高稳性碘代X-射线造影剂在饮用水消毒过程中的降解与I-DBPs产生特性

Iodinated X-ray contrast media (ICM) are widely used in clinical imagining for soft tissue. With stable chemical resistance and strong hydrophilicity, these pharmaceutical residuals can be frequently detected in source waters. Since the parent ICMs shows quite low toxicity to humans, the adverse effects of ICMs are always ignored in water environments. However, ICMs received great attention recently due to their transformation and formation of extreme toxic Iodinated disinfection by-products (I-DBPs) during water disinfection. Based on previous studies, five widely detectable ICMs including iopamidol were selected in this proposal. Fate and degradation pathways of these typical ICMs in disinfection treatment of drinking water will be investigated including: (1) to investigate the ICMs degradation during chlor(am)ination process. The degradation kinetics, pathways and intermediates will be built and identified; (2) to discover the formation of I-DBPs during ICMs chlor(am)ination. The effects of coexistence of dissolved organic matter (DOM) will be clarified; (3)to study the ICMs degradation during UV irradiation. The change of I-DBPs formation potentials will be investigated as well. (4) to assess the combination process of UV irradiation and chlorination during ICMs degradation. As shown above, the reliable and integrated theory of ICMs removal and I-DBPs control in water treatment will be presented in this project.

碘代X-射线造影剂（ICM）广泛应用于临床软组织成像，具有分子结构稳定、亲水性极强等特点，是水源中最容易医药残留化合物种类之一。鉴于ICM本体毒性较低，其危害常被忽视。近来发现ICM与水处理常用消毒剂发生反应，是导致极强“三致”碘代消毒副产物（I-DBPs）产生的关键途径之一，其安全性逐步得到关注。课题将在前期研究的基础上，以水源检出率最高的碘帕醇等5种ICM为研究对象，重点开展其在饮用水消毒工艺中的转化机制和I-DBPs产生特性研究。探索ICM氯(胺)化降解规律，构建动力学模型，辨析其降解途径和产物；明晰共存溶解性有机物的作用机制，揭示ICM氯(胺)化过程中I-DBPs生成规律；探究紫外消毒中ICM脱碘新机理，掌握紫外照射后I-DBPs生成潜能变化规律；探明紫外/氯组合工艺降解ICM的效能，获得有效的技术方法；最终为净水工艺中ICM消减与I-DBPs控制，提供可靠的理论支持。

水中广泛存在的碘代X-射线造影剂（ICM）易与消毒剂发生反应生成强“三致”碘代消毒副产物（I-DBPs），其安全性逐步得到关注。本课题以ICM在消毒过程中的降解规律、转变机制与风险削减为主要研究重点，系统开展了氯（胺）消毒过程中ICM的降解特性、共存有机物条件下ICM氯（胺）化过程I-DBPs生成规律、紫外辐照下ICM脱碘规律与后续消毒过程中I-DBPs生成特性、紫外/氯等高级氧化降解ICM及I-DBPs生成风险削减方法探索等研究工作，同时拓展了臭氧氧化、基于硫酸根自由基高级氧化降解ICM的特性等内容。课题研究了5种典型ICM在自由氯和氯胺氧化过程中的降解特性，求算获得了其表观和基元反应速率常数，掌握了其反应动力学规律、中间产物与降解机制，发现ICM分子结构非常稳定，与自由氯和一氯胺的反应活性较低，其侧链基团对反应活性影响较大；通过水中溶解性有机物对ICM氯（胺）化生成I-DBPs的影响分析，发现藻类有机物（AOM）背景生成I-DBPs远高于腐殖质、富里酸类有机物背景，原水中极性小分子组分DOM在ICM氯（胺）化反应体系I-DBPs产率明显更高；紫外光对各种ICM的降解速率较快，降解反应过程符合拟一级动力学模型，得出了ICM的量子产率和紫外降解ICM的表观速率常数，明确了ICM的降解途径与脱碘机制，并阐明了后续消毒中转化产生I-DBPs的产率与变化规律；紫外/氯高级工艺是高效降解ICM和削减I-DBPs生成的技术方法，研究建立了相关的降解效能模型，求算了相关的速率常数，分析获得了反应体系中羟基自由基、光降解、氯自由基等对ICM降解的贡献，也阐明了体系中不同碘形态的变化特征和ICM的降解与矿化规律，掌握了I-DBPs生成潜能的变化特性与重要影响因素；同时也系统研究了基于不同激发方式的硫酸根自由基、臭氧氧化的高级氧化工艺去除ICM的效能与规律。研究成果可以为净水工艺中ICM消减与I-DBPs控制，提供可靠的理论支持。