碳纳米材料在水处理消毒剂作用下的转化机制及其效应研究

With the rapidly increasing and widespread use of carbon nanomaterials (CNMs), they were inevitably released into the environment. Water treatment system is the final step to prevent CNMs enter into the human body, therefore, it is really important to understand the transformation and environmental fate of CNMs during water treatment processes. Many carbon nanomaterials (such as functionalized carbon nanotubes, graphene oxide, etc.) were really active in water system and may react with different kinds of disinfectant in water treatment systems, resulting in their physicochemical transformation, and affecting their environmental behavior and toxicity effects. The project will focus on carbon nanotubes, graphene oxide and graphene nanoplatelets during the disinfection process (with chlorine disinfection, ozone disinfection, etc.), analyzing their physicochemical characters and effects under the effect of disinfectants, revealing the relationship between CNMs’ physicochemical properties and their transformation pathway and mechanisms. Meanwhile, it is also really important to understand their effects for environmental behaviors through aggregation, transportation, sedimentation and toxicity experiments. The results of this research will provide evidence for further exploring the environmental behavior and effects of nanomaterials.

随着石墨烯和碳纳米管等人工碳纳米材料的大量生产和使用，这些材料将不可避免地通过多种渠道进入环境中。水处理系统是阻断这些材料人体暴露的最后屏障，因此，理解碳纳米材料在水处理工艺中的转化和归趋至关重要。许多碳纳米材料（如官能化碳纳米管、氧化石墨烯等）性质较为活跃，可在水处理系统中各类消毒剂作用下发生转化，导致其理化性质发生改变，进而影响碳纳米颗粒自身的环境行为和毒性效应。本项目拟针对水处理过程中氯消毒、臭氧消毒等典型消毒流程对碳纳米管、氧化石墨烯和石墨烯纳米片等碳纳米材料的转化开展研究，通过各种理化表征手段，分析碳纳米材料在消毒剂作用下的物理形态及化学组成的变化，揭示碳纳米材料理化性质与其化学转化路径和机制的内在联系。同时，通过胶体稳定性和沉积实验、迁移实验及细胞毒性实验，明确碳纳米材料转化对其在团聚沉降、迁移归宿以及生物毒性的影响机制，为进一步揭示人工纳米材料的环境行为和效应提供理论依据。

随着大量碳纳米材料的生产和使用，这些碳材料将不可避免地通过多种渠道进入环境中，其潜在的环境风险受到广泛关注。许多碳纳米材料（如官能化碳纳米管、氧化石墨烯等）性质较为活跃，可在水处理系统中各类消毒剂作用下发生转化，导致其理化性质发生改变，进而影响碳纳米颗粒自身的环境行为和毒性效应。本项目针对水处理过程中氯消毒、臭氧消毒等典型消毒流程对碳纳米管、氧化石墨烯和石墨烯纳米片等碳纳米材料的转化展开研究，并揭示碳纳米材料理化性质与其化学转化路径和机制的内在联系。研究表明，氯消毒和氯胺消毒后，C=O含量减少，–C–OH/O–C–O含量增加，同时氯加成取代到氧化石墨烯上；而臭氧消毒处理后，部分石墨烯基底被氧化，环状结构被破坏，部分O–C–O和C=O转换成–COOH，其形态结构也发生了变化。此外，研究结果表明，同时光照条件可以减少氧化石墨烯表面的含氧官能团，主要归因于纳米材料的醌基团被氯氧化，以及被Cl•和/或ClO•自由基进一步氧化，使其发生还原并使其碳层发生破损。此外，随着氯化的程度增加，光氯化的程度减少，会导致光氯化纳米材料的胶体稳定性降低。纳米材料的抗菌作用随着氯化和光氯化作用的增加而增加。通过采集真实水样，研究了在真实水处理环境中碳纳米材料理化性质的变化规律，并检测了水中各种水质指标及水化学条件参数对其的影响。该研究探究了碳纳米材料在水处理过程中的物理化学变化机制，为进一步揭示人工纳米材料的环境行为和效应提供理论依据。