Fe(VI)降解水中颗粒物表面邻苯二甲酸酯类化合物的机制及QSAR研究

Phthalate esters (PAEs), a group of endocrine disrupting compounds, have attracted the scientific and public attention, because they are widely used and considered as ubiquitous environmental pollutants. Once released into the water environment, PAEs tend to be adsorbed on suspended particles or sediments due to their strong hydrophobicity. Therefore, it is necessary to develop efficient treatment methods to eliminate PAEs adsorbed onto solid particles in water. In this project, ferrate (Fe(VI)) has been selected as the oxidizing agent to study the kinetics, reaction mechanism and toxicity changes of PAEs. After the detailed characterizations of solid particles, the adsorption behavior between 25 PAEs and suspended particles and sediments is examined in natural water, and a series of kinetic experiments are carried out to study the influence of various factors on PAEs removal. Modern analytical techniques are employed to identify the degradation products. Combining the relevant theoretical calculation and experimental results, the Fe(VI)-mediated reaction mechanism of PAEs is proposed. The QSAR model between molecular structure parameters and reaction rate constants is established to reveal the main molecular descriptors affecting the reaction rate. The toxicity changes of degradation products are evaluated according to toxicology tests and identification of intermediate products. This project provides new insights and references for the transformation, removal and potential ecological risks of PAEs in the actual environment.

邻苯二甲酸酯(PAEs)具有环境激素效应，已被公认为是全球性污染物。鉴于其较强的憎水性，释放到水体中的PAEs通常会吸附在悬浮颗粒物或沉积物表面，因此，利用一种高效的技术去除水中吸附在颗粒物表面的PAEs至关重要。本项目拟采用新型水处理氧化剂高铁酸盐(Fe(VI))处理PAEs，对其动力学、降解机理和毒性变化进行系统地研究。在表征颗粒物的基础上，考察25种PAEs与天然水体中悬浮颗粒物和沉积物之间的吸附行为，进一步探讨一系列的实验条件对PAEs降解速率的影响；采用现代分析技术，鉴定中间产物结构，并结合量子化学计算，阐明Fe(VI)降解PAEs的反应机制；构建25种PAEs的降解速率常数和分子结构参数之间的QSAR模型，从分子结构层面揭示影响降解速率的主要因素；借助毒理学检测手段，综合产物鉴定，评价降解产物的毒性变化。本研究可为实际环境中PAEs的转化、去除及潜在的生态风险提供新见解和参考。

近年来，高铁酸盐（Fe(VI)）以及零价铁在处理有机污染物方面的应用越来越广泛。人们对于其研究不再局限于其对目标底物的去除率大小，而是对它们的氧化机理展开了深入的讨论。主要考察了高铁酸盐降解双氯酚(DCP)、邻苯二甲酸二乙酯(DEP)以及Fe0催化PMS降解负载于石英砂 (QS) 表面的邻苯二甲酸二丁酯(DBP)的动力学和反应机理研究。首先，研究了Fe(VI)对水环境中双氯酚以及土壤颗粒物表面DEP的处理效果。系统考察了氧化剂量、土壤类型、pH值以及无机离子等对Fe(VI)降解两种化合物效率的影响。采用液质联用技术（LC-MS）和理论计算对两种化合物在氧化过程中可能出现的中间产物进行了分析，推测出三种化合物可能的降解路径，主要包括羟基化反应、耦合反应以及桥键断裂三个过程。为了将过渡金属/PMS技术应用在土壤环境中，研究了Fe0/PMS技术在酸性环境中对石英砂 (QS) 等颗粒物表面吸附的DBP的降解动力学及机理。这些工作为高铁酸盐以及过渡金属活化PMS技术在水或土壤污染控制过程的高效应用、活性物质的生成调控及有机污染物的生态风险管控等相关工作提供了技术指导和科学支撑。