PVC水热脱氯过程中氯形态分布及迁移特性研究

Hydrothermal dechlorination is one of the most important ways to prevent the generation of dioxins and polychlorinated biphenyls carcinogenic substances, and also to avoid the high temperature chlorine corrosion of equipment during the incineration of chlorinated organic wastes. It is fundamental to explore the chlorine distribution and transformation characteristics during hydrothermal dechlorination of PVC in the field of engineering thermophysics and solid wastes to energy. By means of some morphological characterizing and measurement techniques, this work will focus on: 1) investigating the effect of operating parameters on the hydrothermal dechlorination efficiency and finding out the key operating parameter affecting the chlorine removal efficiency; 2) detecting the existing form and distribution of chlorine during hydrothermal dechlorination of PVC, and building the corresponding dynamics model to describe the chlorine transformation characteristics; 3) exploring the internal connection between the apparent phenomenon and operating parameters, molecular weight, C/Cl/O functional groups of PVC; (4) studying on the quantitative description of chlorine transformation by fully considering the nucleophilic substitution, ionic chain reaction and dehydration during hydrothermal dechlorination of PVC, and elaborating the chlorine transformation characteristics from the viewpoint of chemical reaction pathway during hydrothermal dechlorination of PVC; (5) studying on the role of additives by adding some chemicals such as CaO, NaHCO3, NaOH, KOH, NH3·H2O and H2O2 into the hydrothermal dechlorination of PVC. This work has some theoretical significance to optimize the operating parameters in order to improve the hydrothermal dechlorination efficiency of chlorinated wastes and to reveal the mechanism of hydrothermal dechlorination process.

水热脱氯是解决含氯废物焚烧过程中二噁英、多氯联苯类致癌物质的产生，及设备高温氯腐蚀的重要途径之一，探索水热脱氯过程中氯形态分布及迁移特性是工程热物理和固废能源化利用领域重要的基础研究内容。借助形态结构表征技术，研究：1）PVC水热条件对脱氯效率的影响规律，揭示影响PVC水热脱氯的关键因素；2）PVC水热脱氯过程中氯的存在形态及分布特征，建立PVC水热脱氯过程中氯迁移动力学模型；3）PVC含碳/氯/氧官能团结构、分子量及稳定剂种类对氯脱除的影响规律，揭示内在作用机制；4）亲核取代、化学脱水、离子连锁反应协同作用下的PVC水热脱氯过程中氯迁移的定量描述，从PVC水热脱氯化学反应历程的角度揭示PVC水热脱氯过程中氯迁移规律；5）以氧化钙、碳酸氢钠、氢氧化钠、氢氧化钾、氨水、双氧水等为调节剂，研究其在PVC水热脱氯中的作用机制。项目结果对优化提高水热脱氯效率和揭示水热脱氯过程机制有重要的理论意义。

本项目以PVC水热脱氯过程中氯形态分布及迁移特性为研究对象，选取3种结构性质不同的PVC，借助SEM、FTIR、XPS及13C NMR等技术手段，研究了：1）PVC水热脱氯条件对脱氯效率的影响规律，揭示影响PVC水热脱氯效率的关键因素；2）PVC水热脱氯过程中氯的存在形态及分布特征，建立PVC水热脱氯过程中氯迁移动力学模型；3）PVC水热脱氯表观现象与水热条件、样品分子量、碳氯官能团结构特征等的内在关联，从PVC水热脱氯化学反应历程的角度揭示PVC水热脱氯过程中氯迁移规律；4）以氧化钙、碳酸氢钠、氢氧化钠、氢氧化钾、氨水、双氧水等为调节剂，研究其在PVC水热脱氯中的作用机制。在此基础上，提出了高碱固体燃料与含氯塑料协同水热碳化的高效脱氯措施，同步去除有害元素的工艺，协同水热提质后水热炭性能优异，可作为处理焦化废水的吸附材料，可同步产氢，氢气/一氧化碳的比值高达3.0。项目研究成果可为含氯有机废物水热脱氯操作条件和调节剂的选择提供依据，实现有机固废的高效清洁回收，协同水热提质可丰富和发展有机废物处理理论。课题始终围绕项目申请书开展，超额完成了申请书的所有研究内容和成果指标。