碱催化水热氧化处理氯代有机物污染土壤的自由基反应及作用机理研究

The green and efficient treatment technology of chlorinated organic contaminated soil become an international concern. In the previous study, it was found that the addition of basic catalyst could promote the formation of free radicals, which can significantly reduce the reaction conditions of hydrothermal oxidation (HTO) with chlorinated organic pollutants in soil. However, the initiation process of free radicals and the degradation mechanism of chlorinated organic pollutants in contaminated soil needs further analysis. The representative chlorinated organic pollutants will be used in alkali-catalyzed hydrothermal oxidation system to promote dechlorination degradation of chlorinated organic pollutants in contaminated soil. The effects of different basic catalysts on the free radicals will be investigated. Considering the effects of different soil components on free radical production, removal efficiency and dechlorination efficiency of representative chlorinated organic pollutants, the interaction mechanism between chlorinated organic pollutants and main components of soil will be elucidated. Based on non-Fick diffusion theory and power function equation, reaction kinetics model of chlorinated organic pollutants in contaminated soil under alkali-catalyzed HTO process will be obtained. Considering the time-varying characteristics of chlorine-containing products, the degradation path and mechanism of chlorinated organic pollutants in contaminated soil will be revealled, and the degradation path map of free radical dechlorination process will be also summaried. Moreover, optimized process parameters of chlorinated organic pollutants in contaminated soil under alkali-catalyzed HTO process will be established. Through the study of these scientific problems, it will lay a theoretical foundation for deep understanding of the degradation mechanism of HTO treatment for chlorinated organic pollutants in soil and the practical application of this technology.

氯代有机物污染土壤的绿色处理与修复是国际上关注的焦点问题。申请人前期研究发现，碱催化剂引入可以促进自由基的生成，有效降低水热氧化（HTO）处理氯代有机污染物的反应条件，但自由基的引发过程及其对土壤中氯代有机污染物的催化降解机制尚需进一步解析。本申请拟开展碱催化HTO处理氯代有机物污染土壤的自由基反应及作用机理研究。考察不同碱催化剂对自由基生成情况的影响，查明不同碱催化剂对自由基引发机制及降解过程的影响。根据不同土壤组分对自由基产生及脱氯效率的影响结果，阐明氯代有机污染物与土壤组分之间的交互作用机制。基于非Fick扩散理论和幂函数型方程，建立反应动力学模型，结合含氯产物的时间变化特征，揭示自由基降解机理，绘制自由基脱氯降解路径图。借助响应面设计方法优化工艺参数，确立碱催化HTO处理氯代有机物污染土壤的技术方法，为深层次认知HTO降解土壤中氯代有机污染物的机理及该技术的应用奠定理论基础。

土壤中氯代有机污染物的绿色无害化处理是土壤有机污染修复领域面临的热点关注问题，水热氧化（HTO）技术对有机污染物处理具有效率高、选择性广和环境友好等优点。本项目以水土环境介质中氯代有机污染物的高效脱氯为研究目标，选取三氯生（TCS）作为典型氯代有机污染物，采用碱催化HTO对水和土壤介质中的TCS进行脱氯降解研究。获得以下结论：.（1）在碱催化HTO处理水中TCS的方法与机理研究中发现，对脱氯效率影响较显著的反应参数是H2O2/TCS比、反应温度和停留时间，最佳条件下脱氯效率为99.26%。TCS的脱氯动力学符合准一级动力学模型。推断碱催化HTO处理水中TCS可能的降解途径：1）苯环发生羟基化反应，再氧化开环后逐级脱氯。2）TCS分子结构的C-O断裂，苯环发生开环反应，再氧化脱氯。最后，产生的中间降解产物进一步氧化后完全脱氯。.（2）在碱催化HTO过程中TCS与土壤主要组分交互作用机制研究中发现，土壤无机矿物和有机质组分均抑制TCS的降解脱氯过程，无机矿物组分的抑制作用弱于有机质组分。获取四种土壤组分下TCS的共性降解产物为多氯苯环产物、含C=O的无氯多苯环产物以及羟基苯甲酸。.（3）在碱催化HTO处理TCS污染土壤的自由基脱氯路径和技术研究中发现，•OH参与了土壤中TCS的脱氯降解过程并起到控制作用，同时•OH参与程度越高，对应的脱氯效率也越高。结合降解产物3D-EEM和GC-MS分析结果，推断并绘制了自由基脱氯降解路径图。蛋白核小球藻毒性测试结果表明，实际土壤中TCS处理后的毒性显著降低。.通过以上研究的结果，可以为水土环境介质中氯代有机污染物的高效绿色降解提供有价值的技术方法和理论支持。