorinated and hepta- chlorinated biphenyls accounting for more than 80.2% of the total PCBs concentration. Severn indicator PCBs contribute about 30%, while 12 PCB congeners （i.e., # 153, #143, #168, #180, #149, #165, #138, #170, #190, #187, #174, #181） account for more than 50% of the total PCB concentrations. Total concentration ofPCDDs, PCDFs and dioxin-like PCBs （DL-PCBs） was found to be 740 ng TEQ/g, of which 620 ng TEQ/g came from DL-PCBs. The contribution of PCDDs to the total TEQ was neglectable. The concentration of PCDFs homologs follows the order of OCDF 〉 HxCDFs 〉 HpCDFs 〉 PeCDFs 〉 TeCDFs, which is in consistence with the previous study on Aroclor 1260. Three DL-PCBs congeners （i.e., #118, #156, #157） accounted for 77% of the total concentration of DL-PCBs, also they contribute 72% in the TEQ caused by DL-PCBs.     

分子电性距离矢量用于多氯代二苯并呋喃光解半衰期的QSPR研究（Molecular Electronegativity Distance Vector（MEDV）Applied to Quantitative Structure-Property Relationship Study on Photolysis Half-Lives of PCDFs）

多氯代二苯并呋喃(PCDFs)是一种典型的持久性有机污染物(POPs),光解是其在环境中转化的主要途径.以分子电性距离矢量(Molecular Electronegativity Distance Vector,MEDV)为参数,应用多元线性回归(Multiple Linear Regression,MLR)和偏最小二乘回归(PLSR)对48种PCDFs在云杉针叶和飞灰表面的光解半衰期(t1/2)进行模拟分析,均获得由2个变量所建的定量结构-性质相关(QSPR)模型.多元线性回归结果:建模相关系数(R)分别为0.860和0.836,标准偏差(SD)分别为0.052和0.053,交互检验复相关系数(Rcv)分别为0.839和0.807,外部检验相关系数(Qex)t分别为0.939和0.853;偏最小二乘回归结果:建模相关系数(R)分别为0.857和0.829,交互检验复相关系数(Rcv)分别为0.849和0.807.结果表明,MEDV能较好地表征该类分子的结构信息,所建QSPR模型具有良好的稳定性和预测能力.